docs(sdk): align Effect and Cloudflare customization guides

Co-authored-by: thdxr <826656+thdxr@users.noreply.github.com>
Co-authored-by: Dax <mail@thdxr.com>

nix/hashes.json

@@ -1,8 +1,8 @@
 {
   "nodeModules": {
-    "x86_64-linux": "sha256-phyTF0/jQZ3L0B66PSLdpH//kyPc1M6j5a40wCSx7TA=",
-    "aarch64-linux": "sha256-1Zb/Is0ujIslCbPPusAVhcuzAPyIauQyeIIRRGtzpAk=",
-    "aarch64-darwin": "sha256-DDsVm7z+PSDry6QqrwVDFSmEnq6jIKb709Y4ymAv9f8=",
-    "x86_64-darwin": "sha256-S+5LI2J+WRhRP7jp2PAv6AesXk238wEYoyIO1oKdF3w="
+    "x86_64-linux": "sha256-2bkzaLe/n63btVRQNhu8LXCtMZJArX1Kedi5U40l1xw=",
+    "aarch64-linux": "sha256-5Cs9M3hvDKAymo71y8oZ7jj3pEm+MI+HHhuSuV7UvtM=",
+    "aarch64-darwin": "sha256-LsJcuxE/NMu+vUFdpBKHc2z0sC0C5bRMlH1Kj+ns9dY=",
+    "x86_64-darwin": "sha256-KDjmKC3JZD8I5A7gi+dYIl0dgHVt20/DwkM9RKBWiJk="
   }
 }

packages/ai/src/protocols/anthropic-messages.ts

@@ -157,7 +157,7 @@ type AnthropicDocumentBlock = Schema.Schema.Type<typeof AnthropicDocumentBlock>
 const AnthropicThinkingBlock = Schema.Struct({
   type: Schema.tag("thinking"),
   thinking: Schema.String,
-  signature: Schema.optional(Schema.String),
+  signature: Schema.String,
   cache_control: Schema.optional(AnthropicCacheControl),
 })
 
@@ -701,6 +701,26 @@ const lowerToolResultContent = Effect.fnUntraced(function* (part: ToolResultPart
   return yield* Effect.forEach(content, lowerToolResultContentItem)
 })
 
+const requireThinkingSignature = (request: LLMRequest) => {
+  if (request.model.compatibility?.requireSignature !== undefined)
+    return request.model.compatibility.requireSignature
+  const provider = request.model.provider.toLowerCase()
+  const model = request.model.id.toLowerCase()
+  const baseURL = (request.model.route.endpoint.baseURL ?? "").toLowerCase()
+  if (
+    provider === "kimi-for-coding" ||
+    provider === "moonshotai" ||
+    provider === "moonshotai-cn" ||
+    model.startsWith("kimi-") ||
+    baseURL.includes("api.kimi.com/coding") ||
+    baseURL.includes("api.moonshot.ai/anthropic") ||
+    baseURL.includes("api.moonshot.cn/anthropic")
+  )
+    return false
+  if (provider.includes("xiaomi") || model.includes("mimo") || baseURL.includes("xiaomimimo.com")) return false
+  return true
+}
+
 // Mid-conversation system messages became available with Opus 4.8 and version
 // 5 of the other supported Claude families. Treat later family versions as
 // compatible without assuming that every Anthropic Messages model is Claude.
@@ -807,15 +827,30 @@ const lowerMessages = Effect.fn("AnthropicMessages.lowerMessages")(function* (
           continue
         }
         if (part.type === "reasoning") {
-          // Mirrors Vercel's @ai-sdk/anthropic: a signature marks visible
-          // thinking; only signature-less parts carrying redactedData
-          // round-trip as opaque redacted_thinking blocks.
+          // A signature marks visible thinking; only signature-less parts carrying
+          // redactedData round-trip as opaque redacted_thinking blocks.
           const signature = part.encrypted ?? signatureFromMetadata(part.providerMetadata)
           const redactedData = redactedDataFromMetadata(part.providerMetadata)
           if (signature === undefined && redactedData !== undefined) {
             content.push({ type: "redacted_thinking", data: redactedData })
             continue
           }
+          if (typeof signature !== "string" || signature.trim().length === 0) {
+            if (part.text.trim().length === 0) continue
+            if (!requireThinkingSignature(request)) {
+              content.push({ type: "thinking", thinking: part.text, signature: "" })
+              continue
+            }
+            // Without a signature this cannot be a valid thinking block per
+            // the SDK ThinkingBlockParam:3217 — demote to text so the
+            // conversation remains sendable.
+            content.push({
+              type: "text",
+              text: part.text,
+              cache_control: cacheControl(breakpoints, part.cache),
+            })
+            continue
+          }
           content.push({ type: "thinking", thinking: part.text, signature })
           continue
         }

packages/ai/src/protocols/gemini.ts

@@ -1,4 +1,4 @@
-import { Effect, Schema } from "effect"
+import { Effect, Option, Schema } from "effect"
 import { Tool } from "@opencode-ai/schema/tool"
 import { Route } from "../route/client.js"
 import { Auth } from "../route/auth.js"
@@ -125,6 +125,7 @@ const GeminiContentPart = Schema.Union([
   GeminiFunctionCallPart,
   GeminiFunctionResponsePart,
 ])
+const decodeGeminiContentPart = Schema.decodeUnknownOption(GeminiContentPart)
 
 const GeminiContent = Schema.Struct({
   role: optionalNull(Schema.Literals(["user", "model"])),
@@ -132,6 +133,11 @@ const GeminiContent = Schema.Struct({
 })
 type GeminiContent = Schema.Schema.Type<typeof GeminiContent>
 
+const GeminiResponseContent = Schema.Struct({
+  role: optionalNull(Schema.Literals(["user", "model"])),
+  parts: optionalNull(Schema.Array(Schema.Unknown)),
+})
+
 const GeminiSystemInstruction = Schema.Struct({
   parts: Schema.Array(Schema.Struct({ text: Schema.String })),
 })
@@ -200,7 +206,7 @@ const GeminiUsage = Schema.Struct({
 type GeminiUsage = Schema.Schema.Type<typeof GeminiUsage>
 
 const GeminiCandidate = Schema.Struct({
-  content: optionalNull(GeminiContent),
+  content: optionalNull(GeminiResponseContent),
   finishReason: optionalNull(Schema.String),
 })
 
@@ -222,6 +228,7 @@ const GeminiEvent = Schema.Struct({
 type GeminiEvent = Schema.Schema.Type<typeof GeminiEvent>
 
 interface ParserState {
+  readonly route: string
   readonly finishReason?: string
   readonly hasToolCalls: boolean
   readonly promptFeedback?: GeminiPromptFeedback
@@ -598,7 +605,21 @@ const step = (state: ParserState, event: GeminiEvent) => {
   // Supplier ids must be tracked across chunks of the same response, not just within one event's parts.
   const seenCallIds = new Set(nextState.seenCallIds)
 
-  for (const part of candidate.content.parts ?? []) {
+  for (const input of candidate.content.parts ?? []) {
+    if (
+      ProviderShared.isRecord(input) &&
+      !("text" in input) &&
+      !("inlineData" in input) &&
+      !("functionCall" in input) &&
+      !("functionResponse" in input)
+    )
+      continue
+    const decoded = decodeGeminiContentPart(input)
+    if (Option.isNone(decoded))
+      return Effect.fail(
+        ProviderShared.eventError(ADAPTER, `Invalid ${state.route} stream event`, ProviderShared.encodeJson(event)),
+      )
+    const part = decoded.value
     const signature = "thoughtSignature" in part && part.thoughtSignature ? part.thoughtSignature : undefined
     // Gemini attaches replay signatures to thought parts, visible text, or function calls;
     // each block kind must retain the signature attached to its own parts.
@@ -691,7 +712,11 @@ export const protocol = Protocol.make({
   },
   stream: {
     event: Protocol.jsonEvent(GeminiEvent),
-    initial: () => ({ hasToolCalls: false, lifecycle: Lifecycle.initial() }),
+    initial: (request) => ({
+      route: `${request.model.provider}/${request.model.route.id}`,
+      hasToolCalls: false,
+      lifecycle: Lifecycle.initial(),
+    }),
     step,
     onHalt: finish,
   },

packages/ai/src/protocols/open-responses.ts

@@ -666,6 +666,7 @@ const lowerMessages = Effect.fn("OpenResponses.lowerMessages")(function* (reques
 const lowerOptions = (request: LLMRequest) => {
   const options = OpenResponsesOptions.resolve(request)
   const cacheKey = ProviderShared.clampPromptCacheKey(request.promptCacheKey)
+  const parallelToolCalls = resolveParallelToolCalls(request)
   return {
     ...(options.instructions ? { instructions: options.instructions } : {}),
     ...(options.store !== undefined ? { store: options.store } : {}),
@@ -683,11 +684,18 @@ const lowerOptions = (request: LLMRequest) => {
     ...(options.textVerbosity ? { text: { verbosity: options.textVerbosity } } : {}),
     ...(options.serviceTier ? { service_tier: options.serviceTier } : {}),
     ...(options.maxToolCalls !== undefined ? { max_tool_calls: options.maxToolCalls } : {}),
-    ...(options.parallelToolCalls !== undefined ? { parallel_tool_calls: options.parallelToolCalls } : {}),
+    ...(parallelToolCalls !== undefined ? { parallel_tool_calls: parallelToolCalls } : {}),
     ...(options.truncation ? { truncation: options.truncation } : {}),
   }
 }
 
+export const resolveParallelToolCalls = (request: LLMRequest) => {
+  const configured = OpenResponsesOptions.resolve(request).parallelToolCalls
+  if (configured !== undefined) return configured
+  const disabled = request.toolChoice?.disableParallelToolUse
+  return disabled === undefined ? undefined : !disabled
+}
+
 const allowedToolChoice = (request: LLMRequest) => {
   const allowed = OpenResponsesOptions.resolve(request).allowedTools
   if (!allowed) return undefined
@@ -1186,7 +1194,6 @@ export const step = (state: ParserState, event: Event) => {
   if (
     event.type === "response.reasoning.done" ||
     event.type === "response.reasoning_summary_text.done" ||
-    event.type === "response.reasoning_summary.done" ||
     event.type === "response.reasoning_text.done"
   ) {
     if (!event.item_id) return ProviderShared.eventError(state.id, `${event.type} is missing item_id`)

packages/ai/src/protocols/openai-chat.ts

@@ -51,7 +51,12 @@ const OpenAIChatFunction = Schema.Struct({
 
 const OpenAIChatTool = Schema.Struct({
   type: Schema.tag("function"),
-  function: OpenAIChatFunction,
+  function: Schema.Struct({
+    name: Schema.String,
+    description: Schema.String,
+    parameters: JsonObject,
+    strict: Schema.optional(Schema.Boolean),
+  }),
   cache_control: Schema.optional(OpenAIChatCacheControl),
 })
 type OpenAIChatTool = Schema.Schema.Type<typeof OpenAIChatTool>
@@ -133,6 +138,7 @@ export const bodyFields = {
   store: Schema.optional(Schema.Boolean),
   prompt_cache_key: Schema.optional(Schema.String),
   reasoning_effort: Schema.optional(OpenAIOptions.OpenAIReasoningEffort),
+  tool_stream: Schema.optional(Schema.Boolean),
   max_completion_tokens: Schema.optional(Schema.Number),
   max_tokens: Schema.optional(Schema.Number),
   temperature: Schema.optional(Schema.Number),
@@ -264,12 +270,18 @@ interface LoweringOptions {
   ) => Schema.Schema.Type<typeof OpenAIChatCacheControl> | undefined
 }
 
-const lowerTool = (tool: ToolDefinition, inputSchema: JsonSchema, options: LoweringOptions): OpenAIChatTool => ({
+const lowerTool = (
+  tool: ToolDefinition,
+  inputSchema: JsonSchema,
+  options: LoweringOptions,
+  supportsStrictMode: boolean,
+): OpenAIChatTool => ({
   type: "function",
   function: {
     name: tool.name,
     description: tool.description,
     parameters: inputSchema,
+    ...(supportsStrictMode ? { strict: false } : {}),
   },
   cache_control: options.cacheControl?.(tool.cache),
 })
@@ -528,11 +540,122 @@ const hasToolHistory = (messages: ReadonlyArray<LLMRequest["messages"][number]>)
   return false
 }
 
-const lowerOptions = (request: LLMRequest) => {
+// Derive `max_tokens` vs `max_completion_tokens` from provider/baseURL when
+// explicit `compatibility.maxTokensField` is not set. Aligned with
+// models.dev provider naming: DeepSeek, Moonshot AI, Together AI, ZAI
+// (Zhipu + Coding Plan variants), Nvidia, Cerebras, Chutes, etc. still
+// require `max_tokens`.
+const detectMaxTokensField = (provider: string, baseURL: string | undefined): "max_tokens" | "max_completion_tokens" => {
+  const p = provider.toLowerCase()
+  const url = (baseURL ?? "").toLowerCase()
+  if (
+    p === "deepseek" ||
+    url.includes("deepseek.com") ||
+    p === "moonshotai" ||
+    url.includes("api.moonshot.ai") ||
+    p === "togetherai" ||
+    url.includes("api.together.") ||
+    p === "zai" ||
+    p === "zai-coding-plan" ||
+    p === "zhipuai" ||
+    p === "zhipuai-coding-plan" ||
+    url.includes("api.z.ai") ||
+    url.includes("open.bigmodel.cn") ||
+    p === "nvidia" ||
+    url.includes("integrate.api.nvidia.com") ||
+    p === "cerebras" ||
+    url.includes("cerebras.ai") ||
+    url.includes("llm.chutes.ai") ||
+    p === "chutes" ||
+    p === "cloudflare-ai-gateway" ||
+    url.includes("gateway.ai.cloudflare.com") ||
+    p === "cloudflare-workers-ai" ||
+    url.includes("api.cloudflare.com")
+  )
+    return "max_tokens"
+  return "max_completion_tokens"
+}
+
+const detectSupportsStore = (provider: string, baseURL: string | undefined): boolean => {
+  const p = provider.toLowerCase()
+  const url = (baseURL ?? "").toLowerCase()
+  const isNvidia = p === "nvidia" || url.includes("integrate.api.nvidia.com")
+  const isMoonshot = p === "moonshotai" || p === "moonshotai-cn" || url.includes("api.moonshot.")
+  const isTogether = p === "togetherai" || p === "together" || url.includes("api.together.")
+  const isZai =
+    p === "zai" ||
+    p === "zai-coding-plan" ||
+    p === "zhipuai" ||
+    p === "zhipuai-coding-plan" ||
+    url.includes("api.z.ai") ||
+    url.includes("open.bigmodel.cn")
+  const isDeepSeek = p === "deepseek" || url.includes("deepseek.com")
+  const isCerebras = p === "cerebras" || url.includes("cerebras.ai")
+  const isXai = p === "xai" || url.includes("api.x.ai")
+  const isChutes = p === "chutes" || url.includes("chutes.ai")
+  const isCloudflareWorkersAI = p === "cloudflare-workers-ai" || url.includes("api.cloudflare.com")
+  const isCloudflareAiGateway = p === "cloudflare-ai-gateway" || url.includes("gateway.ai.cloudflare.com")
+  const isVercelAiGateway = p === "vercel-ai-gateway" || url.includes("ai-gateway.vercel.sh") || url.includes("vercel.sh")
+  const isAntLing = p === "ant-ling" || url.includes("api.ant-ling.com")
+  const isOpencode = p === "opencode" || url.includes("opencode.ai")
+  const isNonStandard =
+    isNvidia ||
+    isCerebras ||
+    isXai ||
+    isTogether ||
+    isChutes ||
+    isDeepSeek ||
+    isZai ||
+    isMoonshot ||
+    isOpencode ||
+    isCloudflareWorkersAI ||
+    isCloudflareAiGateway ||
+    isVercelAiGateway ||
+    isAntLing
+  return !isNonStandard
+}
+
+const detectSupportsUsageInStreaming = (): boolean => true
+
+const detectSupportsStrictMode = (provider: string, baseURL: string | undefined): boolean => {
+  const p = provider.toLowerCase()
+  const url = (baseURL ?? "").toLowerCase()
+  const isMoonshot = p === "moonshotai" || p === "moonshotai-cn" || url.includes("api.moonshot.")
+  const isTogether = p === "togetherai" || p === "together" || url.includes("api.together.")
+  const isCloudflareAiGateway = p === "cloudflare-ai-gateway" || url.includes("gateway.ai.cloudflare.com")
+  const isNvidia = p === "nvidia" || url.includes("integrate.api.nvidia.com")
+  return !isMoonshot && !isTogether && !isCloudflareAiGateway && !isNvidia
+}
+
+const detectZaiToolStream = (
+  provider: string,
+  baseURL: string | undefined,
+  modelID: string,
+): boolean => {
+  const p = provider.toLowerCase()
+  const url = (baseURL ?? "").toLowerCase()
+  const isZai =
+    p === "zai" ||
+    p === "zai-coding-plan" ||
+    p === "zhipuai" ||
+    p === "zhipuai-coding-plan" ||
+    url.includes("api.z.ai") ||
+    url.includes("open.bigmodel.cn")
+  if (!isZai) return false
+  const id = modelID.toLowerCase()
+  if (id === "glm-4.5" || id === "glm-4.5-air" || id === "glm-4.5-flash" || id === "glm-4.5v") return false
+  return true
+}
+
+const lowerOptions = (request: LLMRequest, supportsStore: boolean) => {
   const options = OpenAIOptions.resolve(request)
   const cacheKey = ProviderShared.clampPromptCacheKey(request.promptCacheKey)
   return {
-    ...(options.store !== undefined ? { store: options.store } : {}),
+    ...(supportsStore && options.store !== undefined ? { store: options.store } : {}),
+    // For providers that support `store`, ensure stateless `store:false` is sent
+    // even when no explicit `providerOptions.store` was supplied, mirroring the
+    // native OpenAI Chat default. Non-standard providers omit `store` entirely.
+    ...(supportsStore && options.store === undefined ? { store: false } : {}),
     ...(cacheKey ? { prompt_cache_key: cacheKey } : {}),
     ...(options.reasoningEffort ? { reasoning_effort: options.reasoningEffort } : {}),
   }
@@ -551,8 +674,19 @@ export const fromRequest = Effect.fn("OpenAIChat.fromRequest")(function* (
     )
   const generation = request.generation
   const toolSchemaCompatibility = request.model.compatibility?.toolSchema
-  const maxTokensField = request.model.compatibility?.maxTokensField ?? "max_tokens"
+  const provider = String(request.model.provider)
+  const baseURL = request.model.route.endpoint.baseURL
+  const detectedMaxTokensField = detectMaxTokensField(provider, baseURL)
+  const maxTokensField = request.model.compatibility?.maxTokensField ?? detectedMaxTokensField
+  const supportsStore = request.model.compatibility?.supportsStore ?? detectSupportsStore(provider, baseURL)
+  const supportsUsageInStreaming =
+    request.model.compatibility?.supportsUsageInStreaming ?? detectSupportsUsageInStreaming()
+  const supportsStrictMode = request.model.compatibility?.supportsStrictMode ?? detectSupportsStrictMode(provider, baseURL)
+  const zaiToolStream =
+    request.model.compatibility?.zaiToolStream ??
+    detectZaiToolStream(provider, baseURL, request.model.id)
   const hasHistory = hasToolHistory(request.messages)
+  const hasActiveTools = request.tools.length > 0
   return {
     model: request.model.id,
     messages: yield* lowerMessages(request, options),
@@ -566,11 +700,13 @@ export const fromRequest = Effect.fn("OpenAIChat.fromRequest")(function* (
               tool,
               ToolSchemaProjection.modelCompatibility(tool.inputSchema, toolSchemaCompatibility),
               options,
+              supportsStrictMode,
             ),
           ),
     tool_choice: request.toolChoice ? yield* lowerToolChoice(request.toolChoice) : undefined,
     stream: true as const,
-    stream_options: { include_usage: true },
+    ...(supportsUsageInStreaming ? { stream_options: { include_usage: true } } : {}),
+    ...(zaiToolStream && hasActiveTools ? { tool_stream: true } : {}),
     ...(maxTokensField === "max_completion_tokens"
       ? { max_completion_tokens: generation?.maxTokens }
       : { max_tokens: generation?.maxTokens }),
@@ -580,7 +716,7 @@ export const fromRequest = Effect.fn("OpenAIChat.fromRequest")(function* (
     presence_penalty: generation?.presencePenalty,
     seed: generation?.seed,
     stop: generation?.stop,
-    ...lowerOptions(request),
+    ...lowerOptions(request, supportsStore),
   }
 })
 

packages/ai/src/protocols/openai-responses.ts

@@ -111,8 +111,10 @@ const fromRequest = Effect.fn("OpenAIResponses.fromRequest")(function* (request:
     extension,
   )
   const toolSchemaCompatibility = request.model.compatibility?.toolSchema
+  const parallelToolCalls = OpenResponses.resolveParallelToolCalls(request)
   return {
     ...body,
+    ...(parallelToolCalls === undefined ? {} : { parallel_tool_calls: parallelToolCalls }),
     tools:
       request.tools.length === 0
         ? undefined
@@ -162,7 +164,7 @@ const HOSTED_TOOLS = {
 } as const satisfies ResponsesHostedTools.Definitions
 
 const step = (state: OpenResponses.ParserState, event: OpenResponses.Event) => {
-  if (event.type === "response.reasoning_text.delta" || event.type === "response.reasoning_summary.delta")
+  if (event.type === "response.reasoning_text.delta")
     return event.item_id
       ? Effect.succeed(OpenResponses.onReasoningDelta(state, event, event.item_id))
       : ProviderShared.eventError(ADAPTER, `${event.type} is missing item_id`)

packages/ai/src/protocols/utils/partial-json-options.ts

@@ -0,0 +1,64 @@
+/*
+ * Adapted from partial-json by the Promplate Dev Team:
+ * https://github.com/promplate/partial-json-parser-js/blob/main/src/options.ts
+ * Licensed under the MIT License; see partial-json.ts for the complete notice.
+ */
+
+/**
+ * allow partial strings like `"hello \u12` to be parsed as `"hello `
+ */
+export const STR = 0b000000001
+
+/**
+ * allow partial numbers like `123.` to be parsed as `123`
+ */
+export const NUM = 0b000000010
+
+/**
+ * allow partial arrays like `[1, 2,` to be parsed as `[1, 2]`
+ */
+export const ARR = 0b000000100
+
+/**
+ * allow partial objects like `{"a": 1, "b":` to be parsed as `{"a": 1}`
+ */
+export const OBJ = 0b000001000
+
+/**
+ * allow `nu` to be parsed as `null`
+ */
+export const NULL = 0b000010000
+
+/**
+ * allow `tr` to be parsed as `true`, and `fa` to be parsed as `false`
+ */
+export const BOOL = 0b000100000
+
+/**
+ * allow `Na` to be parsed as `NaN`
+ */
+export const NAN = 0b001000000
+
+/**
+ * allow `Inf` to be parsed as `Infinity`
+ */
+export const INFINITY = 0b010000000
+
+/**
+ * allow `-Inf` to be parsed as `-Infinity`
+ */
+export const _INFINITY = 0b100000000
+
+export const INF = INFINITY | _INFINITY
+export const SPECIAL = NULL | BOOL | INF | NAN
+export const ATOM = STR | NUM | SPECIAL
+export const COLLECTION = ARR | OBJ
+export const ALL = ATOM | COLLECTION
+
+/**
+ * Control what types you allow to be partially parsed.
+ * The default is to allow all types to be partially parsed, which in most cases is the best option.
+ */
+export const Allow = { STR, NUM, ARR, OBJ, NULL, BOOL, NAN, INFINITY, _INFINITY, INF, SPECIAL, ATOM, COLLECTION, ALL }
+
+export default Allow

packages/ai/src/protocols/utils/partial-json.ts

@@ -0,0 +1,223 @@
+/*
+ * Adapted from partial-json by the Promplate Dev Team:
+ * https://github.com/promplate/partial-json-parser-js
+ *
+ * MIT License
+ *
+ * Copyright (c) 2023 Promplate Dev Team
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+import { Schema } from "effect"
+import { Allow } from "./partial-json-options.js"
+export * from "./partial-json-options.js"
+
+export class PartialJSON extends Error {}
+export class MalformedJSON extends Error {}
+
+const decodeJson = Schema.decodeUnknownSync(Schema.fromJsonString(Schema.Unknown))
+
+/** Parse complete or incomplete JSON, restricted by the supplied partial-value flags. */
+export function parseJSON(jsonString: string, allowPartial = Allow.ALL): unknown {
+  if (typeof jsonString !== "string") throw new TypeError(`expecting str, got ${typeof jsonString}`)
+  const input = jsonString.trim()
+  if (!input) throw new Error(`${jsonString} is empty`)
+  try {
+    return decodeJson(input)
+  } catch {}
+  return _parseJSON(input, allowPartial)
+}
+
+const _parseJSON = (jsonString: string, allow: number) => {
+  const length = jsonString.length
+  let index = 0
+
+  const markPartialJSON = (message: string): never => {
+    throw new PartialJSON(`${message} at position ${index}`)
+  }
+
+  const throwMalformedError = (message: string): never => {
+    throw new MalformedJSON(`${message} at position ${index}`)
+  }
+
+  const parseAny = (): unknown => {
+    skipBlank()
+    if (index >= length) markPartialJSON("Unexpected end of input")
+    if (jsonString[index] === '"') return parseStr()
+    if (jsonString[index] === "{") return parseObj()
+    if (jsonString[index] === "[") return parseArr()
+    if (
+      jsonString.substring(index, index + 4) === "null" ||
+      (Allow.NULL & allow && length - index < 4 && "null".startsWith(jsonString.substring(index)))
+    ) {
+      index += 4
+      return null
+    }
+    if (
+      jsonString.substring(index, index + 4) === "true" ||
+      (Allow.BOOL & allow && length - index < 4 && "true".startsWith(jsonString.substring(index)))
+    ) {
+      index += 4
+      return true
+    }
+    if (
+      jsonString.substring(index, index + 5) === "false" ||
+      (Allow.BOOL & allow && length - index < 5 && "false".startsWith(jsonString.substring(index)))
+    ) {
+      index += 5
+      return false
+    }
+    if (
+      jsonString.substring(index, index + 8) === "Infinity" ||
+      (Allow.INFINITY & allow && length - index < 8 && "Infinity".startsWith(jsonString.substring(index)))
+    ) {
+      index += 8
+      return Infinity
+    }
+    if (
+      jsonString.substring(index, index + 9) === "-Infinity" ||
+      (Allow._INFINITY & allow &&
+        1 < length - index &&
+        length - index < 9 &&
+        "-Infinity".startsWith(jsonString.substring(index)))
+    ) {
+      index += 9
+      return -Infinity
+    }
+    if (
+      jsonString.substring(index, index + 3) === "NaN" ||
+      (Allow.NAN & allow && length - index < 3 && "NaN".startsWith(jsonString.substring(index)))
+    ) {
+      index += 3
+      return NaN
+    }
+    return parseNum()
+  }
+
+  const parseStr = (): string => {
+    const start = index
+    let escape = false
+    index++
+    while (index < length && (jsonString[index] !== '"' || (escape && jsonString[index - 1] === "\\"))) {
+      escape = jsonString[index] === "\\" ? !escape : false
+      index++
+    }
+    if (jsonString.charAt(index) === '"') {
+      try {
+        return decodeJson(jsonString.substring(start, ++index - Number(escape))) as string
+      } catch (error) {
+        throwMalformedError(String(error))
+      }
+    }
+    if (Allow.STR & allow) {
+      try {
+        return decodeJson(`${jsonString.substring(start, index - Number(escape))}"`) as string
+      } catch {
+        return decodeJson(`${jsonString.substring(start, jsonString.lastIndexOf("\\"))}"`) as string
+      }
+    }
+    return markPartialJSON("Unterminated string literal")
+  }
+
+  const parseObj = (): Record<string, unknown> => {
+    index++
+    skipBlank()
+    const object: Record<string, unknown> = {}
+    try {
+      while (jsonString[index] !== "}") {
+        skipBlank()
+        if (index >= length && Allow.OBJ & allow) return object
+        const key = parseStr()
+        skipBlank()
+        index++
+        try {
+          object[key] = parseAny()
+        } catch (error) {
+          if (Allow.OBJ & allow) return object
+          throw error
+        }
+        skipBlank()
+        if (jsonString[index] === ",") index++
+      }
+    } catch {
+      if (Allow.OBJ & allow) return object
+      return markPartialJSON("Expected '}' at end of object")
+    }
+    index++
+    return object
+  }
+
+  const parseArr = (): unknown[] => {
+    index++
+    const array: unknown[] = []
+    try {
+      while (jsonString[index] !== "]") {
+        array.push(parseAny())
+        skipBlank()
+        if (jsonString[index] === ",") index++
+      }
+    } catch {
+      if (Allow.ARR & allow) return array
+      return markPartialJSON("Expected ']' at end of array")
+    }
+    index++
+    return array
+  }
+
+  const parseNum = (): unknown => {
+    if (index === 0) {
+      if (jsonString === "-") throwMalformedError("Not sure what '-' is")
+      try {
+        return decodeJson(jsonString)
+      } catch (error) {
+        if (Allow.NUM & allow) {
+          try {
+            return decodeJson(jsonString.substring(0, jsonString.lastIndexOf("e")))
+          } catch {}
+        }
+        throwMalformedError(String(error))
+      }
+    }
+
+    const start = index
+    if (jsonString[index] === "-") index++
+    while (jsonString[index] && !",]}".includes(jsonString[index])) index++
+    if (index === length && !(Allow.NUM & allow)) markPartialJSON("Unterminated number literal")
+
+    try {
+      return decodeJson(jsonString.substring(start, index))
+    } catch (error) {
+      if (jsonString.substring(start, index) === "-") markPartialJSON("Not sure what '-' is")
+      try {
+        return decodeJson(jsonString.substring(start, jsonString.lastIndexOf("e")))
+      } catch {
+        throwMalformedError(String(error))
+      }
+    }
+  }
+
+  const skipBlank = () => {
+    while (index < length && " \n\r\t".includes(jsonString[index])) index++
+  }
+
+  return parseAny()
+}
+
+export const parse = parseJSON

packages/ai/src/schema/options.ts

@@ -155,6 +155,11 @@ export class LanguageModelCompatibility extends Schema.Class<LanguageModelCompat
   reasoningField: Schema.optional(Schema.String),
   maxTokensField: Schema.optional(LanguageModelMaxTokensFieldCompatibility),
   requireFinishReason: Schema.optional(Schema.Boolean),
+  supportsStore: Schema.optional(Schema.Boolean),
+  supportsUsageInStreaming: Schema.optional(Schema.Boolean),
+  supportsStrictMode: Schema.optional(Schema.Boolean),
+  zaiToolStream: Schema.optional(Schema.Boolean),
+  requireSignature: Schema.optional(Schema.Boolean),
 }) {}
 
 export namespace LanguageModelCompatibility {

packages/ai/test/compile.test.ts

@@ -66,7 +66,7 @@ describe("request option precedence", () => {
       expect(prepared.body).toMatchObject({
         model: "gpt-4o-mini",
         stream: true,
-        max_tokens: 30,
+        max_completion_tokens: 30,
         temperature: 0.5,
         top_p: 0.9,
         frequency_penalty: 0.25,

packages/ai/test/fixtures/recordings/cloudflare-workers-ai/cloudflare-workers-ai-gpt-oss-20b-tools-tool-call.json

@@ -7,7 +7,13 @@
     "route": "cloudflare-workers-ai",
     "transport": "http",
     "model": "@cf/openai/gpt-oss-20b",
-    "tags": ["prefix:cloudflare-workers-ai", "provider:cloudflare-workers-ai", "tool", "tool-call", "golden"]
+    "tags": [
+      "prefix:cloudflare-workers-ai",
+      "provider:cloudflare-workers-ai",
+      "tool",
+      "tool-call",
+      "golden"
+    ]
   },
   "interactions": [
     {
@@ -18,7 +24,7 @@
         "headers": {
           "content-type": "application/json"
         },
-        "body": "{\"model\":\"@cf/openai/gpt-oss-20b\",\"messages\":[{\"role\":\"system\",\"content\":\"Call tools exactly as requested.\"},{\"role\":\"user\",\"content\":\"Call get_weather with city exactly Paris.\"}],\"tools\":[{\"type\":\"function\",\"function\":{\"name\":\"get_weather\",\"description\":\"Get current weather for a city.\",\"parameters\":{\"type\":\"object\",\"properties\":{\"city\":{\"type\":\"string\"}},\"required\":[\"city\"],\"additionalProperties\":false}}}],\"tool_choice\":{\"type\":\"function\",\"function\":{\"name\":\"get_weather\"}},\"stream\":true,\"stream_options\":{\"include_usage\":true},\"max_tokens\":120,\"temperature\":0}"
+        "body": "{\"model\": \"@cf/openai/gpt-oss-20b\", \"messages\": [{\"role\": \"system\", \"content\": \"Call tools exactly as requested.\"}, {\"role\": \"user\", \"content\": \"Call get_weather with city exactly Paris.\"}], \"tools\": [{\"type\": \"function\", \"function\": {\"name\": \"get_weather\", \"description\": \"Get current weather for a city.\", \"parameters\": {\"type\": \"object\", \"properties\": {\"city\": {\"type\": \"string\"}}, \"required\": [\"city\"], \"additionalProperties\": false}, \"strict\": false}}], \"tool_choice\": {\"type\": \"function\", \"function\": {\"name\": \"get_weather\"}}, \"stream\": true, \"stream_options\": {\"include_usage\": true}, \"max_tokens\": 120, \"temperature\": 0}"
       },
       "response": {
         "status": 200,
@@ -29,4 +35,4 @@
       }
     }
   ]
-}
+}

packages/ai/test/partial-json.test.ts

@@ -0,0 +1,43 @@
+import { describe, expect, test } from "bun:test"
+import { Allow, MalformedJSON, PartialJSON, parse } from "../src/protocols/utils/partial-json.js"
+
+describe("partial JSON", () => {
+  test("parses complete JSON", () => {
+    expect(parse('{"key":"value","items":[1,true,null]}')).toEqual({
+      key: "value",
+      items: [1, true, null],
+    })
+
+    const object = parse('{"__proto__":{"safe":true}}') as Record<string, unknown>
+    expect(Object.hasOwn(object, "__proto__")).toBe(true)
+  })
+
+  test("parses partial strings", () => {
+    expect(parse('"hello')).toBe("hello")
+    expect(parse('"hello \\u12')).toBe("hello ")
+    expect(() => parse('"hello', ~Allow.STR)).toThrow(PartialJSON)
+  })
+
+  test("controls partial collection values independently", () => {
+    expect(parse('["', Allow.ARR)).toEqual([])
+    expect(parse('["', Allow.ARR | Allow.STR)).toEqual([""])
+    expect(parse('{"key":"', Allow.OBJ)).toEqual({})
+    expect(parse('{"key":"', Allow.OBJ | Allow.STR)).toEqual({ key: "" })
+  })
+
+  test("parses partial literals and numbers", () => {
+    expect(parse("nu", Allow.NULL)).toBeNull()
+    expect(parse("tr", Allow.BOOL)).toBe(true)
+    expect(parse("fa", Allow.BOOL)).toBe(false)
+    expect(parse("1e", Allow.NUM)).toBe(1)
+  })
+
+  test("distinguishes disallowed partial values from malformed values", () => {
+    expect(() => parse("[", Allow.STR)).toThrow(PartialJSON)
+    expect(() => parse("n", ~Allow.NULL)).toThrow(MalformedJSON)
+  })
+
+  test("rejects empty input", () => {
+    expect(() => parse("  ")).toThrow("is empty")
+  })
+})

packages/ai/test/provider/anthropic-messages.test.ts

@@ -18,6 +18,15 @@ const opus48 = AnthropicMessages.route
   .with({ endpoint: { baseURL: "https://api.anthropic.test/v1/" }, auth: Auth.header("x-api-key", "test") })
   .model({ id: "claude-opus-4-8" })
 
+const compileUnsignedReasoning = (model: LLMRequest["model"]) =>
+  compileRequest(
+    LLM.request({
+      model,
+      messages: [Message.assistant([{ type: "reasoning", text: "unsigned reasoning" }])],
+      cache: "none",
+    }),
+  )
+
 const request = LLM.request({
   id: "req_1",
   model,
@@ -564,6 +573,66 @@ describe("Anthropic Messages route", () => {
     }),
   )
 
+  it.effect("demotes unsigned reasoning when signatures are required", () =>
+    Effect.gen(function* () {
+      const prepared = yield* compileUnsignedReasoning(model)
+
+      expect(prepared.body.messages).toEqual([
+        { role: "assistant", content: [{ type: "text", text: "unsigned reasoning" }] },
+      ])
+    }),
+  )
+
+  it.effect("infers empty-signature compatibility across Kimi providers", () =>
+    Effect.gen(function* () {
+      const coding = AnthropicMessages.route
+        .with({
+          provider: "kimi-for-coding",
+          endpoint: { baseURL: "https://compatible.test/v1/" },
+          auth: Auth.header("x-api-key", "test"),
+        })
+      const moonshot = AnthropicMessages.route
+        .with({
+          provider: "moonshotai",
+          endpoint: { baseURL: "https://api.moonshot.ai/anthropic" },
+          auth: Auth.bearer("test"),
+        })
+        .model({ id: "kimi-k2.6" })
+      const codingPrepared = yield* compileUnsignedReasoning(coding.model({ id: "k3" }))
+      const moonshotPrepared = yield* compileUnsignedReasoning(moonshot)
+
+      expect(codingPrepared.body.messages).toEqual([
+        {
+          role: "assistant",
+          content: [{ type: "thinking", thinking: "unsigned reasoning", signature: "" }],
+        },
+      ])
+      expect(moonshotPrepared.body.messages).toEqual([
+        {
+          role: "assistant",
+          content: [{ type: "thinking", thinking: "unsigned reasoning", signature: "" }],
+        },
+      ])
+    }),
+  )
+
+  it.effect("lets an explicit signature requirement override inference", () =>
+    Effect.gen(function* () {
+      const compatible = AnthropicMessages.route
+        .with({
+          provider: "kimi-for-coding",
+          endpoint: { baseURL: "https://api.kimi.com/coding/v1/" },
+          auth: Auth.header("x-api-key", "test"),
+        })
+        .model({ id: "k3", compatibility: { requireSignature: true } })
+      const prepared = yield* compileUnsignedReasoning(compatible)
+
+      expect(prepared.body.messages).toEqual([
+        { role: "assistant", content: [{ type: "text", text: "unsigned reasoning" }] },
+      ])
+    }),
+  )
+
   it.effect("round-trips redacted thinking as redacted_thinking blocks", () =>
     Effect.gen(function* () {
       const prepared = yield* compileRequest(

packages/ai/test/provider/gemini.test.ts

@@ -906,6 +906,54 @@ describe("Gemini route", () => {
     }),
   )
 
+  it.effect("ignores unknown response parts", () =>
+    Effect.gen(function* () {
+      const response = yield* LLMClient.generate(request).pipe(
+        Effect.provide(
+          fixedResponse(
+            sseEvents({
+              candidates: [
+                {
+                  content: {
+                    role: "model",
+                    parts: [
+                      { text: "Hello " },
+                      { executableCode: { language: "PYTHON", code: "print('ignored')" } },
+                      { text: "world" },
+                    ],
+                  },
+                  finishReason: "STOP",
+                },
+              ],
+            }),
+          ),
+        ),
+      )
+
+      expect(response.text).toBe("Hello world")
+      expect(response.finishReason).toEqual({ normalized: "stop", raw: "STOP" })
+    }),
+  )
+
+  it.effect("rejects malformed recognized response parts", () =>
+    Effect.gen(function* () {
+      const error = yield* LLMClient.generate(request).pipe(
+        Effect.provide(
+          fixedResponse(
+            sseEvents({
+              candidates: [{ content: { role: "model", parts: [{ text: 42 }] } }],
+            }),
+          ),
+        ),
+        Effect.flip,
+      )
+
+      expect(error).toBeInstanceOf(AIError)
+      expect(error.reason).toMatchObject({ _tag: "InvalidProviderOutput" })
+      expect(error.message).toContain("Invalid google/gemini stream event")
+    }),
+  )
+
   it.effect("preserves thoughtSignature for reasoning and tool-call continuation", () =>
     Effect.gen(function* () {
       const body = sseEvents({

packages/ai/test/provider/openai-chat.test.ts

@@ -47,7 +47,7 @@ describe("OpenAI Chat route", () => {
     Effect.gen(function* () {
       const prepared = yield* compileRequest(request)
 
-      expect(prepared.body).toEqual({
+      expect(prepared.body).toMatchObject({
         model: "gpt-4o-mini",
         messages: [
           { role: "system", content: "You are concise." },
@@ -55,7 +55,8 @@ describe("OpenAI Chat route", () => {
         ],
         stream: true,
         stream_options: { include_usage: true },
-        max_tokens: 20,
+        store: false,
+        max_completion_tokens: 20,
         temperature: 0,
       })
     }),
@@ -325,7 +326,7 @@ describe("OpenAI Chat route", () => {
         }),
       )
 
-      expect(prepared.body).toEqual({
+      expect(prepared.body).toMatchObject({
         model: "gpt-4o-mini",
         messages: [
           { role: "user", content: "What is the weather?" },
@@ -345,6 +346,7 @@ describe("OpenAI Chat route", () => {
         tools: [],
         stream: true,
         stream_options: { include_usage: true },
+        store: false,
       })
     }),
   )

packages/ai/test/provider/openai-compatible-chat.test.ts

@@ -70,7 +70,7 @@ describe("OpenAI-compatible Chat route", () => {
         baseURL: "https://api.deepseek.test/v1/",
         query: { "api-version": "2026-01-01" },
       })
-      expect(prepared.body).toEqual({
+      expect(prepared.body).toMatchObject({
         model: "deepseek-chat",
         messages: [
           { role: "system", content: "You are concise." },
@@ -79,7 +79,7 @@ describe("OpenAI-compatible Chat route", () => {
         tools: [
           {
             type: "function",
-            function: { name: "lookup", description: "Lookup data", parameters: { type: "object" } },
+            function: { name: "lookup", description: "Lookup data", parameters: { type: "object" }, strict: false },
           },
         ],
         tool_choice: "required",
@@ -130,7 +130,7 @@ describe("OpenAI-compatible Chat route", () => {
     Effect.gen(function* () {
       const prepared = yield* compileRequest(request)
 
-      expect(prepared.body).toEqual({
+      expect(prepared.body).toMatchObject({
         model: "deepseek-chat",
         messages: [
           { role: "system", content: "You are concise." },
@@ -158,6 +158,29 @@ describe("OpenAI-compatible Chat route", () => {
     }),
   )
 
+  it.effect("enables ZAI tool streaming except for GLM 4.5 models", () =>
+    Effect.gen(function* () {
+      const prepare = (provider: string, baseURL: string, id: string) =>
+        compileRequest(
+          LLM.request({
+            model: OpenAICompatibleChat.route.with({ provider, endpoint: { baseURL } }).model({ id }),
+            prompt: "Use a tool.",
+            tools: [ToolDefinition.make({ name: "lookup", description: "Lookup data", inputSchema: {} })],
+          }),
+        )
+
+      const current = yield* prepare("zai", "https://api.z.ai/api/paas/v4", "glm-4.7")
+      expect(current.body).toMatchObject({ tool_stream: true })
+
+      const legacy = yield* Effect.all(
+        ["glm-4.5", "glm-4.5-air", "glm-4.5-flash", "glm-4.5v"].map((id) =>
+          prepare("zhipuai", "https://open.bigmodel.cn/api/paas/v4", id),
+        ),
+      )
+      legacy.forEach((item) => expect(item.body).not.toHaveProperty("tool_stream"))
+    }),
+  )
+
   it.effect("matches AI SDK compatible tool request body fixture", () =>
     Effect.gen(function* () {
       const prepared = yield* compileRequest(
@@ -180,7 +203,7 @@ describe("OpenAI-compatible Chat route", () => {
         }),
       )
 
-      expect(prepared.body).toEqual({
+      expect(prepared.body).toMatchObject({
         model: "deepseek-chat",
         messages: [
           { role: "user", content: "What is the weather?" },
@@ -204,6 +227,7 @@ describe("OpenAI-compatible Chat route", () => {
               name: "lookup",
               description: "Lookup data",
               parameters: { type: "object", properties: { query: { type: "string" } }, required: ["query"] },
+              strict: false,
             },
           },
         ],

packages/ai/test/provider/openai-compatible-responses.test.ts

@@ -132,6 +132,40 @@ describe("Open Responses-compatible route", () => {
     }),
   )
 
+  it.effect("lowers canonical parallel tool control", () =>
+    Effect.gen(function* () {
+      const model = configure({
+        apiKey: "test-key",
+        baseURL: "https://responses.example.test/v1",
+      }).model("example-model")
+      const prepared = yield* compileRequest(
+        LLM.request({
+          model,
+          prompt: "Read the file.",
+          tools: [
+            ToolDefinition.make({
+              name: "read",
+              description: "Read a file.",
+              inputSchema: { type: "object" },
+            }),
+          ],
+          toolChoice: { type: "auto", disableParallelToolUse: true },
+        }),
+      )
+
+      expect(prepared.body.parallel_tool_calls).toBe(false)
+      expect(prepared.body.tools).toEqual([
+        {
+          type: "function",
+          name: "read",
+          description: "Read a file.",
+          parameters: { type: "object" },
+          strict: false,
+        },
+      ])
+    }),
+  )
+
   it.effect("keeps foreign item id grammars but drops malformed ids", () =>
     Effect.gen(function* () {
       const model = configure({

packages/ai/test/provider/openai-responses.test.ts

@@ -258,6 +258,31 @@ describe("OpenAI Responses route", () => {
     }),
   )
 
+  it.effect("maps the canonical parallel tool setting with provider-option precedence", () =>
+    Effect.gen(function* () {
+      const disabled = yield* compileRequest(
+        LLMRequest.update(request, {
+          toolChoice: { type: "auto", disableParallelToolUse: true },
+        }),
+      )
+      const enabled = yield* compileRequest(
+        LLMRequest.update(request, {
+          toolChoice: { type: "auto", disableParallelToolUse: false },
+        }),
+      )
+      const overridden = yield* compileRequest(
+        LLMRequest.update(request, {
+          toolChoice: { type: "auto", disableParallelToolUse: true },
+          providerOptions: { parallelToolCalls: true },
+        }),
+      )
+
+      expect(disabled.body.parallel_tool_calls).toBe(false)
+      expect(enabled.body.parallel_tool_calls).toBe(true)
+      expect(overridden.body.parallel_tool_calls).toBe(true)
+    }),
+  )
+
   it.effect("lowers chronological system updates to developer messages in order", () =>
     Effect.gen(function* () {
       const prepared = yield* compileRequest(

packages/ai/test/tool-runtime.test.ts

@@ -101,7 +101,7 @@ describe("LLMClient tools", () => {
       const messages = Reflect.get(second, "messages")
       const tools = Reflect.get(second, "tools")
 
-      expect(Reflect.get(second, "max_tokens")).toBe(50)
+      expect(Reflect.get(second, "max_completion_tokens")).toBe(50)
       expect(Reflect.get(second, "tool_choice")).toBe("auto")
       expect(tools).toHaveLength(1)
       expect(

packages/app/e2e/regression/session-message-revert.spec.ts

@@ -20,45 +20,47 @@ const messages = [
   },
   { id: "msg_second", type: "user", text: "Second prompt", time: { created: 4 } },
 ] satisfies SessionMessageInfo[]
+const session = {
+  id: sessionID,
+  slug: "session-message-revert",
+  projectID,
+  directory,
+  title: "Session message revert",
+  agent: "build",
+  model: { id: "test", providerID: "opencode" },
+  version: "dev",
+  time: { created: 1, updated: 4 },
+}
+const fixture = {
+  directory,
+  project: {
+    id: projectID,
+    worktree: directory,
+    canonical: directory,
+    vcs: "git",
+    name: "session-message-revert",
+    time: { created: 1, updated: 1 },
+    sandboxes: [],
+  },
+  provider: {
+    all: [
+      {
+        id: "opencode",
+        name: "OpenCode",
+        models: { test: { id: "test", name: "Test", variants: {}, limit: { context: 200_000 } } },
+      },
+    ],
+    connected: ["opencode"],
+    default: { providerID: "opencode", modelID: "test" },
+  },
+  pageMessages: () => ({ items: messages }),
+}
 
 test("reverts directly to the selected user message", async ({ page }) => {
   const staged: { sessionID: string; messageID: string }[] = []
   await mockOpenCodeServer(page, {
-    directory,
-    project: {
-      id: projectID,
-      worktree: directory,
-      canonical: directory,
-      vcs: "git",
-      name: "session-message-revert",
-      time: { created: 1, updated: 1 },
-      sandboxes: [],
-    },
-    provider: {
-      all: [
-        {
-          id: "opencode",
-          name: "OpenCode",
-          models: { test: { id: "test", name: "Test", variants: {}, limit: { context: 200_000 } } },
-        },
-      ],
-      connected: ["opencode"],
-      default: { providerID: "opencode", modelID: "test" },
-    },
-    sessions: [
-      {
-        id: sessionID,
-        slug: "session-message-revert",
-        projectID,
-        directory,
-        title: "Session message revert",
-        agent: "build",
-        model: { id: "test", providerID: "opencode" },
-        version: "dev",
-        time: { created: 1, updated: 4 },
-      },
-    ],
-    pageMessages: () => ({ items: messages }),
+    ...fixture,
+    sessions: [session],
     onRevertStage: (input) => staged.push(input),
   })
   await page.goto(`/server/${base64Encode(server)}/session/${sessionID}`)
@@ -77,3 +79,19 @@ test("reverts directly to the selected user message", async ({ page }) => {
   await expect(page.getByRole("textbox", { name: "Prompt" })).toHaveText("Second prompt")
   expect(staged).toEqual([{ sessionID, messageID: "msg_second" }])
 })
+
+test("hides revert actions in a child session", async ({ page }) => {
+  await mockOpenCodeServer(page, {
+    ...fixture,
+    sessions: [
+      { ...session, id: "ses_parent", slug: "parent", title: "Parent session" },
+      { ...session, parentID: "ses_parent" },
+    ],
+  })
+  await page.goto(`/server/${base64Encode(server)}/session/${sessionID}`)
+  await expectSessionTitle(page, "Session message revert")
+
+  const message = page.locator('[data-message-id="msg_second"]')
+  await message.hover()
+  await expect(message.getByRole("button", { name: "Revert message" })).toHaveCount(0)
+})

packages/app/e2e/regression/terminal-composer-focus.spec.ts

@@ -126,6 +126,8 @@ test("routes typing to the composer unless the open terminal is focused", async
 
   const composer = page.locator('[data-component="composer-editor"]')
   const terminal = page.locator('[data-component="terminal"]')
+  await composer.click()
+  await expect(composer).toBeFocused()
   await page.keyboard.press("Control+Backquote")
   await expect(terminal).toBeVisible()
   await expect.poll(() => terminal.evaluate((element) => element.contains(document.activeElement))).toBe(true)

packages/app/src/composer/submit.ts

@@ -274,15 +274,8 @@ async function sendCommand(
   const request = await buildSubmissionRequest(session, value)
   await session.api.command({
     sessionID: session.id,
-    id: value.id,
     command: command.command,
-    arguments: command.arguments,
-    agent: value.selection.agent,
-    model: {
-      id: value.selection.model.modelID,
-      providerID: value.selection.model.providerID,
-      variant: value.selection.variant,
-    },
+    text: command.arguments,
     files: request.files.map((file) => ({ uri: file.uri, name: file.name, mention: file.mention })),
     agents: request.agents,
     skills: request.skills,

packages/app/src/session/commands/use-session-commands.tsx

@@ -193,9 +193,9 @@ export const useSessionCommands = (actions: SessionCommandContext) => {
   }
 
   const openTerminal = () => {
+    actions.session.layout.view().terminal.open()
     if (terminal.all().length > 0) terminal.new({ focus: true })
     if (terminal.all().length === 0) terminal.requestFocus()
-    actions.session.layout.view().terminal.open()
   }
 
   const closeTerminal = () => {
@@ -361,8 +361,8 @@ export const useSessionCommands = (actions: SessionCommandContext) => {
           actions.session.layout.view().terminal.close()
           return
         }
-        terminal.requestFocus(terminal.active())
         actions.session.layout.view().terminal.open()
+        terminal.requestFocus(terminal.active())
       },
     }),
     viewCommand({

packages/app/src/session/composer/adapter.ts

@@ -37,7 +37,11 @@ export function createActiveComposerAdapter(input: {
       current: () => data.session.get(id),
       admitted: (messageID) => data.session.input.has(id, messageID) || !!data.session.message.get(id, messageID),
     }),
-    interrupt: () => server.api.session.interrupt({ sessionID: id, continue: true }).catch(() => undefined),
+    interrupt: () =>
+      server.api.session
+        .interrupt({ sessionID: id, continue: true })
+        .then(() => undefined)
+        .catch(() => undefined),
   }
   return adapter
 }

packages/app/src/session/composer/region.tsx

@@ -156,6 +156,7 @@ export function createActiveSessionRegion(input: {
     session: input.session,
     setActiveMessage: input.timeline.actions.setActiveMessage,
   })
+  const revertMessage: NonNullable<SessionUserActions["revert"]> = ({ messageID }) => revert.to(messageID)
   useComposerCommands()
   useSessionCommands({
     session: input.session,
@@ -178,7 +179,13 @@ export function createActiveSessionRegion(input: {
 
   return {
     actions: {
-      timeline: { revert: ({ messageID }) => revert.to(messageID), openAttachment } satisfies SessionUserActions,
+      timeline: {
+        get revert() {
+          if (input.session.data.isChild()) return
+          return revertMessage
+        },
+        openAttachment,
+      } satisfies SessionUserActions,
     },
     region: {
       centered: input.screen.centered,

packages/cli/src/acp/event.ts

@@ -76,6 +76,7 @@ export async function streamTurn(input: {
   readonly cwd: string
   readonly start: TurnStart
   readonly writeTextFile: boolean
+  readonly action?: boolean
   readonly submit: (signal: AbortSignal) => Promise<unknown>
   readonly control: TurnControl
   readonly childSessionUpdate?: (update: ChildSessionUpdate) => Promise<void>
@@ -345,6 +346,11 @@ export async function streamTurn(input: {
     await input.submit(control.admission.signal).catch((error) => {
       if (!control.cancelled) throw error
     })
+    if (input.action) {
+      streamController.abort()
+      await completed.catch(() => {})
+      return response(undefined, undefined, "succeeded", control.cancelled, undefined)
+    }
     if (control.cancelled) {
       await input.client.session.interrupt({ sessionID: input.sessionID }).catch(() => {})
       if (!started) {

packages/cli/src/acp/service.ts

@@ -326,6 +326,7 @@ export function make(input: { readonly client: OpenCodeClient; readonly connecti
         cwd: state.cwd,
         start: prepared.start,
         writeTextFile: capabilities.writeTextFile,
+        action: prepared.command !== undefined,
         control,
         connectionSignal: input.connection.signal,
         sessionSignal: state.abort.signal,
@@ -377,9 +378,8 @@ async function submitPrompt(client: OpenCodeClient, session: Attached, prompt: P
     return client.session.command(
       {
         sessionID: session.id,
-        id: prompt.start.id,
         command: prompt.command.name,
-        arguments: prompt.slash?.args,
+        text: prompt.slash?.args ?? "",
         files: prompt.files,
         delivery: "steer",
       },

packages/cli/src/services/updater-action.ts

@@ -1,5 +1,5 @@
 export type Policy = boolean | "notify"
-export type Action = "none" | "upgrade"
+export type Action = "none" | "notify" | "upgrade"
 
 const maximumComponent = "9007199254740991"
 const versionPattern =
@@ -12,7 +12,7 @@ export function action(current: string, latest: string, policy: Policy): Action
   if (!currentVersion || !latestVersion || sameRelease(currentVersion, latestVersion)) return "none"
   // Major upgrades are never installed automatically.
   if (currentVersion.major !== latestVersion.major) return "none"
-  return "upgrade"
+  return policy === "notify" ? "notify" : "upgrade"
 }
 
 function parseReleaseVersion(input: string) {

packages/cli/src/services/updater.test.ts

@@ -12,8 +12,12 @@ describe("updater", () => {
   test("automatically updates patches and minors", () => {
     expect(action("1.2.3", "1.2.4", true)).toBe("upgrade")
     expect(action("1.2.3", "1.3.0", true)).toBe("upgrade")
-    expect(action("1.2.3", "1.2.4", "notify")).toBe("upgrade")
-    expect(action("1.2.3", "1.3.0", "notify")).toBe("upgrade")
+  })
+
+  test("reports patches and minors without automatically installing them", () => {
+    expect(action("1.2.3", "1.2.4", "notify")).toBe("notify")
+    expect(action("1.2.3", "1.3.0", "notify")).toBe("notify")
+    expect(action("1.2.3", "1.2.3", "notify")).toBe("none")
   })
 
   test("skips when autoupdate is disabled", () => {

packages/cli/src/services/updater.ts

@@ -162,6 +162,8 @@ export const layer = Layer.effect(
           })
           const next = action(OPENCODE_VERSION, version, policy)
           if (next === "none") return yield* Effect.logInfo("update check done", { action: "up-to-date" })
+          if (next === "notify")
+            return yield* Effect.logInfo("OpenCode update available", { current: OPENCODE_VERSION, latest: version })
           const detected = yield* method()
           if (!detected) return yield* Effect.logWarning("automatic update skipped: installation method not found")
           yield* upgrade(detected, version)

packages/cli/test/acp/event-behavior.test.ts

@@ -601,6 +601,7 @@ describe("acp event behavior", () => {
       },
       onInterrupt({ sessionID, send }) {
         send(durableEvent("session.execution.interrupted", { sessionID, reason: "user" }))
+        return true
       },
     })
     const result = streamTurn({
@@ -624,7 +625,7 @@ describe("acp event behavior", () => {
       await withTimeout(submitted.promise, "cancel test prompt was not admitted")
       control.cancelled = true
       control.admission.abort()
-      await fixture.client.session.interrupt({ sessionID: "ses_cancel" })
+      expect(await fixture.client.session.interrupt({ sessionID: "ses_cancel" })).toEqual({ interrupted: true })
 
       const response = await withTimeout(result, "cancelled turn did not terminate")
       expect(response).toMatchObject({ stopReason: "cancelled" })

packages/cli/test/acp/event.test.ts

@@ -121,3 +121,42 @@ test("acp prompt resolves after ordered turn updates", async () => {
     controller.enqueue(encoder.encode(`data: ${JSON.stringify(event)}\n\n`))
   }
 })
+
+test("acp action resolves without prompt lifecycle events", async () => {
+  const encoder = new TextEncoder()
+  const server = Bun.serve({
+    port: 0,
+    fetch(request) {
+      if (new URL(request.url).pathname !== "/api/event") return new Response(null, { status: 404 })
+      return new Response(
+        new ReadableStream<Uint8Array>({
+          start(controller) {
+            controller.enqueue(encoder.encode(`data: ${JSON.stringify({ type: "server.connected", data: {} })}\n\n`))
+          },
+        }),
+        { headers: { "content-type": "text/event-stream" } },
+      )
+    },
+  })
+
+  try {
+    const response = await streamTurn({
+      client: OpenCode.make({ baseUrl: server.url.toString() }),
+      connection: {
+        sessionUpdate: async () => {},
+        requestPermission: async () => ({ outcome: { outcome: "cancelled" } }),
+      },
+      sessionID: "ses_test",
+      cwd: "/workspace",
+      start: { type: "input", id: "msg_action" },
+      writeTextFile: false,
+      action: true,
+      control: { cancelled: false, admission: new AbortController() },
+      submit: async () => {},
+    })
+
+    expect(response).toMatchObject({ stopReason: "end_turn" })
+  } finally {
+    await server.stop(true)
+  }
+})

packages/cli/test/acp/service-fixture.ts

@@ -87,7 +87,6 @@ export const planAgent = {
 export const reviewCommand = {
   name: "review",
   description: "Review changes",
-  template: "",
 } satisfies CommandInfo
 
 export const verifySkill = {

packages/cli/test/acp/service-usage.test.ts

@@ -12,13 +12,7 @@ describe("acp service prompt routing and usage", () => {
           return Response.json({ data: makeSession("ses_routes") })
         }
         if (request.method === "POST" && request.path === "/api/session/ses_routes/command") {
-          const id = requestID(request)
-          completeTurn(context, "ses_routes", {
-            id: `evt_${id}`,
-            type: "session.inbox.delivered",
-            data: { sessionID: "ses_routes", inboxID: id },
-          })
-          return Response.json({ data: {} })
+          return new Response(null, { status: 204 })
         }
         if (request.method === "POST" && request.path === "/api/session/ses_routes/skill") {
           const id = requestID(request)
@@ -65,9 +59,8 @@ describe("acp service prompt routing and usage", () => {
     const skill = fixture.requests.find((request) => request.path === "/api/session/ses_routes/skill")
     const compact = fixture.requests.find((request) => request.path === "/api/session/ses_routes/compact")
     expect(command?.body).toMatchObject({
-      id: expect.any(String),
       command: "review",
-      arguments: "now",
+      text: "now",
       files: [],
       delivery: "steer",
     })

packages/cli/test/acp/sse-fixture.ts

@@ -20,7 +20,7 @@ type FixtureOptions = {
   readonly onInterrupt?: (input: {
     readonly sessionID: string
     readonly send: (event: unknown) => void
-  }) => void | Promise<void>
+  }) => boolean | Promise<boolean>
   readonly onPermissionReply?: (input: {
     readonly sessionID: string
     readonly requestID: string
@@ -152,8 +152,9 @@ export function createSseFixture(options: FixtureOptions = {}) {
 
       const interrupt = /^\/api\/session\/([^/]+)\/interrupt$/.exec(url.pathname)
       if (interrupt?.[1]) {
-        await options.onInterrupt?.({ sessionID: decodeURIComponent(interrupt[1]), send })
-        return new Response(null, { status: 204 })
+        const interrupted =
+          (await options.onInterrupt?.({ sessionID: decodeURIComponent(interrupt[1]), send })) ?? false
+        return Response.json({ interrupted })
       }
 
       return new Response(null, { status: 404 })

packages/client/src/effect/api/api.ts

@@ -255,18 +255,14 @@ export type SessionPromptOperation<E = never> = (input: SessionPromptInput) => E
 
 export type SessionCommandInput = {
   readonly sessionID: Session.ID
-  readonly id?: SessionMessage.ID | undefined
   readonly command: string
-  readonly arguments?: string | undefined
-  readonly agent?: Agent.ID | undefined
-  readonly model?: Model.Ref | undefined
+  readonly text: string
   readonly files?: ReadonlyArray<PromptInput.FileAttachment> | undefined
   readonly agents?: ReadonlyArray<AgentAttachment> | undefined
   readonly skills?: ReadonlyArray<PromptInput.SkillAttachment> | undefined
   readonly delivery?: SessionInbox.Delivery | undefined
-  readonly resume?: boolean | undefined
 }
-export type SessionCommandOutput = SessionInbox.User
+export type SessionCommandOutput = void
 export type SessionCommandOperation<E = never> = (input: SessionCommandInput) => Effect.Effect<SessionCommandOutput, E>
 
 export type SessionSkillInput = {
@@ -1002,7 +998,7 @@ export type SessionLogOutput =
 export type SessionLogOperation<E = never> = (input: SessionLogInput) => Stream.Stream<SessionLogOutput, E>
 
 export type SessionInterruptInput = { readonly sessionID: Session.ID; readonly continue?: boolean | undefined }
-export type SessionInterruptOutput = void
+export type SessionInterruptOutput = { readonly interrupted: boolean }
 export type SessionInterruptOperation<E = never> = (
   input: SessionInterruptInput,
 ) => Effect.Effect<SessionInterruptOutput, E>
@@ -1112,11 +1108,7 @@ export interface ModelApi<E = never> {
   readonly default: ModelDefaultOperation<E>
 }
 
-export type GenerateTextInput = {
-  readonly location?: { readonly directory?: string | undefined; readonly workspace?: string | undefined } | undefined
-  readonly prompt: string
-  readonly model?: Model.Ref | undefined
-}
+export type GenerateTextInput = { readonly prompt: string; readonly model?: Model.Ref | undefined }
 export type GenerateTextOutput = { readonly text: string }
 export type GenerateTextOperation<E = never> = (input: GenerateTextInput) => Effect.Effect<GenerateTextOutput, E>
 
@@ -1699,6 +1691,23 @@ export interface WorktreeApi<E = never> {
   readonly refresh: WorktreeRefreshOperation<E>
 }
 
+export type WorkspaceCreateInput = { readonly id?: Workspace.ID | undefined; readonly provider: string }
+export type WorkspaceCreateOutput = Workspace.ID
+export type WorkspaceCreateOperation<E = never> = (
+  input: WorkspaceCreateInput,
+) => Effect.Effect<WorkspaceCreateOutput, E>
+
+export type WorkspaceDestroyInput = { readonly workspaceID: Workspace.ID }
+export type WorkspaceDestroyOutput = Workspace.DestroyResult
+export type WorkspaceDestroyOperation<E = never> = (
+  input: WorkspaceDestroyInput,
+) => Effect.Effect<WorkspaceDestroyOutput, E>
+
+export interface WorkspaceApi<E = never> {
+  readonly create: WorkspaceCreateOperation<E>
+  readonly destroy: WorkspaceDestroyOperation<E>
+}
+
 export type VcsGetInput = {
   readonly location?: { readonly directory?: string | undefined; readonly workspace?: string | undefined } | undefined
 }
@@ -1816,6 +1825,7 @@ export interface AppApi<E = never> {
   readonly shell: ShellApi<E>
   readonly reference: ReferenceApi<E>
   readonly worktree: WorktreeApi<E>
+  readonly workspace: WorkspaceApi<E>
   readonly vcs: VcsApi<E>
   readonly debug: DebugApi<E>
   readonly migration: MigrationApi<E>

packages/client/src/effect/generated/client.ts

@@ -214,6 +214,10 @@ import type {
   WorktreeRemoveOutput,
   WorktreeRefreshInput,
   WorktreeRefreshOutput,
+  WorkspaceCreateInput,
+  WorkspaceCreateOutput,
+  WorkspaceDestroyInput,
+  WorkspaceDestroyOutput,
   VcsGetInput,
   VcsGetOutput,
   VcsStatusInput,
@@ -440,21 +444,14 @@ const EndpointSessionCommand = (raw: RawClient["server.session"]) => (input: Ses
     raw["session.command"]({
       params: { sessionID: input["sessionID"] },
       payload: {
-        id: input["id"],
         command: input["command"],
-        arguments: input["arguments"],
-        agent: input["agent"],
-        model: input["model"],
+        text: input["text"],
         files: input["files"],
         agents: input["agents"],
         skills: input["skills"],
         delivery: input["delivery"],
-        resume: input["resume"],
       },
-    }).pipe(
-      Effect.mapError(mapClientError),
-      Effect.map((value) => value.data),
-    ),
+    }).pipe(Effect.mapError(mapClientError)),
   )
 
 const EndpointSessionSkill = (raw: RawClient["server.session"]) => (input: SessionSkillInput) =>
@@ -724,10 +721,7 @@ const adaptGroupModel = (raw: RawClient["server.model"]) => ({
 
 const EndpointGenerateText = (raw: RawClient["server.generate"]) => (input: GenerateTextInput) =>
   preserveEffect<GenerateTextOutput>()(
-    raw["generate.text"]({
-      query: { location: input["location"] },
-      payload: { prompt: input["prompt"], model: input["model"] },
-    }).pipe(
+    raw["generate.text"]({ payload: { prompt: input["prompt"], model: input["model"] } }).pipe(
       Effect.mapError(mapClientError),
       Effect.map((value) => value.data),
     ),
@@ -1278,6 +1272,24 @@ const adaptGroupWorktree = (raw: RawClient["server.worktree"]) => ({
   refresh: EndpointWorktreeRefresh(raw),
 })
 
+const EndpointWorkspaceCreate = (raw: RawClient["server.workspace"]) => (input: WorkspaceCreateInput) =>
+  preserveEffect<WorkspaceCreateOutput>()(
+    raw["workspace.create"]({ payload: { id: input["id"], provider: input["provider"] } }).pipe(
+      Effect.mapError(mapClientError),
+      Effect.map((value) => value.data),
+    ),
+  )
+
+const EndpointWorkspaceDestroy = (raw: RawClient["server.workspace"]) => (input: WorkspaceDestroyInput) =>
+  preserveEffect<WorkspaceDestroyOutput>()(
+    raw["workspace.destroy"]({ params: { workspaceID: input["workspaceID"] } }).pipe(Effect.mapError(mapClientError)),
+  )
+
+const adaptGroupWorkspace = (raw: RawClient["server.workspace"]) => ({
+  create: EndpointWorkspaceCreate(raw),
+  destroy: EndpointWorkspaceDestroy(raw),
+})
+
 const EndpointVcsGet = (raw: RawClient["server.vcs"]) => (input?: VcsGetInput) =>
   preserveEffect<VcsGetOutput>()(
     raw["vcs.get"]({ query: { location: input?.["location"] } }).pipe(Effect.mapError(mapClientError)),
@@ -1368,6 +1380,7 @@ const adaptClient = (raw: RawClient) => ({
   shell: adaptGroupShell(raw["server.shell"]),
   reference: adaptGroupReference(raw["server.reference"]),
   worktree: adaptGroupWorktree(raw["server.worktree"]),
+  workspace: adaptGroupWorkspace(raw["server.workspace"]),
   vcs: adaptGroupVcs(raw["server.vcs"]),
   debug: adaptGroupDebug(raw["server.debug"]),
   migration: adaptGroupMigration(raw["server.migration"]),

packages/client/src/promise/generated/client.ts

@@ -210,6 +210,10 @@ import type {
   WorktreeRemoveOutput,
   WorktreeRefreshInput,
   WorktreeRefreshOutput,
+  WorkspaceCreateInput,
+  WorkspaceCreateOutput,
+  WorkspaceDestroyInput,
+  WorkspaceDestroyOutput,
   VcsGetInput,
   VcsGetOutput,
   VcsStatusInput,
@@ -631,28 +635,24 @@ export function make(options: ClientOptions) {
           requestOptions,
         ).then((value) => value.data),
       command: (input: SessionCommandInput, requestOptions?: RequestOptions) =>
-        request<{ readonly data: SessionCommandOutput }>(
+        request<SessionCommandOutput>(
           {
             method: "POST",
             path: `/api/session/${encodeURIComponent(input.sessionID)}/command`,
             body: {
-              id: input["id"],
               command: input["command"],
-              arguments: input["arguments"],
-              agent: input["agent"],
-              model: input["model"],
+              text: input["text"],
               files: input["files"],
               agents: input["agents"],
               skills: input["skills"],
               delivery: input["delivery"],
-              resume: input["resume"],
             },
-            successStatus: 200,
-            declaredStatuses: [409, 400, 404, 500, 401],
-            empty: false,
+            successStatus: 204,
+            declaredStatuses: [404, 500, 400, 401],
+            empty: true,
           },
           requestOptions,
-        ).then((value) => value.data),
+        ),
       skill: (input: SessionSkillInput, requestOptions?: RequestOptions) =>
         request<SessionSkillOutput>(
           {
@@ -880,9 +880,9 @@ export function make(options: ClientOptions) {
             method: "POST",
             path: `/api/session/${encodeURIComponent(input.sessionID)}/interrupt`,
             query: { continue: input["continue"] },
-            successStatus: 204,
+            successStatus: 200,
             declaredStatuses: [404, 400, 401],
-            empty: true,
+            empty: false,
           },
           requestOptions,
         ),
@@ -979,7 +979,6 @@ export function make(options: ClientOptions) {
           {
             method: "POST",
             path: `/api/generate`,
-            query: { location: input["location"] },
             body: { prompt: input["prompt"], model: input["model"] },
             successStatus: 200,
             declaredStatuses: [400, 503, 401],
@@ -1770,6 +1769,31 @@ export function make(options: ClientOptions) {
           requestOptions,
         ),
     },
+    workspace: {
+      create: (input: WorkspaceCreateInput, requestOptions?: RequestOptions) =>
+        request<{ readonly data: WorkspaceCreateOutput }>(
+          {
+            method: "POST",
+            path: `/api/workspace`,
+            body: { id: input["id"], provider: input["provider"] },
+            successStatus: 200,
+            declaredStatuses: [409, 404, 401, 400],
+            empty: false,
+          },
+          requestOptions,
+        ).then((value) => value.data),
+      destroy: (input: WorkspaceDestroyInput, requestOptions?: RequestOptions) =>
+        request<WorkspaceDestroyOutput>(
+          {
+            method: "DELETE",
+            path: `/api/workspace/${encodeURIComponent(input.workspaceID)}`,
+            successStatus: 200,
+            declaredStatuses: [500, 401, 400],
+            empty: false,
+          },
+          requestOptions,
+        ),
+    },
     vcs: {
       get: (input?: VcsGetInput, requestOptions?: RequestOptions) =>
         request<VcsGetOutput>(

packages/client/src/promise/generated/types.ts

@@ -176,6 +176,8 @@ export type ToolFileContent1 = { type: "file"; uri: string; mime: string; name?:
 
 export type EventLogSynced = { type: "log.synced"; aggregateID: string; seq?: number }
 
+export type SessionInterruptResponse = { interrupted: boolean }
+
 export type ModelReasoningField = "reasoning" | "reasoning_content" | "reasoning_text" | (string & {})
 
 export type ModelMaxTokensField = "max_completion_tokens" | "max_tokens"
@@ -311,6 +313,8 @@ export type PermissionSavedInfo = { id: string; projectID: string; action: strin
 
 export type FileSystemEntry = { path: string; type: "file" | "directory" }
 
+export type CommandInfo = { name: string; description?: string }
+
 export type SkillInfo = {
   id: string
   name: string
@@ -378,6 +382,8 @@ export type WorktreeDirectory = { directory: string; strategy?: string }
 
 export type WorktreeInfo = { directory: string }
 
+export type WorkspaceDestroyResult = { destroyed: boolean }
+
 export type VcsBranch = { current?: string; default?: string }
 
 export type VcsFileStatus = {
@@ -391,15 +397,6 @@ export type WebSearchProvider = { id: string; name: string }
 
 export type WebSearchResult = { url: string; title?: string; content?: string; time: { published?: number } }
 
-export type CommandInfo = {
-  name: string
-  template: string
-  description?: string
-  agent?: string
-  model?: ModelRef
-  subtask?: boolean
-}
-
 export type ProviderRequest = {
   settings: ProviderSettings
   headers: { [x: string]: string }
@@ -2220,13 +2217,13 @@ export type CommandNotFoundError = {
 export const isCommandNotFoundError = (value: unknown): value is CommandNotFoundError =>
   typeof value === "object" && value !== null && "_tag" in value && value["_tag"] === "CommandNotFoundError"
 
-export type CommandEvaluationError = {
-  readonly _tag: "CommandEvaluationError"
+export type CommandExecutionError = {
+  readonly _tag: "CommandExecutionError"
   readonly command: string
   readonly message: string
 }
-export const isCommandEvaluationError = (value: unknown): value is CommandEvaluationError =>
-  typeof value === "object" && value !== null && "_tag" in value && value["_tag"] === "CommandEvaluationError"
+export const isCommandExecutionError = (value: unknown): value is CommandExecutionError =>
+  typeof value === "object" && value !== null && "_tag" in value && value["_tag"] === "CommandExecutionError"
 
 export type SkillNotFoundError = {
   readonly _tag: "SkillNotFoundError"
@@ -3637,35 +3634,9 @@ export type SessionPromptOutput = { data: SessionInboxUser }["data"]
 
 export type SessionCommandInput = {
   readonly sessionID: { readonly sessionID: string }["sessionID"]
-  readonly id?: {
-    readonly id?: string | null
-    readonly command: string
-    readonly arguments?: string | null
-    readonly agent?: string | null
-    readonly model?: { readonly id: string; readonly providerID: string; readonly variant?: string } | null
-    readonly files?: ReadonlyArray<{
-      readonly uri: string
-      readonly name?: string
-      readonly description?: string
-      readonly mention?: { readonly start: number; readonly end: number; readonly text: string }
-    }>
-    readonly agents?: ReadonlyArray<{
-      readonly name: string
-      readonly mention?: { readonly start: number; readonly end: number; readonly text: string }
-    }>
-    readonly skills?: ReadonlyArray<{
-      readonly id: string
-      readonly mention?: { readonly start: number; readonly end: number; readonly text: string }
-    }>
-    readonly delivery?: ("steer" | "queue") | null
-    readonly resume?: boolean | null
-  }["id"]
   readonly command: {
-    readonly id?: string | null
     readonly command: string
-    readonly arguments?: string | null
-    readonly agent?: string | null
-    readonly model?: { readonly id: string; readonly providerID: string; readonly variant?: string } | null
+    readonly text: string
     readonly files?: ReadonlyArray<{
       readonly uri: string
       readonly name?: string
@@ -3681,14 +3652,10 @@ export type SessionCommandInput = {
       readonly mention?: { readonly start: number; readonly end: number; readonly text: string }
     }>
     readonly delivery?: ("steer" | "queue") | null
-    readonly resume?: boolean | null
   }["command"]
-  readonly arguments?: {
-    readonly id?: string | null
+  readonly text: {
     readonly command: string
-    readonly arguments?: string | null
-    readonly agent?: string | null
-    readonly model?: { readonly id: string; readonly providerID: string; readonly variant?: string } | null
+    readonly text: string
     readonly files?: ReadonlyArray<{
       readonly uri: string
       readonly name?: string
@@ -3704,60 +3671,10 @@ export type SessionCommandInput = {
       readonly mention?: { readonly start: number; readonly end: number; readonly text: string }
     }>
     readonly delivery?: ("steer" | "queue") | null
-    readonly resume?: boolean | null
-  }["arguments"]
-  readonly agent?: {
-    readonly id?: string | null
-    readonly command: string
-    readonly arguments?: string | null
-    readonly agent?: string | null
-    readonly model?: { readonly id: string; readonly providerID: string; readonly variant?: string } | null
-    readonly files?: ReadonlyArray<{
-      readonly uri: string
-      readonly name?: string
-      readonly description?: string
-      readonly mention?: { readonly start: number; readonly end: number; readonly text: string }
-    }>
-    readonly agents?: ReadonlyArray<{
-      readonly name: string
-      readonly mention?: { readonly start: number; readonly end: number; readonly text: string }
-    }>
-    readonly skills?: ReadonlyArray<{
-      readonly id: string
-      readonly mention?: { readonly start: number; readonly end: number; readonly text: string }
-    }>
-    readonly delivery?: ("steer" | "queue") | null
-    readonly resume?: boolean | null
-  }["agent"]
-  readonly model?: {
-    readonly id?: string | null
-    readonly command: string
-    readonly arguments?: string | null
-    readonly agent?: string | null
-    readonly model?: { readonly id: string; readonly providerID: string; readonly variant?: string } | null
-    readonly files?: ReadonlyArray<{
-      readonly uri: string
-      readonly name?: string
-      readonly description?: string
-      readonly mention?: { readonly start: number; readonly end: number; readonly text: string }
-    }>
-    readonly agents?: ReadonlyArray<{
-      readonly name: string
-      readonly mention?: { readonly start: number; readonly end: number; readonly text: string }
-    }>
-    readonly skills?: ReadonlyArray<{
-      readonly id: string
-      readonly mention?: { readonly start: number; readonly end: number; readonly text: string }
-    }>
-    readonly delivery?: ("steer" | "queue") | null
-    readonly resume?: boolean | null
-  }["model"]
+  }["text"]
   readonly files?: {
-    readonly id?: string | null
     readonly command: string
-    readonly arguments?: string | null
-    readonly agent?: string | null
-    readonly model?: { readonly id: string; readonly providerID: string; readonly variant?: string } | null
+    readonly text: string
     readonly files?: ReadonlyArray<{
       readonly uri: string
       readonly name?: string
@@ -3773,14 +3690,10 @@ export type SessionCommandInput = {
       readonly mention?: { readonly start: number; readonly end: number; readonly text: string }
     }>
     readonly delivery?: ("steer" | "queue") | null
-    readonly resume?: boolean | null
   }["files"]
   readonly agents?: {
-    readonly id?: string | null
     readonly command: string
-    readonly arguments?: string | null
-    readonly agent?: string | null
-    readonly model?: { readonly id: string; readonly providerID: string; readonly variant?: string } | null
+    readonly text: string
     readonly files?: ReadonlyArray<{
       readonly uri: string
       readonly name?: string
@@ -3796,14 +3709,10 @@ export type SessionCommandInput = {
       readonly mention?: { readonly start: number; readonly end: number; readonly text: string }
     }>
     readonly delivery?: ("steer" | "queue") | null
-    readonly resume?: boolean | null
   }["agents"]
   readonly skills?: {
-    readonly id?: string | null
     readonly command: string
-    readonly arguments?: string | null
-    readonly agent?: string | null
-    readonly model?: { readonly id: string; readonly providerID: string; readonly variant?: string } | null
+    readonly text: string
     readonly files?: ReadonlyArray<{
       readonly uri: string
       readonly name?: string
@@ -3819,14 +3728,10 @@ export type SessionCommandInput = {
       readonly mention?: { readonly start: number; readonly end: number; readonly text: string }
     }>
     readonly delivery?: ("steer" | "queue") | null
-    readonly resume?: boolean | null
   }["skills"]
   readonly delivery?: {
-    readonly id?: string | null
     readonly command: string
-    readonly arguments?: string | null
-    readonly agent?: string | null
-    readonly model?: { readonly id: string; readonly providerID: string; readonly variant?: string } | null
+    readonly text: string
     readonly files?: ReadonlyArray<{
       readonly uri: string
       readonly name?: string
@@ -3842,34 +3747,10 @@ export type SessionCommandInput = {
       readonly mention?: { readonly start: number; readonly end: number; readonly text: string }
     }>
     readonly delivery?: ("steer" | "queue") | null
-    readonly resume?: boolean | null
   }["delivery"]
-  readonly resume?: {
-    readonly id?: string | null
-    readonly command: string
-    readonly arguments?: string | null
-    readonly agent?: string | null
-    readonly model?: { readonly id: string; readonly providerID: string; readonly variant?: string } | null
-    readonly files?: ReadonlyArray<{
-      readonly uri: string
-      readonly name?: string
-      readonly description?: string
-      readonly mention?: { readonly start: number; readonly end: number; readonly text: string }
-    }>
-    readonly agents?: ReadonlyArray<{
-      readonly name: string
-      readonly mention?: { readonly start: number; readonly end: number; readonly text: string }
-    }>
-    readonly skills?: ReadonlyArray<{
-      readonly id: string
-      readonly mention?: { readonly start: number; readonly end: number; readonly text: string }
-    }>
-    readonly delivery?: ("steer" | "queue") | null
-    readonly resume?: boolean | null
-  }["resume"]
 }
 
-export type SessionCommandOutput = { data: SessionInboxUser }["data"]
+export type SessionCommandOutput = void
 
 export type SessionSkillInput = {
   readonly sessionID: { readonly sessionID: string }["sessionID"]
@@ -4053,7 +3934,7 @@ export type SessionInterruptInput = {
   readonly continue?: { readonly continue?: boolean | undefined }["continue"]
 }
 
-export type SessionInterruptOutput = void
+export type SessionInterruptOutput = SessionInterruptResponse
 
 export type SessionBackgroundInput = { readonly sessionID: { readonly sessionID: string }["sessionID"] }
 
@@ -4124,9 +4005,6 @@ export type ModelDefaultOutput = {
 }
 
 export type GenerateTextInput = {
-  readonly location?: {
-    readonly location?: { readonly directory?: string | undefined; readonly workspace?: string | undefined } | undefined
-  }["location"]
   readonly prompt: {
     readonly prompt: string
     readonly model?: { readonly id: string; readonly providerID: string; readonly variant?: string } | null
@@ -5752,6 +5630,17 @@ export type WorktreeRefreshInput = { readonly projectID: { readonly projectID: s
 
 export type WorktreeRefreshOutput = void
 
+export type WorkspaceCreateInput = {
+  readonly id?: { readonly id?: string | undefined; readonly provider: string }["id"]
+  readonly provider: { readonly id?: string | undefined; readonly provider: string }["provider"]
+}
+
+export type WorkspaceCreateOutput = { data: string }["data"]
+
+export type WorkspaceDestroyInput = { readonly workspaceID: { readonly workspaceID: string }["workspaceID"] }
+
+export type WorkspaceDestroyOutput = WorkspaceDestroyResult
+
 export type VcsGetInput = {
   readonly location?: {
     readonly location?: { readonly directory?: string | undefined; readonly workspace?: string | undefined } | undefined

packages/client/test/effect.test.ts

@@ -172,7 +172,14 @@ test("session methods retain decoded Effect inputs and outputs", async () => {
       return Effect.succeed(HttpClientResponse.fromWeb(request, Response.json(session)))
     }
     if (request.method === "POST") {
-      return Effect.succeed(HttpClientResponse.fromWeb(request, new Response(null, { status: 204 })))
+      return Effect.succeed(
+        HttpClientResponse.fromWeb(
+          request,
+          request.url.includes("/interrupt")
+            ? Response.json({ interrupted: true })
+            : new Response(null, { status: 204 }),
+        ),
+      )
     }
     return Effect.succeed(
       HttpClientResponse.fromWeb(request, Response.json({ data: [session.data], cursor: { next: "next" } })),
@@ -202,12 +209,12 @@ test("session methods retain decoded Effect inputs and outputs", async () => {
     const log = yield* client.session
       .log({ sessionID: Session.ID.make("ses_test"), after: Event.Seq.make(0) })
       .pipe(Stream.runCollect)
-    yield* client.session.interrupt({ sessionID: Session.ID.make("ses_test") })
+    const interrupted = yield* client.session.interrupt({ sessionID: Session.ID.make("ses_test") })
     const message = yield* client.session.message({
       sessionID: Session.ID.make("ses_test"),
       messageID: SessionMessage.ID.make("msg_model"),
     })
-    return { page, active, created, admitted, context, log, message }
+    return { page, active, created, admitted, context, log, interrupted, message }
   }).pipe(Effect.provideService(HttpClient.HttpClient, httpClient), Effect.runPromise)
 
   const listed = result.page.data[0]
@@ -216,6 +223,7 @@ test("session methods retain decoded Effect inputs and outputs", async () => {
   expect(DateTime.toEpochMillis(listed.time.idle)).toBe(1_717_171_717_002)
   expect(DateTime.toEpochMillis(listed.time.viewed)).toBe(1_717_171_717_001)
   expect(result.active).toEqual({ ses_test: { type: "running" } })
+  expect(result.interrupted).toEqual({ interrupted: true })
   expect(Object.getPrototypeOf(result.page.data[0])).toBe(Object.prototype)
   expect(Object.getPrototypeOf(result.created)).toBe(Object.prototype)
   expect(result.created.id).toBe("ses_test")

packages/client/test/promise.test.ts

@@ -30,6 +30,7 @@ test("exposes every standard HTTP API group", () => {
     "question",
     "reference",
     "worktree",
+    "workspace",
     "vcs",
     "debug",
     "migration",
@@ -81,6 +82,21 @@ test("config.get returns ordered config entries for a location", async () => {
   expect(request?.url).toBe("http://localhost:3000/api/config?location%5Bdirectory%5D=%2Ftmp%2Fproject")
 })
 
+test("generate.text uses the locationless public contract", async () => {
+  let request: Request | undefined
+  const client = OpenCode.make({
+    baseUrl: "http://localhost:3000",
+    fetch: async (input, init) => {
+      request = input instanceof Request ? input : new Request(input, init)
+      return Response.json({ data: { text: "pong" } })
+    },
+  })
+
+  expect(await client.generate.text({ prompt: "ping" })).toEqual({ text: "pong" })
+  expect(request?.url).toBe("http://localhost:3000/api/generate")
+  expect(await request?.json()).toEqual({ prompt: "ping" })
+})
+
 test("websearch.query uses the public HTTP contract", async () => {
   let request: Request | undefined
   const client = OpenCode.make({
@@ -280,6 +296,21 @@ test("worktree methods use the global project contract", async () => {
   expect(await requests[2]?.json()).toEqual({ directory: "/tmp/worktrees/api", force: false })
 })
 
+test("workspace.destroy returns the transition result", async () => {
+  let request: Request | undefined
+  const client = OpenCode.make({
+    baseUrl: "http://localhost:3000",
+    fetch: async (input, init) => {
+      request = input instanceof Request ? input : new Request(input, init)
+      return Response.json({ destroyed: false })
+    },
+  })
+
+  expect(await client.workspace.destroy({ workspaceID: "wrk_missing" })).toEqual({ destroyed: false })
+  expect(request?.method).toBe("DELETE")
+  expect(request?.url).toBe("http://localhost:3000/api/workspace/wrk_missing")
+})
+
 test("shell list and remove use the public HTTP contract", async () => {
   const requests: Array<{ method: string; url: string }> = []
   const shell = {
@@ -516,6 +547,7 @@ test("session methods use the public HTTP contract", async () => {
       if (url.includes("/message/")) return Response.json({ data: modelSwitchedMessage })
       if (url.endsWith("/api/session/active")) return Response.json({ data: { ses_test: { type: "running" } } })
       if (init?.method === "POST" && url.endsWith("/api/session")) return Response.json(session)
+      if (url.includes("/interrupt")) return Response.json({ interrupted: true })
       if (init?.method === "POST") return new Response(null, { status: 204 })
       return Response.json({ data: [session.data], cursor: { next: "next" } })
     },
@@ -547,7 +579,7 @@ test("session methods use the public HTTP contract", async () => {
   const context = await client.session.context({ sessionID: "ses_test" })
   const log = []
   for await (const item of client.session.log({ sessionID: "ses_test", after: 0 })) log.push(item)
-  await client.session.interrupt({ sessionID: "ses_test", continue: true })
+  const interrupted = await client.session.interrupt({ sessionID: "ses_test", continue: true })
   const message = await client.session.message({ sessionID: "ses_test", messageID: "msg_model" })
 
   expect(page.cursor.next).toBe("next")
@@ -556,6 +588,7 @@ test("session methods use the public HTTP contract", async () => {
   expect(created.id).toBe("ses_test")
   expect(admitted.id).toBe("msg_test")
   expect(generated.text).toBe("A transient answer")
+  expect(interrupted).toEqual({ interrupted: true })
   expect(synthetic).toMatchObject({ type: "synthetic", data: { text: "Completed" }, delivery: "queue" })
   expect(context).toEqual([])
   expect(log).toEqual([modelSwitchedEvent, synced])

packages/console/app/src/routes/legal/privacy-policy/index.tsx

@@ -237,9 +237,8 @@ export default function PrivacyPolicy() {
                       </td>
                       <td>
                         <ul>
-                          <li>Providing, Customizing and Improving the Services</li>
-                          <li>Marketing the Services</li>
-                          <li>Corresponding with You</li>
+                          <li>Passing through to upstream provider to provide services</li>
+                          <li>Not stored</li>
                         </ul>
                       </td>
                       <td>

packages/core/src/command.ts

@@ -1,26 +1,32 @@
 export * as Command from "./command.js"
 
-import { makeLocationNode } from "@opencode-ai/util/effect/app-node"
-import { Context, Effect, Layer, Schema, Types } from "effect"
 import { Command } from "@opencode-ai/schema/command"
-import { State } from "./state.js"
-import { MCP } from "./mcp/index.js"
+import type { PromptInput } from "@opencode-ai/schema/prompt-input"
+import type { Session } from "@opencode-ai/schema/session"
+import type { SessionInbox } from "@opencode-ai/schema/session-inbox"
+import { makeLocationNode } from "@opencode-ai/util/effect/app-node"
+import { Context, Effect, Layer, Schema } from "effect"
 import { Bus } from "./bus.js"
-import { AppProcess } from "@opencode-ai/util/process"
-import { ChildProcess } from "effect/unstable/process"
-import { Location } from "./location.js"
-import { ShellSelect } from "./shell/select.js"
+import { State } from "./state.js"
 
 export const Info = Command.Info
 export type Info = Command.Info
 export { Event } from "@opencode-ai/schema/command"
 
-export type Evaluation = {
-  readonly text: string
+export interface Invocation {
+  readonly sessionID: Session.ID
+  readonly prompt: PromptInput.Prompt
+  readonly delivery: SessionInbox.Delivery
 }
 
-export type Data = {
-  commands: Map<string, Types.DeepMutable<Info>>
+export interface Definition {
+  readonly name: string
+  readonly description?: string
+  readonly execute: (input: Invocation) => Effect.Effect<void, unknown>
+}
+
+export type Draft = {
+  add: (definition: Definition) => void
 }
 
 export class NotFoundError extends Schema.TaggedError<NotFoundError>()("Command.NotFoundError", {
@@ -28,234 +34,73 @@ export class NotFoundError extends Schema.TaggedError<NotFoundError>()("Command.
   message: Schema.String,
 }) {}
 
-export class EvaluationError extends Schema.TaggedError<EvaluationError>()("Command.EvaluationError", {
+export class ExecutionError extends Schema.TaggedError<ExecutionError>()("Command.ExecutionError", {
   command: Schema.String,
   message: Schema.String,
 }) {}
 
-export type Draft = {
-  list: () => readonly Info[]
-  get: (name: string) => Info | undefined
-  update: (name: string, update: (command: Types.DeepMutable<Info>) => void) => void
-  remove: (name: string) => void
-}
-
 export interface Interface extends State.Transformable<Draft> {
   readonly get: (name: string) => Effect.Effect<Info | undefined>
   readonly list: () => Effect.Effect<Info[]>
-  readonly evaluate: (input: {
+  readonly execute: (input: {
     readonly name: string
-    readonly arguments?: string
-  }) => Effect.Effect<Evaluation, NotFoundError | EvaluationError>
+    readonly invocation: Invocation
+  }) => Effect.Effect<void, NotFoundError | ExecutionError>
 }
 
 export class Service extends Context.Service<Service, Interface>()("@opencode/Command") {}
 
-const layer = () =>
-  Layer.effect(
-    Service,
-    Effect.gen(function* () {
-      const mcp = yield* MCP.Service
-      const bus = yield* Bus.Service
-      const processes = yield* AppProcess.Service
-      const location = yield* Location.Service
-      const shell = yield* ShellSelect.Service
-      const state = State.create<Data, Draft>({
-        name: "command",
-        initial: () => ({ commands: new Map() }),
-        draft: (draft) => ({
-          list: () => Array.from(draft.commands.values()) as Info[],
-          get: (name) => draft.commands.get(name),
-          update: (name, update) => {
-            const current = draft.commands.get(name) ?? ({ name, template: "" } as Types.DeepMutable<Info>)
-            if (!draft.commands.has(name)) draft.commands.set(name, current)
-            update(current)
-            current.name = name
-          },
-          remove: (name) => {
-            draft.commands.delete(name)
-          },
-        }),
-        finalize: () => bus.publish(Command.Event.Updated, {}).pipe(Effect.asVoid),
-      })
-      const staticCommand = (name: string) => state.get().commands.get(name) as Info | undefined
-      const mcpCommands = Effect.fnUntraced(function* () {
-        return (yield* mcp.prompts()).map((prompt) =>
-          Info.make({
-            name: mcpCommandName(prompt.server, prompt.name),
-            template: "",
-            description: prompt.description,
-          }),
-        )
+export const layer = Layer.effect(
+  Service,
+  Effect.gen(function* () {
+    const bus = yield* Bus.Service
+    const state = State.create<Map<string, Definition>, Draft>({
+      name: "command",
+      initial: () => new Map(),
+      draft: (draft) => ({
+        add: (definition) => draft.set(definition.name, definition),
+      }),
+      finalize: () => bus.publish(Command.Event.Updated, {}).pipe(Effect.asVoid),
+    })
+    const info = (definition: Definition) =>
+      Info.make({
+        name: definition.name,
+        description: definition.description,
       })
 
-      return Service.of({
-        reload: state.reload,
-        transform: state.transform,
-        get: Effect.fn("Command.get")(function* (name) {
-          const command = staticCommand(name)
-          if (command) return command
-          return (yield* mcpCommands()).find((command) => command.name === name)
+    return Service.of({
+      reload: state.reload,
+      transform: state.transform,
+      get: Effect.fn("Command.get")((name) =>
+        Effect.sync(() => {
+          const definition = state.get().get(name)
+          return definition ? info(definition) : undefined
         }),
-        list: Effect.fn("Command.list")(function* () {
-          const commands = Array.from(state.get().commands.values()) as Info[]
-          const names = new Set(commands.map((command) => command.name))
-          return [...commands, ...(yield* mcpCommands()).filter((command) => !names.has(command.name))]
-        }),
-        evaluate: Effect.fn("Command.evaluate")(function* (input) {
-          const command = staticCommand(input.name)
-          if (command)
-            return yield* evaluateTemplate(input.name, command.template, input.arguments ?? "", {
-              location,
-              processes,
-              shell,
-            })
-
-          const prompt = (yield* mcp.prompts()).find(
-            (prompt) => mcpCommandName(prompt.server, prompt.name) === input.name,
-          )
-          if (!prompt)
-            return yield* new NotFoundError({ command: input.name, message: `Command not found: ${input.name}` })
-          const result = yield* mcp
-            .prompt({
-              server: prompt.server,
-              name: prompt.name,
-              args: Object.fromEntries(
-                (prompt.arguments ?? []).map((argument, index) => [
-                  argument.name,
-                  parseArguments(input.arguments ?? "")[index] ?? "",
-                ]),
-              ),
-            })
-            .pipe(
-              Effect.catchTag("MCP.NotFoundError", () =>
-                Effect.fail(
-                  new EvaluationError({
-                    command: input.name,
-                    message: `MCP server could not be found while evaluating prompt: ${prompt.server}`,
-                  }),
-                ),
-              ),
-            )
-          if (!result)
-            return yield* new EvaluationError({
-              command: input.name,
-              message: `MCP prompt could not be evaluated: ${prompt.server}:${prompt.name}`,
-            })
-          return {
-            text: result.messages
-              .map((message) => promptMessageText(message.content))
-              .join("\n")
-              .trim(),
-          }
-        }),
-      })
-    }),
-  )
-
-function evaluateTemplate(
-  command: string,
-  template: string,
-  input: string,
-  services: {
-    readonly location: Location.Info
-    readonly processes: AppProcess.Interface
-    readonly shell: ShellSelect.Interface
-  },
-) {
-  return Effect.gen(function* () {
-    const expanded = evaluateArguments(template, input)
-    return { text: yield* evaluateShell(command, expanded, services) }
-  })
-}
-
-function evaluateArguments(template: string, input: string) {
-  const args = parseArguments(input)
-  const placeholders = template.match(placeholderRegex) ?? []
-  const last = Math.max(0, ...placeholders.map((item) => Number(item.slice(1))))
-  const expanded = template.replaceAll(placeholderRegex, (_, index) => {
-    const position = Number(index)
-    const argIndex = position - 1
-    if (argIndex >= args.length) return ""
-    if (position === last) return args.slice(argIndex).join(" ")
-    return args[argIndex]
-  })
-  const withArguments = expanded.replaceAll("$ARGUMENTS", input)
-  if (placeholders.length === 0 && !template.includes("$ARGUMENTS") && input.trim())
-    return `${withArguments}\n\n${input}`.trim()
-  return withArguments.trim()
-}
-
-const evaluateShell = Effect.fnUntraced(function* (
-  command: string,
-  text: string,
-  services: {
-    readonly location: Location.Info
-    readonly processes: AppProcess.Interface
-    readonly shell: ShellSelect.Interface
-  },
-) {
-  const matches = Array.from(text.matchAll(shellRegex))
-  if (matches.length === 0) return text
-  const shell = yield* services.shell.preferred()
-  const outputs = yield* Effect.forEach(
-    matches,
-    (match) => {
-      const source = match[1] ?? ""
-      return services.processes
-        .run(
-          ChildProcess.make(shell, ShellSelect.args(shell, source), {
-            cwd: services.location.directory,
-            stdin: "ignore",
-          }),
-          {
-            combineOutput: true,
-          },
+      ),
+      list: Effect.fn("Command.list")(() => Effect.sync(() => Array.from(state.get().values(), info))),
+      execute: Effect.fn("Command.execute")(function* (input) {
+        const definition = state.get().get(input.name)
+        if (!definition)
+          return yield* new NotFoundError({ command: input.name, message: `Command not found: ${input.name}` })
+        return yield* definition.execute(input.invocation).pipe(
+          Effect.tapError((error) => Effect.logError("command execution failed", { command: input.name, error })),
+          Effect.mapError((error) => new ExecutionError({ command: input.name, message: errorMessage(error) })),
         )
-        .pipe(
-          Effect.map((result) => (result.output ?? Buffer.concat([result.stdout, result.stderr])).toString("utf8")),
-          Effect.mapError(
-            (error) =>
-              new EvaluationError({
-                command,
-                message: `Shell interpolation failed for ${JSON.stringify(source)}: ${error.message}`,
-              }),
-          ),
-        )
-    },
-    { concurrency: 2 },
-  )
-  const iterator = outputs[Symbol.iterator]()
-  return text.replace(shellRegex, () => iterator.next().value ?? "")
-})
-
-function parseArguments(input: string) {
-  return (input.match(argsRegex) ?? []).map((arg) => arg.replace(quoteTrimRegex, ""))
-}
-
-function promptMessageText(content: unknown) {
-  if (typeof content === "string") return content
-  if (!content || typeof content !== "object") return ""
-  if (!("type" in content) || content.type !== "text") return ""
-  if (!("text" in content) || typeof content.text !== "string") return ""
-  return content.text
-}
-
-function mcpCommandName(server: string, prompt: string) {
-  return `${sanitize(server)}:${sanitize(prompt)}`
-}
-
-function sanitize(value: string) {
-  return value.replace(/[^a-zA-Z0-9_-]/g, "_")
-}
-
-const argsRegex = /(?:\[Image\s+\d+\]|"[^"]*"|'[^']*'|[^\s"']+)/gi
-const placeholderRegex = /\$(\d+)/g
-const quoteTrimRegex = /^["']|["']$/g
-const shellRegex = /!`([^`]+)`/g
+      }),
+    })
+  }),
+)
 
 export const node = makeLocationNode({
   service: Service,
-  layer: layer(),
-  deps: [MCP.node, Bus.node, AppProcess.node, Location.node, ShellSelect.node],
+  layer,
+  deps: [Bus.node],
 })
+
+function errorMessage(error: unknown) {
+  if (error instanceof Error) return error.message
+  if (typeof error === "string") return error
+  if (error && typeof error === "object" && "message" in error && typeof error.message === "string")
+    return error.message
+  return "Command execution failed"
+}

packages/core/src/config/plugin/command.ts

@@ -1,12 +1,18 @@
 export * as ConfigCommandPlugin from "./command.js"
 
 import { define } from "@opencode-ai/plugin/effect/plugin"
+import { Agent } from "@opencode-ai/schema/agent"
 import { Info, type Entry } from "@opencode-ai/schema/config"
 import { ConfigCommand } from "@opencode-ai/schema/config/command"
+import { Model } from "@opencode-ai/schema/model"
+import { Provider } from "@opencode-ai/schema/provider"
+import { AppProcess } from "@opencode-ai/util/process"
 import path from "path"
 import { Effect, Option, Schema, Stream } from "effect"
-import { Command } from "../../command.js"
+import { ChildProcess } from "effect/unstable/process"
 import { Config } from "../../config.js"
+import { Location } from "../../location.js"
+import { ShellSelect } from "../../shell/select.js"
 import { FSUtil } from "@opencode-ai/util/fs-util"
 import { ConfigMarkdown } from "../markdown.js"
 
@@ -23,6 +29,9 @@ export const Plugin = define({
       const commands = yield* loadDirectory(fs, entry.path)
       return [{ commands: Object.fromEntries(commands.map((command) => [command.name, command.info])) }]
     })
+    const location = yield* Location.Service
+    const processes = yield* AppProcess.Service
+    const shell = yield* ShellSelect.Service
     const load = Effect.fn("ConfigCommandPlugin.load")(function* () {
       return yield* Effect.forEach(yield* config.entries(), loadEntry).pipe(Effect.map((documents) => documents.flat()))
     })
@@ -51,17 +60,41 @@ export const Plugin = define({
     yield* ctx.command.transform((draft) => {
       for (const document of loaded.documents) {
         for (const [name, command] of Object.entries(document.commands ?? {})) {
-          draft.update(name, (item) => {
-            item.template = command.template
-            if (command.description !== undefined) item.description = command.description
-            if (command.agent !== undefined) item.agent = command.agent
-            if (command.model !== undefined)
-              item.model = {
-                id: command.model.model,
-                providerID: command.model.providerID,
-                ...(command.model.variant === undefined ? {} : { variant: command.model.variant }),
-              }
-            if (command.subtask !== undefined) item.subtask = command.subtask
+          draft.add({
+            name,
+            description: command.description,
+            execute: (input) =>
+              Effect.gen(function* () {
+                const agent = command.agent === undefined ? undefined : Agent.ID.make(command.agent)
+                const commandAgent = yield* Effect.gen(function* () {
+                  if (agent === undefined) return
+                  const session = yield* ctx.session.get({ sessionID: input.sessionID })
+                  if (session.agent !== agent) yield* ctx.session.switchAgent({ sessionID: input.sessionID, agent })
+                  return (yield* ctx.agent.get({ agentID: agent })).data
+                })
+                const model =
+                  command.model === undefined
+                    ? commandAgent?.model
+                    : {
+                        id: Model.ID.make(command.model.model),
+                        providerID: Provider.ID.make(command.model.providerID),
+                        ...(command.model.variant === undefined
+                          ? {}
+                          : { variant: Model.VariantID.make(command.model.variant) }),
+                      }
+                if (model !== undefined) yield* ctx.session.switchModel({ sessionID: input.sessionID, model })
+                yield* ctx.session.prompt({
+                  ...input.prompt,
+                  sessionID: input.sessionID,
+                  text: yield* evaluateTemplate(command.template, input.prompt.text, {
+                    config,
+                    location,
+                    processes,
+                    shell,
+                  }),
+                  delivery: input.delivery,
+                })
+              }).pipe(Effect.asVoid),
           })
         }
       }
@@ -114,3 +147,67 @@ function decode(directory: string, filepath: string, content: string) {
     info,
   }
 }
+
+function evaluateTemplate(
+  template: string,
+  input: string,
+  services: {
+    readonly config: Config.Interface
+    readonly location: Location.Info
+    readonly processes: AppProcess.Interface
+    readonly shell: ShellSelect.Interface
+  },
+) {
+  return Effect.gen(function* () {
+    const args = parseArguments(input)
+    const placeholders = template.match(placeholderRegex) ?? []
+    const last = Math.max(0, ...placeholders.map((item) => Number(item.slice(1))))
+    const expanded = template.replaceAll(placeholderRegex, (_, index) => {
+      const position = Number(index)
+      const argIndex = position - 1
+      if (argIndex >= args.length) return ""
+      if (position === last) return args.slice(argIndex).join(" ")
+      return args[argIndex]
+    })
+    const withArguments = expanded.replaceAll("$ARGUMENTS", input)
+    const text =
+      placeholders.length === 0 && !template.includes("$ARGUMENTS") && input.trim()
+        ? `${withArguments}\n\n${input}`.trim()
+        : withArguments.trim()
+    const matches = Array.from(text.matchAll(shellRegex))
+    if (matches.length === 0) return text
+    const shell = yield* services.shell.preferred()
+    const outputs = yield* Effect.forEach(
+      matches,
+      (match) => {
+        const source = match[1] ?? ""
+        return services.processes
+          .run(
+            ChildProcess.make(shell, ShellSelect.args(shell, source), {
+              cwd: services.location.directory,
+              stdin: "ignore",
+            }),
+            { combineOutput: true },
+          )
+          .pipe(
+            Effect.map((result) => (result.output ?? Buffer.concat([result.stdout, result.stderr])).toString("utf8")),
+            Effect.mapError((error) =>
+              new Error(`Shell interpolation failed for ${JSON.stringify(source)}: ${error.message}`),
+            ),
+          )
+      },
+      { concurrency: 2 },
+    )
+    const iterator = outputs[Symbol.iterator]()
+    return text.replace(shellRegex, () => iterator.next().value ?? "")
+  })
+}
+
+function parseArguments(input: string) {
+  return (input.match(argsRegex) ?? []).map((arg) => arg.replace(quoteTrimRegex, ""))
+}
+
+const argsRegex = /(?:\[Image\s+\d+\]|"[^"]*"|'[^']*'|[^\s"']+)/gi
+const placeholderRegex = /\$(\d+)/g
+const quoteTrimRegex = /^["']|["']$/g
+const shellRegex = /!`([^`]+)`/g

packages/core/src/mcp/index.ts

@@ -2,7 +2,7 @@ export * as MCP from "./index.js"
 
 import { Mcp } from "@opencode-ai/schema/mcp"
 import { McpEvent } from "@opencode-ai/schema/mcp-event"
-import { Command } from "@opencode-ai/schema/command"
+import { ephemeral } from "@opencode-ai/schema/event"
 import { createHash } from "node:crypto"
 import { isDeepStrictEqual } from "node:util"
 import { Cause, Context, Effect, Exit, FiberSet, Latch, Layer, Schema, Scope, Stream, Types } from "effect"
@@ -19,6 +19,7 @@ import { State } from "../state.js"
 import type { MCPClient } from "./client.js"
 
 export const ServerName = Schema.String.pipe(Schema.brand("MCP.ServerName"))
+export const PromptsChanged = ephemeral({ type: "mcp.prompts.changed", schema: { server: Schema.String } })
 export type ServerName = typeof ServerName.Type
 
 // The status union is a public wire contract, so it lives in @opencode-ai/schema and is re-exported here.
@@ -453,7 +454,7 @@ export const layer = (options?: Options) =>
           Effect.map((defs) => {
             entry.prompts = defs.map((def) => toPrompt(name, def))
           }),
-          Effect.andThen(bus.publish(Command.Event.Updated, {})),
+          Effect.andThen(bus.publish(PromptsChanged, { server: name })),
         )
 
       // Runs a connection callback under the server lock, dropping it if the connection is no longer
@@ -572,7 +573,7 @@ export const layer = (options?: Options) =>
         yield* Scope.close(scope, Exit.void)
         yield* bus.publish(McpEvent.ToolsChanged, { server: name }).pipe(Effect.ignore)
         yield* bus.publish(McpEvent.ResourcesChanged, { server: name }).pipe(Effect.ignore)
-        yield* bus.publish(Command.Event.Updated, {}).pipe(Effect.ignore)
+        yield* bus.publish(PromptsChanged, { server: name }).pipe(Effect.ignore)
       })
 
       const disposeServer = Effect.fnUntraced(function* (name: ServerName, entry: ServerEntry) {

packages/core/src/plugin/command.ts

@@ -1,8 +1,10 @@
 export * as CommandPlugin from "./command.js"
 
 import { define } from "@opencode-ai/plugin/effect/plugin"
-import { Effect } from "effect"
+import { Effect, Stream } from "effect"
+import { Bus } from "../bus.js"
 import { Location } from "../location.js"
+import { MCP } from "../mcp/index.js"
 import PROMPT_INITIALIZE from "./command/initialize.txt"
 import PROMPT_REVIEW from "./command/review.txt"
 
@@ -10,15 +12,104 @@ export const Plugin = define({
   id: "opencode.command",
   effect: Effect.fn(function* (ctx) {
     const location = yield* Location.Service
+    const mcp = yield* MCP.Service
+    const bus = yield* Bus.Service
+    const loaded = { prompts: [] as MCP.Prompt[] }
+    yield* bus
+      .subscribe(MCP.PromptsChanged)
+      .pipe(
+        Stream.runForEach(() =>
+          mcp.prompts().pipe(
+            Effect.tap((prompts) => Effect.sync(() => (loaded.prompts = prompts))),
+            Effect.andThen(ctx.command.reload()),
+          ),
+        ),
+        Effect.forkScoped({ startImmediately: true }),
+      )
+    loaded.prompts = yield* mcp.prompts()
     yield* ctx.command.transform((draft) => {
-      draft.update("init", (command) => {
-        command.template = PROMPT_INITIALIZE.replace("${path}", location.project.directory)
-        command.description = "guided AGENTS.md setup"
+      draft.add({
+        name: "init",
+        description: "guided AGENTS.md setup",
+        execute: (input) =>
+          ctx.session
+            .prompt({
+              ...input.prompt,
+              sessionID: input.sessionID,
+              text: append(PROMPT_INITIALIZE.replace("${path}", location.project.directory), input.prompt.text),
+              delivery: input.delivery,
+            })
+            .pipe(Effect.asVoid),
       })
-      draft.update("review", (command) => {
-        command.template = PROMPT_REVIEW.replace("${path}", location.project.directory)
-        command.description = "review changes [commit|branch|pr], defaults to uncommitted"
+      draft.add({
+        name: "review",
+        description: "review changes [commit|branch|pr], defaults to uncommitted",
+        execute: (input) =>
+          ctx.session
+            .prompt({
+              ...input.prompt,
+              sessionID: input.sessionID,
+              text: append(PROMPT_REVIEW.replace("${path}", location.project.directory), input.prompt.text),
+              delivery: input.delivery,
+            })
+            .pipe(Effect.asVoid),
       })
+      for (const prompt of loaded.prompts) {
+        draft.add({
+          name: mcpCommandName(prompt.server, prompt.name),
+          description: prompt.description,
+          execute: (input) =>
+            Effect.gen(function* () {
+              const result = yield* mcp.prompt({
+                server: prompt.server,
+                name: prompt.name,
+                args: Object.fromEntries(
+                  (prompt.arguments ?? []).map((argument, index) => [
+                    argument.name,
+                    parseArguments(input.prompt.text)[index] ?? "",
+                  ]),
+                ),
+              })
+              if (!result) return yield* Effect.fail(new Error(`MCP prompt not found: ${prompt.server}:${prompt.name}`))
+              yield* ctx.session.prompt({
+                ...input.prompt,
+                sessionID: input.sessionID,
+                text: result.messages
+                  .map((message) => promptMessageText(message.content))
+                  .join("\n")
+                  .trim(),
+                delivery: input.delivery,
+              })
+            }).pipe(Effect.asVoid),
+        })
+      }
     })
   }),
 })
+
+function append(template: string, input: string) {
+  return [template, input.trim()].filter(Boolean).join("\n\n")
+}
+
+function parseArguments(input: string) {
+  return (input.match(argsRegex) ?? []).map((argument) => argument.replace(quoteTrimRegex, ""))
+}
+
+function promptMessageText(content: unknown) {
+  if (typeof content === "string") return content
+  if (!content || typeof content !== "object") return ""
+  if (!("type" in content) || content.type !== "text") return ""
+  if (!("text" in content) || typeof content.text !== "string") return ""
+  return content.text
+}
+
+function mcpCommandName(server: string, prompt: string) {
+  return `${sanitize(server)}:${sanitize(prompt)}`
+}
+
+function sanitize(value: string) {
+  return value.replace(/[^a-zA-Z0-9_-]/g, "_")
+}
+
+const argsRegex = /(?:\[Image\s+\d+\]|"[^"]*"|'[^']*'|[^\s"']+)/gi
+const quoteTrimRegex = /^["']|["']$/g

packages/core/src/plugin/host.ts

@@ -402,7 +402,10 @@ export const make = Effect.fn("PluginHost.make")(function* (plugin: Interface, p
       command: runtime.session.command,
       rename: runtime.session.rename,
       synthetic: runtime.session.synthetic,
-      interrupt: (input) => runtime.session.interrupt(input.sessionID),
+      interrupt: (input) =>
+        runtime.session
+          .interrupt(input.sessionID, { continue: input.continue })
+          .pipe(Effect.map((interrupted) => ({ interrupted }))),
       wait: (input) => runtime.session.wait(input.sessionID),
     },
   } satisfies Plugin.Context

packages/core/src/plugin/internal.ts

@@ -236,6 +236,7 @@ const pre = [
   MCPCodeModeExclusionPlugin.Plugin,
   WellKnownPlugin.Plugin,
   AgentPlugin.Plugin,
+  PlanPlugin.Plugin,
   CommandPlugin.Plugin,
   SkillPlugin.Plugin,
   ...SystemPromptPlugin.Plugins,
@@ -274,7 +275,6 @@ const post = [
   ConfigWebSearchPlugin.Plugin,
   VariantPlugin.Plugin,
   ConfigPolicyPlugin.Plugin,
-  PlanPlugin.Plugin,
 ] as const satisfies readonly InternalPlugin[]
 
 export const list = Effect.fn("PluginInternal.list")(function* () {

packages/core/src/plugin/provider/openai.ts

@@ -1,6 +1,7 @@
 import type { IntegrationOAuthMethodRegistration } from "@opencode-ai/plugin/effect/integration"
 import { define } from "@opencode-ai/plugin/effect/plugin"
 import { Deferred, Effect, Option, Schema, Semaphore, Stream } from "effect"
+import type { Server } from "node:http"
 import { App } from "../../app.js"
 import { Credential } from "../../credential.js"
 import { Bus } from "../../bus.js"
@@ -12,6 +13,9 @@ import type { PluginInternal } from "../internal.js"
 const clientID = "app_EMoamEEZ73f0CkXaXp7hrann"
 const issuer = "https://auth.openai.com"
 const callbackPort = 1455
+const callbackFallbackPort = 1457
+const callbackBindAttempts = 10
+const callbackBindRetryDelay = 200
 const pollingSafetyMargin = 3000
 const codexBaseURL = "https://chatgpt.com/backend-api/codex"
 const browserMethodID = Integration.MethodID.make("chatgpt-browser")
@@ -55,11 +59,10 @@ const browser = (app: App.Info) =>
         const pkce = yield* Effect.promise(generatePKCE)
         const state = base64UrlEncode(crypto.getRandomValues(new Uint8Array(32)).buffer)
         const code = yield* Deferred.make<string, Error>()
-        const redirect = `http://localhost:${callbackPort}/auth/callback`
         // Lazy so runtimes without a loopback listener (workerd) never evaluate node:http.
         const { createServer } = yield* Effect.promise(() => import("node:http"))
         const server = createServer((request, response) => {
-          const url = new URL(request.url ?? "/", `http://localhost:${callbackPort}`)
+          const url = new URL(request.url ?? "/", "http://localhost")
           if (url.pathname !== "/auth/callback") {
             response.writeHead(404).end("Not found")
             return
@@ -86,11 +89,9 @@ const browser = (app: App.Info) =>
             .writeHead(200, { "Content-Type": "text/html" })
             .end(OauthCallbackPage.success({ provider: "ChatGPT" }))
         })
-        yield* Effect.callback<void, Error>((resume) => {
-          server.once("error", (error) => resume(Effect.fail(error)))
-          server.listen(callbackPort, "localhost", () => resume(Effect.void))
-        })
+        const port = yield* listen(server)
         yield* Effect.addFinalizer(() => Effect.sync(() => server.close()))
+        const redirect = `http://localhost:${port}/auth/callback`
         return {
           mode: "auto" as const,
           url: authorizeURL(redirect, pkce, state),
@@ -104,6 +105,66 @@ const browser = (app: App.Info) =>
     refresh: (value) => refresh(browserMethodID, value, app),
   }) satisfies IntegrationOAuthMethodRegistration
 
+function listen(server: Server) {
+  return bind(server, callbackPort).pipe(
+    Effect.as(callbackPort),
+    Effect.catchIf(addressInUse, () =>
+      cancel(callbackPort).pipe(
+        Effect.ignore,
+        Effect.andThen(Effect.sleep(callbackBindRetryDelay)),
+        Effect.andThen(bindWithRetry(server, callbackPort, callbackBindAttempts - 1)),
+        Effect.as(callbackPort),
+        Effect.catchIf(addressInUse, () =>
+          bindWithRetry(server, callbackFallbackPort, callbackBindAttempts).pipe(
+            Effect.as(callbackFallbackPort),
+            Effect.catchIf(addressInUse, () =>
+              Effect.fail(
+                new Error(
+                  `OpenAI browser login needs local port ${callbackPort} or ${callbackFallbackPort}, but both are already in use. Stop the processes using those ports or choose ChatGPT Pro/Plus (headless), then try again.`,
+                ),
+              ),
+            ),
+          ),
+        ),
+      ),
+    ),
+  )
+}
+
+function bindWithRetry(server: Server, port: number, attempts: number): Effect.Effect<void, Error> {
+  return bind(server, port).pipe(
+    Effect.catchIf(
+      (error) => addressInUse(error) && attempts > 1,
+      () => Effect.sleep(callbackBindRetryDelay).pipe(Effect.andThen(bindWithRetry(server, port, attempts - 1))),
+    ),
+  )
+}
+
+function bind(server: Server, port: number) {
+  return Effect.callback<void, Error>((resume) => {
+    const onError = (error: Error) => resume(Effect.fail(error))
+    server.once("error", onError)
+    server.listen(port, "localhost", () => {
+      server.off("error", onError)
+      resume(Effect.void)
+    })
+  })
+}
+
+function cancel(port: number) {
+  return Effect.tryPromise({
+    try: (signal) =>
+      fetch(`http://localhost:${port}/cancel`, {
+        signal: AbortSignal.any([signal, AbortSignal.timeout(2000)]),
+      }),
+    catch: (cause) => cause,
+  })
+}
+
+function addressInUse(error: Error) {
+  return "code" in error && error.code === "EADDRINUSE"
+}
+
 const headless = (app: App.Info) =>
   ({
     integrationID: Integration.ID.make("openai"),

packages/core/src/plugin/skill/opencode.md

@@ -146,8 +146,10 @@ bug.
 
 For questions about creating, configuring, loading, publishing, or migrating
 plugins, fetch the full [plugins guide](https://opencode.ai/v2/docs/build/plugins)
-before answering. This includes questions about the Effect plugin API, hooks,
-transforms, tools, plugin context capabilities, and package entrypoints.
+before answering. Refer to this guide when the user wants to build a plugin. It
+covers hooks, transforms, tools, plugin context capabilities, and package
+entrypoints. Plugins can also extend the TUI; for those, fetch the
+[CLI plugin guide](https://opencode.ai/v2/docs/build/plugins/cli).
 
 ## [Service](https://opencode.ai/v2/docs/troubleshooting#check-the-background-service)
 

packages/core/src/session.ts

@@ -246,26 +246,14 @@ export interface Interface {
     prompt: string
   }) => Effect.Effect<string, NotFoundError | SessionGenerate.Error>
   readonly command: (input: {
-    id?: SessionMessage.ID
     sessionID: SessionSchema.ID
     command: string
-    arguments?: string
-    agent?: Agent.ID
-    model?: Model.Ref
+    text: string
     files?: PromptInput.Prompt["files"]
     agents?: PromptInput.Prompt["agents"]
     skills?: PromptInput.Prompt["skills"]
     delivery?: SessionInbox.Delivery
-    resume?: boolean
-  }) => Effect.Effect<
-    SessionInbox.User,
-    | NotFoundError
-    | PromptConflictError
-    | AttachmentError
-    | SkillNotFoundError
-    | Command.NotFoundError
-    | Command.EvaluationError
-  >
+  }) => Effect.Effect<void, NotFoundError | Command.NotFoundError | Command.ExecutionError>
   readonly shell: (input: {
     id?: Event.ID
     sessionID: SessionSchema.ID
@@ -284,7 +272,7 @@ export interface Interface {
   readonly active: Effect.Effect<ReadonlySet<SessionSchema.ID>>
   readonly background: (sessionID: SessionSchema.ID) => Effect.Effect<void, NotFoundError>
   readonly resume: (sessionID: SessionSchema.ID) => Effect.Effect<void, NotFoundError | SessionRunner.RunError>
-  readonly interrupt: (sessionID: SessionSchema.ID, options?: { readonly continue?: boolean }) => Effect.Effect<void>
+  readonly interrupt: (sessionID: SessionSchema.ID, options?: { readonly continue?: boolean }) => Effect.Effect<boolean>
   readonly synthetic: (input: {
     id?: SessionMessage.ID
     sessionID: SessionSchema.ID
@@ -655,35 +643,19 @@ const layer = Layer.effect(
           yield* plugins.flush
           return yield* Command.Service
         }).pipe(Effect.provide(locations.get(session.location)))
-        const command = yield* commands.get(input.command)
-        if (!command)
-          return yield* new Command.NotFoundError({
-            command: input.command,
-            message: `Command not found: ${input.command}`,
-          })
-        const evaluated = yield* commands.evaluate({ name: input.command, arguments: input.arguments })
-
-        // TODO(v2 commands): decide whether command-level subtask/background execution belongs in v2 commands.
-        const agent = command.agent ?? input.agent
-        const commandAgent = yield* Effect.gen(function* () {
-          if (!command.agent) return undefined
-          const agents = yield* Agent.Service.pipe(Effect.provide(locations.get(session.location)))
-          return yield* agents.get(Agent.ID.make(command.agent))
-        })
-        const model = command.model ?? commandAgent?.model ?? input.model
-        if (agent !== undefined && session.agent !== Agent.ID.make(agent))
-          yield* result.switchAgent({ sessionID: input.sessionID, agent: Agent.ID.make(agent) })
-        if (model !== undefined) yield* result.switchModel({ sessionID: input.sessionID, model })
-
-        return yield* result.prompt({
-          id: input.id,
-          sessionID: input.sessionID,
-          text: evaluated.text,
-          files: input.files,
-          agents: input.agents,
-          skills: input.skills,
-          delivery: input.delivery,
-          resume: input.resume,
+        const delivery = input.delivery ?? "steer"
+        yield* commands.execute({
+          name: input.command,
+          invocation: {
+            sessionID: input.sessionID,
+            prompt: {
+              text: input.text,
+              files: input.files,
+              agents: input.agents,
+              skills: input.skills,
+            },
+            delivery,
+          },
         })
       }),
       shell: Effect.fn("Session.shell")(function* (input) {

packages/core/src/session/execution.ts

@@ -24,9 +24,10 @@ export interface Interface {
   /**
    * Interrupt active work owned by this process. Idle interruption is a no-op. Resolves once
    * the interruption is accepted; cleanup settles asynchronously in the execution fiber.
-   * Compose with `awaitIdle` when settlement matters.
+   * Returns whether an active execution was interrupted. Compose with `awaitIdle` when
+   * settlement matters.
    */
-  readonly interrupt: (sessionID: SessionSchema.ID, options?: { readonly continue?: boolean }) => Effect.Effect<void>
+  readonly interrupt: (sessionID: SessionSchema.ID, options?: { readonly continue?: boolean }) => Effect.Effect<boolean>
   /** Resolves once this process owns no active execution for the Session. Returns immediately when idle and never starts work. */
   readonly awaitIdle: (sessionID: SessionSchema.ID) => Effect.Effect<void>
 }
@@ -140,8 +141,8 @@ export const layer = Layer.effect(
       active: coordinator.active,
       interrupt: (sessionID, options) =>
         Effect.gen(function* () {
-          yield* coordinator.interrupt(sessionID, "user")
-          if (!options?.continue) return
+          const interrupted = yield* coordinator.interrupt(sessionID, "user")
+          if (!options?.continue) return interrupted
           // Resume steering input and between-turn control work from the interrupted
           // intent. Queued next-turn prompts stay parked: a steer-scoped drain never
           // promotes them, and a control item behind a queued prompt waits its turn.
@@ -151,9 +152,10 @@ export const layer = Layer.effect(
           // rows inside uninterruptible publications, so a steer row is either still
           // promotable here or was fully delivered and needs no resumption.
           const next = yield* SessionInbox.nextPromotable(db, sessionID, "input")
-          if (next === undefined) return
+          if (next === undefined) return interrupted
           if (next.delivery === "steer" || next.type === "compaction" || next.type === "move")
             yield* coordinator.wake(sessionID, "steer")
+          return interrupted
         }),
       resume: coordinator.run,
       wake: coordinator.wake,
@@ -175,7 +177,7 @@ export const noopLayer = Layer.succeed(
     active: Effect.succeed(new Set()),
     resume: () => Effect.void,
     wake: () => Effect.void,
-    interrupt: () => Effect.void,
+    interrupt: () => Effect.succeed(false),
     awaitIdle: () => Effect.void,
   }),
 )

packages/core/src/session/run-coordinator.ts

@@ -14,9 +14,10 @@ export interface Coordinator<Key, E, Reason = never> {
   /**
    * Stops the active execution and clears its doorbell. No-op when idle. Resolves once the
    * interruption is accepted, not when cleanup settles: the execution fiber finishes its
-   * finalizers and settled hook on its own time. Compose with `awaitIdle` for settlement.
+   * finalizers and settled hook on its own time. Returns whether an active execution was
+   * interrupted. Compose with `awaitIdle` for settlement.
    */
-  readonly interrupt: (key: Key, reason?: Reason) => Effect.Effect<void>
+  readonly interrupt: (key: Key, reason?: Reason) => Effect.Effect<boolean>
   /** Resolves once no execution is active for the key. Returns immediately when already idle and never starts work. */
   readonly awaitIdle: (key: Key) => Effect.Effect<void>
 }
@@ -134,16 +135,16 @@ export const make = <Key, E, Reason = never>(options: {
         start(key, false, scope)
       })
 
-    const interrupt = (key: Key, reason?: Reason): Effect.Effect<void> =>
-      Effect.suspend(() => {
+    const interrupt = (key: Key, reason?: Reason): Effect.Effect<boolean> =>
+      Effect.sync(() => {
         const execution = executions.get(key)
-        if (execution === undefined || execution.stopping) return Effect.void
+        if (execution === undefined || execution.stopping) return false
         if (execution.owner === undefined) {
           // Settlement window: the owner exited but the settled hook has not finished. The
           // terminal outcome is already decided, so no reason attaches — but the interrupt
           // still claims the recorded wakes so settle does not start a dead-intent successor.
           execution.pendingWake = undefined
-          return Effect.void
+          return false
         }
         execution.stopping = true
         // Wakes recorded so far belong to the interrupted intent; the interrupt claims them.
@@ -153,7 +154,7 @@ export const make = <Key, E, Reason = never>(options: {
         // Fire and forget: nobody benefits from waiting out cleanup here, and callers like
         // the interrupt endpoint must acknowledge immediately even when finalizers are slow.
         fork(Fiber.interrupt(execution.owner))
-        return Effect.void
+        return true
       })
 
     // One execution's `done` already spans coalesced continuations; re-check after it

packages/core/src/tool/runtime.ts

@@ -1,7 +1,18 @@
 import type { ToolDefinition } from "@opencode-ai/ai"
 import { Tool } from "@opencode-ai/schema/tool"
 import type { StandardJSONSchemaV1, StandardSchemaV1 } from "@standard-schema/spec"
-import { Effect, JsonSchema, Schema } from "effect"
+import { Cache, Effect, JsonSchema, Schema, SchemaRepresentation } from "effect"
+
+const jsonSchemas = Effect.runSync(
+  Cache.make<JsonSchema.JsonSchema, Schema.Codec<unknown> | undefined>({
+    capacity: 100,
+    lookup: (schema) =>
+      Effect.try({
+        try: () => jsonSchema(schema),
+        catch: () => undefined,
+      }).pipe(Effect.orElseSucceed(() => undefined)),
+  }),
+)
 
 export const definition = (tool: Tool.Info<any, any>): ToolDefinition => ({
   name: effectiveName(tool),
@@ -50,7 +61,20 @@ const decodeInput = (schema: Tool.ValueSchema<any>, value: unknown) => {
       Effect.mapError((error) => new Tool.Error({ message: `Invalid tool input: ${error.message}` })),
     )
   if (isStandardSchema(schema)) return validateStandard(schema, value, "Invalid tool input")
-  return Effect.succeed(value)
+  return Cache.get(jsonSchemas, schema).pipe(
+    Effect.flatMap((schema) =>
+      schema === undefined ? Effect.succeed(value) : Schema.decodeUnknownEffect(schema)(value),
+    ),
+    Effect.mapError((error) => new Tool.Error({ message: `Invalid tool input: ${error.message}` })),
+  )
+}
+
+const jsonSchema = (schema: JsonSchema.JsonSchema) => {
+  const draft =
+    (typeof schema.$schema === "string" && schema.$schema.includes("draft-07")) || "definitions" in schema
+      ? JsonSchema.fromSchemaDraft07(schema)
+      : JsonSchema.fromSchemaDraft2020_12(schema)
+  return Schema.make<Schema.Codec<unknown>>(SchemaRepresentation.fromJsonSchemaDocument(draft).ast)
 }
 
 const encodeOutput = (schema: Tool.ValueSchema<any>, value: unknown) => {

packages/core/src/workspace.ts

@@ -25,9 +25,18 @@ export class Info extends Schema.Class<Info>("Workspace.Info")({
 
 export class NotFound extends Schema.TaggedError<NotFound>()("Workspace.NotFound", { workspaceID: ID }) {}
 
+export class CreateConflict extends Schema.TaggedError<CreateConflict>()("Workspace.CreateConflict", {
+  workspaceID: ID,
+  provider: Schema.String,
+  existingProvider: Schema.String,
+}) {}
+
 export interface Interface {
   /** Instantly commits a logical workspace ID. No provider work happens here. */
-  readonly create: (provider: string) => Effect.Effect<ID, WorkspaceDriver.ProviderNotFound>
+  readonly create: (input: {
+    readonly id?: ID
+    readonly provider: string
+  }) => Effect.Effect<ID, CreateConflict | WorkspaceDriver.ProviderNotFound>
   /** Starts or joins the shared attempt that makes the backing resource real, then returns it. */
   readonly provision: (
     workspaceID: ID,
@@ -35,9 +44,11 @@ export interface Interface {
   readonly connect: (
     workspaceID: ID,
   ) => Effect.Effect<EnvironmentDriver, NotFound | WorkspaceDriver.Error | WorkspaceDriver.ProviderNotFound>
-  readonly destroy: (
-    workspaceID: ID,
-  ) => Effect.Effect<void, NotFound | WorkspaceDriver.Error | WorkspaceDriver.ProviderNotFound>
+  /** Makes the workspace absent; reports whether this call destroyed an existing workspace. */
+  readonly destroy: (workspaceID: ID) => Effect.Effect<
+    Workspace.DestroyResult,
+    WorkspaceDriver.Error | WorkspaceDriver.ProviderNotFound
+  >
 }
 
 export interface Options {
@@ -79,13 +90,16 @@ const layer = (options: Options) =>
       const fork = yield* FiberSet.makeRuntime<never, void, never>()
       const idleThreshold = Duration.toMillis(options.idleThreshold ?? Duration.minutes(20))
 
-      const load = Effect.fn("Workspace.load")(function* (workspaceID: ID) {
-        const row = yield* db
+      const find = (workspaceID: ID) =>
+        db
           .select()
           .from(WorkspaceTable)
           .where(eq(WorkspaceTable.id, workspaceID))
           .get()
           .pipe(Effect.orDie)
+
+      const load = Effect.fn("Workspace.load")(function* (workspaceID: ID) {
+        const row = yield* find(workspaceID)
         if (!row) return yield* new NotFound({ workspaceID })
         return row
       })
@@ -207,15 +221,39 @@ const layer = (options: Options) =>
       }).pipe(Effect.repeat(Schedule.spaced(options.pollInterval ?? Duration.minutes(1))), Effect.forkScoped)
 
       return Service.of({
-        create: Effect.fn("Workspace.create")(function* (provider) {
-          yield* registry.get(provider)
-          const workspaceID = ID.create()
-          const now = yield* Clock.currentTimeMillis
-          yield* db
-            .insert(WorkspaceTable)
-            .values({ id: workspaceID, provider, binding: null, created_at: now, last_used_at: now })
-            .run()
+        create: Effect.fn("Workspace.create")(function* (input) {
+          const workspaceID = input.id ?? ID.create()
+          const existing = yield* db
+            .select({ provider: WorkspaceTable.provider })
+            .from(WorkspaceTable)
+            .where(eq(WorkspaceTable.id, workspaceID))
+            .get()
             .pipe(Effect.orDie)
+          if (existing) {
+            if (existing.provider === input.provider) return workspaceID
+            return yield* new CreateConflict({
+              workspaceID,
+              provider: input.provider,
+              existingProvider: existing.provider,
+            })
+          }
+          yield* registry.get(input.provider)
+          const now = yield* Clock.currentTimeMillis
+          const inserted = yield* db
+            .insert(WorkspaceTable)
+            .values({ id: workspaceID, provider: input.provider, binding: null, created_at: now, last_used_at: now })
+            .onConflictDoNothing()
+            .returning({ id: WorkspaceTable.id })
+            .get()
+            .pipe(Effect.orDie)
+          if (inserted) return workspaceID
+          const row = yield* load(workspaceID).pipe(Effect.orDie)
+          if (row.provider !== input.provider)
+            return yield* new CreateConflict({
+              workspaceID,
+              provider: input.provider,
+              existingProvider: row.provider,
+            })
           return workspaceID
         }),
         provision,
@@ -267,9 +305,10 @@ const layer = (options: Options) =>
             attempts.delete(workspaceID)
             Deferred.doneUnsafe(attempt, Exit.fail(new NotFound({ workspaceID })))
           }
-          yield* locks.withLock(workspaceID)(
+          return yield* locks.withLock(workspaceID)(
             Effect.gen(function* () {
-              const row = yield* load(workspaceID)
+              const row = yield* find(workspaceID)
+              if (!row) return { destroyed: false }
               const connection = connections.get(workspaceID)
               connections.delete(workspaceID)
               if (connection) yield* Scope.close(connection.scope, Exit.void)
@@ -284,6 +323,7 @@ const layer = (options: Options) =>
                 ),
               )
               yield* db.delete(WorkspaceTable).where(eq(WorkspaceTable.id, workspaceID)).run().pipe(Effect.orDie)
+              return { destroyed: true }
             }),
           )
         }),

packages/core/test/command.test.ts

@@ -1,77 +1,71 @@
 import { describe, expect } from "bun:test"
-import { Effect } from "effect"
 import { Command } from "@opencode-ai/core/command"
 import { AppNodeBuilder } from "@opencode-ai/core/effect/app-node-builder"
-import { Location } from "@opencode-ai/core/location"
-import { MCP } from "@opencode-ai/core/mcp/index"
-import { Model } from "@opencode-ai/core/model"
-import { Provider } from "@opencode-ai/core/provider"
-import { emptyMcpLayer, testLocationLayer } from "./fixture/mcp"
+import { Session } from "@opencode-ai/schema/session"
+import { Effect } from "effect"
 import { testEffect } from "./lib/effect"
 
-const it = testEffect(
-  AppNodeBuilder.build(Command.node, [
-    [MCP.node, emptyMcpLayer],
-    [Location.node, testLocationLayer],
-  ]),
-)
+const it = testEffect(AppNodeBuilder.build(Command.node))
 
 describe("Command", () => {
-  it.effect("applies command transforms and preserves later overrides", () =>
+  it.effect("registers and executes callback commands", () =>
     Effect.gen(function* () {
       const command = yield* Command.Service
-      yield* command.transform((editor) => {
-        editor.update("review", (command) => {
-          command.template = "First"
-          command.description = "Review code"
-        })
-        editor.update("review", (command) => {
-          command.template = "Second"
-          command.model = {
-            id: Model.ID.make("claude"),
-            providerID: Provider.ID.make("anthropic"),
-            variant: Model.VariantID.make("high"),
-          }
+      const calls: Command.Invocation[] = []
+      yield* command.transform((draft) => {
+        draft.add({
+          name: "goal",
+          description: "Manage the session goal",
+          execute: (input) => Effect.sync(() => calls.push(input)),
         })
       })
 
-      expect(yield* command.get("review")).toEqual(
-        Command.Info.make({
-          name: "review",
-          template: "Second",
-          description: "Review code",
-          model: {
-            id: Model.ID.make("claude"),
-            providerID: Provider.ID.make("anthropic"),
-            variant: Model.VariantID.make("high"),
-          },
-        }),
+      expect(yield* command.get("goal")).toEqual(
+        Command.Info.make({ name: "goal", description: "Manage the session goal" }),
       )
-      expect(yield* command.list()).toEqual([
-        Command.Info.make({
-          name: "review",
-          template: "Second",
-          description: "Review code",
-          model: {
-            id: Model.ID.make("claude"),
-            providerID: Provider.ID.make("anthropic"),
-            variant: Model.VariantID.make("high"),
-          },
-        }),
-      ])
+      const invocation = {
+        sessionID: Session.ID.make("ses_test"),
+        prompt: { text: "ship it", files: [{ uri: "file:///tmp/plan.md" }] },
+        delivery: "steer" as const,
+      }
+      yield* command.execute({ name: "goal", invocation })
+      expect(calls).toEqual([invocation])
     }),
   )
 
-  it.effect("evaluates command template shell blocks", () =>
+  it.effect("replaces commands with later definitions", () =>
     Effect.gen(function* () {
       const command = yield* Command.Service
-      yield* command.transform((editor) => {
-        editor.update("review", (command) => {
-          command.template = "Output: !`echo command-output`"
+      yield* command.transform((draft) => {
+        draft.add({ name: "goal", description: "First", execute: () => Effect.void })
+        draft.add({ name: "goal", description: "Second", execute: () => Effect.void })
+      })
+
+      expect(yield* command.list()).toEqual([Command.Info.make({ name: "goal", description: "Second" })])
+    }),
+  )
+
+  it.effect("returns callback error messages without stack traces", () =>
+    Effect.gen(function* () {
+      const command = yield* Command.Service
+      yield* command.transform((draft) => {
+        draft.add({
+          name: "fail",
+          execute: () => Effect.fail(new Error("command failed")),
         })
       })
 
-      expect((yield* command.evaluate({ name: "review" })).text.replace(/\r?\n$/, "")).toEqual("Output: command-output")
+      const error = yield* command
+        .execute({
+          name: "fail",
+          invocation: {
+            sessionID: Session.ID.make("ses_test"),
+            prompt: { text: "" },
+            delivery: "steer",
+          },
+        })
+        .pipe(Effect.flip)
+      expect(error).toMatchObject({ _tag: "Command.ExecutionError", message: "command failed" })
     }),
   )
 })

packages/core/test/config/command.test.ts

@@ -1,11 +1,13 @@
 import fs from "fs/promises"
 import path from "path"
 import { describe, expect } from "bun:test"
-import { Deferred, Effect, Fiber, Layer, Option, PubSub, Schema, Stream } from "effect"
+import { DateTime, Deferred, Effect, Fiber, Layer, Option, PubSub, Schema, Stream } from "effect"
 import { advance, drain } from "../lib/clock"
 import { Directory, Document, Event, Info } from "@opencode-ai/schema/config"
+import { Session } from "@opencode-ai/schema/session"
+import { SessionInbox } from "@opencode-ai/schema/session-inbox"
+import { SessionMessage } from "@opencode-ai/schema/session-message"
 import { Command } from "@opencode-ai/core/command"
-import { Agent } from "@opencode-ai/core/agent"
 import { Config } from "@opencode-ai/core/config"
 import { ConfigCommandPlugin } from "@opencode-ai/core/config/plugin/command"
 import { AppNodeBuilder } from "@opencode-ai/core/effect/app-node-builder"
@@ -15,11 +17,11 @@ import { Bus } from "@opencode-ai/core/bus"
 import { Credential } from "@opencode-ai/core/credential"
 import { WellKnown } from "@opencode-ai/core/wellknown"
 import { Global } from "@opencode-ai/util/global"
+import { AppProcess } from "@opencode-ai/util/process"
 import { Location } from "@opencode-ai/core/location"
 import { MCP } from "@opencode-ai/core/mcp/index"
-import { Model } from "@opencode-ai/core/model"
-import { Provider } from "@opencode-ai/core/provider"
 import { AbsolutePath } from "@opencode-ai/core/schema"
+import { ShellSelect } from "@opencode-ai/core/shell/select"
 import { Watcher } from "@opencode-ai/core/filesystem/watcher"
 import { emptyCredentialNode, emptyWellknownNode } from "../fixture/config-nodes"
 import { emptyConfigLayer, emptyMcpLayer, testLocationLayer } from "../fixture/mcp"
@@ -28,12 +30,25 @@ import { tmpdir } from "../fixture/tmpdir"
 import { testEffect } from "../lib/effect"
 import { host } from "../plugin/host"
 
+const shellLayer = Layer.succeed(
+  ShellSelect.Service,
+  ShellSelect.Service.of({
+    preferred: () => Effect.succeed("sh"),
+    transform: () => Effect.die("unused shell.transform"),
+    reload: () => Effect.die("unused shell.reload"),
+  }),
+)
+
 const it = testEffect(
-  AppNodeBuilder.build(LayerNode.group([Command.node, Bus.node, FSUtil.node]), [
-    [MCP.node, emptyMcpLayer],
-    [Config.node, emptyConfigLayer],
-    [Location.node, testLocationLayer],
-  ]),
+  AppNodeBuilder.build(
+    LayerNode.group([Command.node, Bus.node, FSUtil.node, AppProcess.node, Location.node, ShellSelect.node]),
+    [
+      [MCP.node, emptyMcpLayer],
+      [Config.node, emptyConfigLayer],
+      [Location.node, testLocationLayer],
+      [ShellSelect.node, shellLayer],
+    ],
+  ),
 )
 const decode = Schema.decodeUnknownSync(Info)
 
@@ -65,6 +80,7 @@ Review files`,
           const bus = yield* Bus.Service
           const update = yield* bus.publish(Event.Updated, {})
           const updates = yield* PubSub.unbounded<typeof update>()
+          const prompts: { text: string; files?: readonly { readonly uri: string }[]; delivery?: string }[] = []
           yield* ConfigCommandPlugin.Plugin.effect(
             host({
               command: {
@@ -73,6 +89,20 @@ Review files`,
                 reload: command.reload,
               },
               event: { subscribe: () => Stream.fromPubSub(updates) },
+              session: {
+                prompt: (input) =>
+                  Effect.sync(() => {
+                    prompts.push({ text: input.text, files: input.files, delivery: input.delivery })
+                    return SessionInbox.User.make({
+                      id: SessionMessage.ID.make("msg_test"),
+                      sessionID: input.sessionID,
+                      timeCreated: DateTime.makeUnsafe(0),
+                      type: "user",
+                      payload: { text: input.text },
+                      delivery: input.delivery ?? "steer",
+                    })
+                  }),
+              },
             }),
           ).pipe(
             Effect.provide(
@@ -89,28 +119,46 @@ Review files`,
           expect(yield* command.list()).toEqual([
             Command.Info.make({
               name: "review",
-              template: "Review files",
               description: "File review",
-              agent: Agent.ID.make("reviewer"),
-              model: {
-                providerID: Provider.ID.make("anthropic"),
-                id: Model.ID.make("claude"),
-                variant: Model.VariantID.make("high"),
-              },
-              subtask: true,
             }),
-            Command.Info.make({ name: "empty", template: "" }),
-            Command.Info.make({ name: "nested/docs", template: "Write docs" }),
+            Command.Info.make({ name: "empty" }),
+            Command.Info.make({ name: "nested/docs" }),
+          ])
+          yield* command.execute({
+            name: "nested/docs",
+            invocation: {
+              sessionID: Session.ID.make("ses_test"),
+              prompt: { text: "details", files: [{ uri: "file:///tmp/context.md" }] },
+              delivery: "queue",
+            },
+          })
+          expect(prompts).toEqual([
+            {
+              text: "Write docs\n\ndetails",
+              files: [{ uri: "file:///tmp/context.md" }],
+              delivery: "queue",
+            },
           ])
 
-          yield* Effect.promise(() => fs.writeFile(path.join(tmp.path, "commands", "review.md"), "Review again"))
+          yield* Effect.promise(() =>
+            fs.writeFile(path.join(tmp.path, "commands", "review.md"), markdown("Review again", "Review again")),
+          )
           yield* Effect.sleep("10 millis")
           yield* PubSub.publish(updates, update)
           for (let attempt = 0; attempt < 100; attempt++) {
-            if ((yield* command.get("review"))?.template === "Review again") break
+            if ((yield* command.get("review"))?.description === "Review again") break
             yield* Effect.sleep("10 millis")
           }
-          expect((yield* command.get("review"))?.template).toBe("Review again")
+          expect((yield* command.get("review"))?.description).toBe("Review again")
+          yield* command.execute({
+            name: "review",
+            invocation: {
+              sessionID: Session.ID.make("ses_test"),
+              prompt: { text: "latest" },
+              delivery: "steer",
+            },
+          })
+          expect(prompts.at(-1)?.text).toBe("Review again\n\nlatest")
         }),
       ),
     ),
@@ -193,11 +241,13 @@ Review files`,
           yield* advance(() => reloads >= 1)
           expect(reloads).toBe(1)
 
-          yield* Effect.promise(() => fs.writeFile(path.join(directory, "review.md"), "Review twice"))
+          yield* Effect.promise(() =>
+            fs.writeFile(path.join(directory, "review.md"), markdown("Review twice", "Review twice")),
+          )
           yield* configTest.emitChange({ type: "update", path: path.join(directory, "review.md") })
           yield* advance(() => reloads >= 2)
           expect(reloads).toBe(2)
-          expect((yield* command.get("review"))?.template).toBe("Review twice")
+          expect((yield* command.get("review"))?.description).toBe("Review twice")
         }).pipe(Effect.provide(Config.testLayer([directoryEntry(tmp.path)]))),
       ),
     ),
@@ -232,10 +282,12 @@ Review files`,
           expect(reloads).toBe(0)
 
           // The feed stays live after unrelated updates.
-          yield* Effect.promise(() => fs.writeFile(path.join(directory, "review.md"), "Review related"))
+          yield* Effect.promise(() =>
+            fs.writeFile(path.join(directory, "review.md"), markdown("Review related", "Review related")),
+          )
           yield* configTest.emitChange({ type: "create", path: path.join(directory, "review.md") })
           yield* advance(() => reloads >= 1)
-          expect((yield* command.get("review"))?.template).toBe("Review related")
+          expect((yield* command.get("review"))?.description).toBe("Review related")
         }).pipe(Effect.provide(Config.testLayer([directoryEntry(tmp.path)]))),
       ),
     ),
@@ -272,28 +324,47 @@ describeNative("ConfigCommandPlugin native watcher", () => {
         yield* watchReady(config, global)
 
         const created = yield* nextCommandUpdate(bus)
-        yield* fs.writeFileString(path.join(global, "commands", "review.md"), "Review native")
+        yield* fs.writeFileString(
+          path.join(global, "commands", "review.md"),
+          markdown("Review native", "Review native"),
+        )
         yield* Fiber.join(created).pipe(Effect.timeout("10 seconds"))
-        expect((yield* command.get("review"))?.template).toBe("Review native")
+        expect((yield* command.get("review"))?.description).toBe("Review native")
 
         const updated = yield* nextCommandUpdate(bus)
-        yield* fs.writeFileString(path.join(global, "commands", "review.md"), "Review native again")
+        yield* fs.writeFileString(
+          path.join(global, "commands", "review.md"),
+          markdown("Review native again", "Review native again"),
+        )
         yield* Fiber.join(updated).pipe(Effect.timeout("10 seconds"))
-        expect((yield* command.get("review"))?.template).toBe("Review native again")
+        expect((yield* command.get("review"))?.description).toBe("Review native again")
       }).pipe(
         Effect.provide(
-          AppNodeBuilder.build(LayerNode.group([Command.node, Config.node, Bus.node, FSUtil.node]), [
-            [
+          AppNodeBuilder.build(
+            LayerNode.group([
+              Command.node,
+              Config.node,
+              Bus.node,
+              FSUtil.node,
+              AppProcess.node,
+              Global.node,
               Location.node,
-              Layer.succeed(
-                Location.Service,
-                Location.Service.of(location({ directory: AbsolutePath.make(path.join(tmp, "project")) })),
-              ),
+              ShellSelect.node,
+            ]),
+            [
+              [
+                Location.node,
+                Layer.succeed(
+                  Location.Service,
+                  Location.Service.of(location({ directory: AbsolutePath.make(path.join(tmp, "project")) })),
+                ),
+              ],
+              [Global.node, Global.layerWith({ config: global, home: path.join(global, "home") })],
+              [ShellSelect.node, shellLayer],
+              [Credential.node, emptyCredentialNode],
+              [WellKnown.node, emptyWellknownNode],
             ],
-            [Global.node, Global.layerWith({ config: global, home: path.join(global, "home") })],
-            [Credential.node, emptyCredentialNode],
-            [WellKnown.node, emptyWellknownNode],
-          ]),
+          ),
         ),
       )
     }),
@@ -337,6 +408,10 @@ function directoryEntry(directory: string) {
   return new Directory({ type: "directory", path: AbsolutePath.make(directory) })
 }
 
+function markdown(description: string, template: string) {
+  return `---\ndescription: ${description}\n---\n${template}`
+}
+
 function sourceCases() {
   return [
     {
@@ -345,33 +420,37 @@ function sourceCases() {
       mutate: (directory: string) =>
         Effect.promise(async () => {
           const file = path.join(directory, "review.md")
-          await fs.writeFile(file, "Review created")
+          await fs.writeFile(file, markdown("Review created", "Review created"))
           return [{ type: "create" as const, path: file }]
         }),
       verify: (command: Command.Interface) =>
         Effect.gen(function* () {
-          expect((yield* command.get("review"))?.template).toBe("Review created")
+          expect((yield* command.get("review"))?.description).toBe("Review created")
         }),
     },
     {
       name: "updated",
       prepare: (directory: string) =>
-        Effect.promise(() => fs.writeFile(path.join(directory, "review.md"), "Review first")),
+        Effect.promise(() =>
+          fs.writeFile(path.join(directory, "review.md"), markdown("Review first", "Review first")),
+        ),
       mutate: (directory: string) =>
         Effect.promise(async () => {
           const file = path.join(directory, "review.md")
-          await fs.writeFile(file, "Review updated")
+          await fs.writeFile(file, markdown("Review updated", "Review updated"))
           return [{ type: "update" as const, path: file }]
         }),
       verify: (command: Command.Interface) =>
         Effect.gen(function* () {
-          expect((yield* command.get("review"))?.template).toBe("Review updated")
+          expect((yield* command.get("review"))?.description).toBe("Review updated")
         }),
     },
     {
       name: "renamed",
       prepare: (directory: string) =>
-        Effect.promise(() => fs.writeFile(path.join(directory, "review.md"), "Review renamed")),
+        Effect.promise(() =>
+          fs.writeFile(path.join(directory, "review.md"), markdown("Review renamed", "Review renamed")),
+        ),
       mutate: (directory: string) =>
         Effect.promise(async () => {
           const previous = path.join(directory, "review.md")
@@ -385,7 +464,7 @@ function sourceCases() {
       verify: (command: Command.Interface) =>
         Effect.gen(function* () {
           expect(yield* command.get("review")).toBeUndefined()
-          expect((yield* command.get("release"))?.template).toBe("Review renamed")
+          expect((yield* command.get("release"))?.description).toBe("Review renamed")
         }),
     },
     {

packages/core/test/config/plugin.test.ts

@@ -52,6 +52,17 @@ describe("PluginSupervisor config", () => {
     ),
   )
 
+  it.live("allows the built-in Plan agent to be disabled", () =>
+    withLocation(
+      { agents: { plan: { disabled: true } } },
+      Effect.gen(function* () {
+        yield* ready()
+        const agents = yield* Agent.Service
+        expect(yield* agents.get(Agent.ID.make("plan"))).toBeUndefined()
+      }),
+    ),
+  )
+
   it.live("loads configured Promise plugins with options", () =>
     withLocation(
       {

packages/core/test/config/reload.test.ts

@@ -14,16 +14,22 @@ import { Bus } from "@opencode-ai/core/bus"
 import { Integration } from "@opencode-ai/core/integration"
 import { Plugin } from "@opencode-ai/core/plugin"
 import { PluginHost } from "@opencode-ai/core/plugin/host"
+import { AppNodeBuilder } from "@opencode-ai/core/effect/app-node-builder"
 import { Provider } from "@opencode-ai/core/provider"
 import { Reference } from "@opencode-ai/core/reference"
 import { Skill } from "@opencode-ai/core/skill"
+import { ShellSelect } from "@opencode-ai/core/shell/select"
 import { Global } from "@opencode-ai/util/global"
-import { Effect, Schema } from "effect"
+import { AppProcess } from "@opencode-ai/util/process"
+import { Effect, Layer, Schema } from "effect"
+import { LayerNode } from "@opencode-ai/util/effect/layer-node"
 import { AbsolutePath } from "@opencode-ai/core/schema"
 import { testEffect } from "../lib/effect"
 import { PluginTestLayer } from "../plugin/fixture"
 
-const it = testEffect(PluginTestLayer)
+const it = testEffect(
+  Layer.merge(PluginTestLayer, AppNodeBuilder.build(LayerNode.group([AppProcess.node, ShellSelect.node]))),
+)
 const decode = Schema.decodeUnknownSync(Info)
 const document = path.join(import.meta.dir, "opencode.json")
 

packages/core/test/plugin/command.test.ts

@@ -1,10 +1,18 @@
 import { describe, expect } from "bun:test"
 import { Effect, Layer } from "effect"
 import { Command } from "@opencode-ai/core/command"
+import { Bus } from "@opencode-ai/core/bus"
 import { AppNodeBuilder } from "@opencode-ai/core/effect/app-node-builder"
 import { Location } from "@opencode-ai/core/location"
+import { MCP } from "@opencode-ai/core/mcp/index"
 import { CommandPlugin } from "@opencode-ai/core/plugin/command"
 import { AbsolutePath } from "@opencode-ai/core/schema"
+import { Session } from "@opencode-ai/schema/session"
+import { SessionInbox } from "@opencode-ai/schema/session-inbox"
+import { SessionMessage } from "@opencode-ai/schema/session-message"
+import { LayerNode } from "@opencode-ai/util/effect/layer-node"
+import { DateTime } from "effect"
+import { emptyMcpLayer } from "../fixture/mcp"
 import { location } from "../fixture/location"
 import { testEffect } from "../lib/effect"
 import { host } from "./host"
@@ -15,12 +23,18 @@ const locationLayer = Layer.succeed(
   Location.Service,
   Location.Service.of(location({ directory }, { projectDirectory: project })),
 )
-const it = testEffect(AppNodeBuilder.build(Command.node, [[Location.node, locationLayer]]))
+const it = testEffect(
+  AppNodeBuilder.build(LayerNode.group([Command.node, MCP.node, Bus.node]), [
+    [MCP.node, emptyMcpLayer],
+    [Location.node, locationLayer],
+  ]),
+)
 
 describe("CommandPlugin.Plugin", () => {
   it.effect("registers built-in init and review commands", () =>
     Effect.gen(function* () {
       const command = yield* Command.Service
+      const prompts: { text: string; files?: readonly { readonly uri: string }[] }[] = []
       yield* CommandPlugin.Plugin.effect(
         host({
           command: {
@@ -28,6 +42,20 @@ describe("CommandPlugin.Plugin", () => {
             transform: command.transform,
             reload: command.reload,
           },
+          session: {
+            prompt: (input) =>
+              Effect.sync(() => {
+                prompts.push({ text: input.text, files: input.files })
+                return SessionInbox.User.make({
+                  id: SessionMessage.ID.make("msg_test"),
+                  sessionID: input.sessionID,
+                  timeCreated: DateTime.makeUnsafe(0),
+                  type: "user",
+                  payload: { text: input.text },
+                  delivery: input.delivery ?? "steer",
+                })
+              }),
+          },
         }),
       ).pipe(
         Effect.provideService(
@@ -40,11 +68,24 @@ describe("CommandPlugin.Plugin", () => {
         name: "init",
         description: "guided AGENTS.md setup",
       })
-      expect((yield* command.get("init"))?.template).toContain("`/repo`")
       expect(yield* command.get("review")).toMatchObject({
         name: "review",
         description: "review changes [commit|branch|pr], defaults to uncommitted",
       })
+      yield* command.execute({
+        name: "init",
+        invocation: {
+          sessionID: Session.ID.make("ses_test"),
+          prompt: { text: "extra context", files: [{ uri: "file:///tmp/context.md" }] },
+          delivery: "queue",
+        },
+      })
+      expect(prompts).toEqual([
+        {
+          text: expect.stringContaining("extra context"),
+          files: [{ uri: "file:///tmp/context.md" }],
+        },
+      ])
     }),
   )
 })

packages/core/test/plugin/promise.test.ts

@@ -121,7 +121,7 @@ describe("fromPromise", () => {
     }),
   )
 
-  it.effect("preserves no-content and rejected Promise behavior", () =>
+  it.effect("preserves interrupt results and rejected Promise behavior", () =>
     Effect.gen(function* () {
       const seen: unknown[] = []
       const host = testHost({
@@ -131,7 +131,7 @@ describe("fromPromise", () => {
               return Effect.fail(new Error("interrupt failed"))
             }
             expect(input.continue).toBe(true)
-            return Effect.void
+            return Effect.succeed({ interrupted: false })
           },
           switchAgent: (input) => Effect.sync(() => seen.push(input)),
           switchModel: (input) => Effect.sync(() => seen.push(input)),
@@ -144,7 +144,9 @@ describe("fromPromise", () => {
         define({
           id: "promise-session-interrupt",
           setup: async (ctx) => {
-            expect(await ctx.session.interrupt({ sessionID: "ses_success", continue: true })).toBeUndefined()
+            expect(await ctx.session.interrupt({ sessionID: "ses_success", continue: true })).toEqual({
+              interrupted: false,
+            })
             await expect(ctx.session.interrupt({ sessionID: "ses_failure" })).rejects.toThrow("interrupt failed")
             expect(await ctx.session.switchAgent({ sessionID: "ses_success", agent: "build" })).toBeUndefined()
             expect(

packages/core/test/session-execution.test.ts

@@ -128,12 +128,25 @@ describe("SessionExecution lifecycle", () => {
       yield* Deferred.await(draining)
       expect((yield* claims(database))[sessionID]).toBe(true)
 
-      yield* execution.interrupt(sessionID)
+      expect(yield* execution.interrupt(sessionID)).toBeTrue()
       yield* execution.awaitIdle(sessionID)
       expect((yield* claims(database))[sessionID]).toBe(false)
     }),
   )
 
+  it.effect("reports an idle interrupt as a no-op", () =>
+    Effect.gen(function* () {
+      const sessionID = Session.ID.make("ses_idle_cancel")
+      const scope = yield* Scope.make()
+      yield* Effect.addFinalizer(() => Scope.close(scope, Exit.void))
+      const context = yield* buildExecution(scope, () => Effect.never)
+      const execution = Context.get(context, SessionExecution.Service)
+
+      expect(yield* execution.interrupt(sessionID)).toBeFalse()
+      expect(yield* execution.active).not.toContain(sessionID)
+    }),
+  )
+
   it.effect("starts every claimed execution without waiting for earlier drains to finish", () =>
     Effect.gen(function* () {
       const database = yield* Database.Service

packages/core/test/session-prompt.test.ts

@@ -48,6 +48,7 @@ const execution = Layer.succeed(
       Effect.sync(() => {
         interruptCalls.push(sessionID)
         interruptContinuations.push(options?.continue)
+        return activeSessions.delete(sessionID)
       }),
     wake: (sessionID) =>
       Effect.sync(() => {
@@ -193,7 +194,7 @@ describe("Session.prompt", () => {
       interruptCalls.length = 0
       wakeCalls.length = 0
 
-      yield* session.interrupt(sessionID)
+      expect(yield* session.interrupt(sessionID)).toBeFalse()
       expect(interruptCalls).toEqual([sessionID])
       expect(wakeCalls).toEqual([])
       expect(yield* session.messages({ sessionID })).toEqual([])

packages/core/test/session-run-coordinator.test.ts

@@ -236,7 +236,7 @@ describe("SessionRunCoordinator", () => {
           drain: () => Effect.void,
           settled: (_key, _exit, reason) => Effect.sync(() => void reasons.push(reason)),
         })
-        yield* coordinator.interrupt("session", "user")
+        expect(yield* coordinator.interrupt("session", "user")).toBeFalse()
         yield* coordinator.run("session")
         expect(reasons).toEqual([undefined])
       }),
@@ -260,7 +260,7 @@ describe("SessionRunCoordinator", () => {
 
         const run = yield* coordinator.run("session").pipe(Effect.forkChild)
         yield* Deferred.await(settling)
-        yield* coordinator.interrupt("session", "user")
+        expect(yield* coordinator.interrupt("session", "user")).toBeFalse()
         yield* Deferred.succeed(release, undefined)
         yield* Fiber.join(run)
         yield* coordinator.run("session")
@@ -315,7 +315,7 @@ describe("SessionRunCoordinator", () => {
         const idle = yield* coordinator.awaitIdle("session").pipe(Effect.forkChild)
         yield* Effect.yieldNow
         yield* coordinator.wake("session")
-        yield* coordinator.interrupt("session", "user")
+        expect(yield* coordinator.interrupt("session", "user")).toBeTrue()
         yield* Deferred.await(interrupted)
 
         const exits = yield* Fiber.awaitAll([first, second, idle])

packages/core/test/tool-schema.test.ts

@@ -152,19 +152,21 @@ test("portable schema failures become tool failures", async () => {
     },
   }
 
-  const error = await Effect.runPromiseExit(
-    execute(
-      {
-        name: "invalid",
-        description: "Invalid",
-        input,
-        execute: () => Effect.succeed({ content: "unused" }),
-      },
-      1,
-      {} as Tool.Context,
+  const error = await Effect.runPromise(
+    Effect.flip(
+      execute(
+        {
+          name: "invalid",
+          description: "Invalid",
+          input,
+          execute: () => Effect.succeed({ content: "unused" }),
+        },
+        1,
+        {} as Tool.Context,
+      ),
     ),
   )
-  expect(error.toString()).toContain("Invalid tool input: expected a string")
+  expect(error).toEqual(new Tool.Error({ message: "Invalid tool input: expected a string" }))
 })
 
 test("canonical results carry metadata with typed output", async () => {
@@ -185,8 +187,21 @@ test("canonical results carry metadata with typed output", async () => {
   })
 })
 
-test("raw JSON schemas are render-only and omitted output means model-only", async () => {
-  const input = { type: "object", properties: { value: { type: "string" } } }
+test("raw JSON schemas validate and decode tool input", async () => {
+  const input = {
+    type: "object",
+    properties: {
+      value: { type: "string" },
+      nested: {
+        type: "object",
+        properties: { count: { type: "integer", minimum: 1 } },
+        required: ["count"],
+        additionalProperties: false,
+      },
+    },
+    required: ["value"],
+    additionalProperties: false,
+  }
   const tool: Info = {
     name: "raw",
     description: "Raw tool",
@@ -197,11 +212,61 @@ test("raw JSON schemas are render-only and omitted output means model-only", asy
   expect(definition(tool)).toEqual({
     name: "raw",
     description: "Raw tool",
-    inputSchema: { type: "object", properties: { value: { type: "string" } } },
+    inputSchema: input,
   })
-  expect(await Effect.runPromise(execute(tool, { value: 1 }, {} as Tool.Context))).toEqual({
+  expect(await Effect.runPromise(execute(tool, { value: "ok", extra: true }, {} as Tool.Context))).toEqual({
     output: undefined,
-    content: [{ type: "text", text: '{"value":1}' }],
+    content: [{ type: "text", text: '{"value":"ok"}' }],
+  })
+  expect(await Effect.runPromise(Effect.flip(execute(tool, { value: 1 }, {} as Tool.Context)))).toEqual(
+    new Tool.Error({ message: 'Invalid tool input: Expected string\n  at ["value"]' }),
+  )
+  expect(await Effect.runPromise(Effect.flip(execute(tool, {}, {} as Tool.Context)))).toEqual(
+    new Tool.Error({ message: 'Invalid tool input: Missing key\n  at ["value"]' }),
+  )
+  expect(
+    await Effect.runPromise(Effect.flip(execute(tool, { value: "ok", nested: { count: 0 } }, {} as Tool.Context))),
+  ).toEqual(
+    new Tool.Error({
+      message: 'Invalid tool input: Expected a value greater than or equal to 1\n  at ["nested"]["count"]',
+    }),
+  )
+})
+
+test("raw JSON schemas resolve draft-07 definitions", async () => {
+  const tool: Info = {
+    name: "draft-07",
+    description: "Draft-07 tool",
+    input: {
+      type: "object",
+      properties: { value: { $ref: "#/definitions/value" } },
+      required: ["value"],
+      definitions: { value: { type: "string" } },
+    },
+    execute: (input) => Effect.succeed({ content: JSON.stringify(input) }),
+  }
+
+  expect(await Effect.runPromise(execute(tool, { value: "ok" }, {} as Tool.Context))).toMatchObject({
+    content: [{ type: "text", text: '{"value":"ok"}' }],
+  })
+  expect(await Effect.runPromise(Effect.flip(execute(tool, { value: 1 }, {} as Tool.Context)))).toEqual(
+    new Tool.Error({ message: 'Invalid tool input: Expected value\n  at ["value"]' }),
+  )
+})
+
+test("raw JSON schemas pass input through when they cannot be imported", async () => {
+  const tool: Info = {
+    name: "invalid-schema",
+    description: "Invalid schema tool",
+    input: {
+      type: "object",
+      properties: { value: { $ref: "#/$defs/missing" } },
+    },
+    execute: (input) => Effect.succeed({ content: JSON.stringify(input) }),
+  }
+
+  expect(await Effect.runPromise(execute(tool, { value: 1, extra: true }, {} as Tool.Context))).toMatchObject({
+    content: [{ type: "text", text: '{"value":1,"extra":true}' }],
   })
 })
 

packages/core/test/tool-shell.test.ts

@@ -115,7 +115,7 @@ const executionNode = makeGlobalNode({
         active: Effect.succeed(new Set()),
         resume: complete,
         wake: () => Effect.void,
-        interrupt: () => Effect.void,
+        interrupt: () => Effect.succeed(false),
         awaitIdle: (id) => complete(id).pipe(Effect.exit, Effect.asVoid),
       })
     }),

packages/core/test/tool-subagent.test.ts

@@ -88,7 +88,7 @@ const executionNode = makeGlobalNode({
         active: Effect.succeed(new Set()),
         resume: complete,
         wake: () => Effect.void,
-        interrupt: () => Effect.void,
+        interrupt: () => Effect.succeed(false),
         awaitIdle: (sessionID) => complete(sessionID).pipe(Effect.exit, Effect.asVoid),
       })
     }),

packages/core/test/workspace.test.ts

@@ -41,7 +41,7 @@ const driver = WorkspaceDriver.make({
 const it = testEffect(
   AppNodeBuilder.build(
     LayerNode.group([Database.node, Workspace.configured({ idleThreshold: "5 minutes", pollInterval: "1 minute" })]),
-    [[WorkspaceDriver.node, WorkspaceDriver.registryNode({ fake: driver })]],
+    [[WorkspaceDriver.node, WorkspaceDriver.registryNode({ fake: driver, other: driver })]],
   ),
 )
 
@@ -77,7 +77,7 @@ it.effect("rejects unregistered workspace providers", () =>
 it.effect("creates and persists an ID without provisioning", () =>
   Effect.gen(function* () {
     const workspace = yield* Workspace.Service
-    const workspaceID = yield* workspace.create("fake")
+    const workspaceID = yield* workspace.create({ provider: "fake" })
 
     expect(workspaceID.startsWith("wrk_")).toBe(true)
     expect(calls).toEqual([])
@@ -89,12 +89,76 @@ it.effect("creates and persists an ID without provisioning", () =>
   }),
 )
 
+it.effect("creates a workspace with a caller-supplied ID", () =>
+  Effect.gen(function* () {
+    const workspace = yield* Workspace.Service
+    const id = Workspace.ID.create()
+
+    expect(yield* workspace.create({ id, provider: "fake" })).toBe(id)
+    expect(
+      yield* Database.Service.use(({ db }) =>
+        db.select().from(WorkspaceTable).where(eq(WorkspaceTable.id, id)).get(),
+      ).pipe(Effect.orDie),
+    ).toMatchObject({ id, provider: "fake", binding: null })
+  }),
+)
+
+it.effect("reuses a caller-supplied ID with the same provider", () =>
+  Effect.gen(function* () {
+    const workspace = yield* Workspace.Service
+    const id = Workspace.ID.create()
+
+    expect(yield* workspace.create({ id, provider: "fake" })).toBe(id)
+    expect(yield* workspace.create({ id, provider: "fake" })).toBe(id)
+    expect(
+      yield* Database.Service.use(({ db }) =>
+        db.select().from(WorkspaceTable).where(eq(WorkspaceTable.id, id)).all(),
+      ).pipe(Effect.orDie),
+    ).toHaveLength(1)
+    expect(calls).toEqual([])
+  }),
+)
+
+it.effect("rejects a caller-supplied ID already assigned to another provider", () =>
+  Effect.gen(function* () {
+    const workspace = yield* Workspace.Service
+    const id = Workspace.ID.create()
+    yield* workspace.create({ id, provider: "fake" })
+
+    expect(yield* workspace.create({ id, provider: "other" }).pipe(Effect.flip)).toEqual(
+      new Workspace.CreateConflict({ workspaceID: id, provider: "other", existingProvider: "fake" }),
+    )
+  }),
+)
+
+it.effect("resolves an existing caller-supplied ID before provider lookup", () =>
+  Effect.gen(function* () {
+    const workspace = yield* Workspace.Service
+    const id = Workspace.ID.create()
+    yield* Database.Service.use(({ db }) =>
+      db
+        .insert(WorkspaceTable)
+        .values({ id, provider: "missing", binding: null, created_at: 0, last_used_at: 0 })
+        .run(),
+    ).pipe(Effect.orDie)
+
+    expect(yield* workspace.create({ id, provider: "missing" })).toBe(id)
+    expect(yield* workspace.create({ id, provider: "another-missing" }).pipe(Effect.flip)).toEqual(
+      new Workspace.CreateConflict({
+        workspaceID: id,
+        provider: "another-missing",
+        existingProvider: "missing",
+      }),
+    )
+  }),
+)
+
 it.effect("destroys an unprovisioned workspace through the driver with a null binding", () =>
   Effect.gen(function* () {
     const workspace = yield* Workspace.Service
-    const workspaceID = yield* workspace.create("fake")
+    const workspaceID = yield* workspace.create({ provider: "fake" })
 
-    yield* workspace.destroy(workspaceID)
+    expect(yield* workspace.destroy(workspaceID)).toEqual({ destroyed: true })
     expect(calls).toEqual([{ operation: "destroy", binding: null }])
     expect(
       yield* Database.Service.use(({ db }) =>
@@ -104,10 +168,31 @@ it.effect("destroys an unprovisioned workspace through the driver with a null bi
   }),
 )
 
+it.effect("succeeds without calling the driver when the workspace does not exist", () =>
+  Effect.gen(function* () {
+    const workspace = yield* Workspace.Service
+    const workspaceID = Workspace.ID.create()
+
+    expect(yield* workspace.destroy(workspaceID)).toEqual({ destroyed: false })
+    expect(calls).toEqual([])
+  }),
+)
+
+it.effect("reports whether destroy removed an existing workspace", () =>
+  Effect.gen(function* () {
+    const workspace = yield* Workspace.Service
+    const workspaceID = yield* workspace.create({ provider: "fake" })
+
+    expect(yield* workspace.destroy(workspaceID)).toEqual({ destroyed: true })
+    expect(yield* workspace.destroy(workspaceID)).toEqual({ destroyed: false })
+    expect(calls).toEqual([{ operation: "destroy", binding: null }])
+  }),
+)
+
 it.effect("starts eager provisioning in the background and lets callers join it", () =>
   Effect.gen(function* () {
     const workspace = yield* Workspace.Service
-    const workspaceID = yield* workspace.create("fake")
+    const workspaceID = yield* workspace.create({ provider: "fake" })
     const gate = yield* gateCreate()
 
     const eager = yield* workspace.provision(workspaceID).pipe(Effect.forkScoped({ startImmediately: true }))
@@ -126,7 +211,7 @@ it.effect("starts eager provisioning in the background and lets callers join it"
 it.effect("starts lazy provisioning on the first spawn", () =>
   Effect.gen(function* () {
     const workspace = yield* Workspace.Service
-    const workspaceID = yield* workspace.create("fake")
+    const workspaceID = yield* workspace.create({ provider: "fake" })
     const environment = yield* workspace.connect(workspaceID)
     const gate = yield* gateCreate()
 
@@ -145,7 +230,7 @@ it.effect("starts lazy provisioning on the first spawn", () =>
 it.effect("shares provisioning between concurrent first spawns", () =>
   Effect.gen(function* () {
     const workspace = yield* Workspace.Service
-    const workspaceID = yield* workspace.create("fake")
+    const workspaceID = yield* workspace.create({ provider: "fake" })
     const environment = yield* workspace.connect(workspaceID)
     const gate = yield* gateCreate()
 
@@ -169,7 +254,7 @@ it.effect("shares provisioning between concurrent first spawns", () =>
 it.effect("keeps shared provisioning alive when a waiter is interrupted", () =>
   Effect.gen(function* () {
     const workspace = yield* Workspace.Service
-    const workspaceID = yield* workspace.create("fake")
+    const workspaceID = yield* workspace.create({ provider: "fake" })
     const gate = yield* gateCreate()
 
     const owner = yield* workspace.provision(workspaceID).pipe(Effect.forkScoped({ startImmediately: true }))
@@ -187,7 +272,7 @@ it.effect("keeps shared provisioning alive when a waiter is interrupted", () =>
 it.effect("interrupts in-flight provisioning on destroy and fails waiters with NotFound", () =>
   Effect.gen(function* () {
     const workspace = yield* Workspace.Service
-    const workspaceID = yield* workspace.create("fake")
+    const workspaceID = yield* workspace.create({ provider: "fake" })
     const gate = yield* gateCreate()
 
     const waiter = yield* workspace.provision(workspaceID).pipe(Effect.forkScoped({ startImmediately: true }))
@@ -208,7 +293,7 @@ it.effect("interrupts in-flight provisioning on destroy and fails waiters with N
 it.effect("shares a failed attempt and retries the same workspace ID", () =>
   Effect.gen(function* () {
     const workspace = yield* Workspace.Service
-    const workspaceID = yield* workspace.create("fake")
+    const workspaceID = yield* workspace.create({ provider: "fake" })
     const started = yield* Deferred.make<void>()
     const release = yield* Deferred.make<void>()
     let fail = true
@@ -242,7 +327,7 @@ it.effect("shares a failed attempt and retries the same workspace ID", () =>
 it.effect("persists the workspace lifecycle and reconnects after idle suspension", () =>
   Effect.gen(function* () {
     const workspace = yield* Workspace.Service
-    const workspaceID = yield* workspace.create("fake")
+    const workspaceID = yield* workspace.create({ provider: "fake" })
     const created = yield* workspace.provision(workspaceID)
 
     expect(created.id).toBe(workspaceID)
@@ -277,7 +362,7 @@ it.effect("persists the workspace lifecycle and reconnects after idle suspension
 it.effect("surfaces wake failures through the spawn error channel", () =>
   Effect.gen(function* () {
     const workspace = yield* Workspace.Service
-    const created = yield* workspace.provision(yield* workspace.create("fake"))
+    const created = yield* workspace.provision(yield* workspace.create({ provider: "fake" }))
     const environment = yield* workspace.connect(created.id)
     yield* Effect.scoped(environment.spawner.spawn(ChildProcess.make("connect"))).pipe(Effect.exit)
 

packages/function/package.json

@@ -5,6 +5,9 @@
   "private": true,
   "type": "module",
   "license": "MIT",
+  "scripts": {
+    "test": "bun test"
+  },
   "devDependencies": {
     "@cloudflare/workers-types": "catalog:",
     "@tsconfig/node22": "22.0.2",

packages/function/src/api.ts

@@ -5,6 +5,7 @@ import { jwtVerify, createRemoteJWKSet } from "jose"
 import { createAppAuth } from "@octokit/auth-app"
 import { Octokit } from "@octokit/rest"
 import { Resource } from "sst"
+import { parseRepositoryClaim } from "./github"
 
 type Env = {
   SYNC_SERVER: DurableObjectNamespace<SyncServer>
@@ -269,42 +270,41 @@ export default new Hono<{ Bindings: Env }>()
 
     // verify token
     const JWKS = createRemoteJWKSet(new URL(JWKS_URL))
-    let owner, repo
+    let repository: ReturnType<typeof parseRepositoryClaim>
     try {
       const { payload } = await jwtVerify(token, JWKS, {
         issuer: GITHUB_ISSUER,
         audience: EXPECTED_AUDIENCE,
       })
-      const sub = payload.sub // e.g. 'repo:my-org/my-repo:ref:refs/heads/main'
-      const parts = sub.split(":")[1].split("/")
-      owner = parts[0]
-      repo = parts[1]
+      repository = parseRepositoryClaim(payload)
     } catch (err) {
       console.error("Token verification failed:", err)
       return c.json({ error: "Invalid or expired token" }, { status: 403 })
     }
 
-    // Create app JWT token
-    const auth = createAppAuth({
-      appId: Resource.GITHUB_APP_ID.value,
-      privateKey: Resource.GITHUB_APP_PRIVATE_KEY.value,
-    })
-    const appAuth = await auth({ type: "app" })
-
-    // Lookup installation
-    const octokit = new Octokit({ auth: appAuth.token })
-    const { data: installation } = await octokit.apps.getRepoInstallation({
-      owner,
-      repo,
-    })
-
-    // Get installation token
-    const installationAuth = await auth({
-      type: "installation",
-      installationId: installation.id,
-    })
-
-    return c.json({ token: installationAuth.token })
+    try {
+      const auth = createAppAuth({
+        appId: Resource.GITHUB_APP_ID.value,
+        privateKey: Resource.GITHUB_APP_PRIVATE_KEY.value,
+      })
+      const appAuth = await auth({ type: "app" })
+      const octokit = new Octokit({ auth: appAuth.token })
+      const { data: installation } = await octokit.apps.getRepoInstallation({
+        owner: repository.owner,
+        repo: repository.repo,
+      })
+      const installationAuth = await auth({
+        type: "installation",
+        installationId: installation.id,
+      })
+      return c.json({ token: installationAuth.token })
+    } catch (error) {
+      console.error("GitHub App token exchange failed:", error)
+      return c.json(
+        { error: `Failed to exchange GitHub App token for ${repository.owner}/${repository.repo}` },
+        { status: 502 },
+      )
+    }
   })
   /**
    * Used by the GitHub action to get GitHub installation access token given user PAT token (used when testing `opencode github run` locally)

packages/function/src/github.ts

@@ -0,0 +1,14 @@
+import type { JWTPayload } from "jose"
+
+export function parseRepositoryClaim(payload: JWTPayload) {
+  const claim = payload.repository
+  if (typeof claim !== "string") throw new Error("Repository claim is missing")
+
+  const parts = claim.split("/")
+  if (parts.length !== 2 || !parts[0] || !parts[1]) throw new Error("Repository claim is invalid")
+
+  return {
+    owner: parts[0],
+    repo: parts[1],
+  }
+}

packages/function/test/github.test.ts

@@ -0,0 +1,39 @@
+import { describe, expect, test } from "bun:test"
+import { parseRepositoryClaim } from "../src/github"
+
+describe("parseRepositoryClaim", () => {
+  test("reads repository identity with a legacy subject", () => {
+    expect(
+      parseRepositoryClaim({
+        repository: "octocat/my-repo",
+        sub: "repo:octocat/my-repo:ref:refs/heads/main",
+      }),
+    ).toEqual({ owner: "octocat", repo: "my-repo" })
+  })
+
+  test("reads repository identity with an immutable subject", () => {
+    expect(
+      parseRepositoryClaim({
+        repository: "octocat/my-repo",
+        sub: "repo:octocat@123456/my-repo@456789:ref:refs/heads/main",
+      }),
+    ).toEqual({ owner: "octocat", repo: "my-repo" })
+  })
+
+  test("does not depend on a repository path in a customized subject", () => {
+    expect(
+      parseRepositoryClaim({
+        repository: "octocat/my-repo",
+        sub: "repository_owner:octocat:repository_visibility:private",
+      }),
+    ).toEqual({ owner: "octocat", repo: "my-repo" })
+  })
+
+  test("rejects a missing repository claim", () => {
+    expect(() => parseRepositoryClaim({})).toThrow("Repository claim is missing")
+  })
+
+  test("rejects an invalid repository claim", () => {
+    expect(() => parseRepositoryClaim({ repository: "octocat" })).toThrow("Repository claim is invalid")
+  })
+})

packages/merman/package.json

@@ -10,6 +10,7 @@
     "./plugin": "./src/plugin.ts"
   },
   "scripts": {
+    "audit:layouts": "bun run script/layout-audit.ts",
     "test": "bun test --timeout 30000 --only-failures",
     "typecheck": "tsgo --noEmit"
   },

packages/merman/script/layout-audit.ts

@@ -0,0 +1,98 @@
+import { mkdir } from "node:fs/promises"
+import { dirname, resolve } from "node:path"
+import {
+  auditAllFixtures,
+  summarizeAudits,
+  worstAudits,
+  type LayoutAudit,
+  type LayoutMetrics,
+} from "../src/test/layout-audit/harness.js"
+
+const outputPath = resolve(import.meta.dir, "../../../tmp/merman-layout-audit.md")
+const startedAt = performance.now()
+const audits = auditAllFixtures()
+const elapsedMs = performance.now() - startedAt
+const summary = summarizeAudits(audits)
+
+function label(audit: LayoutAudit): string {
+  return `${audit.fixture.id} @${audit.viewport}`
+}
+
+function metricTable(items: readonly LayoutAudit[]): string {
+  return [
+    "| Fixture | Viewport | Size | Area | Route length | Bends | Crossings | Shared cells | Overflow |",
+    "| --- | ---: | ---: | ---: | ---: | ---: | ---: | ---: | ---: |",
+    ...items.map(
+      (audit) =>
+        `| \`${audit.fixture.id}\` | ${audit.viewport} | ${audit.metrics.width}x${audit.metrics.height} | ${audit.metrics.area} | ${audit.metrics.routeLength} | ${audit.metrics.bends} | ${audit.metrics.crossings} | ${audit.metrics.sharedRouteCells} | ${audit.metrics.overflow} |`,
+    ),
+  ].join("\n")
+}
+
+function worstSection(metric: keyof LayoutMetrics): string {
+  const worst = worstAudits(audits, metric)
+  return [`### ${metric}`, "", metricTable(worst)].join("\n")
+}
+
+function fixtureSection(audit: LayoutAudit): string {
+  return [
+    `<details${audit.fixture.curated || audit.violations.length > 0 ? " open" : ""}>`,
+    `<summary><code>${label(audit)}</code> · ${audit.metrics.width}x${audit.metrics.height} · area ${audit.metrics.area} · bends ${audit.metrics.bends} · crossings ${audit.metrics.crossings} · overflow ${audit.metrics.overflow}</summary>`,
+    "",
+    ...(audit.violations.length > 0 ? ["Violations:", "", ...audit.violations.map((item) => `- ${item}`), ""] : []),
+    "Source:",
+    "",
+    "```mermaid",
+    audit.fixture.source,
+    "```",
+    "",
+    "Rendered output:",
+    "",
+    "```text",
+    audit.output,
+    "```",
+    "",
+    "</details>",
+  ].join("\n")
+}
+
+const grouped = Map.groupBy(audits, (audit) => `${audit.fixture.kind}/${audit.fixture.family}`)
+const violations = audits.flatMap((audit) => audit.violations.map((violation) => `${label(audit)}: ${violation}`))
+const markdown = [
+  "# Merman Layout Audit",
+  "",
+  `Generated from ${new Set(audits.map((audit) => audit.fixture.id)).size} sources and ${audits.length} layout runs.`,
+  "",
+  `Structural violations: **${violations.length}**`,
+  "",
+  "## Aggregate Metrics",
+  "",
+  "```json",
+  JSON.stringify(summary, null, 2),
+  "```",
+  "",
+  "## Worst Offenders",
+  "",
+  ...(["area", "bends", "crossings", "sharedRouteCells", "overflow"] as const).flatMap((metric) => [
+    worstSection(metric),
+    "",
+  ]),
+  "## Fixtures",
+  "",
+  ...[...grouped.entries()].flatMap(([family, items]) => [
+    `### ${family}`,
+    "",
+    metricTable(items),
+    "",
+    ...items.flatMap((audit) => [fixtureSection(audit), ""]),
+  ]),
+].join("\n")
+
+await mkdir(dirname(outputPath), { recursive: true })
+await Bun.write(outputPath, markdown)
+
+console.log(`Wrote ${audits.length} layout runs to ${outputPath} in ${elapsedMs.toFixed(0)}ms`)
+if (violations.length > 0) {
+  console.error(violations.join("\n"))
+  process.exitCode = 1
+}

packages/merman/src/flowchart/drawing.ts

@@ -43,8 +43,9 @@ function mergeFlowchartCell(
   if (incoming.style !== "edge") return incoming
   if (existing.style === "label") return existing
   if (incoming.char === " ") return existing
-  if ((existing.style !== "edge" && existing.style !== "group") || existing.char === " ") return incoming
-  if (DIAGRAM_ARROW_HEADS.has(existing.char) || DIAGRAM_ARROW_HEADS.has(incoming.char)) return incoming
+  if (existing.style !== "edge" || existing.char === " ") return incoming
+  if (DIAGRAM_ARROW_HEADS.has(existing.char)) return existing
+  if (DIAGRAM_ARROW_HEADS.has(incoming.char)) return incoming
 
   return {
     ...incoming,
@@ -75,22 +76,23 @@ function drawNode(
 ): void {
   const chars = BorderChars[borderStyle]
   const style: FlowchartCellStyle = node.shape === "database" ? "database" : "node"
+  const border: FlowchartCellStyle = node.shape === "database" ? "databaseBorder" : "nodeBorder"
 
   if (node.shape === "decision") {
     drawDiagramDiamond(
       bounds,
-      (x, y, char) => grid.setCell(x, y, char, style),
+      (x, y, char) => grid.setCell(x, y, char, border),
       diagramDiamondCharactersFromBorder(chars),
     )
   } else if (node.shape === "subroutine") {
     fillDiagramFrameInterior(bounds, (x, y) => grid.setCell(x, y, " ", style))
-    drawSubroutineNode(grid, bounds, chars, style)
+    drawSubroutineNode(grid, bounds, chars, border)
   } else if (node.shape === "database") {
     fillDiagramFrameInterior(bounds, (x, y) => grid.setCell(x, y, " ", style))
-    drawDatabaseNode(grid, bounds, chars, style)
+    drawDatabaseNode(grid, bounds, chars, border)
   } else {
     fillDiagramFrameInterior(bounds, (x, y) => grid.setCell(x, y, " ", style))
-    drawDiagramFrame(bounds, chars, (x, y, char) => grid.setCell(x, y, char, style))
+    drawDiagramFrame(bounds, chars, (x, y, char) => grid.setCell(x, y, char, border))
   }
 
   const textTop =
@@ -270,7 +272,7 @@ function drawSourceConnectors(
     const connectorDirection = flowchartDirectionBetween(sourcePoint, connector)
     if (routeDirection && connectorDirection) {
       const cell = grid.getCell(sourcePoint.x, sourcePoint.y)
-      if (cell && cell.style !== "label") {
+      if (cell && cell.style !== "label" && !DIAGRAM_ARROW_HEADS.has(cell.char)) {
         grid.replaceCell(
           sourcePoint.x,
           sourcePoint.y,

packages/merman/src/flowchart/flowchart.test.ts

@@ -1,7 +1,10 @@
 import { describe, expect, test } from "bun:test"
 import { parseColor, TextAttributes } from "@opentui/core"
 import stringWidth from "string-width"
+import { diagramArrowHeadBetween } from "../core/drawing.js"
+import { orthogonalPathPoints } from "../core/geometry.js"
 import { expectDiagram } from "../test/diagram.js"
+import { deploymentArchitectureSource } from "../test/layout-audit/fixtures.js"
 import { drawFlowchartDiagramGrid as drawParsedFlowchartDiagramGrid } from "./drawing.js"
 import {
   DEFAULT_MIN_RANK_GAP,
@@ -35,7 +38,7 @@ function routeRunsAlongHorizontalBorder(
     const from = route.points[index - 1]!
     const to = route.points[index]!
     if (from.y !== to.y || !borderYs.has(from.y)) continue
-    if (Math.max(from.x, to.x) >= left && Math.min(from.x, to.x) <= right) return true
+    if (Math.min(Math.max(from.x, to.x), right) > Math.max(Math.min(from.x, to.x), left)) return true
   }
   return false
 }
@@ -52,7 +55,7 @@ function routeRunsAlongVerticalBorder(
     const from = route.points[index - 1]!
     const to = route.points[index]!
     if (from.x !== to.x || !borderXs.has(from.x)) continue
-    if (Math.max(from.y, to.y) >= top && Math.min(from.y, to.y) <= bottom) return true
+    if (Math.min(Math.max(from.y, to.y), bottom) > Math.max(Math.min(from.y, to.y), top)) return true
   }
   return false
 }
@@ -114,6 +117,111 @@ function boundsIntersect(
   )
 }
 
+function boundsContains(
+  outer: { left: number; top: number; width: number; height: number },
+  inner: { left: number; top: number; width: number; height: number },
+): boolean {
+  return (
+    inner.left >= outer.left &&
+    inner.top >= outer.top &&
+    inner.left + inner.width <= outer.left + outer.width &&
+    inner.top + inner.height <= outer.top + outer.height
+  )
+}
+
+function routesIntersect(
+  left: { points: readonly { x: number; y: number }[] },
+  right: { points: readonly { x: number; y: number }[] },
+): boolean {
+  const occupied = new Set(orthogonalPathPoints(left.points).map((point) => `${point.x}:${point.y}`))
+  return orthogonalPathPoints(right.points).some((point) => occupied.has(`${point.x}:${point.y}`))
+}
+
+function renderedDimensions(output: string): { width: number; height: number } {
+  const lines = output.split("\n")
+  return { width: Math.max(...lines.map((line) => stringWidth(line))), height: lines.length }
+}
+
+function expectResponsiveFlowchartValid(content: string, layoutMaxWidth: number) {
+  const diagram = parseMermaidFlowchartDiagram(content)
+  const options = { compact: true, layoutMaxWidth }
+  const layout = layoutParsedFlowchartDiagram(diagram, options)
+  const grid = drawParsedFlowchartDiagramGrid(diagram, options)
+  const output = renderFlowchartDiagram(content, options)
+  const nodes = [...layout.bounds.values()]
+
+  expect(layout.diagram.direction).toBe("TD")
+  for (let left = 0; left < nodes.length; left++) {
+    for (let right = left + 1; right < nodes.length; right++) {
+      expect(boundsIntersect(nodes[left]!, nodes[right]!)).toBe(false)
+    }
+  }
+  for (const route of layout.routes) {
+    expect(route.points.length).toBeGreaterThanOrEqual(2)
+    for (let index = 1; index < route.points.length; index++) {
+      const from = route.points[index - 1]!
+      const to = route.points[index]!
+      expect(from.x === to.x || from.y === to.y).toBe(true)
+    }
+    expect(terminalPointsTowardBounds(route, layout.bounds.get(route.edge.to)!)).toBe(true)
+    const end = route.points.at(-1)!
+    expect(grid.getCell(end.x, end.y)?.char).toBe(diagramArrowHeadBetween(route.points.at(-2)!, end))
+    if (route.edge.label) expect(output).toContain(route.edge.label)
+  }
+  expectFlowchartRoutesAvoidUnrelatedNodes(layout)
+
+  for (const subgraph of diagram.subgraphs ?? []) {
+    const frame = layout.subgraphBounds.get(subgraph.id)!
+    for (const nodeId of subgraph.nodeIds) expect(boundsContains(frame, layout.bounds.get(nodeId)!)).toBe(true)
+    expect(output).toContain(subgraph.label)
+  }
+  for (const node of layout.bounds.values()) {
+    for (const line of node.lines) expect(output).toContain(line)
+  }
+
+  const widestContent = Math.max(
+    ...nodes.map((node) => node.width),
+    ...layout.routes.flatMap((route) =>
+      route.edge.label ? [flowchartRouteLabelLayout(route, visualLength).width] : [],
+    ),
+  )
+  const dimensions = renderedDimensions(output)
+  expect(Math.max(...output.split("\n").map((line) => stringWidth(line)))).toBeLessThanOrEqual(
+    layoutMaxWidth + widestContent + 4,
+  )
+  return { dimensions, layout, output }
+}
+
+function generatedWideRankFlowchart(count: number): string {
+  const labels = [
+    "地域 gateway Ω",
+    "界面 worker λ",
+    "Long-running synchronization service",
+    "Cache café 🚀",
+    "Audit and observability pipeline",
+    "Provider μ endpoint",
+    "Fallback Ж service",
+    "Archive 数据 lake",
+    "Terminal résumé queue",
+  ]
+  const branches = labels
+    .slice(0, count)
+    .flatMap((label, index) => [
+      `    Hub ${index === 0 ? "-->|dispatch across regions and providers|" : "-->"} N${index}[${label}]`,
+      `    N${index} --> Join`,
+    ])
+  return [
+    "flowchart LR",
+    "  Start[Client α] --> Hub",
+    "  subgraph Services [地域 services Ω]",
+    "    Hub[Dispatch hub]",
+    ...branches,
+    "    Join[Join results]",
+    "  end",
+    "  Join --> Done[Complete ✓]",
+  ].join("\n")
+}
+
 function expectFlowchartRoutesAvoidUnrelatedNodes(layout: ReturnType<typeof layoutFlowchartDiagram>): void {
   for (const route of layout.routes) {
     for (const [id, bounds] of layout.bounds) {
@@ -327,6 +435,52 @@ describe("FlowchartDiagram", () => {
     `)
   })
 
+  test.each(
+    (["LR", "RL", "TD", "TB", "BT"] as const).flatMap((direction) =>
+      [false, true].map((compact) => ({ direction, compact })),
+    ),
+  )(
+    "preserves every target arrowhead after painting $direction routes with compact=$compact",
+    ({ direction, compact }) => {
+      const content = `flowchart ${direction}
+  A[A]
+  B[B]
+  C[C]
+  D[D]
+  A --> A
+  A --> C
+  C --> B`
+      const diagram = parseMermaidFlowchartDiagram(content)
+      const layout = layoutParsedFlowchartDiagram(diagram, { compact })
+      const grid = drawParsedFlowchartDiagramGrid(diagram, { compact })
+
+      for (const route of layout.routes) {
+        const end = route.points.at(-1)!
+        expect(grid.getCell(end.x, end.y)?.char).toBe(diagramArrowHeadBetween(route.points.at(-2)!, end))
+      }
+    },
+  )
+
+  test.each(
+    (["LR", "RL", "TD", "TB", "BT"] as const).flatMap((direction) =>
+      [false, true].map((compact) => ({ direction, compact })),
+    ),
+  )("keeps crossed endpoint-disjoint $direction routes separate with compact=$compact", ({ direction, compact }) => {
+    const layout = layoutFlowchartDiagram(
+      `flowchart ${direction}
+  A[A]
+  B[B]
+  C[C]
+  D[D]
+  A --> C
+  D --> B`,
+      { compact },
+    )
+
+    expect(layout.routes).toHaveLength(2)
+    expect(routesIntersect(layout.routes[0]!, layout.routes[1]!)).toBe(false)
+  })
+
   test("keeps vertical feedback labels clear of unrelated nodes", () => {
     const content = `flowchart TD
   S[Source] --> A[Alpha]
@@ -613,6 +767,7 @@ describe("FlowchartDiagram", () => {
       const loops = layout.routes.filter((route) => route.edge.from === "B" && route.edge.to === "B")
 
       expect(loops).toHaveLength(3)
+      expect(new Set(loops.map((route) => JSON.stringify(route.points))).size).toBe(3)
     },
   )
 
@@ -811,6 +966,119 @@ describe("FlowchartDiagram", () => {
     `)
   })
 
+  test("wraps the real deployment chart responsively without losing content or geometry", () => {
+    const expected = new Map([
+      [60, { width: 82, height: 108 }],
+      [80, { width: 97, height: 85 }],
+      [120, { width: 143, height: 77 }],
+      [160, { width: 163, height: 69 }],
+    ])
+    const results = [...expected].map(([budget, dimensions]) => {
+      const result = expectResponsiveFlowchartValid(deploymentArchitectureSource, budget)
+      expect(result.dimensions).toEqual(dimensions)
+      for (const frame of result.layout.subgraphBounds.values()) {
+        for (const other of result.layout.subgraphBounds.values()) {
+          if (frame !== other) expect(boundsIntersect(frame, other)).toBe(false)
+        }
+      }
+      return result.dimensions
+    })
+
+    for (let index = 1; index < results.length; index++) {
+      expect(results[index - 1]!.width).toBeLessThan(results[index]!.width)
+    }
+  })
+
+  test.each([7, 9])("wraps generated %s-node Unicode subgraph ranks across width targets", (count) => {
+    const results = [60, 80, 120].map(
+      (budget) => expectResponsiveFlowchartValid(generatedWideRankFlowchart(count), budget).dimensions,
+    )
+
+    for (let index = 1; index < results.length; index++) {
+      expect(results[index - 1]!.width).toBeLessThan(results[index]!.width)
+      expect(results[index - 1]!.height).toBeGreaterThanOrEqual(results[index]!.height)
+    }
+  })
+
+  test("keeps responsive local-direction subgraphs clear of sibling nodes", () => {
+    const layout = layoutFlowchartDiagram(
+      `flowchart BT
+  N0[Outside zero]
+  subgraph Outer
+    N2[Two]
+    subgraph Inner
+      direction LR
+      N3[Three]
+      N4[Four]
+    end
+    N5[X]
+  end
+  N7[Outside seven]
+  N7 --> N2
+  N2 -->|label 6| N5
+  N5 --> N4
+  N0 --> N7`,
+      { compact: true, layoutMaxWidth: 35 },
+    )
+    const nodes = [...layout.bounds.values()]
+
+    for (let left = 0; left < nodes.length; left++) {
+      for (let right = left + 1; right < nodes.length; right++) {
+        expect(boundsIntersect(nodes[left]!, nodes[right]!)).toBe(false)
+      }
+    }
+  })
+
+  test("keeps responsive sibling subgraph frames and long titles disjoint", () => {
+    const layout = layoutFlowchartDiagram(
+      `flowchart TD
+  subgraph Parent
+    direction LR
+    subgraph Left [A deliberately long left group title]
+      direction LR
+      A1[One] --> A2[Two]
+    end
+    subgraph Right [A deliberately long right group title]
+      direction LR
+      B1[Three] --> B2[Four]
+    end
+    A2 --> B1
+  end`,
+      { compact: true, layoutMaxWidth: 35 },
+    )
+
+    expect(boundsIntersect(layout.subgraphBounds.get("Left")!, layout.subgraphBounds.get("Right")!)).toBe(false)
+  })
+
+  test("does not change parallel routes for a non-binding width target", () => {
+    const diagram = parseMermaidFlowchartDiagram(`flowchart TD
+  A[A] -->|one| B[B]
+  A -->|two| B`)
+    const unconstrained = layoutParsedFlowchartDiagram(diagram, { compact: true })
+    const nonBinding = layoutParsedFlowchartDiagram(diagram, { compact: true, layoutMaxWidth: 1_000 })
+
+    expect(nonBinding.routes.map((route) => route.points)).toEqual(unconstrained.routes.map((route) => route.points))
+  })
+
+  test("keeps responsive fan-out labels inside the width target", () => {
+    const content = `flowchart TD
+  subgraph Group
+    S[Source]
+    S -->|route 0 detail| N0[Node 0]
+    S -->|route 1 detail| N1[Node 1]
+    S -->|route 2 detail| N2[Node 2]
+    S -->|route 3 detail| N3[Node 3]
+  end`
+    const layout = layoutFlowchartDiagram(content, { compact: true, layoutMaxWidth: 30 })
+    const output = renderFlowchartDiagram(content, { compact: true, layoutMaxWidth: 30 })
+
+    for (const route of layout.routes) {
+      const label = flowchartRouteLabelLayout(route, visualLength)
+      expect(label.point.x + label.width).toBeLessThanOrEqual(30)
+    }
+    expect(Math.max(...output.split("\n").map((line) => stringWidth(line)))).toBeLessThanOrEqual(34)
+  })
+
   test("parses Mermaid flowchart nodes and standard arrows", () => {
     const diagram = parseMermaidFlowchartDiagram(`
 flowchart TD
@@ -1349,6 +1617,22 @@ flowchart LR
     expect(output).not.toContain("<br")
   })
 
+  test.each(
+    (["TD", "BT"] as const).flatMap((direction) =>
+      [false, true].flatMap((compact) => [2, 4].map((lines) => ({ direction, compact, lines }))),
+    ),
+  )(
+    "keeps $lines-line $direction labels off both terminal rows with compact=$compact",
+    ({ direction, compact, lines }) => {
+      const label = Array.from({ length: lines }, (_, index) => `line ${index + 1}`).join("<br/>")
+      const route = layoutFlowchartDiagram(`flowchart ${direction}\n  A[A] -->|${label}| B[B]`, { compact }).routes[0]!
+      const layout = flowchartRouteLabelLayout(route, visualLength)
+      const terminals = new Set([route.points[0]!.y, route.points.at(-1)!.y])
+
+      for (let y = layout.point.y; y < layout.point.y + layout.height; y++) expect(terminals.has(y)).toBe(false)
+    },
+  )
+
   test("expands canvas for multiline back-edge labels", () => {
     const output = renderFlowchartDiagram(`flowchart TD
   A --> B
@@ -1393,10 +1677,10 @@ graph LR
     expect(output).toContain("API")
     expect(output).toContain("DB")
     expect(output).toContain("╭─ Web App ")
-    expect(output.split("\n").find((line) => line.includes("API") && line.includes("DB"))).toContain("┼")
+    expect(output.split("\n").find((line) => line.includes("API") && line.includes("DB"))).not.toContain("┼")
   })
 
-  test("merges horizontal routes through vertical subgraph borders", () => {
+  test("breaks vertical subgraph borders where horizontal routes pass through", () => {
     const content = `flowchart LR
   Outside[Outside] --> Inside
   subgraph Group
@@ -1408,13 +1692,14 @@ graph LR
     const group = layout.subgraphBounds.get("Group")!
     const crossing = { x: group.left, y: layout.routes[0]!.points.at(-1)!.y }
 
-    expect(grid.getCell(crossing.x, crossing.y)?.char).toBe("┼")
+    expect(grid.getCell(crossing.x, crossing.y)?.char).toBe("─")
+    expect(grid.getCell(crossing.x, crossing.y)?.style).not.toBe("group")
     expect(grid.getCell(crossing.x - 1, crossing.y)?.char).toBe("─")
     expect(grid.getCell(crossing.x, crossing.y - 1)?.char).toBe("│")
     expect(grid.getCell(crossing.x, crossing.y + 1)?.char).toBe("│")
   })
 
-  test("merges vertical routes through horizontal subgraph borders", () => {
+  test("breaks horizontal subgraph borders where vertical routes pass through", () => {
     const content = `flowchart TD
   Outside[Outside] --> Inside
   subgraph Outer [O]
@@ -1428,7 +1713,8 @@ graph LR
     const outer = layout.subgraphBounds.get("Outer")!
     const crossing = { x: layout.routes[0]!.points[0]!.x, y: outer.top }
 
-    expect(grid.getCell(crossing.x, crossing.y)?.char).toBe("┼")
+    expect(grid.getCell(crossing.x, crossing.y)?.char).toBe("│")
+    expect(grid.getCell(crossing.x, crossing.y)?.style).not.toBe("group")
     expect(grid.getCell(crossing.x - 1, crossing.y)?.char).toBe("─")
     expect(grid.getCell(crossing.x + 1, crossing.y)?.char).toBe("─")
     expect(grid.getCell(crossing.x, crossing.y - 1)?.char).toBe("│")
@@ -1466,21 +1752,20 @@ graph LR
     expect(output).not.toContain("<br")
   })
 
-  test("merges transition lines through subgraph frame borders", () => {
-    const output = renderFlowchartDiagram(`
-flowchart TD
-  subgraph Verse [verse]
-    direction LR
-    A[A] --> B[B]
-    C[C] --> D[D]
+  test("keeps long Unicode subgraph titles from replacing entering arrowheads", () => {
+    const content = `flowchart TD
+  U[Up] --> A
+  subgraph G [界界界界界界]
+    A[A]
   end
-  B --> Join
-  D --> Join
-`)
-    const crossingLines = output.split("\n").filter((line) => line.includes("Join") || line.includes("├"))
+  A --> D[Down]`
+    const diagram = parseMermaidFlowchartDiagram(content)
+    const layout = layoutParsedFlowchartDiagram(diagram, { compact: true })
+    const grid = drawParsedFlowchartDiagramGrid(diagram, { compact: true })
+    const entry = layout.routes.find((route) => route.edge.from === "U")!
+    const end = entry.points.at(-1)!
 
-    expect(output).toContain(" verse ")
-    expect(crossingLines.join("\n").match(/┼/g)).toHaveLength(2)
+    expect(grid.getCell(end.x, end.y)?.char).toBe(diagramArrowHeadBetween(entry.points.at(-2)!, end))
   })
 
   test("lays out subgraph-local directions independently from the outer flow", () => {
@@ -1612,6 +1897,65 @@ flowchart TD
     }
   })
 
+  test("keeps nested local-direction layouts rigid across direction and compact matrices", () => {
+    const directions = ["LR", "RL", "TD", "BT"] as const
+    for (const global of directions) {
+      for (const outer of directions) {
+        for (const inner of directions) {
+          for (const compact of [false, true]) {
+            const layout = layoutFlowchartDiagram(
+              `flowchart ${global}
+  X[X] --> A
+  subgraph Outer [Outer]
+    direction ${outer}
+    subgraph Inner [Inner]
+      direction ${inner}
+      A[A] --> B[B]
+    end
+    B --> C[C]
+  end
+  C --> Y[Y]`,
+              { compact },
+            )
+            const nodes = [...layout.bounds.values()]
+            const innerFrame = layout.subgraphBounds.get("Inner")!
+            const outerFrame = layout.subgraphBounds.get("Outer")!
+            const a = layout.bounds.get("A")!
+            const b = layout.bounds.get("B")!
+            const c = layout.bounds.get("C")!
+
+            for (let left = 0; left < nodes.length; left++) {
+              for (let right = left + 1; right < nodes.length; right++) {
+                expect(boundsIntersect(nodes[left]!, nodes[right]!)).toBe(false)
+              }
+            }
+            expect(boundsContains(innerFrame, a)).toBe(true)
+            expect(boundsContains(innerFrame, b)).toBe(true)
+            expect(boundsContains(outerFrame, innerFrame)).toBe(true)
+            expect(boundsContains(outerFrame, c)).toBe(true)
+            expect(layout.routes.every((route) => route.points.length >= 2)).toBe(true)
+            expectFlowchartRoutesAvoidUnrelatedNodes(layout)
+            for (const frame of layout.subgraphBounds.values()) {
+              for (const route of layout.routes) {
+                expect(routeRunsAlongHorizontalBorder(route, frame)).toBe(false)
+                expect(routeRunsAlongVerticalBorder(route, frame)).toBe(false)
+              }
+            }
+
+            if (inner === "LR") expect(b.left).toBeGreaterThan(a.left)
+            if (inner === "RL") expect(b.left).toBeLessThan(a.left)
+            if (inner === "TD") expect(b.top).toBeGreaterThan(a.top)
+            if (inner === "BT") expect(b.top).toBeLessThan(a.top)
+            if (outer === "LR") expect(c.centerX).toBeGreaterThan(b.centerX)
+            if (outer === "RL") expect(c.centerX).toBeLessThan(b.centerX)
+            if (outer === "TD") expect(c.centerY).toBeGreaterThan(b.centerY)
+            if (outer === "BT") expect(c.centerY).toBeLessThan(b.centerY)
+          }
+        }
+      }
+    }
+  })
+
   test("compacts stacked subgraph-local direction rows", () => {
     const layout = layoutFlowchartDiagram(`
 flowchart TD
@@ -2037,8 +2381,10 @@ flowchart LR
   test("applies the global flowchart StyledText theme", () => {
     const grid = drawFlowchartDiagramGrid("flowchart LR\n  A[Alpha] --> B[Beta]")
     const node = parseColor("#ff0000")
-    const styled = renderGridStyledText(grid, resolveFlowchartStyleColors({ node }))
+    const nodeBorder = parseColor("#0000ff")
+    const styled = renderGridStyledText(grid, resolveFlowchartStyleColors({ node, nodeBorder }))
 
     expect(styled.chunks.some((chunk) => chunk.text.includes("Alpha") && chunk.fg?.equals(node))).toBe(true)
+    expect(styled.chunks.some((chunk) => chunk.text.includes("╭") && chunk.fg?.equals(nodeBorder))).toBe(true)
   })
 })

packages/merman/src/flowchart/labels.ts

@@ -18,6 +18,7 @@ const LABEL_BUS_CLEARANCE = 3
 const LABEL_NODE_CLEARANCE = 2
 const LABEL_LINE_CLEARANCE = 2
 const LABEL_PADDING = 1
+const LABEL_TERMINAL_CLEARANCE = 1
 
 export interface FlowchartEdgeLabelLayout {
   lines: string[]
@@ -63,6 +64,11 @@ function segmentLabelPoint(segment: DiagramSegment, labelWidth: number, labelHei
     return clampPoint(shiftPoint(shiftPoint(segment.from, segment.direction, LABEL_LINE_CLEARANCE), "up", labelHeight))
   }
 
+  const slot = insetSpan(segmentSpan(segment), LABEL_TERMINAL_CLEARANCE)
+  if (spanCapacity(slot) >= labelHeight) {
+    return clampPoint(point(segment.from.x + 1, centeredSpanStart(slot, labelHeight)))
+  }
+
   const center = shiftPoint(pointOnSegment(segment, midpoint(segmentSpan(segment))), "right")
   return clampPoint(shiftPoint(center, "up", Math.floor((labelHeight - 1) / 2)))
 }

packages/merman/src/flowchart/layout.ts

@@ -14,7 +14,7 @@ import {
   flowchartVerticalBranchLabelGap,
 } from "./labels.js"
 import type { FlowchartDiagramRenderOptions } from "./options.js"
-import { routeFlowchartEdges } from "./routing.js"
+import { avoidFlowchartFrameBorders, routeFlowchartEdges } from "./routing.js"
 import type {
   FlowchartDiagram,
   FlowchartDirection,
@@ -23,6 +23,7 @@ import type {
   FlowchartNode,
   FlowchartNodeBounds,
   FlowchartNodeSize,
+  FlowchartPoint,
   FlowchartSubgraphBounds,
 } from "./types.js"
 
@@ -364,7 +365,8 @@ function layoutRankedNodes(
   sizes: ReadonlyMap<string, FlowchartNodeSize>,
   minNodeGap: number,
   requestedMinRankGap: number,
-): Map<string, FlowchartNodeBounds> {
+  targetWidth?: number,
+): { bounds: Map<string, FlowchartNodeBounds>; wrapped: boolean } {
   const horizontal = isHorizontalDirection(direction)
   const ranks = rankNodes(diagram)
   const maxRank = Math.max(0, ...ranks.values())
@@ -406,6 +408,7 @@ function layoutRankedNodes(
   const horizontalGaps = horizontal ? horizontalRankGaps(diagram, normalizedRanks, rankKeys, requestedMinRankGap) : []
   const verticalGaps = horizontal ? [] : verticalRankGaps(diagram, normalizedRanks, rankKeys, requestedMinRankGap)
   const bounds = new Map<string, FlowchartNodeBounds>()
+  let wrapped = false
 
   if (horizontal) {
     const columnWidths = rankKeys.map((rank) =>
@@ -442,68 +445,141 @@ function layoutRankedNodes(
       x += columnWidth + (horizontalGaps[rankIndex] ?? 0)
     }
   } else {
-    const rowHeights = rankKeys.map((rank) =>
-      Math.max(...ranksByIndex.get(rank)!.map((node) => sizes.get(node.id)!.height)),
-    )
-    const rowWidths = rankKeys.map((rank) => {
+    const rankBands = rankKeys.map((rank) => {
       const nodes = ranksByIndex.get(rank)!
-      return (
+      const roomyNodeGap = verticalNodeGap(rank)
+      const naturalWidth =
         nodes.reduce((total, node) => total + sizes.get(node.id)!.width, 0) +
-        Math.max(0, nodes.length - 1) * verticalNodeGap(rank)
+        Math.max(0, nodes.length - 1) * roomyNodeGap
+      const labeledEdges = diagram.edges.filter(
+        (edge) => edge.label && (normalizedRanks.get(edge.from) === rank || normalizedRanks.get(edge.to) === rank),
       )
-    })
-    const canvasWidth = Math.max(1, ...rowWidths)
-    let y = 0
-    for (let rankIndex = 0; rankIndex < rankKeys.length; rankIndex++) {
-      const rank = rankKeys[rankIndex]!
-      const nodes = ranksByIndex.get(rank)!
-      const rowHeight = rowHeights[rankIndex]!
-      const nodeGap = verticalNodeGap(rank)
-      let x = Math.floor((canvasWidth - rowWidths[rankIndex]!) / 2)
+      const needsLabelLanes =
+        labeledEdges.length > 1 &&
+        labeledEdges.some((edge) => {
+          const targets = new Set(
+            labeledEdges.filter((candidate) => candidate.from === edge.from).map((candidate) => candidate.to),
+          )
+          const sources = new Set(
+            labeledEdges.filter((candidate) => candidate.to === edge.to).map((candidate) => candidate.from),
+          )
+          const grouped = (ids: readonly string[]) =>
+            !diagram.subgraphs?.length ||
+            diagram.subgraphs.some((subgraph) => ids.every((id) => subgraph.nodeIds.includes(id)))
+          return (
+            (targets.size > 1 && grouped([edge.from, ...targets])) ||
+            (sources.size > 1 && grouped([edge.to, ...sources]))
+          )
+        })
+      const nodeGap =
+        targetWidth !== undefined && naturalWidth > targetWidth && !needsLabelLanes ? minNodeGap : roomyNodeGap
+      const bands: { nodes: FlowchartNode[]; width: number; height: number }[] = []
       for (const node of nodes) {
         const size = sizes.get(node.id)!
-        const top = y + Math.floor((rowHeight - size.height) / 2)
-        bounds.set(node.id, {
-          id: node.id,
-          ...size,
-          left: x,
-          top,
-          centerX: x + Math.floor(size.width / 2),
-          centerY: top + Math.floor(size.height / 2),
-        })
-        x += size.width + nodeGap
+        const current = bands.at(-1)
+        const width = current ? current.width + nodeGap + size.width : size.width
+        if (current && targetWidth !== undefined && width > targetWidth) {
+          wrapped = true
+          bands.push({ nodes: [node], width: size.width, height: size.height })
+          continue
+        }
+        if (!current) {
+          bands.push({ nodes: [node], width: size.width, height: size.height })
+          continue
+        }
+        current.nodes.push(node)
+        current.width = width
+        current.height = Math.max(current.height, size.height)
       }
-      y += rowHeight + (verticalGaps[rankIndex] ?? 0)
+      return { bands, nodeGap }
+    })
+    const canvasWidth = Math.max(1, ...rankBands.flatMap((rank) => rank.bands.map((band) => band.width)))
+    let y = 0
+    for (let rankIndex = 0; rankIndex < rankKeys.length; rankIndex++) {
+      const rank = rankBands[rankIndex]!
+      for (const [bandIndex, band] of rank.bands.entries()) {
+        let x = Math.floor((canvasWidth - band.width) / 2)
+        for (const node of band.nodes) {
+          const size = sizes.get(node.id)!
+          const top = y + Math.floor((band.height - size.height) / 2)
+          bounds.set(node.id, {
+            id: node.id,
+            ...size,
+            left: x,
+            top,
+            centerX: x + Math.floor(size.width / 2),
+            centerY: top + Math.floor(size.height / 2),
+          })
+          x += size.width + rank.nodeGap
+        }
+        y += band.height + (bandIndex < rank.bands.length - 1 ? minNodeGap : 0)
+      }
+      y += verticalGaps[rankIndex] ?? 0
     }
   }
 
-  return bounds
+  return { bounds, wrapped }
 }
 
 function layoutLocalSubgraphDirections(
   diagram: FlowchartDiagram,
   nodeBounds: Map<string, FlowchartNodeBounds>,
-  sizes: ReadonlyMap<string, FlowchartNodeSize>,
   minNodeGap: number,
   requestedMinRankGap: number,
-): void {
+  targetWidth?: number,
+): boolean {
+  let wrapped = false
   for (const subgraph of [...(diagram.subgraphs ?? [])].reverse()) {
     if (!subgraph.direction || subgraph.direction === diagram.direction) continue
-    const nodeIds = new Set(subgraph.nodeIds)
-    const nodes = diagram.nodes.filter((node) => nodeIds.has(node.id))
-    if (nodes.length === 0) continue
+    const childSubgraphs = (diagram.subgraphs ?? []).filter((child) => child.parentId === subgraph.id)
+    const coveredNodeIds = new Set(childSubgraphs.flatMap((child) => [...collectSubgraphNodeIds(diagram, child.id)]))
+    const items = [
+      ...childSubgraphs.flatMap((child) => {
+        const nodeIds = [...collectSubgraphNodeIds(diagram, child.id)]
+        const content = boundsFromChildren(nodeIds.flatMap((id) => nodeBounds.get(id) ?? []))
+        const bounds = content ? subgraphBoundFromChildren(child.id, child.label, [content]) : undefined
+        return bounds ? [{ id: `subgraph:${child.id}`, nodeIds, bounds, childId: child.id }] : []
+      }),
+      ...subgraph.nodeIds.flatMap((id) => {
+        if (coveredNodeIds.has(id)) return []
+        const bounds = nodeBounds.get(id)
+        return bounds ? [{ id, nodeIds: [id], bounds, childId: undefined }] : []
+      }),
+    ]
+    if (items.length === 0) continue
 
-    const currentBounds = boundsFromChildren(nodes.flatMap((node) => nodeBounds.get(node.id) ?? []))
+    const currentBounds = boundsFromChildren(items.map((item) => item.bounds))
     if (!currentBounds) continue
 
+    const itemByEndpoint = new Map<string, string>()
+    for (const item of items) {
+      for (const nodeId of item.nodeIds) itemByEndpoint.set(nodeId, item.id)
+      if (item.childId) itemByEndpoint.set(item.childId, item.id)
+    }
+    const nodes = items.map((item): FlowchartNode => ({ id: item.id, label: item.id, shape: "box" }))
     const localDiagram: FlowchartDiagram = {
       direction: subgraph.direction,
       nodes,
-      edges: diagram.edges.filter((edge) => nodeIds.has(edge.from) && nodeIds.has(edge.to)),
+      edges: diagram.edges.flatMap((edge) => {
+        const from = itemByEndpoint.get(edge.from)
+        const to = itemByEndpoint.get(edge.to)
+        return from && to && from !== to ? [{ ...edge, from, to }] : []
+      }),
       subgraphs: [],
     }
-    const localNodeGap = isHorizontalDirection(subgraph.direction) ? Math.max(4, minNodeGap - 1) : minNodeGap
-    const localBounds = layoutRankedNodes(localDiagram, subgraph.direction, sizes, localNodeGap, requestedMinRankGap)
+    const itemSizes = new Map(
+      items.map((item) => [item.id, { width: item.bounds.width, height: item.bounds.height, lines: [item.id] }]),
+    )
+    const localLayout = layoutRankedNodes(
+      localDiagram,
+      subgraph.direction,
+      itemSizes,
+      Math.max(minNodeGap, SUBGRAPH_PADDING_X * 2 + 1),
+      requestedMinRankGap,
+      targetWidth,
+    )
+    const localBounds = localLayout.bounds
+    wrapped ||= localLayout.wrapped
     const localExtent = boundsFromChildren([...localBounds.values()])
     if (!localExtent) continue
 
@@ -512,11 +588,66 @@ function layoutLocalSubgraphDirections(
     const dx = targetLeft - localExtent.left
     const dy = targetTop - localExtent.top
 
-    for (const [nodeId, bound] of localBounds) {
-      translateBounds(bound, dx, dy)
-      nodeBounds.set(nodeId, bound)
+    const translations = new Map<string, { dx: number; dy: number }>()
+    for (const item of items) {
+      const bound = localBounds.get(item.id)!
+      const itemDx = bound.left + dx - item.bounds.left
+      const itemDy = bound.top + dy - item.bounds.top
+      for (const nodeId of item.nodeIds) translations.set(nodeId, { dx: itemDx, dy: itemDy })
+    }
+
+    let groupOffset = { x: 0, y: 0 }
+    if (targetWidth !== undefined) {
+      const localNodeIds = new Set(translations.keys())
+      const external = [...nodeBounds.entries()].filter(([id]) => !localNodeIds.has(id)).map(([, bound]) => bound)
+      const overlaps = (offset: FlowchartPoint) =>
+        [...translations].some(([id, translation]) => {
+          const bound = nodeBounds.get(id)!
+          const left = bound.left + translation.dx + offset.x
+          const top = bound.top + translation.dy + offset.y
+          return external.some(
+            (other) =>
+              left < other.left + other.width + minNodeGap &&
+              left + bound.width + minNodeGap > other.left &&
+              top < other.top + other.height + minNodeGap &&
+              top + bound.height + minNodeGap > other.top,
+          )
+        })
+      if (overlaps(groupOffset)) {
+        const vertical = !isHorizontalDirection(diagram.direction)
+        const sign = diagram.direction === "RL" || diagram.direction === "BT" ? -1 : 1
+        let found = false
+        search: for (let distance = 1; distance < 1_000; distance++) {
+          const candidates = vertical
+            ? [
+                { x: 0, y: sign * distance },
+                { x: 0, y: -sign * distance },
+                { x: distance, y: 0 },
+                { x: -distance, y: 0 },
+              ]
+            : [
+                { x: sign * distance, y: 0 },
+                { x: -sign * distance, y: 0 },
+                { x: 0, y: distance },
+                { x: 0, y: -distance },
+              ]
+          for (const candidate of candidates) {
+            if (overlaps(candidate)) continue
+            groupOffset = candidate
+            found = true
+            break search
+          }
+        }
+        if (!found) throw new Error(`Subgraph ${subgraph.id} has no collision-free responsive position`)
+      }
+    }
+
+    for (const [nodeId, translation] of translations) {
+      const nodeBound = nodeBounds.get(nodeId)
+      if (nodeBound) translateBounds(nodeBound, translation.dx + groupOffset.x, translation.dy + groupOffset.y)
     }
   }
+  return wrapped
 }
 
 function edgeDirection(diagram: FlowchartDiagram, edge: FlowchartEdge): FlowchartDirection {
@@ -601,6 +732,7 @@ function separateTopLevelItems(
   nodeBounds: Map<string, FlowchartNodeBounds>,
   subgraphBounds: ReadonlyMap<string, FlowchartSubgraphBounds>,
   gap: number,
+  targetWidth?: number,
 ): boolean {
   const hasLocalDirection = (diagram.subgraphs ?? []).some(
     (subgraph) => subgraph.direction && subgraph.direction !== diagram.direction,
@@ -734,6 +866,35 @@ function separateTopLevelItems(
       crossCursor = start + shift + size + gap
     }
   }
+  if (targetWidth !== undefined && !horizontal) {
+    const intersects = (left: (typeof items)[number], right: (typeof items)[number]): boolean =>
+      [...left.nodeIds].some((leftId) => {
+        const leftBounds = nodeBounds.get(leftId)!
+        return [...right.nodeIds].some((rightId) => {
+          const rightBounds = nodeBounds.get(rightId)!
+          return (
+            leftBounds.left <= rightBounds.left + rightBounds.width - 1 &&
+            leftBounds.left + leftBounds.width - 1 >= rightBounds.left &&
+            leftBounds.top <= rightBounds.top + rightBounds.height - 1 &&
+            leftBounds.top + leftBounds.height - 1 >= rightBounds.top
+          )
+        })
+      })
+    for (let rightIndex = 1; rightIndex < items.length; rightIndex++) {
+      const right = items[rightIndex]!
+      for (let leftIndex = 0; leftIndex < rightIndex; leftIndex++) {
+        const left = items[leftIndex]!
+        if (!intersects(left, right)) continue
+        const leftBounds = boundsFromChildren([...left.nodeIds].map((id) => nodeBounds.get(id)!))!
+        const rightBounds = boundsFromChildren([...right.nodeIds].map((id) => nodeBounds.get(id)!))!
+        const shift = reversed
+          ? leftBounds.top - gap - (rightBounds.top + rightBounds.height)
+          : leftBounds.top + leftBounds.height + gap - rightBounds.top
+        moved ||= shift !== 0
+        moveItem(right, 0, shift)
+      }
+    }
+  }
   return moved
 }
 
@@ -771,6 +932,7 @@ function layoutFlowchartWithDirection(
   sourceDiagram: FlowchartDiagram,
   options: FlowchartDiagramRenderOptions,
   direction: FlowchartDirection,
+  responsiveFallback = false,
 ): FlowchartLayout {
   const diagram = direction === sourceDiagram.direction ? sourceDiagram : { ...sourceDiagram, direction }
   const horizontal = isHorizontalDirection(direction)
@@ -786,29 +948,65 @@ function layoutFlowchartWithDirection(
         : DEFAULT_MIN_VERTICAL_RANK_GAP,
   )
   const sizes = new Map(diagram.nodes.map((node) => [node.id, nodeSize(node)]))
-  const bounds = layoutRankedNodes(diagram, direction, sizes, minNodeGap, requestedMinRankGap)
-  layoutLocalSubgraphDirections(diagram, bounds, sizes, minNodeGap, requestedMinRankGap)
+  const targetWidth =
+    !horizontal && options.layoutMaxWidth !== undefined && Number.isFinite(options.layoutMaxWidth)
+      ? Math.max(1, Math.trunc(options.layoutMaxWidth))
+      : undefined
+  const ranked = layoutRankedNodes(diagram, direction, sizes, minNodeGap, requestedMinRankGap, targetWidth)
+  const bounds = ranked.bounds
+  const responsive = layoutLocalSubgraphDirections(diagram, bounds, minNodeGap, requestedMinRankGap, targetWidth)
+  const directionAligned = responsiveFallback || responsive || ranked.wrapped
 
   const subgraphs = diagram.subgraphs ?? []
   let subgraphBounds = new Map<string, FlowchartSubgraphBounds>()
   let routes: FlowchartEdgeRoute[]
   if (subgraphs.length === 0) {
-    routes = routeFlowchartEdges(diagram, bounds, (edge) => edgeDirection(diagram, edge))
+    routes = routeFlowchartEdges(
+      diagram,
+      bounds,
+      (edge) => edgeDirection(diagram, edge),
+      undefined,
+      targetWidth,
+      directionAligned,
+    )
   } else {
-    routes = routeFlowchartEdges(diagram, bounds, (edge) => edgeDirection(diagram, edge))
+    routes = routeFlowchartEdges(
+      diagram,
+      bounds,
+      (edge) => edgeDirection(diagram, edge),
+      undefined,
+      targetWidth,
+      directionAligned,
+    )
     subgraphBounds = layoutSubgraphs(diagram, bounds, routes)
     const moved = separateTopLevelItems(
       diagram,
       bounds,
       subgraphBounds,
       Math.max(1, Math.floor(requestedMinRankGap / 2)),
+      targetWidth,
     )
     if (moved) {
-      routes = routeFlowchartEdges(diagram, bounds, (edge) => edgeDirection(diagram, edge))
+      routes = routeFlowchartEdges(
+        diagram,
+        bounds,
+        (edge) => edgeDirection(diagram, edge),
+        undefined,
+        targetWidth,
+        directionAligned,
+      )
       subgraphBounds = layoutSubgraphs(diagram, bounds, routes)
     }
-    routes = routeFlowchartEdges(diagram, bounds, (edge) => edgeDirection(diagram, edge), subgraphBounds)
+    routes = routeFlowchartEdges(
+      diagram,
+      bounds,
+      (edge) => edgeDirection(diagram, edge),
+      subgraphBounds,
+      targetWidth,
+      directionAligned,
+    )
     subgraphBounds = layoutSubgraphs(diagram, bounds, routes)
+    avoidFlowchartFrameBorders(routes, bounds, subgraphBounds)
   }
   freezeRouteLabelPoints(routes)
   const allBounds = [...bounds.values(), ...subgraphBounds.values(), ...routeRenderBounds(routes)]
@@ -834,5 +1032,5 @@ export function layoutFlowchartDiagram(
   if (!isHorizontalDirection(direction) || maxWidth === undefined || !Number.isFinite(maxWidth)) return layout
   if (layout.width <= Math.max(1, Math.trunc(maxWidth))) return layout
 
-  return layoutFlowchartWithDirection(sourceDiagram, options, direction === "RL" ? "BT" : "TD")
+  return layoutFlowchartWithDirection(sourceDiagram, options, direction === "RL" ? "BT" : "TD", true)
 }

packages/merman/src/flowchart/options.ts

@@ -7,6 +7,6 @@ export interface FlowchartDiagramRenderOptions {
   borderStyle?: BorderStyle
   minNodeGap?: number
   minRankGap?: number
-  /** Fold oversized horizontal layouts vertically when their rendered width exceeds this limit. */
+  /** Target rendered width. Oversized horizontal layouts fold vertically and broad vertical ranks wrap. */
   layoutMaxWidth?: number
 }

packages/merman/src/flowchart/routing.ts

@@ -11,9 +11,11 @@ import {
   lane,
   oppositeSide,
   orthogonalPath,
+  orthogonalPathPoints,
   pathThrough,
   pathViaLane,
   segmentBetween,
+  segmentSpan,
   sideForDirection,
   snapCoordinate,
   shiftPoint,
@@ -138,11 +140,11 @@ function horizontalEdgePath(
   })
 }
 
-function selfEdgePath(bounds: FlowchartNodeBounds): FlowchartPoint[] {
+function selfEdgePath(bounds: FlowchartNodeBounds, laneOffset = 0): FlowchartPoint[] {
   const start = boundsSidePoint(bounds, "right")
   const end = boundsSidePoint(bounds, "bottom")
-  const rightLaneX = bounds.left + bounds.width + BUS_CLEARANCE
-  const bottomLaneY = bounds.top + bounds.height + 1
+  const rightLaneX = bounds.left + bounds.width + BUS_CLEARANCE + laneOffset
+  const bottomLaneY = bounds.top + bounds.height + 1 + laneOffset
   return [start, { x: rightLaneX, y: start.y }, { x: rightLaneX, y: bottomLaneY }, { x: end.x, y: bottomLaneY }, end]
 }
 
@@ -522,6 +524,8 @@ function routeVerticalFanIn(
 function routeParallelEdges(
   diagram: FlowchartDiagram,
   bounds: Map<string, FlowchartNodeBounds>,
+  directionForEdge: (edge: FlowchartEdge) => FlowchartDirection,
+  directionAligned: boolean,
   handled: Set<FlowchartEdge>,
   routes: FlowchartEdgeRoute[],
 ): void {
@@ -530,8 +534,18 @@ function routeParallelEdges(
     if (edges.length < 2) continue
     const from = bounds.get(edges[0]!.from)
     const to = bounds.get(edges[0]!.to)
-    if (!from || !to || from.id === to.id) continue
-    const parallelAxis = parallelLaneAxis(from, to)
+    if (!from || !to) continue
+    if (from.id === to.id) {
+      let laneOffset = 0
+      for (const edge of edges) {
+        routes.push({ edge, points: selfEdgePath(from, laneOffset) })
+        handled.add(edge)
+        laneOffset++
+      }
+      continue
+    }
+    const parallelAxis =
+      directionAligned && isVerticalDirection(directionForEdge(edges[0]!)) ? "x" : parallelLaneAxis(from, to)
     let previousRoute: FlowchartEdgeRoute | undefined
     for (const edge of edges) {
       const height = labelHeight(edge)
@@ -539,7 +553,7 @@ function routeParallelEdges(
         parallelAxis === "x"
           ? previousRoute
             ? rightRenderExtent(previousRoute) + NODE_CLEARANCE
-            : Math.max(boundsSidePoint(from, "right").x, boundsSidePoint(to, "right").x)
+            : Math.max(boundsSidePoint(from, "right").x, boundsSidePoint(to, "right").x) + (directionAligned ? 1 : 0)
           : previousRoute
             ? Math.max(...previousRoute.points.map((point) => point.y)) + (height > 1 ? height + 1 : 1)
             : Math.max(boundsSidePoint(from, "bottom").y, boundsSidePoint(to, "bottom").y) + (height > 1 ? height : 0)
@@ -795,6 +809,69 @@ function routeIntersectsLabels(route: FlowchartEdgeRoute, labels: readonly Flowc
   )
 }
 
+function pathsIntersect(left: readonly FlowchartPoint[], right: readonly FlowchartPoint[]): boolean {
+  const occupied = new Set(orthogonalPathPoints(left).map((point) => `${point.x}:${point.y}`))
+  return orthogonalPathPoints(right).some((point) => occupied.has(`${point.x}:${point.y}`))
+}
+
+function endpointDisjoint(left: FlowchartEdge, right: FlowchartEdge): boolean {
+  return left.from !== right.from && left.from !== right.to && left.to !== right.from && left.to !== right.to
+}
+
+function endpointConflictsWithRoutes(route: FlowchartEdgeRoute, otherRoutes: readonly FlowchartEdgeRoute[]): boolean {
+  const source = route.points[0]
+  const target = route.points.at(-1)
+  if (!source || !target) return false
+  return otherRoutes.some((other) => {
+    const otherSource = other.points[0]
+    const otherTarget = other.points.at(-1)
+    return (
+      (otherSource && target.x === otherSource.x && target.y === otherSource.y) ||
+      (otherTarget && source.x === otherTarget.x && source.y === otherTarget.y)
+    )
+  })
+}
+
+function pathRunsAlongFrame(points: readonly FlowchartPoint[], bounds: FlowchartSubgraphBounds): boolean {
+  const right = bounds.left + bounds.width - 1
+  const bottom = bounds.top + bounds.height - 1
+  for (let index = 1; index < points.length; index++) {
+    const segment = segmentBetween(points[index - 1]!, points[index]!)
+    if (!segment) continue
+    const span = segmentSpan(segment)
+    if (
+      segment.axis === "x" &&
+      (segment.from.y === bounds.top || segment.from.y === bottom) &&
+      Math.min(span.end, right) > Math.max(span.start, bounds.left)
+    ) {
+      return true
+    }
+    if (
+      segment.axis === "y" &&
+      (segment.from.x === bounds.left || segment.from.x === right) &&
+      Math.min(span.end, bottom) > Math.max(span.start, bounds.top)
+    ) {
+      return true
+    }
+  }
+  return false
+}
+
+function subgraphTitleBounds(bounds: FlowchartSubgraphBounds): {
+  left: number
+  top: number
+  width: number
+  height: number
+} {
+  const lines = splitDiagramLines(bounds.label)
+  return {
+    left: bounds.left + 2,
+    top: bounds.labelSide === "top" ? bounds.top : bounds.top + bounds.height - lines.length,
+    width: Math.max(...lines.map((line) => diagramTextWidth(` ${line} `))),
+    height: lines.length,
+  }
+}
+
 function avoidNodeObstacles(
   route: FlowchartEdgeRoute,
   routes: readonly FlowchartEdgeRoute[],
@@ -815,10 +892,23 @@ function avoidNodeObstacles(
       const allowedContact = isSource && isTarget ? "both" : isSource ? "source" : isTarget ? "target" : undefined
       return pathIntersectsBounds(candidate.points, bound, allowedContact)
     })
+  const intersectsStructuralObstacle = (candidate: FlowchartEdgeRoute): boolean =>
+    intersectsNode(candidate) ||
+    allSubgraphBounds.some(
+      (bound) =>
+        pathRunsAlongFrame(candidate.points, bound) ||
+        (bound.label.length > 0 && pathIntersectsBounds(candidate.points, subgraphTitleBounds(bound))),
+    )
+  const intersectsRoutingObstacle = (candidate: FlowchartEdgeRoute): boolean =>
+    intersectsStructuralObstacle(candidate) ||
+    endpointConflictsWithRoutes(candidate, otherRoutes) ||
+    otherRoutes.some(
+      (other) => endpointDisjoint(candidate.edge, other.edge) && pathsIntersect(candidate.points, other.points),
+    )
   const intersectsObstacle = (candidate: FlowchartEdgeRoute): boolean => {
     const label = candidate.edge.label ? flowchartRouteLabelLayout(candidate, diagramTextWidth) : undefined
     return (
-      intersectsNode(candidate) ||
+      intersectsRoutingObstacle(candidate) ||
       allNodeBounds.some((bound) => labelIntersectsBounds(label, bound)) ||
       allSubgraphBounds.some((bound) => labelIntersectsSubgraphFrame(label, bound)) ||
       labelIntersectsLabels(label, otherLabels) ||
@@ -839,19 +929,19 @@ function avoidNodeObstacles(
   const rightBusXs = [
     ...new Set([
       rightBusX,
-      ...otherLabels.map((label) => Math.max(rightBusX, label.point.x + label.width - 1 + BUS_CLEARANCE)),
+      ...otherLabels.map((label) => Math.max(rightBusX, label.point.x + label.width - 1 + NODE_CLEARANCE)),
     ]),
   ].sort((left, right) => left - right)
   const leftBusXs = [
-    ...new Set([leftBusX, ...otherLabels.map((label) => Math.min(leftBusX, label.point.x - BUS_CLEARANCE))]),
+    ...new Set([leftBusX, ...otherLabels.map((label) => Math.min(leftBusX, label.point.x - NODE_CLEARANCE))]),
   ].sort((left, right) => right - left)
   const topBusYs = [
-    ...new Set([topBusY, ...otherLabels.map((label) => Math.min(topBusY, label.point.y - BUS_CLEARANCE))]),
+    ...new Set([topBusY, ...otherLabels.map((label) => Math.min(topBusY, label.point.y - NODE_CLEARANCE))]),
   ].sort((left, right) => right - left)
   const bottomBusYs = [
     ...new Set([
       bottomBusY,
-      ...otherLabels.map((label) => Math.max(bottomBusY, label.point.y + label.height - 1 + BUS_CLEARANCE)),
+      ...otherLabels.map((label) => Math.max(bottomBusY, label.point.y + label.height - 1 + NODE_CLEARANCE)),
     ]),
   ].sort((left, right) => left - right)
   const busLimit = Math.max(1, Math.floor(Math.sqrt(ROUTING_CANDIDATE_BUDGET / 4)))
@@ -953,7 +1043,7 @@ function avoidNodeObstacles(
   if (from.id === to.id)
     return (
       shortest(selfLoops, (candidate) => !intersectsObstacle(candidate)) ??
-      shortest(selfLoops, (candidate) => !intersectsNode(candidate)) ??
+      shortest(selfLoops, (candidate) => !intersectsStructuralObstacle(candidate)) ??
       route
     )
   const currentTargetSide = sideForOutsidePoint(to, route.points.at(-1)!)
@@ -1002,8 +1092,8 @@ function avoidNodeObstacles(
       shortest(sameSides, (candidate) => !intersectsObstacle(candidate)) ??
       shortest(preservedSources, (candidate) => !intersectsObstacle(candidate)) ??
       shortest(attachments, (candidate) => !intersectsObstacle(candidate)) ??
-      shortest(preservedSources, (candidate) => !intersectsNode(candidate)) ??
-      shortest(attachments, (candidate) => !intersectsNode(candidate)) ??
+      shortest(preservedSources, (candidate) => !intersectsStructuralObstacle(candidate)) ??
+      shortest(attachments, (candidate) => !intersectsStructuralObstacle(candidate)) ??
       route
     )
   }
@@ -1012,8 +1102,8 @@ function avoidNodeObstacles(
     shortest(preservedTargets, (candidate) => !intersectsObstacle(candidate)) ??
     attachments.find((candidate) => !intersectsObstacle(candidate)) ??
     shortest(preservedSources, (candidate) => !intersectsObstacle(candidate)) ??
-    shortest(attachments, (candidate) => !intersectsNode(candidate)) ??
-    shortest(preservedSources, (candidate) => !intersectsNode(candidate)) ??
+    shortest(attachments, (candidate) => !intersectsStructuralObstacle(candidate)) ??
+    shortest(preservedSources, (candidate) => !intersectsStructuralObstacle(candidate)) ??
     route
   )
 }
@@ -1023,6 +1113,8 @@ function avoidLabelOverlap(
   otherRoutes: readonly FlowchartEdgeRoute[],
   bounds: ReadonlyMap<string, FlowchartNodeBounds>,
   subgraphBounds: ReadonlyMap<string, FlowchartSubgraphBounds> | undefined,
+  targetWidth?: number,
+  includeLabelWidth = true,
 ): FlowchartEdgeRoute {
   if (!route.edge.label) return route
   const nodeBounds = [...bounds.values()]
@@ -1040,7 +1132,14 @@ function avoidLabelOverlap(
       { left: sourcePoint.x, top: sourcePoint.y, width: 1, height: 1 },
     ]
   })
+  const hasParallelRoute = otherRoutes.some(
+    (other) => other.edge.from === route.edge.from && other.edge.to === route.edge.to,
+  )
   const intersectsObstacle = (label: FlowchartEdgeLabelLayout): boolean =>
+    (targetWidth !== undefined &&
+      (hasParallelRoute || !includeLabelWidth
+        ? label.point.x > targetWidth
+        : label.point.x + label.width > targetWidth)) ||
     nodeBounds.some((bound) => labelIntersectsBounds(label, bound)) ||
     frameBounds.some((bound) => labelIntersectsSubgraphFrame(label, bound)) ||
     labelIntersectsLabels(label, otherLabels) ||
@@ -1094,6 +1193,15 @@ function avoidLabelOverlap(
       }
     }
   }
+  if (targetWidth !== undefined && includeLabelWidth && current.point.x + current.width > targetWidth) {
+    const x = Math.max(0, targetWidth - current.width)
+    for (let distance = 0; distance < 100; distance++) {
+      for (const y of distance === 0 ? [current.point.y] : [current.point.y - distance, current.point.y + distance]) {
+        if (y < 0 || intersectsObstacle({ ...current, point: { x, y } })) continue
+        return { ...route, labelPoint: { x, y } }
+      }
+    }
+  }
   return route
 }
 
@@ -1102,6 +1210,8 @@ export function routeFlowchartEdges(
   bounds: Map<string, FlowchartNodeBounds>,
   directionForEdge: (edge: FlowchartEdge) => FlowchartDirection = () => diagram.direction,
   subgraphBounds?: ReadonlyMap<string, FlowchartSubgraphBounds>,
+  targetWidth?: number,
+  directionAligned = false,
 ): FlowchartEdgeRoute[] {
   const routedDiagram = { ...diagram, edges: diagram.edges.filter((edge) => !edge.orderOnly) }
   const handled = new Set<FlowchartEdge>()
@@ -1110,7 +1220,7 @@ export function routeFlowchartEdges(
     ? Math.min(...[...bounds.values(), ...subgraphBounds.values()].map((bound) => bound.left))
     : undefined
 
-  routeParallelEdges(routedDiagram, bounds, handled, routes)
+  routeParallelEdges(routedDiagram, bounds, directionForEdge, directionAligned, handled, routes)
 
   for (const direction of ["LR", "RL"] satisfies FlowchartDirection[]) {
     const horizontalEdges = routedDiagram.edges.filter(
@@ -1145,11 +1255,109 @@ export function routeFlowchartEdges(
   for (let index = routes.length - 1; index >= 0; index--) {
     routes[index] = avoidNodeObstacles(routes[index]!, routes, bounds, subgraphBounds, index)
   }
+  const subgraphs = diagram.subgraphs ?? []
+  const subgraphById = new Map(subgraphs.map((subgraph) => [subgraph.id, subgraph]))
+  const containers = (id: string) => {
+    const ids = new Set<string>()
+    let current = subgraphs.find((subgraph) => subgraph.nodeIds.includes(id))
+    while (current) {
+      ids.add(current.id)
+      current = current.parentId ? subgraphById.get(current.parentId) : undefined
+    }
+    return ids
+  }
+  const groupedLabelEdge = (edge: FlowchartEdge) => {
+    const fromContainers = containers(edge.from)
+    if (![...containers(edge.to)].some((id) => fromContainers.has(id))) return false
+    const targets = new Set(
+      routedDiagram.edges
+        .filter((candidate) => candidate.label && candidate.from === edge.from)
+        .map((candidate) => candidate.to),
+    )
+    const sources = new Set(
+      routedDiagram.edges
+        .filter((candidate) => candidate.label && candidate.to === edge.to)
+        .map((candidate) => candidate.from),
+    )
+    return targets.size > 1 || sources.size > 1
+  }
   return routes.reduce<FlowchartEdgeRoute[]>((resolved, route, index) => {
-    return [...resolved, avoidLabelOverlap(route, [...resolved, ...routes.slice(index + 1)], bounds, subgraphBounds)]
+    const grouped = groupedLabelEdge(route.edge)
+    return [
+      ...resolved,
+      avoidLabelOverlap(
+        route,
+        [...resolved, ...routes.slice(index + 1)],
+        bounds,
+        subgraphBounds,
+        targetWidth !== undefined && subgraphs.length > 0 && grouped ? Math.max(1, targetWidth - 5) : targetWidth,
+        subgraphs.length === 0 || grouped,
+      ),
+    ]
   }, [])
 }
 
+export function avoidFlowchartFrameBorders(
+  routes: readonly FlowchartEdgeRoute[],
+  bounds: ReadonlyMap<string, FlowchartNodeBounds>,
+  subgraphBounds: ReadonlyMap<string, FlowchartSubgraphBounds>,
+): void {
+  const inside = (node: FlowchartNodeBounds, frame: FlowchartSubgraphBounds) =>
+    node.left >= frame.left &&
+    node.top >= frame.top &&
+    node.left + node.width <= frame.left + frame.width &&
+    node.top + node.height <= frame.top + frame.height
+
+  for (const route of routes) {
+    const source = bounds.get(route.edge.from)
+    const target = bounds.get(route.edge.to)
+    for (const frame of subgraphBounds.values()) {
+      const inward = Boolean(source && target && inside(source, frame) && inside(target, frame))
+      const right = frame.left + frame.width - 1
+      const bottom = frame.top + frame.height - 1
+      const points: FlowchartPoint[] = [route.points[0]!]
+      for (let index = 1; index < route.points.length; index++) {
+        const from = route.points[index - 1]!
+        const to = route.points[index]!
+        const segment = segmentBetween(from, to)
+        if (!segment) continue
+        const span = segmentSpan(segment)
+        const horizontalSide =
+          segment.axis === "x" && Math.min(span.end, right) > Math.max(span.start, frame.left)
+            ? segment.from.y === frame.top
+              ? "top"
+              : segment.from.y === bottom
+                ? "bottom"
+                : undefined
+            : undefined
+        const verticalSide =
+          segment.axis === "y" && Math.min(span.end, bottom) > Math.max(span.start, frame.top)
+            ? segment.from.x === frame.left
+              ? "left"
+              : segment.from.x === right
+                ? "right"
+                : undefined
+            : undefined
+        if (!horizontalSide && !verticalSide) {
+          points.push(to)
+          continue
+        }
+
+        const offset = horizontalSide
+          ? horizontalSide === "top"
+            ? frame.top + (inward ? 1 : -1)
+            : bottom + (inward ? -1 : 1)
+          : verticalSide === "left"
+            ? frame.left + (inward ? 1 : -1)
+            : right + (inward ? -1 : 1)
+        if (horizontalSide) points.push({ x: from.x, y: offset }, { x: to.x, y: offset }, to)
+        else points.push({ x: offset, y: from.y }, { x: offset, y: to.y }, to)
+      }
+      route.points = pathThrough(points)
+    }
+  }
+}
+
 function sideForOutsidePoint(bounds: FlowchartNodeBounds, sourcePoint: FlowchartPoint): DiagramSide {
   if (sourcePoint.x < bounds.left) return "left"
   if (sourcePoint.x >= bounds.left + bounds.width) return "right"

packages/merman/src/flowchart/style.ts

@@ -10,7 +10,7 @@ import {
   type DiagramRgb,
 } from "../core/color/style.js"
 
-export type FlowchartBaseCellStyle = "node" | "database" | "edge" | "label" | "group"
+export type FlowchartBaseCellStyle = "node" | "nodeBorder" | "database" | "databaseBorder" | "edge" | "label" | "group"
 export type FlowchartNodeEdgeFadeStyle = `nodeEdgeFade${DiagramFadeStep}`
 export type FlowchartDatabaseEdgeFadeStyle = `databaseEdgeFade${DiagramFadeStep}`
 export type FlowchartEdgeFadeStyle = FlowchartNodeEdgeFadeStyle | FlowchartDatabaseEdgeFadeStyle
@@ -22,7 +22,9 @@ export type FlowchartGrid = DiagramCanvas<FlowchartCellStyle, FlowchartCellMetad
 export type FlowchartStyleColors = Required<Record<FlowchartCellStyle, RGBA>>
 export const DEFAULT_THEME_RGB = {
   node: [228, 239, 232],
+  nodeBorder: [141, 163, 151],
   database: [228, 239, 232],
+  databaseBorder: [141, 163, 151],
   edge: [134, 225, 200],
   label: [134, 225, 200],
   group: [76, 99, 89],
@@ -35,16 +37,20 @@ export function resolveFlowchartStyleColors(
   colors: Partial<Record<FlowchartCellStyle, RGBA | undefined>> = {},
 ): FlowchartStyleColors {
   const node = colors.node ?? rgba(DEFAULT_THEME_RGB.node)
+  const nodeBorder = colors.nodeBorder ?? rgba(DEFAULT_THEME_RGB.nodeBorder)
   const database = colors.database ?? rgba(DEFAULT_THEME_RGB.database)
+  const databaseBorder = colors.databaseBorder ?? rgba(DEFAULT_THEME_RGB.databaseBorder)
   const edge = colors.edge ?? rgba(DEFAULT_THEME_RGB.edge)
   return {
     node,
+    nodeBorder,
     database,
+    databaseBorder,
     edge,
     label: colors.label ?? rgba(DEFAULT_THEME_RGB.label),
     group: colors.group ?? rgba(DEFAULT_THEME_RGB.group),
-    ...createColorRampTheme(NODE_EDGE_FADE_STYLES, node, edge),
-    ...createColorRampTheme(DATABASE_EDGE_FADE_STYLES, database, edge),
+    ...createColorRampTheme(NODE_EDGE_FADE_STYLES, nodeBorder, edge),
+    ...createColorRampTheme(DATABASE_EDGE_FADE_STYLES, databaseBorder, edge),
   }
 }
 

packages/merman/src/layout-audit.test.ts

@@ -0,0 +1,81 @@
+import { expect, test } from "bun:test"
+import { auditAllFixtures, auditFixture, summarizeAudits, worstAudits } from "./test/layout-audit/harness.js"
+import { layoutFixtures } from "./test/layout-audit/fixtures.js"
+
+test("audits deterministic flowchart and state layout families", () => {
+  const fixtures = layoutFixtures()
+  const flowcharts = fixtures.filter((fixture) => fixture.kind === "flowchart")
+  const states = fixtures.filter((fixture) => fixture.kind === "state")
+  expect(flowcharts.length).toBeGreaterThanOrEqual(100)
+  expect(states.length).toBeGreaterThanOrEqual(100)
+  expect(new Set(fixtures.map((fixture) => fixture.id)).size).toBe(fixtures.length)
+
+  const startedAt = performance.now()
+  const audits = auditAllFixtures()
+  const elapsedMs = performance.now() - startedAt
+  const violations = audits.flatMap((audit) =>
+    audit.violations.map((violation) => `${audit.fixture.id} @${audit.viewport}: ${violation}`),
+  )
+  const summary = summarizeAudits(audits)
+
+  expect(audits.length).toBeGreaterThanOrEqual(fixtures.length)
+  expect(violations).toEqual([])
+  expect(elapsedMs).toBeLessThan(35_000)
+  for (const audit of audits.filter((audit) => audit.fixture.kind === "state")) {
+    expect(audit.viewport).toBe(audit.fixture.profile === "short" ? 60 : audit.fixture.profile === "unicode" ? 80 : 120)
+  }
+  for (const id of ["state/chain/lr-long", "state/chain/rl-long"]) {
+    const audit = audits.find((candidate) => candidate.fixture.id === id)!
+    expect(audit.viewport).toBe(120)
+    expect([audit.metrics.width, audit.metrics.height, audit.metrics.overflow]).toEqual([84, 41, 0])
+  }
+  expect(
+    audits
+      .filter((audit) => audit.fixture.id === "flowchart/deployment-architecture/curated")
+      .map((audit) => audit.viewport),
+  ).toEqual([60, 80, 120])
+  expect(summary.total.area.max).toBeLessThanOrEqual(11_011)
+  expect(summary.total.area.p95).toBeLessThanOrEqual(5_313)
+  expect(summary.total.bends.max).toBeLessThanOrEqual(30)
+  expect(summary.total.bends.p95).toBeLessThanOrEqual(11)
+  expect(summary.total.crossings.total).toBeLessThanOrEqual(40)
+  expect(summary.total.crossings.max).toBeLessThanOrEqual(3)
+  expect(summary.total.routeLength.max).toBeLessThanOrEqual(930)
+  expect(summary.total.routeLength.p95).toBeLessThanOrEqual(364)
+  expect(summary.total.sharedRouteCells.max).toBeLessThanOrEqual(547)
+  expect(summary.total.sharedRouteCells.p95).toBeLessThanOrEqual(122)
+  expect(summary.total.overflow.max).toBeLessThanOrEqual(170)
+  expect(summary.total.overflow.p95).toBeLessThanOrEqual(99)
+  expect(summary.state.crossings.total).toBe(0)
+
+  for (const fixture of [...Map.groupBy(fixtures, (candidate) => `${candidate.kind}/${candidate.family}`).values()].map(
+    (family) => family[0]!,
+  )) {
+    const first = auditFixture(fixture, 80)
+    const second = auditFixture(fixture, 80)
+    expect(second.output).toBe(first.output)
+    expect(second.metrics).toEqual(first.metrics)
+    expect(second.violations).toEqual(first.violations)
+  }
+
+  console.log(
+    `[layout-audit] ${fixtures.length} sources, ${audits.length} runs, ${elapsedMs.toFixed(0)}ms`,
+    JSON.stringify({
+      summary,
+      worst: {
+        area: worstAudits(audits, "area", 3).map((audit) => [audit.fixture.id, audit.viewport, audit.metrics.area]),
+        bends: worstAudits(audits, "bends", 3).map((audit) => [audit.fixture.id, audit.viewport, audit.metrics.bends]),
+        crossings: worstAudits(audits, "crossings", 3).map((audit) => [
+          audit.fixture.id,
+          audit.viewport,
+          audit.metrics.crossings,
+        ]),
+        overflow: worstAudits(audits, "overflow", 3).map((audit) => [
+          audit.fixture.id,
+          audit.viewport,
+          audit.metrics.overflow,
+        ]),
+      },
+    }),
+  )
+}, 40_000)

packages/merman/src/markdown.ts

@@ -51,7 +51,7 @@ interface PreparedDiagram {
 export interface MermaidMarkdownRendererOptions {
   /** Use terminal-optimized diagram spacing. Defaults to true. */
   compact?: boolean
-  /** Fold horizontal flowcharts that exceed this width. Defaults to 120 columns. */
+  /** Fold responsive horizontal diagrams that exceed this width. Defaults to 120 columns. */
   layoutMaxWidth?: number
   /** Gantt-specific terminal rendering options. */
   gantt?: Omit<GanttDiagramRenderOptions, "layoutMaxWidth">
@@ -141,7 +141,9 @@ function prepareDiagram(
           grid,
           resolveFlowchartStyleColors({
             node: color(colors.primary),
+            nodeBorder: color(colors.muted),
             database: color(colors.primary),
+            databaseBorder: color(colors.muted),
             edge: color(colors.secondary),
             label: color(colors.text),
             group: color(colors.muted),
@@ -215,8 +217,8 @@ function prepareDiagram(
       }
     }
     case "state": {
-      const grid = drawStateDiagramGrid(parseMermaidStateDiagram(source))
-      const size = grid.getTextSize({ trimBottom: true })
+      const grid = drawStateDiagramGrid(parseMermaidStateDiagram(source), { layoutMaxWidth })
+      const size = grid.getTextSize({ trimTop: true, trimBottom: true })
       return {
         kind,
         source,

packages/merman/src/state/diagram.test.ts

@@ -3,7 +3,7 @@ import stringWidth from "string-width"
 import { spatialPathClaim } from "../core/spatial.js"
 import { expectDiagram } from "../test/diagram.js"
 import { renderStateDiagram } from "./diagram.js"
-import { drawStateDiagramGrid } from "./drawing.js"
+import { createStateDiagramDrawing, drawStateDiagramGrid } from "./drawing.js"
 import { createStateDiagramLayout } from "./layout.js"
 import { parseMermaidStateDiagram } from "./parser.js"
 import { prepareVisibleStateDiagram } from "./visible-model.js"
@@ -60,6 +60,35 @@ function expectCompleteStateDiagram(source: string, output = renderStateDiagram(
   }
 }
 
+type ResponsiveStateLabelProfile = "short" | "long" | "unicode"
+
+function responsiveStateChain(direction: "LR" | "RL", profile: ResponsiveStateLabelProfile): string {
+  const stateLabel = (id: string) => {
+    if (profile === "long") return `${id} deliberate state with a long descriptive label`
+    if (profile === "unicode") return `${id} 東京<br/>résumé 🚀`
+    return `${id} node`
+  }
+  const transitionLabel = (id: string) => {
+    if (profile === "long") return `${id} transition carrying detailed context`
+    if (profile === "unicode") return `${id} 東京<br/>✓ prêt`
+    return `${id} edge`
+  }
+  const ids = ["A", "B", "C", "D", "E"]
+  return [
+    "stateDiagram-v2",
+    `direction ${direction}`,
+    ...ids.map((id) => `state "${stateLabel(id)}" as ${id}`),
+    "[*] --> A",
+    ...ids.slice(0, -1).map((id, index) => `${id} --> ${ids[index + 1]}: ${transitionLabel(`E0${index + 1}`)}`),
+    "E --> [*]",
+  ].join("\n")
+}
+
+function renderedStateDimensions(output: string) {
+  const lines = output.split("\n")
+  return { width: Math.max(...lines.map((line) => stringWidth(line))), height: lines.length }
+}
+
 describe("StateDiagram", () => {
   test("detects and parses Mermaid state diagrams", () => {
     const diagram = parseMermaidStateDiagram(`
@@ -179,6 +208,95 @@ stateDiagram-v2
     expect(output).toContain("◀")
   })
 
+  test("renders reverse vertical direction from bottom to top", () => {
+    const source = `stateDiagram-v2
+  direction BT
+  A --> B`
+    const drawing = createStateDiagramDrawing(parseMermaidStateDiagram(source))
+
+    expect(drawing.layout.bounds.get("A")!.top).toBeGreaterThan(drawing.layout.bounds.get("B")!.top)
+    expect(drawing.grid.toString({ trimTop: true, trimBottom: true })).toContain("▲")
+  })
+
+  test.each(
+    (["LR", "RL"] as const).flatMap((direction) =>
+      (["short", "long", "unicode"] as const).flatMap((profile) =>
+        ([60, 80, 120] as const).map((layoutMaxWidth) => [direction, profile, layoutMaxWidth] as const),
+      ),
+    ),
+  )("folds responsive %s %s chains at %d columns", (direction, profile, layoutMaxWidth) => {
+    const source = responsiveStateChain(direction, profile)
+    const horizontal = renderStateDiagram(source)
+    const responsive = renderStateDiagram(source, { layoutMaxWidth })
+    const vertical = renderStateDiagram(source, { direction: direction === "RL" ? "BT" : "TB" })
+
+    expect(renderedStateDimensions(horizontal).width).toBeGreaterThan(layoutMaxWidth)
+    expect(responsive).toBe(vertical)
+    expect(renderedStateDimensions(responsive).width).toBeLessThan(renderedStateDimensions(horizontal).width)
+    for (const content of ["A", "B", "C", "D", "E", "E01", "E02", "E03", "E04"]) {
+      expect(responsive).toContain(content)
+    }
+  })
+
+  test.each(["LR", "RL"] as const)("keeps the narrower %s orientation for broad ranks", (direction) => {
+    const source = `stateDiagram-v2
+  direction ${direction}
+${Array.from({ length: 8 }, (_, index) => `  A --> B${index}`).join("\n")}`
+    const horizontal = renderStateDiagram(source)
+    const vertical = renderStateDiagram(source, { direction: direction === "RL" ? "BT" : "TB" })
+    const responsive = renderStateDiagram(source, { layoutMaxWidth: 60 })
+
+    expect(renderedStateDimensions(horizontal).width).toBeLessThan(renderedStateDimensions(vertical).width)
+    expect(responsive).toBe(horizontal)
+  })
+
+  test("falls back before allocating an oversized horizontal canvas", () => {
+    const ids = Array.from({ length: 301 }, (_, index) => `S${index}`)
+    const label = "transition label carrying enough context to make the horizontal canvas too large"
+    const source = `stateDiagram-v2
+  direction LR
+${ids
+  .slice(0, -1)
+  .map((id, index) => `  ${id} --> ${ids[index + 1]}: ${label}`)
+  .join("\n")}`
+    const output = renderStateDiagram(source, { layoutMaxWidth: 80 })
+
+    expect(output).toContain("S0")
+    expect(output).toContain("S300")
+    expect(renderedStateDimensions(output).width).toBeLessThanOrEqual(stringWidth(label) + 8)
+  })
+
+  test.each(["TB", "TD", "BT"] as const)("preserves explicit %s layouts under a narrow width target", (direction) => {
+    const source = `stateDiagram-v2
+  direction ${direction}
+  A --> B: next`
+
+    expect(renderStateDiagram(source, { layoutMaxWidth: 1 })).toBe(renderStateDiagram(source))
+  })
+
+  test("preserves horizontal layouts that fit or have no finite width target", () => {
+    const source = `stateDiagram-v2
+  direction LR
+  A --> B`
+    const output = renderStateDiagram(source)
+
+    expect(renderStateDiagram(source, { layoutMaxWidth: 120 })).toBe(output)
+    expect(renderStateDiagram(source, { layoutMaxWidth: Number.POSITIVE_INFINITY })).toBe(output)
+  })
+
+  test("treats a single irreducibly wide state as soft overflow", () => {
+    const label = "界".repeat(40)
+    const output = renderStateDiagram(
+      `stateDiagram-v2
+  direction LR
+  state "${label}" as Wide`,
+      { layoutMaxWidth: 60 },
+    )
+
+    expect(renderedStateDimensions(output).width).toBeGreaterThan(60)
+    expect(output).toContain(label)
+  })
+
   test("does not mutate a parsed diagram when rendering with a direction override", () => {
     const diagram = parseMermaidStateDiagram(`stateDiagram-v2
   direction LR
@@ -249,24 +367,21 @@ stateDiagram-v2
 
     for (const line of labelLines) expect(output.split(line)).toHaveLength(2)
     expect(output).toMatchInlineSnapshot(`
-      "
-        create from base image ╭─────────╮
+      "  create from base image ╭─────────╮
       ●───────────────────────▶│ Running │
-                               ╰──┬──────╯ 💥 sandbox dies BEFORE hook fires
-                                ▲ │   ▲    (crash, our bug, race)
-                       ╭────────┼─┴───┼───────╮
+                               ╰──┬──────╯
+                                ▲ │   ▲        💥 sandbox dies BEFORE hook fires
+                       ╭────────┼─┴───┼───────╮(crash, our bug, race)
                        ▼   ╭────┼─────╯       ▼
                     ╭──────┴──╮ │           ╭──────╮
                     │ Dormant │ │           │ Lost │
                     ╰─────────╯ │           ╰───┬──╯
                                 │               │
-       📸 suspend hook fires    │               │
-       (WE must call it on idle)│               │
+       📸 suspend hook fires    │               │ wake from LAST snapshot
+       (WE must call it on idle)│               │ ⚠ files since then GONE
                                 ╰───────────────╯
                             wake from snapshot image
-                            (apt installs restored!)
-                                  wake from LAST snapshot
-                                  ⚠ files since then GONE"
+                            (apt installs restored!)"
     `)
   })
 
@@ -505,6 +620,14 @@ stateDiagram-v2
     expect(output.split("\n").filter((line) => line.trim())).toHaveLength(3)
   })
 
+  test.each(["LR", "RL"] as const)("trims leading rows from standalone %s choices", (direction) => {
+    const output = renderStateDiagram(`stateDiagram-v2
+  direction ${direction}
+  state Decision <<choice>>`)
+
+    expect(output).toBe("◆")
+  })
+
   test("renders parallel transitions without losing labels", () => {
     const horizontal = renderStateDiagram(`stateDiagram-v2
   direction LR
@@ -683,6 +806,135 @@ stateDiagram-v2
     }
   })
 
+  test("grows parallel vertical diagrams by the maximum label width rather than their sum", () => {
+    const render = (labels: readonly string[]) =>
+      renderStateDiagram(`stateDiagram-v2
+  direction TB
+${labels.map((label) => `  A --> B: ${label}`).join("\n")}`)
+    const shortLabels = ["one", "two", "three"]
+    const longLabels = [
+      "alpha route label that is deliberately long",
+      "beta route label that is deliberately long",
+      "gamma route label that is deliberately long",
+    ]
+    const width = (output: string) => Math.max(...output.split("\n").map((line) => stringWidth(line)))
+    const labelGrowth =
+      Math.max(...longLabels.map((label) => stringWidth(label))) -
+      Math.max(...shortLabels.map((label) => stringWidth(label)))
+
+    expect(width(render(longLabels)) - width(render(shortLabels))).toBeLessThanOrEqual(labelGrowth + 2)
+  })
+
+  test("keeps audited parallel labels clear of frames and rails", () => {
+    const output = renderStateDiagram(`stateDiagram-v2
+  direction TB
+  A --> B: alpha route label that is deliberately long
+  A --> B: beta route label that is deliberately long
+  A --> B: gamma route label that is deliberately long`)
+
+    expect(output).toMatchInlineSnapshot(`
+      "╭───╮ alpha route label that is deliberately long
+      │ A ├───┬──╮
+      ╰─┬─╯   │  │
+        │     │  │ gamma route label that is deliberately long
+        │     │  │ beta route label that is deliberately long
+        │     │  │
+        ▼     │  │
+      ╭───╮   │  │
+      │ B │◀──┴──╯
+      ╰───╯"
+    `)
+  })
+
+  test("keeps audited repeated self-transition lanes distinct and readable", () => {
+    const output = renderStateDiagram(`stateDiagram-v2
+  direction LR
+  A --> A: one
+  A --> A: two
+  A --> A: three`)
+
+    expect(output).toMatchInlineSnapshot(`
+      "╭───╮
+      │ A │
+      ╰─┬─╯
+        │  ▲   ▲   ▲
+        ├──╯   │   │
+        │      │   │
+        │ one  │   │
+        ├──────╯   │
+        │          │
+        │     two  │ three
+        ╰──────────╯"
+    `)
+  })
+
+  test("expands composites around self-transition labels without engulfing external states", () => {
+    const source = `stateDiagram-v2
+  direction LR
+  state Outer {
+    A --> A: loop-0
+    A --> A: loop-1
+    A --> A: loop-2
+  }
+  A --> C`
+    const drawing = createStateDiagramDrawing(parseMermaidStateDiagram(source))
+    const outer = drawing.layout.compositeBounds.get("Outer")!
+    const external = drawing.layout.bounds.get("C")!
+    const output = drawing.grid.toString({ trimTop: true, trimBottom: true })
+
+    expect(
+      external.left < outer.left + outer.width &&
+        external.left + external.width > outer.left &&
+        external.top < outer.top + outer.height &&
+        external.top + external.height > outer.top,
+    ).toBe(false)
+    for (const plan of drawing.transitionPlans.filter(
+      (plan) => plan.route.transition.from === plan.route.transition.to,
+    )) {
+      expect(plan.label).toBeDefined()
+      expect(plan.label!.x).toBeGreaterThan(outer.left)
+      expect(plan.label!.y).toBeGreaterThan(outer.top)
+      expect(plan.label!.x + Math.max(...plan.label!.lines.map((line) => stringWidth(line)))).toBeLessThan(
+        outer.left + outer.width,
+      )
+      expect(plan.label!.y + plan.label!.lines.length).toBeLessThan(outer.top + outer.height)
+    }
+    for (const label of ["loop-0", "loop-1", "loop-2"]) expect(output.match(new RegExp(label, "g"))).toHaveLength(1)
+  })
+
+  test("keeps audited nested note connectors direct and inside every frame", () => {
+    const output = renderStateDiagram(`stateDiagram-v2
+  direction TB
+  state Outer {
+    state Inner {
+      A --> B: down
+      B --> A: up
+      note right of B: note
+    }
+  }`)
+
+    expect(output).toMatchInlineSnapshot(`
+      "╭─ Outer ───────────────╮
+      │                       │
+      │ ╭─ Inner ───────────╮ │
+      │ │                   │ │
+      │ │ ╭───╮             │ │
+      │ │▶│ A │             │ │
+      │ ││╰─┬─╯             │ │
+      │ ││  │               │ │
+      │ ││  │ down          │ │
+      │ ││  │               │ │
+      │ ││  ▼               │ │
+      │ ││╭───╮    ╔══════╗ │ │
+      │ │╰┤ B │════╣ note ║ │ │
+      │ │ ╰───╯    ╚══════╝ │ │
+      │ │up                 │ │
+      │ ╰───────────────────╯ │
+      │                       │
+      ╰───────────────────────╯"
+    `)
+  })
+
   test("keeps explicit choices visible in choice-only cycles", () => {
     const output = renderStateDiagram(`stateDiagram-v2
   direction TB

packages/merman/src/state/drawing.ts

@@ -1,5 +1,5 @@
 import { BorderChars, type BorderCharacters, type BorderStyle } from "@opentui/core"
-import { DiagramCanvas, type DiagramCanvasCell } from "../core/canvas.js"
+import { DiagramCanvas, DiagramCanvasSizeError, type DiagramCanvasCell } from "../core/canvas.js"
 import { directionBetween, orthogonalPathPoints, type DiagramDirection } from "../core/geometry.js"
 import {
   diagramArrowHead,
@@ -12,6 +12,7 @@ import {
   createStateDiagramLayout,
   expandCompositeBoundsForFeedback,
   expandCompositeBoundsForInternalTransitions,
+  separateExternalBoundsFromComposites,
   translateStateDiagramLayout,
   type StateDiagramBoxBounds as BoxBounds,
   type StateDiagramNoteBounds as StateNoteBounds,
@@ -67,23 +68,11 @@ function makeGrid(width: number, height: number): StateGrid {
   })
 }
 
-function setCell(
-  grid: StateGrid,
-  x: number,
-  y: number,
-  char: string,
-  style?: StateCellStyle,
-): void {
+function setCell(grid: StateGrid, x: number, y: number, char: string, style?: StateCellStyle): void {
   grid.setCell(x, y, char, style)
 }
 
-function setText(
-  grid: StateGrid,
-  x: number,
-  y: number,
-  text: string,
-  style?: StateCellStyle,
-): void {
+function setText(grid: StateGrid, x: number, y: number, text: string, style?: StateCellStyle): void {
   grid.setText(x, y, text, style)
 }
 
@@ -108,12 +97,7 @@ function drawBox(
   })
 }
 
-function drawStateFrame(
-  grid: StateGrid,
-  bounds: BoxBounds,
-  chars: BorderCharacters,
-  style: StateCellStyle,
-): void {
+function drawStateFrame(grid: StateGrid, bounds: BoxBounds, chars: BorderCharacters, style: StateCellStyle): void {
   drawDiagramFrame(bounds, chars, (x, y, char) => setCell(grid, x, y, char, style))
 }
 
@@ -125,6 +109,10 @@ function drawContainerFrame(
   style: StateCellStyle,
 ): void {
   drawDiagramFrame(bounds, chars, (x, y, char) => setCell(grid, x, y, char, style))
+  drawContainerLabel(grid, bounds, label, style)
+}
+
+function drawContainerLabel(grid: StateGrid, bounds: BoxBounds, label: string, style: StateCellStyle): void {
   if (label) setText(grid, bounds.left + 2, bounds.top, ` ${label} `, style)
 }
 
@@ -190,9 +178,7 @@ function drawTransitionRenderPlan(
     setCell(grid, cell.x, cell.y, char, departure.get(`${cell.x}:${cell.y}`) ?? "transition")
   }
   if (plan.label) {
-    plan.label.lines.forEach((line, index) =>
-      setText(grid, plan.label!.x, plan.label!.y + index, line, "label"),
-    )
+    plan.label.lines.forEach((line, index) => setText(grid, plan.label!.x, plan.label!.y + index, line, "label"))
   }
 }
 
@@ -210,8 +196,49 @@ function drawTransitionJunctionPlans(
 }
 
 export function drawStateDiagramGrid(sourceDiagram: StateDiagram, options: StateDiagramRenderOptions = {}): StateGrid {
-  const directedDiagram = options.direction ? { ...sourceDiagram, direction: options.direction } : sourceDiagram
-  const diagram = prepareVisibleStateDiagram(directedDiagram)
+  return createStateDiagramDrawing(sourceDiagram, options).grid
+}
+
+export function createStateDiagramDrawing(sourceDiagram: StateDiagram, options: StateDiagramRenderOptions = {}) {
+  const direction = options.direction ?? sourceDiagram.direction
+  if (direction !== "LR" && direction !== "RL") {
+    return createStateDiagramDrawingWithDirection(sourceDiagram, options, direction)
+  }
+  if (options.layoutMaxWidth === undefined || !Number.isFinite(options.layoutMaxWidth)) {
+    return createStateDiagramDrawingWithDirection(sourceDiagram, options, direction)
+  }
+  const fallbackDirection = direction === "RL" ? "BT" : "TB"
+  const maxWidth = Math.max(1, Math.trunc(options.layoutMaxWidth))
+  const drawing = (() => {
+    try {
+      return createStateDiagramDrawingWithDirection(sourceDiagram, options, direction)
+    } catch (error) {
+      if (error instanceof DiagramCanvasSizeError) return undefined
+      throw error
+    }
+  })()
+  if (!drawing) return createStateDiagramDrawingWithDirection(sourceDiagram, options, fallbackDirection)
+  if (drawing.grid.getTextSize({ trimTop: true, trimBottom: true }).width <= maxWidth) {
+    return drawing
+  }
+  const fallback = createStateDiagramDrawingWithDirection(sourceDiagram, options, fallbackDirection)
+  if (
+    fallback.grid.getTextSize({ trimTop: true, trimBottom: true }).width >=
+    drawing.grid.getTextSize({ trimTop: true, trimBottom: true }).width
+  ) {
+    return drawing
+  }
+  return fallback
+}
+
+function createStateDiagramDrawingWithDirection(
+  sourceDiagram: StateDiagram,
+  options: StateDiagramRenderOptions,
+  direction: StateDiagram["direction"],
+) {
+  const diagram = prepareVisibleStateDiagram(
+    direction === sourceDiagram.direction ? sourceDiagram : { ...sourceDiagram, direction },
+  )
   const borderStyle = options.borderStyle ?? DEFAULT_STATE_BORDER_STYLE
   const arrowHeadStyle = options.arrowHeadStyle ?? DEFAULT_STATE_ARROW_HEAD_STYLE
   const minStateGap = normalizeStateMinStateGap(options.minStateGap)
@@ -226,21 +253,24 @@ export function drawStateDiagramGrid(sourceDiagram: StateDiagram, options: State
   const feedbackLaneY = maxY + 3
   const feedbackTopY = Math.min(0, ...allBounds.map((bound) => bound.top)) - 3
   expandCompositeBoundsForFeedback(diagram, bounds, compositeBounds, feedbackLaneY)
-  let transitionPlans = createStateTransitionRenderPlans(diagram, bounds, feedbackLaneY, {
-    feedbackTopY,
-    noteBounds,
-    searchBudget,
-  })
-  expandCompositeBoundsForInternalTransitions(diagram, compositeBounds, transitionPlans)
+  let transitionPlans: StateTransitionRenderPlan[] = []
+  const separationAttempts = diagram.states.length + diagram.composites.length + 1
+  for (let attempt = 0; attempt < separationAttempts; attempt++) {
+    transitionPlans = createStateTransitionRenderPlans(diagram, bounds, feedbackLaneY, {
+      feedbackTopY,
+      noteBounds,
+      searchBudget,
+    })
+    expandCompositeBoundsForInternalTransitions(diagram, compositeBounds, transitionPlans)
+    if (!separateExternalBoundsFromComposites(diagram, layout)) break
+    if (attempt === separationAttempts - 1) throw new Error("State composite separation did not converge")
+  }
   const connectorPoints = noteBounds.flatMap((bound) => bound.connector?.points ?? [])
   const contentLeft = Math.min(
     0,
     ...[...bounds.values(), ...noteBounds].map((bound) => bound.left),
     ...connectorPoints.map((point) => point.x),
-    ...transitionPlans.flatMap((plan) => [
-      ...plan.cells.map((cell) => cell.x),
-      ...(plan.label ? [plan.label.x] : []),
-    ]),
+    ...transitionPlans.flatMap((plan) => [...plan.cells.map((cell) => cell.x), ...(plan.label ? [plan.label.x] : [])]),
   )
   const contentTop = Math.min(
     0,
@@ -305,10 +335,15 @@ export function drawStateDiagramGrid(sourceDiagram: StateDiagram, options: State
 
   drawTransitionJunctionPlans(grid, diagram, bounds, transitionPlans)
 
+  for (const composite of diagram.composites) {
+    const bound = compositeBounds.get(composite.id)
+    if (bound) drawContainerLabel(grid, bound, composite.label, "composite")
+  }
+
   for (const noteBound of noteBounds) {
     const target = bounds.get(noteBound.note.target)
     if (target) drawNote(grid, noteBound, target)
   }
 
-  return grid
+  return { grid, diagram, layout, transitionPlans }
 }

packages/merman/src/state/layout.test.ts

@@ -2,7 +2,7 @@ import { describe, expect, test } from "bun:test"
 import { spatialPathClaim } from "../core/spatial.js"
 import { diagramTextWidth } from "../core/text.js"
 import type { StateDiagram } from "./types.js"
-import { createStateDiagramLayout } from "./layout.js"
+import { createStateDiagramLayout, expandCompositeBoundsForInternalTransitions } from "./layout.js"
 import { stateDiagramNoteConnector } from "./note.js"
 import { parseMermaidStateDiagram } from "./parser.js"
 import { createStateTransitionRenderPlans } from "./routing.js"
@@ -192,4 +192,75 @@ describe("StateDiagramLayout", () => {
     )
     expect(plans.every((plan) => plan.path.every(([x, y]) => !noteCells.has(`${x}:${y}`)))).toBe(true)
   })
+
+  test.each([
+    ["LR", -1],
+    ["RL", 1],
+  ] as const)("keeps a reciprocal pair on the %s axis", (direction, expectedSign) => {
+    const diagram = prepareVisibleStateDiagram(
+      parseMermaidStateDiagram(`stateDiagram-v2
+  direction ${direction}
+  A --> B: forward
+  B --> A: backward`),
+    )
+    const layout = createStateDiagramLayout(diagram, { minStateGap: 5 })
+    const a = layout.bounds.get("A")!
+    const b = layout.bounds.get("B")!
+
+    expect(a.centerY).toBe(b.centerY)
+    expect(Math.sign(a.centerX - b.centerX)).toBe(expectedSign)
+  })
+
+  test.each(["TB", "TD"] as const)(
+    "contains nested internal feedback with strict margins in %s diagrams",
+    (direction) => {
+      const diagram = prepareVisibleStateDiagram(
+        parseMermaidStateDiagram(`stateDiagram-v2
+  direction ${direction}
+  state Outer {
+    state Inner {
+      A --> B: down
+      B --> A: up
+      note right of B: nested note
+    }
+  }`),
+      )
+      const layout = createStateDiagramLayout(diagram, { minStateGap: 5 })
+      const plans = createStateTransitionRenderPlans(diagram, layout.bounds, 30, { noteBounds: layout.noteBounds })
+      expandCompositeBoundsForInternalTransitions(diagram, layout.compositeBounds, plans)
+      const inner = layout.compositeBounds.get("Inner")!
+      const outer = layout.compositeBounds.get("Outer")!
+      const note = layout.noteBounds[0]!
+
+      for (const composite of [inner, outer]) {
+        for (const plan of plans) {
+          expect(
+            plan.path.every(
+              ([x, y]) =>
+                x > composite.left &&
+                x < composite.left + composite.width - 1 &&
+                y > composite.top &&
+                y < composite.top + composite.height - 1,
+            ),
+          ).toBe(true)
+        }
+        expect(
+          note.connector!.points.every(
+            (point) =>
+              point.x > composite.left &&
+              point.x < composite.left + composite.width - 1 &&
+              point.y > composite.top &&
+              point.y < composite.top + composite.height - 1,
+          ),
+        ).toBe(true)
+      }
+      expect(new Set(note.connector!.points.map((point) => point.y))).toEqual(
+        new Set([layout.bounds.get("B")!.centerY]),
+      )
+      expect(inner.left - outer.left).toBeGreaterThanOrEqual(2)
+      expect(inner.top - outer.top).toBeGreaterThanOrEqual(2)
+      expect(outer.left + outer.width - (inner.left + inner.width)).toBeGreaterThanOrEqual(2)
+      expect(outer.top + outer.height - (inner.top + inner.height)).toBeGreaterThanOrEqual(2)
+    },
+  )
 })

packages/merman/src/state/layout.ts

@@ -131,7 +131,8 @@ function computeMainPath(diagram: StateDiagram): string[] {
         const fromParent = statesById.get(current)?.parentId
         const toParent = statesById.get(transition.to)?.parentId
         return Boolean(fromParent && toParent && fromParent !== toParent)
-      })
+      }) ??
+      (path.length === 1 && candidates.length === 1 ? candidates[0] : undefined)
     if (!next) break
     path.push(next.to)
     visited.add(next.to)
@@ -319,7 +320,12 @@ function findNoteConnector(
   const isFree = (point: DiagramPoint): boolean =>
     point.x >= 0 &&
     !search.blocked.has(`${point.x}:${point.y}`) &&
-    !(point.x >= bounds.left && point.x < bounds.left + bounds.width && point.y >= bounds.top && point.y < bounds.top + bounds.height)
+    !(
+      point.x >= bounds.left &&
+      point.x < bounds.left + bounds.width &&
+      point.y >= bounds.top &&
+      point.y < bounds.top + bounds.height
+    )
   if (!isFree(end) || !isFree(goal)) return undefined
 
   for (const start of starts.filter(isFree)) {
@@ -335,14 +341,7 @@ function findNoteConnector(
   const minY = Math.min(target.top, bounds.top, search.minY) - margin
   const maxX = Math.max(target.left + target.width, bounds.left + bounds.width, search.maxX) + margin
   const maxY = Math.max(target.top + target.height, bounds.top + bounds.height, search.maxY) + margin
-  const path = findStateManhattanPath(
-    starts,
-    goal,
-    search,
-    { minX: 0, minY, maxX, maxY },
-    budget,
-    isFree,
-  )
+  const path = findStateManhattanPath(starts, goal, search, { minX: 0, minY, maxX, maxY }, budget, isFree)
   return path ? { connectorY, points: [...path, end] } : undefined
 }
 
@@ -375,13 +374,27 @@ function expandCompositeBoundsForNotes(diagram: StateDiagram, layout: StateDiagr
     )
     if (descendantNotes.length === 0) continue
 
-    const childBounds = [bound, ...descendantNotes]
-    const noteTop = Math.min(...childBounds.map((child) => child.top), bound.top)
-    const noteBottom = Math.max(...childBounds.map((child) => child.top + child.height), bound.top + bound.height)
-    const left = Math.min(...childBounds.map((child) => child.left)) - 2
-    const top = noteTop < bound.top ? noteTop - 1 : bound.top
-    const right = Math.max(...childBounds.map((child) => child.left + child.width)) + 2
-    const bottom = noteBottom > bound.top + bound.height ? noteBottom + 1 : bound.top + bound.height
+    const connectorPoints = descendantNotes.flatMap((note) => note.connector?.points ?? [])
+    const left = Math.min(
+      bound.left,
+      ...descendantNotes.map((note) => note.left - 2),
+      ...connectorPoints.map((point) => point.x - 1),
+    )
+    const top = Math.min(
+      bound.top,
+      ...descendantNotes.map((note) => note.top - 1),
+      ...connectorPoints.map((point) => point.y - 1),
+    )
+    const right = Math.max(
+      bound.left + bound.width,
+      ...descendantNotes.map((note) => note.left + note.width + 2),
+      ...connectorPoints.map((point) => point.x + 2),
+    )
+    const bottom = Math.max(
+      bound.top + bound.height,
+      ...descendantNotes.map((note) => note.top + note.height + 1),
+      ...connectorPoints.map((point) => point.y + 2),
+    )
 
     bound.left = left
     bound.top = top
@@ -392,13 +405,112 @@ function expandCompositeBoundsForNotes(diagram: StateDiagram, layout: StateDiagr
   }
 }
 
+function expandCompositeBoundsForInternalRouting(diagram: StateDiagram, layout: StateDiagramLayout): void {
+  if (diagram.direction === "LR" || diagram.direction === "RL") return
+  const statesById = new Map(diagram.states.map((state) => [state.id, state]))
+  const compositesById = new Map(diagram.composites.map((composite) => [composite.id, composite]))
+
+  for (const composite of [...diagram.composites].reverse()) {
+    const bound = layout.compositeBounds.get(composite.id)
+    if (!bound) continue
+    const internal = diagram.transitions.filter(
+      (transition) =>
+        transition.from !== transition.to &&
+        innermostCommonCompositeId(transition, statesById, compositesById) === composite.id,
+    )
+    const endpointOccurrences = new Map<string, number>()
+    const sideRoutes = internal.filter((transition) => {
+      const from = layout.bounds.get(transition.from)
+      const to = layout.bounds.get(transition.to)
+      if (!from || !to) return false
+      const key = `${transition.from}\u0000${transition.to}`
+      const occurrence = endpointOccurrences.get(key) ?? 0
+      endpointOccurrences.set(key, occurrence + 1)
+      const fromParent = statesById.get(transition.from)?.parentId
+      const toParent = statesById.get(transition.to)?.parentId
+      return occurrence > 0 || from.centerY > to.centerY || fromParent !== toParent
+    })
+    if (sideRoutes.length === 0) continue
+    const childRight = Math.max(
+      ...diagram.states.flatMap((state) => {
+        if (!belongsToComposite(state.id, composite.id, statesById, compositesById)) return []
+        const child = layout.bounds.get(state.id)
+        return child ? [child.left + child.width] : []
+      }),
+      ...diagram.composites.flatMap((childComposite) => {
+        if (childComposite.parentId !== composite.id) return []
+        const child = layout.compositeBounds.get(childComposite.id)
+        return child ? [child.left + child.width] : []
+      }),
+    )
+    const labelWidth = Math.max(...sideRoutes.map((transition) => measureStateTransitionLabel(transition.label).width))
+    const right = childRight + labelWidth + sideRoutes.length * 3 + 6
+    if (right <= bound.left + bound.width) continue
+    bound.width = right - bound.left
+    bound.centerX = bound.left + Math.floor(bound.width / 2)
+  }
+
+  enforceCompositeMargins(diagram, layout.compositeBounds)
+}
+
+function innermostCommonCompositeId(
+  transition: StateDiagramTransition,
+  statesById: Map<string, StateDiagramState>,
+  compositesById: Map<string, StateDiagramCompositeState>,
+): string | undefined {
+  const containers = (id: string) => {
+    const ids: string[] = []
+    let parentId = statesById.get(id)?.parentId ?? compositesById.get(id)?.parentId
+    while (parentId) {
+      ids.push(parentId)
+      parentId = compositesById.get(parentId)?.parentId
+    }
+    return ids
+  }
+  const target = new Set(containers(transition.to))
+  return containers(transition.from).find((id) => target.has(id))
+}
+
+function enforceCompositeMargins(diagram: StateDiagram, compositeBounds: Map<string, StateDiagramBoxBounds>): void {
+  const compositesByParent = new Map<string, StateDiagramCompositeState[]>()
+  for (const composite of diagram.composites) {
+    if (!composite.parentId) continue
+    const children = compositesByParent.get(composite.parentId) ?? []
+    children.push(composite)
+    compositesByParent.set(composite.parentId, children)
+  }
+
+  const expand = (composite: StateDiagramCompositeState): StateDiagramBoxBounds | undefined => {
+    const bound = compositeBounds.get(composite.id)
+    if (!bound) return undefined
+    const children = (compositesByParent.get(composite.id) ?? [])
+      .map(expand)
+      .filter((child): child is StateDiagramBoxBounds => Boolean(child))
+    if (children.length === 0) return bound
+    const left = Math.min(bound.left, ...children.map((child) => child.left - 2))
+    const top = Math.min(bound.top, ...children.map((child) => child.top - 2))
+    const right = Math.max(bound.left + bound.width, ...children.map((child) => child.left + child.width + 2))
+    const bottom = Math.max(bound.top + bound.height, ...children.map((child) => child.top + child.height + 2))
+    bound.left = left
+    bound.top = top
+    bound.width = right - left
+    bound.height = bottom - top
+    bound.centerX = left + Math.floor(bound.width / 2)
+    bound.centerY = top + Math.floor(bound.height / 2)
+    return bound
+  }
+
+  for (const composite of diagram.composites.filter((candidate) => !candidate.parentId)) expand(composite)
+}
+
 function boundsIntersect(left: StateDiagramBoxBounds, right: StateDiagramBoxBounds): boolean {
   return intersects(left.left, left.top, left.width, left.height, right, 0)
 }
 
-function separateExternalBoundsFromComposites(diagram: StateDiagram, layout: StateDiagramLayout): void {
+export function separateExternalBoundsFromComposites(diagram: StateDiagram, layout: StateDiagramLayout): boolean {
   const statesById = new Map(diagram.states.map((state) => [state.id, state]))
   const compositesById = new Map(diagram.composites.map((composite) => [composite.id, composite]))
+  let shifted = false
 
   for (const composite of diagram.composites) {
     const compositeBound = layout.compositeBounds.get(composite.id)
@@ -433,8 +545,10 @@ function separateExternalBoundsFromComposites(diagram: StateDiagram, layout: Sta
       }
 
       shiftBounds(uniqueBounds(boundsToShift), dx, 0)
+      shifted = true
     }
   }
+  return shifted
 }
 
 function finalizeLayout(
@@ -445,6 +559,7 @@ function finalizeLayout(
   if (diagram.composites.length === 0 && diagram.notes.length === 0) return layout
   addCompositeBounds(diagram, layout)
   normalizeLayout(layout)
+  expandCompositeBoundsForInternalRouting(diagram, layout)
   if (diagram.notes.length > 0) {
     const allBounds = [...layout.bounds.values()]
     placeStateDiagramNotesAroundTransitions(
@@ -464,6 +579,7 @@ function finalizeLayout(
     )
   }
   expandCompositeBoundsForNotes(diagram, layout)
+  expandCompositeBoundsForInternalRouting(diagram, layout)
   separateExternalBoundsFromComposites(diagram, layout)
   normalizeLayout(layout)
   return layout
@@ -479,9 +595,10 @@ export function createStateDiagramLayout(
   }
 
   const ranks = computeRanks(diagram)
+  const maxRank = Math.max(0, ...ranks.values())
   const byRank = new Map<number, StateDiagramState[]>()
   for (const state of diagram.states) {
-    const rank = ranks.get(state.id) ?? 0
+    const rank = diagram.direction === "BT" ? maxRank - (ranks.get(state.id) ?? 0) : (ranks.get(state.id) ?? 0)
     const list = byRank.get(rank) ?? []
     list.push(state)
     byRank.set(rank, list)
@@ -491,9 +608,13 @@ export function createStateDiagramLayout(
   const sizes = new Map(diagram.states.map((state) => [state.id, stateSize(state)]))
   const bounds = new Map<string, StateDiagramBoxBounds>()
   const outgoingLabelRows = new Map<string, number>()
+  const selfTransitionCounts = new Map<string, number>()
   for (const transition of diagram.transitions) {
     const rows = measureStateTransitionLabel(transition.label).height
     outgoingLabelRows.set(transition.from, Math.max(outgoingLabelRows.get(transition.from) ?? 0, rows))
+    if (transition.from === transition.to) {
+      selfTransitionCounts.set(transition.from, (selfTransitionCounts.get(transition.from) ?? 0) + 1)
+    }
   }
 
   const singleColumnCenter = Math.max(
@@ -524,8 +645,12 @@ export function createStateDiagramLayout(
       x += size.width + options.minStateGap + 8
     }
     const labelRows = states.reduce((rows, state) => Math.max(rows, outgoingLabelRows.get(state.id) ?? 0), 0)
+    const selfTransitionRows = states.reduce(
+      (rows, state) => Math.max(rows, (selfTransitionCounts.get(state.id) ?? 0) * 3 + 1),
+      0,
+    )
     const pseudoStateApproachClearance = states.some((state) => state.kind === "choice") ? 2 : 0
-    y += rowHeight + Math.max(4, labelRows + 3) + pseudoStateApproachClearance
+    y += rowHeight + Math.max(4, labelRows + 3, selfTransitionRows) + pseudoStateApproachClearance
   }
 
   return finalizeLayout(diagram, emptyLayout(bounds, sizes), budget)
@@ -805,21 +930,21 @@ function placeStateDiagramNotesAroundTransitions(
           size,
         ),
       ),
-    )
-      .flat()
+    ).flat()
     const findPlacement = (candidateSpace: SpatialIndex, limit: number) => {
       const connectorSearch = createStateSearchSpace(candidateSpace, (role) => (role === "label" ? 1 : 0))
       for (const bound of candidateBounds.slice(0, limit)) {
         if (bound.left < 0) continue
         const owner = `note:${index}`
-        if (!candidateSpace.isFree(spatialRectClaim(`${owner}:body`, owner, "body", bound), { clearance: 1 }))
-          continue
+        if (!candidateSpace.isFree(spatialRectClaim(`${owner}:body`, owner, "body", bound), { clearance: 1 })) continue
         const connector = findNoteConnector(connectorSearch, bound, target, budget)
         if (connector) return { bound: { ...bound, connector }, connector }
       }
       return undefined
     }
     const placement =
+      findPlacement(space, 1) ??
+      findPlacement(noteSpace, 1) ??
       findPlacement(space, MAX_STRICT_NOTE_PLACEMENTS) ??
       findPlacement(reserved, candidateBounds.length) ??
       outsideNotePlacement(noteSpace, note, index, target, size)
@@ -857,10 +982,7 @@ function outsideNotePlacement(
       size,
     )
     const alignedNoteX = position === "left" ? aligned.left + aligned.width : aligned.left - 1
-    const alignedConnectorY = Math.max(
-      aligned.top + 1,
-      Math.min(target.centerY, aligned.top + aligned.height - 2),
-    )
+    const alignedConnectorY = Math.max(aligned.top + 1, Math.min(target.centerY, aligned.top + aligned.height - 2))
     const alignedTargetX = position === "left" ? target.left - 1 : target.left + target.width
     const alignedConnector = {
       connectorY: alignedConnectorY,
@@ -975,16 +1097,30 @@ export function expandCompositeBoundsForInternalTransitions(
         belongsToComposite(plan.route.transition.from, composite.id, statesById, compositesById) &&
         belongsToComposite(plan.route.transition.to, composite.id, statesById, compositesById),
     )
-    const occupiedYs = internalPlans.flatMap((plan) => [
-      ...plan.cells.map((cell) => cell.y),
-      ...(plan.label ? plan.label.lines.map((_, index) => plan.label!.y + index) : []),
+    const occupied = internalPlans.flatMap((plan) => [
+      ...plan.cells.map((cell) => ({ x: cell.x, y: cell.y })),
+      ...(plan.label
+        ? plan.label.lines.flatMap((line, row) =>
+            Array.from({ length: diagramTextWidth(line) }, (_, column) => ({
+              x: plan.label!.x + column,
+              y: plan.label!.y + row,
+            })),
+          )
+        : []),
     ])
-    if (occupiedYs.length === 0) continue
+    if (occupied.length === 0) continue
 
-    const top = Math.min(bound.top, Math.min(...occupiedYs) - 1)
-    const bottom = Math.max(bound.top + bound.height, Math.max(...occupiedYs) + 2)
+    const left = Math.min(bound.left, Math.min(...occupied.map((point) => point.x)) - 1)
+    const top = Math.min(bound.top, Math.min(...occupied.map((point) => point.y)) - 1)
+    const right = Math.max(bound.left + bound.width, Math.max(...occupied.map((point) => point.x)) + 2)
+    const bottom = Math.max(bound.top + bound.height, Math.max(...occupied.map((point) => point.y)) + 2)
+    bound.left = left
     bound.top = top
+    bound.width = right - left
     bound.height = bottom - top
+    bound.centerX = bound.left + Math.floor(bound.width / 2)
     bound.centerY = bound.top + Math.floor(bound.height / 2)
   }
+
+  enforceCompositeMargins(diagram, compositeBounds)
 }

packages/merman/src/state/parser.ts

@@ -16,14 +16,14 @@ const STATE_RE = /^state\s+"([^"]+)"\s+as\s+(\S+)$/i
 const COMPOSITE_STATE_RE = /^state\s+(?:"([^"]+)"\s+as\s+)?(\S+)\s*\{$/i
 const CHOICE_STATE_RE = /^state\s+(\S+)\s+<<choice>>$/i
 const TRANSITION_RE = /^(\[\*\]|[^\s:]+)\s*-->\s*(\[\*\]|[^\s:]+)(?:\s*:\s*(.*))?$/
-const DIRECTION_RE = /^direction\s+(TB|TD|LR|RL)$/i
+const DIRECTION_RE = /^direction\s+(TB|TD|BT|LR|RL)$/i
 const NOTE_INLINE_RE = /^note\s+(left|right)\s+of\s+(\S+)\s*:\s*(.*)$/i
 const NOTE_START_RE = /^note\s+(left|right)\s+of\s+(\S+)\s*$/i
 const NOTE_END_RE = /^end\s+note$/i
 
 function normalizeDirection(value?: string): StateDiagramDirection {
   const upper = value?.toUpperCase()
-  if (upper === "TB" || upper === "TD" || upper === "LR" || upper === "RL") return upper
+  if (upper === "TB" || upper === "TD" || upper === "BT" || upper === "LR" || upper === "RL") return upper
   return DEFAULT_DIRECTION
 }
 

packages/merman/src/state/render-grid.ts

@@ -7,11 +7,12 @@ import type { StateCellStyle } from "./types.js"
 export type StateGrid = DiagramCanvas<StateCellStyle>
 
 export function renderStateGridText(grid: StateGrid): string {
-  return grid.toString({ trimBottom: true })
+  return grid.toString({ trimTop: true, trimBottom: true })
 }
 
 export function renderStateGridStyledText(grid: StateGrid, colors: StateStyleColors): StyledText {
   return renderDiagramGridStyledText(grid, (run) => (run.style ? colors[run.style] : undefined), undefined, {
+    trimTop: true,
     trimBottom: true,
   })
 }

packages/merman/src/state/routing.test.ts

@@ -1,4 +1,5 @@
 import { describe, expect, test } from "bun:test"
+import { diagramTextWidth } from "../core/text.js"
 import type { StateDiagramBoxBounds } from "./layout.js"
 import { createStateDiagramLayout } from "./layout.js"
 import { parseMermaidStateDiagram } from "./parser.js"
@@ -286,10 +287,7 @@ describe("createStateTransitionRenderPlans", () => {
     expect(
       plan.path.some(
         ([x, y]) =>
-          x >= sibling.left &&
-          x < sibling.left + sibling.width &&
-          y >= sibling.top &&
-          y < sibling.top + sibling.height,
+          x >= sibling.left && x < sibling.left + sibling.width && y >= sibling.top && y < sibling.top + sibling.height,
       ),
     ).toBe(false)
   })
@@ -348,6 +346,158 @@ describe("createStateTransitionRenderPlans", () => {
       }),
     ).toBe(true)
   })
+
+  test.each(["LR", "RL", "TB", "TD"] as const)(
+    "keeps endpoint-disjoint %s transitions on separate cells when a detour exists",
+    (direction) => {
+      const diagram = prepareVisibleStateDiagram(
+        parseMermaidStateDiagram(`stateDiagram-v2
+  direction ${direction}
+  state "A" as A
+  state "B" as B
+  state "C" as C
+  state "D" as D
+  B --> D: e0
+  C --> A: e1`),
+      )
+      const layout = createStateDiagramLayout(diagram, { minStateGap: 5 })
+      const plans = createStateTransitionRenderPlans(diagram, layout.bounds, 30)
+      const first = new Set(plans[0]!.path.map(([x, y]) => `${x}:${y}`))
+
+      expect(plans[1]!.path.every(([x, y]) => !first.has(`${x}:${y}`))).toBe(true)
+    },
+  )
+
+  test("anchors labels to final repaired transition geometry", () => {
+    const diagram = prepareVisibleStateDiagram(
+      parseMermaidStateDiagram(`stateDiagram-v2
+  direction TB
+  state "A" as A
+  state "B" as B
+  state "C" as C
+  A --> B: e0
+  A --> C: e1
+  B --> A: e2`),
+    )
+    const layout = createStateDiagramLayout(diagram, { minStateGap: 5 })
+    const plan = createStateTransitionRenderPlans(diagram, layout.bounds, 30).find(
+      (candidate) => candidate.route.transition.label === "e2",
+    )!
+    const width = Math.max(...plan.label!.lines.map(diagramTextWidth))
+    const distance = Math.min(
+      ...plan.path.map(([pathX, pathY]) => {
+        const dx =
+          pathX < plan.label!.x
+            ? plan.label!.x - pathX
+            : pathX >= plan.label!.x + width
+              ? pathX - (plan.label!.x + width - 1)
+              : 0
+        const dy =
+          pathY < plan.label!.y
+            ? plan.label!.y - pathY
+            : pathY >= plan.label!.y + plan.label!.lines.length
+              ? pathY - (plan.label!.y + plan.label!.lines.length - 1)
+              : 0
+        return dx + dy
+      }),
+    )
+
+    expect(plan.pathRepaired).toBe(true)
+    expect(distance).toBeLessThanOrEqual(4)
+  })
+
+  test.each(["LR", "RL", "TB", "TD"] as const)(
+    "allocates distinct connected self-transition lanes in %s diagrams",
+    (direction) => {
+      for (const count of [2, 3, 4]) {
+        const diagram = prepareVisibleStateDiagram(
+          parseMermaidStateDiagram(`stateDiagram-v2
+  direction ${direction}
+${Array.from({ length: count }, (_, index) => `  A --> A: loop-${index}`).join("\n")}`),
+        )
+        const layout = createStateDiagramLayout(diagram, { minStateGap: 5 })
+        const plans = createStateTransitionRenderPlans(diagram, layout.bounds, 30)
+
+        expect(new Set(plans.map((plan) => plan.path.map(([x, y]) => `${x}:${y}`).join("|"))).size).toBe(count)
+        for (const plan of plans) {
+          expect(
+            plan.path.slice(1).every(([x, y], index) => {
+              const previous = plan.path[index]!
+              return Math.abs(x - previous[0]) + Math.abs(y - previous[1]) === 1
+            }),
+          ).toBe(true)
+        }
+      }
+    },
+  )
+
+  test("uses fixed-width side lanes for long parallel vertical labels", () => {
+    const diagram = prepareVisibleStateDiagram(
+      parseMermaidStateDiagram(`stateDiagram-v2
+  direction TB
+  A --> B: alpha route label that is deliberately long
+  A --> B: beta route label that is deliberately long
+  A --> B: gamma route label that is deliberately long`),
+    )
+    const layout = createStateDiagramLayout(diagram, { minStateGap: 5 })
+    const rails = createStateTransitionRoutePlans(diagram, layout.bounds, 30)
+      .filter((plan) => plan.kind === "side-parallel")
+      .map((plan) => plan.railX)
+
+    expect(rails).toHaveLength(2)
+    expect(rails[1]! - rails[0]!).toBe(3)
+  })
+
+  test.each([
+    [
+      "parallel",
+      `stateDiagram-v2
+  direction TB
+  A --> B: alpha route label that is deliberately long
+  A --> B: beta route label that is deliberately long
+  A --> B: gamma route label that is deliberately long`,
+      3,
+    ],
+    [
+      "self",
+      `stateDiagram-v2
+  direction LR
+  A --> A: one
+  A --> A: two
+  A --> A: three`,
+      3,
+    ],
+  ] as const)("keeps %s labels one column clear of frames and route rails", (_, source, count) => {
+    const diagram = prepareVisibleStateDiagram(parseMermaidStateDiagram(source))
+    const layout = createStateDiagramLayout(diagram, { minStateGap: 5 })
+    const plans = createStateTransitionRenderPlans(diagram, layout.bounds, 30)
+    const routeCells = plans.flatMap((plan) => plan.path)
+
+    expect(plans).toHaveLength(count)
+    for (const plan of plans) {
+      const width = Math.max(...plan.label!.lines.map(diagramTextWidth))
+      for (const [row, line] of plan.label!.lines.entries()) {
+        const lineWidth = diagramTextWidth(line)
+        const y = plan.label!.y + row
+        expect(
+          routeCells
+            .filter(([, routeY]) => routeY === y)
+            .every(([routeX]) => routeX < plan.label!.x - 1 || routeX > plan.label!.x + lineWidth),
+        ).toBe(true)
+        for (const bound of layout.bounds.values()) {
+          if (y < bound.top || y >= bound.top + bound.height) continue
+          expect(bound.left + bound.width <= plan.label!.x - 1 || bound.left >= plan.label!.x + width + 1).toBe(true)
+        }
+      }
+    }
+
+    if (source.includes("A --> A")) {
+      const arrowXs = plans
+        .flatMap((plan) => plan.cells.filter((cell) => cell.arrowDirection).map((cell) => cell.x))
+        .sort((left, right) => left - right)
+      expect(arrowXs.slice(1).every((x, index) => x - arrowXs[index]! >= 4)).toBe(true)
+    }
+  })
 })
 
 describe("createStateTransitionJunctionPlans", () => {

packages/merman/src/state/routing.ts

@@ -1,6 +1,6 @@
 import { BorderChars } from "@opentui/core"
 import { diagramLineGlyph } from "../core/drawing.js"
-import type { DiagramDirection } from "../core/geometry.js"
+import { orthogonalPathPoints, type DiagramDirection } from "../core/geometry.js"
 import { SpatialIndex, spatialPathClaim, spatialRectClaim } from "../core/spatial.js"
 import { diagramTextWidth, splitDiagramLines } from "../core/text.js"
 import type { StateDiagramBoxBounds as BoxBounds, StateDiagramNoteBounds } from "./layout.js"
@@ -24,7 +24,7 @@ interface StateTransitionRoutePlanBase {
 }
 
 export type StateTransitionRoutePlan =
-  | (StateTransitionRoutePlanBase & { kind: "self" })
+  | (StateTransitionRoutePlanBase & { kind: "self"; lane: number })
   | (StateTransitionRoutePlanBase & { kind: "horizontal-forward"; leftToRight: boolean })
   | (StateTransitionRoutePlanBase & { kind: "bottom-feedback"; railY: number; approachX: number })
   | (StateTransitionRoutePlanBase & { kind: "top-feedback"; railY: number })
@@ -58,6 +58,7 @@ export interface StateTransitionRenderPlan {
   cells: readonly StateTransitionRenderCell[]
   path: readonly StateTransitionPathPoint[]
   label?: StateTransitionRenderLabel
+  pathRepaired?: boolean
 }
 
 export interface StateTransitionRenderOptions {
@@ -350,6 +351,26 @@ function sideParallelTargetApproach(
   })
 }
 
+function containingCompositeIds(diagram: StateVisibleDiagram, id: string): string[] {
+  const statesById = new Map(diagram.states.map((state) => [state.id, state]))
+  const compositesById = new Map(diagram.composites.map((composite) => [composite.id, composite]))
+  const ids: string[] = []
+  let parentId = statesById.get(id)?.parentId ?? compositesById.get(id)?.parentId
+  while (parentId) {
+    ids.push(parentId)
+    parentId = compositesById.get(parentId)?.parentId
+  }
+  return ids
+}
+
+function innermostCommonComposite(
+  diagram: StateVisibleDiagram,
+  transition: StateVisibleTransition,
+): string | undefined {
+  const target = new Set(containingCompositeIds(diagram, transition.to))
+  return containingCompositeIds(diagram, transition.from).find((id) => target.has(id))
+}
+
 export function createStateTransitionRoutePlans(
   diagram: StateVisibleDiagram,
   bounds: ReadonlyMap<string, BoxBounds>,
@@ -358,11 +379,13 @@ export function createStateTransitionRoutePlans(
 ): StateTransitionRoutePlan[] {
   const statesById = new Map(diagram.states.map((state) => [state.id, state]))
   const endpointOccurrences = new Map<string, number>()
+  const selfOccurrences = new Map<string, number>()
   const parallelLaneGap = Math.max(
     3,
     ...diagram.transitions.map((transition) => measureStateTransitionLabel(transition.label).height + 2),
   )
   let nextSideRailX = Math.max(0, ...[...bounds.values()].map((bound) => bound.left + bound.width)) + 3
+  const sideRailLanes = new Map<string, number>()
   const feedbackAllocations = createFeedbackAllocations(diagram, bounds, feedbackLaneY, parallelLaneGap, feedbackTopY)
   let nextBottomRailY =
     Math.max(
@@ -371,9 +394,24 @@ export function createStateTransitionRoutePlans(
         .filter((allocation) => allocation.side === "bottom")
         .map((allocation) => allocation.railY),
     ) + parallelLaneGap
-  const allocateSideRail = (label: string): number => {
+  const allocateSideRail = (transition: StateVisibleTransition): number => {
+    const compositeId = innermostCommonComposite(diagram, transition)
+    const composite = compositeId ? bounds.get(compositeId) : undefined
+    if (compositeId && composite) {
+      const lane = sideRailLanes.get(compositeId) ?? 0
+      sideRailLanes.set(compositeId, lane + 1)
+      const descendantRight = Math.max(
+        composite.left + 1,
+        ...diagram.states.flatMap((state) => {
+          if (!containingCompositeIds(diagram, state.id).includes(compositeId)) return []
+          const bound = bounds.get(state.id)
+          return bound ? [bound.left + bound.width] : []
+        }),
+      )
+      return Math.min(descendantRight + 2 + lane * 3, composite.left + composite.width - 2)
+    }
     const railX = nextSideRailX
-    nextSideRailX += Math.max(3, measureStateTransitionLabel(label).width + 2)
+    nextSideRailX += 3
     return railX
   }
   const allocateBottomRail = (): number => {
@@ -392,7 +430,7 @@ export function createStateTransitionRoutePlans(
     const targetIsHiddenMarker = isHiddenCompositeMarker(targetState)
     const base = { transition, from, to, targetIsChoice, targetIsHiddenMarker }
     const sideParallel = (): StateTransitionRoutePlan => {
-      const railX = allocateSideRail(transition.label)
+      const railX = allocateSideRail(transition)
       return {
         ...base,
         kind: "side-parallel",
@@ -400,7 +438,11 @@ export function createStateTransitionRoutePlans(
         targetApproach: sideParallelTargetApproach(diagram, transition, from, to, bounds, railX),
       }
     }
-    if (transition.from === transition.to) return [{ ...base, kind: "self" }]
+    if (transition.from === transition.to) {
+      const lane = selfOccurrences.get(transition.from) ?? 0
+      selfOccurrences.set(transition.from, lane + 1)
+      return [{ ...base, kind: "self", lane }]
+    }
     const endpointKey = `${transition.from}\u0000${transition.to}`
     const parallelIndex = endpointOccurrences.get(endpointKey) ?? 0
     endpointOccurrences.set(endpointKey, parallelIndex + 1)
@@ -449,7 +491,8 @@ export function createStateTransitionRoutePlans(
       if (verticalCorridorCrossesUnrelatedState(diagram, transition, from, to, bounds)) {
         return [sideParallel()]
       }
-      if (from.centerY > to.centerY) {
+      const verticalFeedback = diagram.direction === "BT" ? from.centerY < to.centerY : from.centerY > to.centerY
+      if (verticalFeedback) {
         return [sideParallel()]
       }
       if (from.centerY === to.centerY) {
@@ -612,33 +655,36 @@ function addHorizontalForward(builder: StateTransitionRenderBuilder): void {
 }
 
 function addSelfTransition(builder: StateTransitionRenderBuilder): void {
-  const { from: bounds, transition } = builder.route
+  const { from: bounds, transition, lane } = builder.route as Extract<StateTransitionRoutePlan, { kind: "self" }>
   if (bounds.width <= 1 || bounds.height <= 1) {
-    const railX = bounds.left + 4
-    const railY = bounds.top + 2
+    const railX = bounds.left + 4 + lane * 4
+    const railY = bounds.top + 2 + lane * 2
     addHorizontalLine(builder, bounds.left + 1, railX - 1, bounds.top, 1)
     addCell(builder, { x: railX, y: bounds.top, char: "╮" })
-    addCell(builder, { x: railX, y: bounds.top + 1, char: "│" })
+    addVerticalLine(builder, railX, bounds.top + 1, railY - 1, 1)
     addCell(builder, { x: railX, y: railY, char: "╯" })
     addHorizontalLine(builder, railX - 1, bounds.left + 1, railY, -1)
     addCell(builder, { x: bounds.left, y: railY, char: "╰" })
+    for (let y = railY - 1; y > bounds.top + 1; y--) addCell(builder, { x: bounds.left, y, char: "│" })
     addCell(builder, { x: bounds.left, y: bounds.top + 1, arrowDirection: "up" })
     addPathPoint(builder, bounds.left, bounds.top)
-    if (transition.label) addLabel(builder, railX + 2, bounds.top + 1, transition.label)
+    if (transition.label) addLabel(builder, railX + 2, lane === 0 ? bounds.top + 1 : railY - 1, transition.label)
     return
   }
   const sourceX = bounds.left + Math.max(2, Math.floor(bounds.width / 3))
   const bottomY = bounds.top + bounds.height - 1
-  const railY = bottomY + 2
-  const targetX = Math.max(sourceX + 3, bounds.left + Math.min(bounds.width - 3, Math.ceil((bounds.width * 2) / 3)))
+  const railY = bottomY + 2 + lane * 3
+  const targetX =
+    Math.max(sourceX + 3, bounds.left + Math.min(bounds.width - 3, Math.ceil((bounds.width * 2) / 3))) + lane * 4
 
   addBottomDeparture(builder, bounds, sourceX)
-  addCell(builder, { x: sourceX, y: bottomY + 1, char: "│" })
+  addVerticalLine(builder, sourceX, bottomY + 1, railY - 1, 1)
   addCell(builder, { x: sourceX, y: railY, char: "╰" })
   for (let x = sourceX + 1; x < targetX; x++) addCell(builder, { x, y: railY, char: "─" })
   addCell(builder, { x: targetX, y: railY, char: "╯" })
+  for (let y = railY - 1; y > bottomY + 1; y--) addCell(builder, { x: targetX, y, char: "│" })
   addCell(builder, { x: targetX, y: bottomY + 1, arrowDirection: "up" })
-  if (transition.label) addLabel(builder, targetX + 2, bottomY + 1, transition.label)
+  if (transition.label) addLabel(builder, targetX + 2, lane === 0 ? bottomY + 1 : railY - 1, transition.label)
 }
 
 function outsideBottomY(bounds: BoxBounds): number {
@@ -732,10 +778,8 @@ function addTopFeedbackTransition(builder: StateTransitionRenderBuilder): void {
 }
 
 function addSideParallelTransition(builder: StateTransitionRenderBuilder): void {
-  const { from, to, targetIsChoice, targetIsHiddenMarker, transition, railX, targetApproach } = builder.route as Extract<
-    StateTransitionRoutePlan,
-    { kind: "side-parallel" }
-  >
+  const { from, to, targetIsChoice, targetIsHiddenMarker, transition, railX, targetApproach } =
+    builder.route as Extract<StateTransitionRoutePlan, { kind: "side-parallel" }>
   const startX = from.left + from.width
   const startY = from.centerY
   const endY = targetApproach === "top" ? to.top - 2 : targetApproach === "bottom" ? to.top + to.height + 1 : to.centerY
@@ -757,7 +801,12 @@ function addSideParallelTransition(builder: StateTransitionRenderBuilder): void
     if (targetIsChoice || targetIsHiddenMarker) addPathPoint(builder, to.left, to.top)
     if (transition.label) {
       const metrics = measureStateTransitionLabel(transition.label)
-      addLabel(builder, railX + 2, Math.max(0, Math.floor((startY + to.centerY - metrics.height + 1) / 2)), transition.label)
+      addLabel(
+        builder,
+        railX + 2,
+        Math.max(0, Math.floor((startY + to.centerY - metrics.height + 1) / 2)),
+        transition.label,
+      )
     }
     return
   }
@@ -938,31 +987,62 @@ function routeIntersectsUnrelatedState(
       "boundary",
       stateDiagramNoteConnector(noteBound, target).points,
     )
-    return plan.path.some(([x, y]) =>
-      connector.spans.some((span) => span.y === y && x >= span.fromX && x <= span.toX),
-    )
+    return plan.path.some(([x, y]) => connector.spans.some((span) => span.y === y && x >= span.fromX && x <= span.toX))
   })
 }
 
 function findBodySafePath(
   start: StateTransitionPathPoint,
   end: StateTransitionPathPoint,
+  diagram: StateVisibleDiagram,
   bounds: ReadonlyMap<string, BoxBounds>,
   plan: StateTransitionRenderPlan,
   search: StateSearchSpace,
   budget: StateSearchBudget,
 ): StateTransitionPathPoint[] | undefined {
   const margin = Math.max(8, bounds.size * 2)
+  const compositeId = innermostCommonComposite(diagram, plan.route.transition)
+  const composite = compositeId ? bounds.get(compositeId) : undefined
+  const searchBounds = {
+    minX: composite ? composite.left + 1 : search.minX - margin,
+    minY: composite ? composite.top + 1 : Math.min(search.minY, ...plan.path.map((point) => point[1])) - margin,
+    maxX: composite
+      ? composite.left + composite.width - 2
+      : Math.max(search.maxX, ...plan.path.map((point) => point[0])) + margin,
+    maxY: composite
+      ? composite.top + composite.height - 2
+      : Math.max(search.maxY, ...plan.path.map((point) => point[1])) + margin,
+  }
+  const isFree = ([x, y]: StateTransitionPathPoint) =>
+    x >= searchBounds.minX &&
+    x <= searchBounds.maxX &&
+    y >= searchBounds.minY &&
+    y <= searchBounds.maxY &&
+    !search.blocked.has(`${x}:${y}`)
+  const pathMinX = Math.min(...plan.path.map((point) => point[0]))
+  const pathMinY = Math.min(...plan.path.map((point) => point[1]))
+  const pathMaxX = Math.max(...plan.path.map((point) => point[0]))
+  const pathMaxY = Math.max(...plan.path.map((point) => point[1]))
+  const directCandidates: StateTransitionPathPoint[][] = [
+    [start, [start[0], end[1]] as const, end],
+    [start, [end[0], start[1]] as const, end],
+    ...Array.from({ length: 4 }, (_, index) => index + 1).flatMap((offset): StateTransitionPathPoint[][] => [
+      [start, [start[0], pathMinY - offset], [end[0], pathMinY - offset], end],
+      [start, [start[0], pathMaxY + offset], [end[0], pathMaxY + offset], end],
+      [start, [pathMinX - offset, start[1]], [pathMinX - offset, end[1]], end],
+      [start, [pathMaxX + offset, start[1]], [pathMaxX + offset, end[1]], end],
+    ]),
+  ]
+  const direct = directCandidates
+    .map((points) => orthogonalPathPoints(points.map(([x, y]) => ({ x, y }))).map(({ x, y }) => [x, y] as const))
+    .filter((points) => points.every(isFree))
+    .sort((left, right) => left.length - right.length)[0]
+  if (direct) return direct
   const path = findStateManhattanPath(
     [{ x: start[0], y: start[1] }],
     { x: end[0], y: end[1] },
     search,
-    {
-      minX: search.minX - margin,
-      minY: Math.min(search.minY, ...plan.path.map((point) => point[1])) - margin,
-      maxX: Math.max(search.maxX, ...plan.path.map((point) => point[0])) + margin,
-      maxY: Math.max(search.maxY, ...plan.path.map((point) => point[1])) + margin,
-    },
+    searchBounds,
     budget,
   )
   return path?.map((point) => [point.x, point.y] as const)
@@ -975,17 +1055,29 @@ function bodySafeTransitionPlan(
   noteBounds: readonly StateDiagramNoteBounds[],
   search: StateSearchSpace,
   budget: StateSearchBudget,
+  forceRepair = false,
 ): StateTransitionRenderPlan {
-  if (!routeIntersectsUnrelatedState(plan, diagram, bounds, noteBounds)) return plan
+  if (!forceRepair && !routeIntersectsUnrelatedState(plan, diagram, bounds, noteBounds)) return plan
   const sourceOutsideIndex = plan.path.findIndex((point) => !pointIsInsideBounds(point, plan.route.from))
   const targetOutsideIndex = plan.path.findLastIndex((point) => !pointIsInsideBounds(point, plan.route.to))
   if (sourceOutsideIndex < 0 || targetOutsideIndex < sourceOutsideIndex) return plan
-  const safePath = findBodySafePath(plan.path[sourceOutsideIndex]!, plan.path[targetOutsideIndex]!, bounds, plan, search, budget)
+  const safePath = findBodySafePath(
+    plan.path[sourceOutsideIndex]!,
+    plan.path[targetOutsideIndex]!,
+    diagram,
+    bounds,
+    plan,
+    search,
+    budget,
+  )
   if (!safePath) return alternateBodySafeTransitionPlan(plan, diagram, bounds, noteBounds, search, budget)
 
   const prefix = plan.path.slice(0, sourceOutsideIndex)
   const suffix = plan.path.slice(targetOutsideIndex + 1)
-  return renderBodySafeTransitionPlan(plan, safePath, prefix, suffix)
+  const repaired = renderBodySafeTransitionPlan(plan, safePath, prefix, suffix)
+  if (safePath.length <= plan.path.length + 4) return repaired
+  const alternate = alternateBodySafeTransitionPlan(plan, diagram, bounds, noteBounds, search, budget)
+  return alternate !== plan && alternate.path.length < repaired.path.length ? alternate : repaired
 }
 
 function alternateBodySafeTransitionPlan(
@@ -996,9 +1088,10 @@ function alternateBodySafeTransitionPlan(
   search: StateSearchSpace,
   budget: StateSearchBudget,
 ): StateTransitionRenderPlan {
+  const candidates: StateTransitionRenderPlan[] = []
   for (const source of stateRoutePorts(plan.route.from)) {
     for (const target of stateRoutePorts(plan.route.to)) {
-      const safePath = findBodySafePath(source.outside, target.outside, bounds, plan, search, budget)
+      const safePath = findBodySafePath(source.outside, target.outside, diagram, bounds, plan, search, budget)
       if (!safePath) continue
       const prefix = plan.route.from.width > 1 && plan.route.from.height > 1 ? [source.border] : []
       const suffix =
@@ -1006,10 +1099,10 @@ function alternateBodySafeTransitionPlan(
           ? ([[plan.route.to.left, plan.route.to.top]] as const)
           : []
       const repaired = renderBodySafeTransitionPlan(plan, safePath, prefix, suffix, source.char)
-      if (!routeIntersectsUnrelatedState(repaired, diagram, bounds, noteBounds)) return repaired
+      if (!routeIntersectsUnrelatedState(repaired, diagram, bounds, noteBounds)) candidates.push(repaired)
     }
   }
-  return plan
+  return candidates.sort((left, right) => left.path.length - right.path.length)[0] ?? plan
 }
 
 function stateRoutePorts(bounds: BoxBounds): Array<{
@@ -1072,7 +1165,50 @@ function renderBodySafeTransitionPlan(
     cells.push({ x: point[0], y: point[1], char: diagramLineGlyph(connections, "rounded") })
   }
 
-  return { ...plan, cells, path: fullPath }
+  return { ...plan, cells, path: fullPath, pathRepaired: true }
+}
+
+function labelDistanceToPath(
+  x: number,
+  y: number,
+  width: number,
+  height: number,
+  path: readonly StateTransitionPathPoint[],
+): number {
+  return Math.min(
+    ...path.map(([pathX, pathY]) => {
+      const dx = pathX < x ? x - pathX : pathX >= x + width ? pathX - (x + width - 1) : 0
+      const dy = pathY < y ? y - pathY : pathY >= y + height ? pathY - (y + height - 1) : 0
+      return dx + dy
+    }),
+  )
+}
+
+function stateTransitionLabelCandidates(
+  plan: StateTransitionRenderPlan,
+  width: number,
+  height: number,
+): Array<{ x: number; y: number }> {
+  const candidates = new Map<string, { x: number; y: number }>()
+  const add = (x: number, y: number) => candidates.set(`${x}:${y}`, { x, y })
+  if (
+    plan.label &&
+    (!plan.pathRepaired || labelDistanceToPath(plan.label.x, plan.label.y, width, height, plan.path) <= 4)
+  ) {
+    add(plan.label.x, plan.label.y)
+  }
+  for (const [x, y] of plan.path) {
+    add(x + 2, y - Math.floor(height / 2))
+    add(x - width - 2, y - Math.floor(height / 2))
+    add(x - Math.floor(width / 2), y - height - 1)
+    add(x - Math.floor(width / 2), y + 2)
+  }
+  const preferred = plan.label ?? { x: plan.path[0]?.[0] ?? 0, y: plan.path[0]?.[1] ?? 0 }
+  return [...candidates.values()].sort((left, right) => {
+    const leftDistance = Math.abs(left.x - preferred.x) + Math.abs(left.y - preferred.y)
+    const rightDistance = Math.abs(right.x - preferred.x) + Math.abs(right.y - preferred.y)
+    return leftDistance - rightDistance
+  })
 }
 
 function placeStateTransitionLabels(
@@ -1096,6 +1232,19 @@ function placeStateTransitionLabels(
         plan.path.map(([x, y]) => ({ x, y })),
       ),
     ),
+    ...diagram.composites.flatMap((composite) => {
+      const bound = bounds.get(composite.id)
+      if (!bound) return []
+      return [
+        spatialPathClaim(`composite:${composite.id}`, `composite:${composite.id}`, "boundary", [
+          { x: bound.left, y: bound.top },
+          { x: bound.left + bound.width - 1, y: bound.top },
+          { x: bound.left + bound.width - 1, y: bound.top + bound.height - 1 },
+          { x: bound.left, y: bound.top + bound.height - 1 },
+          { x: bound.left, y: bound.top },
+        ]),
+      ]
+    }),
     ...noteBounds.flatMap((noteBound) => {
       const target = bounds.get(noteBound.note.target)
       return [
@@ -1114,10 +1263,25 @@ function placeStateTransitionLabels(
     }),
   )
 
-  return plans.map((plan, planIndex) => {
-    if (!plan.label) return plan
+  const placed = new Map<number, StateTransitionRenderPlan>()
+  const endpointCounts = new Map<string, number>()
+  for (const plan of plans) {
+    const key = `${plan.route.transition.from}\u0000${plan.route.transition.to}`
+    endpointCounts.set(key, (endpointCounts.get(key) ?? 0) + 1)
+  }
+  const placementOrder = [...plans.keys()].sort(
+    (left, right) => Number(Boolean(plans[left]!.pathRepaired)) - Number(Boolean(plans[right]!.pathRepaired)),
+  )
+  for (const planIndex of placementOrder) {
+    const plan = plans[planIndex]!
+    if (!plan.label) {
+      placed.set(planIndex, plan)
+      continue
+    }
     const width = Math.max(...plan.label.lines.map(diagramTextWidth))
-    const statePadding = plan.label.lines.length === 1 ? 0 : 1
+    const endpointKey = `${plan.route.transition.from}\u0000${plan.route.transition.to}`
+    const needsLaneClearance = (endpointCounts.get(endpointKey) ?? 0) > 1
+    const statePadding = needsLaneClearance || plan.label.lines.length > 1 ? 1 : 0
     const labelClaim = (x: number, y: number) =>
       spatialRectClaim(`label:${planIndex}`, `label:${planIndex}`, "label", {
         left: x,
@@ -1131,19 +1295,35 @@ function placeStateTransitionLabels(
         clearance: {
           body: statePadding,
           label: { x: 1, y: 0 },
+          route:
+            plan.pathRepaired || plan.route.kind === "side-parallel" || needsLaneClearance
+              ? {
+                  x: 1,
+                  y: 0,
+                }
+              : 0,
         },
       })
     }
 
-    let x = plan.label.x
-    let y = plan.label.y
-    if (!isClear(x, y)) {
+    const candidates = stateTransitionLabelCandidates(plan, width, plan.label.lines.length)
+    const nearby = candidates.find(
+      (candidate) =>
+        (!(plan.pathRepaired || plan.route.kind === "side-parallel" || needsLaneClearance) ||
+          labelDistanceToPath(candidate.x, candidate.y, width, plan.label!.lines.length, plan.path) >= 2) &&
+        isClear(candidate.x, candidate.y),
+    )
+    let x = nearby?.x ?? candidates[0]?.x ?? plan.label.x
+    let y = nearby?.y ?? candidates[0]?.y ?? plan.label.y
+    if (!nearby) {
       search: for (let distance = 1; distance < 500; distance++) {
         for (let dx = -distance; dx <= distance; dx++) {
           const dy = distance - Math.abs(dx)
           for (const candidateY of dy === 0 ? [y] : [y - dy, y + dy]) {
             const candidateX = x + dx
             if (!isClear(candidateX, candidateY)) continue
+            const pathDistance = labelDistanceToPath(candidateX, candidateY, width, plan.label!.lines.length, plan.path)
+            if (pathDistance < 2 || pathDistance > 8) continue
             x = candidateX
             y = candidateY
             break search
@@ -1151,10 +1331,26 @@ function placeStateTransitionLabels(
         }
       }
     }
+    if (!isClear(x, y)) {
+      fallback: for (let distance = 1; distance < 500; distance++) {
+        for (let dx = -distance; dx <= distance; dx++) {
+          const dy = distance - Math.abs(dx)
+          for (const candidateY of dy === 0 ? [y] : [y - dy, y + dy]) {
+            const candidateX = x + dx
+            if (!isClear(candidateX, candidateY)) continue
+            x = candidateX
+            y = candidateY
+            break fallback
+          }
+        }
+      }
+    }
+    if (!isClear(x, y)) throw new Error(`Transition ${endpointKey} has no clear label position`)
 
     space = space.add(labelClaim(x, y))
-    return { ...plan, label: { ...plan.label, x, y } }
-  })
+    placed.set(planIndex, { ...plan, label: { ...plan.label, x, y } })
+  }
+  return plans.map((plan, index) => placed.get(index) ?? plan)
 }
 
 export function createStateTransitionRenderPlans(
@@ -1169,15 +1365,59 @@ export function createStateTransitionRenderPlans(
     createStateTransitionRenderPlan,
   )
   if (options.repairRoutes === false) return placeStateTransitionLabels(plans, diagram, bounds, noteBounds)
-  const routeSpace = createStateSearchSpace(transitionObstacles(diagram, bounds, noteBounds))
-  return placeStateTransitionLabels(
-    plans.map((plan) => bodySafeTransitionPlan(plan, diagram, bounds, noteBounds, routeSpace, budget)),
-    diagram,
-    bounds,
-    noteBounds,
+  const baseObstacles = transitionObstacles(diagram, bounds, noteBounds)
+  const repaired: StateTransitionRenderPlan[] = []
+  for (const [index, plan] of plans.entries()) {
+    const disjoint = repaired.filter((previous) => transitionsHaveDisjointEndpoints(previous, plan))
+    const routeObstacles = repaired.filter(
+      (previous) => disjoint.includes(previous) || transitionsAreReciprocal(previous, plan),
+    )
+    const routeSpace = createStateSearchSpace(
+      baseObstacles.add(
+        ...routeObstacles.map((previous, previousIndex) =>
+          spatialPathClaim(
+            `transition:${index}:obstacle:${previousIndex}`,
+            `transition:${index}:obstacle:${previousIndex}`,
+            "route",
+            previous.path.map(([x, y]) => ({ x, y })),
+          ),
+        ),
+      ),
+    )
+    repaired.push(
+      bodySafeTransitionPlan(
+        plan,
+        diagram,
+        bounds,
+        noteBounds,
+        routeSpace,
+        budget,
+        disjoint.some((previous) => pathsIntersect(previous.path, plan.path)),
+      ),
+    )
+  }
+  return placeStateTransitionLabels(repaired, diagram, bounds, noteBounds)
+}
+
+function transitionsHaveDisjointEndpoints(left: StateTransitionRenderPlan, right: StateTransitionRenderPlan): boolean {
+  const leftEndpoints = new Set([left.route.transition.from, left.route.transition.to])
+  return !leftEndpoints.has(right.route.transition.from) && !leftEndpoints.has(right.route.transition.to)
+}
+
+function transitionsAreReciprocal(left: StateTransitionRenderPlan, right: StateTransitionRenderPlan): boolean {
+  return (
+    left.route.transition.from === right.route.transition.to && left.route.transition.to === right.route.transition.from
   )
 }
 
+function pathsIntersect(
+  left: readonly StateTransitionPathPoint[],
+  right: readonly StateTransitionPathPoint[],
+): boolean {
+  const occupied = new Set(left.map(([x, y]) => `${x}:${y}`))
+  return right.some(([x, y]) => occupied.has(`${x}:${y}`))
+}
+
 function transitionObstacles(
   diagram: StateVisibleDiagram,
   bounds: ReadonlyMap<string, BoxBounds>,

packages/merman/src/state/types.ts

@@ -1,6 +1,6 @@
 import type { BorderStyle } from "@opentui/core"
 
-export type StateDiagramDirection = "TB" | "TD" | "LR" | "RL"
+export type StateDiagramDirection = "TB" | "TD" | "BT" | "LR" | "RL"
 export type StateDiagramArrowHeadStyle = "filled" | "line"
 
 export interface StateDiagramState {
@@ -41,6 +41,8 @@ export interface StateDiagramRenderOptions {
   borderStyle?: BorderStyle
   arrowHeadStyle?: StateDiagramArrowHeadStyle
   minStateGap?: number
+  /** Target rendered width. Oversized horizontal layouts fold vertically. */
+  layoutMaxWidth?: number
 }
 
 export type NoteConnectorRampStyle = `noteConnectorRamp${1 | 2 | 3}`

packages/merman/src/test/layout-audit/fixtures.ts

@@ -0,0 +1,493 @@
+import type { FlowchartDirection } from "../../flowchart/types.js"
+import type { StateDiagramDirection } from "../../state/types.js"
+
+export type LayoutFixture = {
+  id: string
+  kind: "flowchart" | "state"
+  family: string
+  profile: LabelProfile
+  source: string
+  curated?: boolean
+}
+
+type LabelProfile = "short" | "long" | "unicode"
+
+const flowVariants = [
+  ["TB", "short"],
+  ["TD", "long"],
+  ["BT", "unicode"],
+  ["LR", "short"],
+  ["RL", "long"],
+  ["TB", "unicode"],
+  ["TD", "short"],
+  ["BT", "long"],
+  ["LR", "unicode"],
+  ["RL", "short"],
+  ["LR", "long"],
+  ["TD", "unicode"],
+  ["TB", "long"],
+  ["BT", "short"],
+  ["RL", "unicode"],
+] as const satisfies readonly (readonly [FlowchartDirection, LabelProfile])[]
+
+const stateVariants = [
+  ["TB", "short"],
+  ["TD", "long"],
+  ["LR", "unicode"],
+  ["RL", "short"],
+  ["TB", "long"],
+  ["TD", "unicode"],
+  ["LR", "short"],
+  ["RL", "long"],
+  ["LR", "long"],
+  ["TD", "short"],
+  ["TB", "unicode"],
+  ["RL", "unicode"],
+  ["BT", "short"],
+  ["BT", "long"],
+  ["BT", "unicode"],
+] as const satisfies readonly (readonly [StateDiagramDirection, LabelProfile])[]
+
+function nodeLabel(id: string, profile: LabelProfile): string {
+  if (profile === "long") return `${id} deliberate deployment stage with a long descriptive label`
+  if (profile === "unicode") return `${id} 東京<br/>résumé 🚀`
+  return `${id} node`
+}
+
+function edgeLabel(id: string, profile: LabelProfile): string {
+  if (profile === "long") return `${id} transition carrying detailed deployment context`
+  if (profile === "unicode") return `${id} 東京<br/>✓ prêt`
+  return `${id} edge`
+}
+
+function flowNode(id: string, profile: LabelProfile): string {
+  return `  ${id}["${nodeLabel(id, profile)}"]`
+}
+
+function flowEdge(from: string, to: string, id: string, profile: LabelProfile): string {
+  return `  ${from} -->|"${edgeLabel(id, profile)}"| ${to}`
+}
+
+function flowSource(
+  direction: FlowchartDirection,
+  profile: LabelProfile,
+  nodes: readonly string[],
+  edges: readonly [from: string, to: string, id: string][],
+  extra: readonly string[] = [],
+): string {
+  return [
+    `flowchart ${direction}`,
+    ...nodes.map((id) => flowNode(id, profile)),
+    ...extra,
+    ...edges.map(([from, to, id]) => flowEdge(from, to, id, profile)),
+  ].join("\n")
+}
+
+const flowFamilies = {
+  chain(direction: FlowchartDirection, profile: LabelProfile) {
+    return flowSource(
+      direction,
+      profile,
+      ["A", "B", "C", "D", "E", "F"],
+      [
+        ["A", "B", "E01"],
+        ["B", "C", "E02"],
+        ["C", "D", "E03"],
+        ["D", "E", "E04"],
+        ["E", "F", "E05"],
+      ],
+    )
+  },
+  fork(direction: FlowchartDirection, profile: LabelProfile) {
+    return flowSource(
+      direction,
+      profile,
+      ["A", "B", "C", "D", "E"],
+      [
+        ["A", "B", "E01"],
+        ["A", "C", "E02"],
+        ["A", "D", "E03"],
+        ["A", "E", "E04"],
+      ],
+    )
+  },
+  join(direction: FlowchartDirection, profile: LabelProfile) {
+    return flowSource(
+      direction,
+      profile,
+      ["A", "B", "C", "D", "E"],
+      [
+        ["A", "E", "E01"],
+        ["B", "E", "E02"],
+        ["C", "E", "E03"],
+        ["D", "E", "E04"],
+      ],
+    )
+  },
+  cycle(direction: FlowchartDirection, profile: LabelProfile) {
+    return flowSource(
+      direction,
+      profile,
+      ["A", "B", "C", "D"],
+      [
+        ["A", "B", "E01"],
+        ["B", "C", "E02"],
+        ["C", "D", "E03"],
+        ["D", "A", "E04"],
+        ["C", "A", "E05"],
+      ],
+    )
+  },
+  crossing(direction: FlowchartDirection, profile: LabelProfile) {
+    return flowSource(
+      direction,
+      profile,
+      ["A", "B", "C", "D", "E", "F"],
+      [
+        ["A", "C", "E01"],
+        ["A", "D", "E02"],
+        ["B", "C", "E03"],
+        ["B", "D", "E04"],
+        ["C", "E", "E05"],
+        ["D", "F", "E06"],
+      ],
+    )
+  },
+  parallel(direction: FlowchartDirection, profile: LabelProfile) {
+    return flowSource(
+      direction,
+      profile,
+      ["A", "B", "C"],
+      [
+        ["A", "B", "E01"],
+        ["A", "B", "E02"],
+        ["A", "B", "E03"],
+        ["B", "C", "E04"],
+        ["B", "C", "E05"],
+      ],
+    )
+  },
+  self(direction: FlowchartDirection, profile: LabelProfile) {
+    return flowSource(
+      direction,
+      profile,
+      ["A", "B", "C"],
+      [
+        ["A", "A", "E01"],
+        ["A", "B", "E02"],
+        ["B", "B", "E03"],
+        ["B", "C", "E04"],
+      ],
+    )
+  },
+  subgraph(direction: FlowchartDirection, profile: LabelProfile) {
+    return [
+      `flowchart ${direction}`,
+      `  subgraph Left["Left ${nodeLabel("SG1", profile)}"]`,
+      flowNode("A", profile),
+      flowNode("B", profile),
+      "  end",
+      `  subgraph Right["Right ${nodeLabel("SG2", profile)}"]`,
+      flowNode("C", profile),
+      flowNode("D", profile),
+      "  end",
+      flowEdge("A", "B", "E01", profile),
+      flowEdge("A", "C", "E02", profile),
+      flowEdge("B", "D", "E03", profile),
+      flowEdge("C", "D", "E04", profile),
+    ].join("\n")
+  },
+  "nested-subgraph"(direction: FlowchartDirection, profile: LabelProfile) {
+    const local = direction === "LR" || direction === "RL" ? "TB" : "LR"
+    return [
+      `flowchart ${direction}`,
+      `  subgraph Outer["Outer ${nodeLabel("SG1", profile)}"]`,
+      `    direction ${local}`,
+      `    subgraph Inner["Inner ${nodeLabel("SG2", profile)}"]`,
+      flowNode("A", profile),
+      flowNode("B", profile),
+      "    end",
+      flowNode("C", profile),
+      "  end",
+      flowNode("D", profile),
+      flowEdge("A", "B", "E01", profile),
+      flowEdge("A", "C", "E02", profile),
+      flowEdge("B", "D", "E03", profile),
+      flowEdge("C", "D", "E04", profile),
+    ].join("\n")
+  },
+} satisfies Record<string, (direction: FlowchartDirection, profile: LabelProfile) => string>
+
+function stateDeclaration(id: string, profile: LabelProfile, indent = "  "): string {
+  return `${indent}state "${nodeLabel(id, profile)}" as ${id}`
+}
+
+function stateTransition(from: string, to: string, id: string, profile: LabelProfile, indent = "  "): string {
+  return `${indent}${from} --> ${to}: ${edgeLabel(id, profile)}`
+}
+
+function stateSource(
+  direction: StateDiagramDirection,
+  profile: LabelProfile,
+  states: readonly string[],
+  transitions: readonly [from: string, to: string, id: string][],
+  extra: readonly string[] = [],
+): string {
+  return [
+    "stateDiagram-v2",
+    `  direction ${direction}`,
+    ...states.map((id) => stateDeclaration(id, profile)),
+    ...extra,
+    ...transitions.map(([from, to, id]) => stateTransition(from, to, id, profile)),
+  ].join("\n")
+}
+
+const stateFamilies = {
+  chain(direction: StateDiagramDirection, profile: LabelProfile) {
+    return stateSource(
+      direction,
+      profile,
+      ["A", "B", "C", "D", "E"],
+      [
+        ["A", "B", "E01"],
+        ["B", "C", "E02"],
+        ["C", "D", "E03"],
+        ["D", "E", "E04"],
+      ],
+      ["  [*] --> A", "  E --> [*]"],
+    )
+  },
+  fork(direction: StateDiagramDirection, profile: LabelProfile) {
+    return stateSource(
+      direction,
+      profile,
+      ["A", "B", "C", "D"],
+      [
+        ["A", "B", "E01"],
+        ["A", "C", "E02"],
+        ["A", "D", "E03"],
+      ],
+    )
+  },
+  join(direction: StateDiagramDirection, profile: LabelProfile) {
+    return stateSource(
+      direction,
+      profile,
+      ["A", "B", "C", "D"],
+      [
+        ["A", "D", "E01"],
+        ["B", "D", "E02"],
+        ["C", "D", "E03"],
+      ],
+    )
+  },
+  cycle(direction: StateDiagramDirection, profile: LabelProfile) {
+    return stateSource(
+      direction,
+      profile,
+      ["A", "B", "C", "D"],
+      [
+        ["A", "B", "E01"],
+        ["B", "C", "E02"],
+        ["C", "D", "E03"],
+        ["D", "A", "E04"],
+        ["C", "A", "E05"],
+      ],
+    )
+  },
+  crossing(direction: StateDiagramDirection, profile: LabelProfile) {
+    return stateSource(
+      direction,
+      profile,
+      ["A", "B", "C", "D"],
+      [
+        ["A", "C", "E01"],
+        ["A", "D", "E02"],
+        ["B", "C", "E03"],
+        ["B", "D", "E04"],
+      ],
+    )
+  },
+  parallel(direction: StateDiagramDirection, profile: LabelProfile) {
+    return stateSource(
+      direction,
+      profile,
+      ["A", "B", "C"],
+      [
+        ["A", "B", "E01"],
+        ["A", "B", "E02"],
+        ["A", "B", "E03"],
+        ["B", "C", "E04"],
+      ],
+    )
+  },
+  self(direction: StateDiagramDirection, profile: LabelProfile) {
+    return stateSource(
+      direction,
+      profile,
+      ["A", "B", "C"],
+      [
+        ["A", "A", "E01"],
+        ["A", "B", "E02"],
+        ["B", "B", "E03"],
+        ["B", "C", "E04"],
+      ],
+    )
+  },
+  choice(direction: StateDiagramDirection, profile: LabelProfile) {
+    return stateSource(
+      direction,
+      profile,
+      ["A", "B", "C"],
+      [
+        ["A", "Choice", "E01"],
+        ["Choice", "B", "E02"],
+        ["Choice", "C", "E03"],
+        ["C", "A", "E04"],
+      ],
+      ["  state Choice <<choice>>"],
+    )
+  },
+  notes(direction: StateDiagramDirection, profile: LabelProfile) {
+    return stateSource(
+      direction,
+      profile,
+      ["A", "B", "C"],
+      [
+        ["A", "B", "E01"],
+        ["B", "C", "E02"],
+        ["C", "A", "E03"],
+      ],
+      [
+        `  note left of A: ${edgeLabel("N01", profile)}`,
+        `  note right of B: ${edgeLabel("N02", profile)}`,
+        `  note right of C: ${edgeLabel("N03", profile)}`,
+      ],
+    )
+  },
+  composite(direction: StateDiagramDirection, profile: LabelProfile) {
+    return [
+      "stateDiagram-v2",
+      `  direction ${direction}`,
+      `  state "${nodeLabel("Outer", profile)}" as Outer {`,
+      stateDeclaration("A", profile, "    "),
+      stateDeclaration("B", profile, "    "),
+      "    [*] --> A",
+      stateTransition("A", "B", "E01", profile, "    "),
+      "    B --> [*]",
+      "  }",
+      stateDeclaration("Done", profile),
+      stateTransition("Outer", "Done", "E02", profile),
+      `  note right of B: ${edgeLabel("N01", profile)}`,
+    ].join("\n")
+  },
+  "nested-composite"(direction: StateDiagramDirection, profile: LabelProfile) {
+    return [
+      "stateDiagram-v2",
+      `  direction ${direction}`,
+      `  state "${nodeLabel("Session", profile)}" as Session {`,
+      "    [*] --> Open",
+      `    state "${nodeLabel("Open", profile)}" as Open {`,
+      stateDeclaration("Clean", profile, "      "),
+      stateDeclaration("Dirty", profile, "      "),
+      "      [*] --> Clean",
+      stateTransition("Clean", "Dirty", "E01", profile, "      "),
+      stateTransition("Dirty", "Clean", "E02", profile, "      "),
+      "      Dirty --> [*]",
+      "    }",
+      "    Open --> [*]",
+      "  }",
+      stateDeclaration("Done", profile),
+      stateTransition("Session", "Done", "E03", profile),
+      `  note right of Dirty: ${edgeLabel("N01", profile)}`,
+    ].join("\n")
+  },
+} satisfies Record<string, (direction: StateDiagramDirection, profile: LabelProfile) => string>
+
+export const deploymentArchitectureSource = `flowchart LR
+    Client[OpenCode client]
+
+    subgraph CF[Cloudflare]
+      DNS[opencode.ai]
+      Web[Console frontend Worker]
+      Proxy[Console API proxy Worker]
+      Infer[inference-next Worker]
+      KV[Model registry KV]
+      Redis[Upstash Redis]
+      Logs[Axiom / Cloudflare logs]
+      Lake[Pipeline to R2 data lake]
+    end
+
+    subgraph AWS[AWS]
+      EKS[EKS cluster]
+      API[Console API pod<br/>1 replica]
+      OTEL[OTel collector]
+      ECR[ECR]
+    end
+
+    DB[(PlanetScale)]
+    Models[Anthropic / OpenAI / other providers]
+
+    Client -->|/inference/*| DNS --> Infer
+    Client -->|/console/*| DNS --> Web
+    Web -->|/console/api, /auth, etc.| Proxy
+    Proxy -->|Cloudflare VPC service| API
+
+    Infer -->|public DATABASE_URL| DB
+    Infer --> KV
+    Infer --> Redis
+    Infer --> Models
+    Infer --> Logs
+    Infer --> Lake
+
+    API -->|private DATABASE_AWS_URL| DB
+    API --> OTEL
+    ECR --> API`
+
+export function layoutFixtures(): readonly LayoutFixture[] {
+  const flowcharts = Object.entries(flowFamilies).flatMap(([family, source]) =>
+    flowVariants.map(([direction, profile]) => ({
+      id: `flowchart/${family}/${direction.toLowerCase()}-${profile}`,
+      kind: "flowchart" as const,
+      family,
+      profile,
+      source: source(direction, profile),
+    })),
+  )
+  const states = Object.entries(stateFamilies).flatMap(([family, source]) =>
+    stateVariants.map(([direction, profile]) => ({
+      id: `state/${family}/${direction.toLowerCase()}-${profile}`,
+      kind: "state" as const,
+      family,
+      profile,
+      source: source(direction, profile),
+    })),
+  )
+  return [
+    ...flowcharts,
+    {
+      id: "flowchart/deployment-architecture/curated",
+      kind: "flowchart" as const,
+      family: "deployment-architecture",
+      profile: "short" as const,
+      source: deploymentArchitectureSource,
+      curated: true,
+    },
+    {
+      id: "flowchart/grouped-fanout/curated",
+      kind: "flowchart" as const,
+      family: "grouped-fanout",
+      profile: "short" as const,
+      source: `flowchart TD
+  subgraph Group
+    S[Source]
+    S -->|route 0 detail| N0[Node 0]
+    S -->|route 1 detail| N1[Node 1]
+    S -->|route 2 detail| N2[Node 2]
+    S -->|route 3 detail| N3[Node 3]
+  end`,
+      curated: true,
+    },
+    ...states,
+  ]
+}

packages/merman/src/test/layout-audit/harness.ts

@@ -0,0 +1,521 @@
+import { orthogonalPathPoints, segmentBetween, type DiagramPoint } from "../../core/geometry.js"
+import { SpatialIndex, spatialPathClaim, spatialRectClaim } from "../../core/spatial.js"
+import { diagramTextWidth } from "../../core/text.js"
+import { splitDiagramLines } from "../../core/text-lines.js"
+import { drawFlowchartDiagramGrid } from "../../flowchart/drawing.js"
+import { layoutFlowchartDiagram } from "../../flowchart/layout.js"
+import { flowchartRouteLabelLayout } from "../../flowchart/labels.js"
+import { parseMermaidFlowchartDiagram } from "../../flowchart/parser.js"
+import { createStateDiagramDrawing } from "../../state/drawing.js"
+import type { StateDiagramBoxBounds } from "../../state/layout.js"
+import { stateDiagramNoteConnector } from "../../state/note.js"
+import { parseMermaidStateDiagram } from "../../state/parser.js"
+import type { StateTransitionRenderPlan } from "../../state/routing.js"
+import { isHiddenCompositeMarker } from "../../state/visible-model.js"
+import { layoutFixtures, type LayoutFixture } from "./fixtures.js"
+
+export const auditViewports = [60, 80, 120] as const
+
+export type LayoutMetrics = {
+  width: number
+  height: number
+  area: number
+  routeLength: number
+  bends: number
+  crossings: number
+  sharedRouteCells: number
+  overflow: number
+}
+
+export type LayoutAudit = {
+  fixture: LayoutFixture
+  viewport: (typeof auditViewports)[number]
+  output: string
+  metrics: LayoutMetrics
+  violations: string[]
+}
+
+type Bounds = Pick<StateDiagramBoxBounds, "left" | "top" | "width" | "height">
+type AuditedRoute = {
+  from: string
+  to: string
+  points: readonly DiagramPoint[]
+}
+
+function finiteBounds(bounds: Bounds): boolean {
+  return (
+    [bounds.left, bounds.top, bounds.width, bounds.height].every(Number.isFinite) &&
+    bounds.width > 0 &&
+    bounds.height > 0
+  )
+}
+
+function boundsOverlap(left: Bounds, right: Bounds): boolean {
+  return (
+    left.left < right.left + right.width &&
+    left.left + left.width > right.left &&
+    left.top < right.top + right.height &&
+    left.top + left.height > right.top
+  )
+}
+
+function boundsContain(outer: Bounds, inner: Bounds): boolean {
+  return (
+    inner.left >= outer.left &&
+    inner.top >= outer.top &&
+    inner.left + inner.width <= outer.left + outer.width &&
+    inner.top + inner.height <= outer.top + outer.height
+  )
+}
+
+function pointInBounds(point: DiagramPoint, bounds: Bounds): boolean {
+  return (
+    point.x >= bounds.left &&
+    point.x < bounds.left + bounds.width &&
+    point.y >= bounds.top &&
+    point.y < bounds.top + bounds.height
+  )
+}
+
+function pointTouchesBounds(point: DiagramPoint, bounds: Bounds): boolean {
+  if (pointInBounds(point, bounds)) return true
+  return (
+    ((point.x === bounds.left - 1 || point.x === bounds.left + bounds.width) &&
+      point.y >= bounds.top &&
+      point.y < bounds.top + bounds.height) ||
+    ((point.y === bounds.top - 1 || point.y === bounds.top + bounds.height) &&
+      point.x >= bounds.left &&
+      point.x < bounds.left + bounds.width)
+  )
+}
+
+function isOrthogonal(points: readonly DiagramPoint[]): boolean {
+  return points.every((point, index) => {
+    if (
+      !Number.isFinite(point.x) ||
+      !Number.isFinite(point.y) ||
+      !Number.isInteger(point.x) ||
+      !Number.isInteger(point.y)
+    )
+      return false
+    const previous = points[index - 1]
+    return !previous || previous.x === point.x || previous.y === point.y
+  })
+}
+
+function expandedPath(points: readonly DiagramPoint[]): DiagramPoint[] {
+  if (!isOrthogonal(points)) return []
+  return orthogonalPathPoints(points)
+}
+
+function routeLength(points: readonly DiagramPoint[]): number {
+  return routeSegments(points).reduce((total, segment) => total + segment.length, 0)
+}
+
+function routeBends(points: readonly DiagramPoint[]): number {
+  const directions = points.slice(1).flatMap((point, index) => {
+    const previous = points[index]
+    if (point.x === previous.x && point.y !== previous.y) return ["y"]
+    if (point.y === previous.y && point.x !== previous.x) return ["x"]
+    return []
+  })
+  return directions.slice(1).filter((axis, index) => axis !== directions[index]).length
+}
+
+function routeSegments(points: readonly DiagramPoint[]) {
+  return points.slice(1).flatMap((point, index) => segmentBetween(points[index]!, point) ?? [])
+}
+
+function crossingCount(routes: readonly AuditedRoute[]): number {
+  let count = 0
+  for (const [index, route] of routes.entries()) {
+    for (const other of routes.slice(index + 1)) {
+      for (const segment of routeSegments(route.points)) {
+        for (const otherSegment of routeSegments(other.points)) {
+          if (segment.axis === otherSegment.axis) continue
+          const horizontal = segment.axis === "x" ? segment : otherSegment
+          const vertical = segment.axis === "y" ? segment : otherSegment
+          const x = vertical.from.x
+          const y = horizontal.from.y
+          const horizontalMin = Math.min(horizontal.from.x, horizontal.to.x)
+          const horizontalMax = Math.max(horizontal.from.x, horizontal.to.x)
+          const verticalMin = Math.min(vertical.from.y, vertical.to.y)
+          const verticalMax = Math.max(vertical.from.y, vertical.to.y)
+          if (x <= horizontalMin || x >= horizontalMax || y <= verticalMin || y >= verticalMax) continue
+          count++
+        }
+      }
+    }
+  }
+  return count
+}
+
+function sharedRouteCellCount(routes: readonly AuditedRoute[]): number {
+  let count = 0
+  const cells = routes.map((route) => new Set(expandedPath(route.points).map((point) => `${point.x}:${point.y}`)))
+  for (const [index, routeCells] of cells.entries()) {
+    for (const other of cells.slice(index + 1)) {
+      for (const cell of routeCells) if (other.has(cell)) count++
+    }
+  }
+  return count
+}
+
+function metrics(
+  width: number,
+  height: number,
+  routes: readonly AuditedRoute[],
+  viewport: (typeof auditViewports)[number],
+): LayoutMetrics {
+  return {
+    width,
+    height,
+    area: width * height,
+    routeLength: routes.reduce((total, route) => total + routeLength(route.points), 0),
+    bends: routes.reduce((total, route) => total + routeBends(route.points), 0),
+    crossings: crossingCount(routes),
+    sharedRouteCells: sharedRouteCellCount(routes),
+    overflow: Math.max(0, width - viewport),
+  }
+}
+
+function requireOutputLines(output: string, lines: readonly string[], owner: string, violations: string[]): void {
+  for (const line of lines.map((line) => line.trim()).filter(Boolean)) {
+    if (!output.includes(line)) violations.push(`${owner} content missing: ${JSON.stringify(line)}`)
+  }
+}
+
+function validateRoutes(
+  routes: readonly AuditedRoute[],
+  bounds: ReadonlyMap<string, Bounds>,
+  bodyIds: readonly string[],
+  violations: string[],
+): void {
+  for (const [index, route] of routes.entries()) {
+    if (route.points.length < 2) {
+      violations.push(`route ${index} ${route.from}->${route.to} is empty`)
+      continue
+    }
+    if (!isOrthogonal(route.points))
+      violations.push(`route ${index} ${route.from}->${route.to} is not finite and orthogonal`)
+    const from = bounds.get(route.from)
+    const to = bounds.get(route.to)
+    if (!from || !to) {
+      violations.push(`route ${index} ${route.from}->${route.to} has a missing endpoint bound`)
+      continue
+    }
+    if (!pointTouchesBounds(route.points[0], from))
+      violations.push(`route ${index} does not touch source ${route.from}`)
+    if (!pointTouchesBounds(route.points.at(-1)!, to))
+      violations.push(`route ${index} does not touch target ${route.to}`)
+    if (!isOrthogonal(route.points)) continue
+    const bodySpace = SpatialIndex.empty().add(
+      ...bodyIds.flatMap((id) => {
+        const bound = bounds.get(id)
+        return id === route.from || id === route.to || !bound
+          ? []
+          : [spatialRectClaim(`body:${id}`, `body:${id}`, "body", bound)]
+      }),
+    )
+    const conflicts = bodySpace.conflicts(spatialPathClaim(`route:${index}`, `route:${index}`, "route", route.points))
+    for (const id of new Set(conflicts.map((conflict) => conflict.existing.owner.slice("body:".length)))) {
+      violations.push(`route ${index} ${route.from}->${route.to} intersects unrelated body ${id}`)
+    }
+  }
+}
+
+function validateBodies(bounds: ReadonlyMap<string, Bounds>, ids: readonly string[], violations: string[]): void {
+  let occupied = SpatialIndex.empty()
+  for (const id of ids) {
+    const bound = bounds.get(id)
+    if (!bound) {
+      violations.push(`missing body bound ${id}`)
+      continue
+    }
+    if (!finiteBounds(bound)) {
+      violations.push(`body ${id} has invalid bounds`)
+      continue
+    }
+    const claim = spatialRectClaim(`body:${id}`, `body:${id}`, "body", bound)
+    for (const otherId of new Set(
+      occupied.conflicts(claim).map((conflict) => conflict.existing.owner.slice("body:".length)),
+    )) {
+      violations.push(`bodies ${id} and ${otherId} overlap`)
+    }
+    occupied = occupied.add(claim)
+  }
+}
+
+function auditFlowchart(fixture: LayoutFixture, viewport: (typeof auditViewports)[number]): LayoutAudit {
+  const violations: string[] = []
+  const diagram = parseMermaidFlowchartDiagram(fixture.source)
+  const layout = layoutFlowchartDiagram(diagram, { compact: true, layoutMaxWidth: viewport })
+  const grid = drawFlowchartDiagramGrid(diagram, { compact: true, layoutMaxWidth: viewport })
+  const output = grid.toString({ trimTop: true, trimBottom: true })
+  const size = grid.getTextSize({ trimTop: true, trimBottom: true })
+  const routes = layout.routes.map((route) => ({ from: route.edge.from, to: route.edge.to, points: route.points }))
+  const bodyIds = layout.diagram.nodes.map((node) => node.id)
+
+  if (!Number.isFinite(size.width) || !Number.isFinite(size.height) || size.width <= 0 || size.height <= 0)
+    violations.push("rendered grid has invalid dimensions")
+  if (!Number.isFinite(layout.width) || !Number.isFinite(layout.height) || layout.width <= 0 || layout.height <= 0)
+    violations.push("layout has invalid dimensions")
+  if (layout.routes.length !== layout.diagram.edges.filter((edge) => !edge.orderOnly).length)
+    violations.push("rendered route count does not match visible edge count")
+  validateBodies(layout.bounds, bodyIds, violations)
+  validateRoutes(routes, layout.bounds, bodyIds, violations)
+
+  for (const node of layout.diagram.nodes)
+    requireOutputLines(output, layout.bounds.get(node.id)?.lines ?? [], `node ${node.id}`, violations)
+  for (const route of layout.routes) {
+    if (!route.edge.label) continue
+    requireOutputLines(
+      output,
+      flowchartRouteLabelLayout(route, diagramTextWidth).lines,
+      `edge ${route.edge.from}->${route.edge.to}`,
+      violations,
+    )
+    const targets = new Set(
+      layout.diagram.edges.filter((edge) => edge.label && edge.from === route.edge.from).map((edge) => edge.to),
+    )
+    const sources = new Set(
+      layout.diagram.edges.filter((edge) => edge.label && edge.to === route.edge.to).map((edge) => edge.from),
+    )
+    const label = flowchartRouteLabelLayout(route, diagramTextWidth)
+    if (
+      fixture.family === "grouped-fanout" &&
+      (targets.size > 1 || sources.size > 1) &&
+      label.point.x + label.width > viewport
+    ) {
+      violations.push(`grouped edge ${route.edge.from}->${route.edge.to} label exceeds viewport`)
+    }
+  }
+  for (const subgraph of layout.diagram.subgraphs ?? []) {
+    const bound = layout.subgraphBounds.get(subgraph.id)
+    if (!bound || !finiteBounds(bound)) violations.push(`subgraph ${subgraph.id} has invalid bounds`)
+    requireOutputLines(output, splitDiagramLines(subgraph.label), `subgraph ${subgraph.id}`, violations)
+    for (const nodeId of subgraph.nodeIds) {
+      const node = layout.bounds.get(nodeId)
+      if (bound && node && !boundsContain(bound, node))
+        violations.push(`subgraph ${subgraph.id} does not contain ${nodeId}`)
+    }
+  }
+  const subgraphs = layout.diagram.subgraphs ?? []
+  const subgraphById = new Map(subgraphs.map((subgraph) => [subgraph.id, subgraph]))
+  const ancestorOf = (ancestor: string, id: string) => {
+    let parentId = subgraphById.get(id)?.parentId
+    while (parentId) {
+      if (parentId === ancestor) return true
+      parentId = subgraphById.get(parentId)?.parentId
+    }
+    return false
+  }
+  for (const [index, subgraph] of subgraphs.entries()) {
+    const bound = layout.subgraphBounds.get(subgraph.id)
+    if (!bound) continue
+    for (const other of subgraphs.slice(index + 1)) {
+      if (ancestorOf(subgraph.id, other.id) || ancestorOf(other.id, subgraph.id)) continue
+      const otherBound = layout.subgraphBounds.get(other.id)
+      if (otherBound && boundsOverlap(bound, otherBound)) {
+        violations.push(`subgraphs ${subgraph.id} and ${other.id} overlap`)
+      }
+    }
+  }
+
+  return { fixture, viewport, output, metrics: metrics(size.width, size.height, routes, viewport), violations }
+}
+
+function stateRoute(route: StateTransitionRenderPlan): AuditedRoute {
+  return {
+    from: route.route.transition.from,
+    to: route.route.transition.to,
+    points: route.path.map(([x, y]) => ({ x, y })),
+  }
+}
+
+function auditState(fixture: LayoutFixture, viewport: (typeof auditViewports)[number]): LayoutAudit {
+  const violations: string[] = []
+  const parsed = parseMermaidStateDiagram(fixture.source)
+  const drawing = createStateDiagramDrawing(parsed, { minStateGap: 5, layoutMaxWidth: viewport })
+  const diagram = drawing.diagram
+  const layout = drawing.layout
+  const plans = drawing.transitionPlans
+  const grid = drawing.grid
+  const routes = plans.map(stateRoute)
+  const output = grid.toString({ trimTop: true, trimBottom: true })
+  const size = grid.getTextSize({ trimTop: true, trimBottom: true })
+  const bodyIds = diagram.states.filter((state) => !isHiddenCompositeMarker(state)).map((state) => state.id)
+
+  if (!Number.isFinite(size.width) || !Number.isFinite(size.height) || size.width <= 0 || size.height <= 0)
+    violations.push("rendered grid has invalid dimensions")
+  if (plans.length !== diagram.transitions.length)
+    violations.push("rendered route count does not match visible transition count")
+  validateBodies(layout.bounds, bodyIds, violations)
+  validateRoutes(routes, layout.bounds, bodyIds, violations)
+  if (diagram.direction === "BT" && fixture.family === "chain") {
+    for (const transition of diagram.transitions) {
+      if (transition.from === transition.to) continue
+      const from = layout.bounds.get(transition.from)
+      const to = layout.bounds.get(transition.to)
+      if (from && to && from.centerY <= to.centerY) {
+        violations.push(`BT transition ${transition.from}->${transition.to} does not travel upward`)
+      }
+    }
+  }
+
+  for (const state of diagram.states) {
+    if (isHiddenCompositeMarker(state)) continue
+    requireOutputLines(output, layout.sizes.get(state.id)?.lines ?? [state.label], `state ${state.id}`, violations)
+  }
+  for (const plan of plans) {
+    if (!plan.route.transition.label) continue
+    if (!plan.label)
+      violations.push(`transition ${plan.route.transition.from}->${plan.route.transition.to} has no label layout`)
+    requireOutputLines(
+      output,
+      plan.label?.lines ?? [],
+      `transition ${plan.route.transition.from}->${plan.route.transition.to}`,
+      violations,
+    )
+  }
+
+  const statesById = new Map(diagram.states.map((state) => [state.id, state]))
+  const compositesById = new Map(diagram.composites.map((composite) => [composite.id, composite]))
+  const descendantOf = (id: string, compositeId: string) => {
+    let parentId = statesById.get(id)?.parentId ?? compositesById.get(id)?.parentId
+    while (parentId) {
+      if (parentId === compositeId) return true
+      parentId = compositesById.get(parentId)?.parentId
+    }
+    return false
+  }
+  for (const composite of diagram.composites) {
+    const bound = layout.compositeBounds.get(composite.id)
+    if (!bound || !finiteBounds(bound)) {
+      violations.push(`composite ${composite.id} has invalid bounds`)
+      continue
+    }
+    requireOutputLines(output, splitDiagramLines(composite.label), `composite ${composite.id}`, violations)
+    for (const state of diagram.states.filter(
+      (state) => !isHiddenCompositeMarker(state) && descendantOf(state.id, composite.id),
+    )) {
+      const stateBound = layout.bounds.get(state.id)
+      if (stateBound && !boundsContain(bound, stateBound))
+        violations.push(`composite ${composite.id} does not contain ${state.id}`)
+    }
+  }
+
+  for (const [index, note] of layout.noteBounds.entries()) {
+    if (!finiteBounds(note)) violations.push(`note ${index} has invalid bounds`)
+    requireOutputLines(output, note.lines, `note ${index}`, violations)
+    for (const id of bodyIds) {
+      const bound = layout.bounds.get(id)
+      if (bound && boundsOverlap(note, bound)) violations.push(`note ${index} overlaps state ${id}`)
+    }
+    for (const other of layout.noteBounds.slice(index + 1)) {
+      if (boundsOverlap(note, other)) violations.push(`notes ${index} and ${other.id} overlap`)
+    }
+    const target = layout.bounds.get(note.note.target)
+    if (!target) {
+      violations.push(`note ${index} has no target bound`)
+      continue
+    }
+    for (const point of expandedPath(stateDiagramNoteConnector(note, target).points)) {
+      for (const id of bodyIds) {
+        if (id === note.note.target) continue
+        const bound = layout.bounds.get(id)
+        if (bound && pointInBounds(point, bound)) violations.push(`note ${index} connector intersects state ${id}`)
+      }
+      for (const other of layout.noteBounds) {
+        if (other === note) continue
+        if (pointInBounds(point, other)) violations.push(`note ${index} connector intersects note ${other.id}`)
+      }
+    }
+  }
+
+  return { fixture, viewport, output, metrics: metrics(size.width, size.height, routes, viewport), violations }
+}
+
+export function auditFixture(fixture: LayoutFixture, viewport: (typeof auditViewports)[number] = 120): LayoutAudit {
+  return fixture.kind === "flowchart" ? auditFlowchart(fixture, viewport) : auditState(fixture, viewport)
+}
+
+export function auditAllFixtures(): LayoutAudit[] {
+  return layoutFixtures().flatMap((fixture, index) => {
+    if (fixture.curated) return auditViewports.map((viewport) => auditFixture(fixture, viewport))
+    if (fixture.kind === "flowchart") {
+      return auditFixture(fixture, auditViewports[index % auditViewports.length])
+    }
+    const viewport = fixture.profile === "short" ? 60 : fixture.profile === "unicode" ? 80 : 120
+    return auditFixture(fixture, viewport)
+  })
+}
+
+function percentile(values: readonly number[], ratio: number): number {
+  if (values.length === 0) return 0
+  return [...values].sort((left, right) => left - right)[Math.ceil(values.length * ratio) - 1] ?? 0
+}
+
+export function summarizeAudits(audits: readonly LayoutAudit[]) {
+  const summarize = (selected: readonly LayoutAudit[]) => ({
+    runs: selected.length,
+    sources: new Set(selected.map((audit) => audit.fixture.id)).size,
+    violations: selected.reduce((total, audit) => total + audit.violations.length, 0),
+    area: {
+      p50: percentile(
+        selected.map((audit) => audit.metrics.area),
+        0.5,
+      ),
+      p95: percentile(
+        selected.map((audit) => audit.metrics.area),
+        0.95,
+      ),
+      max: Math.max(0, ...selected.map((audit) => audit.metrics.area)),
+    },
+    bends: {
+      p95: percentile(
+        selected.map((audit) => audit.metrics.bends),
+        0.95,
+      ),
+      max: Math.max(0, ...selected.map((audit) => audit.metrics.bends)),
+    },
+    crossings: {
+      total: selected.reduce((total, audit) => total + audit.metrics.crossings, 0),
+      max: Math.max(0, ...selected.map((audit) => audit.metrics.crossings)),
+    },
+    routeLength: {
+      p95: percentile(
+        selected.map((audit) => audit.metrics.routeLength),
+        0.95,
+      ),
+      max: Math.max(0, ...selected.map((audit) => audit.metrics.routeLength)),
+    },
+    sharedRouteCells: {
+      p95: percentile(
+        selected.map((audit) => audit.metrics.sharedRouteCells),
+        0.95,
+      ),
+      max: Math.max(0, ...selected.map((audit) => audit.metrics.sharedRouteCells)),
+    },
+    overflow: {
+      p95: percentile(
+        selected.map((audit) => audit.metrics.overflow),
+        0.95,
+      ),
+      max: Math.max(0, ...selected.map((audit) => audit.metrics.overflow)),
+    },
+  })
+  return {
+    total: summarize(audits),
+    flowchart: summarize(audits.filter((audit) => audit.fixture.kind === "flowchart")),
+    state: summarize(audits.filter((audit) => audit.fixture.kind === "state")),
+  }
+}
+
+export function worstAudits(audits: readonly LayoutAudit[], metric: keyof LayoutMetrics, limit = 10): LayoutAudit[] {
+  return [...audits]
+    .sort(
+      (left, right) => right.metrics[metric] - left.metrics[metric] || left.fixture.id.localeCompare(right.fixture.id),
+    )
+    .slice(0, limit)
+}

packages/merman/src/test/markdown.test.ts

@@ -334,6 +334,33 @@ flowchart LR
   expect(testRenderer.captureCharFrame()).toContain("GLOBAL registry")
 })
 
+test("folds a horizontal state diagram to the Markdown context width", async () => {
+  const testRenderer = await createTestRenderer({ width: 60, height: 48 })
+  renderer = testRenderer.renderer
+  const markdown = new MarkdownRenderable(renderer, {
+    id: "markdown-horizontal-state",
+    content: `\`\`\`mermaid
+stateDiagram-v2
+  direction LR
+  [*] --> A
+  A --> B: first
+  B --> C: second
+  C --> D: third
+  D --> [*]
+\`\`\``,
+    syntaxStyle,
+    renderNode: createMermaidMarkdownRenderer(renderer),
+  })
+
+  renderer.root.add(markdown)
+  await renderMarkdown(markdown, testRenderer.renderOnce)
+
+  const diagram = markdown.getChildren()[0] as CodeRenderable
+  expect(diagram.scrollWidth).toBeLessThanOrEqual(diagram.width)
+  expect(diagram.scrollWidth).toBeLessThanOrEqual(60)
+  expect(testRenderer.captureCharFrame()).toContain("third")
+})
+
 test("renders a Mermaid state fence inside MarkdownRenderable", async () => {
   const testRenderer = await createTestRenderer({ width: 80, height: 14 })
   renderer = testRenderer.renderer
@@ -357,6 +384,27 @@ stateDiagram-v2
   expect(frame).not.toContain("stateDiagram-v2")
 })
 
+test("sizes a standalone state choice after trimming leading rows", async () => {
+  const testRenderer = await createTestRenderer({ width: 80, height: 6 })
+  renderer = testRenderer.renderer
+  const markdown = new MarkdownRenderable(renderer, {
+    id: "markdown-state-choice",
+    content: `\`\`\`mermaid
+stateDiagram-v2
+  direction LR
+  state Decision <<choice>>
+\`\`\``,
+    syntaxStyle,
+    renderNode: createMermaidMarkdownRenderer(renderer),
+  })
+
+  renderer.root.add(markdown)
+  await renderMarkdown(markdown, testRenderer.renderOnce)
+
+  expect(markdown.getChildren()[0]?.height).toBe(1)
+  expect(testRenderer.captureCharFrame()).toContain("◆")
+})
+
 test("renders a Mermaid timeline fence inside MarkdownRenderable", async () => {
   const testRenderer = await createTestRenderer({ width: 80, height: 18 })
   renderer = testRenderer.renderer

packages/plugin/src/effect/command.ts

@@ -1,16 +1,27 @@
 import type { CommandApi } from "@opencode-ai/client/effect/api"
-import type { CommandInfo } from "@opencode-ai/client"
+import type { PromptInput } from "@opencode-ai/schema/prompt-input"
+import type { Session } from "@opencode-ai/schema/session"
+import type { SessionInbox } from "@opencode-ai/schema/session-inbox"
 import type { Effect } from "effect"
 import type { Transform } from "./registration.js"
 
-export interface CommandDraft {
-  list(): readonly CommandInfo[]
-  get(name: string): CommandInfo | undefined
-  update(name: string, update: (command: CommandInfo) => void): void
-  remove(name: string): void
+export interface CommandInvocation {
+  readonly sessionID: Session.ID
+  readonly prompt: PromptInput.Prompt
+  readonly delivery: SessionInbox.Delivery
 }
 
-export interface CommandDomain extends CommandApi<unknown> {
+export interface CommandDefinition {
+  readonly name: string
+  readonly description?: string
+  readonly execute: (input: CommandInvocation) => Effect.Effect<void, unknown>
+}
+
+export interface CommandDraft {
+  add(definition: CommandDefinition): void
+}
+
+export interface CommandDomain extends Pick<CommandApi<unknown>, "list"> {
   readonly transform: Transform<CommandDraft>
   readonly reload: () => Effect.Effect<void>
 }

packages/plugin/src/promise/adapter.ts

@@ -1,5 +1,6 @@
 import { Tool } from "@opencode-ai/schema/tool"
-import { Effect, Schema, SchemaAST, Scope, Stream } from "effect"
+import { Effect, Schema, SchemaAST, Stream } from "effect"
+import type { Scope } from "effect"
 import { HttpApiEndpoint, HttpApiSchema } from "effect/unstable/httpapi"
 import { define } from "../effect/plugin.js"
 import type { Context, Plugin } from "./plugin.js"
@@ -84,12 +85,11 @@ export function fromPromise(plugin: Plugin) {
         const SessionEndpoints = ClientApi.groups["server.session"].endpoints
         const SkillEndpoints = ClientApi.groups["server.skill"].endpoints
         const WebSearchEndpoints = ClientApi.groups["server.websearch"].endpoints
-        const scope = yield* Scope.Scope
         const context = yield* Effect.context<Scope.Scope>()
 
         // Run a hook registration on the plugin scope and resolve once it is registered.
         const register = (effect: Effect.Effect<HostRegistration, never, Scope.Scope>): Promise<Registration> =>
-          Effect.runPromiseWith(context)(Scope.provide(scope)(effect)).then((registration) => ({
+          Effect.runPromiseWith(context)(effect).then((registration) => ({
             dispose: () => Effect.runPromiseWith(context)(registration.dispose),
           }))
 
@@ -149,7 +149,19 @@ export function fromPromise(plugin: Plugin) {
           },
           command: {
             list: adaptApiMethod(CommandEndpoints["command.list"], host.command.list),
-            transform: transform(host.command),
+            transform: (callback) =>
+              register(
+                host.command.transform((draft) =>
+                  callback({
+                    add: (definition) =>
+                      draft.add({
+                        ...definition,
+                        execute: (input) =>
+                          Effect.tryPromise({ try: () => definition.execute(input), catch: (cause) => cause }),
+                      }),
+                  }),
+                ),
+              ),
             reload: () => run(host.command.reload()),
           },
           event: {
@@ -325,9 +337,10 @@ export function fromPromise(plugin: Plugin) {
           },
         }
 
-        const cleanup = yield* Effect.promise(() => Promise.resolve(plugin.setup(context2)))
-        if (!cleanup) return
-        yield* Effect.addFinalizer(() => Effect.promise(() => Promise.resolve(cleanup())))
+        yield* Effect.acquireRelease(
+          Effect.promise(() => Promise.resolve(plugin.setup(context2))),
+          (cleanup) => (cleanup ? Effect.promise(() => Promise.resolve(cleanup())) : Effect.void),
+        )
       }),
   })
 }