test(core): simplify command layer wiring

.github/workflows/test.yml

@@ -65,7 +65,7 @@ jobs:
 
       - name: Run unit tests
         timeout-minutes: 20
-        run: bun turbo test --output-logs=errors-only --log-order=grouped --log-prefix=none
+        run: bun turbo test --output-logs=errors-only --log-order=grouped --log-prefix=task
         env:
           OPENCODE_EXPERIMENTAL_DISABLE_FILEWATCHER: ${{ runner.os == 'Windows' && 'true' || 'false' }}
 
@@ -99,8 +99,7 @@ jobs:
       - name: Setup Node
         uses: actions/setup-node@49933ea5288caeca8642d1e84afbd3f7d6820020 # v4.4.0
         with:
-          # Playwright 1.59 hangs while extracting Chromium with Node 24.16.
-          node-version: "24.15"
+          node-version: "24"
 
       - name: Setup Bun
         uses: ./.github/actions/setup-bun

CONTEXT.md

@@ -24,7 +24,7 @@ A durable chronological instruction that tells the model the newly effective sta
 _Avoid_: System update, system notification, raw text diff
 
 **Context Epoch**:
-The span during which one initially rendered **System Context** remains the immutable provider-cache baseline, ending at completed compaction, Session movement, or an incompatible context transition that requires a fresh baseline.
+The span during which one effective agent's initially rendered **System Context** remains immutable, ending at compaction or another baseline-replacing transition.
 
 **Baseline System Context**:
 The full **System Context** rendered at the start of a **Context Epoch**.
@@ -75,28 +75,31 @@ The host-supplied environment overlay applied by the server when creating a PTY,
 - Each **Context Source** loader returns one coherent typed value. `SystemContext.make(...)` hides that value type so differently typed sources compose uniformly. Its codec compares and stores that value; its pure renderers produce model-visible baseline, update, and removal text only when needed.
 - `SystemContext.initialize(...)` observes a composed **System Context** once and produces a fresh **Baseline System Context** with its **Context Snapshot**.
 - `SystemContext.reconcile(...)` observes a composed **System Context** once and returns exactly one next action: unchanged, updated, replacement ready, or replacement blocked.
-- `SystemContext.replace(...)` renders a fresh generation after completed compaction or another baseline-replacing transition; it reports replacement blocked while previously admitted context is unavailable.
+- `SystemContext.replace(...)` represents an explicit baseline-replacing transition such as compaction or model/provider switch; it either produces a fresh generation or reports that replacement is blocked by unavailable admitted context.
+- Context Epoch preparation retries until stable after optimistic revision mismatches so concurrent replacement requests cannot terminate an otherwise valid safe-boundary run.
 - **Unavailable Context** uses stale-while-revalidate semantics and is distinct from a successfully loaded absence, which may emit removal text.
 - Ordinary **Context Source** loaders return values directly; loaders that intentionally use stale-while-revalidate may explicitly return **Unavailable Context**.
 - Nested project instruction discovery after successful reads remains a follow-up; when implemented, discovered instructions must be admitted durably at the next **Safe Provider-Turn Boundary**.
 - Location-scoped services naturally re-resolve effective context when a moved session next runs in its destination location.
 - Moving a Session clears its active **Context Epoch**, so the destination must initialize a complete baseline before another prompt can promote.
+- Context Epoch initialization is fenced against the authoritative Session Location, so an old-Location runner cannot recreate source context after a concurrent move.
 - Instruction discovery, source identity, persistence, and file loading belong to the instruction service; the **System Context** abstraction only composes effectful producers and renders loaded values.
 - The first instruction-service slice observes global and upward project `AGENTS.md` files as one ordered aggregate **Context Source** at each **Safe Provider-Turn Boundary**.
 - Built-in and instruction context producers register through the **System Context Registry** with stable contribution keys. Plugin-defined context registration and hot-reload lifecycle remain a follow-up built on the same scoped registry seam.
 - Selected-agent available-skill guidance is a **Context Source** composed with Location-wide registry sources immediately before Context Epoch admission. It lists only names and descriptions permitted for that agent; skill bodies and locations are exposed only through the permission-checked `skill` tool.
-- The selected agent and model are sampled when a provider turn starts. Changes admitted after that boundary apply to the next provider turn and do not restart the current turn.
-- Selected-agent available-skill guidance remains a **Context Source**. An agent switch that changes that guidance produces a **Mid-Conversation System Message** while preserving the current baseline.
+- Switching the selected agent requests **Context Epoch** replacement. A switch admitted after the current **Safe Provider-Turn Boundary** applies to the next provider turn while leaving the already-prepared baseline durable. Epoch creation is fenced against the authoritative effective agent, and retries re-observe the current agent.
+- A cross-agent replacement must complete before another provider turn; unavailable admitted context blocks that replacement instead of exposing the previous agent's privileged baseline.
 - Local tool authorization and pending permission requests retain the effective agent of the provider turn that issued the call; a later agent switch cannot change that call's policy.
 - Context source changes never wake idle sessions; the next naturally scheduled **Safe Provider-Turn Boundary** loads and compares current values lazily.
 - Once admitted, a **Mid-Conversation System Message** remains durable even if the following provider attempt fails and is replayed unchanged on retry.
 - **Mid-Conversation System Messages** remain durable Session-message history; normal user-facing transcript surfaces may hide them.
 - The date **Context Source** initially preserves host-local calendar-date behavior; a configured user timezone may replace that default later.
 - A **Context Epoch** begins with one immutable **Baseline System Context**.
+- A **Context Epoch** durably records the effective agent that owns its **Baseline System Context**.
 - A **Baseline System Context** is stored durably and reused verbatim across process restarts within its **Context Epoch**.
 - A **Baseline System Context** durably preserves the exact joined text used for the active provider-cache prefix.
-- Completed compaction starts a new **Context Epoch** on the next provider attempt, folding the current complete **System Context** into a fresh baseline and removing earlier **Mid-Conversation System Messages** from active model history.
-- A model/provider switch preserves the current **Context Epoch** and chronological conversation history; the new selection applies to the next provider turn.
+- Compaction or a model/provider switch starts a new **Context Epoch** because the baseline can be replaced without preserving the prior provider cache.
+- A model/provider switch always starts a new **Context Epoch** while preserving chronological conversation history.
 - **Model Request Options** remain provider-semantic through Catalog resolution. The Session runner maps them into the LLM package's provider-option namespace; the selected protocol adapter alone owns provider wire encoding.
 - **Generation Controls**, protocol-semantic **Model Request Options**, and compatibility request body fields are separate Catalog domains. A shared ingestion adapter partitions legacy and models.dev AI-SDK-shaped options before routing.
 - The **PTY Environment** is a server concern rather than a Core PTY concern. PTY creation merges caller values, then the host overlay, then Core-forced terminal invariants such as `TERM` and `OPENCODE_TERMINAL`.

bun.lock

@@ -276,7 +276,6 @@
         "@opencode-ai/effect-drizzle-sqlite": "workspace:*",
         "@opencode-ai/effect-sqlite-node": "workspace:*",
         "@opencode-ai/llm": "workspace:*",
-        "@opencode-ai/plugin": "workspace:*",
         "@openrouter/ai-sdk-provider": "2.9.0",
         "@opentelemetry/api": "1.9.0",
         "@opentelemetry/context-async-hooks": "2.6.1",
@@ -626,7 +625,6 @@
       "name": "@opencode-ai/plugin",
       "version": "1.17.9",
       "dependencies": {
-        "@ai-sdk/provider": "3.0.8",
         "@opencode-ai/sdk": "workspace:*",
         "effect": "catalog:",
         "zod": "catalog:",

nix/hashes.json

@@ -1,8 +1,8 @@
 {
   "nodeModules": {
-    "x86_64-linux": "sha256-oWSGu+SP66Aquy/0Vaq7Bgp8404ZdOWbQX+O7h3jxHU=",
-    "aarch64-linux": "sha256-UsS0+c+GwtIukmWwQeFbY/3Oaz3t4Q7C6cFMGkmlyAY=",
-    "aarch64-darwin": "sha256-CArz92ewPmXO+ORFCBkCH8LzMpU/DjyaO4ic7QL0UpI=",
-    "x86_64-darwin": "sha256-rhnz9gmG6L06wIzfMhTaXDDEf6IbMD32CavqwXoqcUs="
+    "x86_64-linux": "sha256-g0tDvRf7MErZ1PEeUazEYi492ZHiRT8kYv3bPdkss/I=",
+    "aarch64-linux": "sha256-6sKgf3ftbIqlPxlFkoPzoWPsJp3IwXD+H3Y6g874xmk=",
+    "aarch64-darwin": "sha256-Se/Nls/KlkuK2ysDQ9DeAzSaX3NsL2iDdf/dsv2GIXc=",
+    "x86_64-darwin": "sha256-V9MCkqnvQ1nkD2PaaTfNFKkBZGymj6KxrSAK6+DTF8Y="
   }
 }

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

@@ -27,11 +27,9 @@ export default Runtime.handler(
 
 function listen(hostname: string, port: Option.Option<number>, password: string) {
   if (Option.isSome(port)) return bind(hostname, port.value, password)
-  const next = (port: number): ReturnType<typeof bind> =>
-    bind(hostname, port, password).pipe(
-      Effect.catch((error) => (port === 65_535 ? Effect.fail(error) : next(port + 1))),
-    )
-  return next(4096)
+  // Preserve the familiar default when available, but let the OS choose a free
+  // port when another local server already owns 4096.
+  return bind(hostname, 4096, password).pipe(Effect.catch(() => bind(hostname, 0, password)))
 }
 
 function bind(hostname: string, port: number, password: string) {

packages/core/bunfig.toml

@@ -1,2 +0,0 @@
-[test]
-preload = ["./test/preload.ts"]

packages/core/package.json

@@ -91,7 +91,6 @@
     "@opencode-ai/effect-drizzle-sqlite": "workspace:*",
     "@opencode-ai/effect-sqlite-node": "workspace:*",
     "@opencode-ai/llm": "workspace:*",
-    "@opencode-ai/plugin": "workspace:*",
     "@opentelemetry/api": "1.9.0",
     "@opentelemetry/context-async-hooks": "2.6.1",
     "@opentelemetry/exporter-trace-otlp-http": "0.214.0",

packages/core/schema.json

@@ -1,8 +1,8 @@
 {
   "version": "7",
   "dialect": "sqlite",
-  "id": "f14a9b18-8207-487e-a3d3-227e629ba9ad",
-  "prevIds": ["169a0f0f-d58f-479f-b024-fa1c7b9a09db"],
+  "id": "169a0f0f-d58f-479f-b024-fa1c7b9a09db",
+  "prevIds": ["abd2f920-b822-49af-b8a7-2e48367d424f"],
   "ddl": [
     {
       "name": "workspace",
@@ -900,6 +900,16 @@
       "entityType": "columns",
       "table": "session_context_epoch"
     },
+    {
+      "type": "text",
+      "notNull": true,
+      "autoincrement": false,
+      "default": "'build'",
+      "generated": null,
+      "name": "agent",
+      "entityType": "columns",
+      "table": "session_context_epoch"
+    },
     {
       "type": "text",
       "notNull": true,
@@ -920,6 +930,26 @@
       "entityType": "columns",
       "table": "session_context_epoch"
     },
+    {
+      "type": "integer",
+      "notNull": false,
+      "autoincrement": false,
+      "default": null,
+      "generated": null,
+      "name": "replacement_seq",
+      "entityType": "columns",
+      "table": "session_context_epoch"
+    },
+    {
+      "type": "integer",
+      "notNull": true,
+      "autoincrement": false,
+      "default": "0",
+      "generated": null,
+      "name": "revision",
+      "entityType": "columns",
+      "table": "session_context_epoch"
+    },
     {
       "type": "text",
       "notNull": false,

packages/core/script/migration.ts

@@ -45,17 +45,15 @@ async function generate() {
       if (await Bun.file(target).exists()) throw new Error(`Database migration already exists: ${name}`)
       await Bun.write(
         target,
-        await formatTypescript(
-          renderMigration(name, await Bun.file(path.join(incremental, name, "migration.sql")).text()),
-        ),
+        renderMigration(name, await Bun.file(path.join(incremental, name, "migration.sql")).text()),
       )
       await fs.copyFile(path.join(incremental, name, "snapshot.json"), snapshot)
     }
 
     await fs.mkdir(full)
     await drizzle(temporary, full, "schema")
-    await Bun.write(schema, await formatTypescript(renderSchema(await generatedSql(full))))
-    await Bun.write(registry, await formatTypescript(renderRegistry(await typescriptMigrations())))
+    await Bun.write(schema, renderSchema(await generatedSql(full)))
+    await Bun.write(registry, renderRegistry(await typescriptMigrations()))
   } finally {
     await fs.rm(temporary, { recursive: true, force: true })
   }
@@ -78,12 +76,12 @@ async function check() {
 
     await fs.mkdir(full)
     await drizzle(temporary, full, "schema")
-    if ((await Bun.file(schema).text()) !== (await formatTypescript(renderSchema(await generatedSql(full))))) {
+    if ((await Bun.file(schema).text()) !== renderSchema(await generatedSql(full))) {
       throw new Error("Current database schema is stale. Run `bun script/migration.ts` from packages/core.")
     }
 
     const migrations = await typescriptMigrations()
-    if ((await Bun.file(registry).text()) !== (await formatTypescript(renderRegistry(migrations)))) {
+    if ((await Bun.file(registry).text()) !== renderRegistry(migrations)) {
       throw new Error("Database migration registry is stale. Run `bun script/migration.ts` from packages/core.")
     }
   } finally {
@@ -172,18 +170,6 @@ function escapeTemplate(line: string) {
   return line.replaceAll("\\", "\\\\").replaceAll("`", "\\`").replaceAll("${", "\\${")
 }
 
-async function formatTypescript(input: string) {
-  const prettier = await import("prettier")
-  const typescript = await import("prettier/plugins/typescript")
-  const estree = await import("prettier/plugins/estree")
-  return prettier.format(input, {
-    parser: "typescript",
-    plugins: [typescript.default, estree.default],
-    semi: false,
-    printWidth: 120,
-  })
-}
-
 function renderRegistry(names: string[]) {
   return `import type { DatabaseMigration } from "./migration"
 

packages/core/src/agent.ts

@@ -1,6 +1,7 @@
 export * as AgentV2 from "./agent"
 
-import { Array, Context, Effect, Layer, Schema, Scope, Types } from "effect"
+import { Array, Context, Effect, Layer, Schema, Scope } from "effect"
+import { castDraft, enableMapSet, type Draft } from "immer"
 import { ModelV2 } from "./model"
 import { PermissionSchema } from "./permission/schema"
 import { ProviderV2 } from "./provider"
@@ -48,19 +49,21 @@ export interface Selection {
 }
 
 type Data = {
-  agents: Map<ID, Types.DeepMutable<Info>>
+  agents: Map<ID, Info>
   default?: ID
 }
 
-export type Draft = {
+export type Editor = {
   list: () => readonly Info[]
   get: (id: ID) => Info | undefined
   default: (id: ID | undefined) => void
-  update: (id: ID, fn: (agent: Types.DeepMutable<Info>) => void) => void
+  update: (id: ID, fn: (agent: Draft<Info>) => void) => void
   remove: (id: ID) => void
 }
 
-export interface Interface extends State.Transformable<Draft> {
+export interface Interface {
+  readonly transform: State.Interface<Data, Editor>["transform"]
+  readonly update: State.Interface<Data, Editor>["update"]
   readonly get: (id: ID) => Effect.Effect<Info | undefined>
   readonly default: () => Effect.Effect<Info | undefined>
   readonly resolve: (id?: ID | string) => Effect.Effect<Info | undefined>
@@ -70,19 +73,21 @@ export interface Interface extends State.Transformable<Draft> {
 
 export class Service extends Context.Service<Service, Interface>()("@opencode/v2/Agent") {}
 
+enableMapSet()
+
 export const layer = Layer.effect(
   Service,
   Effect.gen(function* () {
-    const state = State.create<Data, Draft>({
+    const state = State.create<Data, Editor>({
       initial: () => ({ agents: new Map() }),
-      draft: (draft) => ({
+      editor: (draft) => ({
         list: () => Array.fromIterable(draft.agents.values()) as Info[],
         get: (id) => draft.agents.get(id),
         default: (id) => {
           draft.default = id
         },
         update: (id, fn) => {
-          const current = draft.agents.get(id) ?? (Info.empty(id) as Types.DeepMutable<Info>)
+          const current = draft.agents.get(id) ?? castDraft(Info.empty(id))
           if (!draft.agents.has(id)) draft.agents.set(id, current)
           fn(current)
           current.id = id
@@ -108,7 +113,7 @@ export const layer = Layer.effect(
 
     return Service.of({
       transform: state.transform,
-      rebuild: state.rebuild,
+      update: state.update,
       get: Effect.fn("AgentV2.get")(function* (id) {
         return state.get().agents.get(id)
       }),

packages/core/src/catalog.ts

@@ -1,21 +1,36 @@
 export * as Catalog from "./catalog"
 
-import { Array, Context, Effect, Layer, Option, Order, pipe, Schema } from "effect"
+import { Array, Context, Effect, Layer, Option, Order, pipe, Schema, Scope, Stream } from "effect"
+import { castDraft, enableMapSet, type Draft } from "immer"
 import { ModelV2 } from "./model"
 import { ModelRequest } from "./model-request"
+import { PluginV2 } from "./plugin"
 import { ProviderV2 } from "./provider"
+import { Location } from "./location"
 import { EventV2 } from "./event"
 import { Policy } from "./policy"
 import { State } from "./state"
 import { Integration } from "./integration"
 
 export type ProviderRecord = {
-  provider: ProviderV2.MutableInfo
-  models: Map<ModelV2.ID, ModelV2.MutableInfo>
+  provider: ProviderV2.Info
+  models: Map<ModelV2.ID, ModelV2.Info>
 }
 
 export type DefaultModel = { providerID: ProviderV2.ID; modelID: ModelV2.ID }
 
+export class ProviderNotFoundError extends Schema.TaggedErrorClass<ProviderNotFoundError>()(
+  "CatalogV2.ProviderNotFound",
+  {
+    providerID: ProviderV2.ID,
+  },
+) {}
+
+export class ModelNotFoundError extends Schema.TaggedErrorClass<ModelNotFoundError>()("CatalogV2.ModelNotFound", {
+  providerID: ProviderV2.ID,
+  modelID: ModelV2.ID,
+}) {}
+
 export const PolicyActions = Schema.Literals(["provider.use"])
 
 export const Event = {
@@ -27,16 +42,16 @@ type Data = {
   defaultModel?: DefaultModel
 }
 
-export type Draft = {
+export type Editor = {
   provider: {
     list: () => readonly ProviderRecord[]
     get: (providerID: ProviderV2.ID) => ProviderRecord | undefined
-    update: (providerID: ProviderV2.ID, fn: (provider: ProviderV2.MutableInfo) => void) => void
+    update: (providerID: ProviderV2.ID, fn: (provider: Draft<ProviderV2.Info>) => void) => void
     remove: (providerID: ProviderV2.ID) => void
   }
   model: {
     get: (providerID: ProviderV2.ID, modelID: ModelV2.ID) => ModelV2.Info | undefined
-    update: (providerID: ProviderV2.ID, modelID: ModelV2.ID, fn: (model: ModelV2.MutableInfo) => void) => void
+    update: (providerID: ProviderV2.ID, modelID: ModelV2.ID, fn: (model: Draft<ModelV2.Info>) => void) => void
     remove: (providerID: ProviderV2.ID, modelID: ModelV2.ID) => void
     default: {
       get: () => DefaultModel | undefined
@@ -45,34 +60,43 @@ export type Draft = {
   }
 }
 
-export interface Interface extends State.Transformable<Draft> {
+export interface Interface {
+  readonly transform: State.Interface<Data, Editor>["transform"]
   readonly provider: {
-    readonly get: (providerID: ProviderV2.ID) => Effect.Effect<ProviderV2.Info | undefined>
+    readonly get: (providerID: ProviderV2.ID) => Effect.Effect<ProviderV2.Info, ProviderNotFoundError>
     readonly all: () => Effect.Effect<ProviderV2.Info[]>
     readonly available: () => Effect.Effect<ProviderV2.Info[]>
   }
   readonly model: {
-    readonly get: (providerID: ProviderV2.ID, modelID: ModelV2.ID) => Effect.Effect<ModelV2.Info | undefined>
+    readonly get: (
+      providerID: ProviderV2.ID,
+      modelID: ModelV2.ID,
+    ) => Effect.Effect<ModelV2.Info, ProviderNotFoundError | ModelNotFoundError>
     readonly all: () => Effect.Effect<ModelV2.Info[]>
     readonly available: () => Effect.Effect<ModelV2.Info[]>
-    readonly default: () => Effect.Effect<ModelV2.Info | undefined>
-    readonly small: (providerID: ProviderV2.ID) => Effect.Effect<ModelV2.Info | undefined>
+    readonly default: () => Effect.Effect<Option.Option<ModelV2.Info>>
+    readonly small: (providerID: ProviderV2.ID) => Effect.Effect<Option.Option<ModelV2.Info>>
   }
 }
 
 export class Service extends Context.Service<Service, Interface>()("@opencode/v2/Catalog") {}
 
+enableMapSet()
+
 export const layer = Layer.effect(
   Service,
   Effect.gen(function* () {
+    const location = yield* Location.Service
+    const plugin = yield* PluginV2.Service
     const events = yield* EventV2.Service
     const policy = yield* Policy.Service
     const integrations = yield* Integration.Service
+    const scope = yield* Scope.Scope
 
-    const available = (provider: ProviderV2.Info, integration: Integration.Info | undefined) => {
+    const available = (provider: ProviderV2.Info, integration: Integration.Info | undefined, connected: boolean) => {
       if (provider.disabled) return false
       if (typeof provider.request.body.apiKey === "string") return true
-      if (integration?.connections.length) return true
+      if (connected) return true
       return !integration
     }
 
@@ -96,26 +120,32 @@ export const layer = Layer.effect(
       })
     }
 
-    const normalizeApi = (item: ProviderV2.MutableInfo | ModelV2.MutableInfo) => {
+    function* getRecord(providerID: ProviderV2.ID) {
+      const match = state.get().providers.get(providerID)
+      if (!match) return yield* new ProviderNotFoundError({ providerID })
+      return match
+    }
+
+    const normalizeApi = (item: Draft<ProviderV2.Info> | Draft<ModelV2.Info>) => {
       if (typeof item.request.body.baseURL !== "string") return
       item.api.url = item.request.body.baseURL
       delete item.request.body.baseURL
     }
 
-    const state = State.create<Data, Draft>({
+    const state = State.create<Data, Editor>({
       initial: () => ({ providers: new Map() }),
-      draft: (draft) => {
-        const result: Draft = {
+      editor: (draft) => {
+        const result: Editor = {
           provider: {
             list: () => Array.fromIterable(draft.providers.values()) as ProviderRecord[],
             get: (providerID) => draft.providers.get(providerID),
             update: (providerID, fn) => {
               let current = draft.providers.get(providerID)
               if (!current) {
-                current = {
-                  provider: ProviderV2.Info.empty(providerID) as ProviderV2.MutableInfo,
-                  models: new Map<ModelV2.ID, ModelV2.MutableInfo>(),
-                }
+                current = castDraft({
+                  provider: ProviderV2.Info.empty(providerID),
+                  models: new Map<ModelV2.ID, ModelV2.Info>(),
+                })
                 draft.providers.set(providerID, current)
               }
               fn(current.provider)
@@ -130,14 +160,13 @@ export const layer = Layer.effect(
             update: (providerID, modelID, fn) => {
               let record = draft.providers.get(providerID)
               if (!record) {
-                record = {
-                  provider: ProviderV2.Info.empty(providerID) as ProviderV2.MutableInfo,
-                  models: new Map<ModelV2.ID, ModelV2.MutableInfo>(),
-                }
+                record = castDraft({
+                  provider: ProviderV2.Info.empty(providerID),
+                  models: new Map<ModelV2.ID, ModelV2.Info>(),
+                })
                 draft.providers.set(providerID, record)
               }
-              const model =
-                record.models.get(modelID) ?? (ModelV2.Info.empty(providerID, modelID) as ModelV2.MutableInfo)
+              const model = record.models.get(modelID) ?? castDraft(ModelV2.Info.empty(providerID, modelID))
               if (!record.models.has(modelID)) record.models.set(modelID, model)
               fn(model)
               model.id = modelID
@@ -157,7 +186,8 @@ export const layer = Layer.effect(
         }
         return result
       },
-      finalize: Effect.fn("CatalogV2.finalize")(function* (catalog) {
+      finalize: Effect.fn("CatalogV2.finalize")(function* (catalog, reason) {
+        if (reason !== "plugin.added") yield* plugin.trigger("catalog.transform", catalog, {}).pipe(Effect.asVoid)
         if (policy.hasStatements()) {
           for (const record of [...catalog.provider.list()]) {
             if ((yield* policy.evaluate("provider.use", record.provider.id, "allow")) === "deny") {
@@ -168,13 +198,25 @@ export const layer = Layer.effect(
         yield* events.publish(Event.Updated, {})
       }),
     })
+    yield* events.subscribe(PluginV2.Event.Added).pipe(
+      // Plugin registries are location scoped even though the event bus is process scoped.
+      Stream.filter(
+        (event) =>
+          event.location?.directory === location.directory && event.location.workspaceID === location.workspaceID,
+      ),
+      Stream.runForEach((event) =>
+        state.mutate((catalog) => plugin.triggerFor(event.data.id, "catalog.transform", catalog, {}), "plugin.added"),
+      ),
+      Effect.forkIn(scope, { startImmediately: true }),
+    )
+
     const result: Interface = {
       transform: state.transform,
-      rebuild: state.rebuild,
 
       provider: {
         get: Effect.fn("CatalogV2.provider.get")(function* (providerID) {
-          return state.get().providers.get(providerID)?.provider
+          const record = yield* getRecord(providerID)
+          return record.provider
         }),
 
         all: Effect.fn("CatalogV2.provider.all")(function* () {
@@ -183,18 +225,23 @@ export const layer = Layer.effect(
 
         available: Effect.fn("CatalogV2.provider.available")(function* () {
           const active = new Map((yield* integrations.list()).map((integration) => [integration.id, integration]))
+          const connections = yield* integrations.connection.list()
           return (yield* result.provider.all()).filter((provider) =>
-            available(provider, active.get(Integration.ID.make(provider.id))),
+            available(
+              provider,
+              active.get(Integration.ID.make(provider.id)),
+              connections.has(Integration.ID.make(provider.id)),
+            ),
           )
         }),
       },
 
       model: {
         get: Effect.fn("CatalogV2.model.get")(function* (providerID, modelID) {
-          const record = state.get().providers.get(providerID)
-          if (!record) return
+          const record = yield* getRecord(providerID)
           const model = record.models.get(modelID)
-          return model && projectModel(model, record.provider)
+          if (!model) return yield* new ModelNotFoundError({ providerID, modelID })
+          return projectModel(model, record.provider)
         }),
 
         all: Effect.fn("CatalogV2.model.all")(function* () {
@@ -203,7 +250,7 @@ export const layer = Layer.effect(
             Array.flatMap((record) => {
               return Array.fromIterable(record.models.values()).map((model) => projectModel(model, record.provider))
             }),
-            Array.sortWith((item) => item.time.released, Order.flip(Order.Number)),
+            Array.sortWith((item) => item.time.released.epochMilliseconds, Order.flip(Order.Number)),
           )
         }),
 
@@ -215,30 +262,31 @@ export const layer = Layer.effect(
         default: Effect.fn("CatalogV2.model.default")(function* () {
           const defaultModel = state.get().defaultModel
           if (defaultModel) {
-            const provider = yield* result.provider.get(defaultModel.providerID)
-            if (provider && (yield* result.provider.available()).some((item) => item.id === provider.id)) {
-              const model = yield* result.model.get(defaultModel.providerID, defaultModel.modelID)
-              if (model?.enabled) return model
+            const provider = yield* result.provider.get(defaultModel.providerID).pipe(Effect.option)
+            if (
+              Option.isSome(provider) &&
+              (yield* result.provider.available()).some((item) => item.id === provider.value.id)
+            ) {
+              const model = yield* result.model.get(defaultModel.providerID, defaultModel.modelID).pipe(Effect.option)
+              if (Option.isSome(model) && model.value.enabled) return model
             }
           }
 
-          return Option.getOrUndefined(
-            pipe(
-              yield* result.model.available(),
-              Array.sortWith((item) => item.time.released, Order.flip(Order.Number)),
-              Array.head,
-            ),
+          return pipe(
+            yield* result.model.available(),
+            Array.sortWith((item) => item.time.released.epochMilliseconds, Order.flip(Order.Number)),
+            Array.head,
           )
         }),
 
         small: Effect.fn("CatalogV2.model.small")(function* (providerID) {
           const record = state.get().providers.get(providerID)
-          if (!record) return
+          if (!record) return Option.none<ModelV2.Info>()
           const provider = record.provider
 
           if (providerID === ProviderV2.ID.opencode) {
             const gpt5Nano = record.models.get(ModelV2.ID.make("gpt-5-nano"))
-            if (gpt5Nano?.enabled && gpt5Nano.status === "active") return projectModel(gpt5Nano, provider)
+            if (gpt5Nano?.enabled && gpt5Nano.status === "active") return Option.some(projectModel(gpt5Nano, provider))
           }
 
           const candidates = pipe(
@@ -254,7 +302,7 @@ export const layer = Layer.effect(
             Array.map((model) => ({
               model,
               cost: model.cost[0] ? model.cost[0].input + model.cost[0].output : 999,
-              age: (Date.now() - model.time.released) / (1000 * 60 * 60 * 24 * 30),
+              age: (Date.now() - model.time.released.epochMilliseconds) / (1000 * 60 * 60 * 24 * 30),
               small: SMALL_MODEL_RE.test(`${model.id} ${model.family ?? ""} ${model.name}`.toLowerCase()),
             })),
             Array.filter((item) => item.cost > 0 && item.age <= 18),
@@ -271,12 +319,10 @@ export const layer = Layer.effect(
             )
           }
 
-          return Option.getOrUndefined(
-            pipe(
-              candidates,
-              Array.filter((item) => item.small),
-              (items) => (items.length > 0 ? pick(items) : pick(candidates)),
-            ),
+          return pipe(
+            candidates,
+            Array.filter((item) => item.small),
+            (items) => (items.length > 0 ? pick(items) : pick(candidates)),
           )
         }),
       },
@@ -290,5 +336,6 @@ const SMALL_MODEL_RE = /\b(nano|flash|lite|mini|haiku|small|fast)\b/
 
 export const locationLayer = layer.pipe(
   Layer.provideMerge(Integration.locationLayer),
+  Layer.provideMerge(PluginV2.locationLayer),
   Layer.provideMerge(Policy.locationLayer),
 )

packages/core/src/command.ts

@@ -1,6 +1,8 @@
 export * as CommandV2 from "./command"
 
-import { Context, Effect, Layer, Schema, Types } from "effect"
+import { Context, Effect, Layer, Schema } from "effect"
+import { castDraft, type Draft } from "immer"
+import { LayerNode } from "./effect/layer-node"
 import { ModelV2 } from "./model"
 import { State } from "./state"
 
@@ -14,17 +16,19 @@ export class Info extends Schema.Class<Info>("CommandV2.Info")({
 }) {}
 
 export type Data = {
-  commands: Map<string, Types.DeepMutable<Info>>
+  commands: Map<string, Info>
 }
 
-export type Draft = {
+export type Editor = {
   list: () => readonly Info[]
   get: (name: string) => Info | undefined
-  update: (name: string, update: (command: Types.DeepMutable<Info>) => void) => void
+  update: (name: string, update: (command: Draft<Info>) => void) => void
   remove: (name: string) => void
 }
 
-export interface Interface extends State.Transformable<Draft> {
+export interface Interface {
+  readonly transform: State.Interface<Data, Editor>["transform"]
+  readonly update: State.Interface<Data, Editor>["update"]
   readonly get: (name: string) => Effect.Effect<Info | undefined>
   readonly list: () => Effect.Effect<Info[]>
 }
@@ -34,13 +38,13 @@ export class Service extends Context.Service<Service, Interface>()("@opencode/v2
 export const layer = Layer.effect(
   Service,
   Effect.sync(() => {
-    const state = State.create<Data, Draft>({
+    const state = State.create<Data, Editor>({
       initial: () => ({ commands: new Map() }),
-      draft: (draft) => ({
+      editor: (draft) => ({
         list: () => Array.from(draft.commands.values()) as Info[],
         get: (name) => draft.commands.get(name),
         update: (name, update) => {
-          const current = draft.commands.get(name) ?? (new Info({ name, template: "" }) as Types.DeepMutable<Info>)
+          const current = draft.commands.get(name) ?? castDraft(new Info({ name, template: "" }))
           if (!draft.commands.has(name)) draft.commands.set(name, current)
           update(current)
           current.name = name
@@ -52,7 +56,7 @@ export const layer = Layer.effect(
     })
 
     return Service.of({
-      rebuild: state.rebuild,
+      update: state.update,
       transform: state.transform,
       get: Effect.fn("CommandV2.get")(function* (name) {
         return state.get().commands.get(name)
@@ -65,3 +69,4 @@ export const layer = Layer.effect(
 )
 
 export const locationLayer = layer
+export const node = LayerNode.make(layer, [])

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

@@ -1,6 +1,5 @@
 export * as ConfigAgentPlugin from "./agent"
 
-import { define } from "@opencode-ai/plugin/v2/effect"
 import path from "path"
 import { Effect, Option, Schema } from "effect"
 import { AgentV2 } from "../../agent"
@@ -9,6 +8,7 @@ import { ConfigAgent } from "../agent"
 import { ConfigMarkdown } from "../markdown"
 import { FSUtil } from "../../fs-util"
 import { ModelV2 } from "../../model"
+import { PluginV2 } from "../../plugin"
 import { ConfigAgentV1 } from "../../v1/config/agent"
 import { ConfigMigrateV1 } from "../../v1/config/migrate"
 
@@ -33,70 +33,70 @@ const agentKeys = new Set([
   "permissions",
 ])
 
-export const Plugin = define({
-  id: "config-agent",
-  effect: Effect.fn(function* (ctx) {
+export const Plugin = PluginV2.define({
+  id: PluginV2.ID.make("config-agent"),
+  effect: Effect.gen(function* () {
+    const agent = yield* AgentV2.Service
     const config = yield* Config.Service
     const fs = yield* FSUtil.Service
-    yield* ctx.agent.transform(
-      Effect.fn(function* (draft) {
-        const documents = yield* Effect.forEach(yield* config.entries(), (entry) => {
-          if (entry.type === "document") return Effect.succeed([entry])
-          return Effect.gen(function* () {
-            const files = yield* discover(fs, entry.path)
-            return yield* Effect.forEach(files, (file) =>
-              fs.readFileStringSafe(file.filepath).pipe(
-                Effect.map((content) => content && decode(file, content)),
-                Effect.catch(() => Effect.succeed(undefined)),
-              ),
-            ).pipe(
-              Effect.map((documents) =>
-                documents.filter((document): document is Config.Document => document !== undefined),
-              ),
-            )
-          })
-        }).pipe(Effect.map((documents) => documents.flat()))
-        const global = documents.flatMap((document) => document.info.permissions ?? [])
-        const configuredDefault = Config.latest(documents, "default_agent")
-        if (configuredDefault !== undefined) draft.default(AgentV2.ID.make(configuredDefault))
-        for (const current of draft.list()) {
-          draft.update(current.id, (agent) => agent.permissions.push(...global))
-        }
+    const documents = yield* Effect.forEach(yield* config.entries(), (entry) => {
+      if (entry.type === "document") return Effect.succeed([entry])
+      return Effect.gen(function* () {
+        const files = yield* discover(fs, entry.path)
+        return yield* Effect.forEach(files, (file) =>
+          fs.readFileStringSafe(file.filepath).pipe(
+            Effect.map((content) => content && decode(file, content)),
+            Effect.catch(() => Effect.succeed(undefined)),
+          ),
+        ).pipe(
+          Effect.map((documents) =>
+            documents.filter((document): document is Config.Document => document !== undefined),
+          ),
+        )
+      })
+    }).pipe(Effect.map((documents) => documents.flat()))
 
-        for (const document of documents) {
-          for (const [id, item] of Object.entries(document.info.agents ?? {})) {
-            const agentID = AgentV2.ID.make(id)
-            if (item.disabled) {
-              draft.remove(agentID)
-              continue
-            }
+    yield* agent.update((editor) => {
+      const global = documents.flatMap((document) => document.info.permissions ?? [])
+      const configuredDefault = Config.latest(documents, "default_agent")
+      if (configuredDefault !== undefined) editor.default(AgentV2.ID.make(configuredDefault))
+      for (const current of editor.list()) {
+        editor.update(current.id, (agent) => agent.permissions.push(...global))
+      }
 
-            const exists = draft.get(agentID) !== undefined
-            draft.update(agentID, (agent) => {
-              if (!exists) agent.permissions.push(...global)
-              if (item.model !== undefined) {
-                const model = ModelV2.parse(item.model)
-                agent.model = { id: model.modelID, providerID: model.providerID, variant: agent.model?.variant }
-              }
-              if (item.variant !== undefined && agent.model !== undefined) {
-                agent.model.variant = ModelV2.VariantID.make(item.variant)
-              }
-              if (item.request !== undefined) {
-                Object.assign(agent.request.headers, item.request.headers ?? {})
-                Object.assign(agent.request.body, item.request.body ?? {})
-              }
-              if (item.system !== undefined) agent.system = item.system
-              if (item.description !== undefined) agent.description = item.description
-              if (item.mode !== undefined) agent.mode = item.mode
-              if (item.hidden !== undefined) agent.hidden = item.hidden
-              if (item.color !== undefined) agent.color = item.color
-              if (item.steps !== undefined) agent.steps = item.steps
-              if (item.permissions !== undefined) agent.permissions.push(...item.permissions)
-            })
+      for (const document of documents) {
+        for (const [id, item] of Object.entries(document.info.agents ?? {})) {
+          const agentID = AgentV2.ID.make(id)
+          if (item.disabled) {
+            editor.remove(agentID)
+            continue
           }
+
+          const exists = editor.get(agentID) !== undefined
+          editor.update(agentID, (agent) => {
+            if (!exists) agent.permissions.push(...global)
+            if (item.model !== undefined) {
+              const model = ModelV2.parse(item.model)
+              agent.model = { id: model.modelID, providerID: model.providerID, variant: agent.model?.variant }
+            }
+            if (item.variant !== undefined && agent.model !== undefined) {
+              agent.model.variant = ModelV2.VariantID.make(item.variant)
+            }
+            if (item.request !== undefined) {
+              Object.assign(agent.request.headers, item.request.headers ?? {})
+              Object.assign(agent.request.body, item.request.body ?? {})
+            }
+            if (item.system !== undefined) agent.system = item.system
+            if (item.description !== undefined) agent.description = item.description
+            if (item.mode !== undefined) agent.mode = item.mode
+            if (item.hidden !== undefined) agent.hidden = item.hidden
+            if (item.color !== undefined) agent.color = item.color
+            if (item.steps !== undefined) agent.steps = item.steps
+            if (item.permissions !== undefined) agent.permissions.push(...item.permissions)
+          })
         }
-      }),
-    )
+      }
+    })
   }),
 })
 

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

@@ -1,51 +1,52 @@
 export * as ConfigCommandPlugin from "./command"
 
-import { define } from "@opencode-ai/plugin/v2/effect"
 import path from "path"
 import { Effect, Option, Schema } from "effect"
 import { CommandV2 } from "../../command"
 import { Config } from "../../config"
 import { FSUtil } from "../../fs-util"
 import { ModelV2 } from "../../model"
+import { PluginV2 } from "../../plugin"
 import { ConfigCommand } from "../command"
 import { ConfigMarkdown } from "../markdown"
 
 const decodeCommand = Schema.decodeUnknownOption(ConfigCommand.Info)
 
-export const Plugin = define({
-  id: "config-command",
-  effect: Effect.fn(function* (ctx) {
+export const Plugin = PluginV2.define({
+  id: PluginV2.ID.make("config-command"),
+  effect: Effect.gen(function* () {
+    const command = yield* CommandV2.Service
     const config = yield* Config.Service
     const fs = yield* FSUtil.Service
-    yield* ctx.command.transform(
-      Effect.fn(function* (draft) {
-        const documents = yield* Effect.forEach(yield* config.entries(), (entry) => {
-          if (entry.type === "document") return Effect.succeed([{ commands: entry.info.commands }])
-          return loadDirectory(fs, entry.path).pipe(
-            Effect.map((commands) => [
-              { commands: Object.fromEntries(commands.map((command) => [command.name, command.info])) },
-            ]),
-          )
-        }).pipe(Effect.map((documents) => documents.flat()))
-        for (const document of documents) {
-          for (const [name, command] of Object.entries(document.commands ?? {})) {
-            draft.update(name, (item) => {
-              item.template = command.template
-              if (command.description !== undefined) item.description = command.description
-              if (command.agent !== undefined) item.agent = command.agent
-              if (command.model !== undefined) {
-                const model = ModelV2.parse(command.model)
-                item.model = { id: model.modelID, providerID: model.providerID, variant: item.model?.variant }
-              }
-              if (command.variant !== undefined && item.model !== undefined) {
-                item.model.variant = ModelV2.VariantID.make(command.variant)
-              }
-              if (command.subtask !== undefined) item.subtask = command.subtask
-            })
-          }
+    const transform = yield* command.transform()
+    const documents = yield* Effect.forEach(yield* config.entries(), (entry) => {
+      if (entry.type === "document") return Effect.succeed([{ commands: entry.info.commands }])
+      return loadDirectory(fs, entry.path).pipe(
+        Effect.map((commands) => [
+          { commands: Object.fromEntries(commands.map((command) => [command.name, command.info])) },
+        ]),
+      )
+    }).pipe(Effect.map((documents) => documents.flat()))
+
+    yield* transform((editor) => {
+      for (const document of documents) {
+        for (const [name, command] of Object.entries(document.commands ?? {})) {
+          editor.update(name, (item) => {
+            item.template = command.template
+            if (command.description !== undefined) item.description = command.description
+            if (command.agent !== undefined) item.agent = command.agent
+            if (command.model !== undefined) {
+              const model = ModelV2.parse(command.model)
+              item.model = { id: model.modelID, providerID: model.providerID, variant: item.model?.variant }
+            }
+            if (command.variant !== undefined && item.model !== undefined) {
+              item.model.variant = ModelV2.VariantID.make(command.variant)
+            }
+            if (command.subtask !== undefined) item.subtask = command.subtask
+          })
         }
-      }),
-    )
+      }
+    })
   }),
 })
 

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

@@ -1,124 +1,123 @@
 export * as ConfigProviderPlugin from "./provider"
 
-import { define } from "@opencode-ai/plugin/v2/effect"
 import { Effect } from "effect"
+import { Catalog } from "../../catalog"
 import { Config } from "../../config"
+import { Integration } from "../../integration"
 import { ModelV2 } from "../../model"
 import { ModelRequest } from "../../model-request"
+import { PluginV2 } from "../../plugin"
 import { ProviderV2 } from "../../provider"
 
-export const Plugin = define({
-  id: "config-provider",
-  effect: Effect.fn(function* (ctx) {
+export const Plugin = PluginV2.define({
+  id: PluginV2.ID.make("config-provider"),
+  effect: Effect.gen(function* () {
+    const catalog = yield* Catalog.Service
     const config = yield* Config.Service
-    yield* ctx.integration.transform(
-      Effect.fn(function* (integrations) {
-        const files = (yield* config.entries()).filter((entry): entry is Config.Document => entry.type === "document")
-        const configuredIntegrations = new Set(
-          files.flatMap((file) =>
-            Object.entries(file.info.providers ?? {}).flatMap(([id, provider]) =>
-              provider.env === undefined ? [] : [id],
-            ),
-          ),
-        )
-        for (const file of files) {
-          for (const [id, item] of Object.entries(file.info.providers ?? {})) {
-            const integrationID = id
-            if (!configuredIntegrations.has(id) && !integrations.get(integrationID)) continue
-            integrations.update(integrationID, (integration) => {
-              integration.name = item.name ?? integration.name
+    const integrations = yield* Integration.Service
+    const transform = yield* catalog.transform()
+    const integrationTransform = yield* integrations.transform()
+    const entries = yield* config.entries()
+    const files = entries.filter((entry): entry is Config.Document => entry.type === "document")
+    const configuredIntegrations = new Set(
+      files.flatMap((file) =>
+        Object.entries(file.info.providers ?? {}).flatMap(([id, provider]) => (provider.env === undefined ? [] : [id])),
+      ),
+    )
+    yield* integrationTransform((integrations) => {
+      for (const file of files) {
+        for (const [id, item] of Object.entries(file.info.providers ?? {})) {
+          const integrationID = Integration.ID.make(id)
+          if (!configuredIntegrations.has(id) && !integrations.get(integrationID)) continue
+          integrations.update(integrationID, (integration) => {
+            integration.name = item.name ?? integration.name
+          })
+          if (item.env !== undefined) {
+            integrations.method.update({
+              integrationID,
+              method: { type: "env", names: [...item.env] },
             })
-            if (item.env !== undefined) {
-              integrations.method.update({
-                integrationID,
-                method: { type: "env", names: [...item.env] },
-              })
-            }
           }
         }
-      }),
-    )
+      }
+    })
 
-    yield* ctx.catalog.transform(
-      Effect.fn(function* (catalog) {
-        const entries = yield* config.entries()
-        const files = entries.filter((entry): entry is Config.Document => entry.type === "document")
-        const configuredDefault = Config.latest(entries, "model")
-        if (configuredDefault !== undefined) {
-          const model = ModelV2.parse(configuredDefault)
-          catalog.model.default.set(model.providerID, model.modelID)
-        }
-        for (const file of files) {
-          for (const [id, item] of Object.entries(file.info.providers ?? {})) {
-            const providerID = id
-            catalog.provider.update(providerID, (provider) => {
-              if (item.name !== undefined) provider.name = item.name
-              if (item.api !== undefined) provider.api = { ...item.api }
-              if (item.request !== undefined) {
-                Object.assign(provider.request.headers, item.request.headers)
-                Object.assign(provider.request.body, item.request.body)
+    yield* transform((catalog) => {
+      const configuredDefault = Config.latest(entries, "model")
+      if (configuredDefault !== undefined) {
+        const model = ModelV2.parse(configuredDefault)
+        catalog.model.default.set(model.providerID, model.modelID)
+      }
+      for (const file of files) {
+        for (const [id, item] of Object.entries(file.info.providers ?? {})) {
+          const providerID = ProviderV2.ID.make(id)
+          catalog.provider.update(providerID, (provider) => {
+            if (item.name !== undefined) provider.name = item.name
+            if (item.api !== undefined) provider.api = { ...item.api }
+            if (item.request !== undefined) {
+              Object.assign(provider.request.headers, item.request.headers)
+              Object.assign(provider.request.body, item.request.body)
+            }
+          })
+          const providerApi = catalog.provider.get(providerID)?.provider.api
+          const providerPackage = providerApi?.type === "aisdk" ? providerApi.package : undefined
+
+          for (const [id, config] of Object.entries(item.models ?? {})) {
+            catalog.model.update(providerID, ModelV2.ID.make(id), (model) => {
+              if (config.family !== undefined) model.family = config.family
+              if (config.name !== undefined) model.name = config.name
+              if (config.api !== undefined) model.api = { ...model.api, ...config.api }
+              const packageName = model.api.type === "aisdk" ? model.api.package : providerPackage
+              if (config.capabilities !== undefined) {
+                model.capabilities = {
+                  tools: config.capabilities.tools,
+                  input: [...config.capabilities.input],
+                  output: [...config.capabilities.output],
+                }
               }
-            })
-            const providerApi = catalog.provider.get(providerID)?.provider.api
-            const providerPackage = providerApi?.type === "aisdk" ? providerApi.package : undefined
-
-            for (const [id, config] of Object.entries(item.models ?? {})) {
-              catalog.model.update(providerID, id, (model) => {
-                if (config.family !== undefined) model.family = config.family
-                if (config.name !== undefined) model.name = config.name
-                if (config.api !== undefined) model.api = { ...model.api, ...config.api }
-                const packageName = model.api.type === "aisdk" ? model.api.package : providerPackage
-                if (config.capabilities !== undefined) {
-                  model.capabilities = {
-                    tools: config.capabilities.tools,
-                    input: [...config.capabilities.input],
-                    output: [...config.capabilities.output],
-                  }
-                }
-                if (config.request !== undefined) {
-                  ModelRequest.assign(model.request, {
-                    headers: config.request.headers,
-                    ...ModelRequest.normalizeAiSdkOptions(packageName, config.request.body ?? {}),
-                  })
-                  if (config.request.variant !== undefined) model.request.variant = config.request.variant
-                }
-                if (config.variants !== undefined) {
-                  for (const variant of config.variants) {
-                    let existing = model.variants.find((item) => item.id === variant.id)
-                    if (!existing) {
-                      existing = {
-                        id: variant.id,
-                        headers: {},
-                        body: {},
-                        generation: {},
-                        options: {},
-                      }
-                      model.variants.push(existing)
+              if (config.request !== undefined) {
+                ModelRequest.assign(model.request, {
+                  headers: config.request.headers,
+                  ...ModelRequest.normalizeAiSdkOptions(packageName, config.request.body ?? {}),
+                })
+                if (config.request.variant !== undefined) model.request.variant = config.request.variant
+              }
+              if (config.variants !== undefined) {
+                for (const variant of config.variants) {
+                  let existing = model.variants.find((item) => item.id === variant.id)
+                  if (!existing) {
+                    existing = {
+                      id: variant.id,
+                      headers: {},
+                      body: {},
+                      generation: {},
+                      options: {},
                     }
-                    ModelRequest.assign(existing, {
-                      headers: variant.headers,
-                      ...ModelRequest.normalizeAiSdkOptions(packageName, variant.body ?? {}),
-                    })
+                    model.variants.push(existing)
                   }
+                  ModelRequest.assign(existing, {
+                    headers: variant.headers,
+                    ...ModelRequest.normalizeAiSdkOptions(packageName, variant.body ?? {}),
+                  })
                 }
-                if (config.cost !== undefined) {
-                  model.cost = (Array.isArray(config.cost) ? config.cost : [config.cost]).map((cost) => ({
-                    tier: cost.tier && { ...cost.tier },
-                    input: cost.input,
-                    output: cost.output,
-                    cache: {
-                      read: cost.cache?.read ?? 0,
-                      write: cost.cache?.write ?? 0,
-                    },
-                  }))
-                }
-                if (config.disabled !== undefined) model.enabled = !config.disabled
-                if (config.limit !== undefined) model.limit = { ...model.limit, ...config.limit }
-              })
-            }
+              }
+              if (config.cost !== undefined) {
+                model.cost = (Array.isArray(config.cost) ? config.cost : [config.cost]).map((cost) => ({
+                  tier: cost.tier && { ...cost.tier },
+                  input: cost.input,
+                  output: cost.output,
+                  cache: {
+                    read: cost.cache?.read ?? 0,
+                    write: cost.cache?.write ?? 0,
+                  },
+                }))
+              }
+              if (config.disabled !== undefined) model.enabled = !config.disabled
+              if (config.limit !== undefined) model.limit = { ...model.limit, ...config.limit }
+            })
           }
         }
-      }),
-    )
+      }
+    })
   }),
 })

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

@@ -1,52 +1,57 @@
 export * as ConfigReferencePlugin from "./reference"
 
-import { define } from "@opencode-ai/plugin/v2/effect"
 import path from "path"
 import { Effect } from "effect"
 import { Config } from "../../config"
 import { ConfigReference } from "../reference"
+import { Global } from "../../global"
+import { Location } from "../../location"
+import { PluginV2 } from "../../plugin"
 import { Reference } from "../../reference"
 import { AbsolutePath } from "../../schema"
 
-export const Plugin = define({
-  id: "core/config-reference",
-  effect: Effect.fn(function* (ctx) {
+export const Plugin = {
+  id: PluginV2.ID.make("core/config-reference"),
+  effect: Effect.gen(function* () {
     const config = yield* Config.Service
-    yield* ctx.reference.transform(
-      Effect.fn(function* (draft) {
-        const entries = new Map<string, Reference.Source>()
-        for (const doc of (yield* config.entries()).filter(
-          (entry): entry is Config.Document => entry.type === "document",
-        )) {
-          const directory = doc.path ? path.dirname(doc.path) : ctx.location.directory
-          for (const [name, entry] of Object.entries(doc.info.references ?? {})) {
-            if (!validAlias(name)) continue
-            entries.set(
-              name,
-              local(entry)
-                ? new Reference.LocalSource({
-                    type: "local",
-                    path: AbsolutePath.make(
-                      localPath(directory, ctx.path.home, typeof entry === "string" ? entry : entry.path),
-                    ),
-                    description: typeof entry === "string" ? undefined : entry.description,
-                    hidden: typeof entry === "string" ? undefined : entry.hidden,
-                  })
-                : new Reference.GitSource({
-                    type: "git",
-                    repository: typeof entry === "string" ? entry : entry.repository,
-                    branch: typeof entry === "string" ? undefined : entry.branch,
-                    description: typeof entry === "string" ? undefined : entry.description,
-                    hidden: typeof entry === "string" ? undefined : entry.hidden,
-                  }),
-            )
-          }
-        }
-        for (const [name, source] of entries) draft.add(name, source)
-      }),
-    )
+    const global = yield* Global.Service
+    const location = yield* Location.Service
+    const references = yield* Reference.Service
+    const update = yield* references.transform()
+    const entries = new Map<string, Reference.Source>()
+    for (const doc of (yield* config.entries()).filter(
+      (entry): entry is Config.Document => entry.type === "document",
+    )) {
+      const directory = doc.path ? path.dirname(doc.path) : location.directory
+      for (const [name, entry] of Object.entries(doc.info.references ?? {})) {
+        if (!validAlias(name)) continue
+        entries.set(
+          name,
+          local(entry)
+            ? new Reference.LocalSource({
+                type: "local",
+                path: AbsolutePath.make(
+                  localPath(directory, global.home, typeof entry === "string" ? entry : entry.path),
+                ),
+                description: typeof entry === "string" ? undefined : entry.description,
+                hidden: typeof entry === "string" ? undefined : entry.hidden,
+              })
+            : new Reference.GitSource({
+                type: "git",
+                repository: typeof entry === "string" ? entry : entry.repository,
+                branch: typeof entry === "string" ? undefined : entry.branch,
+                description: typeof entry === "string" ? undefined : entry.description,
+                hidden: typeof entry === "string" ? undefined : entry.hidden,
+              }),
+        )
+      }
+    }
+
+    yield* update((editor) => {
+      for (const [name, source] of entries) editor.add(name, source)
+    })
   }),
-})
+}
 
 function validAlias(name: string) {
   return name.length > 0 && !/[\/\s`,]/.test(name)

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

@@ -1,45 +1,48 @@
 export * as ConfigSkillPlugin from "./skill"
 
-import { define } from "@opencode-ai/plugin/v2/effect"
 import path from "path"
 import { Effect } from "effect"
 import { Config } from "../../config"
+import { Global } from "../../global"
+import { Location } from "../../location"
+import { PluginV2 } from "../../plugin"
 import { AbsolutePath } from "../../schema"
 import { SkillV2 } from "../../skill"
 
-export const Plugin = define({
-  id: "config-skill",
-  effect: Effect.fn(function* (ctx) {
+export const Plugin = PluginV2.define({
+  id: PluginV2.ID.make("config-skill"),
+  effect: Effect.gen(function* () {
     const config = yield* Config.Service
-    yield* ctx.skill.transform(
-      Effect.fn(function* (draft) {
-        const entries = yield* config.entries()
-        const directories = entries.flatMap((entry) => (entry.type === "directory" ? [entry.path] : []))
-        const items = entries.flatMap((entry) => (entry.type === "document" ? (entry.info.skills ?? []) : []))
-        for (const directory of directories) {
-          draft.source(
-            new SkillV2.DirectorySource({ type: "directory", path: AbsolutePath.make(path.join(directory, "skill")) }),
-          )
-          draft.source(
-            new SkillV2.DirectorySource({ type: "directory", path: AbsolutePath.make(path.join(directory, "skills")) }),
-          )
+    const global = yield* Global.Service
+    const location = yield* Location.Service
+    const skill = yield* SkillV2.Service
+    const transform = yield* skill.transform()
+    const entries = yield* config.entries()
+    const directories = entries.flatMap((entry) => (entry.type === "directory" ? [entry.path] : []))
+    const items = entries.flatMap((entry) => (entry.type === "document" ? (entry.info.skills ?? []) : []))
+
+    yield* transform((editor) => {
+      for (const directory of directories) {
+        editor.source(
+          new SkillV2.DirectorySource({ type: "directory", path: AbsolutePath.make(path.join(directory, "skill")) }),
+        )
+        editor.source(
+          new SkillV2.DirectorySource({ type: "directory", path: AbsolutePath.make(path.join(directory, "skills")) }),
+        )
+      }
+      for (const item of items) {
+        if (URL.canParse(item) && /^(https?:)$/.test(new URL(item).protocol)) {
+          editor.source(new SkillV2.UrlSource({ type: "url", url: item }))
+          continue
         }
-        for (const item of items) {
-          if (URL.canParse(item) && /^(https?:)$/.test(new URL(item).protocol)) {
-            draft.source(new SkillV2.UrlSource({ type: "url", url: item }))
-            continue
-          }
-          const expanded = item.startsWith("~/") ? path.join(ctx.path.home, item.slice(2)) : item
-          draft.source(
-            new SkillV2.DirectorySource({
-              type: "directory",
-              path: AbsolutePath.make(
-                path.isAbsolute(expanded) ? expanded : path.join(ctx.location.directory, expanded),
-              ),
-            }),
-          )
-        }
-      }),
-    )
+        const expanded = item.startsWith("~/") ? path.join(global.home, item.slice(2)) : item
+        editor.source(
+          new SkillV2.DirectorySource({
+            type: "directory",
+            path: AbsolutePath.make(path.isAbsolute(expanded) ? expanded : path.join(location.directory, expanded)),
+          }),
+        )
+      }
+    })
   }),
 })

packages/core/src/credential.ts

@@ -29,33 +29,33 @@ export class Key extends Schema.Class<Key>("Credential.Key")({
   metadata: Schema.optional(Schema.Record(Schema.String, Schema.String)),
 }) {}
 
-export const Value = Schema.Union([OAuth, Key])
+export const Info = Schema.Union([OAuth, Key])
   .pipe(Schema.toTaggedUnion("type"))
-  .annotate({ identifier: "Credential.Value" })
-export type Value = Schema.Schema.Type<typeof Value>
+  .annotate({ identifier: "Credential.Info" })
+export type Info = Schema.Schema.Type<typeof Info>
 
-export class Info extends Schema.Class<Info>("Credential.Info")({
+export class Stored extends Schema.Class<Stored>("Credential.Stored")({
   id: ID,
   integrationID: IntegrationSchema.ID,
   label: Schema.String,
-  value: Value,
+  value: Info,
 }) {}
 
 export interface Interface {
   /** Returns every stored credential. */
-  readonly all: () => Effect.Effect<Info[]>
+  readonly all: () => Effect.Effect<Stored[]>
   /** Returns stored credentials belonging to one integration. */
-  readonly list: (integrationID: IntegrationSchema.ID) => Effect.Effect<Info[]>
+  readonly list: (integrationID: IntegrationSchema.ID) => Effect.Effect<Stored[]>
   /** Returns one stored credential by ID. */
-  readonly get: (id: ID) => Effect.Effect<Info | undefined>
+  readonly get: (id: ID) => Effect.Effect<Stored | undefined>
   /** Replaces any credential for an integration and returns the new record. */
   readonly create: (input: {
     readonly integrationID: IntegrationSchema.ID
-    readonly value: Value
+    readonly value: Info
     readonly label?: string
-  }) => Effect.Effect<Info>
+  }) => Effect.Effect<Stored>
   /** Updates the label or secret value of a stored credential. */
-  readonly update: (id: ID, updates: Partial<Pick<Info, "label" | "value">>) => Effect.Effect<void>
+  readonly update: (id: ID, updates: Partial<Pick<Stored, "label" | "value">>) => Effect.Effect<void>
   /** Removes a stored credential. */
   readonly remove: (id: ID) => Effect.Effect<void>
 }
@@ -66,10 +66,10 @@ export const layer = Layer.effect(
   Service,
   Effect.gen(function* () {
     const { db } = yield* Database.Service
-    const decode = Schema.decodeUnknownSync(Value)
+    const decode = Schema.decodeUnknownSync(Info)
     const stored = (row: typeof CredentialTable.$inferSelect) => {
       if (!row.integration_id) return
-      return new Info({
+      return new Stored({
         id: row.id,
         integrationID: row.integration_id,
         label: row.label,
@@ -106,7 +106,7 @@ export const layer = Layer.effect(
         return row ? stored(row) : undefined
       }),
       create: Effect.fn("Credential.create")(function* (input) {
-        const credential = new Info({
+        const credential = new Stored({
           id: ID.create(),
           integrationID: input.integrationID,
           label: input.label ?? "default",

packages/core/src/credential/sql.ts

@@ -7,7 +7,7 @@ export const CredentialTable = sqliteTable("credential", {
   id: text().$type<Credential.ID>().primaryKey(),
   integration_id: text().$type<IntegrationSchema.ID>(),
   label: text().notNull(),
-  value: text({ mode: "json" }).$type<Credential.Value>().notNull(),
+  value: text({ mode: "json" }).$type<Credential.Info>().notNull(),
   connector_id: text(),
   method_id: text(),
   active: integer({ mode: "boolean" }),

packages/core/src/database/migration.gen.ts

@@ -37,6 +37,5 @@ export const migrations = (
     import("./migration/20260611035744_credential"),
     import("./migration/20260611192811_lush_chimera"),
     import("./migration/20260612174303_project_dir_strategy"),
-    import("./migration/20260622142730_simplify_session_context_epoch"),
   ])
 ).map((module) => module.default) satisfies DatabaseMigration.Migration[]

packages/core/src/database/migration/20260622142730_simplify_session_context_epoch.ts

@@ -1,13 +0,0 @@
-import { Effect } from "effect"
-import type { DatabaseMigration } from "../migration"
-
-export default {
-  id: "20260622142730_simplify_session_context_epoch",
-  up(tx) {
-    return Effect.gen(function* () {
-      yield* tx.run(`ALTER TABLE \`session_context_epoch\` DROP COLUMN \`agent\`;`)
-      yield* tx.run(`ALTER TABLE \`session_context_epoch\` DROP COLUMN \`replacement_seq\`;`)
-      yield* tx.run(`ALTER TABLE \`session_context_epoch\` DROP COLUMN \`revision\`;`)
-    })
-  },
-} satisfies DatabaseMigration.Migration

packages/core/src/database/schema.gen.ts

@@ -149,8 +149,11 @@ export default {
         CREATE TABLE \`session_context_epoch\` (
           \`session_id\` text PRIMARY KEY,
           \`baseline\` text NOT NULL,
+          \`agent\` text DEFAULT 'build' NOT NULL,
           \`snapshot\` text NOT NULL,
           \`baseline_seq\` integer NOT NULL,
+          \`replacement_seq\` integer,
+          \`revision\` integer DEFAULT 0 NOT NULL,
           CONSTRAINT \`fk_session_context_epoch_session_id_session_id_fk\` FOREIGN KEY (\`session_id\`) REFERENCES \`session\`(\`id\`) ON DELETE CASCADE
         );
       `)

packages/core/src/event.ts

@@ -5,7 +5,7 @@ import { and, asc, eq, gt } from "drizzle-orm"
 import { Database } from "./database/database"
 import { EventSequenceTable, EventTable } from "./event/sql"
 import { Location } from "./location"
-import { externalID, type ExternalID, withStatics } from "./schema"
+import { externalID, type ExternalID, NonNegativeInt, withStatics } from "./schema"
 import { Identifier } from "./util/identifier"
 import { LayerNode } from "./effect/layer-node"
 import { isDeepStrictEqual } from "node:util"
@@ -19,9 +19,16 @@ export const ID = Schema.String.check(Schema.isStartsWith("evt_")).pipe(
 )
 export type ID = typeof ID.Type
 
+/**
+ * Durable aggregate continuation position for embedded replay streams.
+ * TODO: Decide whether a future HTTP / SDK surface should expose an opaque cursor instead.
+ */
+export const Cursor = NonNegativeInt.pipe(Schema.brand("EventV2.Cursor"))
+export type Cursor = typeof Cursor.Type
+
 export type Definition<Type extends string = string, DataSchema extends Schema.Top = Schema.Top> = {
   readonly type: Type
-  readonly durable?: {
+  readonly sync?: {
     readonly version: number
     readonly aggregate: string
   }
@@ -34,16 +41,20 @@ export type Payload<D extends Definition = Definition> = {
   readonly id: ID
   readonly type: D["type"]
   readonly data: Data<D>
-  readonly durable?: {
-    readonly aggregateID: string
-    readonly seq: number
-    readonly version: number
-  }
+  /** Durable aggregate order, populated while synchronized events are projected. */
+  readonly seq?: number
+  readonly version?: number
   readonly location?: Location.Ref
   readonly metadata?: Record<string, unknown>
+  /** Internal replay marker for projectors that own non-replicated operational state. */
+  readonly replay?: boolean
 }
 
-export type Subscriber<D extends Definition = Definition> = (event: Payload<D>) => Effect.Effect<void>
+export type Projector<D extends Definition = Definition> = (event: Payload<D>) => Effect.Effect<void>
+type AnyProjector = (event: Payload) => Effect.Effect<void>
+export type CommitGuard = (event: Payload) => Effect.Effect<void>
+export type Listener = (event: Payload) => Effect.Effect<void>
+export type Sync = (event: Payload) => Effect.Effect<void>
 export type Unsubscribe = Effect.Effect<void>
 
 export type SerializedEvent = {
@@ -54,8 +65,13 @@ export type SerializedEvent = {
   readonly data: Record<string, unknown>
 }
 
-export class InvalidDurableEventError extends Schema.TaggedErrorClass<InvalidDurableEventError>()(
-  "EventV2.InvalidDurableEvent",
+export type CursorEvent<E extends Payload = Payload> = {
+  readonly cursor: Cursor
+  readonly event: E
+}
+
+export class InvalidSyncEventError extends Schema.TaggedErrorClass<InvalidSyncEventError>()(
+  "EventV2.InvalidSyncEvent",
   {
     type: Schema.String,
     message: Schema.String,
@@ -67,11 +83,19 @@ export function versionedType(type: string, version: number) {
 }
 
 export const registry = new Map<string, Definition>()
-const durableRegistry = new Map<string, Definition>()
+type SyncDefinition = Definition & {
+  readonly sync: NonNullable<Definition["sync"]>
+  readonly encode: (data: unknown) => unknown
+  readonly decode: (data: unknown) => unknown
+}
+const syncRegistry = new Map<string, SyncDefinition>()
+
+// Synchronized events cross a JSON boundary, so their data schemas must encode and decode without services.
+const syncCodec = (definition: Definition) => definition.data as Schema.Codec<unknown, unknown, never, never>
 
 export function define<const Type extends string, Fields extends Schema.Struct.Fields>(input: {
   readonly type: Type
-  readonly durable?: {
+  readonly sync?: {
     readonly version: number
     readonly aggregate: string
   }
@@ -82,25 +106,28 @@ export function define<const Type extends string, Fields extends Schema.Struct.F
     id: ID,
     metadata: Schema.optional(Schema.Record(Schema.String, Schema.Unknown)),
     type: Schema.Literal(input.type),
-    durable: Schema.optional(Schema.Struct({ aggregateID: Schema.String, seq: Schema.Number, version: Schema.Number })),
+    version: Schema.optional(Schema.Number),
     location: Schema.optional(Location.Ref),
     data: Data,
   }).annotate({ identifier: input.type })
 
   const definition = Object.assign(Payload, {
     type: input.type,
-    ...(input.durable === undefined ? {} : { durable: input.durable }),
+    ...(input.sync === undefined ? {} : { sync: input.sync }),
     data: Data,
   })
   const existing = registry.get(input.type)
-  if (
-    input.durable === undefined ||
-    existing?.durable === undefined ||
-    input.durable.version >= existing.durable.version
-  ) {
+  if (input.sync === undefined || existing?.sync === undefined || input.sync.version >= existing.sync.version) {
     registry.set(input.type, definition)
   }
-  if (input.durable) durableRegistry.set(versionedType(input.type, input.durable.version), definition)
+  if (input.sync)
+    syncRegistry.set(
+      versionedType(input.type, input.sync.version),
+      Object.assign(definition, {
+        encode: Schema.encodeUnknownSync(syncCodec(definition)),
+        decode: Schema.decodeUnknownSync(syncCodec(definition)),
+      }) as SyncDefinition,
+    )
   return definition as Schema.Schema<Payload<Definition<Type, Schema.Struct<Fields>>>> &
     Definition<Type, Schema.Struct<Fields>>
 }
@@ -113,7 +140,7 @@ export interface PublishOptions {
   readonly id?: ID
   readonly metadata?: Record<string, unknown>
   readonly location?: Location.Ref
-  /** Local operational projection committed atomically with a new durable event. Not replayed or serialized. */
+  /** Local operational projection committed atomically with a new synchronized event. Not replayed or serialized. */
   readonly commit?: (seq: number) => Effect.Effect<void>
 }
 
@@ -125,10 +152,14 @@ export interface Interface {
   ) => Effect.Effect<Payload<D>>
   readonly subscribe: <D extends Definition>(definition: D) => Stream.Stream<Payload<D>>
   readonly all: () => Stream.Stream<Payload>
-  readonly durable: (input: { readonly aggregateID: string; readonly after?: number }) => Stream.Stream<Payload>
-  /** @deprecated Use `all()` and consume the returned stream. */
-  readonly listen: (listener: Subscriber) => Effect.Effect<Unsubscribe>
-  readonly project: <D extends Definition>(definition: D, projector: Subscriber<D>) => Effect.Effect<void>
+  readonly aggregateEvents: (input: {
+    readonly aggregateID: string
+    readonly after?: Cursor
+  }) => Stream.Stream<CursorEvent>
+  readonly sync: (handler: Sync) => Effect.Effect<Unsubscribe>
+  readonly listen: (listener: Listener) => Effect.Effect<Unsubscribe>
+  readonly beforeCommit: (guard: CommitGuard) => Effect.Effect<void>
+  readonly project: <D extends Definition>(definition: D, projector: Projector<D>) => Effect.Effect<void>
   readonly replay: (
     event: SerializedEvent,
     options?: { readonly publish?: boolean; readonly ownerID?: string; readonly strictOwner?: boolean },
@@ -151,37 +182,37 @@ export const layerWith = (options?: LayerOptions) =>
   Layer.effect(
     Service,
     Effect.gen(function* () {
-      const pubsub = {
-        all: yield* PubSub.unbounded<Payload>(),
-        durable: new Map<string, Set<PubSub.PubSub<void>>>(),
-        typed: new Map<string, PubSub.PubSub<Payload>>(),
-      }
-      const projectors = new Map<string, Subscriber[]>()
-      const listeners = new Array<Subscriber>()
+      const all = yield* PubSub.unbounded<Payload>()
+      const synchronized = new Map<string, Set<PubSub.PubSub<void>>>()
+      const typed = new Map<string, PubSub.PubSub<Payload>>()
+      const projectors = new Map<string, AnyProjector[]>()
+      const commitGuards = new Array<CommitGuard>()
+      const listeners = new Array<Listener>()
+      const syncHandlers = new Array<Sync>()
       const { db } = yield* Database.Service
 
       const getOrCreate = (definition: Definition) =>
         Effect.gen(function* () {
-          const existing = pubsub.typed.get(definition.type)
+          const existing = typed.get(definition.type)
           if (existing) return existing
-          const created = yield* PubSub.unbounded<Payload>()
-          pubsub.typed.set(definition.type, created)
-          return created
+          const pubsub = yield* PubSub.unbounded<Payload>()
+          typed.set(definition.type, pubsub)
+          return pubsub
         })
 
       yield* Effect.addFinalizer(() =>
         Effect.gen(function* () {
-          yield* PubSub.shutdown(pubsub.all)
+          yield* PubSub.shutdown(all)
           yield* Effect.forEach(
-            pubsub.durable.values(),
+            synchronized.values(),
             (pubsubs) => Effect.forEach(pubsubs, PubSub.shutdown, { discard: true }),
             { discard: true },
           )
-          yield* Effect.forEach(pubsub.typed.values(), PubSub.shutdown, { discard: true })
+          yield* Effect.forEach(typed.values(), PubSub.shutdown, { discard: true })
         }),
       )
 
-      function commitDurableEvent(
+      function commitSyncEvent(
         event: Payload,
         input?: {
           readonly seq: number
@@ -193,20 +224,28 @@ export const layerWith = (options?: LayerOptions) =>
       ) {
         return Effect.gen(function* () {
           const definition = registry.get(event.type)
-          const durable = definition?.durable
-          if (durable) {
-            const aggregateID = (event.data as Record<string, unknown>)[durable.aggregate]
+          const sync = definition?.sync
+          if (sync) {
+            if (event.version !== sync.version) {
+              yield* Effect.die(
+                new InvalidSyncEventError({
+                  type: event.type,
+                  message: `Expected event version ${sync.version}, got ${event.version}`,
+                }),
+              )
+            }
+            const aggregateID = (event.data as Record<string, unknown>)[sync.aggregate]
             if (typeof aggregateID !== "string") {
               yield* Effect.die(
-                new InvalidDurableEventError({
+                new InvalidSyncEventError({
                   type: event.type,
-                  message: `Expected string aggregate field ${durable.aggregate}`,
+                  message: `Expected string aggregate field ${sync.aggregate}`,
                 }),
               )
             } else {
               if (input && input.aggregateID !== aggregateID) {
                 yield* Effect.die(
-                  new InvalidDurableEventError({
+                  new InvalidSyncEventError({
                     type: event.type,
                     message: `Aggregate mismatch: expected ${input.aggregateID}, got ${aggregateID}`,
                   }),
@@ -226,12 +265,12 @@ export const layerWith = (options?: LayerOptions) =>
                             .get()
                             .pipe(Effect.orDie)
                           const latest = row?.seq ?? -1
-                          const encoded = Schema.encodeUnknownSync(
-                            definition.data as Schema.Codec<unknown, unknown, never, never>,
-                          )(event.data) as Record<string, unknown>
+                          const encoded = syncRegistry
+                            .get(versionedType(definition.type, sync.version))!
+                            .encode(event.data) as Record<string, unknown>
                           if (input?.strictOwner && row?.ownerID && row.ownerID !== input.ownerID) {
                             yield* Effect.die(
-                              new InvalidDurableEventError({
+                              new InvalidSyncEventError({
                                 type: event.type,
                                 message: `Replay owner mismatch for aggregate ${aggregateID}: expected ${row.ownerID}, got ${input.ownerID ?? "none"}`,
                               }),
@@ -246,7 +285,7 @@ export const layerWith = (options?: LayerOptions) =>
                               .pipe(Effect.orDie)
                             if (
                               stored?.id === event.id &&
-                              stored.type === versionedType(definition.type, durable.version) &&
+                              stored.type === versionedType(definition.type, sync.version) &&
                               isDeepStrictEqual(stored.data, encoded)
                             ) {
                               if (input.ownerID && row?.ownerID == null) {
@@ -260,7 +299,7 @@ export const layerWith = (options?: LayerOptions) =>
                               return
                             }
                             yield* Effect.die(
-                              new InvalidDurableEventError({
+                              new InvalidSyncEventError({
                                 type: event.type,
                                 message: `Replay diverged at aggregate ${aggregateID} sequence ${input.seq}`,
                               }),
@@ -272,7 +311,7 @@ export const layerWith = (options?: LayerOptions) =>
                           const seq = input?.seq ?? latest + 1
                           if (input && seq !== latest + 1) {
                             yield* Effect.die(
-                              new InvalidDurableEventError({
+                              new InvalidSyncEventError({
                                 type: event.type,
                                 message: `Sequence mismatch for aggregate ${aggregateID}: expected ${latest + 1}, got ${seq}`,
                               }),
@@ -286,17 +325,16 @@ export const layerWith = (options?: LayerOptions) =>
                             .pipe(Effect.orDie)
                           if (stored)
                             yield* Effect.die(
-                              new InvalidDurableEventError({
+                              new InvalidSyncEventError({
                                 type: event.type,
                                 message: `Event ${event.id} already exists at aggregate ${stored.aggregateID} sequence ${stored.seq}`,
                               }),
                             )
-                          const committed = {
-                            ...event,
-                            durable: { aggregateID, seq, version: durable.version },
-                          } as Payload
+                          for (const guard of commitGuards) {
+                            yield* guard(event)
+                          }
                           for (const projector of list) {
-                            yield* projector(committed)
+                            yield* projector({ ...event, seq } as Payload)
                           }
                           if (commit) yield* commit(seq)
                           yield* db
@@ -318,7 +356,7 @@ export const layerWith = (options?: LayerOptions) =>
                                 id: event.id,
                                 aggregate_id: aggregateID,
                                 seq,
-                                type: versionedType(definition.type, durable.version),
+                                type: versionedType(definition.type, sync.version),
                                 data: encoded,
                               },
                             ])
@@ -331,8 +369,8 @@ export const layerWith = (options?: LayerOptions) =>
                     .pipe(Effect.orDie)
                   if (committed) {
                     yield* Effect.forEach(
-                      pubsub.durable.get(committed.aggregateID) ?? [],
-                      (wake) => PubSub.publish(wake, undefined),
+                      synchronized.get(committed.aggregateID) ?? [],
+                      (pubsub) => PubSub.publish(pubsub, undefined),
                       { discard: true },
                     )
                   }
@@ -346,25 +384,19 @@ export const layerWith = (options?: LayerOptions) =>
 
       function publishEvent<D extends Definition>(event: Payload<D>, commit?: PublishOptions["commit"]) {
         return Effect.gen(function* () {
-          const definition = registry.get(event.type)
-          if (!definition?.durable && commit)
+          const durable = registry.get(event.type)?.sync !== undefined
+          if (!durable && commit)
             return yield* Effect.die(
-              new InvalidDurableEventError({
+              new InvalidSyncEventError({
                 type: event.type,
-                message: "Local commit hooks require a durable event",
+                message: "Local commit hooks require a synchronized event",
               }),
             )
-          if (definition?.durable) {
-            const committed = yield* commitDurableEvent(event as Payload, undefined, commit)
+          if (durable) {
+            const committed = yield* commitSyncEvent(event as Payload, undefined, commit)
             if (committed) {
-              event = {
-                ...event,
-                durable: {
-                  aggregateID: committed.aggregateID,
-                  seq: committed.seq,
-                  version: definition.durable.version,
-                },
-              }
+              event = { ...event, seq: committed.seq }
+              yield* Effect.forEach(syncHandlers, (sync) => observe(event as Payload, "sync", sync), { discard: true })
               yield* notify(event as Payload, true)
               return event
             }
@@ -374,11 +406,12 @@ export const layerWith = (options?: LayerOptions) =>
         })
       }
 
-      const observe = (event: Payload, observer: (event: Payload) => Effect.Effect<void>) =>
+      const observe = (event: Payload, kind: "sync" | "listener", observer: (event: Payload) => Effect.Effect<void>) =>
         Effect.suspend(() => observer(event)).pipe(
           Effect.catchCauseIf(
             (cause) => !Cause.hasInterrupts(cause),
-            (cause) => Effect.logError("Event listener failed", { eventID: event.id, eventType: event.type, cause }),
+            (cause) =>
+              Effect.logError("Event observer failed", { eventID: event.id, eventType: event.type, kind, cause }),
           ),
         )
 
@@ -386,12 +419,12 @@ export const layerWith = (options?: LayerOptions) =>
         return Effect.gen(function* () {
           yield* Effect.forEach(
             listeners,
-            (listener) => (isolateListeners ? observe(event, listener) : listener(event)),
+            (listener) => (isolateListeners ? observe(event, "listener", listener) : listener(event)),
             { discard: true },
           )
-          const typed = pubsub.typed.get(event.type)
-          if (typed) yield* PubSub.publish(typed, event)
-          yield* PubSub.publish(pubsub.all, event)
+          const pubsub = typed.get(event.type)
+          if (pubsub) yield* PubSub.publish(pubsub, event)
+          yield* PubSub.publish(all, event)
         })
       }
 
@@ -408,6 +441,7 @@ export const layerWith = (options?: LayerOptions) =>
               id: options?.id ?? ID.create(),
               ...(options?.metadata ? { metadata: options.metadata } : {}),
               type: definition.type,
+              ...(definition.sync === undefined ? {} : { version: definition.sync.version }),
               ...(location ? { location } : {}),
               data,
             } as Payload<D>,
@@ -421,37 +455,27 @@ export const layerWith = (options?: LayerOptions) =>
         options?: { readonly publish?: boolean; readonly ownerID?: string; readonly strictOwner?: boolean },
       ) {
         return Effect.gen(function* () {
-          const definition = durableRegistry.get(event.type)
-          if (!definition?.durable) {
+          const definition = syncRegistry.get(event.type)
+          if (!definition) {
             yield* Effect.die(
-              new InvalidDurableEventError({ type: event.type, message: `Unknown durable event type ${event.type}` }),
+              new InvalidSyncEventError({ type: event.type, message: `Unknown sync event type ${event.type}` }),
             )
           } else {
             const payload = {
               id: event.id,
               type: definition.type,
-              data: Schema.decodeUnknownSync(definition.data as Schema.Codec<unknown, unknown, never, never>)(
-                event.data,
-              ),
+              version: definition.sync.version,
+              data: definition.decode(event.data),
+              replay: true,
             } as Payload
-            const committed = yield* commitDurableEvent(payload, {
+            const committed = yield* commitSyncEvent(payload, {
               seq: event.seq,
               aggregateID: event.aggregateID,
               ownerID: options?.ownerID,
               strictOwner: options?.strictOwner,
             })
             if (committed && options?.publish) {
-              yield* notify(
-                {
-                  ...payload,
-                  durable: {
-                    aggregateID: committed.aggregateID,
-                    seq: committed.seq,
-                    version: definition.durable.version,
-                  },
-                },
-                true,
-              )
+              yield* notify({ ...payload, seq: committed.seq }, true)
             }
           }
         })
@@ -466,7 +490,7 @@ export const layerWith = (options?: LayerOptions) =>
           if (!source) return undefined
           if (events.some((event) => event.aggregateID !== source)) {
             yield* Effect.die(
-              new InvalidDurableEventError({
+              new InvalidSyncEventError({
                 type: events[0]?.type ?? "unknown",
                 message: "Replay events must belong to the same aggregate",
               }),
@@ -477,7 +501,7 @@ export const layerWith = (options?: LayerOptions) =>
             const seq = start + index
             if (event.seq !== seq) {
               yield* Effect.die(
-                new InvalidDurableEventError({
+                new InvalidSyncEventError({
                   type: event.type,
                   message: `Replay sequence mismatch at index ${index}: expected ${seq}, got ${event.seq}`,
                 }),
@@ -516,18 +540,22 @@ export const layerWith = (options?: LayerOptions) =>
           Stream.map((event) => event as Payload<D>),
         )
 
-      const streamAll = (): Stream.Stream<Payload> => Stream.fromPubSub(pubsub.all)
+      const streamAll = (): Stream.Stream<Payload> => Stream.fromPubSub(all)
 
-      const decodeSerializedEvent = (event: SerializedEvent): Payload => {
-        const definition = durableRegistry.get(event.type)
-        if (!definition?.durable) {
-          throw new InvalidDurableEventError({ type: event.type, message: `Unknown durable event type ${event.type}` })
+      const decodeSerializedEvent = (event: SerializedEvent): CursorEvent => {
+        const definition = syncRegistry.get(event.type)
+        if (!definition) {
+          throw new InvalidSyncEventError({ type: event.type, message: `Unknown sync event type ${event.type}` })
         }
         return {
-          id: event.id,
-          type: definition.type,
-          durable: { aggregateID: event.aggregateID, seq: event.seq, version: definition.durable.version },
-          data: Schema.decodeUnknownSync(definition.data as Schema.Codec<unknown, unknown, never, never>)(event.data),
+          cursor: Cursor.make(event.seq),
+          event: {
+            id: event.id,
+            type: definition.type,
+            version: definition.sync.version,
+            seq: event.seq,
+            data: definition.decode(event.data),
+          },
         }
       }
 
@@ -555,40 +583,43 @@ export const layerWith = (options?: LayerOptions) =>
           ),
         )
 
-      const subscribeDurable = (aggregateID: string) =>
+      const subscribeSynchronized = (aggregateID: string) =>
         Effect.gen(function* () {
-          const wake = yield* PubSub.sliding<void>(1)
-          const subscription = yield* PubSub.subscribe(wake)
+          const pubsub = yield* PubSub.sliding<void>(1)
+          const subscription = yield* PubSub.subscribe(pubsub)
           yield* Effect.acquireRelease(
             Effect.sync(() => {
-              const wakes = pubsub.durable.get(aggregateID) ?? new Set()
-              wakes.add(wake)
-              pubsub.durable.set(aggregateID, wakes)
+              const pubsubs = synchronized.get(aggregateID) ?? new Set()
+              pubsubs.add(pubsub)
+              synchronized.set(aggregateID, pubsubs)
             }),
             () =>
               Effect.sync(() => {
-                const wakes = pubsub.durable.get(aggregateID)
-                wakes?.delete(wake)
-                if (wakes?.size === 0) pubsub.durable.delete(aggregateID)
-              }).pipe(Effect.andThen(PubSub.shutdown(wake))),
+                const pubsubs = synchronized.get(aggregateID)
+                pubsubs?.delete(pubsub)
+                if (pubsubs?.size === 0) synchronized.delete(aggregateID)
+              }).pipe(Effect.andThen(PubSub.shutdown(pubsub))),
           )
           return subscription
         })
 
-      const durable = (input: { readonly aggregateID: string; readonly after?: number }): Stream.Stream<Payload> =>
+      const streamEvents = (input: {
+        readonly aggregateID: string
+        readonly after?: Cursor
+      }): Stream.Stream<CursorEvent> =>
         Stream.unwrap(
           Effect.gen(function* () {
-            const wakes = yield* subscribeDurable(input.aggregateID)
-            let sequence = input.after ?? -1
-            const read = Effect.suspend(() => readAfter(input.aggregateID, sequence)).pipe(
+            const synchronized = yield* subscribeSynchronized(input.aggregateID)
+            let cursor = input.after ?? -1
+            const read = Effect.suspend(() => readAfter(input.aggregateID, cursor)).pipe(
               Effect.tap((events) =>
                 Effect.sync(() => {
-                  sequence = events.at(-1)?.durable?.seq ?? sequence
+                  cursor = events.at(-1)?.cursor ?? cursor
                 }),
               ),
             )
             const historical = yield* read
-            const live = Stream.fromSubscription(wakes).pipe(
+            const live = Stream.fromSubscription(synchronized).pipe(
               Stream.mapEffect(() => read),
               Stream.flattenIterable,
             )
@@ -596,7 +627,7 @@ export const layerWith = (options?: LayerOptions) =>
           }),
         )
 
-      const listen = (listener: Subscriber): Effect.Effect<Unsubscribe> =>
+      const listen = (listener: Listener): Effect.Effect<Unsubscribe> =>
         Effect.sync(() => {
           listeners.push(listener)
           return Effect.sync(() => {
@@ -605,7 +636,21 @@ export const layerWith = (options?: LayerOptions) =>
           })
         })
 
-      const project = <D extends Definition>(definition: D, projector: Subscriber<D>): Effect.Effect<void> =>
+      const sync = (handler: Sync): Effect.Effect<Unsubscribe> =>
+        Effect.sync(() => {
+          syncHandlers.push(handler)
+          return Effect.sync(() => {
+            const index = syncHandlers.indexOf(handler)
+            if (index >= 0) syncHandlers.splice(index, 1)
+          })
+        })
+
+      const beforeCommit = (guard: CommitGuard): Effect.Effect<void> =>
+        Effect.sync(() => {
+          commitGuards.push(guard)
+        })
+
+      const project = <D extends Definition>(definition: D, projector: Projector<D>): Effect.Effect<void> =>
         Effect.sync(() => {
           const list = projectors.get(definition.type) ?? []
           list.push((event) => projector(event as Payload<D>))
@@ -616,8 +661,10 @@ export const layerWith = (options?: LayerOptions) =>
         publish,
         subscribe,
         all: streamAll,
-        durable,
+        aggregateEvents: streamEvents,
+        sync,
         listen,
+        beforeCommit,
         project,
         replay,
         replayAll,

packages/core/src/filesystem.ts

@@ -123,6 +123,6 @@ const baseLayer = Layer.effect(
   }),
 )
 
-export const layer = baseLayer.pipe(Layer.provide(FileSystemSearch.locationLayer), Layer.provide(FSUtil.defaultLayer))
+export const layer = baseLayer.pipe(Layer.provide(FileSystemSearch.defaultLayer), Layer.provide(FSUtil.defaultLayer))
 
 export const locationLayer = layer

packages/core/src/filesystem/search.ts

@@ -232,6 +232,6 @@ export const fffLayer = Layer.effect(
   }),
 )
 
-export const locationLayer = Layer.unwrap(
+export const defaultLayer = Layer.unwrap(
   Effect.sync(() => (Flag.OPENCODE_DISABLE_FFF || !Fff.available() ? ripgrepLayer : fffLayer)),
 )

packages/core/src/integration.ts

@@ -1,19 +1,7 @@
 export * as Integration from "./integration"
 
-import {
-  Cause,
-  Clock,
-  Context,
-  Duration,
-  Effect,
-  Exit,
-  Layer,
-  Schedule,
-  Schema,
-  Scope,
-  SynchronizedRef,
-  Types,
-} from "effect"
+import { Cause, Clock, Context, Duration, Effect, Exit, Layer, Schedule, Schema, Scope, SynchronizedRef } from "effect"
+import { castDraft, enableMapSet, type Draft } from "immer"
 import { Credential } from "./credential"
 import { IntegrationSchema } from "./integration/schema"
 import { withStatics } from "./schema"
@@ -54,14 +42,12 @@ export const SelectPrompt = Schema.Struct({
   type: Schema.Literal("select"),
   key: Schema.String,
   message: Schema.String,
-  options: Schema.mutable(
-    Schema.Array(
-      Schema.Struct({
-        label: Schema.String,
-        value: Schema.String,
-        hint: Schema.optional(Schema.String),
-      }),
-    ),
+  options: Schema.Array(
+    Schema.Struct({
+      label: Schema.String,
+      value: Schema.String,
+      hint: Schema.optional(Schema.String),
+    }),
   ),
   when: Schema.optional(When),
 }).annotate({ identifier: "Integration.SelectPrompt" })
@@ -74,7 +60,7 @@ export const OAuthMethod = Schema.Struct({
   id: MethodID,
   type: Schema.Literal("oauth"),
   label: Schema.String,
-  prompts: Schema.optional(Schema.mutable(Schema.Array(Prompt))),
+  prompts: Schema.optional(Schema.Array(Prompt)),
 }).annotate({ identifier: "Integration.OAuthMethod" })
 export type OAuthMethod = typeof OAuthMethod.Type
 
@@ -86,7 +72,7 @@ export type KeyMethod = typeof KeyMethod.Type
 
 export const EnvMethod = Schema.Struct({
   type: Schema.Literal("env"),
-  names: Schema.mutable(Schema.Array(Schema.String)),
+  names: Schema.Array(Schema.String),
 }).annotate({ identifier: "Integration.EnvMethod" })
 export type EnvMethod = typeof EnvMethod.Type
 
@@ -96,8 +82,8 @@ export type Method = typeof Method.Type
 export class Info extends Schema.Class<Info>("Integration.Info")({
   id: ID,
   name: Schema.String,
-  methods: Schema.mutable(Schema.Array(Method)),
-  connections: Schema.mutable(Schema.Array(IntegrationConnection.Info)),
+  methods: Schema.Array(Method),
+  connections: Schema.Array(IntegrationConnection.Info),
 }) {}
 
 export type Inputs = Readonly<{ [key: string]: string }>
@@ -108,11 +94,11 @@ export type OAuthAuthorization = {
 } & (
   | {
       readonly mode: "auto"
-      readonly callback: Effect.Effect<Credential.Value, unknown>
+      readonly callback: Effect.Effect<Credential.Info, unknown>
     }
   | {
       readonly mode: "code"
-      readonly callback: (code: string) => Effect.Effect<Credential.Value, unknown>
+      readonly callback: (code: string) => Effect.Effect<Credential.Info, unknown>
     }
 )
 
@@ -186,19 +172,19 @@ export type Ref = {
 }
 
 type Entry = {
-  ref: Types.DeepMutable<Ref>
-  methods: Types.DeepMutable<Method>[]
-  implementations: Map<MethodID, Types.DeepMutable<OAuthImplementation>>
+  ref: Ref
+  methods: Method[]
+  implementations: Map<MethodID, OAuthImplementation>
 }
 
 type Data = {
   integrations: Map<ID, Entry>
 }
 
-export type Draft = {
+export type Editor = {
   list: () => readonly Ref[]
   get: (id: ID) => Ref | undefined
-  update: (id: ID, update: (integration: Types.DeepMutable<Ref>) => void) => void
+  update: (id: ID, update: (integration: Draft<Ref>) => void) => void
   remove: (id: ID) => void
   method: {
     list: (integrationID: ID) => readonly Method[]
@@ -207,13 +193,18 @@ export type Draft = {
   }
 }
 
-export interface Interface extends State.Transformable<Draft> {
+export interface Interface {
   /** Registers a scoped transform over the integration registry. */
+  readonly transform: State.Interface<Data, Editor>["transform"]
+  /** Registers and immediately applies a scoped integration registry update. */
+  readonly update: State.Interface<Data, Editor>["update"]
   /** Returns one integration with its methods and current connections. */
   readonly get: (id: ID) => Effect.Effect<Info | undefined>
   /** Returns all integrations with their methods and current connections. */
   readonly list: () => Effect.Effect<Info[]>
   readonly connection: {
+    /** Returns active connections for every registered or credential-backed integration. */
+    readonly list: () => Effect.Effect<Map<ID, IntegrationConnection.Info>>
     /** Returns the active connection for one integration. */
     readonly forIntegration: (id: ID) => Effect.Effect<IntegrationConnection.Info | undefined>
     /** Runs a key method and stores the resulting credential. */
@@ -239,7 +230,7 @@ export interface Interface extends State.Transformable<Draft> {
     /** Updates a stored credential exposed as a connection. */
     readonly update: (
       credentialID: Credential.ID,
-      updates: Partial<Pick<Credential.Info, "label">>,
+      updates: Partial<Pick<Credential.Stored, "label">>,
     ) => Effect.Effect<void>
     /** Removes a stored credential connection. */
     readonly remove: (credentialID: Credential.ID) => Effect.Effect<void>
@@ -261,6 +252,8 @@ export interface Interface extends State.Transformable<Draft> {
 
 export class Service extends Context.Service<Service, Interface>()("@opencode/v2/Integration") {}
 
+enableMapSet()
+
 const attemptLifetime = Duration.toMillis(Duration.minutes(10))
 const terminalRetention = Duration.toMillis(Duration.minutes(1))
 const scrubInterval = Duration.seconds(30)
@@ -291,17 +284,15 @@ export const locationLayer = Layer.effect(
     const events = yield* EventV2.Service
     const scope = yield* Scope.Scope
     const attempts = SynchronizedRef.makeUnsafe(new Map<AttemptID, AttemptEntry>())
-    const state = State.create<Data, Draft>({
+    const state = State.create<Data, Editor>({
       initial: () => ({ integrations: new Map<ID, Entry>() }),
-      draft: (draft) => ({
+      editor: (draft) => ({
         list: () => Array.from(draft.integrations.values(), (entry) => entry.ref) as Ref[],
         get: (id) => draft.integrations.get(id)?.ref as Ref | undefined,
         update: (id, update) => {
-          const current = draft.integrations.get(id) ?? {
-            ref: { id, name: id },
-            methods: [],
-            implementations: new Map(),
-          }
+          const current =
+            draft.integrations.get(id) ??
+            castDraft({ ref: { id, name: id } as Ref, methods: [], implementations: new Map() })
           if (!draft.integrations.has(id)) draft.integrations.set(id, current)
           update(current.ref)
           current.ref.id = id
@@ -310,14 +301,16 @@ export const locationLayer = Layer.effect(
         method: {
           list: (integrationID) => (draft.integrations.get(integrationID)?.methods as Method[] | undefined) ?? [],
           update: (implementation) => {
-            const current = draft.integrations.get(implementation.integrationID) ?? {
-              ref: {
-                id: implementation.integrationID,
-                name: implementation.integrationID,
-              },
-              methods: [],
-              implementations: new Map<MethodID, Types.DeepMutable<OAuthImplementation>>(),
-            }
+            const current =
+              draft.integrations.get(implementation.integrationID) ??
+              castDraft({
+                ref: {
+                  id: implementation.integrationID,
+                  name: implementation.integrationID,
+                } as Ref,
+                methods: [],
+                implementations: new Map<MethodID, OAuthImplementation>(),
+              })
             if (!draft.integrations.has(implementation.integrationID)) {
               draft.integrations.set(implementation.integrationID, current)
             }
@@ -326,13 +319,10 @@ export const locationLayer = Layer.effect(
               if (method.type !== "oauth" || implementation.method.type !== "oauth") return true
               return method.id === implementation.method.id
             })
-            if (index === -1) current.methods.push(implementation.method as Types.DeepMutable<Method>)
-            else current.methods[index] = implementation.method as Types.DeepMutable<Method>
-            if (implementation.method.type === "oauth") {
-              current.implementations.set(
-                implementation.method.id,
-                implementation as Types.DeepMutable<OAuthImplementation>,
-              )
+            if (index === -1) current.methods.push(castDraft(implementation.method))
+            else current.methods[index] = castDraft(implementation.method)
+            if (isOAuthImplementation(implementation)) {
+              current.implementations.set(implementation.method.id, castDraft(implementation))
             }
           },
           remove: (integrationID, method) => {
@@ -351,27 +341,39 @@ export const locationLayer = Layer.effect(
       finalize: () => events.publish(Event.Updated, {}).pipe(Effect.asVoid),
     })
 
-    const resolveConnections = (entry: Entry | undefined, saved: readonly Credential.Info[]) => {
-      const credentials = saved
-        .map((credential) => ({
-          type: "credential" as const,
-          id: credential.id,
-          label: credential.label,
-        }))
-        .toReversed()
-      const env = (entry?.methods ?? [])
+    const connections = (entry: Entry, saved: readonly Credential.Stored[]): IntegrationConnection.Info[] => {
+      const connected = saved.map((credential) => ({
+        type: "credential" as const,
+        id: credential.id,
+        label: credential.label,
+      }))
+      const detected = entry.methods
         .filter((method) => method.type === "env")
         .flatMap((method) => method.names.filter((name) => process.env[name]))
         .map((name) => ({ type: "env" as const, name }))
-      return [...credentials, ...env]
+      return [...connected, ...detected]
     }
 
-    const project = (entry: Entry, connections: IntegrationConnection.Info[]) =>
+    const activeConnection = (
+      entry: Entry | undefined,
+      saved: readonly Credential.Stored[],
+    ): IntegrationConnection.Info | undefined => {
+      const credential = saved.at(-1)
+      if (credential) return { type: "credential", id: credential.id, label: credential.label }
+      if (!entry) return
+      const name = entry.methods
+        .filter((method) => method.type === "env")
+        .flatMap((method) => method.names)
+        .find((name) => process.env[name])
+      if (name) return { type: "env", name }
+    }
+
+    const project = (entry: Entry, saved: readonly Credential.Stored[]) =>
       new Info({
         id: entry.ref.id,
         name: entry.ref.name,
         methods: entry.methods,
-        connections,
+        connections: connections(entry, saved),
       })
 
     const authorize = <A, E, R>(effect: Effect.Effect<A, E, R>) =>
@@ -385,7 +387,7 @@ export const locationLayer = Layer.effect(
       return error instanceof Error ? error.message : String(error)
     }
 
-    const settle = Effect.fnUntraced(function* (attemptID: AttemptID, exit: Exit.Exit<Credential.Value, unknown>) {
+    const settle = Effect.fnUntraced(function* (attemptID: AttemptID, exit: Exit.Exit<Credential.Info, unknown>) {
       const now = yield* Clock.currentTimeMillis
       const result = yield* SynchronizedRef.modify(attempts, (current) => {
         const attempt = current.get(attemptID)
@@ -432,22 +434,32 @@ export const locationLayer = Layer.effect(
 
     return Service.of({
       transform: state.transform,
-      rebuild: state.rebuild,
+      update: state.update,
       get: Effect.fn("Integration.get")(function* (id) {
         const entry = state.get().integrations.get(id)
         if (!entry) return undefined
-        return project(entry, resolveConnections(entry, yield* credentials.list(id)))
+        return project(entry, yield* credentials.list(id))
       }),
       list: Effect.fn("Integration.list")(function* () {
-        const saved = Map.groupBy(yield* credentials.all(), (credential) => credential.integrationID)
-        return Array.from(state.get().integrations.values(), (entry) =>
-          project(entry, resolveConnections(entry, saved.get(entry.ref.id) ?? [])),
-        ).toSorted((a, b) => a.name.localeCompare(b.name))
+        return (yield* Effect.forEach(state.get().integrations.values(), (entry) =>
+          Effect.gen(function* () {
+            return project(entry, yield* credentials.list(entry.ref.id))
+          }),
+        )).toSorted((a, b) => a.name.localeCompare(b.name))
       }),
       connection: {
+        list: Effect.fn("Integration.connection.list")(function* () {
+          const saved = Map.groupBy(yield* credentials.all(), (credential) => credential.integrationID)
+          return new Map(
+            new Set([...state.get().integrations.keys(), ...saved.keys()]).values().flatMap((id) => {
+              const connection = activeConnection(state.get().integrations.get(id), saved.get(id) ?? [])
+              return connection ? [[id, connection] as const] : []
+            }),
+          )
+        }),
         forIntegration: Effect.fn("Integration.connection.forIntegration")(function* (id) {
           const entry = state.get().integrations.get(id)
-          return resolveConnections(entry, yield* credentials.list(id))[0]
+          return activeConnection(entry, yield* credentials.list(id))
         }),
         key: Effect.fn("Integration.connection.key")(function* (input) {
           const method = state

packages/core/src/model-request.ts

@@ -33,7 +33,7 @@ export type Request = typeof Request.Type
 interface MutableRequest {
   headers: Record<string, string>
   body: Record<string, unknown>
-  generation?: Record<string, unknown>
+  generation?: Generation
   options?: Record<string, unknown>
 }
 

packages/core/src/model.ts

@@ -1,4 +1,5 @@
-import { Schema, Types } from "effect"
+import { DateTime, Schema } from "effect"
+import { DateTimeUtcFromMillis } from "effect/Schema"
 import { ProviderV2 } from "./provider"
 import { ModelRequest } from "./model-request"
 
@@ -15,8 +16,8 @@ export type Family = typeof Family.Type
 export const Capabilities = Schema.Struct({
   tools: Schema.Boolean,
   // mime patterns, image, audio, video/*, text/*
-  input: Schema.String.pipe(Schema.Array, Schema.mutable),
-  output: Schema.String.pipe(Schema.Array, Schema.mutable),
+  input: Schema.String.pipe(Schema.Array),
+  output: Schema.String.pipe(Schema.Array),
 })
 export type Capabilities = typeof Capabilities.Type
 
@@ -66,11 +67,11 @@ export class Info extends Schema.Class<Info>("ModelV2.Info")({
   variants: Schema.Struct({
     id: VariantID,
     ...ModelRequest.Request.fields,
-  }).pipe(Schema.Array, Schema.mutable),
+  }).pipe(Schema.Array),
   time: Schema.Struct({
-    released: Schema.Finite,
+    released: DateTimeUtcFromMillis,
   }),
-  cost: Cost.pipe(Schema.Array, Schema.mutable),
+  cost: Cost.pipe(Schema.Array),
   status: Schema.Literals(["alpha", "beta", "deprecated", "active"]),
   enabled: Schema.Boolean,
   limit: Schema.Struct({
@@ -102,7 +103,7 @@ export class Info extends Schema.Class<Info>("ModelV2.Info")({
       },
       variants: [],
       time: {
-        released: 0,
+        released: DateTime.makeUnsafe(0),
       },
       cost: [],
       status: "active",
@@ -115,10 +116,6 @@ export class Info extends Schema.Class<Info>("ModelV2.Info")({
   }
 }
 
-export type MutableInfo = Omit<Types.DeepMutable<Info>, "api"> & {
-  api: ProviderV2.MutableApi<Api>
-}
-
 export function parse(input: string): { providerID: ProviderV2.ID; modelID: ID } {
   const [providerID, ...modelID] = input.split("/")
   return {

packages/core/src/npm.ts

@@ -20,7 +20,7 @@ export class InstallFailedError extends Schema.TaggedErrorClass<InstallFailedErr
 
 export interface EntryPoint {
   readonly directory: string
-  readonly entrypoint?: string
+  readonly entrypoint: Option.Option<string>
 }
 
 export interface Interface {
@@ -34,7 +34,7 @@ export interface Interface {
       }[]
     },
   ) => Effect.Effect<void, EffectFlock.LockError | InstallFailedError>
-  readonly which: (pkg: string, bin?: string) => Effect.Effect<string | undefined>
+  readonly which: (pkg: string, bin?: string) => Effect.Effect<Option.Option<string>>
 }
 
 export class Service extends Context.Service<Service, Interface>()("@opencode/Npm") {}
@@ -47,11 +47,12 @@ export function sanitize(pkg: string) {
 }
 
 const resolveEntryPoint = (name: string, dir: string): EntryPoint => {
-  let entrypoint: string | undefined
+  let entrypoint: Option.Option<string>
   try {
-    entrypoint = typeof Bun !== "undefined" ? import.meta.resolve(name, dir) : import.meta.resolve(dir)
+    const resolved = typeof Bun !== "undefined" ? import.meta.resolve(name, dir) : import.meta.resolve(dir)
+    entrypoint = Option.some(resolved)
   } catch {
-    entrypoint = undefined
+    entrypoint = Option.none()
   }
   return {
     directory: dir,
@@ -129,7 +130,7 @@ export const layer = Layer.effect(
       const first = tree.edgesOut.values().next().value?.to
       if (!first) {
         const result = resolveEntryPoint(name, path.join(dir, "node_modules", name))
-        if (result.entrypoint) return result
+        if (Option.isSome(result.entrypoint)) return result
         return yield* new InstallFailedError({ add: [pkg], dir })
       }
       return resolveEntryPoint(first.name, first.path)
@@ -218,24 +219,22 @@ export const layer = Layer.effect(
         return Option.some(files[0])
       })
 
-      return Option.getOrUndefined(
-        yield* Effect.gen(function* () {
-          const bin = yield* pick()
-          if (Option.isSome(bin)) {
-            return Option.some(path.join(binDir, bin.value))
-          }
+      return yield* Effect.gen(function* () {
+        const bin = yield* pick()
+        if (Option.isSome(bin)) {
+          return Option.some(path.join(binDir, bin.value))
+        }
 
-          yield* fs.remove(path.join(dir, "package-lock.json")).pipe(Effect.orElseSucceed(() => {}))
+        yield* fs.remove(path.join(dir, "package-lock.json")).pipe(Effect.orElseSucceed(() => {}))
 
-          yield* add(pkg)
+        yield* add(pkg)
 
-          const resolved = yield* pick()
-          if (Option.isNone(resolved)) return Option.none<string>()
-          return Option.some(path.join(binDir, resolved.value))
-        }).pipe(
-          Effect.scoped,
-          Effect.orElseSucceed(() => Option.none<string>()),
-        ),
+        const resolved = yield* pick()
+        if (Option.isNone(resolved)) return Option.none<string>()
+        return Option.some(path.join(binDir, resolved.value))
+      }).pipe(
+        Effect.scoped,
+        Effect.orElseSucceed(() => Option.none<string>()),
       )
     })
 
@@ -262,9 +261,14 @@ export async function install(...args: Parameters<Interface["install"]>) {
 }
 
 export async function add(...args: Parameters<Interface["add"]>) {
-  return runPromise((svc) => svc.add(...args))
+  const entry = await runPromise((svc) => svc.add(...args))
+  return {
+    directory: entry.directory,
+    entrypoint: Option.getOrUndefined(entry.entrypoint),
+  }
 }
 
 export async function which(...args: Parameters<Interface["which"]>) {
-  return runPromise((svc) => svc.which(...args))
+  const resolved = await runPromise((svc) => svc.which(...args))
+  return Option.getOrUndefined(resolved)
 }

packages/core/src/permission/schema.ts

@@ -12,5 +12,5 @@ export const Rule = Schema.Struct({
 }).annotate({ identifier: "PermissionV2.Rule" })
 export type Rule = typeof Rule.Type
 
-export const Ruleset = Schema.mutable(Schema.Array(Rule)).annotate({ identifier: "PermissionV2.Ruleset" })
+export const Ruleset = Schema.Array(Rule).annotate({ identifier: "PermissionV2.Ruleset" })
 export type Ruleset = typeof Ruleset.Type

packages/core/src/plugin.ts

@@ -7,7 +7,6 @@ import type { ModelV2 } from "./model"
 import type { Catalog } from "./catalog"
 import { EventV2 } from "./event"
 import { KeyedMutex } from "./effect/keyed-mutex"
-import { State } from "./state"
 
 export const ID = Schema.String.pipe(Schema.brand("Plugin.ID"))
 export type ID = typeof ID.Type
@@ -23,7 +22,7 @@ export const Event = {
 
 type HookSpec = {
   "catalog.transform": {
-    input: Catalog.Draft
+    input: Catalog.Editor
     output: {}
   }
   "aisdk.language": {
@@ -63,16 +62,18 @@ export type HookFunctions = {
 export type HookInput<Name extends keyof Hooks> = HookSpec[Name]["input"]
 export type HookOutput<Name extends keyof Hooks> = HookSpec[Name]["output"]
 
+export type Effect<R = never> = Effect.Effect<HookFunctions | void, never, R | Scope.Scope>
+
+export function define<R>(input: { id: ID; effect: Effect.Effect<HookFunctions | void, never, R> }) {
+  return input
+}
+
 export interface Interface {
   readonly add: (input: {
-    id: string
+    id: ID
     effect: Effect.Effect<void | HookFunctions, never, Scope.Scope>
   }) => Effect.Effect<void, never, never>
   readonly remove: (id: ID) => Effect.Effect<void>
-  readonly hook: <Name extends keyof Hooks>(
-    name: Name,
-    callback: (input: Hooks[Name]) => Effect.Effect<void> | void,
-  ) => Effect.Effect<State.Registration, never, Scope.Scope>
   readonly triggerFor: <Name extends keyof Hooks>(
     id: ID,
     name: Name,
@@ -96,48 +97,35 @@ export const layer = Layer.effect(
       hooks: HookFunctions
       scope: Scope.Closeable
     }[] = []
-    let registrations: {
-      [Name in keyof Hooks]: {
-        name: Name
-        callback: (input: Hooks[Name]) => Effect.Effect<void> | void
-      }
-    }[keyof Hooks][] = []
     const events = yield* EventV2.Service
+    const scope = yield* Scope.Scope
     const locks = KeyedMutex.makeUnsafe<ID>()
-    const scope = yield* Scope.make()
-
-    // One registry-owned scope lets shutdown remove every plugin transform in one batch.
-    yield* Effect.addFinalizer((exit) =>
-      Effect.gen(function* () {
-        hooks = []
-        yield* State.batch(Scope.close(scope, exit))
-      }),
-    )
 
     const svc = Service.of({
       add: Effect.fn("Plugin.add")(function* (input) {
-        const id = ID.make(input.id)
-        yield* locks.withLock(id)(
+        yield* locks.withLock(input.id)(
           Effect.gen(function* () {
-            const existing = hooks.find((item) => item.id === id)
-            if (existing) yield* State.batch(Scope.close(existing.scope, Exit.void)).pipe(Effect.ignore)
+            const existing = hooks.find((item) => item.id === input.id)
+            if (existing) yield* Scope.close(existing.scope, Exit.void).pipe(Effect.ignore)
             const childScope = yield* Scope.fork(scope)
             const result = yield* input.effect.pipe(
               Scope.provide(childScope),
               Effect.withSpan("Plugin.load", {
                 attributes: {
-                  "plugin.id": id,
+                  "plugin.id": input.id,
                 },
               }),
               Effect.onExit((exit) => (Exit.isFailure(exit) ? Scope.close(childScope, exit) : Effect.void)),
             )
-            const next = {
-              id,
-              hooks: result ?? {},
-              scope: childScope,
-            }
-            hooks = existing ? hooks.with(hooks.indexOf(existing), next) : [...hooks, next]
-            yield* events.publish(Event.Added, { id })
+            hooks = [
+              ...hooks.filter((item) => item.id !== input.id),
+              {
+                id: input.id,
+                hooks: result ?? {},
+                scope: childScope,
+              },
+            ]
+            yield* events.publish(Event.Added, { id: input.id })
           }),
         )
       }),
@@ -172,12 +160,6 @@ export const layer = Layer.effect(
           )
         }
 
-        for (const item of registrations) {
-          if (item.name !== name) continue
-          const result = item.callback(event as never)
-          if (Effect.isEffect(result)) yield* result
-        }
-
         for (const [field, draft] of draftEntries) {
           event[field] = finishDraft(draft)
         }
@@ -189,23 +171,10 @@ export const layer = Layer.effect(
           Effect.gen(function* () {
             const existing = hooks.find((item) => item.id === id)
             hooks = hooks.filter((item) => item.id !== id)
-            if (existing) yield* State.batch(Scope.close(existing.scope, Exit.void)).pipe(Effect.ignore)
+            if (existing) yield* Scope.close(existing.scope, Exit.void).pipe(Effect.ignore)
           }),
         )
       }),
-      hook: Effect.fn("Plugin.hook")(function* (name, callback) {
-        const scope = yield* Scope.Scope
-        const registration = { name, callback } as (typeof registrations)[number]
-        let active = true
-        registrations = [...registrations, registration]
-        const dispose = Effect.sync(() => {
-          if (!active) return
-          active = false
-          registrations = registrations.filter((item) => item !== registration)
-        })
-        yield* Scope.addFinalizer(scope, dispose)
-        return { dispose }
-      }),
     })
     return svc
   }),

packages/core/src/plugin/agent.ts

@@ -1,11 +1,12 @@
 export * as AgentPlugin from "./agent"
 
 import path from "path"
-import { define } from "@opencode-ai/plugin/v2/effect"
 import { Effect } from "effect"
 import { AgentV2 } from "../agent"
 import { Global } from "../global"
+import { Location } from "../location"
 import { PermissionV2 } from "../permission"
+import { PluginV2 } from "../plugin"
 
 const TRUNCATION_GLOB = path.join(Global.Path.data, "tool-output", "*")
 const BUILD_SYSTEM =
@@ -96,10 +97,12 @@ Rules:
 - If the conversation ends with an unanswered question to the user, preserve that exact question
 - If the conversation ends with an imperative statement or request to the user (e.g. "Now please run the command and paste the console output"), always include that exact request in the summary`
 
-export const Plugin = define({
-  id: "agent",
-  effect: Effect.fn(function* (ctx) {
-    const worktree = ctx.location.directory
+export const Plugin = PluginV2.define({
+  id: PluginV2.ID.make("agent"),
+  effect: Effect.gen(function* () {
+    const agent = yield* AgentV2.Service
+    const location = yield* Location.Service
+    const worktree = location.directory
     const whitelistedDirs = [TRUNCATION_GLOB, path.join(Global.Path.tmp, "*")]
     const readonlyExternalDirectory: PermissionV2.Ruleset = [
       { action: "external_directory", resource: "*", effect: "ask" },
@@ -119,8 +122,8 @@ export const Plugin = define({
       { action: "read", resource: "*.env.example", effect: "allow" },
     ]
 
-    yield* ctx.agent.transform((draft) => {
-      draft.update(AgentV2.defaultID, (item) => {
+    yield* agent.update((editor) => {
+      editor.update(AgentV2.defaultID, (item) => {
         item.description = "The default agent. Executes tools based on configured permissions."
         item.system ??= BUILD_SYSTEM
         item.mode = "primary"
@@ -132,7 +135,7 @@ export const Plugin = define({
         )
       })
 
-      draft.update(AgentV2.ID.make("plan"), (item) => {
+      editor.update(AgentV2.ID.make("plan"), (item) => {
         item.description = "Plan mode. Disallows all edit tools."
         item.mode = "primary"
         item.permissions.push(
@@ -151,14 +154,14 @@ export const Plugin = define({
         )
       })
 
-      draft.update(AgentV2.ID.make("general"), (item) => {
+      editor.update(AgentV2.ID.make("general"), (item) => {
         item.description =
           "General-purpose agent for researching complex questions and executing multi-step tasks. Use this agent to execute multiple units of work in parallel."
         item.mode = "subagent"
         item.permissions.push(...PermissionV2.merge(defaults, [{ action: "todowrite", resource: "*", effect: "deny" }]))
       })
 
-      draft.update(AgentV2.ID.make("explore"), (item) => {
+      editor.update(AgentV2.ID.make("explore"), (item) => {
         item.description =
           'Fast agent specialized for exploring codebases. Use this when you need to quickly find files by patterns (eg. "src/components/**/*.tsx"), search code for keywords (eg. "API endpoints"), or answer questions about the codebase (eg. "how do API endpoints work?"). When calling this agent, specify the desired thoroughness level: "quick" for basic searches, "medium" for moderate exploration, or "very thorough" for comprehensive analysis across multiple locations and naming conventions.'
         item.system = PROMPT_EXPLORE
@@ -179,21 +182,21 @@ export const Plugin = define({
         )
       })
 
-      draft.update(AgentV2.ID.make("compaction"), (item) => {
+      editor.update(AgentV2.ID.make("compaction"), (item) => {
         item.mode = "primary"
         item.hidden = true
         item.system = PROMPT_COMPACTION
         item.permissions.push(...PermissionV2.merge(defaults, [{ action: "*", resource: "*", effect: "deny" }]))
       })
 
-      draft.update(AgentV2.ID.make("title"), (item) => {
+      editor.update(AgentV2.ID.make("title"), (item) => {
         item.mode = "primary"
         item.hidden = true
         item.system = PROMPT_TITLE
         item.permissions.push(...PermissionV2.merge(defaults, [{ action: "*", resource: "*", effect: "deny" }]))
       })
 
-      draft.update(AgentV2.ID.make("summary"), (item) => {
+      editor.update(AgentV2.ID.make("summary"), (item) => {
         item.mode = "primary"
         item.hidden = true
         item.system = PROMPT_SUMMARY

packages/core/src/plugin/boot.ts

@@ -1,7 +1,7 @@
 export * as PluginBoot from "./boot"
 
-import type { Plugin as PublicPlugin } from "@opencode-ai/plugin/v2/effect"
 import { Context, Deferred, Effect, Layer } from "effect"
+import { Credential } from "../credential"
 import { Integration } from "../integration"
 import { AgentV2 } from "../agent"
 import { Catalog } from "../catalog"
@@ -13,7 +13,6 @@ import { ConfigSkillPlugin } from "../config/plugin/skill"
 import { ConfigReferencePlugin } from "../config/plugin/reference"
 import { EventV2 } from "../event"
 import { FSUtil } from "../fs-util"
-import { FileSystem } from "../filesystem"
 import { Global } from "../global"
 import { Location } from "../location"
 import { ModelsDev } from "../models-dev"
@@ -27,13 +26,29 @@ import { ModelsDevPlugin } from "./models-dev"
 import { ProviderPlugins } from "./provider"
 import { SkillV2 } from "../skill"
 import { Reference } from "../reference"
-import { State } from "../state"
-import { PluginHost } from "./host"
 
-type InternalPlugin = PublicPlugin<any>
+type Plugin = {
+  id: PluginV2.ID
+  effect: PluginV2.Effect<
+    | Catalog.Service
+    | CommandV2.Service
+    | Credential.Service
+    | Integration.Service
+    | AgentV2.Service
+    | Npm.Service
+    | EventV2.Service
+    | FSUtil.Service
+    | Global.Service
+    | Location.Service
+    | PluginV2.Service
+    | Config.Service
+    | ModelsDev.Service
+    | SkillV2.Service
+    | Reference.Service
+  >
+}
 
 export interface Interface {
-  readonly add: (plugin: PublicPlugin<any>) => Effect.Effect<void>
   readonly wait: () => Effect.Effect<void>
 }
 
@@ -45,7 +60,8 @@ export const layer = Layer.effect(
     const catalog = yield* Catalog.Service
     const commands = yield* CommandV2.Service
     const plugin = yield* PluginV2.Service
-    const integration = yield* Integration.Service
+    const credentials = yield* Credential.Service
+    const integrations = yield* Integration.Service
     const agents = yield* AgentV2.Service
     const config = yield* Config.Service
     const location = yield* Location.Service
@@ -53,54 +69,47 @@ export const layer = Layer.effect(
     const npm = yield* Npm.Service
     const events = yield* EventV2.Service
     const fs = yield* FSUtil.Service
-    const filesystem = yield* FileSystem.Service
     const global = yield* Global.Service
     const skill = yield* SkillV2.Service
-    const reference = yield* Reference.Service
-    const host = yield* PluginHost.make()
+    const references = yield* Reference.Service
     const done = yield* Deferred.make<void>()
 
-    const add = Effect.fn("PluginBoot.add")(function* (input: InternalPlugin) {
+    const add = Effect.fn("PluginBoot.add")(function* (input: Plugin) {
       yield* plugin.add({
         id: input.id,
-        effect: input
-          .effect(host)
-          .pipe(
-            Effect.provideService(Catalog.Service, catalog),
-            Effect.provideService(CommandV2.Service, commands),
-            Effect.provideService(Integration.Service, integration),
-            Effect.provideService(AgentV2.Service, agents),
-            Effect.provideService(Config.Service, config),
-            Effect.provideService(Location.Service, location),
-            Effect.provideService(ModelsDev.Service, modelsDev),
-            Effect.provideService(Npm.Service, npm),
-            Effect.provideService(EventV2.Service, events),
-            Effect.provideService(FSUtil.Service, fs),
-            Effect.provideService(FileSystem.Service, filesystem),
-            Effect.provideService(Global.Service, global),
-            Effect.provideService(SkillV2.Service, skill),
-            Effect.provideService(Reference.Service, reference),
-          ),
+        effect: input.effect.pipe(
+          Effect.provideService(Catalog.Service, catalog),
+          Effect.provideService(CommandV2.Service, commands),
+          Effect.provideService(Credential.Service, credentials),
+          Effect.provideService(Integration.Service, integrations),
+          Effect.provideService(AgentV2.Service, agents),
+          Effect.provideService(Config.Service, config),
+          Effect.provideService(Location.Service, location),
+          Effect.provideService(ModelsDev.Service, modelsDev),
+          Effect.provideService(Npm.Service, npm),
+          Effect.provideService(EventV2.Service, events),
+          Effect.provideService(FSUtil.Service, fs),
+          Effect.provideService(Global.Service, global),
+          Effect.provideService(SkillV2.Service, skill),
+          Effect.provideService(Reference.Service, references),
+          Effect.provideService(PluginV2.Service, plugin),
+        ),
       })
     })
 
     const boot = Effect.gen(function* () {
-      yield* State.batch(
-        Effect.gen(function* () {
-          yield* add(AgentPlugin.Plugin)
-          yield* add(CommandPlugin.Plugin)
-          yield* add(SkillPlugin.Plugin)
-          yield* add(ModelsDevPlugin)
-          yield* add(ConfigProviderPlugin.Plugin)
-          yield* add(ConfigAgentPlugin.Plugin)
-          yield* add(ConfigCommandPlugin.Plugin)
-          yield* add(ConfigSkillPlugin.Plugin)
-          yield* add(ConfigReferencePlugin.Plugin)
-          for (const item of ProviderPlugins) {
-            yield* add(item)
-          }
-        }),
-      )
+      yield* add(AgentPlugin.Plugin)
+      yield* add(CommandPlugin.Plugin)
+      yield* add(SkillPlugin.Plugin)
+      for (const item of ProviderPlugins) {
+        yield* add(item)
+      }
+      yield* add(ModelsDevPlugin)
+      yield* add(ConfigProviderPlugin.Plugin)
+      yield* add(ConfigAgentPlugin.Plugin)
+      yield* add(ConfigCommandPlugin.Plugin)
+      yield* add(ConfigSkillPlugin.Plugin)
+      yield* add(ConfigReferencePlugin.Plugin)
     }).pipe(Effect.withSpan("PluginBoot.boot"))
 
     yield* boot.pipe(
@@ -110,22 +119,12 @@ export const layer = Layer.effect(
     )
 
     return Service.of({
-      add: (input) =>
-        Deferred.await(done).pipe(
-          Effect.andThen(
-            plugin.add({
-              id: input.id,
-              effect: input.effect(host),
-            }),
-          ),
-        ),
       wait: () => Deferred.await(done),
     })
   }),
 )
 
 export const locationLayer = layer.pipe(
-  Layer.provideMerge(PluginV2.locationLayer),
   Layer.provideMerge(Integration.locationLayer),
   Layer.provideMerge(Catalog.locationLayer),
   Layer.provideMerge(CommandV2.locationLayer),
@@ -133,5 +132,4 @@ export const locationLayer = layer.pipe(
   Layer.provideMerge(AgentV2.locationLayer),
   Layer.provideMerge(SkillV2.locationLayer),
   Layer.provideMerge(Reference.locationLayer),
-  Layer.provideMerge(FileSystem.locationLayer),
 )

packages/core/src/plugin/command.ts

@@ -1,20 +1,26 @@
 export * as CommandPlugin from "./command"
 
-import { define } from "@opencode-ai/plugin/v2/effect"
 import { Effect } from "effect"
+import { CommandV2 } from "../command"
+import { Location } from "../location"
+import { PluginV2 } from "../plugin"
 import PROMPT_INITIALIZE from "./command/initialize.txt"
 import PROMPT_REVIEW from "./command/review.txt"
 
-export const Plugin = define({
-  id: "command",
-  effect: Effect.fn(function* (ctx) {
-    yield* ctx.command.transform((draft) => {
-      draft.update("init", (command) => {
-        command.template = PROMPT_INITIALIZE.replace("${path}", ctx.location.project.directory)
+export const Plugin = PluginV2.define({
+  id: PluginV2.ID.make("command"),
+  effect: Effect.gen(function* () {
+    const command = yield* CommandV2.Service
+    const location = yield* Location.Service
+    const transform = yield* command.transform()
+
+    yield* transform((editor) => {
+      editor.update("init", (command) => {
+        command.template = PROMPT_INITIALIZE.replace("${path}", location.project.directory)
         command.description = "guided AGENTS.md setup"
       })
-      draft.update("review", (command) => {
-        command.template = PROMPT_REVIEW.replace("${path}", ctx.location.project.directory)
+      editor.update("review", (command) => {
+        command.template = PROMPT_REVIEW.replace("${path}", location.project.directory)
         command.description = "review changes [commit|branch|pr], defaults to uncommitted"
         command.subtask = true
       })

packages/core/src/plugin/host.ts

@@ -1,236 +0,0 @@
-export * as PluginHost from "./host"
-
-import type { LanguageModelV3 } from "@ai-sdk/provider"
-import type { PluginHost as Interface } from "@opencode-ai/plugin/v2/effect"
-import type { Event as SDKEvent, ModelV2Info } from "@opencode-ai/sdk/v2/types"
-import { Effect, Schema, Stream } from "effect"
-import { AgentV2 } from "../agent"
-import { Catalog } from "../catalog"
-import { CommandV2 } from "../command"
-import { EventV2 } from "../event"
-import { FileSystem } from "../filesystem"
-import { Global } from "../global"
-import { Integration } from "../integration"
-import { Location } from "../location"
-import { ModelV2 } from "../model"
-import { Npm } from "../npm"
-import { PluginV2 } from "../plugin"
-import { ProviderV2 } from "../provider"
-import { Reference } from "../reference"
-import { SkillV2 } from "../skill"
-
-type EventMap = { [Item in SDKEvent as Item["type"]]: Item }
-type SDKHook = (event: {
-  readonly model: ModelV2Info
-  readonly package: string
-  readonly options: Record<string, any>
-  sdk?: any
-}) => Effect.Effect<void> | void
-type LanguageHook = (event: {
-  readonly model: ModelV2Info
-  readonly sdk: any
-  readonly options: Record<string, any>
-  language?: LanguageModelV3
-}) => Effect.Effect<void> | void
-
-export const make = Effect.fn("PluginHost.make")(function* () {
-  const agents = yield* AgentV2.Service
-  const catalog = yield* Catalog.Service
-  const commands = yield* CommandV2.Service
-  const events = yield* EventV2.Service
-  const filesystem = yield* FileSystem.Service
-  const global = yield* Global.Service
-  const integration = yield* Integration.Service
-  const location = yield* Location.Service
-  const npm = yield* Npm.Service
-  const plugin = yield* PluginV2.Service
-  const reference = yield* Reference.Service
-  const skill = yield* SkillV2.Service
-
-  return {
-    agent: {
-      get: (id) => agents.get(AgentV2.ID.make(id)),
-      default: agents.default,
-      list: agents.all,
-      rebuild: agents.rebuild,
-      transform: (callback) =>
-        agents.transform((draft) =>
-          callback({
-            list: draft.list,
-            get: (id) => draft.get(AgentV2.ID.make(id)),
-            default: (id) => draft.default(id === undefined ? undefined : AgentV2.ID.make(id)),
-            update: (id, update) => draft.update(AgentV2.ID.make(id), update),
-            remove: (id) => draft.remove(AgentV2.ID.make(id)),
-          }),
-        ),
-    },
-    aisdk: {
-      hook: (name, callback) => {
-        if (name === "sdk") {
-          const run = callback as SDKHook
-          return plugin.hook("aisdk.sdk", (event) => {
-            const output = {
-              model: event.model,
-              package: event.package,
-              options: event.options,
-              sdk: event.sdk,
-            }
-            const result = run(output)
-            return Effect.suspend(() => (Effect.isEffect(result) ? result : Effect.void)).pipe(
-              Effect.tap(() => Effect.sync(() => (event.sdk = output.sdk))),
-            )
-          })
-        }
-        const run = callback as LanguageHook
-        return plugin.hook("aisdk.language", (event) => {
-          const output = {
-            model: event.model,
-            sdk: event.sdk,
-            options: event.options,
-            language: event.language,
-          }
-          const result = run(output)
-          return Effect.suspend(() => (Effect.isEffect(result) ? result : Effect.void)).pipe(
-            Effect.tap(() => Effect.sync(() => (event.language = output.language))),
-          )
-        })
-      },
-    },
-    catalog: {
-      provider: {
-        get: (id) => catalog.provider.get(ProviderV2.ID.make(id)),
-        list: catalog.provider.all,
-        available: catalog.provider.available,
-      },
-      model: {
-        get: (providerID, modelID) => catalog.model.get(ProviderV2.ID.make(providerID), ModelV2.ID.make(modelID)),
-        list: catalog.model.all,
-        available: catalog.model.available,
-        default: catalog.model.default,
-        small: (providerID) => catalog.model.small(ProviderV2.ID.make(providerID)),
-      },
-      rebuild: catalog.rebuild,
-      transform: (callback) =>
-        catalog.transform((draft) =>
-          callback({
-            provider: {
-              list: draft.provider.list,
-              get: (id) => draft.provider.get(ProviderV2.ID.make(id)),
-              update: (id, update) => draft.provider.update(ProviderV2.ID.make(id), update),
-              remove: (id) => draft.provider.remove(ProviderV2.ID.make(id)),
-            },
-            model: {
-              get: (providerID, modelID) => draft.model.get(ProviderV2.ID.make(providerID), ModelV2.ID.make(modelID)),
-              update: (providerID, modelID, update) =>
-                draft.model.update(ProviderV2.ID.make(providerID), ModelV2.ID.make(modelID), update),
-              remove: (providerID, modelID) =>
-                draft.model.remove(ProviderV2.ID.make(providerID), ModelV2.ID.make(modelID)),
-              default: {
-                get: draft.model.default.get,
-                set: (providerID, modelID) =>
-                  draft.model.default.set(ProviderV2.ID.make(providerID), ModelV2.ID.make(modelID)),
-              },
-            },
-          }),
-        ),
-    },
-    command: {
-      get: commands.get,
-      list: commands.list,
-      rebuild: commands.rebuild,
-      transform: commands.transform,
-    },
-    event: {
-      subscribe: <Type extends keyof EventMap>(type: Type): Stream.Stream<EventMap[Type]> =>
-        Stream.unwrap(
-          Effect.sync(() => {
-            const definition = EventV2.registry.get(type)
-            if (!definition) throw new Error(`Unknown event type: ${type}`)
-            const encode = Schema.encodeUnknownSync(definition.data as Schema.Codec<unknown, unknown, never, never>)
-            return events.subscribe(definition).pipe(
-              Stream.map(
-                (event) =>
-                  ({
-                    id: event.id,
-                    type: event.type,
-                    properties: encode(event.data),
-                  }) as unknown as EventMap[Type],
-              ),
-            )
-          }),
-        ),
-    },
-    filesystem: {
-      read: (input) => filesystem.read(Schema.decodeUnknownSync(FileSystem.ReadInput)(input)),
-      list: (input) => filesystem.list(Schema.decodeUnknownSync(FileSystem.ListInput)(input ?? {})),
-      find: (input) => filesystem.find(Schema.decodeUnknownSync(FileSystem.FindInput)(input)),
-      glob: (input) => filesystem.glob(Schema.decodeUnknownSync(FileSystem.GlobInput)(input)),
-    },
-    integration: {
-      get: (id) => integration.get(Integration.ID.make(id)),
-      list: integration.list,
-      rebuild: integration.rebuild,
-      transform: (callback) =>
-        integration.transform((draft) =>
-          callback({
-            list: draft.list,
-            get: (id) => draft.get(Integration.ID.make(id)),
-            update: (id, update) => draft.update(Integration.ID.make(id), update),
-            remove: (id) => draft.remove(Integration.ID.make(id)),
-            method: {
-              list: (id) => draft.method.list(Integration.ID.make(id)),
-              update: (input) => {
-                if (input.method.type === "env") {
-                  draft.method.update({
-                    integrationID: Integration.ID.make(input.integrationID),
-                    method: { type: "env", names: input.method.names },
-                  })
-                  return
-                }
-                draft.method.update({
-                  integrationID: Integration.ID.make(input.integrationID),
-                  method: { type: "key", label: input.method.label },
-                })
-              },
-              remove: (id, method) =>
-                draft.method.remove(Integration.ID.make(id), Schema.decodeUnknownSync(Integration.Method)(method)),
-            },
-          }),
-        ),
-    },
-    location,
-    npm,
-    path: {
-      home: global.home,
-      data: global.data,
-      cache: global.cache,
-      config: global.config,
-      state: global.state,
-      temp: global.tmp,
-    },
-    reference: {
-      list: reference.list,
-      rebuild: reference.rebuild,
-      transform: (callback) =>
-        reference.transform((draft) =>
-          callback({
-            add: (name, source) => draft.add(name, Schema.decodeUnknownSync(Reference.Source)(source)),
-            remove: draft.remove,
-            list: draft.list,
-          }),
-        ),
-    },
-    skill: {
-      sources: skill.sources,
-      list: skill.list,
-      rebuild: skill.rebuild,
-      transform: (callback) =>
-        skill.transform((draft) =>
-          callback({
-            source: (source) => draft.source(Schema.decodeUnknownSync(SkillV2.Source)(source)),
-            list: draft.list,
-          }),
-        ),
-    },
-  } satisfies Interface
-})

packages/core/src/plugin/models-dev.ts

@@ -1,13 +1,16 @@
-import { define } from "@opencode-ai/plugin/v2/effect"
-import { Effect, Stream } from "effect"
+import { DateTime, Effect, Scope, Stream } from "effect"
+import { Catalog } from "../catalog"
+import { Integration } from "../integration"
+import { EventV2 } from "../event"
 import { ModelV2 } from "../model"
 import { ModelRequest } from "../model-request"
 import { ModelsDev } from "../models-dev"
+import { PluginV2 } from "../plugin"
 import { ProviderV2 } from "../provider"
 
 function released(date: string) {
   const time = Date.parse(date)
-  return Number.isFinite(time) ? time : 0
+  return DateTime.makeUnsafe(Number.isFinite(time) ? time : 0)
 }
 
 function cost(input: ModelsDev.Model["cost"]) {
@@ -48,16 +51,22 @@ function variants(model: ModelsDev.Model, packageName?: string) {
   })
 }
 
-export const ModelsDevPlugin = define({
-  id: "models-dev",
-  effect: Effect.fn(function* (ctx) {
+export const ModelsDevPlugin = PluginV2.define({
+  id: PluginV2.ID.make("models-dev"),
+  effect: Effect.gen(function* () {
+    const catalog = yield* Catalog.Service
+    const integrations = yield* Integration.Service
     const modelsDev = yield* ModelsDev.Service
-    yield* ctx.integration.transform(
-      Effect.fn(function* (integrations) {
-        const data = yield* modelsDev.get()
+    const events = yield* EventV2.Service
+    const scope = yield* Scope.Scope
+    const transform = yield* catalog.transform()
+    const integrationTransform = yield* integrations.transform()
+    const refresh = Effect.fn("ModelsDevPlugin.refresh")(function* () {
+      const data = yield* modelsDev.get()
+      yield* integrationTransform((integrations) => {
         for (const item of Object.values(data)) {
           if (item.env.length === 0) continue
-          const integrationID = item.id
+          const integrationID = Integration.ID.make(item.id)
           integrations.update(integrationID, (integration) => (integration.name = item.name))
           integrations.method.update({
             integrationID,
@@ -68,11 +77,8 @@ export const ModelsDevPlugin = define({
             method: { type: "env", names: [...item.env] },
           })
         }
-      }),
-    )
-    yield* ctx.catalog.transform(
-      Effect.fn(function* (catalog) {
-        const data = yield* modelsDev.get()
+      })
+      yield* transform((catalog) => {
         for (const item of Object.values(data)) {
           const providerID = ProviderV2.ID.make(item.id)
           catalog.provider.update(providerID, (provider) => {
@@ -126,10 +132,11 @@ export const ModelsDevPlugin = define({
             })
           }
         }
-      }),
-    )
-    yield* ctx.event.subscribe("models-dev.refreshed").pipe(
-      Stream.runForEach(() => ctx.integration.rebuild().pipe(Effect.andThen(ctx.catalog.rebuild()))),
+      })
+    })
+    yield* refresh()
+    yield* events.subscribe(ModelsDev.Event.Refreshed).pipe(
+      Stream.runForEach(() => refresh()),
       Effect.forkScoped({ startImmediately: true }),
     )
   }),

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

@@ -1,16 +1,15 @@
 import { Effect } from "effect"
-import { define } from "@opencode-ai/plugin/v2/effect"
+import { PluginV2 } from "../../plugin"
 
-export const AlibabaPlugin = define({
-  id: "alibaba",
-  effect: Effect.fn(function* (ctx) {
-    yield* ctx.aisdk.hook(
-      "sdk",
-      Effect.fn(function* (evt) {
+export const AlibabaPlugin = PluginV2.define({
+  id: PluginV2.ID.make("alibaba"),
+  effect: Effect.gen(function* () {
+    return {
+      "aisdk.sdk": Effect.fn(function* (evt) {
         if (evt.package !== "@ai-sdk/alibaba") return
         const mod = yield* Effect.promise(() => import("@ai-sdk/alibaba"))
         evt.sdk = mod.createAlibaba(evt.options)
       }),
-    )
+    }
   }),
 })

packages/core/src/plugin/provider/amazon-bedrock.ts

@@ -1,6 +1,6 @@
 import { Effect } from "effect"
 import type { LanguageModelV3 } from "@ai-sdk/provider"
-import { define } from "@opencode-ai/plugin/v2/effect"
+import { PluginV2 } from "../../plugin"
 import { ProviderV2 } from "../../provider"
 
 type MantleSDK = {
@@ -59,11 +59,11 @@ function selectMantleModel(sdk: MantleSDK, modelID: string) {
   return sdk.responses(modelID)
 }
 
-export const AmazonBedrockPlugin = define({
-  id: "amazon-bedrock",
-  effect: Effect.fn(function* (ctx) {
-    yield* ctx.catalog.transform(
-      Effect.fn(function* (evt) {
+export const AmazonBedrockPlugin = PluginV2.define({
+  id: PluginV2.ID.make("amazon-bedrock"),
+  effect: Effect.gen(function* () {
+    return {
+      "catalog.transform": Effect.fn(function* (evt) {
         for (const item of evt.provider.list()) {
           if (item.provider.api.type !== "aisdk") continue
           if (item.provider.api.package !== "@ai-sdk/amazon-bedrock") continue
@@ -77,10 +77,7 @@ export const AmazonBedrockPlugin = define({
           })
         }
       }),
-    )
-    yield* ctx.aisdk.hook(
-      "sdk",
-      Effect.fn(function* (evt) {
+      "aisdk.sdk": Effect.fn(function* (evt) {
         if (!["@ai-sdk/amazon-bedrock", "@ai-sdk/amazon-bedrock/mantle"].includes(evt.package)) return
         const options = { ...evt.options }
         const profile = typeof options.profile === "string" ? options.profile : process.env.AWS_PROFILE
@@ -111,10 +108,7 @@ export const AmazonBedrockPlugin = define({
         const mod = yield* Effect.promise(() => import("@ai-sdk/amazon-bedrock"))
         evt.sdk = mod.createAmazonBedrock(options)
       }),
-    )
-    yield* ctx.aisdk.hook(
-      "language",
-      Effect.fn(function* (evt) {
+      "aisdk.language": Effect.fn(function* (evt) {
         if (evt.model.providerID !== ProviderV2.ID.amazonBedrock) return
         if (evt.model.api.type === "aisdk" && evt.model.api.package === "@ai-sdk/amazon-bedrock/mantle") {
           evt.language = selectMantleModel(evt.sdk, evt.model.api.id)
@@ -123,6 +117,6 @@ export const AmazonBedrockPlugin = define({
         const region = typeof evt.options.region === "string" ? evt.options.region : process.env.AWS_REGION
         evt.language = evt.sdk.languageModel(resolveModelID(evt.model.api.id, region))
       }),
-    )
+    }
   }),
 })

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

@@ -1,11 +1,11 @@
 import { Effect } from "effect"
-import { define } from "@opencode-ai/plugin/v2/effect"
+import { PluginV2 } from "../../plugin"
 
-export const AnthropicPlugin = define({
-  id: "anthropic",
-  effect: Effect.fn(function* (ctx) {
-    yield* ctx.catalog.transform(
-      Effect.fn(function* (evt) {
+export const AnthropicPlugin = PluginV2.define({
+  id: PluginV2.ID.make("anthropic"),
+  effect: Effect.gen(function* () {
+    return {
+      "catalog.transform": Effect.fn(function* (evt) {
         for (const item of evt.provider.list()) {
           if (item.provider.api.type !== "aisdk") continue
           if (item.provider.api.package !== "@ai-sdk/anthropic") continue
@@ -15,14 +15,11 @@ export const AnthropicPlugin = define({
           })
         }
       }),
-    )
-    yield* ctx.aisdk.hook(
-      "sdk",
-      Effect.fn(function* (evt) {
+      "aisdk.sdk": Effect.fn(function* (evt) {
         if (evt.package !== "@ai-sdk/anthropic") return
         const mod = yield* Effect.promise(() => import("@ai-sdk/anthropic"))
         evt.sdk = mod.createAnthropic(evt.options)
       }),
-    )
+    }
   }),
 })

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

@@ -1,5 +1,5 @@
 import { Effect } from "effect"
-import { define } from "@opencode-ai/plugin/v2/effect"
+import { PluginV2 } from "../../plugin"
 import { ProviderV2 } from "../../provider"
 
 function selectLanguage(sdk: any, modelID: string, useChat: boolean) {
@@ -10,11 +10,11 @@ function selectLanguage(sdk: any, modelID: string, useChat: boolean) {
   return sdk.languageModel(modelID)
 }
 
-export const AzurePlugin = define({
-  id: "azure",
-  effect: Effect.fn(function* (ctx) {
-    yield* ctx.catalog.transform(
-      Effect.fn(function* (evt) {
+export const AzurePlugin = PluginV2.define({
+  id: PluginV2.ID.make("azure"),
+  effect: Effect.gen(function* () {
+    return {
+      "catalog.transform": Effect.fn(function* (evt) {
         for (const item of evt.provider.list()) {
           if (item.provider.api.type !== "aisdk") continue
           if (item.provider.api.package !== "@ai-sdk/azure") continue
@@ -27,10 +27,7 @@ export const AzurePlugin = define({
           })
         }
       }),
-    )
-    yield* ctx.aisdk.hook(
-      "sdk",
-      Effect.fn(function* (evt) {
+      "aisdk.sdk": Effect.fn(function* (evt) {
         if (evt.package !== "@ai-sdk/azure") return
         if (evt.model.providerID === ProviderV2.ID.azure) {
           if (
@@ -46,22 +43,19 @@ export const AzurePlugin = define({
         const mod = yield* Effect.promise(() => import("@ai-sdk/azure"))
         evt.sdk = mod.createAzure(evt.options)
       }),
-    )
-    yield* ctx.aisdk.hook(
-      "language",
-      Effect.fn(function* (evt) {
+      "aisdk.language": Effect.fn(function* (evt) {
         if (evt.model.providerID !== ProviderV2.ID.azure) return
         evt.language = selectLanguage(evt.sdk, evt.model.api.id, Boolean(evt.options.useCompletionUrls))
       }),
-    )
+    }
   }),
 })
 
-export const AzureCognitiveServicesPlugin = define({
-  id: "azure-cognitive-services",
-  effect: Effect.fn(function* (ctx) {
-    yield* ctx.catalog.transform(
-      Effect.fn(function* (evt) {
+export const AzureCognitiveServicesPlugin = PluginV2.define({
+  id: PluginV2.ID.make("azure-cognitive-services"),
+  effect: Effect.gen(function* () {
+    return {
+      "catalog.transform": Effect.fn(function* (evt) {
         const resourceName = process.env.AZURE_COGNITIVE_SERVICES_RESOURCE_NAME
         if (!resourceName) return
         for (const item of evt.provider.list()) {
@@ -73,13 +67,10 @@ export const AzureCognitiveServicesPlugin = define({
           })
         }
       }),
-    )
-    yield* ctx.aisdk.hook(
-      "language",
-      Effect.fn(function* (evt) {
+      "aisdk.language": Effect.fn(function* (evt) {
         if (evt.model.providerID !== ProviderV2.ID.make("azure-cognitive-services")) return
         evt.language = selectLanguage(evt.sdk, evt.model.api.id, Boolean(evt.options.useCompletionUrls))
       }),
-    )
+    }
   }),
 })

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

@@ -1,27 +1,24 @@
 import { Effect } from "effect"
-import { define } from "@opencode-ai/plugin/v2/effect"
+import { PluginV2 } from "../../plugin"
 
-export const CerebrasPlugin = define({
-  id: "cerebras",
-  effect: Effect.fn(function* (ctx) {
-    yield* ctx.catalog.transform(
-      Effect.fn(function* (evt) {
-        for (const item of evt.provider.list()) {
+export const CerebrasPlugin = PluginV2.define({
+  id: PluginV2.ID.make("cerebras"),
+  effect: Effect.gen(function* () {
+    return {
+      "catalog.transform": Effect.fn(function* (ctx) {
+        for (const item of ctx.provider.list()) {
           if (item.provider.api.type !== "aisdk") continue
           if (item.provider.api.package !== "@ai-sdk/cerebras") continue
-          evt.provider.update(item.provider.id, (provider) => {
+          ctx.provider.update(item.provider.id, (provider) => {
             provider.request.headers["X-Cerebras-3rd-Party-Integration"] = "opencode"
           })
         }
       }),
-    )
-    yield* ctx.aisdk.hook(
-      "sdk",
-      Effect.fn(function* (evt) {
+      "aisdk.sdk": Effect.fn(function* (evt) {
         if (evt.package !== "@ai-sdk/cerebras") return
         const mod = yield* Effect.promise(() => import("@ai-sdk/cerebras"))
         evt.sdk = mod.createCerebras(evt.options)
       }),
-    )
+    }
   }),
 })

packages/core/src/plugin/provider/cloudflare-ai-gateway.ts

@@ -1,14 +1,13 @@
 import os from "os"
 import { InstallationVersion } from "../../installation/version"
 import { Effect, Option, Schema } from "effect"
-import { define } from "@opencode-ai/plugin/v2/effect"
+import { PluginV2 } from "../../plugin"
 
-export const CloudflareAIGatewayPlugin = define({
-  id: "cloudflare-ai-gateway",
-  effect: Effect.fn(function* (ctx) {
-    yield* ctx.aisdk.hook(
-      "sdk",
-      Effect.fn(function* (evt) {
+export const CloudflareAIGatewayPlugin = PluginV2.define({
+  id: PluginV2.ID.make("cloudflare-ai-gateway"),
+  effect: Effect.gen(function* () {
+    return {
+      "aisdk.sdk": Effect.fn(function* (evt) {
         if (evt.package !== "ai-gateway-provider") return
         if (evt.options.baseURL) return
 
@@ -32,7 +31,7 @@ export const CloudflareAIGatewayPlugin = define({
           },
         }
       }),
-    )
+    }
   }),
 })
 

packages/core/src/plugin/provider/cloudflare-workers-ai.ts

@@ -1,16 +1,16 @@
 import os from "os"
 import { InstallationVersion } from "../../installation/version"
 import { Effect } from "effect"
-import { define } from "@opencode-ai/plugin/v2/effect"
+import { PluginV2 } from "../../plugin"
 import { ProviderV2 } from "../../provider"
 
 const providerID = ProviderV2.ID.make("cloudflare-workers-ai")
 
-export const CloudflareWorkersAIPlugin = define({
-  id: "cloudflare-workers-ai",
-  effect: Effect.fn(function* (ctx) {
-    yield* ctx.catalog.transform(
-      Effect.fn(function* (evt) {
+export const CloudflareWorkersAIPlugin = PluginV2.define({
+  id: PluginV2.ID.make("cloudflare-workers-ai"),
+  effect: Effect.gen(function* () {
+    return {
+      "catalog.transform": Effect.fn(function* (evt) {
         const item = evt.provider.get(providerID)
         if (!item) return
         evt.provider.update(item.provider.id, (provider) => {
@@ -20,10 +20,7 @@ export const CloudflareWorkersAIPlugin = define({
           if (accountId) provider.api.url = workersEndpoint(accountId)
         })
       }),
-    )
-    yield* ctx.aisdk.hook(
-      "sdk",
-      Effect.fn(function* (evt) {
+      "aisdk.sdk": Effect.fn(function* (evt) {
         if (evt.model.providerID !== providerID) return
         if (evt.package !== "@ai-sdk/openai-compatible") return
 
@@ -37,14 +34,11 @@ export const CloudflareWorkersAIPlugin = define({
           }) as any,
         )
       }),
-    )
-    yield* ctx.aisdk.hook(
-      "language",
-      Effect.fn(function* (evt) {
+      "aisdk.language": Effect.fn(function* (evt) {
         if (evt.model.providerID !== providerID) return
         evt.language = evt.sdk.languageModel(evt.model.api.id)
       }),
-    )
+    }
   }),
 })
 

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

@@ -1,16 +1,15 @@
 import { Effect } from "effect"
-import { define } from "@opencode-ai/plugin/v2/effect"
+import { PluginV2 } from "../../plugin"
 
-export const CoherePlugin = define({
-  id: "cohere",
-  effect: Effect.fn(function* (ctx) {
-    yield* ctx.aisdk.hook(
-      "sdk",
-      Effect.fn(function* (evt) {
+export const CoherePlugin = PluginV2.define({
+  id: PluginV2.ID.make("cohere"),
+  effect: Effect.gen(function* () {
+    return {
+      "aisdk.sdk": Effect.fn(function* (evt) {
         if (evt.package !== "@ai-sdk/cohere") return
         const mod = yield* Effect.promise(() => import("@ai-sdk/cohere"))
         evt.sdk = mod.createCohere(evt.options)
       }),
-    )
+    }
   }),
 })

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

@@ -1,16 +1,15 @@
 import { Effect } from "effect"
-import { define } from "@opencode-ai/plugin/v2/effect"
+import { PluginV2 } from "../../plugin"
 
-export const DeepInfraPlugin = define({
-  id: "deepinfra",
-  effect: Effect.fn(function* (ctx) {
-    yield* ctx.aisdk.hook(
-      "sdk",
-      Effect.fn(function* (evt) {
+export const DeepInfraPlugin = PluginV2.define({
+  id: PluginV2.ID.make("deepinfra"),
+  effect: Effect.gen(function* () {
+    return {
+      "aisdk.sdk": Effect.fn(function* (evt) {
         if (evt.package !== "@ai-sdk/deepinfra") return
         const mod = yield* Effect.promise(() => import("@ai-sdk/deepinfra"))
         evt.sdk = mod.createDeepInfra(evt.options)
       }),
-    )
+    }
   }),
 })

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

@@ -1,18 +1,19 @@
-import { Effect } from "effect"
+import { Npm } from "../../npm"
+import { Effect, Option } from "effect"
 import { pathToFileURL } from "url"
-import { define } from "@opencode-ai/plugin/v2/effect"
+import { PluginV2 } from "../../plugin"
 
-export const DynamicProviderPlugin = define({
-  id: "dynamic-provider",
-  effect: Effect.fn(function* (ctx) {
-    yield* ctx.aisdk.hook(
-      "sdk",
-      Effect.fn(function* (evt) {
+export const DynamicProviderPlugin = PluginV2.define({
+  id: PluginV2.ID.make("dynamic-provider"),
+  effect: Effect.gen(function* () {
+    const npm = yield* Npm.Service
+    return {
+      "aisdk.sdk": Effect.fn(function* (evt) {
         if (evt.sdk) return
 
         const installedPath = evt.package.startsWith("file://")
           ? evt.package
-          : (yield* ctx.npm.add(evt.package).pipe(Effect.orDie)).entrypoint
+          : Option.getOrUndefined((yield* npm.add(evt.package).pipe(Effect.orDie)).entrypoint)
         if (!installedPath) throw new Error(`Package ${evt.package} has no import entrypoint`)
 
         const mod = yield* Effect.promise(async () => {
@@ -25,6 +26,6 @@ export const DynamicProviderPlugin = define({
 
         evt.sdk = mod[match](evt.options)
       }),
-    )
+    }
   }),
 })

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

@@ -1,16 +1,15 @@
 import { Effect } from "effect"
-import { define } from "@opencode-ai/plugin/v2/effect"
+import { PluginV2 } from "../../plugin"
 
-export const GatewayPlugin = define({
-  id: "gateway",
-  effect: Effect.fn(function* (ctx) {
-    yield* ctx.aisdk.hook(
-      "sdk",
-      Effect.fn(function* (evt) {
+export const GatewayPlugin = PluginV2.define({
+  id: PluginV2.ID.make("gateway"),
+  effect: Effect.gen(function* () {
+    return {
+      "aisdk.sdk": Effect.fn(function* (evt) {
         if (evt.package !== "@ai-sdk/gateway") return
         const mod = yield* Effect.promise(() => import("@ai-sdk/gateway"))
         evt.sdk = mod.createGateway(evt.options)
       }),
-    )
+    }
   }),
 })

packages/core/src/plugin/provider/github-copilot.ts

@@ -1,6 +1,6 @@
 import { Effect } from "effect"
 import { ModelV2 } from "../../model"
-import { define } from "@opencode-ai/plugin/v2/effect"
+import { PluginV2 } from "../../plugin"
 import { ProviderV2 } from "../../provider"
 
 function shouldUseResponses(modelID: string) {
@@ -11,31 +11,16 @@ function shouldUseResponses(modelID: string) {
   return Number(match[1]) >= 5 && !modelID.startsWith("gpt-5-mini")
 }
 
-export const GithubCopilotPlugin = define({
-  id: "github-copilot",
-  effect: Effect.fn(function* (ctx) {
-    yield* ctx.catalog.transform(
-      Effect.fn(function* (evt) {
-        const item = evt.provider.get(ProviderV2.ID.githubCopilot)
-        if (!item || !item.models.has(ModelV2.ID.make("gpt-5-chat-latest"))) return
-        evt.model.update(item.provider.id, ModelV2.ID.make("gpt-5-chat-latest"), (model) => {
-          // This chat-only alias conflicts with the Copilot GPT-5 Responses route,
-          // so hide it only for Copilot rather than for every provider catalog.
-          model.enabled = false
-        })
-      }),
-    )
-    yield* ctx.aisdk.hook(
-      "sdk",
-      Effect.fn(function* (evt) {
+export const GithubCopilotPlugin = PluginV2.define({
+  id: PluginV2.ID.make("github-copilot"),
+  effect: Effect.gen(function* () {
+    return {
+      "aisdk.sdk": Effect.fn(function* (evt) {
         if (evt.package !== "@ai-sdk/github-copilot") return
         const mod = yield* Effect.promise(() => import("../../github-copilot/copilot-provider"))
         evt.sdk = mod.createOpenaiCompatible(evt.options)
       }),
-    )
-    yield* ctx.aisdk.hook(
-      "language",
-      Effect.fn(function* (evt) {
+      "aisdk.language": Effect.fn(function* (evt) {
         if (evt.model.providerID !== ProviderV2.ID.githubCopilot) return
         if (evt.sdk.responses === undefined && evt.sdk.chat === undefined) {
           evt.language = evt.sdk.languageModel(evt.model.api.id)
@@ -45,6 +30,15 @@ export const GithubCopilotPlugin = define({
           ? evt.sdk.responses(evt.model.api.id)
           : evt.sdk.chat(evt.model.api.id)
       }),
-    )
+      "catalog.transform": Effect.fn(function* (evt) {
+        const item = evt.provider.get(ProviderV2.ID.githubCopilot)
+        if (!item || !item.models.has(ModelV2.ID.make("gpt-5-chat-latest"))) return
+        evt.model.update(item.provider.id, ModelV2.ID.make("gpt-5-chat-latest"), (model) => {
+          // This chat-only alias conflicts with the Copilot GPT-5 Responses route,
+          // so hide it only for Copilot rather than for every provider catalog.
+          model.enabled = false
+        })
+      }),
+    }
   }),
 })

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

@@ -1,15 +1,14 @@
 import os from "os"
 import { InstallationVersion } from "../../installation/version"
 import { Effect } from "effect"
-import { define } from "@opencode-ai/plugin/v2/effect"
+import { PluginV2 } from "../../plugin"
 import { ProviderV2 } from "../../provider"
 
-export const GitLabPlugin = define({
-  id: "gitlab",
-  effect: Effect.fn(function* (ctx) {
-    yield* ctx.aisdk.hook(
-      "sdk",
-      Effect.fn(function* (evt) {
+export const GitLabPlugin = PluginV2.define({
+  id: PluginV2.ID.make("gitlab"),
+  effect: Effect.gen(function* () {
+    return {
+      "aisdk.sdk": Effect.fn(function* (evt) {
         if (evt.package !== "gitlab-ai-provider") return
         const mod = yield* Effect.promise(() => import("gitlab-ai-provider"))
         evt.sdk = mod.createGitLab({
@@ -31,10 +30,7 @@ export const GitLabPlugin = define({
           },
         })
       }),
-    )
-    yield* ctx.aisdk.hook(
-      "language",
-      Effect.fn(function* (evt) {
+      "aisdk.language": Effect.fn(function* (evt) {
         if (evt.model.providerID !== ProviderV2.ID.gitlab) return
         const featureFlags =
           typeof evt.options.featureFlags === "object" && evt.options.featureFlags ? evt.options.featureFlags : {}
@@ -62,6 +58,6 @@ export const GitLabPlugin = define({
           featureFlags,
         })
       }),
-    )
+    }
   }),
 })

packages/core/src/plugin/provider/google-vertex.ts

@@ -1,5 +1,5 @@
 import { Effect } from "effect"
-import { define } from "@opencode-ai/plugin/v2/effect"
+import { PluginV2 } from "../../plugin"
 import { ProviderV2 } from "../../provider"
 
 function resolveProject(options: Record<string, any>) {
@@ -54,11 +54,11 @@ function authFetch(fetchWithRuntimeOptions?: unknown) {
   }
 }
 
-export const GoogleVertexPlugin = define({
-  id: "google-vertex",
-  effect: Effect.fn(function* (ctx) {
-    yield* ctx.catalog.transform(
-      Effect.fn(function* (evt) {
+export const GoogleVertexPlugin = PluginV2.define({
+  id: PluginV2.ID.make("google-vertex"),
+  effect: Effect.gen(function* () {
+    return {
+      "catalog.transform": Effect.fn(function* (evt) {
         for (const item of evt.provider.list()) {
           if (item.provider.api.type !== "aisdk") continue
           if (
@@ -83,10 +83,7 @@ export const GoogleVertexPlugin = define({
           })
         }
       }),
-    )
-    yield* ctx.aisdk.hook(
-      "sdk",
-      Effect.fn(function* (evt) {
+      "aisdk.sdk": Effect.fn(function* (evt) {
         if (evt.model.providerID === ProviderV2.ID.googleVertex && evt.package.includes("@ai-sdk/openai-compatible")) {
           evt.options.fetch = authFetch(evt.options.fetch)
           return
@@ -103,22 +100,19 @@ export const GoogleVertexPlugin = define({
           location,
         })
       }),
-    )
-    yield* ctx.aisdk.hook(
-      "language",
-      Effect.fn(function* (evt) {
+      "aisdk.language": Effect.fn(function* (evt) {
         if (evt.model.providerID !== ProviderV2.ID.googleVertex) return
         evt.language = evt.sdk.languageModel(String(evt.model.api.id).trim())
       }),
-    )
+    }
   }),
 })
 
-export const GoogleVertexAnthropicPlugin = define({
-  id: "google-vertex-anthropic",
-  effect: Effect.fn(function* (ctx) {
-    yield* ctx.catalog.transform(
-      Effect.fn(function* (evt) {
+export const GoogleVertexAnthropicPlugin = PluginV2.define({
+  id: PluginV2.ID.make("google-vertex-anthropic"),
+  effect: Effect.gen(function* () {
+    return {
+      "catalog.transform": Effect.fn(function* (evt) {
         for (const item of evt.provider.list()) {
           if (item.provider.api.type !== "aisdk") continue
           if (item.provider.api.package !== "@ai-sdk/google-vertex/anthropic") continue
@@ -138,10 +132,7 @@ export const GoogleVertexAnthropicPlugin = define({
           })
         }
       }),
-    )
-    yield* ctx.aisdk.hook(
-      "sdk",
-      Effect.fn(function* (evt) {
+      "aisdk.sdk": Effect.fn(function* (evt) {
         if (evt.package !== "@ai-sdk/google-vertex/anthropic") return
         const mod = yield* Effect.promise(() => import("@ai-sdk/google-vertex/anthropic"))
         const project =
@@ -165,13 +156,10 @@ export const GoogleVertexAnthropicPlugin = define({
             : {}),
         })
       }),
-    )
-    yield* ctx.aisdk.hook(
-      "language",
-      Effect.fn(function* (evt) {
+      "aisdk.language": Effect.fn(function* (evt) {
         if (evt.model.providerID !== ProviderV2.ID.make("google-vertex-anthropic")) return
         evt.language = evt.sdk.languageModel(String(evt.model.api.id).trim())
       }),
-    )
+    }
   }),
 })

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

@@ -1,16 +1,15 @@
 import { Effect } from "effect"
-import { define } from "@opencode-ai/plugin/v2/effect"
+import { PluginV2 } from "../../plugin"
 
-export const GooglePlugin = define({
-  id: "google",
-  effect: Effect.fn(function* (ctx) {
-    yield* ctx.aisdk.hook(
-      "sdk",
-      Effect.fn(function* (evt) {
+export const GooglePlugin = PluginV2.define({
+  id: PluginV2.ID.make("google"),
+  effect: Effect.gen(function* () {
+    return {
+      "aisdk.sdk": Effect.fn(function* (evt) {
         if (evt.package !== "@ai-sdk/google") return
         const mod = yield* Effect.promise(() => import("@ai-sdk/google"))
         evt.sdk = mod.createGoogleGenerativeAI(evt.options)
       }),
-    )
+    }
   }),
 })

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

@@ -1,16 +1,15 @@
 import { Effect } from "effect"
-import { define } from "@opencode-ai/plugin/v2/effect"
+import { PluginV2 } from "../../plugin"
 
-export const GroqPlugin = define({
-  id: "groq",
-  effect: Effect.fn(function* (ctx) {
-    yield* ctx.aisdk.hook(
-      "sdk",
-      Effect.fn(function* (evt) {
+export const GroqPlugin = PluginV2.define({
+  id: PluginV2.ID.make("groq"),
+  effect: Effect.gen(function* () {
+    return {
+      "aisdk.sdk": Effect.fn(function* (evt) {
         if (evt.package !== "@ai-sdk/groq") return
         const mod = yield* Effect.promise(() => import("@ai-sdk/groq"))
         evt.sdk = mod.createGroq(evt.options)
       }),
-    )
+    }
   }),
 })

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

@@ -1,11 +1,11 @@
 import { Effect } from "effect"
-import { define } from "@opencode-ai/plugin/v2/effect"
+import { PluginV2 } from "../../plugin"
 
-export const KiloPlugin = define({
-  id: "kilo",
-  effect: Effect.fn(function* (ctx) {
-    yield* ctx.catalog.transform(
-      Effect.fn(function* (evt) {
+export const KiloPlugin = PluginV2.define({
+  id: PluginV2.ID.make("kilo"),
+  effect: Effect.gen(function* () {
+    return {
+      "catalog.transform": Effect.fn(function* (evt) {
         for (const item of evt.provider.list()) {
           if (item.provider.api.type !== "aisdk") continue
           if (item.provider.api.package !== "@ai-sdk/openai-compatible") continue
@@ -16,6 +16,6 @@ export const KiloPlugin = define({
           })
         }
       }),
-    )
+    }
   }),
 })

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

@@ -1,17 +1,19 @@
 import { Effect } from "effect"
-import { define } from "@opencode-ai/plugin/v2/effect"
+import { Integration } from "../../integration"
+import { PluginV2 } from "../../plugin"
 
-export const LLMGatewayPlugin = define({
-  id: "llmgateway",
-  effect: Effect.fn(function* (ctx) {
-    yield* ctx.catalog.transform(
-      Effect.fn(function* (evt) {
+export const LLMGatewayPlugin = PluginV2.define({
+  id: PluginV2.ID.make("llmgateway"),
+  effect: Effect.gen(function* () {
+    const integrations = yield* Integration.Service
+    return {
+      "catalog.transform": Effect.fn(function* (evt) {
         for (const item of evt.provider.list()) {
           if (item.provider.disabled) continue
+          if (!(yield* integrations.get(Integration.ID.make(item.provider.id)))) continue
           if (item.provider.api.type !== "aisdk") continue
           if (item.provider.api.package !== "@ai-sdk/openai-compatible") continue
           if (item.provider.api.url !== "https://api.llmgateway.io/v1") continue
-          if (!(yield* ctx.integration.get(item.provider.id))) continue
           evt.provider.update(item.provider.id, (provider) => {
             provider.request.headers["HTTP-Referer"] = "https://opencode.ai/"
             provider.request.headers["X-Title"] = "opencode"
@@ -19,6 +21,6 @@ export const LLMGatewayPlugin = define({
           })
         }
       }),
-    )
+    }
   }),
 })

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

@@ -1,16 +1,15 @@
 import { Effect } from "effect"
-import { define } from "@opencode-ai/plugin/v2/effect"
+import { PluginV2 } from "../../plugin"
 
-export const MistralPlugin = define({
-  id: "mistral",
-  effect: Effect.fn(function* (ctx) {
-    yield* ctx.aisdk.hook(
-      "sdk",
-      Effect.fn(function* (evt) {
+export const MistralPlugin = PluginV2.define({
+  id: PluginV2.ID.make("mistral"),
+  effect: Effect.gen(function* () {
+    return {
+      "aisdk.sdk": Effect.fn(function* (evt) {
         if (evt.package !== "@ai-sdk/mistral") return
         const mod = yield* Effect.promise(() => import("@ai-sdk/mistral"))
         evt.sdk = mod.createMistral(evt.options)
       }),
-    )
+    }
   }),
 })

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

@@ -1,11 +1,11 @@
 import { Effect } from "effect"
-import { define } from "@opencode-ai/plugin/v2/effect"
+import { PluginV2 } from "../../plugin"
 
-export const NvidiaPlugin = define({
-  id: "nvidia",
-  effect: Effect.fn(function* (ctx) {
-    yield* ctx.catalog.transform(
-      Effect.fn(function* (evt) {
+export const NvidiaPlugin = PluginV2.define({
+  id: PluginV2.ID.make("nvidia"),
+  effect: Effect.gen(function* () {
+    return {
+      "catalog.transform": Effect.fn(function* (evt) {
         for (const item of evt.provider.list()) {
           if (item.provider.api.type !== "aisdk") continue
           if (item.provider.api.package !== "@ai-sdk/openai-compatible") continue
@@ -17,6 +17,6 @@ export const NvidiaPlugin = define({
           })
         }
       }),
-    )
+    }
   }),
 })

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

@@ -1,18 +1,17 @@
 import { Effect } from "effect"
-import { define } from "@opencode-ai/plugin/v2/effect"
+import { PluginV2 } from "../../plugin"
 
-export const OpenAICompatiblePlugin = define({
-  id: "openai-compatible",
-  effect: Effect.fn(function* (ctx) {
-    yield* ctx.aisdk.hook(
-      "sdk",
-      Effect.fn(function* (evt) {
+export const OpenAICompatiblePlugin = PluginV2.define({
+  id: PluginV2.ID.make("openai-compatible"),
+  effect: Effect.gen(function* () {
+    return {
+      "aisdk.sdk": Effect.fn(function* (evt) {
         if (evt.sdk) return
         if (!evt.package.includes("@ai-sdk/openai-compatible")) return
         if (evt.options.includeUsage !== false) evt.options.includeUsage = true
         const mod = yield* Effect.promise(() => import("@ai-sdk/openai-compatible"))
         evt.sdk = mod.createOpenAICompatible(evt.options as any)
       }),
-    )
+    }
   }),
 })

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

@@ -1,20 +1,29 @@
 import { Effect } from "effect"
 import { ModelV2 } from "../../model"
-import { define } from "@opencode-ai/plugin/v2/effect"
+import { PluginV2 } from "../../plugin"
 import { ProviderV2 } from "../../provider"
 import { Integration } from "../../integration"
 import { browser, headless } from "./openai-auth"
 
-export const OpenAIPlugin = define({
-  id: "openai",
-  effect: Effect.fn(function* (ctx) {
+export const OpenAIPlugin = PluginV2.define({
+  id: PluginV2.ID.make("openai"),
+  effect: Effect.gen(function* () {
     const integrations = yield* Integration.Service
-    yield* integrations.transform((draft) => {
-      draft.method.update(browser)
-      draft.method.update(headless)
+    yield* integrations.update((editor) => {
+      editor.method.update(browser)
+      editor.method.update(headless)
     })
-    yield* ctx.catalog.transform(
-      Effect.fn(function* (evt) {
+    return {
+      "aisdk.sdk": Effect.fn(function* (evt) {
+        if (evt.package !== "@ai-sdk/openai") return
+        const mod = yield* Effect.promise(() => import("@ai-sdk/openai"))
+        evt.sdk = mod.createOpenAI(evt.options)
+      }),
+      "aisdk.language": Effect.fn(function* (evt) {
+        if (evt.model.providerID !== ProviderV2.ID.openai) return
+        evt.language = evt.sdk.responses(evt.model.api.id)
+      }),
+      "catalog.transform": Effect.fn(function* (evt) {
         for (const item of evt.provider.list()) {
           if (item.provider.api.type !== "aisdk") continue
           if (item.provider.api.package !== "@ai-sdk/openai") continue
@@ -26,21 +35,6 @@ export const OpenAIPlugin = define({
           })
         }
       }),
-    )
-    yield* ctx.aisdk.hook(
-      "sdk",
-      Effect.fn(function* (evt) {
-        if (evt.package !== "@ai-sdk/openai") return
-        const mod = yield* Effect.promise(() => import("@ai-sdk/openai"))
-        evt.sdk = mod.createOpenAI(evt.options)
-      }),
-    )
-    yield* ctx.aisdk.hook(
-      "language",
-      Effect.fn(function* (evt) {
-        if (evt.model.providerID !== ProviderV2.ID.openai) return
-        evt.language = evt.sdk.responses(evt.model.api.id)
-      }),
-    )
+    }
   }),
 })

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

@@ -1,16 +1,18 @@
 import { Effect } from "effect"
-import { define } from "@opencode-ai/plugin/v2/effect"
+import { Integration } from "../../integration"
+import { PluginV2 } from "../../plugin"
 import { ProviderV2 } from "../../provider"
 
-export const OpencodePlugin = define({
-  id: "opencode",
-  effect: Effect.fn(function* (ctx) {
+export const OpencodePlugin = PluginV2.define({
+  id: PluginV2.ID.make("opencode"),
+  effect: Effect.gen(function* () {
+    const integrations = yield* Integration.Service
     let hasKey = false
-    yield* ctx.catalog.transform(
-      Effect.fn(function* (evt) {
+    return {
+      "catalog.transform": Effect.fn(function* (evt) {
         const item = evt.provider.get(ProviderV2.ID.opencode)
         if (!item) return
-        const integration = yield* ctx.integration.get(item.provider.id)
+        const integration = yield* integrations.get(Integration.ID.make(item.provider.id))
         hasKey = Boolean(
           process.env.OPENCODE_API_KEY || integration?.connections.length || item.provider.request.body.apiKey,
         )
@@ -25,6 +27,6 @@ export const OpencodePlugin = define({
           })
         }
       }),
-    )
+    }
   }),
 })

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

@@ -1,12 +1,12 @@
 import { Effect } from "effect"
 import { ModelV2 } from "../../model"
-import { define } from "@opencode-ai/plugin/v2/effect"
+import { PluginV2 } from "../../plugin"
 
-export const OpenRouterPlugin = define({
-  id: "openrouter",
-  effect: Effect.fn(function* (ctx) {
-    yield* ctx.catalog.transform(
-      Effect.fn(function* (evt) {
+export const OpenRouterPlugin = PluginV2.define({
+  id: PluginV2.ID.make("openrouter"),
+  effect: Effect.gen(function* () {
+    return {
+      "catalog.transform": Effect.fn(function* (evt) {
         for (const item of evt.provider.list()) {
           if (item.provider.api.type !== "aisdk") continue
           if (item.provider.api.package !== "@openrouter/ai-sdk-provider") continue
@@ -24,14 +24,11 @@ export const OpenRouterPlugin = define({
           }
         }
       }),
-    )
-    yield* ctx.aisdk.hook(
-      "sdk",
-      Effect.fn(function* (evt) {
+      "aisdk.sdk": Effect.fn(function* (evt) {
         if (evt.package !== "@openrouter/ai-sdk-provider") return
         const mod = yield* Effect.promise(() => import("@openrouter/ai-sdk-provider"))
         evt.sdk = mod.createOpenRouter(evt.options)
       }),
-    )
+    }
   }),
 })

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

@@ -1,16 +1,15 @@
 import { Effect } from "effect"
-import { define } from "@opencode-ai/plugin/v2/effect"
+import { PluginV2 } from "../../plugin"
 
-export const PerplexityPlugin = define({
-  id: "perplexity",
-  effect: Effect.fn(function* (ctx) {
-    yield* ctx.aisdk.hook(
-      "sdk",
-      Effect.fn(function* (evt) {
+export const PerplexityPlugin = PluginV2.define({
+  id: PluginV2.ID.make("perplexity"),
+  effect: Effect.gen(function* () {
+    return {
+      "aisdk.sdk": Effect.fn(function* (evt) {
         if (evt.package !== "@ai-sdk/perplexity") return
         const mod = yield* Effect.promise(() => import("@ai-sdk/perplexity"))
         evt.sdk = mod.createPerplexity(evt.options)
       }),
-    )
+    }
   }),
 })

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

@@ -1,14 +1,15 @@
-import { Effect } from "effect"
+import { Npm } from "../../npm"
+import { Effect, Option } from "effect"
 import { pathToFileURL } from "url"
-import { define } from "@opencode-ai/plugin/v2/effect"
+import { PluginV2 } from "../../plugin"
 import { ProviderV2 } from "../../provider"
 
-export const SapAICorePlugin = define({
-  id: "sap-ai-core",
-  effect: Effect.fn(function* (ctx) {
-    yield* ctx.aisdk.hook(
-      "sdk",
-      Effect.fn(function* (evt) {
+export const SapAICorePlugin = PluginV2.define({
+  id: PluginV2.ID.make("sap-ai-core"),
+  effect: Effect.gen(function* () {
+    const npm = yield* Npm.Service
+    return {
+      "aisdk.sdk": Effect.fn(function* (evt) {
         if (evt.model.providerID !== ProviderV2.ID.make("sap-ai-core")) return
         const serviceKey =
           process.env.AICORE_SERVICE_KEY ??
@@ -17,7 +18,7 @@ export const SapAICorePlugin = define({
 
         const installedPath = evt.package.startsWith("file://")
           ? evt.package
-          : (yield* ctx.npm.add(evt.package).pipe(Effect.orDie)).entrypoint
+          : Option.getOrUndefined((yield* npm.add(evt.package).pipe(Effect.orDie)).entrypoint)
         if (!installedPath) throw new Error(`Package ${evt.package} has no import entrypoint`)
 
         const mod = yield* Effect.promise(async () => {
@@ -34,13 +35,10 @@ export const SapAICorePlugin = define({
             : {},
         )
       }),
-    )
-    yield* ctx.aisdk.hook(
-      "language",
-      Effect.fn(function* (evt) {
+      "aisdk.language": Effect.fn(function* (evt) {
         if (evt.model.providerID !== ProviderV2.ID.make("sap-ai-core")) return
         evt.language = evt.sdk(evt.model.api.id)
       }),
-    )
+    }
   }),
 })

packages/core/src/plugin/provider/snowflake-cortex.ts

@@ -1,5 +1,5 @@
 import { Effect } from "effect"
-import { define } from "@opencode-ai/plugin/v2/effect"
+import { PluginV2 } from "../../plugin"
 import { ProviderV2 } from "../../provider"
 
 type FetchLike = (url: string | URL | Request, init?: RequestInit) => Promise<Response>
@@ -64,12 +64,11 @@ export function cortexFetch(upstream: FetchLike = fetch) {
   }
 }
 
-export const SnowflakeCortexPlugin = define({
-  id: "snowflake-cortex",
-  effect: Effect.fn(function* (ctx) {
-    yield* ctx.aisdk.hook(
-      "sdk",
-      Effect.fn(function* (evt) {
+export const SnowflakeCortexPlugin = PluginV2.define({
+  id: PluginV2.ID.make("snowflake-cortex"),
+  effect: Effect.gen(function* () {
+    return {
+      "aisdk.sdk": Effect.fn(function* (evt) {
         if (evt.model.providerID !== ProviderV2.ID.make("snowflake-cortex")) return
         const token =
           process.env.SNOWFLAKE_CORTEX_TOKEN ??
@@ -85,6 +84,6 @@ export const SnowflakeCortexPlugin = define({
           fetch: cortexFetch(upstream) as typeof fetch,
         } as any)
       }),
-    )
+    }
   }),
 })

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

@@ -1,16 +1,15 @@
 import { Effect } from "effect"
-import { define } from "@opencode-ai/plugin/v2/effect"
+import { PluginV2 } from "../../plugin"
 
-export const TogetherAIPlugin = define({
-  id: "togetherai",
-  effect: Effect.fn(function* (ctx) {
-    yield* ctx.aisdk.hook(
-      "sdk",
-      Effect.fn(function* (evt) {
+export const TogetherAIPlugin = PluginV2.define({
+  id: PluginV2.ID.make("togetherai"),
+  effect: Effect.gen(function* () {
+    return {
+      "aisdk.sdk": Effect.fn(function* (evt) {
         if (evt.package !== "@ai-sdk/togetherai") return
         const mod = yield* Effect.promise(() => import("@ai-sdk/togetherai"))
         evt.sdk = mod.createTogetherAI(evt.options)
       }),
-    )
+    }
   }),
 })

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

@@ -1,16 +1,15 @@
 import { Effect } from "effect"
-import { define } from "@opencode-ai/plugin/v2/effect"
+import { PluginV2 } from "../../plugin"
 
-export const VenicePlugin = define({
-  id: "venice",
-  effect: Effect.fn(function* (ctx) {
-    yield* ctx.aisdk.hook(
-      "sdk",
-      Effect.fn(function* (evt) {
+export const VenicePlugin = PluginV2.define({
+  id: PluginV2.ID.make("venice"),
+  effect: Effect.gen(function* () {
+    return {
+      "aisdk.sdk": Effect.fn(function* (evt) {
         if (evt.package !== "venice-ai-sdk-provider") return
         const mod = yield* Effect.promise(() => import("venice-ai-sdk-provider"))
         evt.sdk = mod.createVenice(evt.options)
       }),
-    )
+    }
   }),
 })

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

@@ -1,11 +1,11 @@
 import { Effect } from "effect"
-import { define } from "@opencode-ai/plugin/v2/effect"
+import { PluginV2 } from "../../plugin"
 
-export const VercelPlugin = define({
-  id: "vercel",
-  effect: Effect.fn(function* (ctx) {
-    yield* ctx.catalog.transform(
-      Effect.fn(function* (evt) {
+export const VercelPlugin = PluginV2.define({
+  id: PluginV2.ID.make("vercel"),
+  effect: Effect.gen(function* () {
+    return {
+      "catalog.transform": Effect.fn(function* (evt) {
         for (const item of evt.provider.list()) {
           if (item.provider.api.type !== "aisdk") continue
           if (item.provider.api.package !== "@ai-sdk/vercel") continue
@@ -15,14 +15,11 @@ export const VercelPlugin = define({
           })
         }
       }),
-    )
-    yield* ctx.aisdk.hook(
-      "sdk",
-      Effect.fn(function* (evt) {
+      "aisdk.sdk": Effect.fn(function* (evt) {
         if (evt.package !== "@ai-sdk/vercel") return
         const mod = yield* Effect.promise(() => import("@ai-sdk/vercel"))
         evt.sdk = mod.createVercel(evt.options)
       }),
-    )
+    }
   }),
 })

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

@@ -1,24 +1,20 @@
 import { Effect } from "effect"
-import { define } from "@opencode-ai/plugin/v2/effect"
+import { PluginV2 } from "../../plugin"
 import { ProviderV2 } from "../../provider"
 
-export const XAIPlugin = define({
-  id: "xai",
-  effect: Effect.fn(function* (ctx) {
-    yield* ctx.aisdk.hook(
-      "sdk",
-      Effect.fn(function* (evt) {
+export const XAIPlugin = PluginV2.define({
+  id: PluginV2.ID.make("xai"),
+  effect: Effect.gen(function* () {
+    return {
+      "aisdk.sdk": Effect.fn(function* (evt) {
         if (evt.package !== "@ai-sdk/xai") return
         const mod = yield* Effect.promise(() => import("@ai-sdk/xai"))
         evt.sdk = mod.createXai(evt.options)
       }),
-    )
-    yield* ctx.aisdk.hook(
-      "language",
-      Effect.fn(function* (evt) {
+      "aisdk.language": Effect.fn(function* (evt) {
         if (evt.model.providerID !== ProviderV2.ID.make("xai")) return
         evt.language = evt.sdk.responses(evt.model.api.id)
       }),
-    )
+    }
   }),
 })

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

@@ -1,11 +1,11 @@
 import { Effect } from "effect"
-import { define } from "@opencode-ai/plugin/v2/effect"
+import { PluginV2 } from "../../plugin"
 
-export const ZenmuxPlugin = define({
-  id: "zenmux",
-  effect: Effect.fn(function* (ctx) {
-    yield* ctx.catalog.transform(
-      Effect.fn(function* (evt) {
+export const ZenmuxPlugin = PluginV2.define({
+  id: PluginV2.ID.make("zenmux"),
+  effect: Effect.gen(function* () {
+    return {
+      "catalog.transform": Effect.fn(function* (evt) {
         for (const item of evt.provider.list()) {
           if (item.provider.api.type !== "aisdk") continue
           if (item.provider.api.package !== "@ai-sdk/openai-compatible") continue
@@ -16,6 +16,6 @@ export const ZenmuxPlugin = define({
           })
         }
       }),
-    )
+    }
   }),
 })

packages/core/src/plugin/skill.ts

@@ -2,19 +2,22 @@
 
 export * as SkillPlugin from "./skill"
 
-import { define } from "@opencode-ai/plugin/v2/effect"
 import { Effect } from "effect"
+import { PluginV2 } from "../plugin"
 import { AbsolutePath } from "../schema"
 import { SkillV2 } from "../skill"
 import customizeOpencodeContent from "./skill/customize-opencode.md" with { type: "text" }
 
 export const CustomizeOpencodeContent = customizeOpencodeContent
 
-export const Plugin = define({
-  id: "skill",
-  effect: Effect.fn(function* (ctx) {
-    yield* ctx.skill.transform((draft) => {
-      draft.source(
+export const Plugin = PluginV2.define({
+  id: PluginV2.ID.make("skill"),
+  effect: Effect.gen(function* () {
+    const skill = yield* SkillV2.Service
+    const transform = yield* skill.transform()
+
+    yield* transform((editor) => {
+      editor.source(
         new SkillV2.EmbeddedSource({
           type: "embedded",
           skill: new SkillV2.Info({

packages/core/src/provider.ts

@@ -1,7 +1,7 @@
 export * as ProviderV2 from "./provider"
 
 import { withStatics } from "./schema"
-import { Schema, Types } from "effect"
+import { Schema } from "effect"
 
 export const ID = Schema.String.pipe(
   Schema.brand("ProviderV2.ID"),
@@ -37,9 +37,6 @@ export const Native = Schema.Struct({
 
 export const Api = Schema.Union([AISDK, Native]).pipe(Schema.toTaggedUnion("type"))
 export type Api = typeof Api.Type
-export type MutableApi<T extends Api = Api> = T extends Api
-  ? Omit<Types.DeepMutable<T>, "settings"> & (undefined extends T["settings"] ? { settings?: any } : { settings: any })
-  : never
 
 export const Request = Schema.Struct({
   headers: Schema.Record(Schema.String, Schema.String),
@@ -69,5 +66,3 @@ export class Info extends Schema.Class<Info>("ProviderV2.Info")({
     })
   }
 }
-
-export type MutableInfo = Omit<Types.DeepMutable<Info>, "api"> & { api: MutableApi }

packages/core/src/public/opencode.ts

@@ -1,9 +1,11 @@
 export * as OpenCode from "./opencode"
 
 import { Context, Effect, Layer } from "effect"
+import { Catalog } from "../catalog"
 import { Database } from "../database/database"
 import { EventV2 } from "../event"
 import { LocationServiceMap } from "../location-layer"
+import { PluginBoot } from "../plugin/boot"
 import { ProjectV2 } from "../project"
 import { SessionV2 } from "../session"
 import * as SessionExecutionLocal from "../session/execution/local"
@@ -21,22 +23,69 @@ export interface Interface {
 /** Intentional public native API for Effect applications embedding OpenCode. */
 export class Service extends Context.Service<Service, Interface>()("@opencode/public/OpenCode") {}
 
-const SessionsLayer = SessionV2.layer.pipe(
-  Layer.provide(SessionProjector.layer),
-  Layer.provide(SessionExecutionLocal.layer),
-  Layer.provide(SessionStore.layer),
-  Layer.provide(EventV2.layer),
-  Layer.provide(Database.defaultLayer),
-  Layer.provide(ProjectV2.defaultLayer),
-  Layer.provide(LocationServiceMap.layer.pipe(Layer.provide(ApplicationTools.layer))),
-  Layer.orDie,
+class SessionModelValidation extends Context.Service<
+  SessionModelValidation,
+  {
+    readonly validate: (
+      input: Session.SwitchModelInput & { readonly location: Session.Info["location"] },
+    ) => Effect.Effect<void, Session.ModelUnavailableError | Session.VariantUnavailableError>
+  }
+>()("@opencode/public/OpenCode/SessionModelValidation") {}
+
+const ApplicationToolsLayer = ApplicationTools.layer
+const LocationServicesLayer = LocationServiceMap.layer.pipe(Layer.provide(ApplicationToolsLayer))
+const SessionModelValidationLayer = Layer.effect(
+  SessionModelValidation,
+  Effect.gen(function* () {
+    const locations = yield* LocationServiceMap
+    return SessionModelValidation.of({
+      validate: Effect.fn("OpenCode.sessions.validateModel")(function* (input) {
+        yield* Effect.gen(function* () {
+          yield* (yield* PluginBoot.Service).wait()
+          const catalog = yield* Catalog.Service
+          const model = (yield* catalog.model.available()).find(
+            (model) => model.providerID === input.model.providerID && model.id === input.model.id,
+          )
+          if (!model)
+            return yield* new Session.ModelUnavailableError({
+              providerID: input.model.providerID,
+              modelID: input.model.id,
+            })
+          if (
+            input.model.variant !== undefined &&
+            input.model.variant !== "default" &&
+            !model.variants.some((variant) => variant.id === input.model.variant)
+          )
+            return yield* new Session.VariantUnavailableError({
+              providerID: input.model.providerID,
+              modelID: input.model.id,
+              variant: input.model.variant,
+            })
+        }).pipe(Effect.provide(locations.get(input.location)))
+      }),
+    })
+  }),
 )
+
+const SessionsLayer = Layer.merge(
+  SessionV2.layer.pipe(
+    Layer.provide(SessionProjector.layer),
+    Layer.provide(SessionExecutionLocal.layer),
+    Layer.provide(SessionStore.layer),
+    Layer.provide(EventV2.layer),
+    Layer.provide(Database.defaultLayer),
+    Layer.provide(ProjectV2.defaultLayer),
+    Layer.orDie,
+  ),
+  SessionModelValidationLayer,
+).pipe(Layer.provide(LocationServicesLayer))
 // TODO: Accept explicit storage so tests and embeddings can select disposable or application-owned persistence.
 export const layer = Layer.effect(
   Service,
   Effect.gen(function* () {
     const sessions = yield* SessionV2.Service
     const tools = yield* ApplicationTools.Service
+    const validation = yield* SessionModelValidation
     return Service.of({
       tools: { register: tools.register },
       sessions: {
@@ -49,7 +98,11 @@ export const layer = Layer.effect(
           }),
         get: sessions.get,
         list: sessions.list,
-        switchModel: sessions.switchModel,
+        switchModel: Effect.fn("OpenCode.sessions.switchModel")(function* (input) {
+          const session = yield* sessions.get(input.sessionID)
+          yield* validation.validate({ ...input, location: session.location })
+          yield* sessions.switchModel(input)
+        }),
         interrupt: sessions.interrupt,
         prompt: (input) =>
           sessions.prompt({
@@ -71,6 +124,6 @@ export const layer = Layer.effect(
       },
     })
   }),
-).pipe(Layer.provide(Layer.merge(ApplicationTools.layer, SessionsLayer)))
+).pipe(Layer.provide(Layer.merge(ApplicationToolsLayer, SessionsLayer)))
 
 // TODO: Add OpenCode.create(...) as the Promise facade over the same native API semantics.

packages/core/src/public/session.ts

@@ -1,6 +1,8 @@
 export * as Session from "./session"
 
-import { Effect, Stream } from "effect"
+import { Effect, Schema, Stream } from "effect"
+import { EventV2 } from "../event"
+import { ModelV2 } from "../model"
 import { SessionV2 } from "../session"
 import { MessageDecodeError } from "../session/error"
 import { SessionEvent } from "../session/event"
@@ -32,7 +34,9 @@ export type Delivery = SessionInput.Delivery
 export const ListInput = SessionV2.ListInput
 export type ListInput = SessionV2.ListInput
 
-export type Event = SessionEvent.DurableEvent
+export const EventCursor = EventV2.Cursor
+export type EventCursor = EventV2.Cursor
+export type Event = EventV2.CursorEvent<SessionEvent.DurableEvent>
 
 export const NotFoundError = SessionV2.NotFoundError
 export type NotFoundError = SessionV2.NotFoundError
@@ -40,6 +44,23 @@ export type NotFoundError = SessionV2.NotFoundError
 export const PromptConflictError = SessionV2.PromptConflictError
 export type PromptConflictError = SessionV2.PromptConflictError
 
+export class ModelUnavailableError extends Schema.TaggedErrorClass<ModelUnavailableError>()(
+  "Session.ModelUnavailableError",
+  {
+    providerID: Model.Ref.fields.providerID,
+    modelID: Model.Ref.fields.id,
+  },
+) {}
+
+export class VariantUnavailableError extends Schema.TaggedErrorClass<VariantUnavailableError>()(
+  "Session.VariantUnavailableError",
+  {
+    providerID: Model.Ref.fields.providerID,
+    modelID: Model.Ref.fields.id,
+    variant: ModelV2.VariantID,
+  },
+) {}
+
 export { MessageDecodeError }
 
 export interface CreateInput {
@@ -78,7 +99,7 @@ export interface MessageInput {
 
 export interface EventsInput {
   readonly sessionID: ID
-  readonly after?: number
+  readonly after?: EventCursor
 }
 
 export interface Interface {
@@ -86,7 +107,9 @@ export interface Interface {
   readonly get: (sessionID: ID) => Effect.Effect<Info, NotFoundError>
   readonly list: (input?: ListInput) => Effect.Effect<Info[]>
   readonly prompt: (input: PromptInput) => Effect.Effect<Admission, NotFoundError | PromptConflictError>
-  readonly switchModel: (input: SwitchModelInput) => Effect.Effect<void, NotFoundError>
+  readonly switchModel: (
+    input: SwitchModelInput,
+  ) => Effect.Effect<void, NotFoundError | ModelUnavailableError | VariantUnavailableError>
   /** Interrupt the active V2 execution chain for one Session on this process. Interrupting an idle or missing Session is a no-op. */
   readonly interrupt: (sessionID: ID) => Effect.Effect<void>
   readonly messages: (input: MessagesInput) => Effect.Effect<Message[], NotFoundError | MessageDecodeError>

packages/core/src/reference.ts

@@ -1,6 +1,7 @@
 export * as Reference from "./reference"
 
-import { Context, Effect, Layer, Schema, Scope, Types } from "effect"
+import { Context, Effect, Layer, Schema, Scope } from "effect"
+import { castDraft } from "immer"
 import { Global } from "./global"
 import { EventV2 } from "./event"
 import { Repository } from "./repository"
@@ -39,16 +40,17 @@ export class Info extends Schema.Class<Info>("Reference.Info")({
 }) {}
 
 type Data = {
-  sources: Map<string, Types.DeepMutable<Source>>
+  sources: Map<string, Source>
 }
 
-type Draft = {
+type Editor = {
   add(name: string, source: Source): void
   remove(name: string): void
   list(): readonly [string, Source][]
 }
 
-export interface Interface extends State.Transformable<Draft> {
+export interface Interface {
+  readonly transform: State.Interface<Data, Editor>["transform"]
   readonly list: () => Effect.Effect<Info[]>
 }
 
@@ -62,18 +64,18 @@ export const layer = Layer.effect(
     const cache = yield* RepositoryCache.Service
     const scope = yield* Scope.Scope
     const materialized = new Map<string, Info>()
-    const state = State.create<Data, Draft>({
+    const state = State.create<Data, Editor>({
       initial: () => ({ sources: new Map() }),
-      draft: (draft) => ({
-        add: (name, source) => draft.sources.set(name, source as Types.DeepMutable<Source>),
+      editor: (draft) => ({
+        add: (name, source) => draft.sources.set(name, castDraft(source)),
         remove: (name) => draft.sources.delete(name),
         list: () => Array.from(draft.sources.entries()) as [string, Source][],
       }),
-      finalize: (draft) =>
+      finalize: (editor) =>
         Effect.gen(function* () {
           materialized.clear()
           const seen = new Map<string, string | undefined>()
-          for (const [name, source] of draft.list()) {
+          for (const [name, source] of editor.list()) {
             if (source.type === "local") {
               materialized.set(
                 name,
@@ -126,7 +128,6 @@ export const layer = Layer.effect(
 
     return Service.of({
       transform: state.transform,
-      rebuild: state.rebuild,
       list: Effect.fn("Reference.list")(function* () {
         return Array.from(materialized.values())
       }),

packages/core/src/session.ts

@@ -1,8 +1,8 @@
 export * as SessionV2 from "./session"
 export * from "./session/schema"
 
-import { DateTime, Effect, Layer, Schema, Context, Stream } from "effect"
-import { and, asc, desc, eq, gt, gte, like, lt, or, type SQL } from "drizzle-orm"
+import { Cause, DateTime, Effect, Layer, Schema, Context, Stream } from "effect"
+import { and, asc, desc, eq, gt, like, lt, or, type SQL } from "drizzle-orm"
 import { ProjectV2 } from "./project"
 import { WorkspaceV2 } from "./workspace"
 import { ModelV2 } from "./model"
@@ -25,6 +25,7 @@ import { fromRow } from "./session/info"
 import { SessionRunner } from "./session/runner/index"
 import { SessionStore } from "./session/store"
 import { SessionExecution } from "./session/execution"
+import { logFailure } from "./session/logging"
 import { MessageDecodeError } from "./session/error"
 import { SessionEvent } from "./session/event"
 import { SessionInput } from "./session/input"
@@ -123,9 +124,12 @@ export interface Interface {
   ) => Effect.Effect<SessionMessage.Message[], NotFoundError | MessageDecodeError>
   readonly events: (input: {
     sessionID: SessionSchema.ID
-    after?: number
-  }) => Stream.Stream<SessionEvent.DurableEvent, NotFoundError>
-  readonly switchAgent: (input: { sessionID: SessionSchema.ID; agent: string }) => Effect.Effect<void, NotFoundError>
+    after?: EventV2.Cursor
+  }) => Stream.Stream<EventV2.CursorEvent<SessionEvent.DurableEvent>, NotFoundError>
+  readonly switchAgent: (input: {
+    sessionID: SessionSchema.ID
+    agent: string
+  }) => Effect.Effect<void, OperationUnavailableError>
   readonly switchModel: (input: {
     sessionID: SessionSchema.ID
     model: ModelV2.Ref
@@ -167,6 +171,20 @@ export const layer = Layer.effect(
     const store = yield* SessionStore.Service
     const decodeMessage = Schema.decodeUnknownEffect(SessionMessage.Message)
     const isDurableSessionEvent = Schema.is(SessionEvent.Durable)
+    const scope = yield* Effect.scope
+
+    const enqueueWake = (admitted: SessionInput.Admitted) =>
+      execution.wake(admitted.sessionID, admitted.admittedSeq).pipe(
+        Effect.tapCause((cause) =>
+          Cause.hasInterruptsOnly(cause)
+            ? Effect.void
+            : logFailure("Failed to wake Session", admitted.sessionID, cause),
+        ),
+        Effect.ignore,
+        Effect.forkIn(scope, { startImmediately: true }),
+        Effect.asVoid,
+      )
+
     const decode = (row: typeof SessionMessageTable.$inferSelect) =>
       decodeMessage({ ...row.data, id: row.id, type: row.type }).pipe(
         Effect.mapError(
@@ -248,13 +266,6 @@ export const layer = Layer.effect(
         if ("directory" in input) conditions.push(eq(SessionTable.directory, input.directory))
         if (input.workspaceID) conditions.push(eq(SessionTable.workspace_id, input.workspaceID))
         if ("project" in input) conditions.push(eq(SessionTable.project_id, input.project))
-        if ("subpath" in input && input.subpath)
-          conditions.push(
-            or(
-              eq(SessionTable.path, input.subpath),
-              and(gte(SessionTable.path, `${input.subpath}/`), lt(SessionTable.path, `${input.subpath}0`)),
-            )!,
-          )
         if (input.search) conditions.push(like(SessionTable.title, `%${input.search}%`))
         if (input.anchor) {
           conditions.push(
@@ -328,12 +339,20 @@ export const layer = Layer.effect(
         Stream.unwrap(
           result
             .get(input.sessionID)
-            .pipe(Effect.as(events.durable({ aggregateID: input.sessionID, after: input.after }))),
-        ).pipe(Stream.filter((event): event is SessionEvent.DurableEvent => isDurableSessionEvent(event))),
+            .pipe(Effect.as(events.aggregateEvents({ aggregateID: input.sessionID, after: input.after }))),
+        ).pipe(
+          Stream.filter((event): event is EventV2.CursorEvent<SessionEvent.DurableEvent> =>
+            isDurableSessionEvent(event.event),
+          ),
+        ),
       prompt: Effect.fn("V2Session.prompt")((input) =>
         Effect.uninterruptible(
           Effect.gen(function* () {
             yield* result.get(input.sessionID)
+            const returnPrompt = Effect.fnUntraced(function* (admitted: SessionInput.Admitted) {
+              if (input.resume !== false) yield* enqueueWake(admitted)
+              return admitted
+            }, Effect.uninterruptible)
             const messageID = input.id ?? SessionMessage.ID.create()
             const delivery = input.delivery ?? "steer"
             const expected = { sessionID: input.sessionID, messageID, prompt: input.prompt, delivery }
@@ -351,8 +370,7 @@ export const layer = Layer.effect(
             )
             if (!SessionInput.equivalent(admitted, expected))
               return yield* new PromptConflictError({ sessionID: input.sessionID, messageID })
-            if (input.resume !== false) yield* execution.wake(admitted.sessionID)
-            return admitted
+            return yield* returnPrompt(admitted)
           }),
         ),
       ),
@@ -362,14 +380,8 @@ export const layer = Layer.effect(
       skill: Effect.fn("V2Session.skill")(function* () {
         return yield* new OperationUnavailableError({ operation: "skill" })
       }),
-      switchAgent: Effect.fn("V2Session.switchAgent")(function* (input) {
-        yield* result.get(input.sessionID)
-        yield* events.publish(SessionEvent.AgentSwitched, {
-          sessionID: input.sessionID,
-          messageID: SessionMessage.ID.create(),
-          timestamp: yield* DateTime.now,
-          agent: input.agent,
-        })
+      switchAgent: Effect.fn("V2Session.switchAgent")(function* () {
+        return yield* new OperationUnavailableError({ operation: "switchAgent" })
       }),
       switchModel: Effect.fn("V2Session.switchModel")(function* (input) {
         yield* result.get(input.sessionID)
@@ -393,7 +405,19 @@ export const layer = Layer.effect(
         yield* execution.resume(sessionID)
       }),
       interrupt: Effect.fn("V2Session.interrupt")((sessionID) =>
-        Effect.uninterruptible(execution.interrupt(sessionID)),
+        Effect.uninterruptible(
+          Effect.gen(function* () {
+            const session = yield* store.get(sessionID)
+            if (!session) return yield* execution.interrupt(sessionID)
+            const event = yield* events.publish(SessionEvent.InterruptRequested, {
+              sessionID,
+              timestamp: yield* DateTime.now,
+            })
+            if (event.seq === undefined)
+              return yield* Effect.die("Interrupt request event is missing aggregate sequence")
+            yield* execution.interrupt(sessionID, event.seq)
+          }),
+        ),
       ),
     })
 

packages/core/src/session/context-epoch.ts

@@ -1,31 +1,54 @@
 export * as SessionContextEpoch from "./context-epoch"
 
-import { eq } from "drizzle-orm"
+import { and, eq, isNull, lt, or, sql } from "drizzle-orm"
 import { DateTime, Effect, Schema } from "effect"
+import { AgentV2 } from "../agent"
 import type { Database } from "../database/database"
 import { EventV2 } from "../event"
+import { Location } from "../location"
 import { SystemContext } from "../system-context/index"
 import { ContextSnapshotDecodeError } from "./error"
 import { SessionEvent } from "./event"
-import { SessionHistory } from "./history"
 import { SessionInput } from "./input"
 import { SessionMessageID } from "./message-id"
 import { SessionSchema } from "./schema"
-import { SessionContextEpochTable } from "./sql"
+import { SessionContextEpochTable, SessionTable } from "./sql"
 
 type DatabaseService = Database.Interface["db"]
 
+class RevisionMismatch extends Error {}
+class LocationMismatch extends Error {}
+export class AgentMismatch extends Error {}
+export class AgentReplacementBlocked extends Schema.TaggedErrorClass<AgentReplacementBlocked>()(
+  "SessionContextEpoch.AgentReplacementBlocked",
+  { sessionID: SessionSchema.ID, previous: AgentV2.ID, current: AgentV2.ID },
+) {}
+
+const retryRevisionMismatch = <A, E>(attempt: () => Effect.Effect<A, E>): Effect.Effect<A, E> =>
+  attempt().pipe(
+    Effect.catchDefect((defect) =>
+      defect instanceof RevisionMismatch
+        ? Effect.yieldNow.pipe(Effect.andThen(retryRevisionMismatch(attempt)))
+        : Effect.die(defect),
+    ),
+  )
+
 interface Prepared {
   readonly baseline: string
   readonly baselineSeq: number
+  readonly revision: number
 }
 
 export function initialize(
   db: DatabaseService,
   context: Effect.Effect<SystemContext.SystemContext>,
   sessionID: SessionSchema.ID,
+  location: Location.Ref,
+  agent: AgentV2.ID,
 ): Effect.Effect<Prepared | undefined, SystemContext.InitializationBlocked> {
-  return initializeOnce(db, context, sessionID).pipe(Effect.withSpan("SessionContextEpoch.initialize"))
+  return retryRevisionMismatch(() => initializeOnce(db, context, sessionID, location, agent)).pipe(
+    Effect.withSpan("SessionContextEpoch.initialize"),
+  )
 }
 
 export function prepare(
@@ -33,8 +56,12 @@ export function prepare(
   events: EventV2.Interface,
   context: Effect.Effect<SystemContext.SystemContext>,
   sessionID: SessionSchema.ID,
-): Effect.Effect<Prepared, SystemContext.InitializationBlocked | ContextSnapshotDecodeError> {
-  return prepareOnce(db, events, context, sessionID).pipe(Effect.withSpan("SessionContextEpoch.prepare"))
+  location: Location.Ref,
+  agent: AgentV2.ID,
+): Effect.Effect<Prepared, SystemContext.InitializationBlocked | ContextSnapshotDecodeError | AgentReplacementBlocked> {
+  return retryRevisionMismatch(() => prepareOnce(db, events, context, sessionID, location, agent)).pipe(
+    Effect.withSpan("SessionContextEpoch.prepare"),
+  )
 }
 
 const prepareOnce = Effect.fnUntraced(function* (
@@ -42,50 +69,57 @@ const prepareOnce = Effect.fnUntraced(function* (
   events: EventV2.Interface,
   context: Effect.Effect<SystemContext.SystemContext>,
   sessionID: SessionSchema.ID,
+  location: Location.Ref,
+  agent: AgentV2.ID,
 ) {
-  const [value, stored, compaction] = yield* Effect.all(
-    [context, find(db, sessionID), SessionHistory.latestCompaction(db, sessionID)],
-    { concurrency: "unbounded" },
-  )
+  const [value, stored] = yield* Effect.all([context, find(db, sessionID)], { concurrency: "unbounded" })
   if (!stored) {
     const generation = yield* SystemContext.initialize(value)
-    const baselineSeq = yield* insert(db, sessionID, generation)
-    return { baseline: generation.baseline, baselineSeq }
+    const baselineSeq = yield* insert(db, sessionID, location, agent, generation)
+    return { baseline: generation.baseline, baselineSeq, revision: 0 }
   }
 
   const snapshot = yield* Schema.decodeUnknownEffect(SystemContext.Snapshot)(stored.snapshot).pipe(
     Effect.mapError((error) => new ContextSnapshotDecodeError({ sessionID, details: String(error) })),
   )
-  const replacementSeq = compaction !== undefined && compaction.seq > stored.baseline_seq ? compaction.seq : undefined
-  const result = replacementSeq
-    ? yield* SystemContext.replace(value, snapshot)
-    : yield* SystemContext.reconcile(value, snapshot)
+  const replacingAgent = stored.agent !== agent
+  const result =
+    stored.replacement_seq === null && !replacingAgent
+      ? yield* SystemContext.reconcile(value, snapshot)
+      : yield* SystemContext.replace(value, snapshot)
+  if (result._tag === "ReplacementBlocked" && replacingAgent) {
+    yield* fence(db, sessionID, agent, stored.revision)
+    return yield* new AgentReplacementBlocked({ sessionID, previous: stored.agent, current: agent })
+  }
   if (result._tag === "Unchanged" || result._tag === "ReplacementBlocked") {
-    return { baseline: stored.baseline, baselineSeq: stored.baseline_seq }
+    yield* fence(db, sessionID, agent, stored.revision)
+    return { baseline: stored.baseline, baselineSeq: stored.baseline_seq, revision: stored.revision }
   }
   if (result._tag === "ReplacementReady") {
-    const baselineSeq = replacementSeq ?? (yield* SessionInput.latestSeq(db, sessionID))
-    yield* replace(db, sessionID, baselineSeq, result.generation)
-    return { baseline: result.generation.baseline, baselineSeq }
+    const replacementSeq = stored.replacement_seq ?? (yield* SessionInput.latestSeq(db, sessionID))
+    yield* replace(db, sessionID, agent, stored.revision, replacementSeq, result.generation)
+    return { baseline: result.generation.baseline, baselineSeq: replacementSeq, revision: stored.revision + 1 }
   }
 
   yield* events.publish(
     SessionEvent.ContextUpdated,
     { sessionID, messageID: SessionMessageID.ID.create(), timestamp: yield* DateTime.now, text: result.text },
-    { commit: () => advance(db, sessionID, result.snapshot).pipe(Effect.orDie) },
+    { commit: () => advance(db, sessionID, stored.revision, result.snapshot).pipe(Effect.orDie) },
   )
-  return { baseline: stored.baseline, baselineSeq: stored.baseline_seq }
+  return { baseline: stored.baseline, baselineSeq: stored.baseline_seq, revision: stored.revision + 1 }
 })
 
 const initializeOnce = Effect.fnUntraced(function* (
   db: DatabaseService,
   context: Effect.Effect<SystemContext.SystemContext>,
   sessionID: SessionSchema.ID,
+  location: Location.Ref,
+  agent: AgentV2.ID,
 ) {
   if (yield* exists(db, sessionID)) return
   const generation = yield* context.pipe(Effect.flatMap(SystemContext.initialize))
-  const baselineSeq = yield* insert(db, sessionID, generation)
-  return { baseline: generation.baseline, baselineSeq }
+  const baselineSeq = yield* insert(db, sessionID, location, agent, generation)
+  return { baseline: generation.baseline, baselineSeq, revision: 0 }
 })
 
 const exists = Effect.fn("SessionContextEpoch.exists")(function* (db: DatabaseService, sessionID: SessionSchema.ID) {
@@ -108,6 +142,39 @@ const find = Effect.fn("SessionContextEpoch.find")(function* (db: DatabaseServic
     .pipe(Effect.orDie)
 })
 
+const requireAgentSelection = Effect.fnUntraced(function* (
+  db: DatabaseService,
+  sessionID: SessionSchema.ID,
+  agent: AgentV2.ID,
+) {
+  const selected = yield* db
+    .select({ agent: SessionTable.agent })
+    .from(SessionTable)
+    .where(eq(SessionTable.id, sessionID))
+    .get()
+    .pipe(Effect.orDie)
+  if (!selected || (selected.agent !== null && selected.agent !== agent)) return yield* Effect.die(new AgentMismatch())
+})
+
+export const requestReplacement = Effect.fn("SessionContextEpoch.requestReplacement")(function* (
+  db: DatabaseService,
+  sessionID: SessionSchema.ID,
+  seq: number,
+) {
+  return yield* db
+    .update(SessionContextEpochTable)
+    .set({ replacement_seq: seq, revision: sql`${SessionContextEpochTable.revision} + 1` })
+    .where(
+      and(
+        eq(SessionContextEpochTable.session_id, sessionID),
+        lt(SessionContextEpochTable.baseline_seq, seq),
+        or(isNull(SessionContextEpochTable.replacement_seq), lt(SessionContextEpochTable.replacement_seq, seq)),
+      ),
+    )
+    .run()
+    .pipe(Effect.orDie)
+})
+
 export const reset = Effect.fn("SessionContextEpoch.reset")(function* (
   db: DatabaseService,
   sessionID: SessionSchema.ID,
@@ -122,53 +189,155 @@ export const reset = Effect.fn("SessionContextEpoch.reset")(function* (
 const insert = Effect.fnUntraced(function* (
   db: DatabaseService,
   sessionID: SessionSchema.ID,
+  location: Location.Ref,
+  agent: AgentV2.ID,
   generation: SystemContext.Generation,
 ) {
-  const baselineSeq = yield* SessionInput.latestSeq(db, sessionID)
-  yield* db
-    .insert(SessionContextEpochTable)
-    .values({
-      session_id: sessionID,
-      baseline: generation.baseline,
-      snapshot: generation.snapshot,
-      baseline_seq: baselineSeq,
-    })
-    .run()
+  return yield* db
+    .transaction(
+      () =>
+        Effect.gen(function* () {
+          const placed = yield* db
+            .select({ agent: SessionTable.agent })
+            .from(SessionTable)
+            .where(
+              and(
+                eq(SessionTable.id, sessionID),
+                eq(SessionTable.directory, location.directory),
+                location.workspaceID === undefined
+                  ? isNull(SessionTable.workspace_id)
+                  : eq(SessionTable.workspace_id, location.workspaceID),
+              ),
+            )
+            .get()
+            .pipe(Effect.orDie)
+          if (!placed) return yield* Effect.die(new LocationMismatch())
+          if (placed.agent !== null && placed.agent !== agent) return yield* Effect.die(new AgentMismatch())
+          const baselineSeq = yield* SessionInput.latestSeq(db, sessionID)
+          yield* db
+            .insert(SessionContextEpochTable)
+            .values({
+              session_id: sessionID,
+              baseline: generation.baseline,
+              agent,
+              snapshot: generation.snapshot,
+              baseline_seq: baselineSeq,
+              revision: 0,
+            })
+            .onConflictDoNothing()
+            .returning({ sessionID: SessionContextEpochTable.session_id })
+            .get()
+            .pipe(
+              Effect.orDie,
+              Effect.flatMap((inserted) => (inserted ? Effect.void : Effect.die(new RevisionMismatch()))),
+            )
+          return baselineSeq
+        }),
+      { behavior: "immediate" },
+    )
     .pipe(Effect.orDie)
-  return baselineSeq
 })
 
 const replace = Effect.fnUntraced(function* (
   db: DatabaseService,
   sessionID: SessionSchema.ID,
+  agent: AgentV2.ID,
+  expectedRevision: number,
   baselineSeq: number,
   generation: SystemContext.Generation,
 ) {
-  const updated = yield* db
-    .update(SessionContextEpochTable)
-    .set({
-      baseline: generation.baseline,
-      snapshot: generation.snapshot,
-      baseline_seq: baselineSeq,
-    })
+  yield* db
+    .transaction(
+      () =>
+        Effect.gen(function* () {
+          yield* requireAgentSelection(db, sessionID, agent)
+          const updated = yield* db
+            .update(SessionContextEpochTable)
+            .set({
+              baseline: generation.baseline,
+              agent,
+              snapshot: generation.snapshot,
+              baseline_seq: baselineSeq,
+              replacement_seq: null,
+              revision: expectedRevision + 1,
+            })
+            .where(
+              and(
+                eq(SessionContextEpochTable.session_id, sessionID),
+                eq(SessionContextEpochTable.revision, expectedRevision),
+              ),
+            )
+            .returning({ revision: SessionContextEpochTable.revision })
+            .get()
+            .pipe(Effect.orDie)
+          if (!updated) return yield* Effect.die(new RevisionMismatch())
+        }),
+      { behavior: "immediate" },
+    )
+    .pipe(Effect.orDie)
+})
+
+const fence = Effect.fnUntraced(function* (
+  db: DatabaseService,
+  sessionID: SessionSchema.ID,
+  agent: AgentV2.ID,
+  expectedRevision: number,
+) {
+  const current = yield* db
+    .select({ selected: SessionTable.agent, revision: SessionContextEpochTable.revision })
+    .from(SessionContextEpochTable)
+    .innerJoin(SessionTable, eq(SessionTable.id, SessionContextEpochTable.session_id))
     .where(eq(SessionContextEpochTable.session_id, sessionID))
-    .returning({ sessionID: SessionContextEpochTable.session_id })
     .get()
     .pipe(Effect.orDie)
-  if (!updated) return yield* Effect.die("Context Epoch not found")
+  if (!current || (current.selected !== null && current.selected !== agent))
+    return yield* Effect.die(new AgentMismatch())
+  if (current.revision !== expectedRevision) return yield* Effect.die(new RevisionMismatch())
+})
+
+export const current = Effect.fn("SessionContextEpoch.current")(function* (
+  db: DatabaseService,
+  sessionID: SessionSchema.ID,
+  agent: AgentV2.ID,
+  revision: number,
+) {
+  const value = yield* db
+    .select({
+      agent: SessionContextEpochTable.agent,
+      selected: SessionTable.agent,
+      revision: SessionContextEpochTable.revision,
+    })
+    .from(SessionContextEpochTable)
+    .innerJoin(SessionTable, eq(SessionTable.id, SessionContextEpochTable.session_id))
+    .where(eq(SessionContextEpochTable.session_id, sessionID))
+    .get()
+    .pipe(Effect.orDie)
+  return (
+    value !== undefined &&
+    value.agent === agent &&
+    (value.selected === null || value.selected === agent) &&
+    value.revision === revision
+  )
 })
 
 const advance = Effect.fnUntraced(function* (
   db: DatabaseService,
   sessionID: SessionSchema.ID,
+  expectedRevision: number,
   snapshot: SystemContext.Snapshot,
 ) {
   const updated = yield* db
     .update(SessionContextEpochTable)
-    .set({ snapshot })
-    .where(eq(SessionContextEpochTable.session_id, sessionID))
-    .returning({ sessionID: SessionContextEpochTable.session_id })
+    .set({ snapshot, revision: expectedRevision + 1 })
+    .where(
+      and(
+        eq(SessionContextEpochTable.session_id, sessionID),
+        eq(SessionContextEpochTable.revision, expectedRevision),
+        isNull(SessionContextEpochTable.replacement_seq),
+      ),
+    )
+    .returning({ revision: SessionContextEpochTable.revision })
     .get()
     .pipe(Effect.orDie)
-  if (!updated) return yield* Effect.die("Context Epoch not found")
+  if (!updated) return yield* Effect.die(new RevisionMismatch())
 })

packages/core/src/session/event.ts

@@ -27,13 +27,13 @@ const Base = {
 }
 
 const options = {
-  durable: {
+  sync: {
     aggregate: "sessionID",
     version: 1,
   },
 } as const
 const stepSettlementOptions = {
-  durable: {
+  sync: {
     aggregate: "sessionID",
     version: 2,
   },
@@ -118,6 +118,13 @@ export namespace PromptLifecycle {
   export type Promoted = typeof Promoted.Type
 }
 
+export const InterruptRequested = EventV2.define({
+  type: "session.next.interrupt.requested",
+  ...options,
+  schema: Base,
+})
+export type InterruptRequested = typeof InterruptRequested.Type
+
 export const ContextUpdated = EventV2.define({
   type: "session.next.context.updated",
   ...options,
@@ -449,7 +456,7 @@ export namespace Compaction {
 
   export const Ended = EventV2.define({
     type: "session.next.compaction.ended",
-    durable: { aggregate: "sessionID", version: 2 },
+    sync: { aggregate: "sessionID", version: 2 },
     schema: {
       ...Base,
       messageID: SessionMessageID.ID,
@@ -468,6 +475,7 @@ const DurableDefinitions = [
   Prompted,
   PromptLifecycle.Admitted,
   PromptLifecycle.Promoted,
+  InterruptRequested,
   ContextUpdated,
   Synthetic,
   Shell.Started,

packages/core/src/session/execution.ts

@@ -5,12 +5,12 @@ import { SessionRunner } from "./runner/index"
 import { SessionSchema } from "./schema"
 
 export interface Interface {
-  /** Starts execution while idle or joins the active execution. */
+  /** Explicitly drain one Session, making at least one provider attempt. */
   readonly resume: (sessionID: SessionSchema.ID) => Effect.Effect<void, SessionRunner.RunError>
-  /** Registers newly recorded work. Repeated wakeups may coalesce. */
-  readonly wake: (sessionID: SessionSchema.ID) => Effect.Effect<void>
+  /** Schedule a drain after durable work is recorded. Repeated wakeups may coalesce. */
+  readonly wake: (sessionID: SessionSchema.ID, seq?: number) => Effect.Effect<void, SessionRunner.RunError>
   /** Interrupt active work owned by this process. Idle interruption is a no-op. */
-  readonly interrupt: (sessionID: SessionSchema.ID) => Effect.Effect<void>
+  readonly interrupt: (sessionID: SessionSchema.ID, seq?: number) => Effect.Effect<void>
 }
 
 /** Routes execution from a Session ID to the runner owned by that Session's Location. */

packages/core/src/session/execution/local.ts

@@ -1,10 +1,11 @@
-import { Cause, Effect, Layer } from "effect"
+import { Effect, Layer } from "effect"
 import { LocationServiceMap } from "../../location-layer"
 import { SessionRunCoordinator } from "../run-coordinator"
 import { SessionRunner } from "../runner"
 import { SessionSchema } from "../schema"
 import { SessionStore } from "../store"
 import { SessionExecution } from "../execution"
+import { logFailure } from "../logging"
 
 /** Current-process routing for implicit-local Locations. Future remote placement belongs here. */
 export const layer = Layer.effect(
@@ -12,19 +13,15 @@ export const layer = Layer.effect(
   Effect.gen(function* () {
     const store = yield* SessionStore.Service
     const locations = yield* LocationServiceMap
-    const coordinator = yield* SessionRunCoordinator.make<SessionSchema.ID, SessionRunner.RunError>({
-      drain: Effect.fnUntraced(function* (sessionID: SessionSchema.ID, force) {
+    const coordinator = yield* SessionRunCoordinator.make<SessionSchema.ID, void, SessionRunner.RunError>({
+      drain: Effect.fnUntraced(function* (sessionID: SessionSchema.ID, mode) {
         const session = yield* store.get(sessionID)
         if (!session) return yield* Effect.die(`Session not found: ${sessionID}`)
-        return yield* SessionRunner.Service.use((runner) => runner.run({ sessionID, force })).pipe(
+        return yield* SessionRunner.Service.use((runner) => runner.run({ sessionID, force: mode === "run" })).pipe(
           Effect.provide(locations.get(session.location)),
-          Effect.tapCause((cause) =>
-            Cause.hasInterruptsOnly(cause)
-              ? Effect.void
-              : Effect.logError("Failed to drain Session", cause).pipe(Effect.annotateLogs({ sessionID })),
-          ),
         )
       }),
+      onFailure: (sessionID, cause) => logFailure("Failed to drain Session", sessionID, cause),
     })
 
     return SessionExecution.Service.of({

packages/core/src/session/history.ts

@@ -10,9 +10,9 @@ type DatabaseService = Database.Interface["db"]
 
 const decode = Schema.decodeUnknownEffect(SessionMessage.Message)
 
-export const latestCompaction = Effect.fnUntraced(function* (db: DatabaseService, sessionID: SessionSchema.ID) {
+const latestCompaction = Effect.fnUntraced(function* (db: DatabaseService, sessionID: SessionSchema.ID) {
   return yield* db
-    .select({ seq: SessionMessageTable.seq })
+    .select()
     .from(SessionMessageTable)
     .where(and(eq(SessionMessageTable.session_id, sessionID), eq(SessionMessageTable.type, "compaction")))
     .orderBy(desc(SessionMessageTable.seq))

packages/core/src/session/input.ts

@@ -74,11 +74,11 @@ export const admit = Effect.fn("SessionInput.admit")(function* (
     })
     .pipe(
       Effect.flatMap((event) =>
-        event.durable === undefined
+        event.seq === undefined
           ? Effect.die("Prompt admission event is missing aggregate sequence")
           : Effect.succeed(
               new Admitted({
-                admittedSeq: event.durable.seq,
+                admittedSeq: event.seq,
                 id: input.id,
                 sessionID: input.sessionID,
                 prompt: input.prompt,
@@ -117,6 +117,13 @@ export const projectAdmitted = Effect.fn("SessionInput.projectAdmitted")(functio
     readonly timeCreated: DateTime.Utc
   },
 ) {
+  const message = yield* db
+    .select({ id: SessionMessageTable.id })
+    .from(SessionMessageTable)
+    .where(eq(SessionMessageTable.id, input.id))
+    .get()
+    .pipe(Effect.orDie)
+  if (message) return yield* Effect.die(new LifecycleConflict({ id: input.id }))
   const stored = yield* db
     .insert(SessionInputTable)
     .values({
@@ -201,6 +208,37 @@ const matchesPrompt = (input: Admitted, expected: { readonly sessionID: SessionS
   input.sessionID === expected.sessionID &&
   JSON.stringify(encodePrompt(input.prompt)) === JSON.stringify(encodePrompt(expected.prompt))
 
+export const guardReservedID = Effect.fn("SessionInput.guardReservedID")(function* (
+  db: DatabaseService,
+  event: EventV2.Payload,
+) {
+  if (
+    Schema.is(SessionEvent.PromptLifecycle.Admitted)(event) ||
+    Schema.is(SessionEvent.PromptLifecycle.Promoted)(event)
+  )
+    return
+  const id = reservedID(event)
+  if (id === undefined) return
+  const admitted = yield* db
+    .select({ id: SessionInputTable.id })
+    .from(SessionInputTable)
+    .where(eq(SessionInputTable.id, id))
+    .get()
+    .pipe(Effect.orDie)
+  if (admitted === undefined) return
+  return yield* Effect.die(new LifecycleConflict({ id }))
+})
+
+const reservedID = (event: EventV2.Payload) => {
+  if (Schema.is(SessionEvent.Step.Started)(event)) return event.data.assistantMessageID
+  if (Schema.is(SessionEvent.AgentSwitched)(event)) return event.data.messageID
+  if (Schema.is(SessionEvent.ModelSwitched)(event)) return event.data.messageID
+  if (Schema.is(SessionEvent.Prompted)(event)) return event.data.messageID
+  if (Schema.is(SessionEvent.Synthetic)(event)) return event.data.messageID
+  if (Schema.is(SessionEvent.Shell.Started)(event)) return event.data.messageID
+  if (Schema.is(SessionEvent.Compaction.Started)(event)) return event.data.messageID
+}
+
 export const projectLegacyPrompted = Effect.fn("SessionInput.projectLegacyPrompted")(function* (
   db: DatabaseService,
   input: {

packages/core/src/session/logging.ts

@@ -0,0 +1,8 @@
+import { Cause, Effect } from "effect"
+import { SessionSchema } from "./schema"
+
+export const logFailure = (
+  message: "Failed to drain Session" | "Failed to wake Session",
+  sessionID: SessionSchema.ID,
+  cause: Cause.Cause<unknown>,
+) => Effect.logError(message, cause).pipe(Effect.annotateLogs({ sessionID }))

packages/core/src/session/message-updater.ts

@@ -138,6 +138,7 @@ export function update(adapter: Adapter, event: SessionEvent.Event) {
       },
       "session.next.prompt.admitted": () => Effect.void,
       "session.next.prompt.promoted": () => Effect.void,
+      "session.next.interrupt.requested": () => Effect.void,
       "session.next.context.updated": (event) =>
         adapter.appendMessage(
           new SessionMessage.System({

packages/core/src/session/projector.ts

@@ -115,7 +115,7 @@ function run(db: DatabaseService, event: SessionEvent.Event) {
     const decodeRow = (row: typeof SessionMessageTable.$inferSelect) =>
       decodeMessage({ ...row.data, id: row.id, type: row.type })
     const updateMessage = (message: SessionMessage.Message) => {
-      if (event.durable === undefined) return Effect.die("Durable Session event is missing aggregate sequence")
+      if (event.seq === undefined) return Effect.die("Synchronized Session event is missing aggregate sequence")
       const encoded = encodeMessage(message)
       const { id, type, ...data } = encoded
       return db
@@ -192,7 +192,7 @@ function run(db: DatabaseService, event: SessionEvent.Event) {
 }
 
 function insertMessage(db: DatabaseService, event: SessionEvent.Event, message: SessionMessage.Message) {
-  if (event.durable === undefined) return Effect.die("Durable Session event is missing aggregate sequence")
+  if (event.seq === undefined) return Effect.die("Synchronized Session event is missing aggregate sequence")
   const encoded = encodeMessage(message)
   const { id, type, ...data } = encoded
   return db
@@ -201,7 +201,7 @@ function insertMessage(db: DatabaseService, event: SessionEvent.Event, message:
       id: SessionMessage.ID.make(id),
       session_id: event.data.sessionID,
       type,
-      seq: event.durable.seq,
+      seq: event.seq,
       time_created: DateTime.toEpochMillis(message.time.created),
       data,
     })
@@ -213,6 +213,7 @@ export const layer = Layer.effectDiscard(
   Effect.gen(function* () {
     const events = yield* EventV2.Service
     const { db } = yield* Database.Service
+    yield* events.beforeCommit((event) => SessionInput.guardReservedID(db, event))
     yield* events.project(SessionV1.Event.Created, (event) =>
       Effect.gen(function* () {
         const stored = yield* db
@@ -329,14 +330,19 @@ export const layer = Layer.effectDiscard(
         if (next) yield* applyUsage(db, sessionID, next)
       }),
     )
-    yield* events.project(SessionEvent.AgentSwitched, (event) =>
-      db
+    yield* events.project(SessionEvent.AgentSwitched, (event) => {
+      if (event.seq === undefined) return Effect.die("Synchronized Session event is missing aggregate sequence")
+      return db
         .update(SessionTable)
         .set({ agent: event.data.agent, time_updated: DateTime.toEpochMillis(event.data.timestamp) })
         .where(eq(SessionTable.id, event.data.sessionID))
         .run()
-        .pipe(Effect.orDie, Effect.andThen(run(db, event))),
-    )
+        .pipe(
+          Effect.orDie,
+          Effect.andThen(run(db, event)),
+          Effect.andThen(SessionContextEpoch.requestReplacement(db, event.data.sessionID, event.seq)),
+        )
+    })
     yield* events.project(SessionEvent.ModelSwitched, (event) =>
       Effect.gen(function* () {
         yield* db
@@ -346,6 +352,9 @@ export const layer = Layer.effectDiscard(
           .run()
           .pipe(Effect.orDie)
         yield* run(db, event)
+        if (event.seq === undefined)
+          return yield* Effect.die("Synchronized Session event is missing aggregate sequence")
+        yield* SessionContextEpoch.requestReplacement(db, event.data.sessionID, event.seq)
       }),
     )
     yield* events.project(SessionEvent.Prompted, (event) =>
@@ -359,22 +368,24 @@ export const layer = Layer.effectDiscard(
           .pipe(Effect.orDie)
         if (existing) return yield* Effect.die(new PromptAlreadyProjected())
         yield* run(db, event)
-        if (event.durable === undefined) return yield* Effect.die("Durable Session event is missing aggregate sequence")
+        if (event.seq === undefined)
+          return yield* Effect.die("Synchronized Session event is missing aggregate sequence")
         yield* SessionInput.projectLegacyPrompted(db, {
           id: messageID,
           sessionID: event.data.sessionID,
           prompt: event.data.prompt,
           delivery: event.data.delivery,
           timeCreated: event.data.timestamp,
-          promotedSeq: event.durable.seq,
+          promotedSeq: event.seq,
         })
       }),
     )
     yield* events.project(SessionEvent.PromptLifecycle.Admitted, (event) =>
       Effect.gen(function* () {
-        if (event.durable === undefined) return yield* Effect.die("Durable Session event is missing aggregate sequence")
+        if (event.seq === undefined)
+          return yield* Effect.die("Synchronized Session event is missing aggregate sequence")
         yield* SessionInput.projectAdmitted(db, {
-          admittedSeq: event.durable.seq,
+          admittedSeq: event.seq,
           id: event.data.messageID,
           sessionID: event.data.sessionID,
           prompt: event.data.prompt,
@@ -385,7 +396,8 @@ export const layer = Layer.effectDiscard(
     )
     yield* events.project(SessionEvent.PromptLifecycle.Promoted, (event) =>
       Effect.gen(function* () {
-        if (event.durable === undefined) return yield* Effect.die("Durable Session event is missing aggregate sequence")
+        if (event.seq === undefined)
+          return yield* Effect.die("Synchronized Session event is missing aggregate sequence")
         yield* insertMessage(
           db,
           event,
@@ -394,12 +406,18 @@ export const layer = Layer.effectDiscard(
             sessionID: event.data.sessionID,
             prompt: event.data.prompt,
             timeCreated: event.data.timeCreated,
-            promotedSeq: event.durable.seq,
+            promotedSeq: event.seq,
           }),
         )
       }),
     )
-    yield* events.project(SessionEvent.ContextUpdated, (event) => run(db, event))
+    yield* events.project(SessionEvent.InterruptRequested, () => Effect.void)
+    yield* events.project(SessionEvent.ContextUpdated, (event) => {
+      if (!event.replay || event.seq === undefined) return run(db, event)
+      return run(db, event).pipe(
+        Effect.andThen(SessionContextEpoch.requestReplacement(db, event.data.sessionID, event.seq)),
+      )
+    })
     yield* events.project(SessionEvent.Synthetic, (event) => run(db, event))
     yield* events.project(SessionEvent.Shell.Started, (event) => run(db, event))
     yield* events.project(SessionEvent.Shell.Ended, (event) => run(db, event))
@@ -417,9 +435,15 @@ export const layer = Layer.effectDiscard(
     yield* events.project(SessionEvent.Reasoning.Started, (event) => run(db, event))
     yield* events.project(SessionEvent.Reasoning.Ended, (event) => run(db, event))
     // yield* events.project(SessionEvent.Retried, (event) => run(db, event))
-    yield* events.project(SessionEvent.Compaction.Ended, (event) =>
-      event.durable?.version === 1 ? Effect.void : run(db, event),
-    )
+    yield* events.project(SessionEvent.Compaction.Ended, (event) => {
+      if (event.version === 1) return Effect.void
+      const seq = event.seq
+      if (seq === undefined) return Effect.die("Synchronized Session event is missing aggregate sequence")
+      return Effect.gen(function* () {
+        yield* run(db, event)
+        yield* SessionContextEpoch.requestReplacement(db, event.data.sessionID, seq)
+      })
+    })
   }),
 )
 

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

@@ -1,43 +1,106 @@
 export * as SessionRunCoordinator from "./run-coordinator"
 
-import { Deferred, Effect, Exit, Fiber, FiberSet, Scope } from "effect"
+import { Cause, Context, Deferred, Effect, Exit, Fiber, FiberSet, Layer, Scope } from "effect"
+import { SessionRunner } from "./runner"
+import { logFailure } from "./logging"
+import { SessionSchema } from "./schema"
 
-/** Serializes execution for each key while allowing different keys to run concurrently. */
-export interface Coordinator<Key, E> {
-  /** Starts execution while idle or joins the active execution. */
-  readonly run: (key: Key) => Effect.Effect<void, E>
-  /** Registers one coalesced follow-up after newly recorded work. */
-  readonly wake: (key: Key) => Effect.Effect<void>
-  /** Stops active execution and waits for its cleanup. */
-  readonly interrupt: (key: Key) => Effect.Effect<void>
+export type Mode = "run" | "wake"
+
+/** Why one drain generation should run. Explicit runs dominate advisory wakes when demands coalesce. */
+type Demand = { readonly _tag: "run" } | { readonly _tag: "wake"; readonly seq?: number }
+
+/**
+ * Runs at most one drain chain per key while allowing different keys to drain concurrently.
+ *
+ * For each key:
+ *
+ *   idle --run/wake--> draining --run/wake--> draining + one coalesced rerun --> idle
+ *
+ * `run` is an explicit drain request. It starts a chain or joins the current chain and
+ * upgrades a pending follow-up so the caller receives explicit-run semantics.
+ *
+ * `wake` reports that durable work may now be available. It starts a chain while idle or
+ * requests one coalesced follow-up while draining. Repeated wakes collapse together.
+ *
+ * `interrupt` stops the current ownership chain. Advisory wakes from before the interrupt
+ * boundary are suppressed; advisory wakes after the boundary run after cleanup.
+ */
+export interface Coordinator<Key, A, E> {
+  /** Starts or joins one explicit drain generation. */
+  readonly run: (key: Key) => Effect.Effect<A, E>
+  /** Coalesces one wake-up after durable work is recorded. */
+  readonly wake: (key: Key, seq?: number) => Effect.Effect<void>
+  /** Waits until the current ownership chain settles. */
+  readonly awaitIdle: (key: Key) => Effect.Effect<void, E>
+  /** Interrupts the active ownership chain without automatically draining pending wakes. */
+  readonly interrupt: (key: Key, seq?: number) => Effect.Effect<void>
 }
 
-type Entry<E> = {
-  readonly done: Deferred.Deferred<void, E>
+/** One Session's process-local execution lane: one active demand and at most one coalesced follow-up. */
+type Entry<A, E> = {
+  readonly done: Deferred.Deferred<A, E>
+  readonly settled: Deferred.Deferred<Exit.Exit<A, E>>
+  current: Demand
+  pending?: Demand
+  explicitWaiter?: Deferred.Deferred<A, E>
+  interruptSeq?: number
   owner?: Fiber.Fiber<void, never>
-  pendingWake: boolean
   stopping: boolean
 }
 
-export const make = <Key, E>(options: {
-  readonly drain: (key: Key, force: boolean) => Effect.Effect<void, E>
-}): Effect.Effect<Coordinator<Key, E>, never, Scope.Scope> =>
-  Effect.gen(function* () {
-    const active = new Map<Key, Entry<E>>()
-    const fork = yield* FiberSet.makeRuntime<never, void, never>()
+/** Combines follow-up demand: runs dominate, while wakes retain the newest durable admission sequence. */
+const coalesce = (left: Demand | undefined, right: Demand): Demand => {
+  if (left?._tag === "run" || right._tag === "run") return { _tag: "run" }
+  return { _tag: "wake", seq: maxSeq(left?.seq, right.seq) }
+}
 
-    const makeEntry = (): Entry<E> => ({
-      done: Deferred.makeUnsafe<void, E>(),
-      pendingWake: false,
+const maxSeq = (left: number | undefined, right: number | undefined) => {
+  if (left === undefined) return right
+  if (right === undefined) return left
+  return Math.max(left, right)
+}
+
+/** Constructs a scoped coordinator. Every in-memory transition is synchronous. */
+export const make = <Key, A, E>(options: {
+  readonly drain: (key: Key, mode: Mode) => Effect.Effect<A, E>
+  readonly onFailure?: (key: Key, cause: Cause.Cause<E>) => Effect.Effect<void>
+}): Effect.Effect<Coordinator<Key, A, E>, never, Scope.Scope> =>
+  Effect.gen(function* () {
+    const active = new Map<Key, Entry<A, E>>()
+    const interruptSeq = new Map<Key, number>()
+    const report = yield* FiberSet.makeRuntime<never, void, never>()
+    const fork = yield* FiberSet.makeRuntime<never, void, never>()
+    const shutdown = Deferred.makeUnsafe<void>()
+    let closed = false
+    yield* Effect.addFinalizer(() =>
+      Effect.sync(() => {
+        closed = true
+        Deferred.doneUnsafe(shutdown, Effect.void)
+        active.clear()
+        interruptSeq.clear()
+      }),
+    )
+
+    const makeEntry = (current: Demand, explicitWaiter?: Deferred.Deferred<A, E>): Entry<A, E> => ({
+      done: Deferred.makeUnsafe<A, E>(),
+      settled: Deferred.makeUnsafe<Exit.Exit<A, E>>(),
+      current,
+      explicitWaiter,
       stopping: false,
     })
 
-    const start = (key: Key, entry: Entry<E>, force: boolean, successor = false) => {
+    const start = (key: Key, entry: Entry<A, E>, demand: Demand, successor = false) => {
       const ready = Deferred.makeUnsafe<void>()
+      const drain = Effect.suspend(() => options.drain(key, demand._tag))
+      // Initial work retains immediate-start behavior but cannot run before ownership is published.
+      // Observer-started successors yield once so synchronous drains cannot recurse on the JS stack.
       const owner = fork(
-        (successor ? Effect.yieldNow : Deferred.await(ready)).pipe(
-          Effect.andThen(Effect.suspend(() => options.drain(key, force))),
-          Effect.onExit((exit) => Effect.sync(() => settle(key, entry, exit))),
+        (successor
+          ? Effect.yieldNow.pipe(Effect.andThen(drain))
+          : Deferred.await(ready).pipe(Effect.andThen(drain))
+        ).pipe(
+          Effect.onExit((exit) => Effect.sync(() => settle(key, entry, demand, exit))),
           Effect.exit,
           Effect.asVoid,
         ),
@@ -46,57 +109,176 @@ export const make = <Key, E>(options: {
       if (!successor) Deferred.doneUnsafe(ready, Effect.void)
     }
 
-    const settle = (key: Key, entry: Entry<E>, exit: Exit.Exit<void, E>) => {
-      if (Exit.isSuccess(exit) && !entry.stopping && entry.pendingWake) {
-        entry.pendingWake = false
-        start(key, entry, false, true)
+    const settle = (key: Key, entry: Entry<A, E>, demand: Demand, exit: Exit.Exit<A, E>) => {
+      if (closed) {
+        Deferred.doneUnsafe(entry.done, exit)
+        Deferred.doneUnsafe(entry.settled, Effect.succeed(exit))
+        return
+      }
+      if (demand._tag === "run" && entry.explicitWaiter !== undefined) {
+        Deferred.doneUnsafe(entry.explicitWaiter, exit)
+        entry.explicitWaiter = undefined
+      }
+      if (entry.stopping && demand._tag === "wake" && entry.explicitWaiter !== undefined) {
+        Deferred.doneUnsafe(entry.explicitWaiter, exit)
+        entry.explicitWaiter = undefined
+      }
+      if (active.get(key) !== entry) {
+        Deferred.doneUnsafe(entry.done, exit)
+        Deferred.doneUnsafe(entry.settled, Effect.succeed(exit))
+        return
+      }
+      if (exit._tag === "Success" && !entry.stopping) {
+        if (entry.pending !== undefined) {
+          const pending = entry.pending
+          entry.pending = undefined
+          entry.current = pending
+          start(key, entry, pending, true)
+          return
+        }
+        active.delete(key)
+        Deferred.doneUnsafe(entry.done, exit)
+        Deferred.doneUnsafe(entry.settled, Effect.succeed(exit))
         return
       }
 
-      const successor = entry.pendingWake ? makeEntry() : undefined
+      const successor = entry.pending !== undefined ? makeEntry(entry.pending, entry.explicitWaiter) : undefined
       if (successor === undefined) active.delete(key)
-      else {
-        active.set(key, successor)
-        start(key, successor, false, true)
-      }
+      else active.set(key, successor)
+      if (successor !== undefined) start(key, successor, successor.current, true)
       Deferred.doneUnsafe(entry.done, exit)
+      Deferred.doneUnsafe(entry.settled, Effect.succeed(exit))
+      if (
+        exit._tag === "Failure" &&
+        !(entry.stopping && Cause.hasInterruptsOnly(exit.cause)) &&
+        demand._tag === "wake" &&
+        options.onFailure !== undefined
+      ) {
+        report(Effect.suspend(() => options.onFailure!(key, exit.cause)))
+      }
     }
 
-    const run = (key: Key): Effect.Effect<void, E> =>
-      Effect.uninterruptibleMask((restore) => {
-        const entry = active.get(key)
-        if (entry !== undefined) {
-          if (entry.stopping) return restore(Deferred.await(entry.done).pipe(Effect.andThen(run(key))))
-          return restore(Deferred.await(entry.done))
-        }
-
-        const next = makeEntry()
-        active.set(key, next)
-        start(key, next, true)
-        return restore(Deferred.await(next.done))
-      })
-
-    const wake = (key: Key) =>
+    const wake = (key: Key, seq?: number) =>
       Effect.sync(() => {
+        if (closed) return
+        if (!isAfterInterrupt(key, seq)) return
         const entry = active.get(key)
         if (entry !== undefined) {
-          entry.pendingWake = true
+          if (!acceptsWake(entry, seq)) return
+          entry.pending = coalesce(entry.pending, { _tag: "wake", seq })
           return
         }
 
-        const next = makeEntry()
+        const next = makeEntry({ _tag: "wake", seq })
         active.set(key, next)
-        start(key, next, false)
+        start(key, next, next.current)
       })
 
-    const interrupt = (key: Key): Effect.Effect<void> =>
+    const awaitIdle = (key: Key): Effect.Effect<void, E> =>
+      Effect.gen(function* () {
+        let firstFailure: Cause.Cause<E> | undefined
+        while (!closed) {
+          const entry = active.get(key)
+          if (entry === undefined) break
+          const exit = yield* Effect.raceFirst(
+            Deferred.await(entry.settled),
+            Deferred.await(shutdown).pipe(Effect.as(Exit.void)),
+          )
+          if (closed) break
+          if (exit._tag === "Failure" && firstFailure === undefined) firstFailure = exit.cause
+        }
+        if (firstFailure !== undefined) return yield* Effect.failCause(firstFailure)
+      })
+
+    const interrupt = (key: Key, seq?: number): Effect.Effect<void> =>
       Effect.suspend(() => {
         const entry = active.get(key)
+        const latest = interruptSeq.get(key)
+        if (seq !== undefined && latest !== undefined && seq <= latest)
+          return entry?.stopping && entry.owner !== undefined ? Fiber.interrupt(entry.owner) : Effect.void
+        if (seq !== undefined) interruptSeq.set(key, seq)
         if (entry?.owner === undefined) return Effect.void
+        if (
+          seq !== undefined &&
+          entry.current._tag === "wake" &&
+          entry.current.seq !== undefined &&
+          entry.current.seq > seq
+        )
+          return Effect.void
+        if (entry.stopping) {
+          entry.interruptSeq = maxSeq(entry.interruptSeq, seq)
+          suppressPendingAtOrBefore(entry, seq)
+          return Fiber.interrupt(entry.owner)
+        }
         entry.stopping = true
-        entry.pendingWake = false
+        entry.interruptSeq = seq
+        suppressPendingAtOrBefore(entry, seq)
         return Fiber.interrupt(entry.owner)
       })
 
-    return { run, wake, interrupt }
+    return { run, wake, awaitIdle, interrupt }
+
+    function run(key: Key): Effect.Effect<A, E> {
+      return Effect.uninterruptibleMask((restore) => {
+        if (closed) return Effect.interrupt
+        const entry = active.get(key)
+        if (entry !== undefined) {
+          if (entry.stopping) {
+            return restore(Deferred.await(entry.settled).pipe(Effect.andThen(run(key))))
+          }
+          if (entry.current._tag === "wake") {
+            entry.pending = coalesce(entry.pending, { _tag: "run" })
+            entry.explicitWaiter ??= Deferred.makeUnsafe<A, E>()
+            return restore(awaitRun(entry.explicitWaiter))
+          }
+          return restore(awaitRun(entry.done))
+        }
+
+        const next = makeEntry({ _tag: "run" })
+        active.set(key, next)
+        start(key, next, next.current)
+        return restore(awaitRun(next.done))
+      })
+    }
+
+    function awaitRun(done: Deferred.Deferred<A, E>): Effect.Effect<A, E> {
+      return Effect.raceFirst(Deferred.await(done), Deferred.await(shutdown).pipe(Effect.andThen(Effect.interrupt)))
+    }
+
+    function acceptsWake(entry: Entry<A, E>, seq: number | undefined) {
+      return !entry.stopping || (entry.interruptSeq !== undefined && seq !== undefined && seq > entry.interruptSeq)
+    }
+
+    function isAfterInterrupt(key: Key, seq: number | undefined) {
+      const latest = interruptSeq.get(key)
+      return latest === undefined || (seq !== undefined && seq > latest)
+    }
+
+    function suppressPendingAtOrBefore(entry: Entry<A, E>, seq: number | undefined) {
+      if (
+        entry.pending?._tag === "wake" &&
+        seq !== undefined &&
+        entry.pending.seq !== undefined &&
+        entry.pending.seq > seq
+      )
+        return
+      entry.pending = undefined
+    }
   })
+
+export interface Interface extends Coordinator<SessionSchema.ID, void, SessionRunner.RunError> {}
+
+export class Service extends Context.Service<Service, Interface>()("@opencode/v2/SessionRunCoordinator") {}
+
+export const layer = Layer.effect(
+  Service,
+  SessionRunner.Service.pipe(
+    Effect.flatMap((runner) =>
+      make<SessionSchema.ID, void, SessionRunner.RunError>({
+        drain: (sessionID, mode) => runner.run({ sessionID, force: mode === "run" }),
+        onFailure: (sessionID, cause) => logFailure("Failed to drain Session", sessionID, cause),
+      }),
+    ),
+    Effect.map(Service.of),
+  ),
+)

packages/core/src/session/runner/index.ts

@@ -6,6 +6,7 @@ import { SessionSchema } from "../schema"
 import type { ContextSnapshotDecodeError, MessageDecodeError } from "../error"
 import { SessionRunnerModel } from "./model"
 import type { SystemContext } from "../../system-context/index"
+import type { SessionContextEpoch } from "../context-epoch"
 import type { ToolOutputStore } from "../../tool-output-store"
 
 export type RunError =
@@ -14,6 +15,7 @@ export type RunError =
   | MessageDecodeError
   | ContextSnapshotDecodeError
   | SystemContext.InitializationBlocked
+  | SessionContextEpoch.AgentReplacementBlocked
   | ToolOutputStore.Error
 
 /** Runs one local continuation from already-recorded Session history. */
@@ -21,7 +23,7 @@ export interface Interface {
   /** Drains eligible durable work. Explicit runs perform one provider attempt even when no work is eligible. */
   readonly run: (input: {
     readonly sessionID: SessionSchema.ID
-    readonly force: boolean
+    readonly force?: boolean
   }) => Effect.Effect<void, RunError>
 }
 

packages/core/src/session/runner/llm.ts

@@ -8,7 +8,7 @@ import {
   isContextOverflowFailure,
   type ProviderErrorEvent,
 } from "@opencode-ai/llm"
-import { Cause, DateTime, Effect, FiberSet, Layer, Option, Semaphore, Stream } from "effect"
+import { Cause, DateTime, Effect, FiberSet, Layer, Option, Schema, Semaphore, Stream } from "effect"
 import { AgentV2 } from "../../agent"
 import { Config } from "../../config"
 import { Database } from "../../database/database"
@@ -141,8 +141,8 @@ export const layer = Layer.effect(
       cause.reasons.some((reason) => Cause.isDieReason(reason) && reason.defect instanceof QuestionV2.RejectedError)
 
     type TurnTransition =
-      // Automatic compaction completed; rebuild the request from compacted history.
-      | { readonly _tag: "ContinueAfterCompaction" }
+      // Request preparation observed a concurrent Session change and must restart from durable state.
+      | { readonly _tag: "RebuildPreparedTurn"; readonly promotion?: SessionInput.Delivery }
       // Overflow compaction completed; rebuild once through the path without overflow recovery.
       | { readonly _tag: "ContinueAfterOverflowCompaction" }
 
@@ -152,11 +152,20 @@ export const layer = Layer.effect(
       }
     }
 
-    const continueAfterCompaction = new TurnTransitionError({ _tag: "ContinueAfterCompaction" })
+    const rebuildPreparedTurn = (promotion?: SessionInput.Delivery) =>
+      new TurnTransitionError({ _tag: "RebuildPreparedTurn", promotion })
     const continueAfterOverflowCompaction = new TurnTransitionError({
       _tag: "ContinueAfterOverflowCompaction",
     })
 
+    const retryAgentMismatch = (promotion: SessionInput.Delivery | undefined) =>
+      Effect.catchDefect((defect) =>
+        defect instanceof SessionContextEpoch.AgentMismatch
+          ? Effect.die(rebuildPreparedTurn(promotion))
+          : Effect.die(defect),
+      )
+
+    const sameModel = Schema.toEquivalence(Schema.UndefinedOr(ModelV2.Ref))
     const loadSystemContext = (agent: AgentV2.Selection) =>
       Effect.all([systemContext.load(), skillGuidance.load(agent), referenceGuidance.load()], {
         concurrency: "unbounded",
@@ -172,7 +181,13 @@ export const layer = Layer.effect(
       if (session.location.directory !== location.directory || session.location.workspaceID !== location.workspaceID)
         return yield* Effect.interrupt
       const agent = yield* agents.select(session.agent)
-      const initialized = yield* SessionContextEpoch.initialize(db, loadSystemContext(agent), session.id)
+      const initialized = yield* SessionContextEpoch.initialize(
+        db,
+        loadSystemContext(agent),
+        session.id,
+        session.location,
+        agent.id,
+      ).pipe(retryAgentMismatch(promotion))
       const toolFibers = yield* FiberSet.make<void, ToolOutputStore.Error>()
       let needsContinuation = false
       if (promotion) {
@@ -184,7 +199,18 @@ export const layer = Layer.effect(
         }
       }
       const system =
-        initialized ?? (yield* SessionContextEpoch.prepare(db, events, loadSystemContext(agent), session.id))
+        initialized ??
+        (yield* SessionContextEpoch.prepare(
+          db,
+          events,
+          loadSystemContext(agent),
+          session.id,
+          session.location,
+          agent.id,
+        ).pipe(retryAgentMismatch(undefined)))
+      const current = yield* getSession(sessionID)
+      if ((yield* agents.select(current.agent)).id !== agent.id || !sameModel(current.model, session.model))
+        return yield* Effect.die(rebuildPreparedTurn())
       const model = yield* models.resolve(session)
       const entries = yield* SessionHistory.entriesForRunner(db, session.id, system.baselineSeq)
       const context = entries.map((entry) => entry.message)
@@ -202,7 +228,7 @@ export const layer = Layer.effect(
         toolChoice: isLastStep ? "none" : undefined,
       })
       if (yield* compaction.compactIfNeeded({ sessionID: session.id, entries, model, request }))
-        return yield* Effect.die(continueAfterCompaction)
+        return yield* Effect.die(rebuildPreparedTurn())
       const publisher = createLLMEventPublisher(events, {
         sessionID: session.id,
         agent: agent.id,
@@ -216,6 +242,8 @@ export const layer = Layer.effect(
       const publish = (event: LLMEvent, outputPaths: ReadonlyArray<string> = []) =>
         withPublication(publisher.publish(event, outputPaths))
       let overflowFailure: ProviderErrorEvent | undefined
+      if (!(yield* SessionContextEpoch.current(db, session.id, agent.id, system.revision)))
+        return yield* Effect.die(rebuildPreparedTurn())
       const providerStream = llm.stream(request).pipe(
         Stream.runForEach((event) =>
           Effect.gen(function* () {
@@ -277,7 +305,14 @@ export const layer = Layer.effect(
           const llmFailure = failure instanceof LLMError ? failure : undefined
           if (llmFailure && !publisher.hasProviderError()) {
             yield* withPublication(publisher.failUnsettledTools("Provider did not return a tool result", true))
-            yield* withPublication(publisher.failAssistant(llmFailure.reason.message))
+            yield* withPublication(
+              events.publish(SessionEvent.Step.Failed, {
+                sessionID: session.id,
+                timestamp: yield* DateTime.now,
+                assistantMessageID: yield* publisher.startAssistant(),
+                error: { type: "unknown", message: llmFailure.reason.message },
+              }),
+            )
           }
           if (stream._tag === "Failure" && Cause.hasInterrupts(stream.cause)) yield* FiberSet.clear(toolFibers)
           const settled = yield* restore(awaitToolFibers(toolFibers)).pipe(Effect.exit)
@@ -292,8 +327,6 @@ export const layer = Layer.effect(
           ) {
             yield* FiberSet.clear(toolFibers)
             yield* withPublication(publisher.failUnsettledTools("Tool execution interrupted"))
-            if (publisher.hasActiveAssistant())
-              yield* withPublication(publisher.failAssistant("Provider turn interrupted"))
           }
           if (settled._tag === "Failure" && !Cause.hasInterrupts(settled.cause)) {
             const failure = Cause.squash(settled.cause)
@@ -324,7 +357,7 @@ export const layer = Layer.effect(
             if (defect.transition._tag === "ContinueAfterOverflowCompaction")
               return yield* Effect.die("Post-compaction provider attempt cannot recover another overflow")
             yield* Effect.yieldNow
-            return yield* runAfterOverflowCompaction(sessionID, undefined, step)
+            return yield* runAfterOverflowCompaction(sessionID, defect.transition.promotion, step)
           }),
         ),
       )
@@ -338,7 +371,7 @@ export const layer = Layer.effect(
             yield* Effect.yieldNow
             if (defect.transition._tag === "ContinueAfterOverflowCompaction")
               return yield* runAfterOverflowCompaction(sessionID, undefined, step)
-            return yield* runTurn(sessionID, undefined, step)
+            return yield* runTurn(sessionID, defect.transition.promotion, step)
           }),
         ),
       )
@@ -346,14 +379,14 @@ export const layer = Layer.effect(
 
     const run = Effect.fn("SessionRunner.run")(function* (input: {
       readonly sessionID: SessionSchema.ID
-      readonly force: boolean
+      readonly force?: boolean
     }) {
       const hasSteer = yield* SessionInput.hasPending(db, input.sessionID, "steer")
       const hasQueue = hasSteer ? false : yield* SessionInput.hasPending(db, input.sessionID, "queue")
-      if (!input.force && !hasSteer && !hasQueue) return
+      if (input.force !== true && !hasSteer && !hasQueue) return
       yield* failInterruptedTools(input.sessionID)
       let promotion: SessionInput.Delivery | undefined = hasSteer ? "steer" : hasQueue ? "queue" : undefined
-      let openActivity = input.force || hasSteer || hasQueue
+      let openActivity = input.force === true || hasSteer || hasQueue
       while (openActivity) {
         let needsContinuation = true
         for (let step = 1; needsContinuation; step++) {

packages/core/src/session/runner/model.ts

@@ -5,7 +5,7 @@ import * as AnthropicMessages from "@opencode-ai/llm/protocols/anthropic-message
 import * as OpenAICompatibleChat from "@opencode-ai/llm/protocols/openai-compatible-chat"
 import * as OpenAIResponses from "@opencode-ai/llm/protocols/openai-responses"
 import { Auth, type AnyRoute } from "@opencode-ai/llm/route"
-import { Context, Effect, Layer, Schema } from "effect"
+import { Context, Effect, Layer, Option, Schema } from "effect"
 import { produce } from "immer"
 import { Catalog } from "../../catalog"
 import { Credential } from "../../credential"
@@ -24,23 +24,6 @@ export class ModelNotSelectedError extends Schema.TaggedErrorClass<ModelNotSelec
   },
 ) {}
 
-export class ModelUnavailableError extends Schema.TaggedErrorClass<ModelUnavailableError>()(
-  "SessionRunnerModel.ModelUnavailableError",
-  {
-    providerID: ProviderV2.ID,
-    modelID: ModelV2.ID,
-  },
-) {}
-
-export class VariantUnavailableError extends Schema.TaggedErrorClass<VariantUnavailableError>()(
-  "SessionRunnerModel.VariantUnavailableError",
-  {
-    providerID: ProviderV2.ID,
-    modelID: ModelV2.ID,
-    variant: ModelV2.VariantID,
-  },
-) {}
-
 export class UnsupportedApiError extends Schema.TaggedErrorClass<UnsupportedApiError>()(
   "SessionRunnerModel.UnsupportedApiError",
   {
@@ -50,7 +33,11 @@ export class UnsupportedApiError extends Schema.TaggedErrorClass<UnsupportedApiE
   },
 ) {}
 
-export type Error = ModelNotSelectedError | ModelUnavailableError | VariantUnavailableError | UnsupportedApiError
+export type Error =
+  | Catalog.ProviderNotFoundError
+  | Catalog.ModelNotFoundError
+  | ModelNotSelectedError
+  | UnsupportedApiError
 
 export interface Interface {
   readonly resolve: (session: SessionSchema.Info) => Effect.Effect<Model, Error>
@@ -61,7 +48,7 @@ export class Service extends Context.Service<Service, Interface>()("@opencode/v2
 /** Test or embedding seam for supplying a model resolver directly. */
 export const layerWith = (resolve: Interface["resolve"]) => Layer.succeed(Service, Service.of({ resolve }))
 
-const apiKey = (model: ModelV2.Info, connection?: IntegrationConnection.Info, credential?: Credential.Info) => {
+const apiKey = (model: ModelV2.Info, connection?: IntegrationConnection.Info, credential?: Credential.Stored) => {
   if (credential?.value.type === "key") return Auth.value(credential.value.key)
   if (credential?.value.type === "oauth") return Auth.value(credential.value.access)
   const value = model.request.body.apiKey ?? model.api.settings?.apiKey
@@ -87,27 +74,13 @@ const withDefaults = (model: ModelV2.Info, route: AnyRoute) => {
   })
 }
 
-const withVariant = (
-  model: ModelV2.Info,
-  variantID: ModelV2.VariantID | undefined,
-): Effect.Effect<ModelV2.Info, VariantUnavailableError> => {
+const withVariant = (model: ModelV2.Info, variantID: ModelV2.VariantID | undefined) => {
   const id = variantID === "default" || variantID === undefined ? model.request.variant : variantID
   const variant = model.variants.find((item) => item.id === id)
-  if (!variant && variantID !== undefined && variantID !== "default")
-    return Effect.fail(
-      new VariantUnavailableError({
-        providerID: model.providerID,
-        modelID: model.id,
-        variant: variantID,
-      }),
-    )
-  return Effect.succeed(
-    variant
-      ? produce(model, (draft) => {
-          ModelRequest.assign(draft.request, variant)
-        })
-      : model,
-  )
+  if (!variant) return model
+  return produce(model, (draft) => {
+    ModelRequest.assign(draft.request, variant)
+  })
 }
 
 const apiName = (model: ModelV2.Info) =>
@@ -116,7 +89,7 @@ const apiName = (model: ModelV2.Info) =>
 export const fromCatalogModel = (
   model: ModelV2.Info,
   connection?: IntegrationConnection.Info,
-  credential?: Credential.Info,
+  credential?: Credential.Stored,
 ): Effect.Effect<Model, UnsupportedApiError> => {
   const resolved =
     credential?.value.metadata === undefined
@@ -155,15 +128,8 @@ export const fromCatalogModel = (
   )
 }
 
-export const resolve = (
-  session: SessionSchema.Info,
-  model: ModelV2.Info,
-  connection?: IntegrationConnection.Info,
-  credential?: Credential.Info,
-) =>
-  withVariant(model, session.model?.variant).pipe(
-    Effect.flatMap((model) => fromCatalogModel(model, connection, credential)),
-  )
+export const resolve = (session: SessionSchema.Info, model: ModelV2.Info) =>
+  fromCatalogModel(withVariant(model, session.model?.variant))
 
 export const supported = (model: ModelV2.Info) =>
   model.api.type === "aisdk" &&
@@ -183,24 +149,14 @@ export const locationLayer = Layer.effect(
       resolve: Effect.fn("SessionRunnerModel.resolve")(function* (session) {
         // Location plugins populate and filter the catalog asynchronously during layer startup.
         yield* boot.wait()
-        const defaultModel = session.model ? undefined : yield* catalog.model.default()
         const selected = session.model
-          ? (yield* catalog.model.available()).find(
-              (model) => model.providerID === session.model?.providerID && model.id === session.model.id,
-            )
-          : defaultModel && supported(defaultModel)
-            ? defaultModel
-            : (yield* catalog.model.available()).find(supported)
-        if (!selected && session.model)
-          return yield* new ModelUnavailableError({
-            providerID: session.model.providerID,
-            modelID: session.model.id,
-          })
+          ? yield* catalog.model.get(session.model.providerID, session.model.id)
+          : (Option.getOrUndefined((yield* catalog.model.default()).pipe(Option.filter(supported))) ??
+            (yield* catalog.model.available()).find(supported))
         if (!selected) return yield* new ModelNotSelectedError({ sessionID: session.id })
         const connection = yield* integrations.connection.forIntegration(Integration.ID.make(selected.providerID))
-        return yield* resolve(
-          session,
-          selected,
+        return yield* fromCatalogModel(
+          withVariant(selected, session.model?.variant),
           connection,
           connection?.type === "credential" ? yield* credentials.get(connection.id) : undefined,
         )

packages/core/src/session/runner/publish-llm-event.ts

@@ -65,14 +65,11 @@ export const createLLMEventPublisher = (events: EventV2.Interface, input: Input)
   >()
   const timestamp = DateTime.now
   let assistantMessageID: SessionMessage.ID | undefined
-  let assistantActive = false
-  let assistantFailed = false
   let providerFailed = false
 
   const startAssistant = Effect.fnUntraced(function* () {
     if (assistantMessageID !== undefined) return assistantMessageID
     assistantMessageID = SessionMessage.ID.create()
-    assistantActive = true
     yield* events.publish(SessionEvent.Step.Started, {
       ...input,
       assistantMessageID,
@@ -193,20 +190,6 @@ export const createLLMEventPublisher = (events: EventV2.Interface, input: Input)
     yield* flushFragments()
   })
 
-  const failAssistant = Effect.fnUntraced(function* (message: string) {
-    if (assistantFailed) return
-    yield* flush()
-    const assistantMessageID = yield* startAssistant()
-    assistantActive = false
-    assistantFailed = true
-    yield* events.publish(SessionEvent.Step.Failed, {
-      sessionID: input.sessionID,
-      timestamp: yield* timestamp,
-      assistantMessageID,
-      error: { type: "unknown", message },
-    })
-  })
-
   const failUnsettledTools = Effect.fn("SessionRunner.failUnsettledTools")(function* (
     message: string,
     hostedOnly = false,
@@ -392,7 +375,6 @@ export const createLLMEventPublisher = (events: EventV2.Interface, input: Input)
       }
       case "step-finish":
         yield* flush()
-        assistantActive = false
         yield* events.publish(SessionEvent.Step.Ended, {
           sessionID: input.sessionID,
           timestamp: yield* timestamp,
@@ -406,7 +388,13 @@ export const createLLMEventPublisher = (events: EventV2.Interface, input: Input)
         return
       case "provider-error":
         providerFailed = true
-        yield* failAssistant(event.message)
+        yield* flush()
+        yield* events.publish(SessionEvent.Step.Failed, {
+          sessionID: input.sessionID,
+          timestamp: yield* timestamp,
+          assistantMessageID: yield* startAssistant(),
+          error: { type: "unknown", message: event.message },
+        })
         return
     }
   })
@@ -414,11 +402,10 @@ export const createLLMEventPublisher = (events: EventV2.Interface, input: Input)
   return {
     publish,
     flush,
-    failAssistant,
     failUnsettledTools,
-    hasActiveAssistant: () => assistantActive,
     hasAssistantStarted: () => assistantMessageID !== undefined,
     hasProviderError: () => providerFailed,
+    startAssistant,
     assistantMessageID: assistantMessageIDForTool,
   }
 }

packages/core/src/session/runner/to-llm-message.ts

@@ -82,21 +82,12 @@ const assistant = (message: SessionMessage.Assistant, model: Model) => {
     const result = toolResult(item, sameModel ? (item.provider?.resultMetadata ?? item.provider?.metadata) : undefined)
     return item.provider?.executed === true && result ? [call, result] : [call]
   })
-  const meaningful = content.filter((part) => {
-    if (part.type === "text") return part.text !== ""
-    if (part.type !== "reasoning") return true
-    return part.text !== "" || (part.providerMetadata !== undefined && Object.keys(part.providerMetadata).length > 0)
-  })
   const results = message.content
     .filter((item): item is SessionMessage.AssistantTool => item.type === "tool" && item.provider?.executed !== true)
     .map((item) => toolResult(item, sameModel ? (item.provider?.resultMetadata ?? item.provider?.metadata) : undefined))
     .filter((message) => message !== undefined)
     .map(Message.tool)
-  if (meaningful.length === 0) return results
-  return [
-    Message.make({ id: message.id, role: "assistant", content: meaningful, metadata: message.metadata }),
-    ...results,
-  ]
+  return [Message.make({ id: message.id, role: "assistant", content, metadata: message.metadata }), ...results]
 }
 
 function toLLMMessage(message: SessionMessage.Message, model: Model): Message[] {

packages/core/src/session/sql.ts

@@ -170,6 +170,9 @@ export const SessionContextEpochTable = sqliteTable("session_context_epoch", {
     .primaryKey()
     .references(() => SessionTable.id, { onDelete: "cascade" }),
   baseline: text().notNull(),
+  agent: text().$type<AgentV2.ID>().notNull().default(AgentV2.defaultID),
   snapshot: text({ mode: "json" }).notNull().$type<SystemContext.Snapshot>(),
   baseline_seq: integer().notNull(),
+  replacement_seq: integer(),
+  revision: integer().notNull().default(0),
 })

packages/core/src/skill.ts

@@ -1,7 +1,8 @@
 export * as SkillV2 from "./skill"
 
 import path from "path"
-import { Context, Effect, Layer, Schema, Types } from "effect"
+import { Context, Effect, Layer, Schema } from "effect"
+import { castDraft } from "immer"
 import { AgentV2 } from "./agent"
 import { ConfigMarkdown } from "./config/markdown"
 import { FSUtil } from "./fs-util"
@@ -64,15 +65,16 @@ const Frontmatter = Schema.Struct({
 const decodeFrontmatter = Schema.decodeUnknownOption(Frontmatter)
 
 export type Data = {
-  sources: Types.DeepMutable<Source>[]
+  sources: Source[]
 }
 
-export type Draft = {
+export type Editor = {
   source: (source: Source) => void
   list: () => readonly Source[]
 }
 
-export interface Interface extends State.Transformable<Draft> {
+export interface Interface {
+  readonly transform: State.Interface<Data, Editor>["transform"]
   readonly sources: () => Effect.Effect<Source[]>
   readonly list: () => Effect.Effect<Info[]>
 }
@@ -85,12 +87,12 @@ export const layer = Layer.effect(
     const discovery = yield* SkillDiscovery.Service
     const fs = yield* FSUtil.Service
 
-    const state = State.create<Data, Draft>({
+    const state = State.create<Data, Editor>({
       initial: () => ({ sources: [] }),
-      draft: (draft) => ({
+      editor: (draft) => ({
         source: (source) => {
           if (draft.sources.some((item) => Source.equals(item, source))) return
-          draft.sources.push(source as Types.DeepMutable<Source>)
+          draft.sources.push(castDraft(source))
         },
         list: () => draft.sources as Source[],
       }),
@@ -148,7 +150,6 @@ export const layer = Layer.effect(
 
     return Service.of({
       transform: state.transform,
-      rebuild: state.rebuild,
       sources: Effect.fn("SkillV2.sources")(function* () {
         return state.get().sources
       }),

packages/core/src/state.ts

@@ -1,128 +1,112 @@
 export * as State from "./state"
 
-import { Context, Effect, Scope, Semaphore } from "effect"
+import { Effect, Scope, Semaphore } from "effect"
+import type { Draft, Objectish } from "immer"
 
 /**
- * A replayable transform applied to a draft during rebuild.
+ * A replayable transform applied to an editor during rebuild.
  *
- * Domain drafts expose readable and writable state while preserving concise
- * plugin/config code. Transforms may perform Effects before returning.
+ * Transforms are intentionally synchronous and mutation-shaped: domain editors
+ * hide the draft representation while preserving concise plugin/config code.
  */
-type TransformCallback<DraftApi> = (draft: DraftApi) => Effect.Effect<void> | void
-export type MakeDraft<State, DraftApi> = (state: State) => DraftApi
+export type Transform<Editor> = (editor: Editor) => void
+export type MakeEditor<State extends Objectish, Editor> = (draft: Draft<State>) => Editor
 
-export interface Registration {
-  readonly dispose: Effect.Effect<void>
-}
-
-export type Transform<DraftApi> = (
-  transform: TransformCallback<DraftApi>,
-) => Effect.Effect<Registration, never, Scope.Scope>
-
-export type Rebuild = () => Effect.Effect<void>
-
-export interface Transformable<DraftApi> {
-  readonly transform: Transform<DraftApi>
-  readonly rebuild: Rebuild
-}
-
-const CurrentBatch = Context.Reference<Set<Rebuild> | undefined>("@opencode/State/CurrentBatch", {
-  defaultValue: () => undefined,
-})
-
-export function batch<A, E, R>(effect: Effect.Effect<A, E, R>) {
-  return Effect.gen(function* () {
-    const current = yield* CurrentBatch
-    if (current) return yield* effect
-    const rebuilds = new Set<Rebuild>()
-    const result = yield* effect.pipe(Effect.provideService(CurrentBatch, rebuilds))
-    yield* Effect.forEach(rebuilds, (rebuild) => rebuild(), { discard: true })
-    return result
-  })
-}
-
-export interface Options<State, DraftApi> {
+export interface Options<State extends Objectish, Editor> {
   /** Creates the base value for initial state and every scoped-transform rebuild. */
   readonly initial: () => State
-  /** Wraps mutable state in a domain-specific draft API. */
-  readonly draft: MakeDraft<State, DraftApi>
-  /** Runs after all active transforms and before the rebuilt state becomes visible. */
-  readonly finalize?: (draft: DraftApi) => Effect.Effect<void>
+  /** Wraps the mutable draft in a domain-specific editor. */
+  readonly editor: MakeEditor<State, Editor>
+  /**
+   * Completes every committed edit.
+   *
+   * For rebuilds, this runs after all active transforms have been replayed and
+   * before the rebuilt state becomes visible. For direct updates, this runs
+   * after the current state has already been edited. The optional reason is
+   * caller-defined metadata for exceptional update origins.
+   */
+  readonly finalize?: (editor: Editor, reason?: string) => Effect.Effect<void>
 }
 
-export interface Interface<State, DraftApi> extends Transformable<DraftApi> {
+export interface Interface<State extends Objectish, Editor> {
   readonly get: () => State
   /**
-   * Registers and applies a scoped transform. Closing the owning Scope removes
-   * the transform and rebuilds the materialized state.
+   * Registers a scoped transform slot and returns the slot updater.
+   *
+   * Acquiring the slot has no visible effect until the returned updater is
+   * called. Each updater call replaces that slot's transform, then rebuilds the
+   * materialized state from `initial()` by replaying all active transforms in
+   * registration order. Closing the owning Scope removes the slot and rebuilds.
    */
+  readonly transform: () => Effect.Effect<(transform: Transform<Editor>) => Effect.Effect<void>, never, Scope.Scope>
+  /** Registers and applies a replayable transform in the current Scope. */
+  readonly update: (update: Transform<Editor>) => Effect.Effect<void, never, Scope.Scope>
+  /**
+   * Mutates the current materialized state directly, once.
+   *
+   * This is not replayable transform state: a later rebuild starts again
+   * from `initial()` plus active transforms, so direct edits must be reserved
+   * for current-state adjustments that are intentionally outside the transform
+   * fold.
+   */
+  readonly mutate: (update: (editor: Editor) => Effect.Effect<void>, reason?: string) => Effect.Effect<void>
 }
 
-export function create<State, DraftApi>(options: Options<State, DraftApi>): Interface<State, DraftApi> {
+export function create<State extends Objectish, Editor>(options: Options<State, Editor>): Interface<State, Editor> {
   let state = options.initial()
-  let transforms: { run: TransformCallback<DraftApi> }[] = []
+  let transforms: { update: Transform<Editor> }[] = []
   const semaphore = Semaphore.makeUnsafe(1)
 
-  const commit = Effect.fn("State.commit")(function* (next: State) {
-    const api = options.draft(next)
-    if (options.finalize) yield* options.finalize(api)
+  const commit = Effect.fn("State.commit")(function* (next: State, reason?: string) {
+    const api = options.editor(next as Draft<State>)
+    if (options.finalize) yield* options.finalize(api, reason)
     state = next
   })
 
-  const apply = (transform: TransformCallback<DraftApi>, draft: DraftApi) =>
-    Effect.suspend(() => {
-      const result = transform(draft)
-      return Effect.isEffect(result) ? Effect.asVoid(result).pipe(Effect.orDie) : Effect.void
-    })
-
-  const materialize = Effect.fnUntraced(function* () {
+  const rebuild = Effect.fnUntraced(function* () {
     const next = options.initial()
-    const api = options.draft(next)
-    for (const transform of transforms) yield* apply(transform.run, api).pipe(Effect.withSpan("State.rebuild.update"))
+    const api = options.editor(next as Draft<State>)
+    for (const transform of transforms)
+      yield* Effect.sync(() => transform.update(api)).pipe(Effect.withSpan("State.rebuild.update", {}))
     yield* commit(next)
   })
 
-  const rebuild = () => semaphore.withPermit(materialize())
-
-  const result: Interface<State, DraftApi> = {
+  const result: Interface<State, Editor> = {
     get: () => state,
-    transform: Effect.fn("State.transform")(function* (update) {
+    transform: Effect.fn("State.transform")(function* () {
       const scope = yield* Scope.Scope
       return yield* Effect.uninterruptible(
         Effect.gen(function* () {
-          const transform = { run: update }
-          let active = true
-          const dispose = Effect.uninterruptible(
+          const transform = { update: (_editor: Editor) => {} }
+          transforms = [...transforms, transform]
+          yield* Scope.addFinalizer(
+            scope,
             semaphore.withPermit(
-              Effect.suspend(() => {
-                if (!active) return Effect.void
-                active = false
+              Effect.sync(() => {
                 transforms = transforms.filter((item) => item !== transform)
-                return Effect.gen(function* () {
-                  const batch = yield* CurrentBatch
-                  if (batch) {
-                    batch.add(rebuild)
-                    return
-                  }
-                  yield* materialize()
-                })
-              }),
+              }).pipe(Effect.andThen(rebuild())),
             ),
           )
-          yield* semaphore.withPermit(
-            Effect.sync(() => {
-              transforms = [...transforms, transform]
-            }),
-          )
-          yield* Scope.addFinalizer(scope, dispose)
-          const batch = yield* CurrentBatch
-          if (batch) batch.add(rebuild)
-          else yield* rebuild()
-          return { dispose }
+          return (update: Transform<Editor>) =>
+            Effect.uninterruptible(
+              semaphore.withPermit(
+                Effect.sync(() => {
+                  transform.update = update
+                }).pipe(Effect.andThen(rebuild())),
+              ),
+            )
         }),
       )
     }),
-    rebuild,
+    update: Effect.fn("State.update")(function* (update) {
+      const transform = yield* result.transform()
+      yield* transform(update)
+    }),
+    mutate: Effect.fn("State.mutate")(function* (update, reason) {
+      const api = options.editor(state as Draft<State>)
+      yield* update(api)
+      if (options.finalize) yield* options.finalize(api, reason)
+    }, semaphore.withPermit),
   }
   return result
 }

packages/core/src/tool/application-tools.ts

@@ -1,6 +1,7 @@
 export * as ApplicationTools from "./application-tools"
 
 import { Context, Effect, Layer, Scope } from "effect"
+import { enableMapSet } from "immer"
 import { State } from "../state"
 import { Tool } from "./tool"
 
@@ -8,7 +9,7 @@ type Data = {
   readonly entries: Map<string, Entry>
 }
 
-type Draft = {
+type Editor = {
   readonly set: (name: string, entry: Entry) => void
 }
 
@@ -26,12 +27,14 @@ export interface Interface {
 
 export class Service extends Context.Service<Service, Interface>()("@opencode/ApplicationTools") {}
 
+enableMapSet()
+
 export const layer = Layer.effect(
   Service,
   Effect.gen(function* () {
-    const state = State.create<Data, Draft>({
+    const state = State.create<Data, Editor>({
       initial: () => ({ entries: new Map() }),
-      draft: (draft) => ({
+      editor: (draft) => ({
         set: (name, tool) => {
           draft.entries.set(name, tool)
         },
@@ -44,8 +47,9 @@ export const layer = Layer.effect(
         if (entries.length === 0) return
         yield* Effect.forEach(entries, ([name]) => Tool.validateName(name), { discard: true })
         const registrations = entries.map(([name, tool]) => [name, { identity: {}, tool }] as const)
-        yield* state.transform((draft) => {
-          for (const [name, entry] of registrations) draft.set(name, entry)
+        const transform = yield* state.transform()
+        yield* transform((editor) => {
+          for (const [name, entry] of registrations) editor.set(name, entry)
         })
       }),
       entries: () => state.get().entries,

packages/core/src/tool/http-body.ts

@@ -1,30 +0,0 @@
-import { Effect, Stream } from "effect"
-import { HttpClientResponse } from "effect/unstable/http"
-
-export const collectBoundedResponseBody = (
-  response: HttpClientResponse.HttpClientResponse,
-  maximumBytes: number,
-  tooLarge: () => Error,
-) =>
-  Effect.gen(function* () {
-    const contentLength = response.headers["content-length"]
-    const parsedSize = contentLength ? Number.parseInt(contentLength, 10) : undefined
-    const declaredSize =
-      parsedSize !== undefined && Number.isSafeInteger(parsedSize) && parsedSize >= 0 ? parsedSize : undefined
-    if (declaredSize !== undefined && declaredSize > maximumBytes) return yield* Effect.fail(tooLarge())
-    let body = Buffer.allocUnsafe(Math.min(maximumBytes, declaredSize || 64 * 1024))
-    let size = 0
-    yield* Stream.runForEach(response.stream, (chunk) => {
-      if (chunk.byteLength === 0) return Effect.void
-      if (size + chunk.byteLength > maximumBytes) return Effect.fail(tooLarge())
-      if (size + chunk.byteLength > body.byteLength) {
-        const grown = Buffer.allocUnsafe(Math.min(maximumBytes, Math.max(size + chunk.byteLength, body.byteLength * 2)))
-        body.copy(grown, 0, 0, size)
-        body = grown
-      }
-      body.set(chunk, size)
-      size += chunk.byteLength
-      return Effect.void
-    })
-    return body.subarray(0, size)
-  })

packages/core/src/tool/read-filesystem.ts

@@ -13,61 +13,23 @@ export const MAX_MEDIA_INGEST_BYTES = 20 * 1024 * 1024
 const MAX_LINE_LENGTH = 2_000
 const MAX_LINE_SUFFIX = `... (line truncated to ${MAX_LINE_LENGTH} chars)`
 
-export class BinaryFileError extends Schema.TaggedErrorClass<BinaryFileError>()("ReadTool.BinaryFileError", {
-  resource: Schema.String,
-}) {
-  override get message() {
-    return `Cannot read binary file: ${this.resource}`
+export class BinaryFileError extends Error {
+  constructor(readonly resource: string) {
+    super(`Cannot read binary file: ${resource}`)
+    this.name = "BinaryFileError"
   }
 }
 
-export class MediaIngestLimitError extends Schema.TaggedErrorClass<MediaIngestLimitError>()(
-  "ReadTool.MediaIngestLimitError",
-  {
-    resource: Schema.String,
-    maximumBytes: Schema.Number,
-  },
-) {
-  override get message() {
-    return `Media exceeds ${this.maximumBytes} byte ingestion limit: ${this.resource}`
+export class MediaIngestLimitError extends Error {
+  constructor(
+    readonly resource: string,
+    readonly maximumBytes: number,
+  ) {
+    super(`Media exceeds ${maximumBytes} byte ingestion limit: ${resource}`)
+    this.name = "MediaIngestLimitError"
   }
 }
 
-export class MalformedUtf8Error extends Schema.TaggedErrorClass<MalformedUtf8Error>()("ReadTool.MalformedUtf8Error", {
-  resource: Schema.String,
-}) {
-  override get message() {
-    return `File is not valid UTF-8: ${this.resource}`
-  }
-}
-
-export class OffsetOutOfRangeError extends Schema.TaggedErrorClass<OffsetOutOfRangeError>()(
-  "ReadTool.OffsetOutOfRangeError",
-  { offset: Schema.Number },
-) {
-  override get message() {
-    return `Offset ${this.offset} is out of range`
-  }
-}
-
-export class PathKindError extends Schema.TaggedErrorClass<PathKindError>()("ReadTool.PathKindError", {
-  resource: Schema.String,
-  expected: Schema.Literals(["a file", "a file or directory"]),
-}) {
-  override get message() {
-    return `Path is not ${this.expected}: ${this.resource}`
-  }
-}
-
-export type InspectError = FSUtil.Error | PathKindError
-export type ReadError =
-  | FSUtil.Error
-  | BinaryFileError
-  | MediaIngestLimitError
-  | MalformedUtf8Error
-  | OffsetOutOfRangeError
-  | PathKindError
-
 export const PageInput = Schema.Struct({
   offset: PositiveInt.pipe(Schema.optional),
   limit: PositiveInt.check(Schema.isLessThanOrEqualTo(MAX_READ_LINES)).pipe(Schema.optional),
@@ -90,13 +52,13 @@ export class ListPage extends Schema.Class<ListPage>("ReadTool.ListPage")({
 }) {}
 
 export interface Interface {
-  readonly inspect: (path: AbsolutePath) => Effect.Effect<"file" | "directory", InspectError>
+  readonly inspect: (path: AbsolutePath) => Effect.Effect<"file" | "directory">
   readonly read: (
     path: AbsolutePath,
     resource: string,
     page?: PageInput,
-  ) => Effect.Effect<FileSystem.Content | TextPage, ReadError>
-  readonly list: (path: AbsolutePath, page?: PageInput) => Effect.Effect<ListPage, FSUtil.Error>
+  ) => Effect.Effect<FileSystem.Content | TextPage>
+  readonly list: (path: AbsolutePath, page?: PageInput) => Effect.Effect<ListPage>
 }
 
 export class Service extends Context.Service<Service, Interface>()("@opencode/ReadToolFileSystem") {}
@@ -149,21 +111,11 @@ const binary = (resource: string, bytes: Uint8Array) => {
   }
   return nonPrintable / bytes.length > 0.3
 }
-const decodeUtf8 = (resource: string, decoder: TextDecoder, bytes?: Uint8Array) =>
-  Effect.try({
-    try: () => decoder.decode(bytes, { stream: bytes !== undefined }),
-    catch: (error) => {
-      if (error instanceof TypeError) return new MalformedUtf8Error({ resource })
-      throw error
-    },
-  })
-const decodeChunk = (resource: string, decoder: TextDecoder, bytes: Uint8Array) =>
-  bytes.includes(0) ? Effect.fail(new BinaryFileError({ resource })) : decodeUtf8(resource, decoder, bytes)
 
 export const inspect = Effect.fn("ReadTool.inspect")(function* (fs: FSUtil.Interface, input: string) {
-  const info = yield* fs.stat(input)
+  const info = yield* fs.stat(input).pipe(Effect.orDie)
   const type = info.type === "File" ? "file" : info.type === "Directory" ? "directory" : undefined
-  if (!type) return yield* Effect.fail(new PathKindError({ resource: input, expected: "a file or directory" }))
+  if (!type) return yield* Effect.die(new Error("Path is not a file or directory"))
   return type
 })
 
@@ -173,30 +125,32 @@ export const read = Effect.fn("ReadTool.read")(function* (
   resource: string,
   page: PageInput = {},
 ) {
-  const real = yield* fs.realPath(input)
+  const real = yield* fs.realPath(input).pipe(Effect.orDie)
   return yield* Effect.scoped(
     Effect.gen(function* () {
-      const file = yield* fs.open(real, { flag: "r" })
-      const info = yield* file.stat
-      if (info.type !== "File") return yield* Effect.fail(new PathKindError({ resource, expected: "a file" }))
+      const file = yield* fs.open(real, { flag: "r" }).pipe(Effect.orDie)
+      const info = yield* file.stat.pipe(Effect.orDie)
+      if (info.type !== "File") return yield* Effect.die(new Error("Path is not a file"))
       const first = Option.getOrElse(
-        yield* file.readAlloc(Math.min(64 * 1024, Number(info.size) || 4 * 1024)),
+        yield* file.readAlloc(Math.min(64 * 1024, Number(info.size) || 4 * 1024)).pipe(Effect.orDie),
         () => new Uint8Array(),
       )
       const mime = imageMime(first)
       if (mime) {
         if (info.size > MAX_MEDIA_INGEST_BYTES)
-          return yield* Effect.fail(new MediaIngestLimitError({ resource, maximumBytes: MAX_MEDIA_INGEST_BYTES }))
+          return yield* Effect.die(new MediaIngestLimitError(resource, MAX_MEDIA_INGEST_BYTES))
         const chunks = [first]
         let total = first.length
         while (total <= MAX_MEDIA_INGEST_BYTES) {
-          const chunk = yield* file.readAlloc(Math.min(64 * 1024, MAX_MEDIA_INGEST_BYTES + 1 - total))
+          const chunk = yield* file
+            .readAlloc(Math.min(64 * 1024, MAX_MEDIA_INGEST_BYTES + 1 - total))
+            .pipe(Effect.orDie)
           if (Option.isNone(chunk)) break
           chunks.push(chunk.value)
           total += chunk.value.length
         }
         if (total > MAX_MEDIA_INGEST_BYTES)
-          return yield* Effect.fail(new MediaIngestLimitError({ resource, maximumBytes: MAX_MEDIA_INGEST_BYTES }))
+          return yield* Effect.die(new MediaIngestLimitError(resource, MAX_MEDIA_INGEST_BYTES))
         return {
           uri: pathToFileURL(real).href,
           name: path.basename(real),
@@ -208,19 +162,19 @@ export const read = Effect.fn("ReadTool.read")(function* (
           mime,
         }
       }
-      if (startsWith(first, [0x25, 0x50, 0x44, 0x46]) || extensions.has(path.extname(resource).toLowerCase()))
-        return yield* Effect.fail(new BinaryFileError({ resource }))
+      if (startsWith(first, [0x25, 0x50, 0x44, 0x46]) || binary(resource, first))
+        return yield* Effect.die(new BinaryFileError(resource))
       const paged = info.size > MAX_READ_BYTES || page.offset !== undefined || page.limit !== undefined
       if (!paged) {
-        if (binary(resource, first)) return yield* Effect.fail(new BinaryFileError({ resource }))
         const decoder = new TextDecoder("utf-8", { fatal: true })
-        const text = [yield* decodeUtf8(resource, decoder, first)]
+        const text = [yield* Effect.sync(() => decoder.decode(first, { stream: true }))]
         while (true) {
-          const chunk = yield* file.readAlloc(64 * 1024)
+          const chunk = yield* file.readAlloc(64 * 1024).pipe(Effect.orDie)
           if (Option.isNone(chunk)) break
-          text.push(yield* decodeChunk(resource, decoder, chunk.value))
+          if (chunk.value.includes(0)) return yield* Effect.die(new BinaryFileError(resource))
+          text.push(yield* Effect.sync(() => decoder.decode(chunk.value, { stream: true })))
         }
-        text.push(yield* decodeUtf8(resource, decoder))
+        text.push(yield* Effect.sync(() => decoder.decode()))
         return {
           uri: pathToFileURL(real).href,
           name: path.basename(real),
@@ -237,29 +191,34 @@ export const read = Effect.fn("ReadTool.read")(function* (
       let discard = false
       let line = 1
       let bytes = 0
+      let found = false
+      let truncated = false
       let next: number | undefined
       const append = (input: string) => {
         if (line < offset) {
           line++
-          return true
+          return
         }
         if (lines.length >= limit || bytes >= MAX_READ_BYTES) {
-          next = line
-          return false
+          truncated = true
+          next ??= line++
+          return
         }
+        found = true
         const text = input.length > MAX_LINE_LENGTH ? input.slice(0, MAX_LINE_LENGTH) + MAX_LINE_SUFFIX : input
         const size = Buffer.byteLength(text, "utf-8") + (lines.length > 0 ? 1 : 0)
         if (bytes + size > MAX_READ_BYTES) {
-          next = line
-          return false
+          truncated = true
+          next ??= line++
+          return
         }
         lines.push(text)
         bytes += size
         line++
-        return true
       }
-      const consume = (input: string) => {
-        let text = input
+      const consume = (chunk: Uint8Array) => {
+        if (chunk.includes(0)) throw new BinaryFileError(resource)
+        let text = decoder.decode(chunk, { stream: true })
         while (true) {
           const index = text.indexOf("\n")
           if (index === -1) {
@@ -276,44 +235,25 @@ export const read = Effect.fn("ReadTool.read")(function* (
           pending = ""
           discard = false
           text = text.slice(index + 1)
-          if (!append(current.endsWith("\r") ? current.slice(0, -1) : current)) return false
+          append(current.endsWith("\r") ? current.slice(0, -1) : current)
         }
-        return true
       }
-      const consumeChunk = Effect.fnUntraced(function* (chunk: Uint8Array) {
-        let start = 0
-        while (start < chunk.length) {
-          if (lines.length >= limit || bytes >= MAX_READ_BYTES) {
-            next = line
-            return false
-          }
-          const newline = chunk.indexOf(10, start)
-          const end = newline === -1 ? chunk.length : newline + 1
-          const segment = chunk.subarray(start, end)
-          if (binary(resource, segment)) return yield* Effect.fail(new BinaryFileError({ resource }))
-          if (!consume(yield* decodeUtf8(resource, decoder, segment))) return false
-          start = end
-        }
-        return true
-      })
-      let done = !(yield* consumeChunk(first))
-      while (!done) {
-        const chunk = yield* file.readAlloc(64 * 1024)
+      yield* Effect.sync(() => consume(first))
+      while (true) {
+        const chunk = yield* file.readAlloc(64 * 1024).pipe(Effect.orDie)
         if (Option.isNone(chunk)) break
-        done = !(yield* consumeChunk(chunk.value))
+        yield* Effect.sync(() => consume(chunk.value))
       }
-      if (!done) {
-        const tail = yield* decodeUtf8(resource, decoder)
-        if (!discard) pending += tail
-        if (pending) append(pending.endsWith("\r") ? pending.slice(0, -1) : pending)
-      }
-      if (lines.length === 0 && offset !== 1) return yield* Effect.fail(new OffsetOutOfRangeError({ offset }))
+      const tail = yield* Effect.sync(() => decoder.decode())
+      if (!discard) pending += tail
+      if (pending) append(pending.endsWith("\r") ? pending.slice(0, -1) : pending)
+      if (!found && offset !== 1) return yield* Effect.die(new Error(`Offset ${offset} is out of range`))
       return new TextPage({
         type: "text-page",
         content: lines.join("\n"),
         mime: FSUtil.mimeType(real),
         offset,
-        truncated: next !== undefined,
+        truncated,
         ...(next === undefined ? {} : { next }),
       })
     }),
@@ -321,8 +261,8 @@ export const read = Effect.fn("ReadTool.read")(function* (
 })
 
 export const list = Effect.fn("ReadTool.list")(function* (fs: FSUtil.Interface, input: string, page: PageInput = {}) {
-  const real = yield* fs.realPath(input)
-  const items = yield* fs.readDirectoryEntries(real)
+  const real = yield* fs.realPath(input).pipe(Effect.orDie)
+  const items = yield* fs.readDirectoryEntries(real).pipe(Effect.orDie)
   const offset = page.offset ?? 1
   const limit = Math.min(page.limit ?? MAX_READ_LINES, MAX_READ_LINES)
   const entries = yield* Effect.forEach(

packages/core/src/tool/read.ts

@@ -57,8 +57,8 @@ export const layer = Layer.effectDiscard(
               const selected = path.isAbsolute(input.path) ? path.dirname(absolute) : location.directory
               if (!path.isAbsolute(input.path) && !FSUtil.contains(location.directory, absolute))
                 return yield* Effect.die(new Error("Path escapes the allowed read root"))
-              const real = yield* fs.realPath(absolute)
-              const root = yield* fs.realPath(selected)
+              const real = yield* fs.realPath(absolute).pipe(Effect.orDie)
+              const root = yield* fs.realPath(selected).pipe(Effect.orDie)
               if (!FSUtil.contains(root, real))
                 return yield* Effect.die(new Error("Path escapes the allowed read root"))
               const resource = path.relative(root, real).replaceAll("\\", "/") || "."
@@ -83,7 +83,7 @@ export const layer = Layer.effectDiscard(
                   .pipe(Effect.catchTag("Image.ResizerUnavailableError", () => Effect.succeed(content)))
               }
               if ("encoding" in content && content.encoding === "base64")
-                return yield* Effect.fail(new ReadToolFileSystem.BinaryFileError({ resource }))
+                return yield* Effect.fail(new ReadToolFileSystem.BinaryFileError(resource))
               return content
             }).pipe(
               Effect.mapError((error) => {

packages/core/src/tool/webfetch.ts

@@ -1,12 +1,11 @@
 export * as WebFetchTool from "./webfetch"
 
 import { ToolFailure } from "@opencode-ai/llm"
-import { Duration, Effect, Layer, Schema } from "effect"
+import { Duration, Effect, Layer, Schema, Stream } from "effect"
 import { HttpClient, HttpClientRequest, HttpClientResponse } from "effect/unstable/http"
 import { Parser } from "htmlparser2"
 import TurndownService from "turndown"
 import { PermissionV2 } from "../permission"
-import { collectBoundedResponseBody } from "./http-body"
 import { Tool } from "./tool"
 import { Tools } from "./tools"
 
@@ -87,11 +86,24 @@ const execute = (http: HttpClient.HttpClient, url: string, format: Format, userA
   http.execute(request(url, format, userAgent)).pipe(Effect.flatMap(HttpClientResponse.filterStatusOk))
 
 const collectBody = (response: HttpClientResponse.HttpClientResponse) =>
-  collectBoundedResponseBody(
-    response,
-    MAX_RESPONSE_BYTES,
-    () => new Error(`Response too large (exceeds ${MAX_RESPONSE_BYTES} byte limit)`),
-  )
+  Effect.gen(function* () {
+    const contentLength = response.headers["content-length"]
+    if (contentLength && Number.parseInt(contentLength, 10) > MAX_RESPONSE_BYTES) {
+      return yield* Effect.fail(new Error(`Response too large (exceeds ${MAX_RESPONSE_BYTES} byte limit)`))
+    }
+    const chunks: Uint8Array[] = []
+    let size = 0
+    yield* Stream.runForEach(response.stream, (chunk) =>
+      Effect.gen(function* () {
+        size += chunk.byteLength
+        if (size > MAX_RESPONSE_BYTES)
+          return yield* Effect.fail(new Error(`Response too large (exceeds ${MAX_RESPONSE_BYTES} byte limit)`))
+        chunks.push(chunk)
+        return undefined
+      }),
+    )
+    return Buffer.concat(chunks, size)
+  })
 
 const mimeFrom = (contentType: string) => contentType.split(";", 1)[0]?.trim().toLowerCase() ?? ""
 const isImageAttachment = (mime: string) =>
@@ -159,16 +171,12 @@ export const layer = Layer.effectDiscard(
                   orElse: () => Effect.fail(new Error("Request timed out")),
                 }),
               )
-              const content = new TextDecoder().decode(body)
-              const output = yield* Effect.try({
-                try: () => convert(content, contentType, input.format),
-                catch: (error) => error,
-              })
+              const content = convert(new TextDecoder().decode(body), contentType, input.format)
               return {
                 url: input.url,
                 contentType,
                 format: input.format,
-                output,
+                output: content,
               }
             }).pipe(Effect.mapError(() => new ToolFailure({ message: `Unable to fetch ${input.url}` }))),
         }),

packages/core/src/tool/websearch.ts

@@ -9,7 +9,6 @@ import { PositiveInt } from "../schema"
 import { PermissionV2 } from "../permission"
 import { Tool } from "./tool"
 import { Tools } from "./tools"
-import { collectBoundedResponseBody } from "./http-body"
 import { checksum } from "../util/encode"
 
 export const name = "websearch"
@@ -165,12 +164,10 @@ const callMcp = <F extends Schema.Struct.Fields>(
     )
     return yield* Effect.gen(function* () {
       const response = yield* HttpClient.filterStatusOk(http).execute(request)
-      const body = yield* collectBoundedResponseBody(
-        response,
-        MAX_RESPONSE_BYTES,
-        () => new Error(`${tool} response exceeded ${MAX_RESPONSE_BYTES} bytes`),
-      )
-      return yield* parseResponse(body.toString("utf8"))
+      const body = yield* response.text
+      if (Buffer.byteLength(body, "utf8") > MAX_RESPONSE_BYTES)
+        return yield* Effect.fail(new Error(`${tool} response exceeded ${MAX_RESPONSE_BYTES} bytes`))
+      return yield* parseResponse(body)
     }).pipe(
       Effect.timeoutOrElse({
         duration: Duration.seconds(25),

packages/core/src/v1/session.ts

@@ -502,7 +502,7 @@ export type WithParts = {
 }
 
 const options = {
-  durable: {
+  sync: {
     aggregate: "sessionID",
     version: 1,
   },

packages/core/test/agent.test.ts

@@ -6,7 +6,6 @@ import { AgentPlugin } from "@opencode-ai/core/plugin/agent"
 import { AbsolutePath } from "@opencode-ai/core/schema"
 import { location } from "./fixture/location"
 import { testEffect } from "./lib/effect"
-import { agentHost, host } from "./plugin/host"
 
 const it = testEffect(AgentV2.locationLayer)
 
@@ -24,7 +23,9 @@ describe("AgentV2", () => {
     Effect.gen(function* () {
       const agent = yield* AgentV2.Service
       const id = AgentV2.ID.make("reviewer")
-      yield* agent.transform((editor) =>
+      const transform = yield* agent.transform()
+
+      yield* transform((editor) =>
         editor.update(id, (info) => {
           info.description = "Reviews code"
           info.mode = "subagent"
@@ -40,17 +41,19 @@ describe("AgentV2", () => {
     Effect.gen(function* () {
       const agent = yield* AgentV2.Service
       const id = AgentV2.ID.make("reviewer")
-      let description = "Old description"
-      let hidden = true
-      yield* agent.transform((editor) =>
+      const transform = yield* agent.transform()
+
+      yield* transform((editor) =>
         editor.update(id, (info) => {
-          info.description = description
-          info.hidden = hidden
+          info.description = "Old description"
+          info.hidden = true
+        }),
+      )
+      yield* transform((editor) =>
+        editor.update(id, (info) => {
+          info.description = "New description"
         }),
       )
-      description = "New description"
-      hidden = false
-      yield* agent.rebuild()
 
       expect(yield* agent.get(id)).toMatchObject({ description: "New description", hidden: false })
     }),
@@ -61,7 +64,9 @@ describe("AgentV2", () => {
       const agent = yield* AgentV2.Service
       const id = AgentV2.ID.make("scoped")
       const scope = yield* Scope.make()
-      yield* agent.transform((editor) => editor.update(id, () => {})).pipe(Scope.provide(scope))
+      const transform = yield* agent.transform().pipe(Scope.provide(scope))
+
+      yield* transform((editor) => editor.update(id, () => {}))
       expect(yield* agent.get(id)).toBeDefined()
 
       yield* Scope.close(scope, Exit.void)
@@ -74,7 +79,7 @@ describe("AgentV2", () => {
       const agent = yield* AgentV2.Service
       const id = AgentV2.ID.make("build")
 
-      yield* agent.transform((editor) =>
+      yield* agent.update((editor) =>
         editor.update(id, (info) => {
           info.mode = "primary"
           info.hidden = true
@@ -90,10 +95,10 @@ describe("AgentV2", () => {
       const agent = yield* AgentV2.Service
       const id = AgentV2.ID.make("custom")
 
-      yield* agent.transform((editor) => editor.update(id, () => {}))
+      yield* agent.update((editor) => editor.update(id, () => {}))
       expect(yield* agent.get(id)).toEqual(AgentV2.Info.empty(id))
 
-      yield* agent.transform((editor) => editor.remove(id))
+      yield* agent.update((editor) => editor.remove(id))
       expect(yield* agent.get(id)).toBeUndefined()
     }),
   )
@@ -101,11 +106,11 @@ describe("AgentV2", () => {
   it.effect("does not ambiently opt built-in agents into bash", () =>
     Effect.gen(function* () {
       const agent = yield* AgentV2.Service
-      yield* AgentPlugin.Plugin.effect(
-        host({
-          agent: agentHost(agent),
-          location: location({ directory: AbsolutePath.make("/project") }),
-        }),
+      yield* AgentPlugin.Plugin.effect.pipe(
+        Effect.provideService(
+          Location.Service,
+          Location.Service.of(location({ directory: AbsolutePath.make("/project") })),
+        ),
       )
 
       const agents = yield* agent.all()