feat(cli): port ACP to V2 (#37907)

bun.lock

@@ -124,6 +124,7 @@
         "opencode2": "./bin/opencode2.cjs",
       },
       "dependencies": {
+        "@agentclientprotocol/sdk": "0.21.0",
         "@effect/platform-node": "catalog:",
         "@opencode-ai/client": "workspace:*",
         "@opencode-ai/plugin": "workspace:*",
@@ -1159,6 +1160,8 @@
 
     "@adobe/css-tools": ["@adobe/css-tools@4.5.0", "", {}, "sha512-6OzddxPio9UiWTCemp4N8cYLV2ZN1ncRnV1cVGtve7dhPOtRkleRyx32GQCYSwDYgaHU3USMm84tNsvKzRCa1Q=="],
 
+    "@agentclientprotocol/sdk": ["@agentclientprotocol/sdk@0.21.0", "", { "peerDependencies": { "zod": "^3.25.0 || ^4.0.0" } }, "sha512-ONj+Q8qOdNQp5XbH5jnMwzT9IKZJsSN0p0lkceS4GtUtNOPVLpNzSS8gqQdGMKfBvA0ESbkL8BTaSN1Rc9miEw=="],
+
     "@ai-sdk/alibaba": ["@ai-sdk/alibaba@1.0.17", "", { "dependencies": { "@ai-sdk/openai-compatible": "2.0.41", "@ai-sdk/provider": "3.0.8", "@ai-sdk/provider-utils": "4.0.23" }, "peerDependencies": { "zod": "^3.25.76 || ^4.1.8" } }, "sha512-ZbE+U5bWz2JBc5DERLowx5+TKbjGBE93LqKZAWvuEn7HOSQMraxFMZuc0ST335QZJAyfBOzh7m1mPQ+y7EaaoA=="],
 
     "@ai-sdk/amazon-bedrock": ["@ai-sdk/amazon-bedrock@4.0.112", "", { "dependencies": { "@ai-sdk/anthropic": "3.0.81", "@ai-sdk/openai": "3.0.67", "@ai-sdk/provider": "3.0.10", "@ai-sdk/provider-utils": "4.0.27", "@smithy/eventstream-codec": "^4.0.1", "@smithy/util-utf8": "^4.0.0", "aws4fetch": "^1.0.20" }, "peerDependencies": { "zod": "^3.25.76 || ^4.1.8" } }, "sha512-PsSh7a6qW+3kQXPs1kD4wDwuZby0t1PIaB6j/1aMKmPFJ5LxcIcULLMF/bjITLt5o/8lc0t6TXIwG0zlhH7uZw=="],

packages/cli/package.json

@@ -23,6 +23,7 @@
     "typecheck": "tsgo --noEmit"
   },
   "dependencies": {
+    "@agentclientprotocol/sdk": "0.21.0",
     "@effect/platform-node": "catalog:",
     "@opencode-ai/client": "workspace:*",
     "@opencode-ai/plugin": "workspace:*",

packages/cli/src/acp/agent.ts

@@ -0,0 +1,65 @@
+import {
+  RequestError,
+  type Agent,
+  type AgentSideConnection,
+  type AuthenticateRequest,
+  type CancelNotification,
+  type CloseSessionRequest,
+  type ForkSessionRequest,
+  type InitializeRequest,
+  type ListSessionsRequest,
+  type LoadSessionRequest,
+  type NewSessionRequest,
+  type PromptRequest,
+  type ResumeSessionRequest,
+  type SetSessionConfigOptionRequest,
+  type SetSessionModelRequest,
+  type SetSessionModeRequest,
+} from "@agentclientprotocol/sdk"
+import type { OpenCodeClient } from "@opencode-ai/client/promise"
+import { ACPError } from "./error"
+import { ACPService } from "./service"
+
+export function create(client: OpenCodeClient, connection: AgentSideConnection) {
+  const service = ACPService.make({ client, connection })
+  return {
+    initialize: (params: InitializeRequest) => run(service.initialize(params)),
+    authenticate: (params: AuthenticateRequest) => run(service.authenticate(params)),
+    newSession: (params: NewSessionRequest) => run(service.newSession(params)),
+    loadSession: (params: LoadSessionRequest) => run(service.loadSession(params)),
+    listSessions: (params: ListSessionsRequest) => run(service.listSessions(params)),
+    resumeSession: (params: ResumeSessionRequest) => run(service.resumeSession(params)),
+    closeSession: (params: CloseSessionRequest) => run(service.closeSession(params)),
+    unstable_forkSession: (params: ForkSessionRequest) => run(service.forkSession(params)),
+    setSessionConfigOption: (params: SetSessionConfigOptionRequest) => run(service.setSessionConfigOption(params)),
+    setSessionMode: (params: SetSessionModeRequest) => run(service.setSessionMode(params)),
+    unstable_setSessionModel: (params: SetSessionModelRequest) => run(service.setSessionModel(params)),
+    prompt: (params: PromptRequest) => run(service.prompt(params)),
+    cancel: (params: CancelNotification) => run(service.cancel(params)),
+  } satisfies Agent
+}
+
+async function run<A>(promise: Promise<A>) {
+  try {
+    return await promise
+  } catch (error) {
+    if (error instanceof RequestError) throw error
+    if (isACPError(error)) throw ACPError.toRequestError(error)
+    throw ACPError.toRequestError(ACPError.fromUnknown(error))
+  }
+}
+
+function isACPError(error: unknown): error is ACPError.Error {
+  return (
+    error instanceof ACPError.SessionNotFoundError ||
+    error instanceof ACPError.InvalidConfigOptionError ||
+    error instanceof ACPError.InvalidModelError ||
+    error instanceof ACPError.InvalidEffortError ||
+    error instanceof ACPError.InvalidModeError ||
+    error instanceof ACPError.AuthRequiredError ||
+    error instanceof ACPError.UnknownAuthMethodError ||
+    error instanceof ACPError.ServiceFailureError
+  )
+}
+
+export * as ACP from "./agent"

packages/cli/src/acp/config-option.ts

@@ -0,0 +1,133 @@
+import type { SessionConfigOption } from "@agentclientprotocol/sdk"
+
+export const DEFAULT_VARIANT_VALUE = "default"
+
+export type ConfigOptionModel = {
+  id: string
+  name: string
+  variants?: ReadonlyArray<string>
+}
+
+export type ConfigOptionProvider = {
+  id: string
+  name: string
+  models: ReadonlyArray<ConfigOptionModel>
+}
+
+export type ConfigOptionMode = {
+  id: string
+  name: string
+  description?: string
+}
+
+export type ModelSelection = {
+  model: { providerID: string; modelID: string }
+  variant?: string
+}
+
+export function buildConfigOptions(input: {
+  providers: readonly ConfigOptionProvider[]
+  currentModel: ModelSelection["model"]
+  currentVariant?: string
+  modes?: readonly ConfigOptionMode[]
+  currentModeId?: string
+}): SessionConfigOption[] {
+  const variants =
+    input.providers
+      .find((provider) => provider.id === input.currentModel.providerID)
+      ?.models.find((model) => model.id === input.currentModel.modelID)?.variants ?? []
+  const effort =
+    variants.length > 0 ? buildEffortSelectOption({ variants, currentVariant: input.currentVariant }) : undefined
+  return [
+    buildModelSelectOption({ providers: input.providers, currentModel: input.currentModel }),
+    ...(effort ? [effort] : []),
+    ...(input.modes && input.currentModeId
+      ? [buildModeSelectOption({ modes: input.modes, currentModeId: input.currentModeId })]
+      : []),
+  ]
+}
+
+export function buildModelSelectOption(input: {
+  providers: readonly ConfigOptionProvider[]
+  currentModel: ModelSelection["model"]
+}): SessionConfigOption {
+  return {
+    id: "model",
+    name: "Model",
+    category: "model",
+    type: "select",
+    currentValue: `${input.currentModel.providerID}/${input.currentModel.modelID}`,
+    options: input.providers.flatMap((provider) =>
+      provider.models
+        .toSorted((a, b) => a.name.localeCompare(b.name))
+        .map((model) => ({ value: `${provider.id}/${model.id}`, name: `${provider.name}/${model.name}` })),
+    ),
+  }
+}
+
+export function buildEffortSelectOption(input: {
+  variants: readonly string[]
+  currentVariant?: string
+}): SessionConfigOption {
+  return {
+    id: "effort",
+    name: "Effort",
+    description: "Available effort levels for this model",
+    category: "thought_level",
+    type: "select",
+    currentValue: selectVariant(input.currentVariant, input.variants),
+    options: input.variants.map((variant) => ({ value: variant, name: formatVariantName(variant) })),
+  }
+}
+
+export function buildModeSelectOption(input: {
+  modes: readonly ConfigOptionMode[]
+  currentModeId: string
+}): SessionConfigOption {
+  return {
+    id: "mode",
+    name: "Session Mode",
+    category: "mode",
+    type: "select",
+    currentValue: input.currentModeId,
+    options: input.modes.map((mode) => ({
+      value: mode.id,
+      name: mode.name,
+      ...(mode.description ? { description: mode.description } : {}),
+    })),
+  }
+}
+
+export function parseModelSelection(modelId: string, providers: readonly ConfigOptionProvider[]): ModelSelection {
+  const provider = providers.find((item) => modelId.startsWith(`${item.id}/`))
+  if (!provider) {
+    const separator = modelId.indexOf("/")
+    if (separator === -1) return { model: { providerID: modelId, modelID: "" } }
+    return { model: { providerID: modelId.slice(0, separator), modelID: modelId.slice(separator + 1) } }
+  }
+  const modelID = modelId.slice(provider.id.length + 1)
+  if (provider.models.some((model) => model.id === modelID)) return { model: { providerID: provider.id, modelID } }
+  const separator = modelID.lastIndexOf("/")
+  const baseModelID = separator === -1 ? modelID : modelID.slice(0, separator)
+  const variant = separator === -1 ? undefined : modelID.slice(separator + 1)
+  const model = provider.models.find((item) => item.id === baseModelID)
+  if (model && variant && model.variants?.includes(variant)) {
+    return { model: { providerID: provider.id, modelID: baseModelID }, variant }
+  }
+  return { model: { providerID: provider.id, modelID } }
+}
+
+export function formatVariantName(variant: string) {
+  return variant
+    .split(/[_-]/)
+    .map((part) => (part ? part.charAt(0).toUpperCase() + part.slice(1) : part))
+    .join(" ")
+}
+
+function selectVariant(variant: string | undefined, variants: readonly string[]) {
+  if (variant && variants.includes(variant)) return variant
+  if (variants.includes(DEFAULT_VARIANT_VALUE)) return DEFAULT_VARIANT_VALUE
+  return variants[0] ?? DEFAULT_VARIANT_VALUE
+}
+
+export * as ACPConfigOption from "./config-option"

packages/cli/src/acp/content.ts

@@ -0,0 +1,183 @@
+import type { ContentBlock, ContentChunk, ResourceLink } from "@agentclientprotocol/sdk"
+import path from "node:path"
+import { fileURLToPath, pathToFileURL } from "node:url"
+
+export type PromptPart =
+  | { readonly type: "text"; readonly text: string; readonly synthetic?: boolean; readonly ignored?: boolean }
+  | { readonly type: "file"; readonly url: string; readonly filename?: string; readonly mime: string }
+
+export type ReplayPart = PromptPart | { readonly type: "reasoning"; readonly text: string }
+
+export function promptContentToParts(content: readonly ContentBlock[]): PromptPart[] {
+  return content.flatMap(contentBlockToParts)
+}
+
+export function contentBlockToParts(block: ContentBlock): PromptPart[] {
+  switch (block.type) {
+    case "text": {
+      const audience = block.annotations?.audience
+      if (audience?.length === 1 && audience[0] === "assistant") {
+        return [{ type: "text", text: block.text, synthetic: true }]
+      }
+      if (audience?.length === 1 && audience[0] === "user") {
+        return [{ type: "text", text: block.text, ignored: true }]
+      }
+      return [{ type: "text", text: block.text }]
+    }
+    case "image":
+      if (block.data) {
+        return [
+          {
+            type: "file",
+            url: `data:${block.mimeType};base64,${block.data}`,
+            filename: filenameFromUri(block.uri ?? undefined) ?? "image",
+            mime: block.mimeType,
+          },
+        ]
+      }
+      if (block.uri?.startsWith("data:") || block.uri?.startsWith("http://") || block.uri?.startsWith("https://")) {
+        return [
+          {
+            type: "file",
+            url: block.uri,
+            filename: filenameFromUri(block.uri) ?? "image",
+            mime: block.mimeType,
+          },
+        ]
+      }
+      return []
+    case "resource_link":
+      return [resourceLinkToPart(block)]
+    case "resource":
+      if ("text" in block.resource) {
+        try {
+          const parsed = new URL(block.resource.uri)
+          if (parsed.protocol === "file:") {
+            const line = parsed.hash.match(/^#L(\d+)/)?.[1]
+            const decoded = (() => {
+              try {
+                return fileURLToPath(parsed)
+              } catch {
+                return decodeURIComponent(parsed.pathname)
+              }
+            })()
+            const filepath = path.sep === "\\" ? decoded.replace(/\\/g, "/") : decoded
+            return [{ type: "text", text: `[${filepath}${line ? `:${line}` : ""}]\n${block.resource.text}` }]
+          }
+        } catch {}
+        return [{ type: "text", text: `[${block.resource.uri}]\n${block.resource.text}` }]
+      }
+      if (!block.resource.mimeType) return []
+      return [
+        {
+          type: "file",
+          url: block.resource.uri.startsWith("data:")
+            ? block.resource.uri
+            : `data:${block.resource.mimeType};base64,${block.resource.blob}`,
+          filename: filenameFromUri(block.resource.uri) ?? "file",
+          mime: block.resource.mimeType,
+        },
+      ]
+    default:
+      return []
+  }
+}
+
+export function partsToContentChunks(parts: readonly ReplayPart[]): ContentChunk[] {
+  return parts.flatMap((part): ContentChunk[] => {
+    if (part.type === "text") {
+      if (!part.text) return []
+      return [
+        {
+          content: {
+            type: "text",
+            text: part.text,
+            ...(part.synthetic ? { annotations: { audience: ["assistant" as const] } } : {}),
+            ...(!part.synthetic && part.ignored ? { annotations: { audience: ["user" as const] } } : {}),
+          },
+        },
+      ]
+    }
+    if (part.type === "reasoning") {
+      return part.text ? [{ content: { type: "text", text: part.text } }] : []
+    }
+    if (part.url.startsWith("file://")) {
+      return [
+        {
+          content: {
+            type: "resource_link",
+            uri: part.url,
+            name: part.filename ?? "file",
+            mimeType: part.mime,
+          },
+        },
+      ]
+    }
+    if (!part.url.startsWith("data:")) return []
+    const match = /^data:([^;]+);base64,(.*)$/.exec(part.url)
+    if (!match?.[1] || match[2] === undefined) return []
+    const mime = match[1]
+    const data = match[2]
+    if (mime.startsWith("image/")) {
+      return [
+        {
+          content: {
+            type: "image",
+            mimeType: mime,
+            data,
+            uri: pathToFileURL(part.filename ?? "image").href,
+          },
+        },
+      ]
+    }
+    return [
+      {
+        content: {
+          type: "resource",
+          resource:
+            mime.startsWith("text/") || mime === "application/json"
+              ? {
+                  uri: pathToFileURL(part.filename ?? "file").href,
+                  mimeType: mime,
+                  text: Buffer.from(data, "base64").toString("utf8"),
+                }
+              : {
+                  uri: pathToFileURL(part.filename ?? "file").href,
+                  mimeType: mime,
+                  blob: data,
+                },
+        },
+      },
+    ]
+  })
+}
+
+function resourceLinkToPart(link: ResourceLink): PromptPart {
+  if (link.uri.startsWith("file://")) {
+    return {
+      type: "file",
+      url: link.uri,
+      filename: link.name || filenameFromUri(link.uri) || "file",
+      mime: link.mimeType ?? "text/plain",
+    }
+  }
+  if (link.uri.startsWith("zed://") && URL.canParse(link.uri)) {
+    const pathname = new URL(link.uri).searchParams.get("path")
+    if (pathname)
+      return {
+        type: "file",
+        url: pathToFileURL(pathname).href,
+        filename: link.name || path.basename(pathname) || "file",
+        mime: link.mimeType ?? "text/plain",
+      }
+  }
+  return { type: "text", text: link.uri }
+}
+
+function filenameFromUri(uri: string | undefined): string | undefined {
+  if (!uri || uri.startsWith("data:")) return undefined
+  if (URL.canParse(uri)) return path.basename(new URL(uri).pathname) || undefined
+  return path.basename(uri) || undefined
+}
+
+export * as ACPContent from "./content"

packages/cli/src/acp/error.ts

@@ -0,0 +1,86 @@
+import { RequestError } from "@agentclientprotocol/sdk"
+import { Schema } from "effect"
+
+export class SessionNotFoundError extends Schema.TaggedErrorClass<SessionNotFoundError>()("ACPSessionNotFoundError", {
+  sessionId: Schema.String,
+}) {}
+
+export class InvalidConfigOptionError extends Schema.TaggedErrorClass<InvalidConfigOptionError>()(
+  "ACPInvalidConfigOptionError",
+  { configId: Schema.String },
+) {}
+
+export class InvalidModelError extends Schema.TaggedErrorClass<InvalidModelError>()("ACPInvalidModelError", {
+  modelId: Schema.String,
+  providerId: Schema.optional(Schema.String),
+}) {}
+
+export class InvalidEffortError extends Schema.TaggedErrorClass<InvalidEffortError>()("ACPInvalidEffortError", {
+  effort: Schema.String,
+}) {}
+
+export class InvalidModeError extends Schema.TaggedErrorClass<InvalidModeError>()("ACPInvalidModeError", {
+  mode: Schema.String,
+}) {}
+
+export class AuthRequiredError extends Schema.TaggedErrorClass<AuthRequiredError>()("ACPAuthRequiredError", {}) {}
+
+export class UnknownAuthMethodError extends Schema.TaggedErrorClass<UnknownAuthMethodError>()(
+  "ACPUnknownAuthMethodError",
+  { methodId: Schema.String },
+) {}
+
+export class ServiceFailureError extends Schema.TaggedErrorClass<ServiceFailureError>()("ACPServiceFailureError", {
+  safeMessage: Schema.String,
+  service: Schema.optional(Schema.String),
+  errorName: Schema.optional(Schema.String),
+}) {}
+
+export type Error =
+  | SessionNotFoundError
+  | InvalidConfigOptionError
+  | InvalidModelError
+  | InvalidEffortError
+  | InvalidModeError
+  | AuthRequiredError
+  | UnknownAuthMethodError
+  | ServiceFailureError
+
+export function toRequestError(error: Error): RequestError {
+  switch (error._tag) {
+    case "ACPSessionNotFoundError":
+      return RequestError.invalidParams({ sessionId: error.sessionId }, `session not found: ${error.sessionId}`)
+    case "ACPInvalidConfigOptionError":
+      return RequestError.invalidParams({ configId: error.configId }, `unknown config option: ${error.configId}`)
+    case "ACPInvalidModelError":
+      return RequestError.invalidParams(
+        { providerId: error.providerId, modelId: error.modelId },
+        `model not found: ${error.modelId}`,
+      )
+    case "ACPInvalidEffortError":
+      return RequestError.invalidParams({ effort: error.effort }, `effort not found: ${error.effort}`)
+    case "ACPInvalidModeError":
+      return RequestError.invalidParams({ mode: error.mode }, `mode not found: ${error.mode}`)
+    case "ACPAuthRequiredError":
+      return RequestError.authRequired({}, "provider authentication required")
+    case "ACPUnknownAuthMethodError":
+      return RequestError.invalidParams({ methodId: error.methodId }, `unknown auth method: ${error.methodId}`)
+    case "ACPServiceFailureError":
+      return RequestError.internalError(
+        {
+          ...(error.service ? { service: error.service } : {}),
+          ...(error.errorName ? { errorName: error.errorName } : {}),
+        },
+        error.safeMessage,
+      )
+  }
+  const exhaustive: never = error
+  return exhaustive
+}
+
+export function fromUnknown(error: unknown, service?: string) {
+  const errorName = error instanceof Error ? error.name : undefined
+  return new ServiceFailureError({ safeMessage: "Internal service failure", service, errorName })
+}
+
+export * as ACPError from "./error"

packages/cli/src/acp/event.ts

@@ -0,0 +1,441 @@
+import type { AgentSideConnection, PromptResponse } from "@agentclientprotocol/sdk"
+import type {
+  EventSubscribeOutput,
+  OpenCodeClient,
+  SessionMessageAssistant,
+  SessionMessageInfo,
+} from "@opencode-ai/client/promise"
+import { partsToContentChunks, type ReplayPart } from "./content"
+import { ACPError } from "./error"
+import { replyPermission, syncEditedFiles } from "./permission"
+import {
+  completedToolUpdate,
+  errorToolUpdate,
+  pendingToolCall,
+  runningToolUpdate,
+  type ToolContent,
+  type ToolInput,
+} from "./tool"
+
+type Connection = Pick<AgentSideConnection, "sessionUpdate" | "requestPermission"> &
+  Partial<Pick<AgentSideConnection, "writeTextFile">>
+
+export type TurnControl = {
+  cancelled: boolean
+  readonly admission: AbortController
+}
+
+type ToolState = {
+  readonly name: string
+  input: ToolInput
+  structured: Record<string, unknown>
+  content: ToolContent
+}
+
+export type TurnStart =
+  | { readonly type: "input"; readonly id: string }
+  | { readonly type: "skill"; readonly id: string }
+  | { readonly type: "compaction"; readonly id: string }
+
+function emptyToolState(): ToolState {
+  return { name: "tool", input: {}, structured: {}, content: [] }
+}
+
+export async function streamTurn(input: {
+  readonly client: OpenCodeClient
+  readonly connection: Connection
+  readonly sessionID: string
+  readonly cwd: string
+  readonly start: TurnStart
+  readonly userMessageID?: string | null
+  readonly submit: (signal: AbortSignal) => Promise<unknown>
+  readonly control: TurnControl
+}): Promise<PromptResponse> {
+  const streamController = new AbortController()
+  const stream = input.client.event.subscribe({ signal: streamController.signal })[Symbol.asyncIterator]()
+  const connected = await stream.next()
+  if (connected.done) throw new Error("event stream disconnected before prompt admission")
+
+  const control = input.control
+  let started = false
+  let assistantMessageID: string | undefined
+  let finish: SessionMessageAssistant["finish"]
+  let executionError: { readonly type: string; readonly message: string } | undefined
+  const tools = new Map<string, ToolState>()
+
+  const update = (value: Parameters<Connection["sessionUpdate"]>[0]["update"]) =>
+    input.connection.sessionUpdate({ sessionId: input.sessionID, update: value })
+
+  const consume = async () => {
+    while (!streamController.signal.aborted) {
+      const next = await stream.next()
+      if (next.done) throw new Error("event stream disconnected during prompt execution")
+      const event = next.value
+      if (event.type === "permission.v2.asked" && event.data.sessionID === input.sessionID) {
+        const tool = event.data.source?.callID ? tools.get(event.data.source.callID) : undefined
+        await replyPermission({
+          client: input.client,
+          connection: input.connection,
+          event,
+          sessionID: input.sessionID,
+          cwd: input.cwd,
+          tool,
+        })
+        continue
+      }
+      if (event.type === "form.created" && event.data.form.sessionID === input.sessionID) {
+        await input.client.form
+          .cancel({ sessionID: input.sessionID, formID: event.data.form.id })
+          .catch(() => input.client.session.interrupt({ sessionID: input.sessionID }).catch(() => {}))
+        continue
+      }
+      if (!("sessionID" in event.data) || event.data.sessionID !== input.sessionID) continue
+      if (matchesStart(event, input.start)) {
+        started = true
+        continue
+      }
+      if (!started) continue
+
+      if (event.type === "session.step.started") {
+        assistantMessageID = event.data.assistantMessageID
+        continue
+      }
+      if (event.type === "session.text.delta") {
+        assistantMessageID = event.data.assistantMessageID
+        await update({
+          sessionUpdate: "agent_message_chunk",
+          messageId: event.data.assistantMessageID,
+          content: { type: "text", text: event.data.delta },
+        })
+        continue
+      }
+      if (event.type === "session.reasoning.delta") {
+        assistantMessageID = event.data.assistantMessageID
+        await update({
+          sessionUpdate: "agent_thought_chunk",
+          messageId: event.data.assistantMessageID,
+          content: { type: "text", text: event.data.delta },
+        })
+        continue
+      }
+      if (event.type === "session.tool.input.started") {
+        assistantMessageID = event.data.assistantMessageID
+        tools.set(event.data.callID, { name: event.data.name, input: {}, structured: {}, content: [] })
+        await update({
+          sessionUpdate: "tool_call",
+          ...pendingToolCall({
+            toolCallId: event.data.callID,
+            toolName: event.data.name,
+            state: { input: {} },
+            cwd: input.cwd,
+          }),
+        })
+        continue
+      }
+      if (event.type === "session.tool.called") {
+        assistantMessageID = event.data.assistantMessageID
+        const current = tools.get(event.data.callID) ?? emptyToolState()
+        current.input = event.data.input
+        tools.set(event.data.callID, current)
+        await update({
+          sessionUpdate: "tool_call_update",
+          ...runningToolUpdate({
+            toolCallId: event.data.callID,
+            toolName: current.name,
+            state: { input: current.input },
+            cwd: input.cwd,
+          }),
+        })
+        continue
+      }
+      if (event.type === "session.tool.progress") {
+        const current = tools.get(event.data.callID)
+        if (!current) continue
+        current.structured = event.data.structured
+        current.content = event.data.content
+        await update({
+          sessionUpdate: "tool_call_update",
+          ...runningToolUpdate({
+            toolCallId: event.data.callID,
+            toolName: current.name,
+            state: { input: current.input },
+            content: current.content,
+            cwd: input.cwd,
+          }),
+        })
+        continue
+      }
+      if (event.type === "session.tool.success") {
+        const current = tools.get(event.data.callID) ?? emptyToolState()
+        tools.delete(event.data.callID)
+        await syncEditedFiles({
+          connection: input.connection,
+          sessionID: input.sessionID,
+          cwd: input.cwd,
+          toolName: current.name,
+          toolInput: current.input,
+          structured: event.data.structured,
+        }).catch(() => {})
+        await update({
+          sessionUpdate: "tool_call_update",
+          ...completedToolUpdate({
+            toolCallId: event.data.callID,
+            toolName: current.name,
+            input: current.input,
+            structured: event.data.structured,
+            content: event.data.content,
+            result: event.data.result,
+          }),
+        })
+        continue
+      }
+      if (event.type === "session.tool.failed") {
+        const current = tools.get(event.data.callID) ?? emptyToolState()
+        tools.delete(event.data.callID)
+        await update({
+          sessionUpdate: "tool_call_update",
+          ...errorToolUpdate({
+            toolCallId: event.data.callID,
+            toolName: current.name,
+            input: current.input,
+            structured: current.structured,
+            content: current.content,
+            error: event.data.error.message,
+            cwd: input.cwd,
+          }),
+        })
+        continue
+      }
+      if (event.type === "session.step.ended") {
+        assistantMessageID = event.data.assistantMessageID
+        finish = event.data.finish
+        continue
+      }
+      if (event.type === "session.execution.succeeded") return "succeeded" as const
+      if (event.type === "session.execution.interrupted") return "interrupted" as const
+      if (event.type === "session.execution.failed") {
+        executionError = event.data.error
+        return "failed" as const
+      }
+    }
+    return "interrupted" as const
+  }
+
+  const completed = consume()
+  try {
+    await input.submit(control.admission.signal).catch((error) => {
+      if (!control.cancelled) throw error
+    })
+    if (control.cancelled) {
+      await input.client.session.interrupt({ sessionID: input.sessionID }).catch(() => {})
+      if (!started) {
+        streamController.abort()
+        await completed.catch(() => {})
+        return response(undefined, undefined, "interrupted", true, undefined, input.userMessageID)
+      }
+    }
+    const terminal = await completed
+    const assistant = assistantMessageID
+      ? await input.client.session
+          .message({ sessionID: input.sessionID, messageID: assistantMessageID })
+          .catch(() => undefined)
+      : undefined
+    return response(
+      assistant?.type === "assistant" ? assistant : undefined,
+      executionError,
+      terminal,
+      control.cancelled,
+      finish,
+      input.userMessageID,
+    )
+  } catch (error) {
+    streamController.abort()
+    await completed.catch(() => {})
+    throw error
+  } finally {
+    streamController.abort()
+    await stream.return?.(undefined).catch(() => {})
+  }
+}
+
+export async function replayMessages(
+  connection: Pick<AgentSideConnection, "sessionUpdate">,
+  sessionID: string,
+  cwd: string,
+  messages: readonly SessionMessageInfo[],
+) {
+  for (const message of messages) await replayMessage(connection, sessionID, cwd, message).catch(() => {})
+}
+
+async function replayMessage(
+  connection: Pick<AgentSideConnection, "sessionUpdate">,
+  sessionID: string,
+  cwd: string,
+  message: SessionMessageInfo,
+) {
+  if (message.type === "user") {
+    await connection.sessionUpdate({
+      sessionId: sessionID,
+      update: {
+        sessionUpdate: "user_message_chunk",
+        messageId: message.id,
+        content: { type: "text", text: message.text },
+      },
+    })
+    const files: ReplayPart[] = (message.files ?? []).map((file) => ({
+      type: "file",
+      url: file.source.type === "uri" ? file.source.uri : `data:${file.mime};base64,${file.data}`,
+      filename: file.name,
+      mime: file.mime,
+    }))
+    for (const chunk of partsToContentChunks(files)) {
+      await connection.sessionUpdate({
+        sessionId: sessionID,
+        update: { sessionUpdate: "user_message_chunk", messageId: message.id, ...chunk },
+      })
+    }
+    return
+  }
+  if (message.type !== "assistant") return
+  for (const part of message.content) {
+    if (part.type === "text") {
+      await connection.sessionUpdate({
+        sessionId: sessionID,
+        update: {
+          sessionUpdate: "agent_message_chunk",
+          messageId: message.id,
+          content: { type: "text", text: part.text },
+        },
+      })
+      continue
+    }
+    if (part.type === "reasoning") {
+      await connection.sessionUpdate({
+        sessionId: sessionID,
+        update: {
+          sessionUpdate: "agent_thought_chunk",
+          messageId: message.id,
+          content: { type: "text", text: part.text },
+        },
+      })
+      continue
+    }
+    await connection.sessionUpdate({
+      sessionId: sessionID,
+      update: {
+        sessionUpdate: "tool_call",
+        ...pendingToolCall({
+          toolCallId: part.id,
+          toolName: part.name,
+          state: { input: part.state.status === "streaming" ? {} : part.state.input },
+          cwd,
+        }),
+      },
+    })
+    switch (part.state.status) {
+      case "completed":
+        await connection.sessionUpdate({
+          sessionId: sessionID,
+          update: {
+            sessionUpdate: "tool_call_update",
+            ...completedToolUpdate({
+              toolCallId: part.id,
+              toolName: part.name,
+              input: part.state.input,
+              structured: part.state.structured,
+              content: part.state.content,
+              result: part.state.result,
+            }),
+          },
+        })
+        break
+      case "running":
+        await connection.sessionUpdate({
+          sessionId: sessionID,
+          update: {
+            sessionUpdate: "tool_call_update",
+            ...runningToolUpdate({
+              toolCallId: part.id,
+              toolName: part.name,
+              state: { input: part.state.input },
+              content: part.state.content,
+              cwd,
+            }),
+          },
+        })
+        break
+      case "error":
+        await connection.sessionUpdate({
+          sessionId: sessionID,
+          update: {
+            sessionUpdate: "tool_call_update",
+            ...errorToolUpdate({
+              toolCallId: part.id,
+              toolName: part.name,
+              input: part.state.input,
+              structured: part.state.structured,
+              content: part.state.content,
+              error: part.state.error.message,
+              cwd,
+            }),
+          },
+        })
+        break
+      case "streaming":
+        break
+    }
+  }
+}
+
+function matchesStart(event: EventSubscribeOutput, start: TurnStart) {
+  if (start.type === "input") return event.type === "session.input.promoted" && event.data.inputID === start.id
+  if (start.type === "compaction")
+    return event.type === "session.compaction.admitted" && event.data.inputID === start.id
+  return event.type === "session.skill.activated" && event.id === start.id.replace(/^msg_/, "evt_")
+}
+
+function response(
+  assistant: SessionMessageAssistant | undefined,
+  executionError: { readonly type: string; readonly message: string } | undefined,
+  terminal: "succeeded" | "failed" | "interrupted",
+  cancelled: boolean,
+  finish: SessionMessageAssistant["finish"],
+  messageID: string | null | undefined,
+): PromptResponse {
+  const error = assistant?.error ?? executionError
+  if (error?.type === "provider.auth") throw new ACPError.AuthRequiredError()
+  if (error && error.type !== "aborted" && error.type !== "provider.content-filter") {
+    throw new ACPError.ServiceFailureError({
+      safeMessage: error.message || "OpenCode prompt failed",
+      service: "session",
+      errorName: error.type,
+    })
+  }
+  const tokens = assistant?.tokens
+  const usage = tokens
+    ? {
+        inputTokens: tokens.input,
+        outputTokens: tokens.output,
+        totalTokens: tokens.input + tokens.output + tokens.reasoning + tokens.cache.read + tokens.cache.write,
+        ...(tokens.reasoning > 0 ? { thoughtTokens: tokens.reasoning } : {}),
+        ...(tokens.cache.read > 0 ? { cachedReadTokens: tokens.cache.read } : {}),
+        ...(tokens.cache.write > 0 ? { cachedWriteTokens: tokens.cache.write } : {}),
+      }
+    : undefined
+  const stopReason = resolveStopReason({ terminal, cancelled, finish, error: error?.type })
+  return { stopReason, ...(usage ? { usage } : {}), ...(messageID ? { userMessageId: messageID } : {}), _meta: {} }
+}
+
+function resolveStopReason(input: {
+  readonly terminal: "succeeded" | "failed" | "interrupted"
+  readonly cancelled: boolean
+  readonly finish: SessionMessageAssistant["finish"]
+  readonly error?: string
+}): PromptResponse["stopReason"] {
+  if (input.cancelled || input.terminal === "interrupted" || input.error === "aborted") return "cancelled"
+  if (input.finish === "length") return "max_tokens"
+  if (input.finish === "content-filter" || input.error === "provider.content-filter") return "refusal"
+  return "end_turn"
+}
+
+export * as ACPEvent from "./event"

packages/cli/src/acp/permission.ts

@@ -0,0 +1,179 @@
+import type { AgentSideConnection, PermissionOption, ToolCallContent, ToolCallLocation } from "@agentclientprotocol/sdk"
+import type { EventSubscribeOutput, OpenCodeClient } from "@opencode-ai/client/promise"
+import { Patch } from "@opencode-ai/util/patch"
+import { Result } from "effect"
+import { isAbsolute, resolve } from "node:path"
+import { pendingToolCall, stringValue, toLocations, toToolKind, type ToolInput } from "./tool"
+
+type PermissionEvent = Extract<EventSubscribeOutput, { type: "permission.v2.asked" }>
+type Connection = Pick<AgentSideConnection, "requestPermission"> & Partial<Pick<AgentSideConnection, "writeTextFile">>
+type Tool = { readonly name: string; readonly input: ToolInput }
+
+const options: PermissionOption[] = [
+  { optionId: "once", kind: "allow_once", name: "Allow once" },
+  { optionId: "always", kind: "allow_always", name: "Always allow" },
+  { optionId: "reject", kind: "reject_once", name: "Reject" },
+]
+
+export async function replyPermission(input: {
+  readonly client: OpenCodeClient
+  readonly connection: Connection
+  readonly event: PermissionEvent
+  readonly sessionID: string
+  readonly cwd: string
+  readonly tool?: Tool
+}) {
+  const toolName = input.tool?.name ?? input.event.data.action
+  const toolInput = { ...input.event.data.metadata, ...input.tool?.input }
+  const previews = await permissionPreviews(toolName, toolInput, input.cwd)
+  const result = await input.connection
+    .requestPermission({
+      sessionId: input.sessionID,
+      toolCall: {
+        ...pendingToolCall({
+          toolCallId: input.event.data.source?.callID ?? input.event.data.id,
+          toolName,
+          state: { input: toolInput, title: permissionTitle(toolName, toolInput, previews) },
+          cwd: input.cwd,
+        }),
+        locations: permissionLocations(toolName, toolInput, input.event.data.resources, input.cwd, previews),
+        ...(previews.length > 0 ? { content: previews } : {}),
+      },
+      options,
+    })
+    .catch(() => undefined)
+  const selected = result?.outcome.outcome === "selected" ? result.outcome.optionId : undefined
+  const reply = selected === "once" || selected === "always" ? selected : "reject"
+  await input.client.permission.reply({
+    sessionID: input.sessionID,
+    requestID: input.event.data.id,
+    reply,
+  })
+}
+
+export async function syncEditedFiles(input: {
+  readonly connection: Partial<Pick<AgentSideConnection, "writeTextFile">>
+  readonly sessionID: string
+  readonly cwd: string
+  readonly toolName: string
+  readonly toolInput: ToolInput
+  readonly structured: Readonly<Record<string, unknown>>
+}) {
+  if (!input.connection.writeTextFile || toToolKind(input.toolName) !== "edit") return
+  const files = Array.isArray(input.structured.files)
+    ? input.structured.files.flatMap((file): string[] => {
+        if (!file || typeof file !== "object") return []
+        const path = Reflect.get(file, "file")
+        return typeof path === "string" ? [path] : []
+      })
+    : []
+  const path = filePath(input.toolInput)
+  const paths = [...new Set([...files, ...(path ? [path] : [])])]
+  await Promise.all(
+    paths.map(async (path) => {
+      const target = resolvePath(path, input.cwd)
+      const file = Bun.file(target)
+      if (!(await file.exists())) return
+      await input.connection.writeTextFile?.({ sessionId: input.sessionID, path: target, content: await file.text() })
+    }),
+  )
+}
+
+async function permissionPreviews(toolName: string, input: ToolInput, cwd: string): Promise<ToolCallContent[]> {
+  const tool = toolName.toLocaleLowerCase()
+  if (tool === "patch" || tool === "apply_patch") return patchPreviews(input, cwd)
+  const path = filePath(input)
+  if (!path) return []
+  const oldText = await readText(path, cwd)
+  if (tool === "write") {
+    const content = stringValue(input.content)
+    return content === undefined ? [] : [{ type: "diff", path, oldText, newText: content }]
+  }
+  if (tool !== "edit") return []
+  const oldString = stringValue(input.oldString)
+  const newString = stringValue(input.newString)
+  if (oldString === undefined || newString === undefined) return []
+  const newText =
+    input.replaceAll === true ? oldText.replaceAll(oldString, newString) : oldText.replace(oldString, newString)
+  return [{ type: "diff", path, oldText, newText }]
+}
+
+async function patchPreviews(input: ToolInput, cwd: string): Promise<ToolCallContent[]> {
+  const patchText = stringValue(input.patchText)
+  if (!patchText) return []
+  try {
+    const parsed = Patch.parse(patchText)
+    if (Result.isFailure(parsed)) return []
+    return await Promise.all(
+      parsed.success.map(async (hunk): Promise<ToolCallContent> => {
+        const oldText = hunk.type === "add" ? "" : await readText(hunk.path, cwd)
+        if (hunk.type === "add") {
+          const newText = hunk.contents.endsWith("\n") || hunk.contents === "" ? hunk.contents : `${hunk.contents}\n`
+          return { type: "diff", path: hunk.path, oldText, newText }
+        }
+        if (hunk.type === "delete") return { type: "diff", path: hunk.path, oldText, newText: "" }
+        return {
+          type: "diff",
+          path: hunk.movePath ?? hunk.path,
+          oldText,
+          newText: Patch.derive(hunk.path, hunk.chunks, oldText).content,
+        }
+      }),
+    )
+  } catch {
+    return []
+  }
+}
+
+function permissionTitle(toolName: string, input: ToolInput, previews: ReadonlyArray<ToolCallContent>) {
+  if (previews.length > 1) return `${previews.length} files`
+  switch (toolName.toLocaleLowerCase()) {
+    case "external_directory":
+      return stringValue(input.description) ?? stringValue(input.command) ?? stringValue(input.parentDir)
+    case "webfetch":
+      return stringValue(input.url)
+    case "websearch":
+      return stringValue(input.query)
+    case "grep":
+    case "glob":
+      return stringValue(input.pattern)
+    case "read":
+    case "edit":
+    case "write":
+    case "patch":
+    case "apply_patch":
+      return filePath(input) ?? (previews[0]?.type === "diff" ? previews[0].path : undefined)
+    default:
+      return undefined
+  }
+}
+
+function permissionLocations(
+  toolName: string,
+  input: ToolInput,
+  resources: ReadonlyArray<string>,
+  cwd: string,
+  previews: ReadonlyArray<ToolCallContent>,
+): ToolCallLocation[] {
+  const paths = previews.flatMap((preview) => (preview.type === "diff" ? [preview.path] : []))
+  if (paths.length > 0) return [...new Set(paths)].map((path) => ({ path }))
+  const locations = toLocations(toolName, input, cwd)
+  if (locations.length > 0) return locations
+  return resources.filter((resource) => resource !== "*").map((path) => ({ path }))
+}
+
+function readText(path: string, cwd: string) {
+  return Bun.file(resolvePath(path, cwd))
+    .text()
+    .catch(() => "")
+}
+
+function filePath(input: ToolInput) {
+  return stringValue(input.path) ?? stringValue(input.filePath) ?? stringValue(input.filepath)
+}
+
+function resolvePath(path: string, cwd: string) {
+  return isAbsolute(path) ? path : resolve(cwd, path)
+}
+
+export * as ACPPermission from "./permission"

packages/cli/src/acp/service.ts

@@ -0,0 +1,531 @@
+import {
+  isSessionNotFoundError,
+  type CommandInfo,
+  type ModelInfo,
+  type ModelRef,
+  type OpenCodeClient,
+  type SessionInfo,
+  type SessionMessageInfo,
+  type SkillInfo,
+} from "@opencode-ai/client/promise"
+import type {
+  AgentSideConnection,
+  AuthenticateRequest,
+  AuthenticateResponse,
+  AuthMethod,
+  CancelNotification,
+  CloseSessionRequest,
+  CloseSessionResponse,
+  ForkSessionRequest,
+  ForkSessionResponse,
+  InitializeRequest,
+  InitializeResponse,
+  ListSessionsRequest,
+  ListSessionsResponse,
+  LoadSessionRequest,
+  LoadSessionResponse,
+  McpServer,
+  NewSessionRequest,
+  NewSessionResponse,
+  PromptRequest,
+  PromptResponse,
+  ResumeSessionRequest,
+  ResumeSessionResponse,
+  SetSessionConfigOptionRequest,
+  SetSessionConfigOptionResponse,
+  SetSessionModelRequest,
+  SetSessionModelResponse,
+  SetSessionModeRequest,
+  SetSessionModeResponse,
+} from "@agentclientprotocol/sdk"
+import { InstallationVersion } from "@opencode-ai/util/installation/version"
+import { SessionMessage } from "@opencode-ai/schema/session-message"
+import { buildConfigOptions, parseModelSelection, type ConfigOptionProvider } from "./config-option"
+import { promptContentToParts } from "./content"
+import { replayMessages, streamTurn, type TurnControl, type TurnStart } from "./event"
+import { ACPError } from "./error"
+
+export const AuthMethodID = "opencode-login"
+
+type Connection = Pick<AgentSideConnection, "sessionUpdate" | "requestPermission">
+
+type Catalog = {
+  readonly providers: ConfigOptionProvider[]
+  readonly models: ModelInfo[]
+  readonly defaultModel: ModelRef
+  readonly modes: Array<{ id: string; name: string; description?: string }>
+  readonly defaultModeID: string
+  readonly commands: CommandInfo[]
+  readonly skills: SkillInfo[]
+}
+
+type Attached = {
+  readonly id: string
+  readonly cwd: string
+  catalog: Catalog
+  model: ModelRef
+  modeID: string
+}
+
+type PreparedPrompt = {
+  readonly start: TurnStart
+  readonly text: string
+  readonly files: Array<{ readonly uri: string; readonly name?: string }>
+  readonly synthetic: ReadonlyArray<string>
+  readonly slash?: { readonly name: string; readonly args: string }
+  readonly command?: CommandInfo
+  readonly skill?: SkillInfo
+}
+
+export interface Interface {
+  initialize(input: InitializeRequest): Promise<InitializeResponse>
+  authenticate(input: AuthenticateRequest): Promise<AuthenticateResponse>
+  newSession(input: NewSessionRequest): Promise<NewSessionResponse>
+  loadSession(input: LoadSessionRequest): Promise<LoadSessionResponse>
+  listSessions(input: ListSessionsRequest): Promise<ListSessionsResponse>
+  resumeSession(input: ResumeSessionRequest): Promise<ResumeSessionResponse>
+  closeSession(input: CloseSessionRequest): Promise<CloseSessionResponse>
+  forkSession(input: ForkSessionRequest): Promise<ForkSessionResponse>
+  setSessionConfigOption(input: SetSessionConfigOptionRequest): Promise<SetSessionConfigOptionResponse>
+  setSessionMode(input: SetSessionModeRequest): Promise<SetSessionModeResponse>
+  setSessionModel(input: SetSessionModelRequest): Promise<SetSessionModelResponse>
+  prompt(input: PromptRequest): Promise<PromptResponse>
+  cancel(input: CancelNotification): Promise<void>
+}
+
+export function make(input: { readonly client: OpenCodeClient; readonly connection: Connection }): Interface {
+  const sessions = new Map<string, Attached>()
+  const catalogs = new Map<string, Promise<Catalog>>()
+  const registeredMcp = new Map<string, Set<string>>()
+  const active = new Map<string, TurnControl>()
+
+  const catalog = (cwd: string) => {
+    const cached = catalogs.get(cwd)
+    if (cached) return cached
+    const loaded = loadCatalog(input.client, cwd).catch((error) => {
+      catalogs.delete(cwd)
+      throw error
+    })
+    catalogs.set(cwd, loaded)
+    return loaded
+  }
+
+  const requireSession = async (sessionID: string) => {
+    const current = sessions.get(sessionID)
+    if (current) return current
+    throw new ACPError.SessionNotFoundError({ sessionId: sessionID })
+  }
+
+  const attach = async (session: SessionInfo, cwd: string, mcpServers: readonly McpServer[]) => {
+    const currentCatalog = await catalog(cwd)
+    const state: Attached = {
+      id: session.id,
+      cwd,
+      catalog: currentCatalog,
+      model: session.model ?? currentCatalog.defaultModel,
+      modeID: session.agent ?? currentCatalog.defaultModeID,
+    }
+    sessions.set(session.id, state)
+    await registerMcpServers(input.client, registeredMcp, state, mcpServers)
+    await input.connection.sessionUpdate({
+      sessionId: state.id,
+      update: {
+        sessionUpdate: "available_commands_update",
+        availableCommands: [
+          ...state.catalog.commands,
+          ...state.catalog.skills.filter(
+            (skill) => !state.catalog.commands.some((command) => command.name === skill.name),
+          ),
+        ].map((command) => ({ name: command.name, description: command.description ?? "" })),
+      },
+    })
+    return state
+  }
+
+  const replay = async (state: Attached) => {
+    await replayMessages(input.connection, state.id, state.cwd, await messages(input.client, state.id))
+  }
+
+  const configOptions = (state: Attached) =>
+    buildConfigOptions({
+      providers: state.catalog.providers,
+      currentModel: { providerID: state.model.providerID, modelID: state.model.id },
+      currentVariant: state.model.variant,
+      modes: state.catalog.modes,
+      currentModeId: state.modeID,
+    })
+
+  return {
+    initialize: async (params) => {
+      const authMethod: AuthMethod = {
+        description: "Run `opencode auth login` in the terminal",
+        name: "Login with opencode",
+        id: AuthMethodID,
+      }
+      if (params.clientCapabilities?._meta?.["terminal-auth"] === true) {
+        authMethod._meta = {
+          "terminal-auth": { command: "opencode", args: ["auth", "login"], label: "OpenCode Login" },
+        }
+      }
+      return {
+        protocolVersion: 1,
+        agentCapabilities: {
+          loadSession: true,
+          mcpCapabilities: { http: true, sse: false },
+          promptCapabilities: { embeddedContext: true, image: true },
+          sessionCapabilities: { close: {}, fork: {}, list: {}, resume: {} },
+        },
+        authMethods: [authMethod],
+        agentInfo: { name: "OpenCode", version: InstallationVersion },
+      }
+    },
+    authenticate: async (params) => {
+      if (params.methodId !== AuthMethodID) throw new ACPError.UnknownAuthMethodError({ methodId: params.methodId })
+      return {}
+    },
+    newSession: async (params) => {
+      const currentCatalog = await catalog(params.cwd)
+      const created = await input.client.session.create({
+        location: { directory: params.cwd },
+        agent: currentCatalog.defaultModeID,
+        model: currentCatalog.defaultModel,
+      })
+      const state = await attach(created, params.cwd, params.mcpServers)
+      return { sessionId: state.id, configOptions: configOptions(state) }
+    },
+    loadSession: async (params) => {
+      const session = await getSession(input.client, params.sessionId)
+      const state = await attach(session, session.location.directory, params.mcpServers)
+      await replay(state)
+      return { configOptions: configOptions(state) }
+    },
+    listSessions: async (params) => {
+      const page = await input.client.session.list({
+        ...(params.cwd ? { directory: params.cwd } : {}),
+        order: "desc",
+        limit: 100,
+        ...(params.cursor ? { cursor: params.cursor } : {}),
+      })
+      return {
+        sessions: page.data.map((session) => ({
+          sessionId: session.id,
+          cwd: session.location.directory,
+          title: session.title,
+          updatedAt: new Date(session.time.updated).toISOString(),
+        })),
+        ...(page.cursor.next ? { nextCursor: page.cursor.next } : {}),
+      }
+    },
+    resumeSession: async (params) => {
+      const session = await getSession(input.client, params.sessionId)
+      const state = await attach(session, session.location.directory, params.mcpServers ?? [])
+      return { configOptions: configOptions(state) }
+    },
+    closeSession: async (params) => {
+      sessions.delete(params.sessionId)
+      registeredMcp.delete(params.sessionId)
+      const turn = active.get(params.sessionId)
+      if (turn) {
+        turn.cancelled = true
+        turn.admission.abort()
+      }
+      await input.client.session.interrupt({ sessionID: params.sessionId }).catch(() => {})
+      return {}
+    },
+    forkSession: async (params) => {
+      const forked = await input.client.session.fork({ sessionID: params.sessionId })
+      const state = await attach(forked, forked.location.directory, params.mcpServers ?? [])
+      await replay(state)
+      return { sessionId: state.id, configOptions: configOptions(state) }
+    },
+    setSessionConfigOption: async (params) => {
+      const state = await requireSession(params.sessionId)
+      if (typeof params.value !== "string") throw new ACPError.InvalidConfigOptionError({ configId: params.configId })
+      switch (params.configId) {
+        case "model": {
+          const selected = requireModel(state.catalog, params.value)
+          state.model = selected
+          await input.client.session.switchModel({ sessionID: state.id, model: selected })
+          break
+        }
+        case "effort": {
+          const model = state.catalog.models.find(
+            (item) => item.providerID === state.model.providerID && item.id === state.model.id,
+          )
+          if (!model?.variants.some((variant) => variant.id === params.value))
+            throw new ACPError.InvalidEffortError({ effort: params.value })
+          state.model = { ...state.model, variant: params.value }
+          await input.client.session.switchModel({ sessionID: state.id, model: state.model })
+          break
+        }
+        case "mode":
+          await selectMode(input.client, state, params.value)
+          break
+        default:
+          throw new ACPError.InvalidConfigOptionError({ configId: params.configId })
+      }
+      return { configOptions: configOptions(state) }
+    },
+    setSessionMode: async (params) => {
+      await selectMode(input.client, await requireSession(params.sessionId), params.modeId)
+      return {}
+    },
+    setSessionModel: async (params) => {
+      const state = await requireSession(params.sessionId)
+      const selected = requireModel(state.catalog, params.modelId)
+      state.model = selected
+      await input.client.session.switchModel({ sessionID: state.id, model: selected })
+      return {}
+    },
+    prompt: async (params) => {
+      const state = await requireSession(params.sessionId)
+      if (active.has(state.id)) {
+        throw new ACPError.ServiceFailureError({
+          safeMessage: `Session already has an active ACP prompt: ${state.id}`,
+          service: "session",
+        })
+      }
+      const messageID = SessionMessage.ID.create()
+      const prepared = preparePrompt(state.catalog, params.prompt, messageID)
+      const control: TurnControl = { cancelled: false, admission: new AbortController() }
+      active.set(state.id, control)
+      const response = await streamTurn({
+        client: input.client,
+        connection: input.connection,
+        sessionID: state.id,
+        cwd: state.cwd,
+        start: prepared.start,
+        userMessageID: params.messageId,
+        control,
+        submit: (signal) => submitPrompt(input.client, state, prepared, signal),
+      }).finally(() => {
+        if (active.get(state.id) === control) active.delete(state.id)
+      })
+      await sendUsageUpdate(input.client, input.connection, state, response.usage?.totalTokens).catch(() => {})
+      return response
+    },
+    cancel: async (params) => {
+      const current = active.get(params.sessionId)
+      if (current) {
+        current.cancelled = true
+        current.admission.abort()
+      }
+      await input.client.session.interrupt({ sessionID: params.sessionId }).catch(() => {})
+    },
+  }
+}
+
+function preparePrompt(catalog: Catalog, prompt: PromptRequest["prompt"], messageID: string): PreparedPrompt {
+  const parts = promptContentToParts(prompt)
+  const visible = parts.filter((part) => part.type !== "text" || (!part.synthetic && !part.ignored))
+  const synthetic = parts.flatMap((part) => (part.type === "text" && part.synthetic ? [part.text] : []))
+  const text = visible.flatMap((part) => (part.type === "text" ? [part.text] : [])).join("\n")
+  const files = visible.flatMap((part) => (part.type === "file" ? [{ uri: part.url, name: part.filename }] : []))
+  const slash = detectSlashCommand(text)
+  const command = slash ? catalog.commands.find((item) => item.name === slash.name) : undefined
+  const skill = slash ? catalog.skills.find((item) => item.name === slash.name) : undefined
+  const start = turnStart(messageID, slash, skill)
+  return { start, text, files, synthetic, slash, command, skill }
+}
+
+async function submitPrompt(client: OpenCodeClient, session: Attached, prompt: PreparedPrompt, signal: AbortSignal) {
+  if (prompt.synthetic.length > 0) {
+    await client.session.synthetic({
+      sessionID: session.id,
+      text: prompt.synthetic.join("\n\n"),
+      description: "ACP embedded context",
+      delivery: "steer",
+      resume: false,
+    })
+  }
+  if (prompt.start.type === "compaction") return client.session.compact({ sessionID: session.id, id: prompt.start.id })
+  if (prompt.skill) return client.session.skill({ sessionID: session.id, id: prompt.start.id, skill: prompt.skill.id })
+  if (prompt.command) {
+    return client.session.command(
+      {
+        sessionID: session.id,
+        id: prompt.start.id,
+        command: prompt.command.name,
+        arguments: prompt.slash?.args,
+        files: prompt.files,
+        delivery: "steer",
+      },
+      { signal },
+    )
+  }
+  return client.session.prompt(
+    { sessionID: session.id, id: prompt.start.id, text: prompt.text, files: prompt.files, delivery: "steer" },
+    { signal },
+  )
+}
+
+function turnStart(messageID: string, slash: PreparedPrompt["slash"], skill: SkillInfo | undefined): TurnStart {
+  if (slash?.name === "compact") return { type: "compaction", id: messageID }
+  if (skill) return { type: "skill", id: messageID }
+  return { type: "input", id: messageID }
+}
+
+async function loadCatalog(client: OpenCodeClient, cwd: string): Promise<Catalog> {
+  const location = { directory: cwd }
+  // Location plugins initialize asynchronously, so the first ACP request may observe an empty catalog.
+  const deadline = Date.now() + 5_000
+  let missing = "No models are available"
+  while (Date.now() < deadline) {
+    const [modelResult, defaultResult, agentResult, commandResult, skillResult] = await Promise.all([
+      client.model.list({ location }),
+      client.model.default({ location }),
+      client.agent.list({ location }),
+      client.command.list({ location }),
+      client.skill.list({ location }),
+    ])
+    const models = modelResult.data.filter((model) => model.enabled)
+    const defaultModel = defaultResult.data ?? models[0]
+    const agents = agentResult.data.filter((agent) => agent.mode !== "subagent" && !agent.hidden)
+    const defaultAgent = agents.find((agent) => agent.mode === "primary") ?? agents[0]
+    if (defaultModel && defaultAgent) {
+      return {
+        providers: providers(models),
+        models,
+        defaultModel: {
+          providerID: defaultModel.providerID,
+          id: defaultModel.id,
+          variant:
+            defaultModel.variants.find((variant) => variant.id === "default")?.id ?? defaultModel.variants[0]?.id,
+        },
+        modes: agents.map((agent) => ({ id: agent.id, name: agent.name, description: agent.description })),
+        defaultModeID: defaultAgent.id,
+        commands: commandResult.data,
+        skills: skillResult.data.filter((skill) => skill.slash !== false),
+      }
+    }
+    missing = defaultModel ? "No primary agents are available" : "No models are available"
+    await Bun.sleep(25)
+  }
+  throw new Error(missing)
+}
+
+function providers(models: readonly ModelInfo[]): ConfigOptionProvider[] {
+  return Array.from(new Set(models.map((model) => model.providerID)))
+    .toSorted()
+    .map((providerID) => ({
+      id: providerID,
+      name: providerID,
+      models: models
+        .filter((model) => model.providerID === providerID)
+        .map((model) => ({ id: model.id, name: model.name, variants: model.variants.map((variant) => variant.id) })),
+    }))
+}
+
+function requireModel(catalog: Catalog, modelID: string): ModelRef {
+  const selected = parseModelSelection(modelID, catalog.providers)
+  const model = catalog.models.find(
+    (item) => item.providerID === selected.model.providerID && item.id === selected.model.modelID,
+  )
+  if (!model) throw new ACPError.InvalidModelError({ providerId: selected.model.providerID, modelId: modelID })
+  if (selected.variant && !model.variants.some((variant) => variant.id === selected.variant))
+    throw new ACPError.InvalidEffortError({ effort: selected.variant })
+  return { providerID: model.providerID, id: model.id, variant: selected.variant }
+}
+
+async function selectMode(client: OpenCodeClient, state: Attached, modeID: string) {
+  if (!state.catalog.modes.some((mode) => mode.id === modeID)) throw new ACPError.InvalidModeError({ mode: modeID })
+  state.modeID = modeID
+  await client.session.switchAgent({ sessionID: state.id, agent: modeID })
+}
+
+async function getSession(client: OpenCodeClient, sessionID: string) {
+  return client.session.get({ sessionID }).catch((error) => {
+    if (isSessionNotFoundError(error)) throw new ACPError.SessionNotFoundError({ sessionId: sessionID })
+    throw error
+  })
+}
+
+async function messages(client: OpenCodeClient, sessionID: string) {
+  const result: SessionMessageInfo[] = []
+  let cursor: string | undefined
+  do {
+    const page = cursor
+      ? await client.message.list({ sessionID, limit: 200, cursor })
+      : await client.message.list({ sessionID, limit: 200, order: "asc" })
+    result.push(...page.data)
+    cursor = page.cursor.next ?? undefined
+  } while (cursor)
+  return result
+}
+
+async function registerMcpServers(
+  client: OpenCodeClient,
+  registered: Map<string, Set<string>>,
+  session: Attached,
+  servers: readonly McpServer[],
+) {
+  const current = registered.get(session.id) ?? new Set<string>()
+  registered.set(session.id, current)
+  await Promise.all(
+    servers.flatMap((server) => {
+      const config = mcpConfig(server)
+      const key = `${server.name}:${stableStringify(config)}`
+      if (current.has(key)) return []
+      current.add(key)
+      return [
+        client.mcp.add({ server: server.name, location: { directory: session.cwd }, config }).catch((error) => {
+          current.delete(key)
+          throw error
+        }),
+      ]
+    }),
+  )
+}
+
+function mcpConfig(server: McpServer) {
+  if ("type" in server) {
+    return {
+      type: "remote" as const,
+      url: server.url,
+      headers: Object.fromEntries(server.headers.map((header) => [header.name, header.value])),
+      oauth: false as const,
+    }
+  }
+  return {
+    type: "local" as const,
+    command: [server.command, ...server.args],
+    environment: Object.fromEntries(server.env.map((entry) => [entry.name, entry.value])),
+  }
+}
+
+function stableStringify(value: unknown): string {
+  if (Array.isArray(value)) return `[${value.map(stableStringify).join(",")}]`
+  if (!value || typeof value !== "object") return JSON.stringify(value)
+  return `{${Object.entries(value)
+    .toSorted(([a], [b]) => a.localeCompare(b))
+    .map(([key, item]) => `${JSON.stringify(key)}:${stableStringify(item)}`)
+    .join(",")}}`
+}
+
+async function sendUsageUpdate(client: OpenCodeClient, connection: Connection, session: Attached, used?: number) {
+  if (!used) return
+  const model = session.catalog.models.find(
+    (item) => item.providerID === session.model.providerID && item.id === session.model.id,
+  )
+  if (!model?.limit.context) return
+  const info = await client.session.get({ sessionID: session.id })
+  await connection.sessionUpdate({
+    sessionId: session.id,
+    update: {
+      sessionUpdate: "usage_update",
+      used,
+      size: model.limit.context,
+      cost: { amount: info.cost, currency: "USD" },
+    },
+  })
+}
+
+function detectSlashCommand(text: string): { readonly name: string; readonly args: string } | undefined {
+  const value = text.trim()
+  if (!value.startsWith("/")) return undefined
+  const [name, ...rest] = value.slice(1).split(/\s+/)
+  if (!name) return undefined
+  return { name, args: rest.join(" ").trim() }
+}
+
+export * as ACPService from "./service"

packages/cli/src/acp/tool.ts

@@ -0,0 +1,222 @@
+import { isAbsolute, resolve } from "node:path"
+import type { ToolCall, ToolCallContent, ToolCallLocation, ToolCallUpdate, ToolKind } from "@agentclientprotocol/sdk"
+
+export type ToolInput = Record<string, unknown>
+export type ToolContent = ReadonlyArray<
+  | { readonly type: "text"; readonly text: string }
+  | { readonly type: "file"; readonly uri: string; readonly mime: string; readonly name?: string }
+>
+
+export function toToolKind(toolName: string): ToolKind {
+  switch (toolName.toLocaleLowerCase()) {
+    case "bash":
+    case "shell":
+      return "execute"
+    case "webfetch":
+      return "fetch"
+    case "edit":
+    case "apply_patch":
+    case "patch":
+    case "write":
+      return "edit"
+    case "grep":
+    case "glob":
+    case "context":
+    case "context7_resolve_library_id":
+    case "context7_get_library_docs":
+      return "search"
+    case "read":
+      return "read"
+    case "task":
+    case "subagent":
+      return "think"
+    default:
+      return "other"
+  }
+}
+
+export function toLocations(toolName: string, input: ToolInput, cwd?: string): ToolCallLocation[] {
+  switch (toolName.toLocaleLowerCase()) {
+    case "bash":
+    case "shell": {
+      const workdir = shellWorkdir(input, cwd)
+      return workdir ? [{ path: workdir }] : []
+    }
+    case "read":
+    case "edit":
+    case "write":
+    case "patch":
+    case "apply_patch":
+      return locationFrom(input.filePath ?? input.filepath)
+    case "external_directory":
+      return locationFrom(input.filePath ?? input.filepath, input.parentDir, input.directories)
+    case "grep":
+    case "glob":
+    case "context":
+    case "context7_resolve_library_id":
+    case "context7_get_library_docs":
+      return locationFrom(input.path)
+    default:
+      return []
+  }
+}
+
+export function pendingToolCall(input: {
+  readonly toolCallId: string
+  readonly toolName: string
+  readonly state: { readonly input: ToolInput; readonly title?: string }
+  readonly cwd?: string
+}): ToolCall {
+  return {
+    toolCallId: input.toolCallId,
+    title: toolTitle(input.toolName, input.state.input, input.state.title),
+    kind: toToolKind(input.toolName),
+    status: "pending",
+    locations: toLocations(input.toolName, input.state.input, input.cwd),
+    rawInput: rawInput(input.toolName, input.state.input, input.cwd),
+  }
+}
+
+export function runningToolUpdate(input: {
+  readonly toolCallId: string
+  readonly toolName: string
+  readonly state: { readonly input: ToolInput; readonly title?: string }
+  readonly content?: ToolContent
+  readonly cwd?: string
+}): ToolCallUpdate {
+  return {
+    toolCallId: input.toolCallId,
+    status: "in_progress",
+    kind: toToolKind(input.toolName),
+    title: toolTitle(input.toolName, input.state.input, input.state.title),
+    locations: toLocations(input.toolName, input.state.input, input.cwd),
+    rawInput: rawInput(input.toolName, input.state.input, input.cwd),
+    ...(input.content?.length ? { content: toolContent(input.content) } : {}),
+  }
+}
+
+export function completedToolUpdate(input: {
+  readonly toolCallId: string
+  readonly toolName: string
+  readonly input: ToolInput
+  readonly content: ToolContent
+  readonly structured: Readonly<Record<string, unknown>>
+  readonly result?: unknown
+}): ToolCallUpdate {
+  const normalized = toolContent(input.content)
+  const read = input.toolName.toLocaleLowerCase() === "read" ? readDisplayText(input.structured) : undefined
+  const images = normalized.filter((part) => part.type === "content" && part.content.type === "image")
+  const primary =
+    read === undefined
+      ? normalized.filter((part) => !images.includes(part))
+      : [{ type: "content" as const, content: { type: "text" as const, text: read } }]
+  const oldText = stringValue(input.input.oldString)
+  const newText = stringValue(input.input.newString)
+  const diff: ToolCallContent[] =
+    oldText === undefined || newText === undefined
+      ? []
+      : [
+          {
+            type: "diff",
+            path: stringValue(input.input.path) ?? stringValue(input.input.filePath) ?? "",
+            oldText,
+            newText,
+          },
+        ]
+  return {
+    toolCallId: input.toolCallId,
+    status: "completed",
+    content: [...primary, ...diff, ...images],
+    rawOutput: {
+      structured: input.structured,
+      ...(input.result === undefined ? {} : { result: input.result }),
+    },
+  }
+}
+
+export function errorToolUpdate(input: {
+  readonly toolCallId: string
+  readonly toolName: string
+  readonly input: ToolInput
+  readonly content: ToolContent
+  readonly structured: Readonly<Record<string, unknown>>
+  readonly error: string
+  readonly cwd?: string
+}): ToolCallUpdate {
+  return {
+    toolCallId: input.toolCallId,
+    status: "failed",
+    kind: toToolKind(input.toolName),
+    title: toolTitle(input.toolName, input.input, undefined),
+    locations: toLocations(input.toolName, input.input, input.cwd),
+    rawInput: rawInput(input.toolName, input.input, input.cwd),
+    content: [...toolContent(input.content), { type: "content", content: { type: "text", text: input.error } }],
+    rawOutput: { structured: input.structured, error: input.error },
+  }
+}
+
+function toolContent(content: ToolContent): ToolCallContent[] {
+  return content.flatMap((part): ToolCallContent[] => {
+    if (part.type === "text") return [{ type: "content", content: { type: "text", text: part.text } }]
+    const match = /^data:([^;,]+)(?:;[^,]*)*;base64,(.*)$/.exec(part.uri)
+    if (!match?.[1]?.startsWith("image/") || match[2] === undefined) return []
+    return [{ type: "content", content: { type: "image", mimeType: match[1], data: match[2] } }]
+  })
+}
+
+function readDisplayText(structured: Readonly<Record<string, unknown>>) {
+  if (typeof structured.content === "string") {
+    if (structured.type === "text-page" || structured.encoding === "utf8") return structured.content
+  }
+  if (!Array.isArray(structured.entries)) return undefined
+  return structured.entries
+    .flatMap((entry): string[] => {
+      if (typeof entry === "string") return [entry]
+      if (!entry || typeof entry !== "object") return []
+      const path = Reflect.get(entry, "path")
+      return typeof path === "string" ? [path] : []
+    })
+    .join("\n")
+}
+
+function toolTitle(toolName: string, input: ToolInput, fallback: string | undefined) {
+  if (isShell(toolName)) return stringValue(input.command) ?? stringValue(input.cmd) ?? fallback ?? toolName
+  return fallback || toolName
+}
+
+function rawInput(toolName: string, input: ToolInput, cwd?: string): ToolInput {
+  if (!isShell(toolName) || input.cwd || input.workdir) return input
+  const workdir = shellWorkdir(input, cwd)
+  return workdir ? { ...input, cwd: workdir } : input
+}
+
+function shellWorkdir(input: ToolInput, cwd?: string) {
+  const explicit = stringValue(input.workdir) ?? stringValue(input.cwd)
+  if (!explicit) return cwd
+  return isAbsolute(explicit) ? explicit : resolve(cwd ?? process.cwd(), explicit)
+}
+
+function isShell(toolName: string) {
+  const tool = toolName.toLocaleLowerCase()
+  return tool === "bash" || tool === "shell"
+}
+
+function locationFrom(...values: unknown[]): ToolCallLocation[] {
+  return Array.from(
+    new Set(
+      values.flatMap((value): string[] => {
+        if (Array.isArray(value))
+          return value.filter((item): item is string => typeof item === "string" && item.length > 0)
+        const path = stringValue(value)
+        return path ? [path] : []
+      }),
+    ),
+    (path) => ({ path }),
+  )
+}
+
+export function stringValue(value: unknown) {
+  return typeof value === "string" ? value : undefined
+}
+
+export * as ACPTool from "./tool"

packages/cli/src/commands/commands.ts

@@ -34,6 +34,7 @@ export const Commands = Spec.make(typeof OPENCODE_CLI_NAME === "string" ? OPENCO
     ),
   },
   commands: [
+    Spec.make("acp", { description: "Start an Agent Client Protocol server" }),
     Spec.make("api", {
       description: "Make a request to the running server",
       params: {

packages/cli/src/commands/handlers/acp.ts

@@ -0,0 +1,36 @@
+import { AgentSideConnection, ndJsonStream } from "@agentclientprotocol/sdk"
+import { OpenCode } from "@opencode-ai/client/promise"
+import { Service } from "@opencode-ai/client/effect/service"
+import { Effect } from "effect"
+import { ACP } from "../../acp/agent"
+import { Commands } from "../commands"
+import { Runtime } from "../../framework/runtime"
+import { Standalone } from "../../services/standalone"
+
+export default Runtime.handler(
+  Commands.commands.acp,
+  Effect.fn("cli.acp")(function* () {
+    process.env.OPENCODE_CLIENT = "acp"
+    const endpoint = yield* Standalone.start()
+    const client = OpenCode.make({ baseUrl: endpoint.url, headers: Service.headers(endpoint) })
+    const input = new WritableStream<Uint8Array>({
+      write: (chunk) =>
+        new Promise<void>((resolve, reject) => {
+          process.stdout.write(chunk, (error) => (error ? reject(error) : resolve()))
+        }),
+    })
+    const output = new ReadableStream<Uint8Array>({
+      start(controller) {
+        process.stdin.on("data", (chunk: Buffer) => controller.enqueue(new Uint8Array(chunk)))
+        process.stdin.on("end", () => controller.close())
+        process.stdin.on("error", (error) => controller.error(error))
+      },
+    })
+    const stream = ndJsonStream(input, output)
+    const connection = new AgentSideConnection((connection) => ACP.create(client, connection), stream)
+    process.stdin.resume()
+    yield* Effect.promise(() => connection.closed)
+    // EOF owns this stdio process; exiting also closes the private server's lease pipe.
+    yield* Effect.sync(() => process.exit(0))
+  }),
+)

packages/cli/src/index.ts

@@ -15,6 +15,7 @@ import { Npm } from "@opencode-ai/util/npm"
 
 const Handlers = Runtime.handlers(Commands, {
   $: () => import("./commands/handlers/default"),
+  acp: () => import("./commands/handlers/acp"),
   api: () => import("./commands/handlers/api"),
   auth: {
     connect: () => import("./commands/handlers/auth/connect"),

packages/cli/test/acp/command.test.ts

@@ -0,0 +1,107 @@
+import { afterEach, describe, expect, test } from "bun:test"
+import path from "node:path"
+
+type Message = { readonly id?: number; readonly result?: unknown; readonly error?: unknown }
+const children: Bun.Subprocess[] = []
+
+afterEach(async () => {
+  await Promise.all(
+    children.splice(0).map(async (child) => {
+      child.kill("SIGKILL")
+      await child.exited
+    }),
+  )
+})
+
+describe("acp command", () => {
+  test("is registered", async () => {
+    const result = await cli(["--help"])
+    expect(result.exitCode).toBe(0)
+    expect(result.stdout).toContain("acp        Start an Agent Client Protocol server")
+  })
+
+  test("initializes over ndjson and exits on stdin eof", async () => {
+    const child = spawn()
+    const stderr = new Response(child.stderr).text()
+    await child.stdin.write(
+      new TextEncoder().encode(
+        JSON.stringify({
+          jsonrpc: "2.0",
+          id: 1,
+          method: "initialize",
+          params: {
+            protocolVersion: 1,
+            clientCapabilities: {},
+            clientInfo: { name: "test", version: "1.0.0" },
+          },
+        }) + "\n",
+      ),
+    )
+    await child.stdin.flush()
+    const response = await readMessage(child.stdout)
+    expect(response.id).toBe(1)
+    expect(response.error).toBeUndefined()
+    expect(response.result).toMatchObject({
+      protocolVersion: 1,
+      agentCapabilities: { loadSession: true },
+      agentInfo: { name: "OpenCode" },
+    })
+
+    await child.stdin.end()
+    const exitCode = await child.exited
+    const errorOutput = await stderr
+    if (exitCode !== 0) throw new Error(`ACP exited with ${exitCode}: ${errorOutput}`)
+    children.splice(children.indexOf(child), 1)
+  }, 30_000)
+})
+
+function spawn() {
+  const child = Bun.spawn([process.execPath, "run", "src/index.ts", "acp"], {
+    cwd: path.join(import.meta.dir, "../.."),
+    stdin: "pipe",
+    stdout: "pipe",
+    stderr: "pipe",
+  })
+  children.push(child)
+  return child
+}
+
+async function readMessage(stream: ReadableStream<Uint8Array>) {
+  const reader = stream.getReader()
+  const decoder = new TextDecoder()
+  let output = ""
+  while (true) {
+    const result = await Promise.race([
+      reader.read(),
+      Bun.sleep(20_000).then(() => {
+        throw new Error("timed out waiting for ACP response")
+      }),
+    ])
+    if (result.done) throw new Error(`ACP exited before responding: ${output}`)
+    output += decoder.decode(result.value, { stream: true })
+    const newline = output.indexOf("\n")
+    if (newline === -1) continue
+    reader.releaseLock()
+    const message: unknown = JSON.parse(output.slice(0, newline))
+    if (!isMessage(message)) throw new Error(`invalid ACP response: ${output.slice(0, newline)}`)
+    return message
+  }
+}
+
+function isMessage(value: unknown): value is Message {
+  return typeof value === "object" && value !== null
+}
+
+async function cli(args: string[]) {
+  const child = Bun.spawn([process.execPath, "run", "src/index.ts", ...args], {
+    cwd: path.join(import.meta.dir, "../.."),
+    stdout: "pipe",
+    stderr: "pipe",
+  })
+  const [stdout, stderr, exitCode] = await Promise.all([
+    new Response(child.stdout).text(),
+    new Response(child.stderr).text(),
+    child.exited,
+  ])
+  return { stdout, stderr, exitCode }
+}

packages/cli/test/acp/config-option.test.ts

@@ -0,0 +1,151 @@
+import { describe, expect, test } from "bun:test"
+import {
+  buildConfigOptions,
+  buildEffortSelectOption,
+  buildModeSelectOption,
+  buildModelSelectOption,
+  formatVariantName,
+  parseModelSelection,
+  type ConfigOptionProvider,
+} from "../../src/acp/config-option"
+
+const providers: ConfigOptionProvider[] = [
+  {
+    id: "anthropic",
+    name: "Anthropic",
+    models: [
+      { id: "claude/sonnet-4", name: "Claude Sonnet 4", variants: ["default", "high", "very-high"] },
+      { id: "claude-haiku", name: "Claude Haiku" },
+    ],
+  },
+  { id: "openai", name: "OpenAI", models: [{ id: "gpt-5", name: "GPT-5", variants: ["minimal", "low"] }] },
+]
+
+describe("acp config options", () => {
+  test("builds the model select option with ACP verifier category", () => {
+    expect(
+      buildModelSelectOption({
+        providers,
+        currentModel: { providerID: "anthropic", modelID: "claude/sonnet-4" },
+      }),
+    ).toEqual({
+      id: "model",
+      name: "Model",
+      category: "model",
+      type: "select",
+      currentValue: "anthropic/claude/sonnet-4",
+      options: [
+        { value: "anthropic/claude-haiku", name: "Anthropic/Claude Haiku" },
+        { value: "anthropic/claude/sonnet-4", name: "Anthropic/Claude Sonnet 4" },
+        { value: "openai/gpt-5", name: "OpenAI/GPT-5" },
+      ],
+    })
+  })
+
+  test("builds effort option from variants and falls back to default when current variant is invalid", () => {
+    expect(buildEffortSelectOption({ variants: ["low", "default", "high"], currentVariant: "missing" })).toEqual({
+      id: "effort",
+      name: "Effort",
+      description: "Available effort levels for this model",
+      category: "thought_level",
+      type: "select",
+      currentValue: "default",
+      options: [
+        { value: "low", name: "Low" },
+        { value: "default", name: "Default" },
+        { value: "high", name: "High" },
+      ],
+    })
+  })
+
+  test("effort fallback uses the first variant when default is absent", () => {
+    expect(buildEffortSelectOption({ variants: ["minimal", "low"], currentVariant: "missing" }).currentValue).toBe(
+      "minimal",
+    )
+  })
+
+  test("builds the mode select option with descriptions when present", () => {
+    expect(
+      buildModeSelectOption({
+        currentModeId: "build",
+        modes: [
+          { id: "build", name: "Build", description: "Make code changes" },
+          { id: "plan", name: "Plan" },
+        ],
+      }),
+    ).toEqual({
+      id: "mode",
+      name: "Session Mode",
+      category: "mode",
+      type: "select",
+      currentValue: "build",
+      options: [
+        { value: "build", name: "Build", description: "Make code changes" },
+        { value: "plan", name: "Plan" },
+      ],
+    })
+  })
+
+  test("builds full config options with model, effort, and mode in stable order", () => {
+    const options = buildConfigOptions({
+      providers,
+      currentModel: { providerID: "anthropic", modelID: "claude/sonnet-4" },
+      currentVariant: "very-high",
+      modes: [
+        { id: "build", name: "Build" },
+        { id: "plan", name: "Plan" },
+      ],
+      currentModeId: "plan",
+    })
+
+    expect(options.map((option) => option.id)).toEqual(["model", "effort", "mode"])
+    expect(options.map((option) => option.category)).toEqual(["model", "thought_level", "mode"])
+    expect(options[0]?.currentValue).toBe("anthropic/claude/sonnet-4")
+    expect(options[1]?.currentValue).toBe("very-high")
+  })
+
+  test("full config options omit effort for models without variants", () => {
+    expect(
+      buildConfigOptions({
+        providers,
+        currentModel: { providerID: "anthropic", modelID: "claude-haiku" },
+      }).map((option) => option.id),
+    ).toEqual(["model"])
+  })
+
+  test("parses provider/model selections", () => {
+    expect(parseModelSelection("openai/gpt-5", providers)).toEqual({
+      model: { providerID: "openai", modelID: "gpt-5" },
+    })
+  })
+
+  test("parses provider/model/variant selections when the base model exposes that variant", () => {
+    expect(parseModelSelection("openai/gpt-5/low", providers)).toEqual({
+      model: { providerID: "openai", modelID: "gpt-5" },
+      variant: "low",
+    })
+  })
+
+  test("prefers exact slash-containing model ids before treating the tail as a variant", () => {
+    expect(parseModelSelection("anthropic/claude/sonnet-4", providers)).toEqual({
+      model: { providerID: "anthropic", modelID: "claude/sonnet-4" },
+    })
+  })
+
+  test("parses trailing variants for slash-containing model ids", () => {
+    expect(parseModelSelection("anthropic/claude/sonnet-4/high", providers)).toEqual({
+      model: { providerID: "anthropic", modelID: "claude/sonnet-4" },
+      variant: "high",
+    })
+  })
+
+  test("keeps unknown trailing segments in the model id when they are not valid variants", () => {
+    expect(parseModelSelection("anthropic/claude/sonnet-4/missing", providers)).toEqual({
+      model: { providerID: "anthropic", modelID: "claude/sonnet-4/missing" },
+    })
+  })
+
+  test("formats variant names for display", () => {
+    expect(formatVariantName("very_high-effort")).toBe("Very High Effort")
+  })
+})

packages/cli/test/acp/config-options.subprocess.test.ts

@@ -0,0 +1,74 @@
+import type { SetSessionConfigOptionResponse } from "@agentclientprotocol/sdk"
+import { describe, expect, test } from "bun:test"
+import {
+  alternateValue,
+  createAcpFixture,
+  expectOk,
+  flattenSelectOptions,
+  initialize,
+  newSession,
+  requireSelectOption,
+  selectConfigOption,
+} from "./subprocess"
+
+describe("acp config option subprocess", () => {
+  test('model option is listed with category "model"', async () => {
+    await using fixture = await createAcpFixture()
+    const acp = fixture.spawn()
+    await initialize(acp)
+    const model = requireSelectOption((await newSession(acp, fixture.home)).configOptions, "model")
+
+    expect(model.category).toBe("model")
+    expect(model.currentValue).toBe("test/test-model")
+    expect(flattenSelectOptions(model).length).toBeGreaterThanOrEqual(2)
+  }, 60_000)
+
+  test("model switch updates currentValue", async () => {
+    await using fixture = await createAcpFixture()
+    const acp = fixture.spawn()
+    await initialize(acp)
+    const session = await newSession(acp, fixture.home)
+    const model = requireSelectOption(session.configOptions, "model")
+    const nextModel = flattenSelectOptions(model).find((option) => option.value === "test/second-model")?.value
+    expect(nextModel).toBe("test/second-model")
+
+    const updated = expectOk(
+      await acp.request<SetSessionConfigOptionResponse>("session/set_config_option", {
+        sessionId: session.sessionId,
+        configId: "model",
+        value: nextModel,
+      }),
+    )
+
+    expect(selectConfigOption(updated.configOptions, "model")?.currentValue).toBe(nextModel)
+  }, 60_000)
+
+  test('effort option is listed with category "thought_level" when selected model supports variants', async () => {
+    await using fixture = await createAcpFixture()
+    const acp = fixture.spawn()
+    await initialize(acp)
+    const effort = requireSelectOption((await newSession(acp, fixture.home)).configOptions, "effort")
+
+    expect(effort.category).toBe("thought_level")
+    expect(effort.currentValue).toBe("low")
+    expect(flattenSelectOptions(effort).map((option) => option.value)).toEqual(["low", "high"])
+  }, 60_000)
+
+  test("effort switch updates currentValue", async () => {
+    await using fixture = await createAcpFixture()
+    const acp = fixture.spawn()
+    await initialize(acp)
+    const session = await newSession(acp, fixture.home)
+    const nextEffort = alternateValue(requireSelectOption(session.configOptions, "effort"))
+
+    const updated = expectOk(
+      await acp.request<SetSessionConfigOptionResponse>("session/set_config_option", {
+        sessionId: session.sessionId,
+        configId: "effort",
+        value: nextEffort,
+      }),
+    )
+
+    expect(selectConfigOption(updated.configOptions, "effort")?.currentValue).toBe(nextEffort)
+  }, 60_000)
+})

packages/cli/test/acp/content.test.ts

@@ -0,0 +1,239 @@
+import { describe, expect, test } from "bun:test"
+import { pathToFileURL } from "node:url"
+import { contentBlockToParts, partsToContentChunks, promptContentToParts } from "../../src/acp/content"
+
+describe("acp content conversion", () => {
+  test("plain text block becomes a text part", () => {
+    expect(contentBlockToParts({ type: "text", text: "hello" })).toEqual([{ type: "text", text: "hello" }])
+  })
+
+  test("assistant-only text audience becomes synthetic", () => {
+    expect(
+      contentBlockToParts({
+        type: "text",
+        text: "internal",
+        annotations: { audience: ["assistant"] },
+      }),
+    ).toEqual([{ type: "text", text: "internal", synthetic: true }])
+  })
+
+  test("user-only text audience becomes ignored", () => {
+    expect(
+      contentBlockToParts({
+        type: "text",
+        text: "visible to user",
+        annotations: { audience: ["user"] },
+      }),
+    ).toEqual([{ type: "text", text: "visible to user", ignored: true }])
+  })
+
+  test("image block with base64 data becomes a data URL file part", () => {
+    expect(
+      contentBlockToParts({
+        type: "image",
+        data: "AAAA",
+        mimeType: "image/png",
+        uri: "file:///tmp/screenshot.png",
+      }),
+    ).toEqual([
+      {
+        type: "file",
+        url: "data:image/png;base64,AAAA",
+        filename: "screenshot.png",
+        mime: "image/png",
+      },
+    ])
+  })
+
+  test("image block with http URI becomes a file part", () => {
+    expect(
+      contentBlockToParts({
+        type: "image",
+        data: "",
+        mimeType: "image/jpeg",
+        uri: "http://example.com/assets/photo.jpg",
+      }),
+    ).toEqual([
+      {
+        type: "file",
+        url: "http://example.com/assets/photo.jpg",
+        filename: "photo.jpg",
+        mime: "image/jpeg",
+      },
+    ])
+  })
+
+  test("resource_link file URL becomes a file part with name and fallback mime", () => {
+    expect(
+      contentBlockToParts({
+        type: "resource_link",
+        uri: "file:///tmp/notes.txt",
+        name: "client-notes.txt",
+      }),
+    ).toEqual([
+      {
+        type: "file",
+        url: "file:///tmp/notes.txt",
+        filename: "client-notes.txt",
+        mime: "text/plain",
+      },
+    ])
+  })
+
+  test("resource_link zed path becomes a file URL part", () => {
+    expect(
+      contentBlockToParts({
+        type: "resource_link",
+        uri: "zed://workspace?path=/tmp/project/src/app.ts",
+        name: "app.ts",
+        mimeType: "text/typescript",
+      }),
+    ).toEqual([
+      {
+        type: "file",
+        url: pathToFileURL("/tmp/project/src/app.ts").href,
+        filename: "app.ts",
+        mime: "text/typescript",
+      },
+    ])
+  })
+
+  test("resource with text becomes a sourced text part", () => {
+    const result = contentBlockToParts({
+      type: "resource",
+      resource: {
+        uri: "file:///tmp/context.txt#L12-L14",
+        mimeType: "text/plain",
+        text: "context",
+      },
+    })
+    expect(result).toHaveLength(1)
+    expect(result[0]?.type).toBe("text")
+    if (result[0]?.type === "text") {
+      expect(result[0].text.endsWith("\ncontext")).toBe(true)
+      expect(result[0].text.includes("context.txt")).toBe(true)
+      expect(result[0].text.includes("12")).toBe(true)
+    }
+  })
+
+  test("resource with text uses URI fallback for non-file resources", () => {
+    expect(
+      contentBlockToParts({
+        type: "resource",
+        resource: {
+          uri: "mcp://server/context",
+          text: "context",
+        },
+      }),
+    ).toEqual([{ type: "text", text: "[mcp://server/context]\ncontext" }])
+  })
+
+  test("resource with text includes file path", () => {
+    const result = contentBlockToParts({
+      type: "resource",
+      resource: {
+        uri: "file:///tmp/context.txt",
+        mimeType: "text/plain",
+        text: "context",
+      },
+    })
+    expect(result).toHaveLength(1)
+    expect(result[0]?.type).toBe("text")
+    if (result[0]?.type === "text") {
+      expect(result[0].text.endsWith("\ncontext")).toBe(true)
+      expect(result[0].text.includes("context.txt")).toBe(true)
+    }
+  })
+
+  test("resource with blob and mimeType becomes a data URL file part", () => {
+    expect(
+      contentBlockToParts({
+        type: "resource",
+        resource: {
+          uri: "file:///tmp/report.pdf",
+          mimeType: "application/pdf",
+          blob: "JVBERg==",
+        },
+      }),
+    ).toEqual([
+      {
+        type: "file",
+        url: "data:application/pdf;base64,JVBERg==",
+        filename: "report.pdf",
+        mime: "application/pdf",
+      },
+    ])
+  })
+
+  test("data URL resource is preserved as a file part", () => {
+    expect(
+      contentBlockToParts({
+        type: "resource",
+        resource: {
+          uri: "data:text/plain;base64,aGVsbG8=",
+          mimeType: "text/plain",
+          blob: "ignored",
+        },
+      }),
+    ).toEqual([
+      {
+        type: "file",
+        url: "data:text/plain;base64,aGVsbG8=",
+        filename: "file",
+        mime: "text/plain",
+      },
+    ])
+  })
+
+  test("unsupported blocks are ignored", () => {
+    expect(promptContentToParts([{ type: "audio", data: "AAAA", mimeType: "audio/wav" }])).toEqual([])
+    expect(
+      promptContentToParts([
+        // @ts-expect-error Exercise forward compatibility with an unknown ACP content block.
+        { type: "unknown", text: "skip" },
+      ]),
+    ).toEqual([])
+  })
+})
+
+describe("acp replay conversion", () => {
+  test("replays text audience annotations", () => {
+    expect(partsToContentChunks([{ type: "text", text: "cached", synthetic: true }])).toEqual([
+      {
+        content: {
+          type: "text",
+          text: "cached",
+          annotations: { audience: ["assistant"] },
+        },
+      },
+    ])
+  })
+
+  test("replays file and data URL parts as ACP content", () => {
+    expect(
+      partsToContentChunks([
+        { type: "file", url: "file:///tmp/readme.md", filename: "readme.md", mime: "text/markdown" },
+        { type: "file", url: "data:text/plain;base64,aGVsbG8=", filename: "note.txt", mime: "text/plain" },
+      ]),
+    ).toEqual([
+      {
+        content: {
+          type: "resource_link",
+          uri: "file:///tmp/readme.md",
+          name: "readme.md",
+          mimeType: "text/markdown",
+        },
+      },
+      {
+        content: {
+          type: "resource",
+          resource: {
+            uri: pathToFileURL("note.txt").href,
+            mimeType: "text/plain",
+            text: "hello",
+          },
+        },
+      },
+    ])
+  })
+})

packages/cli/test/acp/error.test.ts

@@ -0,0 +1,60 @@
+import { describe, expect, test } from "bun:test"
+import { RequestError } from "@agentclientprotocol/sdk"
+import { ACPError } from "../../src/acp/error"
+
+describe("acp errors", () => {
+  test("maps validation failures to invalid params", () => {
+    const cases: ACPError.Error[] = [
+      new ACPError.SessionNotFoundError({ sessionId: "ses_missing" }),
+      new ACPError.InvalidConfigOptionError({ configId: "temperature" }),
+      new ACPError.InvalidModelError({ providerId: "anthropic", modelId: "claude-missing" }),
+      new ACPError.InvalidEffortError({ effort: "extreme" }),
+      new ACPError.InvalidModeError({ mode: "turbo" }),
+    ]
+
+    expect(cases.map((error) => ACPError.toRequestError(error).code)).toEqual([-32602, -32602, -32602, -32602, -32602])
+  })
+
+  test("includes safe validation details", () => {
+    expect(ACPError.toRequestError(new ACPError.SessionNotFoundError({ sessionId: "ses_123" }))).toMatchObject({
+      code: -32602,
+      data: { sessionId: "ses_123" },
+    })
+    expect(ACPError.toRequestError(new ACPError.InvalidModelError({ modelId: "gpt-missing" }))).toMatchObject({
+      code: -32602,
+      data: { modelId: "gpt-missing" },
+    })
+  })
+
+  test("maps auth required to the SDK auth error", () => {
+    const requestError = ACPError.toRequestError(new ACPError.AuthRequiredError())
+
+    expect(requestError).toBeInstanceOf(RequestError)
+    expect(requestError.code).toBe(-32000)
+    expect(requestError.message).toBe("Authentication required: provider authentication required")
+    expect(requestError.data).toEqual({})
+  })
+
+  test("maps service failures to safe internal errors", () => {
+    const requestError = ACPError.toRequestError(
+      new ACPError.ServiceFailureError({ service: "provider", safeMessage: "Provider request failed" }),
+    )
+
+    expect(requestError.code).toBe(-32603)
+    expect(requestError.message).toBe("Internal error: Provider request failed")
+    expect(requestError.data).toEqual({ service: "provider" })
+  })
+
+  test("wraps unknown defects without leaking raw details", () => {
+    const requestError = ACPError.toRequestError(
+      ACPError.fromUnknown(new Error("stack has sk-ant-secret and oauth refresh token")),
+    )
+    const serialized = JSON.stringify(requestError.toErrorResponse())
+
+    expect(requestError.code).toBe(-32603)
+    expect(requestError.message).toBe("Internal error: Internal service failure")
+    expect(serialized).not.toContain("sk-ant-secret")
+    expect(serialized).not.toContain("oauth refresh token")
+    expect(serialized).not.toContain("stack")
+  })
+})

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

@@ -0,0 +1,684 @@
+import { describe, expect, test } from "bun:test"
+import type { AgentSideConnection } from "@agentclientprotocol/sdk"
+import type { SessionMessageInfo } from "@opencode-ai/client/promise"
+import { resolve } from "node:path"
+import { replayMessages, streamTurn, type TurnControl } from "../../src/acp/event"
+import { createSseFixture, durableEvent, ephemeralEvent, withTimeout } from "./sse-fixture"
+
+type SessionUpdateParams = Parameters<AgentSideConnection["sessionUpdate"]>[0]
+type Connection = Pick<AgentSideConnection, "sessionUpdate" | "requestPermission">
+type Fixture = ReturnType<typeof createSseFixture>
+
+describe("acp event behavior", () => {
+  test("subscribes before admission and isolates sessions and input IDs", async () => {
+    const updates: SessionUpdateParams[] = []
+    const fixture = createSseFixture({
+      onPrompt({ id, send }) {
+        send(
+          ephemeralEvent("session.text.delta", {
+            sessionID: "ses_a",
+            assistantMessageID: "msg_before",
+            ordinal: 0,
+            delta: "before admission",
+          }),
+        )
+        send(durableEvent("session.input.promoted", { sessionID: "ses_b", inputID: id }))
+        send(durableEvent("session.input.promoted", { sessionID: "ses_a", inputID: "input_other" }))
+        send(
+          ephemeralEvent("session.text.delta", {
+            sessionID: "ses_a",
+            assistantMessageID: "msg_wrong_input",
+            ordinal: 0,
+            delta: "wrong input",
+          }),
+        )
+        send(durableEvent("session.input.promoted", { sessionID: "ses_a", inputID: id }))
+        send(
+          ephemeralEvent("session.text.delta", {
+            sessionID: "ses_b",
+            assistantMessageID: "msg_b",
+            ordinal: 0,
+            delta: "other session",
+          }),
+        )
+        send(
+          ephemeralEvent("session.text.delta", {
+            sessionID: "ses_a",
+            assistantMessageID: "msg_a",
+            ordinal: 0,
+            delta: "accepted",
+          }),
+        )
+        send(
+          durableEvent("session.step.ended", {
+            sessionID: "ses_a",
+            assistantMessageID: "msg_a",
+            finish: "stop",
+            cost: 0,
+            tokens: tokens(),
+          }),
+        )
+        send(durableEvent("session.execution.succeeded", { sessionID: "ses_b" }))
+        send(durableEvent("session.execution.succeeded", { sessionID: "ses_a" }))
+      },
+    })
+
+    try {
+      const response = await turn({
+        fixture,
+        connection: recordingConnection(updates),
+        sessionID: "ses_a",
+        inputID: "input_a",
+      })
+
+      expect(fixture.requests.slice(0, 2).map((request) => request.path)).toEqual([
+        "/api/event",
+        "/api/session/ses_a/prompt",
+      ])
+      expect(updates).toEqual([
+        {
+          sessionId: "ses_a",
+          update: {
+            sessionUpdate: "agent_message_chunk",
+            messageId: "msg_a",
+            content: { type: "text", text: "accepted" },
+          },
+        },
+      ])
+      expect(response.stopReason).toBe("end_turn")
+    } finally {
+      await fixture.stop()
+    }
+  })
+
+  test("preserves text and reasoning order before returning the terminal response", async () => {
+    const firstUpdate = Promise.withResolvers<void>()
+    const releaseUpdate = Promise.withResolvers<void>()
+    const allUpdates = Promise.withResolvers<void>()
+    const releaseSubmit = Promise.withResolvers<void>()
+    const updates: SessionUpdateParams[] = []
+    const fixture = createSseFixture({
+      async onPrompt({ id, send }) {
+        send(durableEvent("session.input.promoted", { sessionID: "ses_order", inputID: id }))
+        send(
+          ephemeralEvent("session.reasoning.delta", {
+            sessionID: "ses_order",
+            assistantMessageID: "msg_order",
+            ordinal: 0,
+            delta: "think-1",
+          }),
+        )
+        send(
+          ephemeralEvent("session.text.delta", {
+            sessionID: "ses_order",
+            assistantMessageID: "msg_order",
+            ordinal: 1,
+            delta: "answer",
+          }),
+        )
+        send(
+          ephemeralEvent("session.reasoning.delta", {
+            sessionID: "ses_order",
+            assistantMessageID: "msg_order",
+            ordinal: 2,
+            delta: "think-2",
+          }),
+        )
+        send(
+          durableEvent("session.step.ended", {
+            sessionID: "ses_order",
+            assistantMessageID: "msg_order",
+            finish: "stop",
+            cost: 0,
+            tokens: tokens(),
+          }),
+        )
+        send(durableEvent("session.execution.succeeded", { sessionID: "ses_order" }))
+        await releaseSubmit.promise
+      },
+    })
+    const connection = {
+      sessionUpdate: async (update) => {
+        updates.push(update)
+        if (updates.length === 1) {
+          firstUpdate.resolve()
+          await releaseUpdate.promise
+        }
+        if (updates.length === 3) allUpdates.resolve()
+      },
+      requestPermission: async () => ({ outcome: { outcome: "cancelled" } }),
+    } satisfies Connection
+    const result = turn({ fixture, connection, sessionID: "ses_order", inputID: "input_order" })
+
+    try {
+      await withTimeout(firstUpdate.promise, "first ordered update was not delivered")
+      expect(updates).toHaveLength(1)
+      expect(fixture.requests.some((request) => request.path.includes("/message/"))).toBe(false)
+
+      releaseUpdate.resolve()
+      await withTimeout(allUpdates.promise, "ordered updates did not finish")
+      expect(await Promise.race([result.then(() => "resolved"), Promise.resolve("pending")])).toBe("pending")
+      expect(fixture.requests.some((request) => request.path.includes("/message/"))).toBe(false)
+
+      releaseSubmit.resolve()
+      const response = await withTimeout(result, "turn did not resolve after admission returned")
+
+      expect(
+        updates.map((item) => {
+          if (
+            item.update.sessionUpdate === "agent_message_chunk" ||
+            item.update.sessionUpdate === "agent_thought_chunk"
+          ) {
+            return [
+              item.update.sessionUpdate,
+              item.update.content.type === "text" ? item.update.content.text : undefined,
+            ]
+          }
+          return [item.update.sessionUpdate, undefined]
+        }),
+      ).toEqual([
+        ["agent_thought_chunk", "think-1"],
+        ["agent_message_chunk", "answer"],
+        ["agent_thought_chunk", "think-2"],
+      ])
+      expect(fixture.requests.at(-1)?.path).toBe("/api/session/ses_order/message/msg_order")
+      expect(response).toMatchObject({ stopReason: "end_turn", usage: { totalTokens: 2 } })
+    } finally {
+      releaseUpdate.resolve()
+      releaseSubmit.resolve()
+      await result.catch(() => undefined)
+      await fixture.stop()
+    }
+  })
+
+  test("streams tool pending, progress, success, and failure updates", async () => {
+    const updates: SessionUpdateParams[] = []
+    const fixture = createSseFixture({
+      onPrompt({ id, send }) {
+        send(durableEvent("session.input.promoted", { sessionID: "ses_tools", inputID: id }))
+        send(
+          durableEvent("session.tool.input.started", {
+            sessionID: "ses_tools",
+            assistantMessageID: "msg_tools",
+            callID: "call_ok",
+            name: "shell",
+          }),
+        )
+        send(
+          durableEvent("session.tool.called", {
+            sessionID: "ses_tools",
+            assistantMessageID: "msg_tools",
+            callID: "call_ok",
+            input: { command: "printf done", workdir: "sub" },
+            executed: false,
+          }),
+        )
+        send(
+          durableEvent("session.tool.progress", {
+            sessionID: "ses_tools",
+            assistantMessageID: "msg_tools",
+            callID: "call_ok",
+            structured: { phase: 1 },
+            content: [{ type: "text", text: "working" }],
+          }),
+        )
+        send(
+          durableEvent("session.tool.success", {
+            sessionID: "ses_tools",
+            assistantMessageID: "msg_tools",
+            callID: "call_ok",
+            structured: { exit: 0 },
+            content: [{ type: "text", text: "done" }],
+            result: { code: 0 },
+            executed: true,
+          }),
+        )
+        send(
+          durableEvent("session.tool.input.started", {
+            sessionID: "ses_tools",
+            assistantMessageID: "msg_tools",
+            callID: "call_fail",
+            name: "read",
+          }),
+        )
+        send(
+          durableEvent("session.tool.called", {
+            sessionID: "ses_tools",
+            assistantMessageID: "msg_tools",
+            callID: "call_fail",
+            input: { filePath: "/workspace/missing.ts" },
+            executed: false,
+          }),
+        )
+        send(
+          durableEvent("session.tool.progress", {
+            sessionID: "ses_tools",
+            assistantMessageID: "msg_tools",
+            callID: "call_fail",
+            structured: { bytes: 0 },
+            content: [{ type: "text", text: "opening" }],
+          }),
+        )
+        send(
+          durableEvent("session.tool.failed", {
+            sessionID: "ses_tools",
+            assistantMessageID: "msg_tools",
+            callID: "call_fail",
+            error: { type: "tool.error", message: "not found" },
+            executed: true,
+          }),
+        )
+        send(
+          durableEvent("session.step.ended", {
+            sessionID: "ses_tools",
+            assistantMessageID: "msg_tools",
+            finish: "stop",
+            cost: 0,
+            tokens: tokens(),
+          }),
+        )
+        send(durableEvent("session.execution.succeeded", { sessionID: "ses_tools" }))
+      },
+    })
+
+    try {
+      const response = await turn({
+        fixture,
+        connection: recordingConnection(updates),
+        sessionID: "ses_tools",
+        inputID: "input_tools",
+      })
+
+      expect(
+        updates.map((item) => [
+          item.update.sessionUpdate,
+          "status" in item.update ? item.update.status : undefined,
+          "toolCallId" in item.update ? item.update.toolCallId : undefined,
+        ]),
+      ).toEqual([
+        ["tool_call", "pending", "call_ok"],
+        ["tool_call_update", "in_progress", "call_ok"],
+        ["tool_call_update", "in_progress", "call_ok"],
+        ["tool_call_update", "completed", "call_ok"],
+        ["tool_call", "pending", "call_fail"],
+        ["tool_call_update", "in_progress", "call_fail"],
+        ["tool_call_update", "in_progress", "call_fail"],
+        ["tool_call_update", "failed", "call_fail"],
+      ])
+      expect(updates[1]?.update).toMatchObject({
+        title: "printf done",
+        kind: "execute",
+        locations: [{ path: resolve("/workspace", "sub") }],
+        rawInput: { command: "printf done", workdir: "sub" },
+      })
+      expect(updates[2]?.update).toMatchObject({
+        content: [{ type: "content", content: { type: "text", text: "working" } }],
+      })
+      expect(updates[3]?.update).toMatchObject({
+        content: [{ type: "content", content: { type: "text", text: "done" } }],
+        rawOutput: { structured: { exit: 0 }, result: { code: 0 } },
+      })
+      expect(updates[7]?.update).toMatchObject({
+        kind: "read",
+        locations: [{ path: "/workspace/missing.ts" }],
+        content: [
+          { type: "content", content: { type: "text", text: "opening" } },
+          { type: "content", content: { type: "text", text: "not found" } },
+        ],
+        rawOutput: { structured: { bytes: 0 }, error: "not found" },
+      })
+      expect(response.stopReason).toBe("end_turn")
+    } finally {
+      await fixture.stop()
+    }
+  })
+
+  test("replays user, text, reasoning, and tool messages in order", async () => {
+    const updates: SessionUpdateParams[] = []
+    const messages = replayFixtureMessages()
+    const connection = {
+      sessionUpdate: async (update) => {
+        updates.push(update)
+      },
+    } satisfies Pick<AgentSideConnection, "sessionUpdate">
+
+    await replayMessages(connection, "ses_replay", "/workspace", messages)
+
+    expect(updates.every((update) => update.sessionId === "ses_replay")).toBe(true)
+    expect(updates.map((item) => item.update.sessionUpdate)).toEqual([
+      "user_message_chunk",
+      "user_message_chunk",
+      "user_message_chunk",
+      "agent_message_chunk",
+      "agent_thought_chunk",
+      "tool_call",
+      "tool_call_update",
+      "tool_call",
+      "tool_call_update",
+      "tool_call",
+      "tool_call_update",
+      "tool_call",
+    ])
+    expect(updates[1]?.update).toMatchObject({
+      content: {
+        type: "resource_link",
+        uri: "file:///workspace/note.md",
+        name: "note.md",
+        mimeType: "text/markdown",
+      },
+    })
+    expect(updates[2]?.update).toMatchObject({
+      content: { type: "resource", resource: { mimeType: "text/plain", text: "hello" } },
+    })
+    expect(updates[6]?.update).toMatchObject({
+      toolCallId: "call_done",
+      status: "completed",
+      content: [
+        { type: "content", content: { type: "text", text: "done" } },
+        { type: "content", content: { type: "image", mimeType: "image/png", data: "AAAA" } },
+      ],
+      rawOutput: { structured: { exit: 0 }, result: { code: 0 } },
+    })
+    expect(updates[8]?.update).toMatchObject({
+      toolCallId: "call_running",
+      status: "in_progress",
+      title: "pwd",
+      locations: [{ path: "/workspace" }],
+    })
+    expect(updates[10]?.update).toMatchObject({
+      toolCallId: "call_failed",
+      status: "failed",
+      content: [
+        { type: "content", content: { type: "text", text: "partial" } },
+        { type: "content", content: { type: "text", text: "failed hard" } },
+      ],
+    })
+  })
+
+  test("continues replay after a session update callback rejects", async () => {
+    const attempts: Array<[string, string]> = []
+    const connection = {
+      sessionUpdate: async (params) => {
+        if (params.update.sessionUpdate !== "tool_call" && params.update.sessionUpdate !== "tool_call_update") return
+        attempts.push([params.update.toolCallId, params.update.sessionUpdate])
+        if (params.update.toolCallId === "call_first" && params.update.sessionUpdate === "tool_call_update") {
+          throw new Error("replay send failed")
+        }
+      },
+    } satisfies Pick<AgentSideConnection, "sessionUpdate">
+
+    await replayMessages(connection, "ses_replay_failure", "/workspace", [
+      replayToolMessage("call_first"),
+      replayToolMessage("call_after"),
+    ])
+
+    expect(attempts).toEqual([
+      ["call_first", "tool_call"],
+      ["call_first", "tool_call_update"],
+      ["call_after", "tool_call"],
+      ["call_after", "tool_call_update"],
+    ])
+  })
+
+  test("returns cancelled after an admitted turn is interrupted", async () => {
+    const submitted = Promise.withResolvers<void>()
+    const control: TurnControl = { cancelled: false, admission: new AbortController() }
+    const fixture = createSseFixture({
+      onPrompt({ id, send }) {
+        send(durableEvent("session.input.promoted", { sessionID: "ses_cancel", inputID: id }))
+      },
+      onInterrupt({ sessionID, send }) {
+        send(durableEvent("session.execution.interrupted", { sessionID, reason: "user" }))
+      },
+    })
+    const result = streamTurn({
+      client: fixture.client,
+      connection: recordingConnection([]),
+      sessionID: "ses_cancel",
+      cwd: "/workspace",
+      start: { type: "input", id: "input_cancel" },
+      control,
+      submit: async (signal) => {
+        await fixture.client.session.prompt(
+          { sessionID: "ses_cancel", id: "input_cancel", text: "cancel me" },
+          { signal },
+        )
+        submitted.resolve()
+      },
+    })
+
+    try {
+      await withTimeout(submitted.promise, "cancel test prompt was not admitted")
+      control.cancelled = true
+      control.admission.abort()
+      await fixture.client.session.interrupt({ sessionID: "ses_cancel" })
+
+      const response = await withTimeout(result, "cancelled turn did not terminate")
+      expect(response).toMatchObject({ stopReason: "cancelled" })
+      expect(fixture.requests.filter((request) => request.path.endsWith("/interrupt"))).toHaveLength(1)
+    } finally {
+      await fixture.stop()
+    }
+  })
+
+  test("returns cancelled when admission is aborted before promotion", async () => {
+    const submitted = Promise.withResolvers<void>()
+    const control: TurnControl = { cancelled: false, admission: new AbortController() }
+    const fixture = createSseFixture({
+      onPrompt({ signal }) {
+        submitted.resolve()
+        return new Promise<void>((resolve) => {
+          if (signal.aborted) return resolve()
+          signal.addEventListener("abort", () => resolve(), { once: true })
+        })
+      },
+    })
+    const result = streamTurn({
+      client: fixture.client,
+      connection: recordingConnection([]),
+      sessionID: "ses_cancel_admission",
+      cwd: "/workspace",
+      start: { type: "input", id: "input_cancel_admission" },
+      control,
+      submit: (signal) =>
+        fixture.client.session.prompt(
+          { sessionID: "ses_cancel_admission", id: "input_cancel_admission", text: "cancel me" },
+          { signal },
+        ),
+    })
+
+    try {
+      await withTimeout(submitted.promise, "cancel test prompt was not submitted")
+      control.cancelled = true
+      control.admission.abort()
+
+      const response = await withTimeout(result, "pre-admission cancellation did not terminate")
+      expect(response).toMatchObject({ stopReason: "cancelled" })
+      expect(fixture.requests.filter((request) => request.path.endsWith("/interrupt"))).toHaveLength(1)
+    } finally {
+      control.cancelled = true
+      control.admission.abort()
+      await result.catch(() => undefined)
+      await fixture.stop()
+    }
+  })
+
+  test("cancels unsupported session forms so execution can continue", async () => {
+    const fixture = createSseFixture({
+      onPrompt({ id, send }) {
+        send(durableEvent("session.input.promoted", { sessionID: "ses_form", inputID: id }))
+        send(
+          ephemeralEvent("form.created", {
+            form: {
+              id: "frm_question",
+              sessionID: "ses_form",
+              title: "Questions",
+              metadata: { kind: "question" },
+              fields: [{ key: "q0", title: "Choice", type: "string" }],
+            },
+          }),
+        )
+      },
+      onFormCancel({ sessionID, formID, send }) {
+        send(ephemeralEvent("form.cancelled", { sessionID, id: formID }))
+        send(durableEvent("session.execution.succeeded", { sessionID }))
+      },
+    })
+
+    try {
+      const response = await turn({
+        fixture,
+        connection: recordingConnection([]),
+        sessionID: "ses_form",
+        inputID: "input_form",
+      })
+
+      expect(response.stopReason).toBe("end_turn")
+      expect(
+        fixture.requests.some((request) => request.path === "/api/session/ses_form/form/frm_question/cancel"),
+      ).toBe(true)
+    } finally {
+      await fixture.stop()
+    }
+  })
+})
+
+function recordingConnection(updates: SessionUpdateParams[]) {
+  return {
+    sessionUpdate: async (update) => {
+      updates.push(update)
+    },
+    requestPermission: async () => ({ outcome: { outcome: "cancelled" } }),
+  } satisfies Connection
+}
+
+function turn(input: {
+  readonly fixture: Fixture
+  readonly connection: Connection
+  readonly sessionID: string
+  readonly inputID: string
+}) {
+  return streamTurn({
+    client: input.fixture.client,
+    connection: input.connection,
+    sessionID: input.sessionID,
+    cwd: "/workspace",
+    start: { type: "input", id: input.inputID },
+    userMessageID: `client_${input.inputID}`,
+    control: { cancelled: false, admission: new AbortController() },
+    submit: (signal) =>
+      input.fixture.client.session.prompt({ sessionID: input.sessionID, id: input.inputID, text: "hello" }, { signal }),
+  })
+}
+
+function tokens() {
+  return { input: 1, output: 1, reasoning: 0, cache: { read: 0, write: 0 } }
+}
+
+function replayFixtureMessages(): SessionMessageInfo[] {
+  return [
+    {
+      id: "msg_user",
+      type: "user",
+      text: "hello",
+      time: { created: 1 },
+      files: [
+        {
+          data: "",
+          mime: "text/markdown",
+          name: "note.md",
+          source: { type: "uri", uri: "file:///workspace/note.md" },
+        },
+        {
+          data: "aGVsbG8=",
+          mime: "text/plain",
+          name: "inline.txt",
+          source: { type: "inline" },
+        },
+      ],
+    },
+    {
+      id: "msg_assistant",
+      type: "assistant",
+      agent: "build",
+      model: { providerID: "test", id: "test-model" },
+      time: { created: 2, completed: 3 },
+      content: [
+        { type: "text", text: "answer" },
+        { type: "reasoning", text: "thinking" },
+        {
+          type: "tool",
+          id: "call_done",
+          name: "shell",
+          time: { created: 2, completed: 3 },
+          state: {
+            status: "completed",
+            input: { command: "printf done" },
+            structured: { exit: 0 },
+            content: [
+              { type: "text", text: "done" },
+              { type: "file", uri: "data:image/png;base64,AAAA", mime: "image/png", name: "image.png" },
+            ],
+            result: { code: 0 },
+          },
+        },
+        {
+          type: "tool",
+          id: "call_running",
+          name: "shell",
+          time: { created: 2, ran: 2 },
+          state: {
+            status: "running",
+            input: { command: "pwd" },
+            structured: {},
+            content: [{ type: "text", text: "/workspace" }],
+          },
+        },
+        {
+          type: "tool",
+          id: "call_failed",
+          name: "read",
+          time: { created: 2, completed: 3 },
+          state: {
+            status: "error",
+            input: { filePath: "/workspace/missing.ts" },
+            structured: { bytes: 0 },
+            content: [{ type: "text", text: "partial" }],
+            error: { type: "tool.error", message: "failed hard" },
+          },
+        },
+        {
+          type: "tool",
+          id: "call_streaming",
+          name: "shell",
+          time: { created: 2 },
+          state: { status: "streaming", input: '{"command":' },
+        },
+      ],
+    },
+  ]
+}
+
+function replayToolMessage(id: string) {
+  return {
+    id: `msg_${id}`,
+    type: "assistant",
+    agent: "build",
+    model: { providerID: "test", id: "test-model" },
+    time: { created: 1, completed: 2 },
+    content: [
+      {
+        type: "tool",
+        id,
+        name: "shell",
+        time: { created: 1, completed: 2 },
+        state: {
+          status: "completed",
+          input: { command: "printf done" },
+          structured: { exit: 0 },
+          content: [{ type: "text", text: "done" }],
+        },
+      },
+    ],
+  } satisfies SessionMessageInfo
+}

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

@@ -0,0 +1,124 @@
+import { expect, test } from "bun:test"
+import type { AgentSideConnection } from "@agentclientprotocol/sdk"
+import { OpenCode } from "@opencode-ai/client/promise"
+import { streamTurn } from "../../src/acp/event"
+
+test("acp prompt resolves after ordered turn updates", async () => {
+  const encoder = new TextEncoder()
+  let events: ReadableStreamDefaultController<Uint8Array> | undefined
+  const updates: Parameters<AgentSideConnection["sessionUpdate"]>[0][] = []
+  const server = Bun.serve({
+    port: 0,
+    async fetch(request) {
+      const url = new URL(request.url)
+      if (url.pathname === "/api/event") {
+        return new Response(
+          new ReadableStream<Uint8Array>({
+            start(controller) {
+              events = controller
+              send(controller, { id: "evt_connected", type: "server.connected", data: {} })
+            },
+          }),
+          { headers: { "content-type": "text/event-stream" } },
+        )
+      }
+      if (url.pathname === "/api/session/ses_test/prompt") {
+        const body: unknown = await request.json()
+        if (!body || typeof body !== "object") {
+          return new Response(null, { status: 400 })
+        }
+        const id = Reflect.get(body, "id")
+        if (typeof id !== "string") return new Response(null, { status: 400 })
+        queueMicrotask(() => {
+          if (!events) return
+          send(events, {
+            id: "evt_promoted",
+            created: 1,
+            type: "session.input.promoted",
+            data: { sessionID: "ses_test", inputID: id },
+          })
+          send(events, {
+            id: "evt_text",
+            created: 2,
+            type: "session.text.delta",
+            data: { sessionID: "ses_test", assistantMessageID: "msg_assistant", ordinal: 0, delta: "hello" },
+          })
+          send(events, {
+            id: "evt_step",
+            created: 3,
+            type: "session.step.ended",
+            data: {
+              sessionID: "ses_test",
+              assistantMessageID: "msg_assistant",
+              finish: "stop",
+              cost: 0,
+              tokens: { input: 1, output: 1, reasoning: 0, cache: { read: 0, write: 0 } },
+            },
+          })
+          send(events, {
+            id: "evt_done",
+            created: 4,
+            type: "session.execution.succeeded",
+            data: { sessionID: "ses_test" },
+          })
+        })
+        return Response.json({ data: {} })
+      }
+      if (url.pathname === "/api/session/ses_test/message/msg_assistant") {
+        return Response.json({
+          data: {
+            id: "msg_assistant",
+            type: "assistant",
+            agent: "build",
+            model: { providerID: "test", id: "test-model" },
+            content: [{ type: "text", text: "hello" }],
+            finish: "stop",
+            tokens: { input: 1, output: 1, reasoning: 0, cache: { read: 0, write: 0 } },
+            time: { created: 1, completed: 4 },
+          },
+        })
+      }
+      return new Response(null, { status: 404 })
+    },
+  })
+  const client = OpenCode.make({ baseUrl: server.url.toString() })
+
+  try {
+    const id = "msg_prompt"
+    const userMessageID = "client-message"
+    const response = await streamTurn({
+      client,
+      connection: {
+        sessionUpdate: async (update) => {
+          updates.push(update)
+        },
+        requestPermission: async () => ({ outcome: { outcome: "cancelled" } }),
+      },
+      sessionID: "ses_test",
+      cwd: "/workspace",
+      start: { type: "input", id },
+      userMessageID,
+      control: { cancelled: false, admission: new AbortController() },
+      submit: () => client.session.prompt({ sessionID: "ses_test", id, text: "hi" }),
+    })
+
+    expect(updates).toEqual([
+      {
+        sessionId: "ses_test",
+        update: {
+          sessionUpdate: "agent_message_chunk",
+          messageId: "msg_assistant",
+          content: { type: "text", text: "hello" },
+        },
+      },
+    ])
+    expect(response).toMatchObject({ stopReason: "end_turn", userMessageId: userMessageID, usage: { totalTokens: 2 } })
+  } finally {
+    events?.close()
+    await server.stop(true)
+  }
+
+  function send(controller: ReadableStreamDefaultController<Uint8Array>, event: unknown) {
+    controller.enqueue(encoder.encode(`data: ${JSON.stringify(event)}\n\n`))
+  }
+})

packages/cli/test/acp/initialize-auth.subprocess.test.ts

@@ -0,0 +1,49 @@
+import type { AuthenticateResponse, InitializeResponse } from "@agentclientprotocol/sdk"
+import { describe, expect, test } from "bun:test"
+import { createAcpFixture, expectOk, initialize } from "./subprocess"
+
+describe("acp initialize/auth subprocess", () => {
+  test("initialize responds with capabilities", async () => {
+    await using fixture = await createAcpFixture()
+    const initialized = await initialize(fixture.spawn())
+
+    expect(initialized.protocolVersion).toBe(1)
+    expect(initialized.agentCapabilities?.promptCapabilities?.embeddedContext).toBe(true)
+    expect(initialized.agentCapabilities?.promptCapabilities?.image).toBe(true)
+    expect(initialized.agentCapabilities?.mcpCapabilities?.http).toBe(true)
+    expect(initialized.agentCapabilities?.mcpCapabilities?.sse).toBe(false)
+    expect(initialized.agentCapabilities?.loadSession).toBe(true)
+    expect(initialized.agentCapabilities?.sessionCapabilities?.close).toEqual({})
+    expect(initialized.agentCapabilities?.sessionCapabilities?.fork).toEqual({})
+    expect(initialized.agentCapabilities?.sessionCapabilities?.list).toEqual({})
+    expect(initialized.agentCapabilities?.sessionCapabilities?.resume).toEqual({})
+    expect(initialized.agentInfo?.name).toBe("OpenCode")
+  }, 60_000)
+
+  test("auth negotiation is explicit and safe", async () => {
+    await using fixture = await createAcpFixture()
+    const secret = "subprocess-auth-secret"
+    const acp = fixture.spawn({ OPENCODE_AUTH_CONTENT: secret })
+    const initialized = await initialize(acp)
+
+    expect(initialized.authMethods?.[0]?.id).toBe("opencode-login")
+    expect(initialized.authMethods?.[0]?._meta?.["terminal-auth"]).toBeDefined()
+    expect(expectOk(await acp.request<AuthenticateResponse>("authenticate", { methodId: "opencode-login" }))).toEqual(
+      {},
+    )
+
+    const rejected = await acp.request<AuthenticateResponse>("authenticate", { methodId: "missing-auth-method" })
+    expect(rejected.error?.code).toBe(-32602)
+    expect(JSON.stringify(rejected.error)).not.toContain(secret)
+  }, 60_000)
+
+  test("initialize without terminal-auth metadata keeps auth command implicit", async () => {
+    await using fixture = await createAcpFixture()
+    const initialized = expectOk(
+      await fixture.spawn().request<InitializeResponse>("initialize", { protocolVersion: 1 }),
+    )
+
+    expect(initialized.authMethods?.[0]?.id).toBe("opencode-login")
+    expect(initialized.authMethods?.[0]?._meta?.["terminal-auth"]).toBeUndefined()
+  }, 60_000)
+})

packages/cli/test/acp/lifecycle.subprocess.test.ts

@@ -0,0 +1,85 @@
+import type {
+  CloseSessionResponse,
+  ListSessionsResponse,
+  LoadSessionResponse,
+  ResumeSessionResponse,
+} from "@agentclientprotocol/sdk"
+import { describe, expect, test } from "bun:test"
+import { createAcpFixture, expectOk, initialize, newSession, selectConfigOption } from "./subprocess"
+
+describe("acp lifecycle subprocess", () => {
+  test("stdin EOF exits cleanly", async () => {
+    await using fixture = await createAcpFixture()
+    expect(await fixture.spawn().close()).toBe(0)
+  }, 60_000)
+
+  test("close capability and close request", async () => {
+    await using fixture = await createAcpFixture()
+    const acp = fixture.spawn()
+    const initialized = await initialize(acp)
+    expect(initialized.agentCapabilities?.sessionCapabilities?.close).toEqual({})
+
+    const session = await newSession(acp, fixture.home)
+    expect(
+      expectOk(await acp.request<CloseSessionResponse>("session/close", { sessionId: session.sessionId })),
+    ).toEqual({})
+  }, 60_000)
+
+  test("new session succeeds on the first request", async () => {
+    await using fixture = await createAcpFixture()
+    const acp = fixture.spawn()
+    await initialize(acp)
+
+    expect((await newSession(acp, fixture.home)).sessionId).toStartWith("ses_")
+  }, 60_000)
+
+  test("loadSession capability and load request return session config options", async () => {
+    await using fixture = await createAcpFixture()
+    const acp = fixture.spawn()
+    const initialized = await initialize(acp)
+    expect(initialized.agentCapabilities?.loadSession).toBe(true)
+    const session = await newSession(acp, fixture.home)
+    const loaded = expectOk(
+      await acp.request<LoadSessionResponse>("session/load", {
+        cwd: fixture.home,
+        sessionId: session.sessionId,
+        mcpServers: [],
+      }),
+    )
+
+    expect(selectConfigOption(loaded.configOptions, "model")?.category).toBe("model")
+  }, 60_000)
+
+  test("list request includes a live ACP-created session", async () => {
+    await using fixture = await createAcpFixture()
+    const acp = fixture.spawn()
+    await initialize(acp)
+    const session = await newSession(acp, fixture.home)
+    const listed = expectOk(await acp.request<ListSessionsResponse>("session/list", { cwd: fixture.home }))
+
+    expect(listed.sessions.some((item) => item.sessionId === session.sessionId)).toBe(true)
+  }, 60_000)
+
+  test("resume capability advertisement", async () => {
+    await using fixture = await createAcpFixture()
+    const initialized = await initialize(fixture.spawn())
+
+    expect(initialized.agentCapabilities?.sessionCapabilities?.resume).toEqual({})
+  }, 60_000)
+
+  test("resume request returns session config options", async () => {
+    await using fixture = await createAcpFixture()
+    const acp = fixture.spawn()
+    await initialize(acp)
+    const session = await newSession(acp, fixture.home)
+    const resumed = expectOk(
+      await acp.request<ResumeSessionResponse>("session/resume", {
+        cwd: fixture.home,
+        sessionId: session.sessionId,
+        mcpServers: [],
+      }),
+    )
+
+    expect(selectConfigOption(resumed.configOptions, "model")?.category).toBe("model")
+  }, 60_000)
+})

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

@@ -0,0 +1,499 @@
+import { describe, expect, test } from "bun:test"
+import type { AgentSideConnection, RequestPermissionRequest, RequestPermissionResponse } from "@agentclientprotocol/sdk"
+import fs from "node:fs/promises"
+import os from "node:os"
+import path from "node:path"
+import { streamTurn } from "../../src/acp/event"
+import { createSseFixture, durableEvent, ephemeralEvent, withTimeout } from "./sse-fixture"
+
+type SessionUpdateParams = Parameters<AgentSideConnection["sessionUpdate"]>[0]
+type Connection = Pick<AgentSideConnection, "sessionUpdate" | "requestPermission"> &
+  Partial<Pick<AgentSideConnection, "writeTextFile">>
+type Fixture = ReturnType<typeof createSseFixture>
+
+describe("acp permission behavior", () => {
+  test("forwards allow-once and allow-always selections to the generated client", async () => {
+    const permissionRequests: RequestPermissionRequest[] = []
+    const fixture = createSseFixture({
+      onPrompt({ id, send }) {
+        send(durableEvent("session.input.promoted", { sessionID: "ses_allow", inputID: id }))
+        send(
+          permissionAsked("ses_allow", "perm_once", {
+            action: "shell",
+            metadata: { command: "printf hello" },
+            source: { type: "tool", messageID: "msg_allow", callID: "call_once" },
+          }),
+        )
+        send(
+          permissionAsked("ses_allow", "perm_always", {
+            action: "read",
+            metadata: { filePath: "/workspace/file.ts" },
+            source: { type: "tool", messageID: "msg_allow", callID: "call_always" },
+          }),
+        )
+        send(durableEvent("session.execution.succeeded", { sessionID: "ses_allow" }))
+      },
+    })
+    const connection = {
+      sessionUpdate: async () => {},
+      requestPermission: async (request) => {
+        permissionRequests.push(request)
+        return {
+          outcome: {
+            outcome: "selected",
+            optionId: request.toolCall.toolCallId === "call_once" ? "once" : "always",
+          },
+        }
+      },
+    } satisfies Connection
+
+    try {
+      await startTurn(fixture, connection, "ses_allow", "input_allow")
+
+      expect(permissionRequests[0]).toMatchObject({
+        sessionId: "ses_allow",
+        toolCall: {
+          toolCallId: "call_once",
+          status: "pending",
+          title: "printf hello",
+          kind: "execute",
+          locations: [{ path: "/workspace" }],
+          rawInput: { command: "printf hello", cwd: "/workspace" },
+        },
+        options: [
+          { optionId: "once", kind: "allow_once", name: "Allow once" },
+          { optionId: "always", kind: "allow_always", name: "Always allow" },
+          { optionId: "reject", kind: "reject_once", name: "Reject" },
+        ],
+      })
+      expect(permissionRequests[1]).toMatchObject({
+        sessionId: "ses_allow",
+        toolCall: {
+          toolCallId: "call_always",
+          status: "pending",
+          title: "/workspace/file.ts",
+          kind: "read",
+          locations: [{ path: "/workspace/file.ts" }],
+          rawInput: { filePath: "/workspace/file.ts" },
+        },
+      })
+      expect(permissionReplies(fixture)).toEqual([
+        ["perm_once", "once"],
+        ["perm_always", "always"],
+      ])
+    } finally {
+      await fixture.stop()
+    }
+  })
+
+  test("preserves external directory permission context", async () => {
+    const permissionRequests: RequestPermissionRequest[] = []
+    const fixture = createSseFixture({
+      onPrompt({ id, send }) {
+        send(durableEvent("session.input.promoted", { sessionID: "ses_external", inputID: id }))
+        send(
+          permissionAsked("ses_external", "perm_external", {
+            action: "external_directory",
+            metadata: {
+              command: "mkdir -p /tmp/outside",
+              description: "Create external directory",
+              directories: ["/tmp/outside"],
+              patterns: ["/tmp/outside/*"],
+            },
+          }),
+        )
+        send(durableEvent("session.execution.succeeded", { sessionID: "ses_external" }))
+      },
+    })
+    const connection = {
+      sessionUpdate: async () => {},
+      requestPermission: async (request) => {
+        permissionRequests.push(request)
+        return { outcome: { outcome: "selected", optionId: "once" } } as const
+      },
+    } satisfies Connection
+
+    try {
+      await startTurn(fixture, connection, "ses_external", "input_external")
+
+      expect(permissionRequests[0]?.toolCall).toMatchObject({
+        title: "Create external directory",
+        locations: [{ path: "/tmp/outside" }],
+        rawInput: {
+          command: "mkdir -p /tmp/outside",
+          description: "Create external directory",
+          directories: ["/tmp/outside"],
+          patterns: ["/tmp/outside/*"],
+        },
+      })
+    } finally {
+      await fixture.stop()
+    }
+  })
+
+  test("previews edits during approval and syncs the completed file", async () => {
+    const cwd = await fs.mkdtemp(path.join(os.tmpdir(), "opencode-acp-permission-"))
+    const file = path.join(cwd, "file.ts")
+    await fs.writeFile(file, "before")
+    const permissionRequests: RequestPermissionRequest[] = []
+    const writes: Parameters<AgentSideConnection["writeTextFile"]>[0][] = []
+    const fixture = createSseFixture({
+      onPrompt({ id, send }) {
+        send(durableEvent("session.input.promoted", { sessionID: "ses_edit", inputID: id }))
+        send(
+          durableEvent("session.tool.input.started", {
+            sessionID: "ses_edit",
+            assistantMessageID: "msg_edit",
+            callID: "call_edit",
+            name: "edit",
+          }),
+        )
+        send(
+          durableEvent("session.tool.called", {
+            sessionID: "ses_edit",
+            assistantMessageID: "msg_edit",
+            callID: "call_edit",
+            input: { path: "file.ts", oldString: "before", newString: "after" },
+            executed: false,
+          }),
+        )
+        send(
+          permissionAsked("ses_edit", "perm_edit", {
+            action: "edit",
+            source: { type: "tool", messageID: "msg_edit", callID: "call_edit" },
+          }),
+        )
+      },
+      async onPermissionReply({ send }) {
+        await fs.writeFile(file, "after")
+        send(
+          durableEvent("session.tool.success", {
+            sessionID: "ses_edit",
+            assistantMessageID: "msg_edit",
+            callID: "call_edit",
+            structured: { files: [{ file: "file.ts" }], replacements: 1 },
+            content: [{ type: "text", text: "edited" }],
+            executed: true,
+          }),
+        )
+        send(durableEvent("session.execution.succeeded", { sessionID: "ses_edit" }))
+      },
+    })
+    const connection = {
+      sessionUpdate: async () => {},
+      requestPermission: async (request) => {
+        permissionRequests.push(request)
+        return { outcome: { outcome: "selected", optionId: "once" } } as const
+      },
+      writeTextFile: async (request) => {
+        writes.push(request)
+        return {}
+      },
+    } satisfies Connection
+
+    try {
+      await startTurn(fixture, connection, "ses_edit", "input_edit", cwd)
+
+      expect(permissionRequests[0]?.toolCall).toMatchObject({
+        title: "file.ts",
+        kind: "edit",
+        locations: [{ path: "file.ts" }],
+        content: [{ type: "diff", path: "file.ts", oldText: "before", newText: "after" }],
+      })
+      expect(writes).toEqual([{ sessionId: "ses_edit", path: file, content: "after" }])
+    } finally {
+      await fixture.stop()
+      await fs.rm(cwd, { recursive: true, force: true })
+    }
+  })
+
+  test("previews and syncs each file in a patch", async () => {
+    const cwd = await fs.mkdtemp(path.join(os.tmpdir(), "opencode-acp-patch-permission-"))
+    await Promise.all([
+      fs.writeFile(path.join(cwd, "first.ts"), "one\n"),
+      fs.writeFile(path.join(cwd, "second.ts"), "alpha\n"),
+    ])
+    const patchText = [
+      "*** Begin Patch",
+      "*** Update File: first.ts",
+      "@@",
+      "-one",
+      "+two",
+      "*** Update File: second.ts",
+      "@@",
+      "-alpha",
+      "+beta",
+      "*** End Patch",
+    ].join("\n")
+    const permissionRequests: RequestPermissionRequest[] = []
+    const writes: Parameters<AgentSideConnection["writeTextFile"]>[0][] = []
+    const fixture = createSseFixture({
+      onPrompt({ id, send }) {
+        send(durableEvent("session.input.promoted", { sessionID: "ses_patch", inputID: id }))
+        send(
+          durableEvent("session.tool.input.started", {
+            sessionID: "ses_patch",
+            assistantMessageID: "msg_patch",
+            callID: "call_patch",
+            name: "patch",
+          }),
+        )
+        send(
+          durableEvent("session.tool.called", {
+            sessionID: "ses_patch",
+            assistantMessageID: "msg_patch",
+            callID: "call_patch",
+            input: { patchText },
+            executed: false,
+          }),
+        )
+        send(
+          permissionAsked("ses_patch", "perm_patch", {
+            action: "edit",
+            source: { type: "tool", messageID: "msg_patch", callID: "call_patch" },
+          }),
+        )
+      },
+      async onPermissionReply({ send }) {
+        await Promise.all([
+          fs.writeFile(path.join(cwd, "first.ts"), "two\n"),
+          fs.writeFile(path.join(cwd, "second.ts"), "beta\n"),
+        ])
+        send(
+          durableEvent("session.tool.success", {
+            sessionID: "ses_patch",
+            assistantMessageID: "msg_patch",
+            callID: "call_patch",
+            structured: { files: [{ file: "first.ts" }, { file: "second.ts" }] },
+            content: [{ type: "text", text: "patched" }],
+            executed: true,
+          }),
+        )
+        send(durableEvent("session.execution.succeeded", { sessionID: "ses_patch" }))
+      },
+    })
+    const connection = {
+      sessionUpdate: async () => {},
+      requestPermission: async (request) => {
+        permissionRequests.push(request)
+        return { outcome: { outcome: "selected", optionId: "once" } } as const
+      },
+      writeTextFile: async (request) => {
+        writes.push(request)
+        return {}
+      },
+    } satisfies Connection
+
+    try {
+      await startTurn(fixture, connection, "ses_patch", "input_patch", cwd)
+
+      expect(permissionRequests[0]?.toolCall).toMatchObject({
+        title: "2 files",
+        kind: "edit",
+        locations: [{ path: "first.ts" }, { path: "second.ts" }],
+        content: [
+          { type: "diff", path: "first.ts", oldText: "one\n", newText: "two\n" },
+          { type: "diff", path: "second.ts", oldText: "alpha\n", newText: "beta\n" },
+        ],
+      })
+      expect(writes.toSorted((a, b) => a.path.localeCompare(b.path))).toEqual([
+        { sessionId: "ses_patch", path: path.join(cwd, "first.ts"), content: "two\n" },
+        { sessionId: "ses_patch", path: path.join(cwd, "second.ts"), content: "beta\n" },
+      ])
+    } finally {
+      await fixture.stop()
+      await fs.rm(cwd, { recursive: true, force: true })
+    }
+  })
+
+  test("rejects explicit rejection, cancellation, and permission UI failure", async () => {
+    const fixture = createSseFixture({
+      onPrompt({ id, send }) {
+        send(durableEvent("session.input.promoted", { sessionID: "ses_reject", inputID: id }))
+        send(permissionAsked("ses_reject", "perm_selected_reject"))
+        send(permissionAsked("ses_reject", "perm_cancelled"))
+        send(permissionAsked("ses_reject", "perm_failed"))
+        send(durableEvent("session.execution.succeeded", { sessionID: "ses_reject" }))
+      },
+    })
+    const connection = {
+      sessionUpdate: async () => {},
+      requestPermission: async (request): Promise<RequestPermissionResponse> => {
+        if (request.toolCall.toolCallId === "perm_selected_reject") {
+          return { outcome: { outcome: "selected", optionId: "reject" } }
+        }
+        if (request.toolCall.toolCallId === "perm_cancelled") return { outcome: { outcome: "cancelled" } }
+        throw new Error("client permission UI failed")
+      },
+    } satisfies Connection
+
+    try {
+      const response = await startTurn(fixture, connection, "ses_reject", "input_reject")
+      expect(response).toMatchObject({ stopReason: "end_turn" })
+      expect(permissionReplies(fixture)).toEqual([
+        ["perm_selected_reject", "reject"],
+        ["perm_cancelled", "reject"],
+        ["perm_failed", "reject"],
+      ])
+    } finally {
+      await fixture.stop()
+    }
+  })
+
+  test("serializes permission requests and replies within one session", async () => {
+    const firstRequested = Promise.withResolvers<void>()
+    const releaseFirst = Promise.withResolvers<RequestPermissionResponse>()
+    const permissionRequests: RequestPermissionRequest[] = []
+    const fixture = createSseFixture({
+      onPrompt({ id, send }) {
+        send(durableEvent("session.input.promoted", { sessionID: "ses_serial", inputID: id }))
+        send(permissionAsked("ses_serial", "perm_1"))
+        send(permissionAsked("ses_serial", "perm_2"))
+        send(durableEvent("session.execution.succeeded", { sessionID: "ses_serial" }))
+      },
+    })
+    const connection = {
+      sessionUpdate: async () => {},
+      requestPermission: async (request) => {
+        permissionRequests.push(request)
+        if (request.toolCall.toolCallId === "perm_1") {
+          firstRequested.resolve()
+          return releaseFirst.promise
+        }
+        return { outcome: { outcome: "selected", optionId: "always" } } as const
+      },
+    } satisfies Connection
+    const result = startTurn(fixture, connection, "ses_serial", "input_serial")
+
+    try {
+      await withTimeout(firstRequested.promise, "first permission was not requested")
+      expect(permissionRequests.map((request) => request.toolCall.toolCallId)).toEqual(["perm_1"])
+      expect(permissionReplies(fixture)).toEqual([])
+
+      releaseFirst.resolve({ outcome: { outcome: "selected", optionId: "once" } })
+      await withTimeout(result, "serialized permission turn did not finish")
+
+      expect(permissionRequests.map((request) => request.toolCall.toolCallId)).toEqual(["perm_1", "perm_2"])
+      expect(permissionReplies(fixture)).toEqual([
+        ["perm_1", "once"],
+        ["perm_2", "always"],
+      ])
+    } finally {
+      releaseFirst.resolve({ outcome: { outcome: "cancelled" } })
+      await result.catch(() => undefined)
+      await fixture.stop()
+    }
+  })
+
+  test("does not let one session's blocked permission stall another session", async () => {
+    const blockedRequested = Promise.withResolvers<void>()
+    const releaseBlocked = Promise.withResolvers<RequestPermissionResponse>()
+    const promptIDs = new Map<string, string>()
+    const updates: SessionUpdateParams[] = []
+    const fixture = createSseFixture({
+      onPrompt({ sessionID, id, send }) {
+        promptIDs.set(sessionID, id)
+        if (promptIDs.size !== 2) return
+        const blockedID = promptIDs.get("ses_blocked")
+        const freeID = promptIDs.get("ses_free")
+        if (!blockedID || !freeID) throw new Error("both permission test prompts must be registered")
+        send(durableEvent("session.input.promoted", { sessionID: "ses_blocked", inputID: blockedID }))
+        send(durableEvent("session.input.promoted", { sessionID: "ses_free", inputID: freeID }))
+        send(permissionAsked("ses_blocked", "perm_blocked"))
+        send(
+          ephemeralEvent("session.text.delta", {
+            sessionID: "ses_free",
+            assistantMessageID: "msg_free",
+            ordinal: 0,
+            delta: "session B continued",
+          }),
+        )
+        send(
+          durableEvent("session.step.ended", {
+            sessionID: "ses_free",
+            assistantMessageID: "msg_free",
+            finish: "stop",
+            cost: 0,
+            tokens: { input: 1, output: 1, reasoning: 0, cache: { read: 0, write: 0 } },
+          }),
+        )
+        send(durableEvent("session.execution.succeeded", { sessionID: "ses_free" }))
+        send(durableEvent("session.execution.succeeded", { sessionID: "ses_blocked" }))
+      },
+    })
+    const connection = {
+      sessionUpdate: async (update) => {
+        updates.push(update)
+      },
+      requestPermission: async () => {
+        blockedRequested.resolve()
+        return releaseBlocked.promise
+      },
+    } satisfies Connection
+    const blocked = startTurn(fixture, connection, "ses_blocked", "input_blocked")
+    const free = startTurn(fixture, connection, "ses_free", "input_free")
+
+    try {
+      await withTimeout(blockedRequested.promise, "blocked permission was not requested")
+      const response = await withTimeout(free, "free session was stalled by another session's permission")
+      expect(response).toMatchObject({ stopReason: "end_turn" })
+      expect(updates).toContainEqual({
+        sessionId: "ses_free",
+        update: {
+          sessionUpdate: "agent_message_chunk",
+          messageId: "msg_free",
+          content: { type: "text", text: "session B continued" },
+        },
+      })
+      expect(permissionReplies(fixture)).toEqual([])
+
+      releaseBlocked.resolve({ outcome: { outcome: "selected", optionId: "once" } })
+      await withTimeout(blocked, "blocked session did not resume after permission selection")
+      expect(permissionReplies(fixture)).toEqual([["perm_blocked", "once"]])
+    } finally {
+      releaseBlocked.resolve({ outcome: { outcome: "cancelled" } })
+      await Promise.all([blocked.catch(() => undefined), free.catch(() => undefined)])
+      await fixture.stop()
+    }
+  })
+})
+
+function startTurn(fixture: Fixture, connection: Connection, sessionID: string, inputID: string, cwd = "/workspace") {
+  return streamTurn({
+    client: fixture.client,
+    connection,
+    sessionID,
+    cwd,
+    start: { type: "input", id: inputID },
+    control: { cancelled: false, admission: new AbortController() },
+    submit: (signal) => fixture.client.session.prompt({ sessionID, id: inputID, text: "hello" }, { signal }),
+  })
+}
+
+function permissionAsked(
+  sessionID: string,
+  id: string,
+  input: {
+    readonly action?: string
+    readonly metadata?: Record<string, unknown>
+    readonly source?: { readonly type: "tool"; readonly messageID: string; readonly callID: string }
+  } = {},
+) {
+  return ephemeralEvent("permission.v2.asked", {
+    id,
+    sessionID,
+    action: input.action ?? "shell",
+    resources: ["*"],
+    metadata: input.metadata ?? { command: "printf hello" },
+    ...(input.source ? { source: input.source } : {}),
+  })
+}
+
+function permissionReplies(fixture: Fixture) {
+  return fixture.requests.flatMap((request): Array<[string, string]> => {
+    const match = /^\/api\/session\/[^/]+\/permission\/([^/]+)\/reply$/.exec(request.path)
+    if (!match?.[1] || !request.body || typeof request.body !== "object") return []
+    const reply = Reflect.get(request.body, "reply")
+    return typeof reply === "string" ? [[decodeURIComponent(match[1]), reply]] : []
+  })
+}

packages/cli/test/acp/prompt-content.subprocess.test.ts

@@ -0,0 +1,62 @@
+import type { PromptResponse } from "@agentclientprotocol/sdk"
+import { describe, expect, test } from "bun:test"
+import path from "node:path"
+import { pathToFileURL } from "node:url"
+import { createAcpFixture, expectOk, initialize, newSession } from "./subprocess"
+
+const tinyPng = "iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAQAAAC1HAwCAAAAC0lEQVR42mP8/x8AAwMCAO+ip1sAAAAASUVORK5CYII="
+
+describe("acp prompt content subprocess", () => {
+  test("accepts embedded text resource image and file resource link prompt content", async () => {
+    await using fixture = await createAcpFixture()
+    await Bun.write(path.join(fixture.home, "README.md"), "# ACP content smoke\n")
+    const acp = fixture.spawn()
+    await initialize(acp)
+    const session = await newSession(acp, fixture.home)
+
+    expectOk(
+      await acp.request<PromptResponse>("session/prompt", {
+        sessionId: session.sessionId,
+        prompt: [
+          { type: "text", text: "Use this embedded resource." },
+          {
+            type: "resource",
+            resource: { uri: "file:///context.txt", mimeType: "text/plain", text: "embedded context" },
+          },
+        ],
+      }),
+    )
+
+    expectOk(
+      await acp.request<PromptResponse>("session/prompt", {
+        sessionId: session.sessionId,
+        prompt: [
+          { type: "text", text: "Use this image." },
+          {
+            type: "image",
+            mimeType: "image/png",
+            data: tinyPng,
+          },
+        ],
+      }),
+    )
+
+    const linked = expectOk(
+      await acp.request<PromptResponse>("session/prompt", {
+        sessionId: session.sessionId,
+        prompt: [
+          { type: "text", text: "Use this linked file." },
+          {
+            type: "resource_link",
+            uri: pathToFileURL(path.join(fixture.home, "README.md")).href,
+            name: "README.md",
+            mimeType: "text/markdown",
+          },
+        ],
+      }),
+    )
+
+    expect(linked.stopReason).toBe("end_turn")
+    expect(fixture.llm.requests.length).toBeGreaterThanOrEqual(3)
+  }, 60_000)
+})

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

@@ -0,0 +1,269 @@
+import { describe, expect, test } from "bun:test"
+import type { McpServer, SessionConfigOption } from "@agentclientprotocol/sdk"
+import { makeACPFixture, makeSession, secondModel, testModel } from "./service-fixture"
+
+describe("acp service directory behavior", () => {
+  test("creates sessions from a catalog shared by concurrent callers in the same cwd", async () => {
+    let created = 0
+    await using fixture = makeACPFixture({
+      fetch(request) {
+        if (request.method !== "POST" || request.path !== "/api/session") return undefined
+        created++
+        return Response.json({
+          data: makeSession(`ses_${created}`, { cwd: created <= 2 ? "/workspace" : "/other" }),
+        })
+      },
+    })
+
+    const first = await Promise.all([
+      fixture.service.newSession({ cwd: "/workspace", mcpServers: [] }),
+      fixture.service.newSession({ cwd: "/workspace", mcpServers: [] }),
+    ])
+    const other = await fixture.service.newSession({ cwd: "/other", mcpServers: [] })
+
+    expect(first.map((session) => session.sessionId).toSorted()).toEqual(["ses_1", "ses_2"])
+    expect(other.sessionId).toBe("ses_3")
+    expect(currentValue(first[0], "model")).toBe("test/test-model")
+    expect(currentValue(first[0], "mode")).toBe("build")
+    expect(
+      ["/api/model", "/api/model/default", "/api/agent", "/api/command", "/api/skill"].map((path) =>
+        fixture.requests
+          .filter((request) => request.path === path)
+          .map((request) => request.query["location[directory]"]),
+      ),
+    ).toEqual([
+      ["/workspace", "/other"],
+      ["/workspace", "/other"],
+      ["/workspace", "/other"],
+      ["/workspace", "/other"],
+      ["/workspace", "/other"],
+    ])
+    expect(
+      fixture.requests
+        .filter((request) => request.method === "POST" && request.path === "/api/session")
+        .map((request) => request.body),
+    ).toEqual([
+      {
+        agent: "build",
+        model: { providerID: "test", id: "test-model", variant: "default" },
+        location: { directory: "/workspace" },
+      },
+      {
+        agent: "build",
+        model: { providerID: "test", id: "test-model", variant: "default" },
+        location: { directory: "/workspace" },
+      },
+      {
+        agent: "build",
+        model: { providerID: "test", id: "test-model", variant: "default" },
+        location: { directory: "/other" },
+      },
+    ])
+    expect(
+      fixture.updates.map((item) =>
+        item.update.sessionUpdate === "available_commands_update"
+          ? item.update.availableCommands.map((command) => command.name)
+          : [],
+      ),
+    ).toEqual([
+      ["review", "verify"],
+      ["review", "verify"],
+      ["review", "verify"],
+    ])
+  })
+
+  test("does not cache a failed catalog load", async () => {
+    let modelCalls = 0
+    await using fixture = makeACPFixture({
+      fetch(request) {
+        if (request.path === "/api/model") {
+          modelCalls++
+          if (modelCalls === 1) {
+            return Response.json(
+              { name: "ModelsNotReadyError", data: { message: "catalog is warming" } },
+              { status: 503 },
+            )
+          }
+        }
+        if (request.method === "POST" && request.path === "/api/session") {
+          return Response.json({ data: makeSession("ses_retry") })
+        }
+        return undefined
+      },
+    })
+
+    const failure = await fixture.service
+      .newSession({ cwd: "/workspace", mcpServers: [] })
+      .catch((error: unknown) => error)
+    expect(failure).toMatchObject({ name: "ModelsNotReadyError" })
+    const retried = await fixture.service.newSession({ cwd: "/workspace", mcpServers: [] })
+
+    expect(retried.sessionId).toBe("ses_retry")
+    expect(modelCalls).toBe(2)
+  })
+
+  test("switches model, effort, and mode against the warm catalog", async () => {
+    await using fixture = makeACPFixture({
+      fetch(request) {
+        if (request.method === "POST" && request.path === "/api/session") {
+          return Response.json({ data: makeSession("ses_config") })
+        }
+        if (
+          request.method === "POST" &&
+          (request.path === "/api/session/ses_config/model" || request.path === "/api/session/ses_config/agent")
+        ) {
+          return new Response(null, { status: 204 })
+        }
+        return undefined
+      },
+    })
+    const session = await fixture.service.newSession({ cwd: "/workspace", mcpServers: [] })
+
+    const selectedModel = await fixture.service.setSessionConfigOption({
+      sessionId: session.sessionId,
+      configId: "model",
+      value: "test/second-model",
+    })
+    const selectedEffort = await fixture.service.setSessionConfigOption({
+      sessionId: session.sessionId,
+      configId: "effort",
+      value: "medium",
+    })
+    const selectedMode = await fixture.service.setSessionConfigOption({
+      sessionId: session.sessionId,
+      configId: "mode",
+      value: "plan",
+    })
+    await fixture.service.setSessionModel({ sessionId: session.sessionId, modelId: "test/test-model/high" })
+    await fixture.service.setSessionMode({ sessionId: session.sessionId, modeId: "build" })
+
+    expect(currentValue(selectedModel, "model")).toBe("test/second-model")
+    expect(currentValue(selectedModel, "effort")).toBe("low")
+    expect(currentValue(selectedEffort, "effort")).toBe("medium")
+    expect(currentValue(selectedMode, "mode")).toBe("plan")
+    expect(
+      fixture.requests
+        .filter((request) => request.path === "/api/session/ses_config/model")
+        .map((request) => request.body),
+    ).toEqual([
+      { model: { providerID: "test", id: secondModel.id } },
+      { model: { providerID: "test", id: secondModel.id, variant: "medium" } },
+      { model: { providerID: "test", id: testModel.id, variant: "high" } },
+    ])
+    expect(
+      fixture.requests
+        .filter((request) => request.path === "/api/session/ses_config/agent")
+        .map((request) => request.body),
+    ).toEqual([{ agent: "plan" }, { agent: "build" }])
+    expect(fixture.requests.filter((request) => request.path === "/api/model")).toHaveLength(1)
+
+    const invalidEffort = await fixture.service
+      .setSessionConfigOption({
+        sessionId: session.sessionId,
+        configId: "effort",
+        value: "maximum",
+      })
+      .catch((error: unknown) => error)
+    const invalidMode = await fixture.service
+      .setSessionConfigOption({
+        sessionId: session.sessionId,
+        configId: "mode",
+        value: "missing",
+      })
+      .catch((error: unknown) => error)
+    const invalidConfig = await fixture.service
+      .setSessionConfigOption({
+        sessionId: session.sessionId,
+        configId: "missing",
+        value: "value",
+      })
+      .catch((error: unknown) => error)
+    expect(invalidEffort).toMatchObject({ _tag: "ACPInvalidEffortError" })
+    expect(invalidMode).toMatchObject({ _tag: "ACPInvalidModeError" })
+    expect(invalidConfig).toMatchObject({ _tag: "ACPInvalidConfigOptionError" })
+  })
+
+  test("converts MCP configs and deduplicates registrations per session and config", async () => {
+    const local: McpServer = {
+      name: "tools",
+      command: "bun",
+      args: ["server.ts"],
+      env: [{ name: "TOKEN", value: "x" }],
+    }
+    const changed: McpServer = { ...local, args: ["changed.ts"] }
+    const remote: McpServer = {
+      type: "http",
+      name: "docs",
+      url: "https://example.com/mcp",
+      headers: [{ name: "Authorization", value: "Bearer x" }],
+    }
+    let created = 0
+    await using fixture = makeACPFixture({
+      fetch(request) {
+        if (request.method === "POST" && request.path === "/api/session") {
+          created++
+          return Response.json({ data: makeSession(`ses_${created}`) })
+        }
+        if (request.method === "GET" && request.path === "/api/session/ses_1") {
+          return Response.json({ data: makeSession("ses_1") })
+        }
+        if (request.method === "PUT" && request.path.startsWith("/api/mcp/")) {
+          return new Response(null, { status: 204 })
+        }
+        return undefined
+      },
+    })
+
+    await fixture.service.newSession({ cwd: "/workspace", mcpServers: [local, local, remote] })
+    await fixture.service.resumeSession({ cwd: "/workspace", sessionId: "ses_1", mcpServers: [local, remote] })
+    await fixture.service.resumeSession({ cwd: "/workspace", sessionId: "ses_1", mcpServers: [changed] })
+    await fixture.service.newSession({ cwd: "/workspace", mcpServers: [local] })
+
+    const adds = fixture.requests.filter((request) => request.method === "PUT" && request.path.startsWith("/api/mcp/"))
+    expect(adds).toHaveLength(4)
+    expect(adds.filter((request) => request.path === "/api/mcp/tools").map((request) => request.body)).toEqual([
+      {
+        config: {
+          type: "local",
+          command: ["bun", "server.ts"],
+          environment: { TOKEN: "x" },
+        },
+      },
+      {
+        config: {
+          type: "local",
+          command: ["bun", "changed.ts"],
+          environment: { TOKEN: "x" },
+        },
+      },
+      {
+        config: {
+          type: "local",
+          command: ["bun", "server.ts"],
+          environment: { TOKEN: "x" },
+        },
+      },
+    ])
+    expect(adds.find((request) => request.path === "/api/mcp/docs")?.body).toEqual({
+      config: {
+        type: "remote",
+        url: "https://example.com/mcp",
+        headers: { Authorization: "Bearer x" },
+        oauth: false,
+      },
+    })
+    expect(adds.map((request) => request.query)).toEqual([
+      { "location[directory]": "/workspace" },
+      { "location[directory]": "/workspace" },
+      { "location[directory]": "/workspace" },
+      { "location[directory]": "/workspace" },
+    ])
+  })
+})
+
+function currentValue(
+  result: { readonly configOptions?: readonly SessionConfigOption[] | null } | undefined,
+  id: string,
+) {
+  return result?.configOptions?.find((option) => option.id === id)?.currentValue
+}

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

@@ -0,0 +1,207 @@
+import type { AgentSideConnection } from "@agentclientprotocol/sdk"
+import {
+  OpenCode,
+  type AgentInfo,
+  type CommandInfo,
+  type ModelInfo,
+  type ModelRef,
+  type SessionInfo,
+  type SkillInfo,
+  type TokenUsageInfo,
+} from "@opencode-ai/client/promise"
+import { ACPService } from "../../src/acp/service"
+
+export type FixtureRequest = {
+  readonly method: string
+  readonly path: string
+  readonly query: Record<string, string>
+  readonly body: unknown
+}
+
+export type FixtureContext = {
+  readonly requests: FixtureRequest[]
+  send(event: unknown): void
+}
+
+type FixtureHandler = (
+  request: FixtureRequest,
+  context: FixtureContext,
+) => Response | undefined | Promise<Response | undefined>
+
+type FixtureOptions = {
+  readonly fetch?: FixtureHandler
+  readonly models?: readonly ModelInfo[]
+  readonly defaultModel?: ModelInfo
+  readonly agents?: readonly AgentInfo[]
+  readonly commands?: readonly CommandInfo[]
+  readonly skills?: readonly SkillInfo[]
+}
+
+export const testModel = {
+  id: "test-model",
+  modelID: "test-model",
+  providerID: "test",
+  name: "Test Model",
+  capabilities: { tools: true, input: ["text"], output: ["text"] },
+  variants: [{ id: "default" }, { id: "high" }],
+  time: { released: 0 },
+  cost: [],
+  status: "active",
+  enabled: true,
+  limit: { context: 100_000, output: 10_000 },
+} satisfies ModelInfo
+
+export const secondModel = {
+  id: "second-model",
+  modelID: "second-model",
+  providerID: "test",
+  name: "Second Model",
+  capabilities: { tools: true, input: ["text"], output: ["text"] },
+  variants: [{ id: "low" }, { id: "medium" }],
+  time: { released: 0 },
+  cost: [],
+  status: "active",
+  enabled: true,
+  limit: { context: 200_000, output: 20_000 },
+} satisfies ModelInfo
+
+export const buildAgent = {
+  id: "build",
+  name: "Build",
+  request: { settings: {}, headers: {}, body: {} },
+  mode: "primary",
+  hidden: false,
+  permissions: [],
+} satisfies AgentInfo
+
+export const planAgent = {
+  id: "plan",
+  name: "Plan",
+  description: "Plan first",
+  request: { settings: {}, headers: {}, body: {} },
+  mode: "primary",
+  hidden: false,
+  permissions: [],
+} satisfies AgentInfo
+
+export const reviewCommand = {
+  name: "review",
+  description: "Review changes",
+  template: "",
+} satisfies CommandInfo
+
+export const verifySkill = {
+  id: "verify",
+  name: "verify",
+  description: "Verify work",
+  slash: true,
+  location: "/skills/verify.md",
+  content: "verify",
+} satisfies SkillInfo
+
+export function makeSession(
+  id: string,
+  input: {
+    readonly cwd?: string
+    readonly agent?: string
+    readonly model?: ModelRef
+    readonly cost?: number
+    readonly tokens?: TokenUsageInfo
+    readonly time?: SessionInfo["time"]
+    readonly title?: string
+  } = {},
+): SessionInfo {
+  return {
+    id,
+    projectID: "global",
+    agent: input.agent ?? "build",
+    model: input.model ?? { providerID: "test", id: "test-model", variant: "default" },
+    cost: input.cost ?? 0,
+    tokens: input.tokens ?? { input: 0, output: 0, reasoning: 0, cache: { read: 0, write: 0 } },
+    time: input.time ?? { created: 0, updated: 0 },
+    title: input.title ?? `Session ${id}`,
+    location: { directory: input.cwd ?? "/workspace" },
+  }
+}
+
+export function makeACPFixture(options: FixtureOptions = {}) {
+  const requests: FixtureRequest[] = []
+  const updates: Parameters<AgentSideConnection["sessionUpdate"]>[0][] = []
+  const encoder = new TextEncoder()
+  let eventController: ReadableStreamDefaultController<Uint8Array> | undefined
+  const models = options.models ?? [testModel, secondModel]
+  const context: FixtureContext = {
+    requests,
+    send(event) {
+      if (!eventController) throw new Error("ACP fixture has no active event stream")
+      eventController.enqueue(encoder.encode(`data: ${JSON.stringify(event)}\n\n`))
+    },
+  }
+  const server = Bun.serve({
+    port: 0,
+    async fetch(raw) {
+      const url = new URL(raw.url)
+      const request: FixtureRequest = {
+        method: raw.method,
+        path: url.pathname,
+        query: Object.fromEntries(url.searchParams.entries()),
+        body: raw.method === "GET" || raw.method === "HEAD" ? undefined : await raw.json().catch(() => undefined),
+      }
+      requests.push(request)
+      const response = await options.fetch?.(request, context)
+      if (response) return response
+
+      const directory = request.query["location[directory]"] ?? "/workspace"
+      const location = { directory, project: { id: "global", directory } }
+      if (request.path === "/api/event") {
+        let controller: ReadableStreamDefaultController<Uint8Array> | undefined
+        return new Response(
+          new ReadableStream<Uint8Array>({
+            start(value) {
+              controller = value
+              eventController = value
+              context.send({ id: "evt_connected", type: "server.connected", data: {} })
+            },
+            cancel() {
+              if (eventController === controller) eventController = undefined
+            },
+          }),
+          { headers: { "content-type": "text/event-stream" } },
+        )
+      }
+      if (request.path === "/api/model") return Response.json({ location, data: models })
+      if (request.path === "/api/model/default") {
+        return Response.json({ location, data: options.defaultModel ?? models[0] ?? null })
+      }
+      if (request.path === "/api/agent") {
+        return Response.json({ location, data: options.agents ?? [buildAgent, planAgent] })
+      }
+      if (request.path === "/api/command") {
+        return Response.json({ location, data: options.commands ?? [reviewCommand] })
+      }
+      if (request.path === "/api/skill") {
+        return Response.json({ location, data: options.skills ?? [verifySkill] })
+      }
+      return new Response(null, { status: 404 })
+    },
+  })
+  const service = ACPService.make({
+    client: OpenCode.make({ baseUrl: server.url.toString() }),
+    connection: {
+      sessionUpdate: async (update) => {
+        updates.push(update)
+      },
+      requestPermission: async () => ({ outcome: { outcome: "cancelled" } }),
+    },
+  })
+
+  return {
+    service,
+    requests,
+    updates,
+    async [Symbol.asyncDispose]() {
+      eventController?.close()
+      await server.stop(true)
+    },
+  }
+}

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

@@ -0,0 +1,232 @@
+import { describe, expect, test } from "bun:test"
+import type { SessionConfigOption } from "@agentclientprotocol/sdk"
+import { makeACPFixture, makeSession, secondModel } from "./service-fixture"
+
+describe("acp service lifecycle", () => {
+  test("loads and forks with paginated replay while resume does not replay", async () => {
+    await using fixture = makeACPFixture({
+      fetch(request) {
+        if (request.method === "GET" && request.path === "/api/session/ses_loaded") {
+          return Response.json({
+            data: makeSession("ses_loaded", {
+              cwd: "/workspace",
+              agent: "plan",
+              model: { providerID: "test", id: secondModel.id, variant: "medium" },
+            }),
+          })
+        }
+        if (request.method === "GET" && request.path === "/api/session/ses_resume") {
+          return Response.json({
+            data: makeSession("ses_resume", {
+              cwd: "/workspace",
+              agent: "plan",
+              model: { providerID: "test", id: secondModel.id, variant: "low" },
+            }),
+          })
+        }
+        if (request.method === "POST" && request.path === "/api/session/ses_loaded/fork") {
+          return Response.json({
+            data: makeSession("ses_fork", {
+              cwd: "/workspace",
+              agent: "plan",
+              model: { providerID: "test", id: secondModel.id, variant: "medium" },
+            }),
+          })
+        }
+        if (request.method === "GET" && request.path === "/api/session/ses_loaded/message") {
+          if (request.query.cursor === "messages-2") {
+            return Response.json({
+              data: [
+                {
+                  id: "msg_assistant",
+                  type: "assistant",
+                  content: [{ type: "text", text: "hi there" }],
+                },
+              ],
+              cursor: {},
+            })
+          }
+          return Response.json({
+            data: [{ id: "msg_user", type: "user", text: "hello", time: { created: 1 } }],
+            cursor: { next: "messages-2" },
+          })
+        }
+        if (request.method === "GET" && request.path === "/api/session/ses_fork/message") {
+          return Response.json({
+            data: [{ id: "msg_fork", type: "user", text: "forked", time: { created: 2 } }],
+            cursor: {},
+          })
+        }
+        return undefined
+      },
+    })
+
+    const loaded = await fixture.service.loadSession({
+      cwd: "/ignored",
+      sessionId: "ses_loaded",
+      mcpServers: [],
+    })
+    const resumed = await fixture.service.resumeSession({
+      cwd: "/ignored",
+      sessionId: "ses_resume",
+      mcpServers: [],
+    })
+    const forked = await fixture.service.forkSession({
+      cwd: "/ignored",
+      sessionId: "ses_loaded",
+      mcpServers: [],
+    })
+
+    expect(currentValue(loaded, "model")).toBe("test/second-model")
+    expect(currentValue(loaded, "effort")).toBe("medium")
+    expect(currentValue(loaded, "mode")).toBe("plan")
+    expect(currentValue(resumed, "effort")).toBe("low")
+    expect(forked.sessionId).toBe("ses_fork")
+    expect(currentValue(forked, "effort")).toBe("medium")
+    expect(
+      fixture.updates.filter(
+        (item) =>
+          item.update.sessionUpdate === "user_message_chunk" || item.update.sessionUpdate === "agent_message_chunk",
+      ),
+    ).toEqual([
+      {
+        sessionId: "ses_loaded",
+        update: {
+          sessionUpdate: "user_message_chunk",
+          messageId: "msg_user",
+          content: { type: "text", text: "hello" },
+        },
+      },
+      {
+        sessionId: "ses_loaded",
+        update: {
+          sessionUpdate: "agent_message_chunk",
+          messageId: "msg_assistant",
+          content: { type: "text", text: "hi there" },
+        },
+      },
+      {
+        sessionId: "ses_fork",
+        update: {
+          sessionUpdate: "user_message_chunk",
+          messageId: "msg_fork",
+          content: { type: "text", text: "forked" },
+        },
+      },
+    ])
+    expect(
+      fixture.requests
+        .filter((request) => request.path.endsWith("/message"))
+        .map((request) => ({ path: request.path, query: request.query })),
+    ).toEqual([
+      {
+        path: "/api/session/ses_loaded/message",
+        query: { limit: "200", order: "asc" },
+      },
+      {
+        path: "/api/session/ses_loaded/message",
+        query: { limit: "200", cursor: "messages-2" },
+      },
+      {
+        path: "/api/session/ses_fork/message",
+        query: { limit: "200", order: "asc" },
+      },
+    ])
+    expect(fixture.requests).toContainEqual({
+      method: "POST",
+      path: "/api/session/ses_loaded/fork",
+      query: {},
+      body: {},
+    })
+  })
+
+  test("lists server-backed pages and forwards cwd and cursor", async () => {
+    const firstPage = Array.from({ length: 100 }, (_, index) =>
+      makeSession(`ses_${100 - index}`, {
+        cwd: "/workspace",
+        time: { created: index, updated: 100_000 - index },
+        title: `Session ${100 - index}`,
+      }),
+    )
+    await using fixture = makeACPFixture({
+      fetch(request) {
+        if (request.method !== "GET" || request.path !== "/api/session") return undefined
+        if (request.query.cursor === "page-2") {
+          return Response.json({
+            data: [makeSession("ses_0", { cwd: "/workspace", time: { created: 0, updated: 1 } })],
+            cursor: {},
+          })
+        }
+        return Response.json({ data: firstPage, cursor: { next: "page-2" } })
+      },
+    })
+
+    const first = await fixture.service.listSessions({ cwd: "/workspace" })
+    const second = await fixture.service.listSessions({ cwd: "/workspace", cursor: first.nextCursor })
+
+    expect(first.sessions).toHaveLength(100)
+    expect(first.sessions[0]).toEqual({
+      sessionId: "ses_100",
+      cwd: "/workspace",
+      title: "Session 100",
+      updatedAt: new Date(100_000).toISOString(),
+    })
+    expect(first.nextCursor).toBe("page-2")
+    expect(second.sessions.map((session) => session.sessionId)).toEqual(["ses_0"])
+    expect(second.nextCursor).toBeUndefined()
+    expect(
+      fixture.requests.filter((request) => request.path === "/api/session").map((request) => request.query),
+    ).toEqual([
+      { limit: "100", order: "desc", directory: "/workspace" },
+      { limit: "100", order: "desc", directory: "/workspace", cursor: "page-2" },
+    ])
+  })
+
+  test("cancel preserves the attachment while close removes it and interrupts best-effort", async () => {
+    await using fixture = makeACPFixture({
+      fetch(request) {
+        if (request.method === "POST" && request.path === "/api/session") {
+          return Response.json({ data: makeSession("ses_lifecycle") })
+        }
+        if (request.method === "POST" && request.path === "/api/session/ses_lifecycle/model") {
+          return new Response(null, { status: 204 })
+        }
+        if (request.method === "POST" && request.path.endsWith("/interrupt")) {
+          return new Response(null, { status: 500 })
+        }
+        return undefined
+      },
+    })
+    const created = await fixture.service.newSession({ cwd: "/workspace", mcpServers: [] })
+
+    await fixture.service.cancel({ sessionId: created.sessionId })
+    const updated = await fixture.service.setSessionConfigOption({
+      sessionId: created.sessionId,
+      configId: "effort",
+      value: "high",
+    })
+
+    expect(currentValue(updated, "effort")).toBe("high")
+    expect(await fixture.service.closeSession({ sessionId: created.sessionId })).toEqual({})
+    const missing = await fixture.service
+      .setSessionConfigOption({
+        sessionId: created.sessionId,
+        configId: "effort",
+        value: "default",
+      })
+      .catch((error: unknown) => error)
+    expect(missing).toMatchObject({ _tag: "ACPSessionNotFoundError", sessionId: created.sessionId })
+    expect(await fixture.service.closeSession({ sessionId: "missing" })).toEqual({})
+    expect(
+      fixture.requests.filter((request) => request.path.endsWith("/interrupt")).map((request) => request.path),
+    ).toEqual([
+      "/api/session/ses_lifecycle/interrupt",
+      "/api/session/ses_lifecycle/interrupt",
+      "/api/session/missing/interrupt",
+    ])
+  })
+})
+
+function currentValue(result: { readonly configOptions?: readonly SessionConfigOption[] | null }, id: string) {
+  return result.configOptions?.find((option) => option.id === id)?.currentValue
+}

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

@@ -0,0 +1,264 @@
+import { describe, expect, test } from "bun:test"
+import { makeACPFixture, makeSession, secondModel, type FixtureContext, type FixtureRequest } from "./service-fixture"
+
+describe("acp service prompt routing and usage", () => {
+  test("routes slash commands, skills, and compact through their session endpoints", async () => {
+    await using fixture = makeACPFixture({
+      fetch(request, context) {
+        if (request.method === "POST" && request.path === "/api/session") {
+          return Response.json({ data: makeSession("ses_routes") })
+        }
+        if (request.method === "GET" && request.path === "/api/session/ses_routes") {
+          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_${id}`,
+            type: "session.input.promoted",
+            data: { sessionID: "ses_routes", inputID: id },
+          })
+          return Response.json({ data: {} })
+        }
+        if (request.method === "POST" && request.path === "/api/session/ses_routes/skill") {
+          const id = requestID(request)
+          completeTurn(context, "ses_routes", {
+            id: id.replace(/^msg_/, "evt_"),
+            type: "session.skill.activated",
+            data: { sessionID: "ses_routes", skill: "verify" },
+          })
+          return new Response(null, { status: 204 })
+        }
+        if (request.method === "POST" && request.path === "/api/session/ses_routes/compact") {
+          const id = requestID(request)
+          completeTurn(context, "ses_routes", {
+            id: `evt_${id}`,
+            type: "session.compaction.admitted",
+            data: { sessionID: "ses_routes", inputID: id },
+          })
+          return Response.json({ data: {} })
+        }
+        return undefined
+      },
+    })
+    const session = await fixture.service.newSession({ cwd: "/workspace", mcpServers: [] })
+
+    const commandResult = await fixture.service.prompt({
+      sessionId: session.sessionId,
+      messageId: "client-command",
+      prompt: [{ type: "text", text: "/review now" }],
+    })
+    const skillResult = await fixture.service.prompt({
+      sessionId: session.sessionId,
+      messageId: "client-skill",
+      prompt: [{ type: "text", text: "/verify" }],
+    })
+    const compactResult = await fixture.service.prompt({
+      sessionId: session.sessionId,
+      messageId: "client-compact",
+      prompt: [{ type: "text", text: "/compact" }],
+    })
+
+    expect([commandResult.stopReason, skillResult.stopReason, compactResult.stopReason]).toEqual([
+      "end_turn",
+      "end_turn",
+      "end_turn",
+    ])
+    const command = fixture.requests.find((request) => request.path === "/api/session/ses_routes/command")
+    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",
+      files: [],
+      delivery: "steer",
+    })
+    expect(skill?.body).toMatchObject({ id: expect.any(String), skill: "verify" })
+    expect(compact?.body).toMatchObject({ id: expect.any(String) })
+    expect(fixture.requests.some((request) => request.path === "/api/session/ses_routes/prompt")).toBe(false)
+  })
+
+  test("returns turn usage and publishes current context usage with cumulative session cost", async () => {
+    const assistantTokens = {
+      input: 100,
+      output: 40,
+      reasoning: 7,
+      cache: { read: 11, write: 13 },
+    }
+    await using fixture = makeACPFixture({
+      fetch(request, context) {
+        if (request.method === "POST" && request.path === "/api/session") {
+          return Response.json({ data: makeSession("ses_usage") })
+        }
+        if (request.method === "POST" && request.path === "/api/session/ses_usage/model") {
+          return new Response(null, { status: 204 })
+        }
+        if (request.method === "POST" && request.path === "/api/session/ses_usage/prompt") {
+          const id = requestID(request)
+          context.send({
+            id: `evt_${id}`,
+            type: "session.input.promoted",
+            data: { sessionID: "ses_usage", inputID: id },
+          })
+          context.send({
+            id: "evt_step",
+            type: "session.step.ended",
+            data: {
+              sessionID: "ses_usage",
+              assistantMessageID: "msg_assistant",
+              finish: "stop",
+              cost: 0.5,
+              tokens: assistantTokens,
+            },
+          })
+          context.send({
+            id: "evt_done",
+            type: "session.execution.succeeded",
+            data: { sessionID: "ses_usage" },
+          })
+          return Response.json({ data: {} })
+        }
+        if (request.method === "GET" && request.path === "/api/session/ses_usage/message/msg_assistant") {
+          return Response.json({
+            data: {
+              id: "msg_assistant",
+              type: "assistant",
+              agent: "build",
+              model: { providerID: "test", id: secondModel.id },
+              content: [{ type: "text", text: "done" }],
+              finish: "stop",
+              tokens: assistantTokens,
+              time: { created: 1, completed: 2 },
+            },
+          })
+        }
+        if (request.method === "GET" && request.path === "/api/session/ses_usage") {
+          return Response.json({
+            data: makeSession("ses_usage", {
+              model: { providerID: "test", id: secondModel.id },
+              cost: 3.5,
+              tokens: { input: 120, output: 50, reasoning: 8, cache: { read: 30, write: 4 } },
+            }),
+          })
+        }
+        return undefined
+      },
+    })
+    const session = await fixture.service.newSession({ cwd: "/workspace", mcpServers: [] })
+    await fixture.service.setSessionConfigOption({
+      sessionId: session.sessionId,
+      configId: "model",
+      value: "test/second-model",
+    })
+
+    const response = await fixture.service.prompt({
+      sessionId: session.sessionId,
+      messageId: "client-message",
+      prompt: [{ type: "text", text: "hello" }],
+    })
+
+    expect(response).toEqual({
+      stopReason: "end_turn",
+      userMessageId: "client-message",
+      usage: {
+        inputTokens: 100,
+        outputTokens: 40,
+        thoughtTokens: 7,
+        cachedReadTokens: 11,
+        cachedWriteTokens: 13,
+        totalTokens: 171,
+      },
+      _meta: {},
+    })
+    expect(fixture.updates.filter((item) => item.update.sessionUpdate === "usage_update")).toEqual([
+      {
+        sessionId: "ses_usage",
+        update: {
+          sessionUpdate: "usage_update",
+          used: 171,
+          size: 200_000,
+          cost: { amount: 3.5, currency: "USD" },
+        },
+      },
+    ])
+  })
+
+  test("does not fail a completed prompt when the usage refresh fails", async () => {
+    await using fixture = makeACPFixture({
+      fetch(request, context) {
+        if (request.method === "POST" && request.path === "/api/session") {
+          return Response.json({ data: makeSession("ses_usage_failure") })
+        }
+        if (request.method === "POST" && request.path === "/api/session/ses_usage_failure/prompt") {
+          const id = requestID(request)
+          context.send({
+            id: `evt_${id}`,
+            type: "session.input.promoted",
+            data: { sessionID: "ses_usage_failure", inputID: id },
+          })
+          context.send({
+            id: "evt_step_failure",
+            type: "session.step.ended",
+            data: {
+              sessionID: "ses_usage_failure",
+              assistantMessageID: "msg_usage_failure",
+              finish: "stop",
+              cost: 0,
+              tokens: { input: 3, output: 2, reasoning: 0, cache: { read: 0, write: 0 } },
+            },
+          })
+          context.send({
+            id: "evt_done_failure",
+            type: "session.execution.succeeded",
+            data: { sessionID: "ses_usage_failure" },
+          })
+          return Response.json({ data: {} })
+        }
+        if (request.method === "GET" && request.path === "/api/session/ses_usage_failure/message/msg_usage_failure") {
+          return Response.json({
+            data: {
+              id: "msg_usage_failure",
+              type: "assistant",
+              agent: "build",
+              model: { providerID: "test", id: "test-model" },
+              content: [],
+              finish: "stop",
+              tokens: { input: 3, output: 2, reasoning: 0, cache: { read: 0, write: 0 } },
+              time: { created: 1, completed: 2 },
+            },
+          })
+        }
+        if (request.method === "GET" && request.path === "/api/session/ses_usage_failure") {
+          return new Response(null, { status: 500 })
+        }
+        return undefined
+      },
+    })
+    const session = await fixture.service.newSession({ cwd: "/workspace", mcpServers: [] })
+
+    const response = await fixture.service.prompt({
+      sessionId: session.sessionId,
+      prompt: [{ type: "text", text: "hello" }],
+    })
+
+    expect(response.stopReason).toBe("end_turn")
+    expect(fixture.updates.some((item) => item.update.sessionUpdate === "usage_update")).toBe(false)
+  })
+})
+
+function requestID(request: FixtureRequest) {
+  if (!request.body || typeof request.body !== "object") throw new Error(`missing body for ${request.path}`)
+  const id = Reflect.get(request.body, "id")
+  if (typeof id !== "string") throw new Error(`missing prompt id for ${request.path}`)
+  return id
+}
+
+function completeTurn(context: FixtureContext, sessionID: string, start: unknown) {
+  context.send(start)
+  context.send({
+    id: `evt_done_${sessionID}`,
+    type: "session.execution.succeeded",
+    data: { sessionID },
+  })
+}

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

@@ -0,0 +1,110 @@
+import { describe, expect, test } from "bun:test"
+import type { AgentSideConnection } from "@agentclientprotocol/sdk"
+import { OpenCode } from "@opencode-ai/client/promise"
+import { ACPService } from "../../src/acp/service"
+
+describe("acp service", () => {
+  test("creates a v2 session, registers mcp, and publishes commands", async () => {
+    const requests: Array<{ method: string; path: string; body?: unknown }> = []
+    const updates: Parameters<AgentSideConnection["sessionUpdate"]>[0][] = []
+    const server = Bun.serve({
+      port: 0,
+      async fetch(request) {
+        const url = new URL(request.url)
+        requests.push({
+          method: request.method,
+          path: url.pathname,
+          body: request.method === "GET" ? undefined : await request.json().catch(() => undefined),
+        })
+        const location = { directory: "/workspace", project: { id: "global", directory: "/workspace" } }
+        if (url.pathname === "/api/model") return Response.json({ location, data: [model] })
+        if (url.pathname === "/api/model/default") return Response.json({ location, data: model })
+        if (url.pathname === "/api/agent") return Response.json({ location, data: [agent] })
+        if (url.pathname === "/api/command")
+          return Response.json({ location, data: [{ name: "review", template: "" }] })
+        if (url.pathname === "/api/skill") return Response.json({ location, data: [skill] })
+        if (url.pathname === "/api/session" && request.method === "POST") return Response.json({ data: session })
+        if (url.pathname === "/api/mcp/docs" && request.method === "PUT") return new Response(null, { status: 204 })
+        return new Response(null, { status: 404 })
+      },
+    })
+    const service = ACPService.make({
+      client: OpenCode.make({ baseUrl: server.url.toString() }),
+      connection: {
+        sessionUpdate: async (update) => {
+          updates.push(update)
+        },
+        requestPermission: async () => ({ outcome: { outcome: "cancelled" } }),
+      },
+    })
+
+    try {
+      const result = await service.newSession({
+        cwd: "/workspace",
+        mcpServers: [{ name: "docs", command: "bun", args: ["docs.ts"], env: [{ name: "TOKEN", value: "x" }] }],
+      })
+      expect(result.sessionId).toBe("ses_acp")
+      expect(result.configOptions?.map((option) => option.id)).toEqual(["model", "effort", "mode"])
+      expect(requests).toContainEqual({
+        method: "PUT",
+        path: "/api/mcp/docs",
+        body: {
+          config: { type: "local", command: ["bun", "docs.ts"], environment: { TOKEN: "x" } },
+        },
+      })
+      expect(updates.at(-1)).toMatchObject({
+        sessionId: "ses_acp",
+        update: {
+          sessionUpdate: "available_commands_update",
+          availableCommands: [{ name: "review" }, { name: "verify", description: "Verify work" }],
+        },
+      })
+    } finally {
+      await server.stop(true)
+    }
+  })
+})
+
+const model = {
+  id: "test-model",
+  modelID: "test-model",
+  providerID: "test",
+  name: "Test Model",
+  capabilities: { tools: true, input: ["text"], output: ["text"] },
+  variants: [{ id: "default" }, { id: "high" }],
+  time: { released: 0 },
+  cost: [],
+  status: "active" as const,
+  enabled: true,
+  limit: { context: 100_000, output: 10_000 },
+}
+
+const agent = {
+  id: "build",
+  name: "Build",
+  request: { settings: {}, headers: {}, body: {} },
+  mode: "primary" as const,
+  hidden: false,
+  permissions: [],
+}
+
+const skill = {
+  id: "verify",
+  name: "verify",
+  description: "Verify work",
+  slash: true,
+  location: "/skills/verify.md",
+  content: "verify",
+}
+
+const session = {
+  id: "ses_acp",
+  projectID: "global",
+  agent: "build",
+  model: { providerID: "test", id: "test-model", variant: "default" },
+  cost: 0,
+  tokens: { input: 0, output: 0, reasoning: 0, cache: { read: 0, write: 0 } },
+  time: { created: 0, updated: 0 },
+  title: "New session",
+  location: { directory: "/workspace" },
+}

packages/cli/test/acp/skills.subprocess.test.ts

@@ -0,0 +1,24 @@
+import type { SessionNotification } from "@agentclientprotocol/sdk"
+import { describe, expect, test } from "bun:test"
+import { createAcpFixture, initialize, newSession, verifierSkill } from "./subprocess"
+
+describe("acp skills subprocess", () => {
+  test("skill slash command appears through available_commands_update", async () => {
+    await using fixture = await createAcpFixture({ skill: verifierSkill })
+    const acp = fixture.spawn()
+    await initialize(acp)
+    const session = await newSession(acp, fixture.home)
+
+    const update = await acp.waitForNotification<SessionNotification>(
+      "session/update",
+      (params) =>
+        params.sessionId === session.sessionId &&
+        params.update.sessionUpdate === "available_commands_update" &&
+        params.update.availableCommands.some(
+          (command) => command.name === "verifier-skill" && command.description.length > 0,
+        ),
+    )
+
+    expect(update.params.sessionId).toBe(session.sessionId)
+  }, 60_000)
+})

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

@@ -0,0 +1,207 @@
+import { OpenCode, type OpenCodeEvent, type SessionMessageInfo } from "@opencode-ai/client/promise"
+
+type DurableEvent = Extract<OpenCodeEvent, { durable: unknown }>
+type EphemeralEvent = Exclude<OpenCodeEvent, DurableEvent>
+
+type RequestRecord = {
+  readonly method: string
+  readonly path: string
+  readonly body?: unknown
+}
+
+type FixtureOptions = {
+  readonly onPrompt?: (input: {
+    readonly sessionID: string
+    readonly id: string
+    readonly body: unknown
+    readonly signal: AbortSignal
+    readonly send: (event: unknown) => void
+  }) => void | Promise<void>
+  readonly onInterrupt?: (input: {
+    readonly sessionID: string
+    readonly send: (event: unknown) => void
+  }) => void | Promise<void>
+  readonly onPermissionReply?: (input: {
+    readonly sessionID: string
+    readonly requestID: string
+    readonly reply: string
+    readonly body: unknown
+    readonly send: (event: unknown) => void
+  }) => void | Promise<void>
+  readonly onFormCancel?: (input: {
+    readonly sessionID: string
+    readonly formID: string
+    readonly send: (event: unknown) => void
+  }) => void | Promise<void>
+}
+
+const ids = { next: 0 }
+
+export function durableEvent<Type extends DurableEvent["type"]>(
+  type: Type,
+  data: Extract<DurableEvent, { type: Type }>["data"],
+) {
+  ids.next++
+  return {
+    id: `evt_${ids.next}`,
+    created: ids.next,
+    type,
+    durable: { aggregateID: "test", seq: ids.next, version: 1 },
+    data,
+  }
+}
+
+export function ephemeralEvent<Type extends EphemeralEvent["type"]>(
+  type: Type,
+  data: Extract<EphemeralEvent, { type: Type }>["data"],
+) {
+  ids.next++
+  return { id: `evt_${ids.next}`, created: ids.next, type, data }
+}
+
+export function createSseFixture(options: FixtureOptions = {}) {
+  const encoder = new TextEncoder()
+  const streams = new Set<ReadableStreamDefaultController<Uint8Array>>()
+  const requests: RequestRecord[] = []
+  const messages = new Map<string, SessionMessageInfo>()
+
+  const send = (event: unknown) => {
+    for (const stream of streams) {
+      try {
+        stream.enqueue(encoder.encode(`data: ${JSON.stringify(event)}\n\n`))
+      } catch {
+        streams.delete(stream)
+      }
+    }
+  }
+
+  const server = Bun.serve({
+    port: 0,
+    async fetch(request) {
+      const url = new URL(request.url)
+      const body = request.method === "GET" ? undefined : await request.json().catch(() => undefined)
+      requests.push({ method: request.method, path: url.pathname, ...(body === undefined ? {} : { body }) })
+
+      if (url.pathname === "/api/event") {
+        const state: { stream?: ReadableStreamDefaultController<Uint8Array> } = {}
+        return new Response(
+          new ReadableStream<Uint8Array>({
+            start(stream) {
+              state.stream = stream
+              streams.add(stream)
+              stream.enqueue(
+                encoder.encode(
+                  `data: ${JSON.stringify({ id: "evt_connected", type: "server.connected", data: {} })}\n\n`,
+                ),
+              )
+            },
+            cancel() {
+              if (state.stream) streams.delete(state.stream)
+            },
+          }),
+          { headers: { "content-type": "text/event-stream" } },
+        )
+      }
+
+      const prompt = /^\/api\/session\/([^/]+)\/prompt$/.exec(url.pathname)
+      if (prompt?.[1]) {
+        const id = stringField(body, "id")
+        if (!id) return new Response(null, { status: 400 })
+        await options.onPrompt?.({
+          sessionID: decodeURIComponent(prompt[1]),
+          id,
+          body,
+          signal: request.signal,
+          send,
+        })
+        return Response.json({ data: { text: stringField(body, "text") ?? "" } })
+      }
+
+      const message = /^\/api\/session\/([^/]+)\/message\/([^/]+)$/.exec(url.pathname)
+      if (message?.[1] && message[2]) {
+        const sessionID = decodeURIComponent(message[1])
+        const messageID = decodeURIComponent(message[2])
+        return Response.json({
+          data: messages.get(`${sessionID}/${messageID}`) ?? messages.get(messageID) ?? assistantMessage(messageID),
+        })
+      }
+
+      const permission = /^\/api\/session\/([^/]+)\/permission\/([^/]+)\/reply$/.exec(url.pathname)
+      if (permission?.[1] && permission[2]) {
+        const reply = stringField(body, "reply")
+        if (!reply) return new Response(null, { status: 400 })
+        await options.onPermissionReply?.({
+          sessionID: decodeURIComponent(permission[1]),
+          requestID: decodeURIComponent(permission[2]),
+          reply,
+          body,
+          send,
+        })
+        return new Response(null, { status: 204 })
+      }
+
+      const form = /^\/api\/session\/([^/]+)\/form\/([^/]+)\/cancel$/.exec(url.pathname)
+      if (form?.[1] && form[2]) {
+        await options.onFormCancel?.({
+          sessionID: decodeURIComponent(form[1]),
+          formID: decodeURIComponent(form[2]),
+          send,
+        })
+        return new Response(null, { status: 204 })
+      }
+
+      const interrupt = /^\/api\/session\/([^/]+)\/interrupt$/.exec(url.pathname)
+      if (interrupt?.[1]) {
+        await options.onInterrupt?.({ sessionID: decodeURIComponent(interrupt[1]), send })
+        return new Response(null, { status: 204 })
+      }
+
+      return new Response(null, { status: 404 })
+    },
+  })
+
+  return {
+    client: OpenCode.make({ baseUrl: server.url.toString() }),
+    messages,
+    requests,
+    send,
+    async stop() {
+      for (const stream of streams) {
+        try {
+          stream.close()
+        } catch {}
+      }
+      streams.clear()
+      await server.stop(true)
+    },
+  }
+}
+
+export async function withTimeout<Value>(promise: Promise<Value>, message: string, milliseconds = 2_000) {
+  const timeout = Promise.withResolvers<never>()
+  const timer = setTimeout(() => timeout.reject(new Error(message)), milliseconds)
+  try {
+    return await Promise.race([promise, timeout.promise])
+  } finally {
+    clearTimeout(timer)
+  }
+}
+
+function stringField(value: unknown, key: string) {
+  if (!value || typeof value !== "object") return undefined
+  const field = Reflect.get(value, key)
+  return typeof field === "string" ? field : undefined
+}
+
+function assistantMessage(id: string) {
+  return {
+    id,
+    type: "assistant",
+    agent: "build",
+    model: { providerID: "test", id: "test-model" },
+    content: [],
+    finish: "stop",
+    tokens: { input: 1, output: 1, reasoning: 0, cache: { read: 0, write: 0 } },
+    time: { created: 1, completed: 2 },
+  } satisfies SessionMessageInfo
+}

packages/cli/test/acp/subprocess.ts

@@ -0,0 +1,384 @@
+import type {
+  InitializeResponse,
+  NewSessionResponse,
+  SessionConfigOption,
+  SessionConfigSelectOption,
+} from "@agentclientprotocol/sdk"
+import fs from "node:fs/promises"
+import os from "node:os"
+import path from "node:path"
+
+type JsonRpcRequest = {
+  readonly jsonrpc: "2.0"
+  readonly id: number
+  readonly method: string
+  readonly params?: unknown
+}
+
+export type JsonRpcError = {
+  readonly code: number
+  readonly message?: string
+  readonly data?: unknown
+}
+
+export type JsonRpcResponse<T> = {
+  readonly jsonrpc: "2.0"
+  readonly id: number
+  readonly result?: T
+  readonly error?: JsonRpcError
+}
+
+type JsonRpcNotification<T> = {
+  readonly jsonrpc: "2.0"
+  readonly method: string
+  readonly params: T
+}
+
+type JsonRpcMessage = Record<string, unknown>
+
+type Waiter = {
+  readonly predicate: (message: JsonRpcMessage) => boolean
+  readonly resolve: (message: JsonRpcMessage) => void
+  readonly reject: (error: Error) => void
+  readonly timer: ReturnType<typeof setTimeout>
+}
+
+export type AcpProcess = {
+  readonly request: <T>(method: string, params?: unknown) => Promise<JsonRpcResponse<T>>
+  readonly waitForNotification: <T>(
+    method: string,
+    predicate: (params: T) => boolean,
+    timeoutMs?: number,
+  ) => Promise<JsonRpcNotification<T>>
+  readonly close: () => Promise<number>
+  readonly stderr: () => string
+  readonly [Symbol.asyncDispose]: () => Promise<void>
+}
+
+export const verifierSkill = `---
+name: verifier-skill
+description: Verifier compatibility skill.
+---
+
+# Verifier Skill
+`
+
+export async function createAcpFixture(options: { readonly skill?: string } = {}) {
+  const root = await fs.mkdtemp(path.join(os.tmpdir(), "opencode-cli-acp-"))
+  const home = path.join(root, "workspace")
+  const config = path.join(root, "config")
+  const skills = path.join(root, "skills")
+  await Promise.all([fs.mkdir(home, { recursive: true }), fs.mkdir(config, { recursive: true })])
+  if (options.skill) {
+    await fs.mkdir(path.join(skills, "verifier-skill"), { recursive: true })
+    await Bun.write(path.join(skills, "verifier-skill", "SKILL.md"), options.skill)
+  }
+
+  const requests: unknown[] = []
+  const llm = Bun.serve({
+    hostname: "127.0.0.1",
+    port: 0,
+    async fetch(request) {
+      if (request.method !== "POST" || new URL(request.url).pathname !== "/v1/chat/completions") {
+        return new Response("Not found", { status: 404 })
+      }
+      requests.push(await request.json().catch(() => undefined))
+      return new Response(completion("accepted"), {
+        headers: { "content-type": "text/event-stream" },
+      })
+    },
+  })
+  await Bun.write(
+    path.join(config, "opencode.json"),
+    JSON.stringify(verifierConfig(`http://127.0.0.1:${llm.port}/v1`, options.skill ? skills : undefined)),
+  )
+
+  const processes = new Set<AcpProcess>()
+  return {
+    root,
+    home,
+    llm: { requests },
+    spawn(extraEnv: Record<string, string | undefined> = {}) {
+      const acp = spawnAcp({
+        env: {
+          ...process.env,
+          HOME: root,
+          USERPROFILE: root,
+          OPENCODE_CONFIG: undefined,
+          OPENCODE_CONFIG_CONTENT: undefined,
+          OPENCODE_CONFIG_DIR: config,
+          OPENCODE_DB: path.join(root, "opencode.db"),
+          OPENCODE_DISABLE_AUTOUPDATE: "true",
+          OPENCODE_DISABLE_FILEWATCHER: "true",
+          OPENCODE_DISABLE_MODELS_FETCH: "true",
+          OPENCODE_MODELS_PATH: undefined,
+          OPENCODE_TEST_HOME: root,
+          XDG_CACHE_HOME: path.join(root, "cache"),
+          XDG_CONFIG_HOME: path.join(root, "xdg-config"),
+          XDG_DATA_HOME: path.join(root, "data"),
+          XDG_STATE_HOME: path.join(root, "state"),
+          ...extraEnv,
+        },
+      })
+      processes.add(acp)
+      return acp
+    },
+    async [Symbol.asyncDispose]() {
+      await Promise.all([...processes].map((process) => process[Symbol.asyncDispose]()))
+      await llm.stop(true)
+      await fs.rm(root, { recursive: true, force: true, maxRetries: 5, retryDelay: 100 })
+    },
+  }
+}
+
+export function initialize(acp: AcpProcess) {
+  return acp
+    .request<InitializeResponse>("initialize", {
+      protocolVersion: 1,
+      clientCapabilities: { _meta: { "terminal-auth": true } },
+      clientInfo: { name: "opencode-local-acp", version: "0.1.0" },
+    })
+    .then(expectOk)
+}
+
+export function newSession(acp: AcpProcess, cwd: string) {
+  return acp.request<NewSessionResponse>("session/new", { cwd, mcpServers: [] }).then(expectOk)
+}
+
+export function expectOk<T>(response: JsonRpcResponse<T>) {
+  if (response.error) throw new Error(`ACP request failed: ${JSON.stringify(response.error)}`)
+  if (response.result === undefined) throw new Error("ACP response did not include a result")
+  return response.result
+}
+
+export function selectConfigOption(options: SessionConfigOption[] | null | undefined, id: string) {
+  return options?.find(
+    (option): option is Extract<SessionConfigOption, { type: "select" }> =>
+      option.id === id && option.type === "select",
+  )
+}
+
+export function requireSelectOption(options: SessionConfigOption[] | null | undefined, id: string) {
+  const option = selectConfigOption(options, id)
+  if (!option) throw new Error(`Missing ACP config option: ${id}`)
+  return option
+}
+
+export function flattenSelectOptions(option: Extract<SessionConfigOption, { type: "select" }>) {
+  return option.options.flatMap((item): SessionConfigSelectOption[] => ("value" in item ? [item] : item.options))
+}
+
+export function alternateValue(option: Extract<SessionConfigOption, { type: "select" }>) {
+  const value = flattenSelectOptions(option).find((item) => item.value !== option.currentValue)?.value
+  if (!value) throw new Error(`ACP config option ${option.id} has no alternate value`)
+  return value
+}
+
+function verifierConfig(llmUrl: string, skills?: string) {
+  const model = {
+    capabilities: { tools: true, input: ["text", "image"], output: ["text"] },
+    cost: { input: 0, output: 0 },
+    limit: { context: 100_000, output: 10_000 },
+  }
+  return {
+    autoupdate: false,
+    model: "test/test-model",
+    ...(skills ? { skills: [skills] } : {}),
+    providers: {
+      test: {
+        name: "Test",
+        package: "aisdk:@ai-sdk/openai-compatible",
+        settings: { apiKey: "test-key", baseURL: llmUrl },
+        models: {
+          "test-model": {
+            ...model,
+            name: "Test Model",
+            variants: [{ id: "low" }, { id: "high" }],
+          },
+          "second-model": {
+            ...model,
+            name: "Second Test Model",
+            variants: [{ id: "medium" }, { id: "max" }],
+          },
+        },
+      },
+    },
+  }
+}
+
+function spawnAcp(input: { readonly env: Record<string, string | undefined> }): AcpProcess {
+  const child = Bun.spawn([process.execPath, "run", "src/index.ts", "acp"], {
+    cwd: path.join(import.meta.dir, "../.."),
+    env: input.env,
+    stdin: "pipe",
+    stdout: "pipe",
+    stderr: "pipe",
+  })
+  const encoder = new TextEncoder()
+  const decoder = new TextDecoder()
+  const errorDecoder = new TextDecoder()
+  const messages: JsonRpcMessage[] = []
+  const waiters: Waiter[] = []
+  let nextID = 1
+  let failure: Error | undefined
+  let stderr = ""
+  let inputClosed = false
+  let disposed = false
+
+  const fail = (error: Error) => {
+    if (failure) return
+    failure = error
+    waiters.splice(0).forEach((waiter) => {
+      clearTimeout(waiter.timer)
+      waiter.reject(error)
+    })
+  }
+
+  const dispatch = (message: JsonRpcMessage) => {
+    const index = waiters.findIndex((waiter) => waiter.predicate(message))
+    if (index === -1) {
+      messages.push(message)
+      return
+    }
+    const waiter = waiters.splice(index, 1)[0]
+    clearTimeout(waiter.timer)
+    waiter.resolve(message)
+  }
+
+  const output = (async () => {
+    const reader = child.stdout.getReader()
+    let buffered = ""
+    while (true) {
+      const chunk = await reader.read()
+      if (chunk.done) break
+      buffered += decoder.decode(chunk.value, { stream: true })
+      while (true) {
+        const newline = buffered.indexOf("\n")
+        if (newline === -1) break
+        const line = buffered.slice(0, newline).trim()
+        buffered = buffered.slice(newline + 1)
+        if (line) dispatch(parseMessage(line))
+      }
+    }
+    buffered += decoder.decode()
+    if (buffered.trim()) dispatch(parseMessage(buffered.trim()))
+    fail(new Error(`ACP exited before another response${stderr ? `: ${stderr}` : ""}`))
+  })().catch((error) => fail(asError(error)))
+
+  const errors = (async () => {
+    const reader = child.stderr.getReader()
+    while (true) {
+      const chunk = await reader.read()
+      if (chunk.done) break
+      stderr += errorDecoder.decode(chunk.value, { stream: true })
+    }
+    stderr += errorDecoder.decode()
+  })()
+
+  const take = (predicate: (message: JsonRpcMessage) => boolean, timeoutMs: number, description: string) => {
+    const index = messages.findIndex(predicate)
+    if (index !== -1) return Promise.resolve(messages.splice(index, 1)[0])
+    if (failure) return Promise.reject(failure)
+    return new Promise<JsonRpcMessage>((resolve, reject) => {
+      const waiter: Waiter = {
+        predicate,
+        resolve,
+        reject,
+        timer: setTimeout(() => {
+          const index = waiters.indexOf(waiter)
+          if (index !== -1) waiters.splice(index, 1)
+          reject(new Error(`Timed out waiting for ${description}${stderr ? `: ${stderr}` : ""}`))
+        }, timeoutMs),
+      }
+      waiters.push(waiter)
+    })
+  }
+
+  return {
+    async request<T>(method: string, params?: unknown) {
+      if (inputClosed) throw new Error("ACP stdin is closed")
+      const id = nextID++
+      const request: JsonRpcRequest =
+        params === undefined ? { jsonrpc: "2.0", id, method } : { jsonrpc: "2.0", id, method, params }
+      await child.stdin.write(encoder.encode(`${JSON.stringify(request)}\n`))
+      await child.stdin.flush()
+      const response = await take((message) => isResponse(message) && message.id === id, 20_000, `${method} response`)
+      if (!isResponse<T>(response)) throw new Error(`Invalid ACP response: ${JSON.stringify(response)}`)
+      return response
+    },
+    async waitForNotification<T>(method: string, predicate: (params: T) => boolean, timeoutMs = 20_000) {
+      const notification = await take(
+        (message) => isNotification<T>(message) && message.method === method && predicate(message.params),
+        timeoutMs,
+        `${method} notification`,
+      )
+      if (!isNotification<T>(notification)) {
+        throw new Error(`Invalid ACP notification: ${JSON.stringify(notification)}`)
+      }
+      return notification
+    },
+    async close() {
+      if (!inputClosed) {
+        inputClosed = true
+        await child.stdin.end()
+      }
+      const exitCode = await withTimeout(child.exited, 5_000, "ACP did not exit after stdin EOF")
+      await Promise.all([output, errors])
+      if (exitCode !== 0) throw new Error(`ACP exited with ${exitCode}: ${stderr}`)
+      return exitCode
+    },
+    stderr: () => stderr,
+    async [Symbol.asyncDispose]() {
+      if (disposed) return
+      disposed = true
+      if (child.exitCode === null) child.kill("SIGKILL")
+      await child.exited
+      await Promise.all([output, errors])
+    },
+  }
+}
+
+function parseMessage(line: string): JsonRpcMessage {
+  const message: unknown = JSON.parse(line)
+  if (!isJsonRpcMessage(message)) throw new Error(`Invalid ACP message: ${line}`)
+  return message
+}
+
+function isJsonRpcMessage(message: unknown): message is JsonRpcMessage {
+  return !!message && typeof message === "object" && !Array.isArray(message)
+}
+
+function isResponse<T>(message: JsonRpcMessage): message is JsonRpcMessage & JsonRpcResponse<T> {
+  return message.jsonrpc === "2.0" && typeof message.id === "number" && !("method" in message)
+}
+
+function isNotification<T>(message: JsonRpcMessage): message is JsonRpcMessage & JsonRpcNotification<T> {
+  return message.jsonrpc === "2.0" && typeof message.method === "string" && !("id" in message)
+}
+
+function asError(error: unknown) {
+  return error instanceof Error ? error : new Error(String(error))
+}
+
+function withTimeout<T>(promise: Promise<T>, timeoutMs: number, message: string) {
+  let timer: ReturnType<typeof setTimeout> | undefined
+  return Promise.race([
+    promise,
+    new Promise<T>((_, reject) => {
+      timer = setTimeout(() => reject(new Error(message)), timeoutMs)
+    }),
+  ]).finally(() => clearTimeout(timer))
+}
+
+function completion(text: string) {
+  const chunks = [
+    { choices: [{ delta: { role: "assistant" }, finish_reason: null }], usage: null },
+    { choices: [{ delta: { content: text }, finish_reason: null }], usage: null },
+    { choices: [{ delta: {}, finish_reason: "stop" }], usage: null },
+    {
+      choices: [],
+      usage: { prompt_tokens: 10, completion_tokens: 1, total_tokens: 11 },
+    },
+  ]
+  return `${chunks.map((chunk) => `data: ${JSON.stringify(chunk)}\n\n`).join("")}data: [DONE]\n\n`
+}

packages/cli/test/acp/tool.test.ts

@@ -0,0 +1,292 @@
+import { resolve } from "node:path"
+import { describe, expect, test } from "bun:test"
+import {
+  completedToolUpdate,
+  errorToolUpdate,
+  pendingToolCall,
+  runningToolUpdate,
+  toLocations,
+  toToolKind,
+} from "../../src/acp/tool"
+
+describe("acp tools", () => {
+  test("maps OpenCode tool ids to ACP tool kinds", () => {
+    expect(toToolKind("bash")).toBe("execute")
+    expect(toToolKind("shell")).toBe("execute")
+    expect(toToolKind("webfetch")).toBe("fetch")
+    expect(toToolKind("edit")).toBe("edit")
+    expect(toToolKind("apply_patch")).toBe("edit")
+    expect(toToolKind("patch")).toBe("edit")
+    expect(toToolKind("write")).toBe("edit")
+    expect(toToolKind("grep")).toBe("search")
+    expect(toToolKind("glob")).toBe("search")
+    expect(toToolKind("context7_resolve_library_id")).toBe("search")
+    expect(toToolKind("context7_get_library_docs")).toBe("search")
+    expect(toToolKind("read")).toBe("read")
+    expect(toToolKind("task")).toBe("think")
+    expect(toToolKind("custom_tool")).toBe("other")
+  })
+
+  test("extracts file locations from tool input", () => {
+    expect(toLocations("read", { filePath: "/tmp/a.ts" })).toEqual([{ path: "/tmp/a.ts" }])
+    expect(toLocations("edit", { filePath: "/tmp/b.ts" })).toEqual([{ path: "/tmp/b.ts" }])
+    expect(toLocations("write", { filePath: "/tmp/c.ts" })).toEqual([{ path: "/tmp/c.ts" }])
+    expect(toLocations("grep", { path: "/repo/src" })).toEqual([{ path: "/repo/src" }])
+    expect(toLocations("glob", { path: "/repo/test" })).toEqual([{ path: "/repo/test" }])
+    expect(toLocations("context7_get_library_docs", { path: "/docs" })).toEqual([{ path: "/docs" }])
+    expect(toLocations("external_directory", { directories: ["/tmp/outside"], patterns: ["/tmp/outside/*"] })).toEqual([
+      { path: "/tmp/outside" },
+    ])
+    expect(toLocations("bash", { cmd: "pwd" }, "/workspace")).toEqual([{ path: "/workspace" }])
+    expect(toLocations("bash", { command: "pwd", workdir: "subdir" }, "/workspace")).toEqual([
+      { path: resolve("/workspace", "subdir") },
+    ])
+    expect(toLocations("bash", { command: "pwd", workdir: "/abs/dir" }, "/workspace")).toEqual([{ path: "/abs/dir" }])
+    expect(toLocations("bash", { command: "printf hello" })).toEqual([])
+    expect(toLocations("read", { path: "/tmp/missing-file-path.ts" })).toEqual([])
+  })
+
+  test("builds completed content with text and image attachments", () => {
+    const image = Buffer.from("image-data").toString("base64")
+
+    expect(
+      completedToolUpdate({
+        toolCallId: "tool-1",
+        toolName: "edit",
+        input: {
+          filePath: "/tmp/file.ts",
+          oldString: "before",
+          newString: "after",
+        },
+        content: [
+          { type: "text", text: "edited /tmp/file.ts" },
+          { type: "file", mime: "image/png", name: "image.png", uri: `data:image/png;base64,${image}` },
+          { type: "file", mime: "text/plain", name: "note.txt", uri: "data:text/plain;base64,bm90ZQ==" },
+        ],
+        structured: {},
+      }).content,
+    ).toEqual([
+      {
+        type: "content",
+        content: { type: "text", text: "edited /tmp/file.ts" },
+      },
+      {
+        type: "diff",
+        path: "/tmp/file.ts",
+        oldText: "before",
+        newText: "after",
+      },
+      {
+        type: "content",
+        content: { type: "image", mimeType: "image/png", data: image },
+      },
+    ])
+  })
+
+  test("omits edit diffs when normalized content does not contain one", () => {
+    expect(
+      completedToolUpdate({
+        toolCallId: "tool-1",
+        toolName: "write",
+        input: {
+          filePath: "/tmp/file.ts",
+          content: "created",
+        },
+        content: [{ type: "text", text: "wrote /tmp/file.ts" }],
+        structured: {},
+      }).content,
+    ).toEqual([
+      {
+        type: "content",
+        content: { type: "text", text: "wrote /tmp/file.ts" },
+      },
+    ])
+  })
+
+  test("uses clean structured read content instead of model-facing formatting", () => {
+    expect(
+      completedToolUpdate({
+        toolCallId: "tool-read",
+        toolName: "read",
+        input: { path: "/tmp/file.ts" },
+        content: [{ type: "text", text: "<content>1: first\n2: second</content>" }],
+        structured: {
+          type: "text-page",
+          content: "first\nsecond",
+          mime: "text/plain",
+          offset: 1,
+          truncated: false,
+        },
+      }).content,
+    ).toEqual([{ type: "content", content: { type: "text", text: "first\nsecond" } }])
+
+    expect(
+      completedToolUpdate({
+        toolCallId: "tool-list",
+        toolName: "read",
+        input: { path: "/tmp" },
+        content: [],
+        structured: {
+          entries: [
+            { path: "a.ts", type: "file" },
+            { path: "src", type: "directory" },
+          ],
+        },
+      }).content,
+    ).toEqual([{ type: "content", content: { type: "text", text: "a.ts\nsrc" } }])
+  })
+
+  test("sends completed tool calls as partial updates", () => {
+    expect(
+      pendingToolCall({
+        toolCallId: "tool-1",
+        toolName: "edit",
+        state: {
+          input: {
+            filePath: "/tmp/file.ts",
+            oldString: "before",
+            newString: "after",
+          },
+        },
+      }),
+    ).toMatchObject({
+      toolCallId: "tool-1",
+      status: "pending",
+      kind: "edit",
+      locations: [{ path: "/tmp/file.ts" }],
+      rawInput: {
+        filePath: "/tmp/file.ts",
+        oldString: "before",
+        newString: "after",
+      },
+    })
+
+    expect(
+      completedToolUpdate({
+        toolCallId: "tool-1",
+        toolName: "edit",
+        input: {
+          filePath: "/tmp/file.ts",
+          oldString: "before",
+          newString: "after",
+        },
+        content: [{ type: "text", text: "Edit applied successfully." }],
+        structured: { output: "Edit applied successfully." },
+      }),
+    ).toEqual({
+      toolCallId: "tool-1",
+      status: "completed",
+      content: [
+        {
+          type: "content",
+          content: { type: "text", text: "Edit applied successfully." },
+        },
+        {
+          type: "diff",
+          path: "/tmp/file.ts",
+          oldText: "before",
+          newText: "after",
+        },
+      ],
+      rawOutput: {
+        structured: { output: "Edit applied successfully." },
+      },
+    })
+  })
+
+  test("builds running tool updates with normalized content", () => {
+    expect(
+      runningToolUpdate({
+        toolCallId: "call",
+        toolName: "read",
+        state: { input: { filePath: "/tmp/a" } },
+        content: [{ type: "text", text: "done" }],
+      }),
+    ).toMatchObject({
+      toolCallId: "call",
+      status: "in_progress",
+      content: [{ type: "content", content: { type: "text", text: "done" } }],
+    })
+  })
+
+  test("builds completed raw output with structured data and optional result", () => {
+    const attachments = [
+      {
+        type: "file",
+        mime: "image/jpeg",
+        name: "photo.jpg",
+        uri: "data:image/jpeg;base64,AAAA",
+      },
+    ]
+
+    expect(
+      completedToolUpdate({
+        toolCallId: "call",
+        toolName: "read",
+        input: {},
+        content: [],
+        structured: { output: "done", metadata: { exit: 0 }, attachments },
+        result: "done",
+      }).rawOutput,
+    ).toEqual({
+      structured: { output: "done", metadata: { exit: 0 }, attachments },
+      result: "done",
+    })
+
+    expect(
+      completedToolUpdate({
+        toolCallId: "call",
+        toolName: "read",
+        input: {},
+        content: [],
+        structured: { output: "done" },
+      }).rawOutput,
+    ).toEqual({ structured: { output: "done" } })
+  })
+
+  test("extracts image attachments only from data URLs", () => {
+    expect(
+      completedToolUpdate({
+        toolCallId: "call",
+        toolName: "read",
+        input: {},
+        content: [
+          { type: "file", mime: "image/webp", uri: "data:image/webp;charset=utf-8;base64,AAAA" },
+          { type: "file", mime: "image/png", uri: "https://example.com/image.png" },
+          { type: "file", mime: "text/plain", uri: "data:text/plain;base64,BBBB" },
+        ],
+        structured: {},
+      }).content,
+    ).toEqual([
+      {
+        type: "content",
+        content: { type: "image", mimeType: "image/webp", data: "AAAA" },
+      },
+    ])
+  })
+
+  test("builds failed tool updates", () => {
+    expect(
+      errorToolUpdate({
+        toolCallId: "call",
+        toolName: "read",
+        input: { filePath: "/tmp/a" },
+        content: [{ type: "text", text: "partial output" }],
+        structured: { path: "/tmp/a" },
+        error: "failed",
+      }),
+    ).toEqual({
+      toolCallId: "call",
+      status: "failed",
+      kind: "read",
+      title: "read",
+      locations: [{ path: "/tmp/a" }],
+      rawInput: { filePath: "/tmp/a" },
+      content: [
+        { type: "content", content: { type: "text", text: "partial output" } },
+        { type: "content", content: { type: "text", text: "failed" } },
+      ],
+      rawOutput: { structured: { path: "/tmp/a" }, error: "failed" },
+    })
+  })
+})

packages/core/package.json

@@ -41,11 +41,6 @@
       "node": "./src/image/photon-wasm.node.ts",
       "default": "./src/image/photon-wasm.bun.ts"
     },
-    "#runtime-import": {
-      "bun": "@opencode-ai/util/runtime/import.bun",
-      "node": "@opencode-ai/util/runtime/import.node",
-      "default": "@opencode-ai/util/runtime/import.bun"
-    },
     "#process-lock-ffi": {
       "bun": "./src/util/process-lock-ffi.bun.ts",
       "node": "./src/util/process-lock-ffi.node.ts",

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

@@ -2,7 +2,7 @@ import { Effect } from "effect"
 import { pathToFileURL } from "url"
 import { define } from "@opencode-ai/plugin/v2/effect/plugin"
 import { Npm } from "@opencode-ai/util/npm"
-import { importModule } from "#runtime-import"
+import { importModule } from "@opencode-ai/util/runtime-import"
 
 export const DynamicProviderPlugin = define({
   id: "opencode.provider.dynamic",

packages/core/src/plugin/provider/sap-ai-core.ts

@@ -3,7 +3,7 @@ import { pathToFileURL } from "url"
 import { define } from "@opencode-ai/plugin/v2/effect/plugin"
 import { Npm } from "@opencode-ai/util/npm"
 import { ProviderV2 } from "../../provider"
-import { importModule } from "#runtime-import"
+import { importModule } from "@opencode-ai/util/runtime-import"
 
 export const SapAICorePlugin = define({
   id: "opencode.provider.sap-ai-core",

packages/core/src/plugin/supervisor.ts

@@ -39,7 +39,7 @@ import { WellKnown } from "../wellknown"
 import { PluginInternal } from "./internal"
 import { PluginRuntime } from "./runtime"
 import { SdkPlugins } from "./sdk"
-import { importModule } from "#runtime-import"
+import { importModule } from "@opencode-ai/util/runtime-import"
 
 const PluginModule = Schema.Struct({
   default: Schema.Union([

packages/core/src/provider.ts

@@ -5,7 +5,7 @@ import { Provider } from "@opencode-ai/schema/provider"
 import type { ProviderPackageDefinition } from "@opencode-ai/ai"
 import { Npm } from "@opencode-ai/util/npm"
 import type { DeepMutable } from "./schema"
-import { importModule, resolveModule } from "#runtime-import"
+import { importModule, resolveModule } from "@opencode-ai/util/runtime-import"
 
 export const ID = Provider.ID
 export type ID = typeof ID.Type

packages/core/src/tool/patch.ts

@@ -8,7 +8,7 @@ import { Effect, Schema } from "effect"
 import path from "path"
 import { FSUtil } from "@opencode-ai/util/fs-util"
 import { Location } from "../location"
-import { Patch } from "../patch"
+import { Patch } from "@opencode-ai/util/patch"
 import { PermissionV2 } from "../permission"
 import { Tool } from "./tool"
 import DESCRIPTION from "./patch.txt"
@@ -186,8 +186,7 @@ export const Plugin = {
                       const before = original.replace(/^\uFEFF/, "")
                       const update = yield* Effect.try({
                         try: () => Patch.derive(hunk.path, hunk.chunks, original),
-                        catch: (error) =>
-                          new ToolFailure({ message: `patch verification failed: ${String(error)}` }),
+                        catch: (error) => new ToolFailure({ message: `patch verification failed: ${String(error)}` }),
                       })
                       const moveTarget = hunk.movePath ? resolveTarget(location, hunk.movePath) : undefined
                       if (moveTarget?.externalDirectory) {

packages/core/test/patch.test.ts

@@ -1,5 +1,5 @@
 import { describe, expect, test } from "bun:test"
-import { Patch } from "@opencode-ai/core/patch"
+import { Patch } from "@opencode-ai/util/patch"
 import { Result } from "effect"
 
 const parse = (input: string) => Result.getOrThrow(Patch.parse(input))
@@ -24,9 +24,7 @@ describe("Patch", () => {
 
   test("parses a file move", () => {
     expect(
-      parse(
-        "*** Begin Patch\n*** Update File: old.txt\n*** Move to: new.txt\n@@\n-old\n+new\n*** End Patch",
-      ),
+      parse("*** Begin Patch\n*** Update File: old.txt\n*** Move to: new.txt\n@@\n-old\n+new\n*** End Patch"),
     ).toEqual([
       {
         type: "update",
@@ -38,9 +36,7 @@ describe("Patch", () => {
   })
 
   test("identifies the missing patch boundary", () => {
-    expect(() => parse("This is not a valid patch")).toThrow(
-      "The first line of the patch must be '*** Begin Patch'",
-    )
+    expect(() => parse("This is not a valid patch")).toThrow("The first line of the patch must be '*** Begin Patch'")
     expect(() => parse("*** Begin Patch\n*** Add File: add.txt\n+added")).toThrow(
       "The last line of the patch must be '*** End Patch'",
     )
@@ -148,12 +144,8 @@ describe("Patch", () => {
   })
 
   test("updates empty files and adds a trailing newline", () => {
-    expect(Patch.derive("empty.txt", [{ oldLines: [], newLines: ["First line"] }], "").content).toBe(
-      "First line\n",
-    )
-    expect(Patch.derive("no-newline.txt", [{ oldLines: ["old"], newLines: ["new"] }], "old").content).toBe(
-      "new\n",
-    )
+    expect(Patch.derive("empty.txt", [{ oldLines: [], newLines: ["First line"] }], "").content).toBe("First line\n")
+    expect(Patch.derive("no-newline.txt", [{ oldLines: ["old"], newLines: ["new"] }], "old").content).toBe("new\n")
   })
 
   test("disambiguates updates with change context", () => {
@@ -167,14 +159,12 @@ describe("Patch", () => {
   })
 
   test("matches leading, trailing, and Unicode punctuation differences", () => {
-    expect(Patch.derive("leading.txt", [{ oldLines: ["line"], newLines: ["next"] }], "  line\n").content).toBe(
-      "next\n",
-    )
+    expect(Patch.derive("leading.txt", [{ oldLines: ["line"], newLines: ["next"] }], "  line\n").content).toBe("next\n")
     expect(Patch.derive("trailing.txt", [{ oldLines: ["line"], newLines: ["next"] }], "line  \n").content).toBe(
       "next\n",
     )
     expect(
-      Patch.derive('unicode.txt', [{ oldLines: ['He said "hello"'], newLines: ['He said "hi"'] }], 'He said “hello”\n')
+      Patch.derive("unicode.txt", [{ oldLines: ['He said "hello"'], newLines: ['He said "hi"'] }], "He said “hello”\n")
         .content,
     ).toBe('He said "hi"\n')
   })

packages/util/src/patch.ts

@@ -100,9 +100,7 @@ export function parse(patchText: string): Result.Result<ReadonlyArray<Hunk>, Par
   if (hunks.length === 0) {
     const invalid = lines.findIndex((line, index) => index > begin && index < end && line.trim() !== "")
     if (invalid !== -1) {
-      return Result.fail(
-        new InvalidHunkError({ line: lines[invalid]!.trim(), lineNumber: invalid + 1 }),
-      )
+      return Result.fail(new InvalidHunkError({ line: lines[invalid]!.trim(), lineNumber: invalid + 1 }))
     }
   }
   return Result.succeed(hunks)

packages/util/src/runtime-import.ts

@@ -0,0 +1 @@
+export { importModule, resolveModule } from "#runtime-import"