fix(ai): harden websocket error contracts

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

@@ -211,11 +211,43 @@ export type StreamItem = Schema.Schema.Type<typeof StreamItem>
 // event-level `error` envelope, so accept all three shapes here.
 // https://www.openresponses.org/specification
 const OpenResponsesErrorPayload = Schema.Struct({
+  type: optionalNull(Schema.String),
   code: optionalNull(Schema.String),
   message: optionalNull(Schema.String),
   param: optionalNull(Schema.String),
 })
 
+const WebSocketErrorHeader = Schema.Union([Schema.String, Schema.Number, Schema.Boolean])
+export const WebSocketErrorEvent = Schema.StructWithRest(
+  Schema.Struct({
+    type: Schema.tag("error"),
+    status: Schema.optional(Schema.Number),
+    status_code: Schema.optional(Schema.Number),
+    code: optionalNull(Schema.String),
+    message: Schema.optional(Schema.String),
+    param: optionalNull(Schema.String),
+    error: optionalNull(OpenResponsesErrorPayload),
+    headers: Schema.optional(Schema.Record(Schema.String, WebSocketErrorHeader)),
+  }),
+  [Schema.Record(Schema.String, Schema.Unknown)],
+)
+const decodeWebSocketErrorEvent = Schema.decodeUnknownEffect(WebSocketErrorEvent)
+
+const decodeKnownErrorEvent = (event: Event) =>
+  decodeWebSocketErrorEvent({
+    ...event,
+    status: typeof event.status === "number" ? event.status : undefined,
+    status_code: typeof event.status_code === "number" ? event.status_code : undefined,
+    headers: ProviderShared.isRecord(event.headers)
+      ? Object.fromEntries(
+          Object.entries(event.headers).filter(
+            (entry): entry is [string, string | number | boolean] =>
+              typeof entry[1] === "string" || typeof entry[1] === "number" || typeof entry[1] === "boolean",
+          ),
+        )
+      : undefined,
+  })
+
 export const Event = Schema.StructWithRest(
   Schema.Struct({
     type: Schema.String,
@@ -240,6 +272,9 @@ export const Event = Schema.StructWithRest(
     message: Schema.optional(Schema.String),
     param: optionalNull(Schema.String),
     error: optionalNull(OpenResponsesErrorPayload),
+    status: Schema.optional(Schema.Unknown),
+    status_code: Schema.optional(Schema.Unknown),
+    headers: Schema.optional(Schema.Unknown),
   }),
   [Schema.Record(Schema.String, Schema.Unknown)],
 )
@@ -632,9 +667,9 @@ export type StepResult = readonly [ParserState, ReadonlyArray<LLMEvent>]
 const NO_EVENTS: StepResult["1"] = []
 
 // `response.completed` / `response.incomplete` are clean finishes that emit a
-// `finish` event; `response.failed` is a hard failure. All three end the stream,
+// `finish` event; `response.failed` and `error` are hard failures. All four end
-// so keep this set aligned with `step` and the protocol's terminal predicate.
+// the stream, so keep this set aligned with `step` and the protocol's terminal predicate.
-const TERMINAL_TYPES = new Set(["response.completed", "response.incomplete", "response.failed"])
+const TERMINAL_TYPES = new Set(["error", "response.completed", "response.incomplete", "response.failed"])
 export const terminal = (event: Event) => TERMINAL_TYPES.has(event.type)
 
 const onOutputTextDelta = (state: ParserState, event: Event, id: string): StepResult => {
@@ -969,10 +1004,16 @@ const providerErrorMessage = (event: Event, fallback: string): string => {
 const providerError = (state: ParserState, event: Event, fallback: string) => {
   const code = event.code || event.error?.code || event.response?.error?.code || undefined
   const message = providerErrorMessage(event, fallback)
+  const status =
+    typeof event.status === "number"
+      ? event.status
+      : typeof event.status_code === "number"
+        ? event.status_code
+        : undefined
   return new AIError({
     module: state.id,
     method: "stream",
-    reason: classifyProviderFailure({ message, code }),
+    reason: classifyProviderFailure({ message, code, status }),
   })
 }
 
@@ -1015,7 +1056,11 @@ export const step = (state: ParserState, event: Event) => {
   if (event.type === "response.completed" || event.type === "response.incomplete")
     return Effect.succeed(onResponseFinish(state, event))
   if (event.type === "response.failed") return providerError(state, event, `${state.name} response failed`)
-  if (event.type === "error") return providerError(state, event, `${state.name} stream error`)
+  if (event.type === "error")
+    return decodeKnownErrorEvent(event).pipe(
+      Effect.mapError(() => ProviderShared.eventError(state.id, `${state.name} returned a malformed error event`)),
+      Effect.flatMap(() => providerError(state, event, `${state.name} stream error`)),
+    )
   return Effect.succeed<StepResult>([state, NO_EVENTS])
 }
 

packages/ai/src/provider-error.ts

@@ -67,6 +67,7 @@ const SERVER_CODES = new Set([
   "overloaded_error",
   "server_error",
   "server_is_overloaded",
+  "slow_down",
   "serviceunavailableexception",
 ])
 const INVALID_REQUEST_CODES = new Set(["invalid_prompt", "invalid_request_error", "validationexception"])

packages/ai/src/route/transport/websocket.ts

@@ -29,14 +29,45 @@ export class Service extends Context.Service<Service, Interface>()("@opencode/AI
 const transportError = (
   method: string,
   message: string,
-  input: { readonly url?: string; readonly kind?: string } = {},
+  input: {
+    readonly url?: string
+    readonly kind?: string
+    readonly phase?: TransportReason["phase"]
+    readonly delivery?: TransportReason["delivery"]
+  } = {},
 ) =>
   new AIError({
     module: "WebSocketExecutor",
     method,
-    reason: new TransportReason({ message, url: input.url, kind: input.kind }),
+    reason: new TransportReason({
+      message,
+      url: input.url,
+      kind: input.kind,
+      phase: input.phase,
+      delivery: input.delivery,
+    }),
   })
 
+const annotateTransportError = (
+  error: AIError,
+  input: { readonly phase: TransportReason["phase"]; readonly delivery: TransportReason["delivery"] },
+) =>
+  error.reason._tag === "Transport"
+    ? new AIError({
+        module: error.module,
+        method: error.method,
+        reason: new TransportReason({
+          message: error.reason.message,
+          kind: error.reason.kind,
+          url: error.reason.url,
+          http: error.reason.http,
+          phase: input.phase,
+          delivery: input.delivery,
+          recovery: error.reason.recovery,
+        }),
+      })
+    : error
+
 const eventMessage = (event: Event) => {
   if ("message" in event && typeof event.message === "string") return event.message
   return event.type
@@ -56,6 +87,8 @@ const waitOpen = (ws: globalThis.WebSocket, input: WebSocketRequest) => {
       transportError("open", `WebSocket closed before opening (state ${ws.readyState})`, {
         url: input.url,
         kind: "open",
+        phase: "connect",
+        delivery: "not-sent",
       }),
     )
   }
@@ -79,7 +112,12 @@ const waitOpen = (ws: globalThis.WebSocket, input: WebSocketRequest) => {
       cleanup()
       resume(
         Effect.fail(
-          transportError("open", `Failed to open WebSocket: ${eventMessage(event)}`, { url: input.url, kind: "open" }),
+          transportError("open", `Failed to open WebSocket: ${eventMessage(event)}`, {
+            url: input.url,
+            kind: "open",
+            phase: "connect",
+            delivery: "not-sent",
+          }),
         ),
       )
     }
@@ -90,6 +128,8 @@ const waitOpen = (ws: globalThis.WebSocket, input: WebSocketRequest) => {
           transportError("open", `WebSocket closed before opening with code ${event.code}`, {
             url: input.url,
             kind: "open",
+            phase: "connect",
+            delivery: "not-sent",
           }),
         ),
       )
@@ -119,6 +159,8 @@ const webSocketUrl = (value: string) =>
       transportError("prepare", error instanceof Error ? error.message : "Invalid WebSocket URL", {
         url: value,
         kind: "websocket",
+        phase: "prepare",
+        delivery: "not-sent",
       }),
   })
 
@@ -130,6 +172,8 @@ export const open = (input: WebSocketRequest) =>
       transportError("open", error instanceof Error ? error.message : "Failed to construct WebSocket", {
         url: input.url,
         kind: "open",
+        phase: "connect",
+        delivery: "not-sent",
       }),
   }).pipe(Effect.flatMap((ws) => fromWebSocket(ws, input)))
 
@@ -150,7 +194,11 @@ export const fromWebSocket = (
       Queue.failCauseUnsafe(
         messages,
         Cause.fail(
-          transportError("message", "Unsupported WebSocket message payload", { url: input.url, kind: "message" }),
+          transportError("message", "Unsupported WebSocket message payload", {
+            url: input.url,
+            kind: "message",
+            phase: "receive",
+          }),
         ),
       )
     }
@@ -158,16 +206,23 @@ export const fromWebSocket = (
       Queue.failCauseUnsafe(
         messages,
         Cause.fail(
-          transportError("message", `WebSocket error: ${eventMessage(event)}`, { url: input.url, kind: "message" }),
+          transportError("message", `WebSocket error: ${eventMessage(event)}`, {
+            url: input.url,
+            kind: "message",
+            phase: "receive",
+          }),
         ),
       )
     }
     const onClose = (event: CloseEvent) => {
-      if (event.code === 1000 || event.code === 1005) return Queue.endUnsafe(messages)
       Queue.failCauseUnsafe(
         messages,
         Cause.fail(
-          transportError("message", `WebSocket closed with code ${event.code}`, { url: input.url, kind: "close" }),
+          transportError("message", `WebSocket closed with code ${event.code}`, {
+            url: input.url,
+            kind: "close",
+            phase: "close",
+          }),
         ),
       )
     }
@@ -189,6 +244,8 @@ export const fromWebSocket = (
             transportError("sendText", error instanceof Error ? error.message : "Failed to send WebSocket message", {
               url: input.url,
               kind: "write",
+              phase: "send",
+              delivery: "not-sent",
             }),
         }),
       messages: Stream.fromQueue(messages),
@@ -244,6 +301,8 @@ export const json = <Body, Message>(input: JsonInput<Body, Message>): JsonTransp
         transportError("json", "WebSocket JSON transport requires WebSocketExecutor.Service", {
           url: prepared.url,
           kind: "websocket",
+          phase: "prepare",
+          delivery: "not-sent",
         }),
       )
     }
@@ -251,11 +310,27 @@ export const json = <Body, Message>(input: JsonInput<Body, Message>): JsonTransp
     return Stream.unwrap(
       Effect.gen(function* () {
         const connection = yield* Effect.acquireRelease(
-          webSocket.open({ url: prepared.url, headers: prepared.headers }),
+          webSocket
+            .open({ url: prepared.url, headers: prepared.headers })
+            .pipe(
+              Effect.mapError((error) => annotateTransportError(error, { phase: "connect", delivery: "not-sent" })),
+            ),
           (connection) => connection.close,
         )
         yield* connection.sendText(prepared.message)
-        return connection.messages.pipe(Stream.map((message) => messageText(message, decoder)))
+        let observed = false
+        return connection.messages.pipe(
+          Stream.map((message) => {
+            observed = true
+            return messageText(message, decoder)
+          }),
+          Stream.mapError((error) =>
+            annotateTransportError(error, {
+              phase: error.reason._tag === "Transport" && error.reason.phase === "close" ? "close" : "receive",
+              delivery: observed ? "accepted" : "ambiguous",
+            }),
+          ),
+        )
       }),
     )
   },

packages/ai/src/schema/errors.ts

@@ -98,6 +98,13 @@ export class TransportReason extends Schema.Class<TransportReason>("AI.Error.Tra
   kind: Schema.optional(Schema.String),
   url: Schema.optional(Schema.String),
   http: Schema.optional(HttpContext),
+  phase: Schema.optional(
+    Schema.Literals(["prepare", "queue", "connect", "send", "receive", "decode", "complete", "fallback", "close"]),
+  ),
+  delivery: Schema.optional(Schema.Literals(["not-sent", "rejected", "ambiguous", "accepted"])),
+  recovery: Schema.optional(
+    Schema.Literals(["retry-connect", "retry-full", "rotate-and-retry-full", "fallback-http", "fail"]),
+  ),
 }) {}
 
 export class InvalidProviderOutputReason extends Schema.Class<InvalidProviderOutputReason>(

packages/ai/test/provider-error.test.ts

@@ -69,10 +69,10 @@ describe("provider error classification", () => {
 
   test("classifies V1 overloaded provider codes", () => {
     expect(
-      ['{"code":"resource_exhausted"}', '{"code":"service_unavailable"}'].map(
+      ['{"code":"resource_exhausted"}', '{"code":"service_unavailable"}', '{"code":"slow_down"}'].map(
         (message) => classifyProviderFailure({ message })._tag,
       ),
-    ).toEqual(["ProviderInternal", "ProviderInternal"])
+    ).toEqual(["ProviderInternal", "ProviderInternal", "ProviderInternal"])
   })
 
   test("classifies transient client statuses as provider internal", () => {

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

@@ -11,6 +11,7 @@ import {
   ToolCallPart,
   ToolDefinition,
   ToolResultPart,
+  TransportReason,
   Usage,
 } from "../../src"
 import { Auth, LLMClient, RequestExecutor, WebSocketExecutor } from "../../src/route"
@@ -288,6 +289,114 @@ describe("OpenAI Responses route", () => {
     }),
   )
 
+  it.effect("terminates WebSocket control events without waiting for the socket to close", () =>
+    Effect.gen(function* () {
+      const events = [
+        { type: "error", error: { code: "slow_down", message: "Try later" } },
+        {
+          type: "error",
+          status_code: 429,
+          message: "Rate limited",
+          headers: { "retry-after": 1, "x-request-id": "request", cached: false, invalid: [] },
+        },
+        {
+          type: "response.failed",
+          response: { error: { code: "server_error", message: "Unavailable" } },
+        },
+        { type: "error", status: "not-a-status", message: "Malformed status" },
+      ]
+
+      const errors = yield* Effect.forEach(events, (event) =>
+        LLMClient.generate(
+          LLM.request({
+            model: OpenAI.configure({ baseURL: "https://api.openai.test/v1/", apiKey: "test" }).responsesWebSocket(
+              "gpt-4.1-mini",
+            ),
+            prompt: "Say hello.",
+          }),
+        ).pipe(
+          Effect.provide(
+            LLMClient.layer.pipe(
+              Layer.provide(
+                Layer.mergeAll(
+                  Layer.succeed(
+                    RequestExecutor.Service,
+                    RequestExecutor.Service.of({ execute: () => Effect.die("unexpected HTTP request") }),
+                  ),
+                  Layer.succeed(
+                    WebSocketExecutor.Service,
+                    WebSocketExecutor.Service.of({
+                      open: () =>
+                        Effect.succeed({
+                          sendText: () => Effect.void,
+                          messages: Stream.make(ProviderShared.encodeJson(event)).pipe(Stream.concat(Stream.never)),
+                          close: Effect.void,
+                        }),
+                    }),
+                  ),
+                ),
+              ),
+            ),
+          ),
+          Effect.flip,
+        ),
+      )
+
+      expect(errors.map((error) => error.reason._tag)).toEqual([
+        "ProviderInternal",
+        "RateLimit",
+        "ProviderInternal",
+        "UnknownProvider",
+      ])
+    }),
+  )
+
+  it.effect("marks post-send WebSocket failures with delivery state", () =>
+    Effect.gen(function* () {
+      const failure = new AIError({
+        module: "test",
+        method: "receive",
+        reason: new TransportReason({ message: "socket closed", phase: "close" }),
+      })
+      const streams = [
+        Stream.fail(failure),
+        Stream.make(ProviderShared.encodeJson({ type: "response.created" })).pipe(Stream.concat(Stream.fail(failure))),
+      ]
+      const deps = Layer.mergeAll(
+        Layer.succeed(
+          RequestExecutor.Service,
+          RequestExecutor.Service.of({ execute: () => Effect.die("unexpected HTTP request") }),
+        ),
+        Layer.succeed(
+          WebSocketExecutor.Service,
+          WebSocketExecutor.Service.of({
+            open: () =>
+              Effect.succeed({
+                sendText: () => Effect.void,
+                messages: streams.shift() ?? Stream.die("unexpected WebSocket open"),
+                close: Effect.void,
+              }),
+          }),
+        ),
+      )
+      const model = OpenAI.configure({ baseURL: "https://api.openai.test/v1/", apiKey: "test" }).responsesWebSocket(
+        "gpt-4.1-mini",
+      )
+
+      const errors = yield* Effect.forEach(["first", "second"], (prompt) =>
+        LLMClient.generate(LLM.request({ model, prompt })).pipe(
+          Effect.provide(LLMClient.layer.pipe(Layer.provide(deps))),
+          Effect.flip,
+        ),
+      )
+
+      expect(errors.map((error) => error.reason)).toEqual([
+        expect.objectContaining({ _tag: "Transport", phase: "close", delivery: "ambiguous" }),
+        expect.objectContaining({ _tag: "Transport", phase: "close", delivery: "accepted" }),
+      ])
+    }),
+  )
+
   it.effect("fails immediately when WebSocket is already closed", () =>
     Effect.gen(function* () {
       const error = yield* WebSocketExecutor.fromWebSocket(
@@ -297,6 +406,7 @@ describe("OpenAI Responses route", () => {
       ).pipe(Effect.flip)
 
       expect(error.message).toContain("closed before opening")
+      expect(error.reason).toMatchObject({ _tag: "Transport", phase: "connect", delivery: "not-sent" })
     }),
   )
 

packages/ai/test/schema.test.ts

@@ -11,6 +11,7 @@ import {
   LanguageModel,
   ModelID,
   ProviderID,
+  TransportReason,
   Usage,
 } from "../src/schema"
 import { ProviderShared } from "../src/protocols/shared"
@@ -108,3 +109,21 @@ test("AI errors expose the shared runtime tag", async () => {
     await Effect.runPromise(Effect.fail(error).pipe(Effect.catchTag("AI.Error", () => Effect.succeed("caught")))),
   ).toBe("caught")
 })
+
+test("transport errors serialize execution facts", () => {
+  const reason = new TransportReason({
+    message: "connection closed",
+    phase: "receive",
+    delivery: "ambiguous",
+    recovery: "fail",
+  })
+
+  expect(Schema.encodeSync(TransportReason)(reason)).toEqual({
+    _tag: "Transport",
+    message: "connection closed",
+    phase: "receive",
+    delivery: "ambiguous",
+    recovery: "fail",
+  })
+  expect(Schema.decodeUnknownSync(TransportReason)(Schema.encodeSync(TransportReason)(reason))).toEqual(reason)
+})

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

@@ -420,6 +420,7 @@ export type Endpoint5_26Output =
           readonly data: {
             readonly sessionID: Session.ID
             readonly delta: { readonly [x: string]: (string & Brand.Brand<"Instruction.Hash">) | "removed" }
+            readonly text?: string | undefined
           }
         }
       | {

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

@@ -676,7 +676,7 @@ export type SessionInstructionsUpdated = {
   type: "session.instructions.updated"
   durable: { aggregateID: string; seq: number; version: 2 }
   location?: LocationRef
-  data: { sessionID: string; delta: { [x: string]: string | "removed" } }
+  data: { sessionID: string; delta: { [x: string]: string | "removed" }; text?: string }
 }
 
 export type SessionSynthetic = {

packages/core/src/file-mutation.ts

@@ -1,8 +1,7 @@
 export * as FileMutation from "./file-mutation"
 
 import { makeLocationNode } from "@opencode-ai/util/effect/app-node"
-import { Context, Effect, Layer, Schema } from "effect"
+import { Context, Effect, Layer } from "effect"
-import { dirname } from "path"
 import { KeyedMutex } from "./effect/keyed-mutex"
 import { FSUtil } from "@opencode-ai/util/fs-util"
 import { Bom } from "@opencode-ai/util/bom"
@@ -22,22 +21,6 @@ export interface TextWriteInput {
   readonly content: string
 }
 
-export interface ConditionalWriteInput extends WriteInput {
-  readonly expected: Uint8Array
-}
-
-export interface RemoveInput {
-  readonly target: Target
-}
-
-export class StaleContentError extends Schema.TaggedErrorClass<StaleContentError>()("FileMutation.StaleContentError", {
-  path: Schema.String,
-}) {}
-
-export class TargetExistsError extends Schema.TaggedErrorClass<TargetExistsError>()("FileMutation.TargetExistsError", {
-  path: Schema.String,
-}) {}
-
 export interface WriteResult {
   readonly operation: "write"
   readonly target: string
@@ -45,24 +28,10 @@ export interface WriteResult {
   readonly existed: boolean
 }
 
-export interface RemoveResult {
-  readonly operation: "remove"
-  readonly target: string
-  readonly resource: string
-  readonly existed: boolean
-}
-
 export interface Interface {
-  /** Create without replacing an existing target. */
-  readonly create: (input: WriteInput) => Effect.Effect<WriteResult, TargetExistsError | FSUtil.Error>
   readonly write: (input: WriteInput) => Effect.Effect<WriteResult, FSUtil.Error>
   /** Write text while retaining an existing UTF-8 BOM and emitting at most one BOM. */
   readonly writeTextPreservingBom: (input: TextWriteInput) => Effect.Effect<WriteResult, FSUtil.Error>
-  /** Commit only if an existing target still has the expected bytes. */
-  readonly writeIfUnchanged: (
-    input: ConditionalWriteInput,
-  ) => Effect.Effect<WriteResult, StaleContentError | FSUtil.Error>
-  readonly remove: (input: RemoveInput) => Effect.Effect<RemoveResult, FSUtil.Error>
 }
 
 export class Service extends Context.Service<Service, Interface>()("@opencode/FileMutation") {}
@@ -89,13 +58,6 @@ const layer = Layer.effect(
       existed,
     })
 
-    const removeResult = (target: Target, existed: boolean): RemoveResult => ({
-      operation: "remove",
-      target: target.canonical,
-      resource: target.resource,
-      existed,
-    })
-
     const write = Effect.fn("FileMutation.write")((input: WriteInput) =>
       withTargetLock(input.target)(
         Effect.gen(function* () {
@@ -122,62 +84,10 @@ const layer = Layer.effect(
       ),
     )
 
-    const create = Effect.fn("FileMutation.create")((input: WriteInput) =>
+    return Service.of({ write, writeTextPreservingBom })
-      withTargetLock(input.target)(
-        Effect.gen(function* () {
-          const write =
-            typeof input.content === "string"
-              ? fs.writeFileString(input.target.canonical, input.content, { flag: "wx" })
-              : fs.writeFile(input.target.canonical, input.content, { flag: "wx" })
-          yield* write.pipe(
-            Effect.catchReason("PlatformError", "NotFound", () =>
-              fs.ensureDir(dirname(input.target.canonical)).pipe(Effect.andThen(write)),
-            ),
-            Effect.catchReason("PlatformError", "AlreadyExists", () =>
-              Effect.fail(new TargetExistsError({ path: input.target.canonical })),
-            ),
-          )
-          return writeResult(input.target, false)
-        }),
-      ),
-    )
-
-    const writeIfUnchanged = Effect.fn("FileMutation.writeIfUnchanged")((input: ConditionalWriteInput) =>
-      withTargetLock(input.target)(
-        Effect.gen(function* () {
-          const current = yield* fs.readFile(input.target.canonical)
-          if (!sameBytes(current, input.expected)) {
-            return yield* new StaleContentError({ path: input.target.canonical })
-          }
-          yield* typeof input.content === "string"
-            ? fs.writeFileString(input.target.canonical, input.content)
-            : fs.writeFile(input.target.canonical, input.content)
-          return writeResult(input.target, true)
-        }),
-      ),
-    )
-
-    const remove = Effect.fn("FileMutation.remove")((input: RemoveInput) =>
-      withTargetLock(input.target)(
-        Effect.gen(function* () {
-          const existed = yield* fs.remove(input.target.canonical).pipe(
-            Effect.as(true),
-            Effect.catchReason("PlatformError", "NotFound", () => Effect.succeed(false)),
-          )
-          return removeResult(input.target, existed)
-        }),
-      ),
-    )
-
-    return Service.of({ create, write, writeTextPreservingBom, writeIfUnchanged, remove })
   }),
 )
 
-function sameBytes(left: Uint8Array, right: Uint8Array) {
-  if (left.length !== right.length) return false
-  return left.every((byte, index) => byte === right[index])
-}
-
 export const node = makeLocationNode({ service: Service, layer, deps: [FSUtil.node] })
 
 /**

packages/core/src/filesystem/search.ts

@@ -31,10 +31,7 @@ export const ripgrepLayer = Layer.effect(
     const location = yield* Location.Service
     const ripgrep = yield* Ripgrep.Service
     const scope = yield* Scope.Scope
-    const state = {
+    const files: string[] = []
-      files: [] as string[],
-      directories: [] as string[],
-    }
     const directories = new Set<string>()
     yield* ripgrep
       .find({
@@ -43,10 +40,9 @@ export const ripgrepLayer = Layer.effect(
         limit: location.vcs ? Number.MAX_SAFE_INTEGER : 100_000,
         onEntry: (entry) =>
           Effect.sync(() => {
-            state.files.push(entry.path)
+            files.push(entry.path)
             const parts = entry.path.split("/")
             parts.slice(0, -1).forEach((_, index) => directories.add(parts.slice(0, index + 1).join("/") + path.sep))
-            state.directories = Array.from(directories)
           }),
       })
       .pipe(Effect.orDie, Effect.asVoid, Effect.forkIn(scope))
@@ -106,10 +102,10 @@ export const ripgrepLayer = Layer.effect(
         Effect.gen(function* () {
           const items =
             input.type === "file"
-              ? state.files
+              ? files
               : input.type === "directory"
-                ? state.directories
+                ? Array.from(directories)
-                : [...state.files, ...state.directories]
+                : [...files, ...directories]
           return fuzzysort.go(input.query, items, { limit: input.limit ?? 50 }).map((item) => {
             const relative = item.target
             const type = relative.endsWith(path.sep) ? ("directory" as const) : ("file" as const)

packages/core/src/session.ts

@@ -410,7 +410,7 @@ const layer = Layer.effect(
       fork: Effect.fn("Session.fork")(function* (input) {
         const parent = yield* result.get(input.sessionID)
         const boundary = yield* db
-          .select({ id: SessionMessageTable.id, seq: SessionMessageTable.seq })
+          .select({ id: SessionMessageTable.id })
           .from(SessionMessageTable)
           .where(
             and(
@@ -429,13 +429,14 @@ const layer = Layer.effect(
           })
         if (!boundary) return yield* new ForkEmptyError({ sessionID: input.sessionID })
         const sessionID = SessionSchema.ID.create()
-        const instructionThrough =
+        // The fork adopts the parent's newest instruction values rather than the
-          input.boundary.type === "before" ? boundary.seq - 1 : yield* Bus.latestSequence(db, parent.id)
+        // values in effect at the boundary; copied history may contain frozen
+        // instruction-update text the initial baseline already reflects.
         yield* bus.publish(SessionEvent.Forked, {
           sessionID,
           parentID: parent.id,
           boundary: { ...input.boundary, messageID: boundary.id },
-          instructions: yield* InstructionState.valuesAt(db, parent.id, instructionThrough),
+          instructions: yield* InstructionState.current(db, parent.id),
         })
         return yield* result.get(sessionID).pipe(Effect.orDie)
       }),

packages/core/src/session/history.ts

@@ -80,10 +80,9 @@ export const entriesForRunner = Effect.fn("SessionHistory.entriesForRunner")(fun
     .transaction(() =>
       Effect.gen(function* () {
         const messages = yield* messageEntries(db, sessionID)
-        const assembled = yield* InstructionState.assemble(db, sessionID, instructions)
         return {
-          initial: assembled.initial,
+          initial: yield* InstructionState.initial(db, sessionID, instructions),
-          entries: [...messages, ...assembled.updates].toSorted((a, b) => a.seq - b.seq),
+          entries: messages,
         }
       }),
     )
@@ -106,10 +105,9 @@ export const preview = Effect.fn("SessionHistory.preview")(function* (
         )
         const settled = unsettled === -1 ? messages : messages.slice(0, unsettled)
         const assembled = yield* InstructionState.preview(db, sessionID, instructions, observed)
-        const entries = [...settled, ...assembled.updates].toSorted((a, b) => a.seq - b.seq)
         return {
           initial: assembled.initial,
-          messages: entries.map((entry) => entry.message),
+          messages: settled.map((entry) => entry.message),
           instructionUpdate: assembled.update,
         }
       }),

packages/core/src/session/instruction-state.ts

@@ -1,25 +1,20 @@
 export * as InstructionState from "./instruction-state"
 
-import { and, asc, desc, eq, gt, inArray, lte, sql } from "drizzle-orm"
+import { eq, inArray, sql } from "drizzle-orm"
-import { DateTime, Effect, Option, Schema } from "effect"
+import { Effect, Option, Schema } from "effect"
 import type { Database } from "../database/database"
-import { Bus } from "../bus"
+import type { Bus } from "../bus"
-import { EventTable } from "../event/sql"
 import { Instructions } from "../instructions/index"
 import { SessionEvent } from "./event"
-import { SessionMessage } from "./message"
-import { Event } from "@opencode-ai/schema/event"
 import { SessionSchema } from "./schema"
 import { InstructionBlobTable, InstructionStateTable } from "./sql"
 
 type DatabaseService = Database.Interface["db"]
 
-const decodeInstructionsUpdated = Schema.decodeUnknownSync(SessionEvent.InstructionsUpdated.data)
-const decodeForked = Schema.decodeUnknownSync(SessionEvent.Forked.data)
-
 export interface Observation extends Instructions.Admission {
   readonly sessionID: SessionSchema.ID
   readonly initial: boolean
+  readonly previous: Instructions.Values
   readonly current: Instructions.Values
 }
 
@@ -28,13 +23,14 @@ export const observe = Effect.fn("InstructionState.observe")(function* (
   instructions: Instructions.Instructions,
   sessionID: SessionSchema.ID,
 ): Effect.fn.Return<Observation, Instructions.InitializationBlocked> {
-  const [observed, stored] = yield* Effect.all([Instructions.read(instructions), ensure(db, sessionID)], {
+  const [observed, stored] = yield* Effect.all([Instructions.read(instructions), find(db, sessionID)], {
     concurrency: "unbounded",
   })
   const result = yield* observeAgainst(observed, stored?.current_values)
   return {
     sessionID,
     initial: !stored,
+    previous: stored?.current_values ?? {},
     ...result,
   }
 })
@@ -42,12 +38,20 @@ export const observe = Effect.fn("InstructionState.observe")(function* (
 export const commit = Effect.fn("InstructionState.commit")(function* (
   db: DatabaseService,
   bus: Bus.Interface,
+  instructions: Instructions.Instructions,
   observation: Observation,
 ) {
   if (!observation.initial && Object.keys(observation.delta).length === 0) return
+  // The rendered text is frozen into the durable event: replaying it later would
+  // require the Location-scoped registry that produced it.
+  const text = observation.initial ? "" : yield* renderUpdateText(db, instructions, observation)
   yield* bus.publish(
     SessionEvent.InstructionsUpdated,
-    { sessionID: observation.sessionID, delta: observation.delta },
+    {
+      sessionID: observation.sessionID,
+      delta: observation.delta,
+      ...(text.length > 0 ? { text } : {}),
+    },
     {
       // Initial sync establishes the baseline; unlike later deltas it is not chronological history.
       ...(observation.initial ? { metadata: { instructions: { initial: true } } } : {}),
@@ -56,13 +60,27 @@ export const commit = Effect.fn("InstructionState.commit")(function* (
   )
 })
 
+const renderUpdateText = Effect.fnUntraced(function* (
+  db: DatabaseService,
+  instructions: Instructions.Instructions,
+  observation: Observation,
+) {
+  const replaced = Object.entries(observation.previous).filter(([key]) => Object.hasOwn(observation.delta, key))
+  const blobs = yield* loadBlobs(db, replaced.map(([, hash]) => hash))
+  const previous = Object.fromEntries(replaced.map(([key, hash]) => [key, requireBlob(blobs, hash)]))
+  const admitted = new Map(
+    Object.entries(observation.blobs).map(([hash, value]) => [Instructions.Hash.make(hash), value]),
+  )
+  return Instructions.renderUpdate(instructions, previous, dereferenceDelta(observation.delta, admitted))
+})
+
 export const prepare = Effect.fn("InstructionState.prepare")(function* (
   db: DatabaseService,
   bus: Bus.Interface,
   instructions: Instructions.Instructions,
   sessionID: SessionSchema.ID,
 ) {
-  yield* commit(db, bus, yield* observe(db, instructions, sessionID))
+  yield* commit(db, bus, instructions, yield* observe(db, instructions, sessionID))
 })
 
 export const apply = Effect.fn("InstructionState.apply")(function* (
@@ -140,79 +158,24 @@ export const reset = Effect.fn("InstructionState.reset")(function* (db: Database
     .pipe(Effect.orDie)
 })
 
-export const rebuild = Effect.fn("InstructionState.rebuild")(function* (
+/** Renders the epoch baseline shown at the start of every model request. */
-  db: DatabaseService,
+export const initial = Effect.fn("InstructionState.initial")(function* (
-  sessionID: SessionSchema.ID,
-) {
-  const state = yield* stateFromEvents(db, sessionID)
-  if (!state) {
-    yield* reset(db, sessionID)
-    return undefined
-  }
-  yield* db
-    .insert(InstructionStateTable)
-    .values(state)
-    .onConflictDoUpdate({
-      target: InstructionStateTable.session_id,
-      set: {
-        epoch_start: state.epoch_start,
-        through_seq: state.through_seq,
-        initial_values: state.initial_values,
-        current_values: state.current_values,
-      },
-    })
-    .run()
-    .pipe(Effect.orDie)
-  return state
-})
-
-const assembleState = Effect.fnUntraced(function* (
-  db: DatabaseService,
-  sessionID: SessionSchema.ID,
-  instructions: Instructions.Instructions,
-  state: typeof InstructionStateTable.$inferSelect,
-) {
-  const rows = yield* instructionUpdatesAfter(db, sessionID, state.epoch_start)
-  const updates = rows.map((row) => ({
-    row,
-    delta: decodeInstructionsUpdated(row.data).delta,
-  }))
-  const blobs = yield* loadBlobs(db, [
-    ...Object.values(state.initial_values),
-    ...updates.flatMap((update) =>
-      Object.values(update.delta).filter((hash): hash is Instructions.Hash => hash !== "removed"),
-    ),
-  ])
-  const valuesAtStart = dereference(state.initial_values, blobs)
-  let values = valuesAtStart
-  const result: Array<{ readonly seq: number; readonly message: SessionMessage.System }> = []
-  for (const update of updates) {
-    const delta = dereferenceDelta(update.delta, blobs)
-    const text = Instructions.renderUpdate(instructions, values, delta)
-    if (text.length > 0)
-      result.push({
-        seq: update.row.seq,
-        message: SessionMessage.System.make({
-          id: SessionMessage.ID.fromEvent(Event.ID.make(update.row.id)),
-          type: "system",
-          text,
-          time: { created: DateTime.makeUnsafe(update.row.created) },
-        }),
-      })
-    values = Instructions.applyDelta(values, delta)
-  }
-  return { initial: Instructions.renderInitial(instructions, valuesAtStart), updates: result, current: values }
-})
-
-export const assemble = Effect.fn("InstructionState.assemble")(function* (
   db: DatabaseService,
   sessionID: SessionSchema.ID,
   instructions: Instructions.Instructions,
 ) {
   const state = yield* find(db, sessionID)
   if (!state) return yield* Effect.die(new Error(`Instruction state not found during assembly: ${sessionID}`))
-  const assembled = yield* assembleState(db, sessionID, instructions, state)
+  const blobs = yield* loadBlobs(db, Object.values(state.initial_values))
-  return { initial: assembled.initial, updates: assembled.updates }
+  return Instructions.renderInitial(instructions, dereference(state.initial_values, blobs))
+})
+
+/** The current instruction values, used to seed a fork's baseline. */
+export const current = Effect.fn("InstructionState.current")(function* (
+  db: DatabaseService,
+  sessionID: SessionSchema.ID,
+) {
+  return (yield* find(db, sessionID))?.current_values
 })
 
 export const preview = Effect.fn("InstructionState.preview")(function* (
@@ -221,20 +184,26 @@ export const preview = Effect.fn("InstructionState.preview")(function* (
   instructions: Instructions.Instructions,
   observed: Instructions.ReadResult,
 ) {
-  const state = yield* readState(db, sessionID)
+  const state = yield* find(db, sessionID)
   const result = yield* observeAgainst(observed, state?.current_values)
-  const blobs = new Map<Instructions.Hash, Schema.Json>(
+  const observedBlobs = new Map<Instructions.Hash, Schema.Json>(
     Object.entries(result.blobs).map(([hash, value]) => [Instructions.Hash.make(hash), value]),
   )
   if (!state) {
-    const values = dereference(result.current, blobs)
+    const values = dereference(result.current, observedBlobs)
-    return { initial: Instructions.renderInitial(instructions, values), updates: [], update: "" }
+    return { initial: Instructions.renderInitial(instructions, values), update: "" }
   }
-  const assembled = yield* assembleState(db, sessionID, instructions, state)
+  const stored = yield* loadBlobs(db, [
+    ...Object.values(state.initial_values),
+    ...Object.values(state.current_values),
+  ])
   return {
-    initial: assembled.initial,
+    initial: Instructions.renderInitial(instructions, dereference(state.initial_values, stored)),
-    updates: assembled.updates,
+    update: Instructions.renderUpdate(
-    update: Instructions.renderUpdate(instructions, assembled.current, dereferenceDelta(result.delta, blobs)),
+      instructions,
+      dereference(state.current_values, stored),
+      dereferenceDelta(result.delta, new Map([...stored, ...observedBlobs])),
+    ),
   }
 })
 
@@ -255,46 +224,6 @@ const find = Effect.fnUntraced(function* (db: DatabaseService, sessionID: Sessio
     .pipe(Effect.orDie)
 })
 
-const ensure = Effect.fnUntraced(function* (db: DatabaseService, sessionID: SessionSchema.ID) {
-  const stored = yield* find(db, sessionID)
-  if (!stored) return yield* rebuild(db, sessionID)
-  const latest = yield* latestRelevantSequence(db, sessionID)
-  if (!latest || latest.seq <= stored.through_seq) return stored
-  return yield* rebuild(db, sessionID)
-})
-
-const readState = Effect.fnUntraced(function* (db: DatabaseService, sessionID: SessionSchema.ID) {
-  const stored = yield* find(db, sessionID)
-  if (!stored) return yield* stateFromEvents(db, sessionID)
-  const latest = yield* latestRelevantSequence(db, sessionID)
-  if (!latest || latest.seq <= stored.through_seq) return stored
-  return yield* stateFromEvents(db, sessionID)
-})
-
-const stateFromEvents = Effect.fnUntraced(function* (db: DatabaseService, sessionID: SessionSchema.ID) {
-  const folded = fold(yield* instructionEvents(db, sessionID))
-  return folded ? foldedState(sessionID, folded) : undefined
-})
-
-export const valuesAt = Effect.fn("InstructionState.valuesAt")(function* (
-  db: DatabaseService,
-  sessionID: SessionSchema.ID,
-  through: number,
-) {
-  return fold(yield* instructionEvents(db, sessionID, through))?.current
-})
-
-const latestRelevantSequence = Effect.fnUntraced(function* (db: DatabaseService, sessionID: SessionSchema.ID) {
-  return yield* db
-    .select({ seq: EventTable.seq })
-    .from(EventTable)
-    .where(and(eq(EventTable.aggregate_id, sessionID), inArray(EventTable.type, relevantEventTypes)))
-    .orderBy(desc(EventTable.seq))
-    .limit(1)
-    .get()
-    .pipe(Effect.orDie)
-})
-
 const insertBlobs = Effect.fnUntraced(function* (db: DatabaseService, blobs: Readonly<Record<string, Schema.Json>>) {
   const rows = Object.entries(blobs).map(([hash, value]) => ({ hash: Instructions.Hash.make(hash), value }))
   if (rows.length === 0) return
@@ -339,106 +268,3 @@ function requireBlob(blobs: ReadonlyMap<Instructions.Hash, Schema.Json>, hash: I
   if (value === undefined) throw new Error(`Instruction blob not found: ${hash}`)
   return value
 }
-
-const instructionEventType = Bus.versionedType(
-  SessionEvent.InstructionsUpdated.type,
-  SessionEvent.InstructionsUpdated.durable.version,
-)
-const compactionEventType = Bus.versionedType(
-  SessionEvent.Compaction.Ended.type,
-  SessionEvent.Compaction.Ended.durable.version,
-)
-const movedEventType = Bus.versionedType(SessionEvent.Moved.type, SessionEvent.Moved.durable.version)
-const revertedEventType = Bus.versionedType(
-  SessionEvent.RevertEvent.Committed.type,
-  SessionEvent.RevertEvent.Committed.durable.version,
-)
-const forkedEventType = Bus.versionedType(SessionEvent.Forked.type, SessionEvent.Forked.durable.version)
-const relevantEventTypes = [
-  forkedEventType,
-  instructionEventType,
-  compactionEventType,
-  movedEventType,
-  revertedEventType,
-]
-
-type InstructionEventRow = typeof EventTable.$inferSelect
-
-const instructionEvents = Effect.fnUntraced(function* (
-  db: DatabaseService,
-  sessionID: SessionSchema.ID,
-  through?: number,
-): Effect.fn.Return<ReadonlyArray<InstructionEventRow>> {
-  return yield* eventRows(db, sessionID, relevantEventTypes, undefined, through)
-})
-
-const instructionUpdatesAfter = Effect.fnUntraced(function* (
-  db: DatabaseService,
-  sessionID: SessionSchema.ID,
-  after: number,
-) {
-  return yield* eventRows(db, sessionID, [instructionEventType], after)
-})
-
-const eventRows = Effect.fnUntraced(function* (
-  db: DatabaseService,
-  sessionID: SessionSchema.ID,
-  types: ReadonlyArray<string>,
-  after?: number,
-  through?: number,
-): Effect.fn.Return<ReadonlyArray<InstructionEventRow>> {
-  return yield* db
-    .select()
-    .from(EventTable)
-    .where(
-      and(
-        eq(EventTable.aggregate_id, sessionID),
-        inArray(EventTable.type, types),
-        after === undefined ? undefined : gt(EventTable.seq, after),
-        through === undefined ? undefined : lte(EventTable.seq, through),
-      ),
-    )
-    .orderBy(asc(EventTable.seq))
-    .all()
-    .pipe(Effect.orDie)
-})
-
-function fold(rows: ReadonlyArray<InstructionEventRow>) {
-  return rows.reduce<
-    | {
-        readonly epochStart: number
-        readonly throughSeq: number
-        readonly initial: Instructions.Values
-        readonly current: Instructions.Values
-      }
-    | undefined
-  >((state, row) => {
-    if (row.type === forkedEventType) {
-      const instructions = decodeForked(row.data).instructions
-      return instructions
-        ? { epochStart: row.seq, throughSeq: row.seq, initial: instructions, current: instructions }
-        : undefined
-    }
-    if (row.type === movedEventType || row.type === revertedEventType) return undefined
-    if (row.type === compactionEventType)
-      return state
-        ? { epochStart: row.seq, throughSeq: row.seq, initial: state.current, current: state.current }
-        : undefined
-    if (row.type !== instructionEventType) return state
-    const delta = decodeInstructionsUpdated(row.data).delta
-    const current = Instructions.applyHashDelta(state?.current ?? {}, delta)
-    return state
-      ? { ...state, throughSeq: row.seq, current }
-      : { epochStart: row.seq, throughSeq: row.seq, initial: current, current }
-  }, undefined)
-}
-
-function foldedState(sessionID: SessionSchema.ID, folded: NonNullable<ReturnType<typeof fold>>) {
-  return {
-    session_id: sessionID,
-    epoch_start: folded.epochStart,
-    through_seq: folded.throughSeq,
-    initial_values: folded.initial,
-    current_values: folded.current,
-  }
-}

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

@@ -179,7 +179,18 @@ export function update(adapter: Adapter, event: SessionEvent.Event) {
       "session.execution.succeeded": () => clearCurrentRetry,
       "session.execution.failed": () => clearCurrentRetry,
       "session.execution.interrupted": () => clearCurrentRetry,
-      "session.instructions.updated": () => Effect.void,
+      "session.instructions.updated": (event) => {
+        if (event.data.text === undefined) return Effect.void
+        return adapter.appendMessage(
+          SessionMessage.System.make({
+            id: SessionMessage.ID.fromEvent(event.id),
+            type: "system",
+            text: event.data.text,
+            metadata: event.metadata,
+            time: { created: event.created },
+          }),
+        )
+      },
       "session.synthetic": (event) => {
         return adapter.appendMessage(
           SessionMessage.Synthetic.make({

packages/core/src/session/pending.ts

@@ -12,10 +12,8 @@ import {
   User,
   UserData,
 } from "@opencode-ai/schema/session-pending"
-import { Event } from "@opencode-ai/schema/event"
 import type { Database } from "../database/database"
 import { Bus } from "../bus"
-import { EventTable } from "../event/sql"
 import { KeyedMutex } from "../effect/keyed-mutex"
 import { SessionEvent } from "./event"
 import { SessionMessage } from "./message"
@@ -37,11 +35,7 @@ const decodeUser = Schema.decodeUnknownSync(UserData)
 const encodeUser = Schema.encodeSync(UserData)
 const decodeSynthetic = Schema.decodeUnknownSync(SyntheticData)
 const encodeSynthetic = Schema.encodeSync(SyntheticData)
-const decodeAdmittedEvent = Schema.decodeUnknownOption(SessionEvent.InputAdmitted.data)
+const decodeMessage = Schema.decodeUnknownSync(SessionMessage.Info)
-const admittedEventType = Bus.versionedType(
-  SessionEvent.InputAdmitted.type,
-  SessionEvent.InputAdmitted.durable.version,
-)
 const inboxLocks = KeyedMutex.makeUnsafe<SessionSchema.ID>()
 
 export class LifecycleConflict extends Schema.TaggedErrorClass<LifecycleConflict>()(
@@ -103,46 +97,35 @@ export const compaction = Effect.fn("SessionPending.compaction")(function* (
   return entry.type === "compaction" ? entry : undefined
 })
 
-/**
+const promotedFromMessage = Effect.fn("SessionPending.promotedFromMessage")(function* (
- * Reconstruct the admitted record for a pending row that was already consumed
- * by promotion. The projected `session_message` row proves promotion happened;
- * the durable `session.input.admitted` event retains the exact admitted
- * message, including delivery.
- */
-const promotedFromHistory = Effect.fn("SessionPending.promotedFromHistory")(function* (
   db: DatabaseService,
   sessionID: SessionSchema.ID,
   id: SessionMessage.ID,
+  delivery: Delivery,
 ) {
-  const message = yield* db
+  const row = yield* db
     .select()
     .from(SessionMessageTable)
     .where(eq(SessionMessageTable.id, id))
     .get()
     .pipe(Effect.orDie)
-  if (message === undefined) return undefined
+  if (row === undefined) return undefined
-  if (message.session_id !== sessionID || (message.type !== "user" && message.type !== "synthetic"))
+  if (row.session_id !== sessionID || (row.type !== "user" && row.type !== "synthetic"))
     return yield* Effect.die(new LifecycleConflict({ id }))
-  const rows = yield* db
+  const message = decodeMessage({ ...row.data, id: row.id, type: row.type })
-    .select()
+  const base = { id, sessionID, timeCreated: message.time.created, delivery }
-    .from(EventTable)
+  if (message.type === "user")
-    .where(and(eq(EventTable.aggregate_id, sessionID), eq(EventTable.type, admittedEventType)))
+    return User.make({
-    .all()
+      ...base,
-    .pipe(Effect.orDie)
+      type: "user",
-  for (const row of rows) {
+      data: decodeUser(message),
-    const decoded = decodeAdmittedEvent(row.data)
+    })
-    if (decoded._tag !== "Some" || decoded.value.inputID !== id) continue
+  if (message.type === "synthetic")
-    const base = {
+    return Synthetic.make({
-      id,
+      ...base,
-      sessionID,
+      type: "synthetic",
-      timeCreated: DateTime.makeUnsafe(row.created),
+      data: decodeSynthetic(message),
-    }
+    })
-    return decoded.value.input.type === "user"
-      ? User.make({ ...base, ...decoded.value.input })
-      : Synthetic.make({ ...base, ...decoded.value.input })
-  }
-  // A projected message without an admitted event in this aggregate (for
-  // example fork-copied history) is not a retryable admission.
   return yield* Effect.die(new LifecycleConflict({ id }))
 })
 
@@ -160,7 +143,7 @@ export const admit = Effect.fn("SessionPending.admit")(function* (
     if (existing.type === "compaction") return yield* Effect.die(new LifecycleConflict({ id: request.id }))
     return existing
   }
-  const promoted = yield* promotedFromHistory(db, request.sessionID, request.id)
+  const promoted = yield* promotedFromMessage(db, request.sessionID, request.id, request.input.delivery)
   if (promoted !== undefined) return promoted
   return yield* bus
     .publish(SessionEvent.InputAdmitted, {
@@ -426,7 +409,7 @@ const publish = Effect.fn("SessionPending.publish")(function* (
         .pipe(
           Effect.catchDefect((defect) =>
             defect instanceof LifecycleConflict
-              ? promotedFromHistory(db, sessionID, entry.id).pipe(
+              ? promotedFromMessage(db, sessionID, entry.id, entry.delivery).pipe(
                   Effect.flatMap((stored) => (stored !== undefined ? Effect.void : Effect.die(defect))),
                 )
               : Effect.die(defect),

packages/core/src/session/projector.ts

@@ -1,6 +1,6 @@
 export * as SessionProjector from "./projector"
 
-import { and, asc, desc, eq, gt, gte, inArray, lt, lte, sql } from "drizzle-orm"
+import { and, asc, desc, eq, gt, gte, lt, lte, sql } from "drizzle-orm"
 import { DateTime, Effect, Layer, Schema, Stream } from "effect"
 import { Database } from "../database/database"
 import { Bus } from "../bus"
@@ -21,10 +21,7 @@ import { Money } from "@opencode-ai/schema/money"
 
 type DatabaseService = Database.Interface["db"]
 type CurrentDurableEvent = Extract<SessionEvent.Event, { readonly durable: object }>
-type MessageEvent = Exclude<
+type MessageEvent = Exclude<CurrentDurableEvent, typeof SessionEvent.Forked.Type | typeof SessionEvent.Deleted.Type>
-  CurrentDurableEvent,
-  typeof SessionEvent.Forked.Type | typeof SessionEvent.Deleted.Type | typeof SessionEvent.InstructionsUpdated.Type
->
 
 const decodeMessage = Schema.decodeUnknownSync(SessionMessage.Info)
 const encodeMessage = Schema.encodeSync(SessionMessage.Info)
@@ -255,66 +252,22 @@ const projectFork = Effect.fn("SessionProjector.projectFork")(function* (
       .pipe(Effect.orDie)
     if (rows.length === 0) break
 
-    const idMap = new Map(rows.map((row) => [row.id, SessionMessage.ID.create()]))
     yield* db
       .insert(SessionMessageTable)
       .values(
-        rows.map((row) => {
+        rows.map((row) => ({
-          const id = idMap.get(row.id)
+          id: SessionMessage.ID.create(),
-          if (!id) throw new Error(`Fork message ID mapping missing: ${row.id}`)
+          session_id: event.data.sessionID,
-          return {
+          type: row.type,
-            id,
+          seq: row.seq,
-            session_id: event.data.sessionID,
+          time_created: row.time_created,
-            type: row.type,
+          time_updated: row.time_updated,
-            seq: row.seq,
+          data: row.data,
-            time_created: row.time_created,
+        })),
-            time_updated: row.time_updated,
-            data: row.data,
-          }
-        }),
       )
       .run()
       .pipe(Effect.orDie)
 
-    const pendingRows = yield* db
-      .select()
-      .from(SessionPendingTable)
-      .where(
-        and(
-          eq(SessionPendingTable.session_id, event.data.parentID),
-          inArray(
-            SessionPendingTable.id,
-            rows.map((row) => row.id),
-          ),
-        ),
-      )
-      .all()
-      .pipe(Effect.orDie)
-    if (pendingRows.length > 0) {
-      yield* db
-        .insert(SessionPendingTable)
-        .values(
-          pendingRows.flatMap((row) => {
-            const id = idMap.get(row.id)
-            return id && row.type !== "compaction"
-              ? [
-                  {
-                    id,
-                    session_id: event.data.sessionID,
-                    type: row.type,
-                    data: row.data,
-                    delivery: row.delivery,
-                    admitted_seq: row.admitted_seq,
-                    time_created: row.time_created,
-                  },
-                ]
-              : []
-          }),
-        )
-        .run()
-        .pipe(Effect.orDie)
-    }
-
     cursor = rows.at(-1)!.seq
   }
   if (copiedSeq !== undefined) yield* Bus.reserveSequence(db, event.data.sessionID, copiedSeq)
@@ -682,7 +635,10 @@ const layer = Layer.effectDiscard(
     yield* bus.project(SessionEvent.Execution.Failed, (event) => run(db, event))
     yield* bus.project(SessionEvent.Execution.Interrupted, (event) => run(db, event))
     yield* bus.project(SessionEvent.InstructionsUpdated, (event) =>
-      InstructionState.apply(db, event.data.sessionID, event.durable.seq, event.data.delta),
+      Effect.gen(function* () {
+        yield* run(db, event)
+        yield* InstructionState.apply(db, event.data.sessionID, event.durable.seq, event.data.delta)
+      }),
     )
     yield* bus.project(SessionEvent.Synthetic, (event) => run(db, event))
     yield* bus.project(SessionEvent.Skill.Activated, (event) => run(db, event))

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

@@ -18,8 +18,9 @@ export function isRetryable(error: AIError) {
   switch (error.reason._tag) {
     case "RateLimit":
     case "ProviderInternal":
-    case "Transport":
       return true
+    case "Transport":
+      return error.reason.delivery === undefined || error.reason.delivery === "not-sent"
     case "InvalidProviderOutput":
       return error.reason.classification === "incomplete-stream"
     case "Authentication":

packages/core/test/file-mutation.test.ts

@@ -89,68 +89,6 @@ describe("FileMutation", () => {
     ),
   )
 
-  it.live("rejects create when a prospective target appears after resolution", () =>
-    withTmp((directory) =>
-      Effect.gen(function* () {
-        const targetPath = path.join(directory, "appeared.txt")
-        const target = yield* (yield* LocationMutation.Service).resolve({ path: "appeared.txt" })
-        yield* Effect.promise(() => fs.writeFile(targetPath, "winner"))
-
-        expect(
-          yield* (yield* FileMutation.Service).create({ target, content: "replacement" }).pipe(Effect.flip),
-        ).toMatchObject({
-          _tag: "FileMutation.TargetExistsError",
-        })
-        expect(yield* Effect.promise(() => fs.readFile(targetPath, "utf8"))).toBe("winner")
-      }).pipe(provide(directory)),
-    ),
-  )
-
-  it.live("creates when an existing target disappears after resolution", () =>
-    withTmp((directory) =>
-      Effect.gen(function* () {
-        const targetPath = path.join(directory, "removed.txt")
-        yield* Effect.promise(() => fs.writeFile(targetPath, "before"))
-        const target = yield* (yield* LocationMutation.Service).resolve({ path: "removed.txt" })
-        yield* Effect.promise(() => fs.rm(targetPath))
-
-        expect(yield* (yield* FileMutation.Service).create({ target, content: "after" })).toEqual({
-          operation: "write",
-          target: target.canonical,
-          resource: "removed.txt",
-          existed: false,
-        })
-        expect(yield* Effect.promise(() => fs.readFile(targetPath, "utf8"))).toBe("after")
-      }).pipe(provide(directory)),
-    ),
-  )
-
-  it.live("removes an existing internal file", () =>
-    withTmp((directory) =>
-      Effect.gen(function* () {
-        const targetPath = path.join(directory, "remove.txt")
-        yield* Effect.promise(() => fs.writeFile(targetPath, "remove"))
-        const target = yield* (yield* LocationMutation.Service).resolve({ path: "remove.txt" })
-        const result = yield* (yield* FileMutation.Service).remove({ target })
-
-        expect(result).toEqual({
-          operation: "remove",
-          target: target.canonical,
-          resource: "remove.txt",
-          existed: true,
-        })
-        expect(
-          yield* Effect.promise(() =>
-            fs.stat(targetPath).then(
-              () => true,
-              () => false,
-            ),
-          ),
-        ).toBe(false)
-      }).pipe(provide(directory)),
-    ),
-  )
-
   it.live("writes an explicitly resolved external target", () =>
     withTmp((directory) =>
       withTmp((outside) =>
@@ -171,49 +109,6 @@ describe("FileMutation", () => {
     ),
   )
 
-  it.live("removes an explicitly resolved external target", () =>
-    withTmp((directory) =>
-      withTmp((outside) =>
-        Effect.gen(function* () {
-          const targetPath = path.join(outside, "external.txt")
-          yield* Effect.promise(() => fs.writeFile(targetPath, "external"))
-          const target = yield* (yield* LocationMutation.Service).resolve({ path: targetPath })
-          const result = yield* (yield* FileMutation.Service).remove({ target })
-
-          expect(result).toEqual({
-            operation: "remove",
-            target: target.canonical,
-            resource: target.resource,
-            existed: true,
-          })
-          expect(
-            yield* Effect.promise(() =>
-              fs.stat(targetPath).then(
-                () => true,
-                () => false,
-              ),
-            ),
-          ).toBe(false)
-        }).pipe(provide(directory)),
-      ),
-    ),
-  )
-
-  it.live("reports a missing target as not removed without checking existence first", () =>
-    withTmp((directory) =>
-      Effect.gen(function* () {
-        const target = yield* (yield* LocationMutation.Service).resolve({ path: "missing.txt" })
-
-        expect(yield* (yield* FileMutation.Service).remove({ target })).toEqual({
-          operation: "remove",
-          target: target.canonical,
-          resource: "missing.txt",
-          existed: false,
-        })
-      }).pipe(provide(directory)),
-    ),
-  )
-
   it.live("serializes concurrent writes to the same canonical target", () =>
     withTmp((directory) =>
       Effect.gen(function* () {
@@ -257,63 +152,6 @@ describe("FileMutation", () => {
     ),
   )
 
-  it.live("allows only one concurrent conditional write based on the same bytes", () =>
-    withTmp((directory) =>
-      Effect.gen(function* () {
-        const targetPath = path.join(directory, "shared.txt")
-        yield* Effect.promise(() => fs.writeFile(targetPath, "initial"))
-        const firstStarted = yield* Deferred.make<void>()
-        const releaseFirst = yield* Deferred.make<void>()
-        let writes = 0
-        const filesystem = instrumentWrites((write) =>
-          Effect.gen(function* () {
-            writes++
-            if (writes === 1) {
-              yield* Deferred.succeed(firstStarted, undefined)
-              yield* Deferred.await(releaseFirst)
-            }
-            yield* write
-          }),
-        )
-
-        yield* Effect.gen(function* () {
-          const mutation = yield* LocationMutation.Service
-          const files = yield* FileMutation.Service
-          const target = yield* mutation.resolve({ path: "shared.txt" })
-          const expected = new TextEncoder().encode("initial")
-          const first = yield* files.writeIfUnchanged({ target, expected, content: "first" }).pipe(Effect.forkChild)
-          yield* Deferred.await(firstStarted)
-          const second = yield* files
-            .writeIfUnchanged({ target, expected, content: "second" })
-            .pipe(Effect.flip, Effect.forkChild)
-
-          yield* Deferred.succeed(releaseFirst, undefined)
-          yield* Fiber.join(first)
-          expect(yield* Fiber.join(second)).toMatchObject({ _tag: "FileMutation.StaleContentError" })
-          expect(yield* Effect.promise(() => fs.readFile(targetPath, "utf8"))).toBe("first")
-          expect(writes).toBe(1)
-        }).pipe(provide(directory, filesystem))
-      }),
-    ),
-  )
-
-  it.live("rejects a conditional write when target content is already stale", () =>
-    withTmp((directory) =>
-      Effect.gen(function* () {
-        const targetPath = path.join(directory, "stale.txt")
-        yield* Effect.promise(() => fs.writeFile(targetPath, "current"))
-        const target = yield* (yield* LocationMutation.Service).resolve({ path: "stale.txt" })
-
-        expect(
-          yield* (yield* FileMutation.Service)
-            .writeIfUnchanged({ target, expected: new TextEncoder().encode("older"), content: "replacement" })
-            .pipe(Effect.flip),
-        ).toMatchObject({ _tag: "FileMutation.StaleContentError", path: target.canonical })
-        expect(yield* Effect.promise(() => fs.readFile(targetPath, "utf8"))).toBe("current")
-      }).pipe(provide(directory)),
-    ),
-  )
-
   it.live("allows distinct canonical targets to proceed independently", () =>
     withTmp((directory) =>
       Effect.gen(function* () {

packages/core/test/instruction-state.test.ts

@@ -14,7 +14,7 @@ import { AbsolutePath } from "@opencode-ai/core/schema"
 import { InstructionState } from "@opencode-ai/core/session/instruction-state"
 import { SessionProjector } from "@opencode-ai/core/session/projector"
 import { SessionSchema } from "@opencode-ai/core/session/schema"
-import { InstructionBlobTable, InstructionStateTable, SessionTable } from "@opencode-ai/core/session/sql"
+import { InstructionBlobTable, InstructionStateTable, SessionMessageTable, SessionTable } from "@opencode-ai/core/session/sql"
 import { testEffect } from "./lib/effect"
 
 const it = testEffect(AppNodeBuilder.build(LayerNode.group([Database.node, Bus.node, SessionProjector.node])))
@@ -105,6 +105,7 @@ describe("InstructionState", () => {
       expect(observation).toEqual({
         sessionID,
         initial: true,
+        previous: {},
         current: {
           "test/first": Instructions.hash("first"),
           "test/second": Instructions.hash("second"),
@@ -156,7 +157,7 @@ describe("InstructionState", () => {
 
       const initial = yield* InstructionState.observe(db, instructions, sessionID)
       expect(reads).toBe(2)
-      yield* InstructionState.commit(db, events, initial)
+      yield* InstructionState.commit(db, events, instructions, initial)
       expect(reads).toBe(2)
 
       current = "changed"
@@ -166,6 +167,10 @@ describe("InstructionState", () => {
       expect(changed).toMatchObject({
         sessionID,
         initial: false,
+        previous: {
+          "test/current": Instructions.hash("initial"),
+          "test/retired": Instructions.hash("retired"),
+        },
         current: { "test/current": Instructions.hash("changed") },
         delta: {
           "test/current": Instructions.hash("changed"),
@@ -173,7 +178,7 @@ describe("InstructionState", () => {
         },
         blobs: { [Instructions.hash("changed")]: "changed" },
       })
-      yield* InstructionState.commit(db, events, changed)
+      yield* InstructionState.commit(db, events, instructions, changed)
       expect(reads).toBe(4)
       yield* unsubscribe
 
@@ -190,6 +195,11 @@ describe("InstructionState", () => {
           "test/retired": "removed",
         },
       ])
+      // The chronological update text is frozen into the event; the baseline has none.
+      expect((yield* instructionEvents(db, sessionID)).map((event) => event.data.text)).toEqual([
+        undefined,
+        "changed\n\nRemoved retired",
+      ])
       expect(yield* db.select().from(InstructionStateTable).get().pipe(Effect.orDie)).toMatchObject({
         initial_values: {
           "test/current": Instructions.hash("initial"),
@@ -222,18 +232,19 @@ describe("InstructionState", () => {
       expect(observation).toEqual({
         sessionID,
         initial: false,
+        previous: { "test/context": Instructions.hash("unchanged") },
         current: { "test/context": Instructions.hash("unchanged") },
         delta: {},
         blobs: {},
       })
-      yield* InstructionState.commit(db, events, observation)
+      yield* InstructionState.commit(db, events, instructions, observation)
 
       expect(yield* instructionEvents(db, sessionID)).toEqual(beforeEvents)
       expect(yield* db.select().from(InstructionBlobTable).all().pipe(Effect.orDie)).toEqual(beforeBlobs)
     }),
   )
 
-  it.effect("assembles a fresh private update without repairing a missing cache", () =>
+  it.effect("treats a missing state row as a fresh baseline without repairing it", () =>
     Effect.gen(function* () {
       const sessionID = SessionSchema.ID.make("ses_instruction_generate")
       const { db, events } = yield* setup(sessionID)
@@ -254,7 +265,7 @@ describe("InstructionState", () => {
 
       const assembled = yield* preview(db, sessionID, instructions)
 
-      expect(assembled).toEqual({ initial: "Initial context", updates: [], update: "Changed context" })
+      expect(assembled).toEqual({ initial: "Changed context", update: "" })
       expect(yield* instructionEvents(db, sessionID)).toEqual(beforeEvents)
       expect(yield* db.select().from(InstructionBlobTable).all().pipe(Effect.orDie)).toEqual(beforeBlobs)
       expect(
@@ -268,7 +279,7 @@ describe("InstructionState", () => {
     }),
   )
 
-  it.effect("reads through a stale cache without repairing it", () =>
+  it.effect("trusts the projected state without consulting durable events", () =>
     Effect.gen(function* () {
       const sessionID = SessionSchema.ID.make("ses_instruction_generate_stale")
       const { db, events } = yield* setup(sessionID)
@@ -280,6 +291,7 @@ describe("InstructionState", () => {
       yield* InstructionState.prepare(db, events, instructions, sessionID)
       value = "Committed update"
       yield* InstructionState.prepare(db, events, instructions, sessionID)
+      // Tamper with the projected state; the authoritative row wins over event history.
       yield* db
         .update(InstructionStateTable)
         .set({ through_seq: 0, current_values: { "test/context": Instructions.hash("Initial context") } })
@@ -294,7 +306,6 @@ describe("InstructionState", () => {
       const assembled = yield* preview(db, sessionID, instructions)
 
       expect(assembled.initial).toBe("Initial context")
-      expect(assembled.updates.map((entry) => entry.message.text)).toEqual(["Committed update"])
       expect(assembled.update).toBe("Private update")
       expect(yield* instructionEvents(db, sessionID)).toEqual(beforeEvents)
       expect(yield* db.select().from(InstructionBlobTable).all().pipe(Effect.orDie)).toEqual(beforeBlobs)
@@ -302,6 +313,41 @@ describe("InstructionState", () => {
     }),
   )
 
+  it.effect("persists chronological updates as system messages", () =>
+    Effect.gen(function* () {
+      const sessionID = SessionSchema.ID.make("ses_instruction_messages")
+      const { db, events } = yield* setup(sessionID)
+      let value = "Initial context"
+      const instructions = source(
+        "test/context",
+        Effect.sync(() => value),
+      )
+      const messages = () =>
+        db
+          .select()
+          .from(SessionMessageTable)
+          .where(and(eq(SessionMessageTable.session_id, sessionID), eq(SessionMessageTable.type, "system")))
+          .orderBy(asc(SessionMessageTable.seq))
+          .all()
+          .pipe(Effect.orDie)
+
+      // The initial baseline is not chronological history and produces no message.
+      yield* InstructionState.prepare(db, events, instructions, sessionID)
+      expect(yield* messages()).toEqual([])
+
+      value = "Changed context"
+      yield* InstructionState.prepare(db, events, instructions, sessionID)
+      const rows = yield* messages()
+      expect(rows).toHaveLength(1)
+      expect(rows[0]?.data).toMatchObject({ text: "Changed context" })
+      expect(rows.map((row) => row.seq)).toEqual([(yield* instructionEvents(db, sessionID)).at(-1)!.seq])
+
+      // A no-op observation adds nothing.
+      yield* InstructionState.prepare(db, events, instructions, sessionID)
+      expect(yield* messages()).toHaveLength(1)
+    }),
+  )
+
   it.effect("assembles initial instructions without persisting a baseline", () =>
     Effect.gen(function* () {
       const sessionID = SessionSchema.ID.make("ses_instruction_generate_initial")
@@ -310,7 +356,6 @@ describe("InstructionState", () => {
 
       expect(yield* preview(db, sessionID, instructions)).toEqual({
         initial: "Initial context",
-        updates: [],
         update: "",
       })
       expect(yield* instructionEvents(db, sessionID)).toEqual([])
@@ -336,7 +381,6 @@ describe("InstructionState", () => {
 
       expect(yield* preview(db, sessionID, instructions)).toEqual({
         initial: "Committed context",
-        updates: [],
         update: "",
       })
       expect(yield* instructionEvents(db, sessionID)).toEqual(beforeEvents)
@@ -388,7 +432,7 @@ describe("InstructionState", () => {
       for (const next of ["initial", "changed", "changed", Instructions.removed] as const) {
         value = next
         yield* InstructionState.observe(db, observedInstructions, observedSessionID).pipe(
-          Effect.flatMap((observation) => InstructionState.commit(db, events, observation)),
+          Effect.flatMap((observation) => InstructionState.commit(db, events, observedInstructions, observation)),
         )
         yield* InstructionState.prepare(db, events, preparedInstructions, preparedSessionID)
       }

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

@@ -284,13 +284,9 @@ describe("Session.create", () => {
       })
       expect(yield* SessionPending.find(db, forkContext[0].id)).toBeUndefined()
       expect(yield* SessionPending.find(db, forkContext[1].id)).toBeUndefined()
-      // Fork-copied messages have no admitted event in the fork aggregate, so
-      // reusing their IDs as prompt IDs is conflicting reuse, not a retry.
       expect(
-        yield* session
+        yield* session.prompt({ id: forkContext[0].id, sessionID: forked.id, text: "First", resume: false }),
-          .prompt({ id: forkContext[0].id, sessionID: forked.id, text: "First", resume: false })
+      ).toMatchObject({ id: forkContext[0].id, type: "user", data: { text: "First" } })
-          .pipe(Effect.flip),
-      ).toMatchObject({ _tag: "Session.PromptConflictError", messageID: forkContext[0].id })
 
       yield* session.prompt({
         sessionID: parent.id,

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

@@ -110,4 +110,26 @@ describe("toSessionError", () => {
     expect(eligible.map(SessionRunnerRetry.isRetryable)).toEqual([true, true, true])
     expect(ineligible.map(SessionRunnerRetry.isRetryable)).toEqual([false, false, false, false, false, false, false])
   })
+
+  test("retries transport failures only when delivery is absent or not sent", () => {
+    const retryable = [
+      llm(new TransportReason({ message: "http transport" })),
+      llm(new TransportReason({ message: "connect failed", delivery: "not-sent", phase: "connect" })),
+    ]
+    const ineligible = [
+      llm(new TransportReason({ message: "send uncertain", delivery: "ambiguous", phase: "send" })),
+      llm(new TransportReason({ message: "response interrupted", delivery: "accepted", phase: "receive" })),
+      llm(
+        new TransportReason({
+          message: "continuation rejected",
+          delivery: "rejected",
+          recovery: "retry-full",
+          phase: "receive",
+        }),
+      ),
+    ]
+
+    expect(retryable.map(SessionRunnerRetry.isRetryable)).toEqual([true, true])
+    expect(ineligible.map(SessionRunnerRetry.isRetryable)).toEqual([false, false, false])
+  })
 })

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

@@ -553,6 +553,47 @@ describe("Session.prompt", () => {
     }),
   )
 
+  it.effect("reconciles an exact retry from the promoted message without admission history", () =>
+    Effect.gen(function* () {
+      yield* setup
+      const session = yield* Session.Service
+      const bus = yield* Bus.Service
+      const { db } = yield* Database.Service
+      const input = { sessionID, id: messageID, text: "Fix the failing tests", resume: false }
+      const first = yield* session.prompt(input)
+      yield* SessionPending.promote(db, bus, sessionID, "steer")
+      yield* db
+        .delete(EventTable)
+        .where(eq(EventTable.aggregate_id, sessionID))
+        .run()
+        .pipe(Effect.orDie)
+
+      const retried = yield* session.prompt(input)
+
+      expect(retried).toMatchObject({ id: first.id, type: "user", data: { text: first.data.text } })
+      expect(yield* session.messages({ sessionID })).toMatchObject([
+        { id: messageID, type: "user", text: "Fix the failing tests" },
+      ])
+    }),
+  )
+
+  it.effect("ignores delivery when retrying a promoted message", () =>
+    Effect.gen(function* () {
+      yield* setup
+      const session = yield* Session.Service
+      const bus = yield* Bus.Service
+      const { db } = yield* Database.Service
+      const input = { sessionID, id: messageID, text: "Fix the failing tests", resume: false }
+      yield* session.prompt(input)
+      yield* SessionPending.promote(db, bus, sessionID, "steer")
+
+      const retried = yield* session.prompt({ ...input, delivery: "queue" })
+
+      expect(retried).toMatchObject({ id: messageID, type: "user", data: { text: input.text } })
+      expect(yield* admitted(messageID)).toBeUndefined()
+    }),
+  )
+
   it.effect("wakes execution when an exact prompt retry recovers a committed message", () =>
     Effect.gen(function* () {
       yield* setup

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

@@ -1180,7 +1180,7 @@ describe("SessionRunnerLLM", () => {
     }),
   )
 
-  it.effect("forks instruction values at the selected message instead of the parent's latest state", () =>
+  it.effect("seeds a fork with the parent's newest instruction values", () =>
     Effect.gen(function* () {
       const session = yield* setup
       yield* runPrompt(session, "First")
@@ -1197,14 +1197,16 @@ describe("SessionRunnerLLM", () => {
           .where(eq(InstructionStateTable.session_id, forked.id))
           .get(),
       ).toMatchObject({
-        initial_values: { "test/context": Instructions.hash("Changed context") },
+        initial_values: { "test/context": Instructions.hash("Latest context") },
-        current_values: { "test/context": Instructions.hash("Changed context") },
+        current_values: { "test/context": Instructions.hash("Latest context") },
       })
       yield* session.prompt({ sessionID: forked.id, text: "Forked", resume: false })
       yield* session.resume(forked.id)
 
-      expect(requests.at(-1)?.system.map((part) => part.text)).toEqual([defaultSystem, "Changed context"])
+      expect(requests.at(-1)?.system.map((part) => part.text)).toEqual([defaultSystem, "Latest context"])
-      expect(systemTexts(requests.at(-1)!)).toContain("Latest context")
+      // Copied history keeps the frozen chronological update; no new update is emitted.
+      expect(systemTexts(requests.at(-1)!)).toContain("Changed context")
+      expect(systemTexts(requests.at(-1)!)).not.toContain("Latest context")
 
       const { db } = yield* Database.Service
       const bus = yield* Bus.Service
@@ -1263,7 +1265,7 @@ describe("SessionRunnerLLM", () => {
     }),
   )
 
-  it.effect("rebuilds a missing instruction cache without admitting another delta", () =>
+  it.effect("re-establishes a fresh baseline when instruction state is missing", () =>
     Effect.gen(function* () {
       const session = yield* setup
       const { db } = yield* Database.Service
@@ -1277,13 +1279,15 @@ describe("SessionRunnerLLM", () => {
       expect(requests).toHaveLength(1)
       expect(requests[0]?.system.map((part) => part.text)).toEqual([defaultSystem, "Initial context"])
       expect(messageRoles(requests[0])).toEqual(["user", "user"])
+      // The projected row is authoritative: a missing row admits a fresh baseline
+      // instead of rebuilding from durable events.
       expect(
         yield* db
-          .select({ id: EventTable.id })
+          .select({ data: EventTable.data })
           .from(EventTable)
           .where(eq(EventTable.type, "session.instructions.updated.2"))
           .all(),
-      ).toHaveLength(1)
+      ).toHaveLength(2)
       expect(yield* db.select().from(InstructionStateTable).get()).toMatchObject({
         initial_values: { "test/context": Instructions.hash("Initial context") },
         current_values: { "test/context": Instructions.hash("Initial context") },
@@ -1310,7 +1314,10 @@ describe("SessionRunnerLLM", () => {
       ])
       expect(messageRoles(requests[1])).toEqual(["user", "system", "user"])
       expect(requests[1]?.messages.at(1)?.content).toEqual([{ type: "text", text: "Changed context" }])
-      expect(yield* session.messages({ sessionID })).toHaveLength(2)
+      // The chronological update is a durable client-visible system message.
+      const messages = yield* session.messages({ sessionID })
+      expect(messages).toHaveLength(3)
+      expect(messages[1]).toMatchObject({ type: "system", text: "Changed context" })
       const { db } = yield* Database.Service
       const updates = yield* db
         .select({ data: EventTable.data })
@@ -1327,9 +1334,10 @@ describe("SessionRunnerLLM", () => {
       expect(updates[1]?.data).toEqual({
         sessionID,
         delta: { "test/context": Instructions.hash("Changed context") },
+        text: "Changed context",
       })
       yield* replaySessionProjection(sessionID)
-      expect(yield* session.messages({ sessionID })).toHaveLength(2)
+      expect(yield* session.messages({ sessionID })).toHaveLength(3)
     }),
   )
 
@@ -1596,7 +1604,7 @@ describe("SessionRunnerLLM", () => {
       expect(requests[1]?.messages.at(1)?.content).toEqual([
         { type: "text", text: "System context source removed: test/context" },
       ])
-      expect(yield* session.messages({ sessionID })).toHaveLength(2)
+      expect(yield* session.messages({ sessionID })).toHaveLength(3)
     }),
   )
 
@@ -1708,12 +1716,14 @@ describe("SessionRunnerLLM", () => {
       expect(requests[2]?.messages.filter((message) => message.role === "system")).toHaveLength(2)
       expect((yield* session.context(sessionID)).map((message) => message.type)).toEqual([
         "user",
+        "system",
         "user",
         "model-switched",
+        "system",
         "user",
       ])
       yield* replaySessionProjection(sessionID)
-      expect(yield* session.messages({ sessionID })).toHaveLength(4)
+      expect(yield* session.messages({ sessionID })).toHaveLength(6)
       yield* runPrompt(session, "Fourth")
     }),
   )

packages/schema/src/session-event.ts

@@ -186,6 +186,11 @@ export const InstructionsUpdated = Event.durable({
   schema: {
     ...Base,
     delta: Instruction.Delta,
+    /**
+     * The rendered chronological update shown to the model, frozen at emit time.
+     * Absent for the initial baseline observation and for deltas that render empty.
+     */
+    text: Schema.String.pipe(optional),
   },
 })
 export type InstructionsUpdated = typeof InstructionsUpdated.Type

packages/tui/test/cli/tui/diff-viewer.test.tsx

@@ -147,12 +147,12 @@ async function renderDiffViewer(vcsDiff: unknown[], height = 20, initialRoute?:
   const config = createTuiResolvedConfig()
   const transport = createFetch((url) => {
     if (url.pathname !== "/api/vcs/diff") return
-    if (fail) return json({ message: "boom" }, { status: 500 })
     vcsDiffInput = {
       location: { directory: url.searchParams.get("location[directory]") },
       mode: url.searchParams.get("mode"),
       context: url.searchParams.get("context"),
     }
+    if (fail) return json({ message: "boom" }, { status: 500 })
     return json({
       location: { directory: "/repo/session", project: { id: "project-1", directory: "/repo/session" } },
       data: vcsDiff,
@@ -238,6 +238,7 @@ async function renderDiffViewer(vcsDiff: unknown[], height = 20, initialRoute?:
 
   const app = await testRender(() => <Harness />, { width: 80, height })
   await waitForCommand(app, commands, "diff.close")
+  await app.waitFor(() => vcsDiffInput !== undefined)
   return {
     app,
     commands,