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

import { describe, expect } from "bun:test"
import {
  LLMClient,
  LLMError,
  LLMEvent,
  Model,
  Tool,
  TransportReason,
  type LLMClientShape,
  type LLMRequest,
} from "@opencode-ai/llm"
import * as OpenAIChat from "@opencode-ai/llm/protocols/openai-chat"
import { Database } from "@opencode-ai/core/database/database"
import { EventV2 } from "@opencode-ai/core/event"
import { PermissionV2 } from "@opencode-ai/core/permission"
import { EventTable } from "@opencode-ai/core/event/sql"
import { Project } from "@opencode-ai/core/project"
import { ProjectTable } from "@opencode-ai/core/project/sql"
import { QuestionV2 } from "@opencode-ai/core/question"
import { AbsolutePath } from "@opencode-ai/core/schema"
import { SessionV2 } from "@opencode-ai/core/session"
import { ContextSnapshotDecodeError } from "@opencode-ai/core/session/error"
import { SessionEvent } from "@opencode-ai/core/session/event"
import { SessionInput } from "@opencode-ai/core/session/input"
import { SessionMessage } from "@opencode-ai/core/session/message"
import { Prompt } from "@opencode-ai/core/session/prompt"
import { SessionProjector } from "@opencode-ai/core/session/projector"
import { SessionExecution } from "@opencode-ai/core/session/execution"
import { SessionContextEpoch } from "@opencode-ai/core/session/context-epoch"
import { SessionRunCoordinator } from "@opencode-ai/core/session/run-coordinator"
import { SessionRunner } from "@opencode-ai/core/session/runner"
import * as SessionRunnerLLM from "@opencode-ai/core/session/runner/llm"
import { SessionRunnerModel } from "@opencode-ai/core/session/runner/model"
import { ToolRegistry } from "@opencode-ai/core/tool/registry"
import { ApplicationTools } from "@opencode-ai/core/tool/application-tools"
import { AgentV2 } from "@opencode-ai/core/agent"
import { NativeTool } from "@opencode-ai/core/tool/native"
import {
  SessionContextEpochTable,
  SessionInputTable,
  SessionMessageTable,
  SessionTable,
} from "@opencode-ai/core/session/sql"
import { SessionStore } from "@opencode-ai/core/session/store"
import { SystemContext } from "@opencode-ai/core/system-context"
import { SystemContextRegistry } from "@opencode-ai/core/system-context/registry"
import { SkillGuidance } from "@opencode-ai/core/skill/guidance"
import { ModelV2 } from "@opencode-ai/core/model"
import { Location } from "@opencode-ai/core/location"
import { ProviderV2 } from "@opencode-ai/core/provider"
import { Cause, DateTime, Deferred, Effect, Exit, Fiber, Layer, Schema, Stream } from "effect"
import { asc, eq } from "drizzle-orm"
import { testEffect } from "./lib/effect"

const database = Database.layerFromPath(":memory:")
const events = EventV2.layer.pipe(Layer.provide(database))
const questions = QuestionV2.layer.pipe(Layer.provide(events))
const projector = SessionProjector.layer.pipe(Layer.provide(events), Layer.provide(database))
const store = SessionStore.layer.pipe(Layer.provide(database))
const requests: LLMRequest[] = []
let response: LLMEvent[] = []
let responses: LLMEvent[][] | undefined
let responseStream: Stream.Stream<LLMEvent, LLMError> | undefined
let streamGate: Deferred.Deferred<void> | undefined
let streamStarted: Deferred.Deferred<void> | undefined
let streamFailure: LLMError | undefined
let toolExecutionGate: Deferred.Deferred<void> | undefined
let toolExecutionsStarted: Deferred.Deferred<void> | undefined
let toolExecutionsReady = 5
let activeToolExecutions = 0
let maxActiveToolExecutions = 0
const client = Layer.succeed(
  LLMClient.Service,
  LLMClient.Service.of({
    prepare: () => Effect.die("unused"),
    stream: ((request: LLMRequest) => {
      requests.push(request)
      if (responseStream) {
        const stream = responseStream
        responseStream = undefined
        return stream
      }
      const events = streamFailure
        ? Stream.fail(streamFailure)
        : Stream.fromIterable(responses === undefined ? response : (responses.shift() ?? []))
      if (!streamGate) return events
      return Stream.unwrap(
        (streamStarted ? Deferred.succeed(streamStarted, undefined) : Effect.void).pipe(
          Effect.andThen(Deferred.await(streamGate)),
          Effect.as(events),
        ),
      )
    }) as unknown as LLMClientShape["stream"],
    generate: () => Effect.die("unused"),
  }),
)
const model = Model.make({ id: "fake-model", provider: "fake", route: OpenAIChat.route })
const replacementModel = Model.make({ id: "replacement", provider: "fake", route: OpenAIChat.route })
const authorizations: ToolRegistry.AuthorizeInput[] = []
const executions: string[] = []
const permission = Layer.succeed(
  PermissionV2.Service,
  PermissionV2.Service.of({
    assert: () => Effect.die("unused"),
    ask: () => Effect.die("unused"),
    reply: () => Effect.die("unused"),
    get: () => Effect.die("unused"),
    forSession: () => Effect.die("unused"),
    list: () => Effect.die("unused"),
  }),
)
const applications = ApplicationTools.layer
const registry = ToolRegistry.layer.pipe(Layer.provide(permission), Layer.provide(applications))
const agents = AgentV2.layer
const echo = Layer.effectDiscard(
  ToolRegistry.Service.use((registry) =>
    registry.contribute((editor) => {
      ;(editor.set("echo", {
        authorize: (input) =>
          Effect.sync(() => {
            authorizations.push(input)
          }),
        tool: Tool.make({
          description: "Echo text",
          parameters: Schema.Struct({ text: Schema.String }),
          success: Schema.Struct({ text: Schema.String }),
          toModelOutput: ({ output }) => [{ type: "text", text: output.text }],
          execute: ({ text }) =>
            Effect.gen(function* () {
              executions.push(text)
              activeToolExecutions++
              maxActiveToolExecutions = Math.max(maxActiveToolExecutions, activeToolExecutions)
              if (activeToolExecutions === toolExecutionsReady && toolExecutionsStarted) {
                yield* Deferred.succeed(toolExecutionsStarted, undefined)
              }
              if (toolExecutionGate) yield* Deferred.await(toolExecutionGate)
              return { text }
            }).pipe(Effect.ensuring(Effect.sync(() => activeToolExecutions--))),
        }),
      }),
        editor.set("defect", {
          tool: Tool.make({
            description: "Fail unexpectedly",
            parameters: Schema.Struct({}),
            success: Schema.Struct({}),
            execute: () => Effect.die("unexpected tool defect"),
          }),
        }))
    }),
  ),
).pipe(Layer.provide(registry))
let modelResolveHook = Effect.void
const models = SessionRunnerModel.layerWith((session) =>
  modelResolveHook.pipe(Effect.as(session.model?.id === "replacement" ? replacementModel : model)),
)
const systemContextKey = SystemContext.Key.make("test/context")
let systemBaseline = "Initial context"
let systemRemoved = false
let systemUnavailable = false
let systemLoadHook = Effect.void
const skillBaselines = new Map<AgentV2.ID, string>()
const systemContext = Layer.effectDiscard(
  SystemContextRegistry.Service.pipe(
    Effect.flatMap((registry) =>
      registry.contribute({
        key: systemContextKey,
        load: Effect.sync(() =>
          SystemContext.combine(
            systemRemoved
              ? []
              : [
                  SystemContext.make({
                    key: systemContextKey,
                    codec: Schema.toCodecJson(Schema.String),
                    load: systemLoadHook.pipe(
                      Effect.andThen(
                        Effect.sync(() => (systemUnavailable ? SystemContext.unavailable : systemBaseline)),
                      ),
                    ),
                    baseline: String,
                    update: (_previous, current) => current,
                    removed: () => "System context source removed: test/context",
                  }),
                ],
          ),
        ),
      }),
    ),
  ),
).pipe(Layer.provideMerge(SystemContextRegistry.layer))
const location = Location.layer({ directory: AbsolutePath.make("/project") }).pipe(Layer.provide(Project.defaultLayer))
const skillGuidance = Layer.mock(SkillGuidance.Service, {
  load: (agent) =>
    Effect.succeed(
      skillBaselines.has(agent.id)
        ? SystemContext.make({
            key: SystemContext.Key.make("test/skill-guidance"),
            codec: Schema.toCodecJson(Schema.String),
            load: Effect.succeed(skillBaselines.get(agent.id)!),
            baseline: String,
            update: (_previous, current) => current,
            removed: () => "Skill guidance removed",
          })
        : SystemContext.empty,
    ),
})
const runner = SessionRunnerLLM.layer.pipe(
  Layer.provide(database),
  Layer.provide(store),
  Layer.provide(events),
  Layer.provide(client),
  Layer.provide(registry),
  Layer.provide(models),
  Layer.provide(systemContext),
  Layer.provide(location),
  Layer.provide(agents),
  Layer.provide(skillGuidance),
)
const coordinator = SessionRunCoordinator.layer.pipe(Layer.provide(runner))
const execution = Layer.effect(
  SessionExecution.Service,
  SessionRunCoordinator.Service.pipe(
    Effect.map((coordinator) =>
      SessionExecution.Service.of({
        resume: coordinator.run,
        wake: coordinator.wake,
        interrupt: coordinator.interrupt,
      }),
    ),
  ),
).pipe(Layer.provide(coordinator))
const sessions = SessionV2.layer.pipe(
  Layer.provide(events),
  Layer.provide(database),
  Layer.provide(store),
  Layer.provide(Project.defaultLayer),
  Layer.provide(execution),
)
const it = testEffect(
  Layer.mergeAll(
    database,
    events,
    questions,
    projector,
    store,
    client,
    permission,
    applications,
    agents,
    registry,
    echo,
    models,
    systemContext,
    location,
    skillGuidance,
    runner,
    coordinator,
    execution,
    sessions,
  ),
)
const sessionID = SessionV2.ID.make("ses_runner_test")
const otherSessionID = SessionV2.ID.make("ses_runner_other")

const insertSession = (id: SessionV2.ID) =>
  Effect.gen(function* () {
    const { db } = yield* Database.Service
    yield* db
      .insert(SessionTable)
      .values({
        id,
        project_id: Project.ID.global,
        slug: id,
        directory: "/project",
        title: "test",
        version: "test",
      })
      .onConflictDoNothing()
      .run()
      .pipe(Effect.orDie)
  })

const setup = Effect.gen(function* () {
  const { db } = yield* Database.Service
  response = []
  systemBaseline = "Initial context"
  systemRemoved = false
  systemUnavailable = false
  systemLoadHook = Effect.void
  modelResolveHook = Effect.void
  skillBaselines.clear()
  responses = undefined
  streamFailure = undefined
  responseStream = undefined
  streamGate = undefined
  streamStarted = undefined
  toolExecutionGate = undefined
  toolExecutionsStarted = undefined
  toolExecutionsReady = 5
  activeToolExecutions = 0
  maxActiveToolExecutions = 0
  yield* db
    .insert(ProjectTable)
    .values({ id: Project.ID.global, worktree: AbsolutePath.make("/project"), sandboxes: [] })
    .onConflictDoNothing()
    .run()
    .pipe(Effect.orDie)
  yield* insertSession(sessionID)
})

const providerUnavailable = () =>
  new LLMError({
    module: "test",
    method: "stream",
    reason: new TransportReason({ message: "Provider unavailable" }),
  })

const userTexts = (request: LLMRequest) =>
  request.messages.flatMap((message) =>
    message.role === "user"
      ? message.content.flatMap((content) => (content.type === "text" ? [content.text] : []))
      : [],
  )

const replaySessionProjection = (id: SessionV2.ID) =>
  Effect.gen(function* () {
    const { db } = yield* Database.Service
    const events = yield* EventV2.Service
    const recorded = yield* db
      .select()
      .from(EventTable)
      .where(eq(EventTable.aggregate_id, id))
      .orderBy(asc(EventTable.seq))
      .all()
      .pipe(Effect.orDie)

    yield* events.remove(id)
    yield* db.delete(SessionInputTable).where(eq(SessionInputTable.session_id, id)).run().pipe(Effect.orDie)
    yield* db.delete(SessionMessageTable).where(eq(SessionMessageTable.session_id, id)).run().pipe(Effect.orDie)
    yield* events.replayAll(
      recorded.map((event) => ({
        id: event.id,
        aggregateID: event.aggregate_id,
        seq: event.seq,
        type: event.type,
        data: event.data,
      })),
    )
  })

type FragmentKind = "text" | "reasoning" | "tool input"

type FragmentFixture = {
  readonly delta: EventV2.Definition
  readonly completeEvents: LLMEvent[]
  readonly partialEvents: LLMEvent[]
  readonly expectedAssistant: unknown
  readonly expectedContent: unknown
}

const fragmentKinds: readonly FragmentKind[] = ["text", "reasoning", "tool input"]

const fragmentID = (kind: FragmentKind, suffix: string) => `${kind === "tool input" ? "call" : kind}-${suffix}`

const fragmentFixture = (kind: FragmentKind, id: string, chunks: readonly string[]): FragmentFixture => {
  const text = chunks.join("")
  switch (kind) {
    case "text": {
      const partialEvents = [
        LLMEvent.stepStart({ index: 0 }),
        LLMEvent.textStart({ id }),
        ...chunks.map((text) => LLMEvent.textDelta({ id, text })),
      ]
      const expectedContent = { type: "text", id, text }
      return {
        delta: SessionEvent.Text.Delta,
        partialEvents,
        completeEvents: [
          ...partialEvents,
          LLMEvent.textEnd({ id }),
          LLMEvent.stepFinish({ index: 0, reason: "stop" }),
          LLMEvent.finish({ reason: "stop" }),
        ],
        expectedAssistant: { type: "assistant", finish: "stop", content: [expectedContent] },
        expectedContent,
      }
    }
    case "reasoning": {
      const partialEvents = [
        LLMEvent.stepStart({ index: 0 }),
        LLMEvent.reasoningStart({ id }),
        ...chunks.map((text) => LLMEvent.reasoningDelta({ id, text })),
      ]
      const expectedContent = { type: "reasoning", id, text }
      return {
        delta: SessionEvent.Reasoning.Delta,
        partialEvents,
        completeEvents: [
          ...partialEvents,
          LLMEvent.reasoningEnd({ id }),
          LLMEvent.stepFinish({ index: 0, reason: "stop" }),
          LLMEvent.finish({ reason: "stop" }),
        ],
        expectedAssistant: { type: "assistant", finish: "stop", content: [expectedContent] },
        expectedContent,
      }
    }
    case "tool input": {
      const partialEvents = [
        LLMEvent.stepStart({ index: 0 }),
        LLMEvent.toolInputStart({ id, name: "echo" }),
        ...chunks.map((text) => LLMEvent.toolInputDelta({ id, name: "echo", text })),
      ]
      const expectedContent = { type: "tool", id, state: { status: "pending", input: text } }
      return {
        delta: SessionEvent.Tool.Input.Delta,
        partialEvents,
        completeEvents: [...partialEvents, LLMEvent.toolInputEnd({ id, name: "echo" })],
        expectedAssistant: { type: "assistant", content: [expectedContent] },
        expectedContent,
      }
    }
  }
}

const verifyEphemeralDeltas = (kind: FragmentKind) =>
  Effect.gen(function* () {
    yield* setup
    const session = yield* SessionV2.Service
    const prompt = `Stream ${kind}`
    const chunks = Array.from({ length: 32 }, (_, index) => `${index},`)
    const fixture = fragmentFixture(kind, fragmentID(kind, "many"), chunks)
    const expectedContext = [{ type: "user", text: prompt }, fixture.expectedAssistant]
    yield* session.prompt({ sessionID, prompt: new Prompt({ text: prompt }), resume: false })
    const events = yield* EventV2.Service
    const live = yield* events.subscribe(fixture.delta).pipe(Stream.take(32), Stream.runCollect, Effect.forkScoped)
    yield* Effect.yieldNow
    response = fixture.completeEvents

    yield* session.resume(sessionID)

    const { db } = yield* Database.Service
    const deltas = yield* db
      .select({ type: EventTable.type })
      .from(EventTable)
      .where(eq(EventTable.type, EventV2.versionedType(fixture.delta.type, 1)))
      .all()
      .pipe(Effect.orDie)
    expect(Array.from(yield* Fiber.join(live))).toHaveLength(32)
    expect(deltas).toHaveLength(0)
    expect(yield* session.context(sessionID)).toMatchObject(expectedContext)

    yield* replaySessionProjection(sessionID)

    expect(yield* session.context(sessionID)).toMatchObject(expectedContext)
  })

const verifyPartialFlushOnFailure = (kind: FragmentKind) =>
  Effect.gen(function* () {
    yield* setup
    const session = yield* SessionV2.Service
    const prompt = `Fail after ${kind}`
    const fixture = fragmentFixture(kind, fragmentID(kind, "partial"), ["Partial"])
    const failure = providerUnavailable()
    yield* session.prompt({ sessionID, prompt: new Prompt({ text: prompt }), resume: false })
    responseStream = Stream.concat(Stream.fromIterable(fixture.partialEvents), Stream.fail(failure))

    expect(yield* session.resume(sessionID).pipe(Effect.flip)).toBe(failure)
    expect(yield* session.context(sessionID)).toMatchObject([
      { type: "user", text: prompt },
      {
        type: "assistant",
        finish: "error",
        error: { type: "unknown", message: "Provider unavailable" },
        content: [fixture.expectedContent],
      },
    ])
  })

const verifyPartialFlushOnInterruption = (kind: FragmentKind) =>
  Effect.gen(function* () {
    yield* setup
    const session = yield* SessionV2.Service
    const prompt = `Interrupt after ${kind}`
    const fixture = fragmentFixture(kind, fragmentID(kind, "interrupted"), ["Partial"])
    const streamed = yield* Deferred.make<void>()
    yield* session.prompt({ sessionID, prompt: new Prompt({ text: prompt }), resume: false })
    responseStream = Stream.concat(
      Stream.fromIterable(fixture.partialEvents),
      Stream.fromEffect(Deferred.succeed(streamed, undefined)).pipe(Stream.flatMap(() => Stream.never)),
    )

    const runner = yield* SessionRunner.Service
    const fiber = yield* runner.run({ sessionID, force: true }).pipe(Effect.forkChild)
    yield* Deferred.await(streamed)
    yield* Fiber.interrupt(fiber)
    expect(yield* session.context(sessionID)).toMatchObject([
      { type: "user", text: prompt },
      {
        type: "assistant",
        content: [
          kind === "tool input"
            ? { type: "tool", id: fragmentID(kind, "interrupted"), state: { status: "error" } }
            : fixture.expectedContent,
        ],
      },
    ])
  })

describe("SessionRunnerLLM", () => {
  it.effect("advertises and executes a globally attached application tool", () =>
    Effect.gen(function* () {
      yield* setup
      const applicationTools = yield* ApplicationTools.Service
      const session = yield* SessionV2.Service
      const contexts: NativeTool.Context[] = []
      yield* applicationTools.attach({
        application_context: NativeTool.make({
          description: "Read application context",
          parameters: Schema.Struct({ query: Schema.String }),
          success: Schema.Struct({ answer: Schema.String }),
          execute: ({ query }, context) =>
            Effect.sync(() => {
              contexts.push(context)
              return { answer: query.toUpperCase() }
            }),
        }),
      })
      yield* session.prompt({ sessionID, prompt: new Prompt({ text: "Use application context" }), resume: false })
      responses = [
        [
          LLMEvent.stepStart({ index: 0 }),
          LLMEvent.toolCall({ id: "call-application", name: "application_context", input: { query: "hello" } }),
          LLMEvent.stepFinish({ index: 0, reason: "tool-calls" }),
          LLMEvent.finish({ reason: "tool-calls" }),
        ],
        [],
      ]

      yield* session.resume(sessionID)

      expect(requests[0]?.tools.map((tool) => tool.name)).toContain("application_context")
      expect(contexts).toEqual([{ sessionID, id: "call-application", name: "application_context" }])
      expect(yield* session.context(sessionID)).toMatchObject([
        { type: "user", text: "Use application context" },
        {
          type: "assistant",
          content: [
            {
              type: "tool",
              id: "call-application",
              state: { status: "completed", structured: { answer: "HELLO" } },
            },
          ],
        },
      ])
    }),
  )

  it.effect("starts a real runner turn after default prompt recording", () =>
    Effect.gen(function* () {
      yield* setup
      const session = yield* SessionV2.Service
      requests.length = 0
      responses = undefined
      streamGate = undefined
      streamStarted = undefined
      response = []

      const message = yield* session.prompt({ sessionID, prompt: new Prompt({ text: "Run automatically" }) })

      expect(requests).toHaveLength(1)
      expect(yield* session.messages({ sessionID })).toMatchObject([
        { id: message.id, type: "user", text: "Run automatically" },
      ])
    }),
  )

  it.effect("streams one request with registry definitions from chronological V2 user history", () =>
    Effect.gen(function* () {
      yield* setup
      const session = yield* SessionV2.Service
      yield* session.prompt({ sessionID, prompt: new Prompt({ text: "First" }), resume: false })
      yield* session.prompt({ sessionID, prompt: new Prompt({ text: "Second" }), resume: false })

      requests.length = 0
      responses = undefined
      streamGate = undefined
      streamStarted = undefined
      response = []
      yield* session.resume(sessionID)

      expect(requests).toHaveLength(1)
      expect(requests[0]?.model).toBe(model)
      expect(requests[0]?.tools.map((tool) => tool.name)).toEqual(["echo", "defect"])
      expect(requests[0]?.messages.map((message) => ({ role: message.role, content: message.content }))).toEqual([
        { role: "user", content: [{ type: "text", text: "First" }] },
        { role: "user", content: [{ type: "text", text: "Second" }] },
      ])
      expect(yield* session.messages({ sessionID })).toHaveLength(2)
    }),
  )

  it.effect("retries the first provider turn after system context becomes available", () =>
    Effect.gen(function* () {
      yield* setup
      const session = yield* SessionV2.Service
      const { db } = yield* Database.Service
      const messageID = SessionMessage.ID.create()
      systemUnavailable = true
      yield* session.prompt({ id: messageID, sessionID, prompt: new Prompt({ text: "First" }), resume: false })
      requests.length = 0

      const exit = yield* session.resume(sessionID).pipe(Effect.exit)

      expect(Exit.isFailure(exit)).toBe(true)
      if (Exit.isFailure(exit)) expect(Cause.squash(exit.cause)).toBeInstanceOf(SystemContext.InitializationBlocked)
      expect(requests).toHaveLength(0)
      expect(yield* SessionInput.hasPending(db, sessionID, "steer")).toBe(true)
      expect(
        yield* db
          .select()
          .from(SessionContextEpochTable)
          .where(eq(SessionContextEpochTable.session_id, sessionID))
          .get(),
      ).toBeUndefined()

      systemUnavailable = false
      yield* session.prompt({ id: messageID, sessionID, prompt: new Prompt({ text: "First" }) })
      yield* (yield* SessionRunCoordinator.Service).awaitIdle(sessionID)

      expect(requests).toHaveLength(1)
      expect(requests[0]?.messages.map((message) => message.role)).toEqual(["user"])
    }),
  )

  it.effect("interrupts a source Location runner after a Session moves", () =>
    Effect.gen(function* () {
      yield* setup
      const session = yield* SessionV2.Service
      const events = yield* EventV2.Service
      const { db } = yield* Database.Service
      yield* session.prompt({ sessionID, prompt: new Prompt({ text: "First" }), resume: false })
      requests.length = 0
      response = []
      yield* session.resume(sessionID)

      yield* events.publish(SessionEvent.Moved, {
        sessionID,
        timestamp: DateTime.makeUnsafe(1),
        location: { directory: AbsolutePath.make("/moved") },
      })
      expect(
        yield* db
          .select()
          .from(SessionContextEpochTable)
          .where(eq(SessionContextEpochTable.session_id, sessionID))
          .get(),
      ).toBeUndefined()

      yield* session.prompt({ sessionID, prompt: new Prompt({ text: "Second" }), resume: false })
      const exit = yield* session.resume(sessionID).pipe(Effect.exit)

      expect(Exit.isFailure(exit) && Cause.hasInterruptsOnly(exit.cause)).toBe(true)
      expect(requests).toHaveLength(1)
      expect(yield* SessionInput.hasPending(db, sessionID, "steer")).toBe(true)
    }),
  )

  it.effect("fails gracefully when a stored context snapshot cannot be decoded", () =>
    Effect.gen(function* () {
      yield* setup
      const session = yield* SessionV2.Service
      const { db } = yield* Database.Service
      yield* session.prompt({ sessionID, prompt: new Prompt({ text: "First" }), resume: false })
      response = []
      yield* session.resume(sessionID)
      yield* db
        .update(SessionContextEpochTable)
        .set({ snapshot: { invalid: { value: "bad" } } })
        .where(eq(SessionContextEpochTable.session_id, sessionID))
        .run()
        .pipe(Effect.orDie)
      yield* session.prompt({ sessionID, prompt: new Prompt({ text: "Second" }), resume: false })
      requests.length = 0

      const exit = yield* session.resume(sessionID).pipe(Effect.exit)

      expect(Exit.isFailure(exit)).toBe(true)
      if (Exit.isFailure(exit)) expect(Cause.squash(exit.cause)).toBeInstanceOf(ContextSnapshotDecodeError)
      expect(requests).toHaveLength(0)
    }),
  )

  it.effect("does not create a source Location epoch after a concurrent Session move", () =>
    Effect.gen(function* () {
      yield* setup
      const session = yield* SessionV2.Service
      const events = yield* EventV2.Service
      const { db } = yield* Database.Service
      let moved = false
      systemLoadHook = Effect.suspend(() => {
        if (moved) return Effect.void
        moved = true
        return events
          .publish(SessionEvent.Moved, {
            sessionID,
            timestamp: DateTime.makeUnsafe(1),
            location: { directory: AbsolutePath.make("/moved") },
          })
          .pipe(Effect.asVoid)
      })
      yield* session.prompt({ sessionID, prompt: new Prompt({ text: "First" }), resume: false })

      expect(Exit.isFailure(yield* session.resume(sessionID).pipe(Effect.exit))).toBe(true)
      expect(yield* SessionInput.hasPending(db, sessionID, "steer")).toBe(true)
      expect(
        yield* db
          .select()
          .from(SessionContextEpochTable)
          .where(eq(SessionContextEpochTable.session_id, sessionID))
          .get(),
      ).toBeUndefined()
      expect((yield* session.get(sessionID)).location.directory).toBe(AbsolutePath.make("/moved"))
    }),
  )

  it.effect("reuses one durable baseline after the context producer changes", () =>
    Effect.gen(function* () {
      yield* setup
      const session = yield* SessionV2.Service
      yield* session.prompt({ sessionID, prompt: new Prompt({ text: "First" }), resume: false })

      requests.length = 0
      response = []
      yield* session.resume(sessionID)
      systemBaseline = "Changed context"
      yield* session.prompt({ sessionID, prompt: new Prompt({ text: "Second" }), resume: false })
      yield* session.resume(sessionID)

      expect(requests.map((request) => request.system.map((part) => part.text))).toEqual([
        ["Initial context"],
        ["Initial context"],
      ])
      expect(requests[1]?.messages.map((message) => message.role)).toEqual(["user", "user", "system"])
      expect(requests[1]?.messages.at(-1)?.content).toEqual([{ type: "text", text: "Changed context" }])
      expect(yield* session.messages({ sessionID })).toHaveLength(3)
      const { db } = yield* Database.Service
      expect(
        yield* db
          .select({ id: EventTable.id })
          .from(EventTable)
          .where(eq(EventTable.type, "session.next.context.updated.1"))
          .all()
          .pipe(Effect.orDie),
      ).toHaveLength(1)
      yield* replaySessionProjection(sessionID)
      expect(yield* session.messages({ sessionID })).toHaveLength(3)
    }),
  )

  it.effect("includes the effective default agent system before durable context", () =>
    Effect.gen(function* () {
      yield* setup
      const agent = yield* AgentV2.Service
      yield* agent.update((editor) =>
        editor.update(AgentV2.ID.make("build"), (agent) => {
          agent.system = "Build agent instructions"
          agent.mode = "primary"
        }),
      )
      const session = yield* SessionV2.Service
      yield* session.prompt({ sessionID, prompt: new Prompt({ text: "First" }), resume: false })

      requests.length = 0
      response = fragmentFixture("text", "text-build", ["Done"]).completeEvents
      yield* session.resume(sessionID)

      expect(requests.at(-1)?.system.map((part) => part.text)).toEqual(["Build agent instructions", "Initial context"])
    }),
  )

  it.effect("uses the configured default agent system for omitted-agent sessions", () =>
    Effect.gen(function* () {
      yield* setup
      const agent = yield* AgentV2.Service
      yield* agent.update((editor) => {
        editor.update(AgentV2.ID.make("build"), (agent) => {
          agent.system = "Build agent instructions"
          agent.mode = "primary"
        })
        editor.update(AgentV2.ID.make("reviewer"), (agent) => {
          agent.system = "Reviewer instructions"
          agent.mode = "primary"
        })
        editor.default(AgentV2.ID.make("reviewer"))
      })
      const session = yield* SessionV2.Service
      yield* session.prompt({ sessionID, prompt: new Prompt({ text: "First" }), resume: false })

      requests.length = 0
      response = fragmentFixture("text", "text-reviewer", ["Done"]).completeEvents
      yield* session.resume(sessionID)

      expect(requests.at(-1)?.system.map((part) => part.text)).toEqual(["Reviewer instructions", "Initial context"])
      expect((yield* session.messages({ sessionID }))[0]).toMatchObject({ type: "assistant", agent: "reviewer" })
    }),
  )

  it.effect("uses an explicitly selected non-build agent system", () =>
    Effect.gen(function* () {
      yield* setup
      const { db } = yield* Database.Service
      const agent = yield* AgentV2.Service
      yield* agent.update((editor) =>
        editor.update(AgentV2.ID.make("reviewer"), (agent) => {
          agent.system = "Reviewer instructions"
          agent.mode = "primary"
        }),
      )
      yield* db
        .update(SessionTable)
        .set({ agent: "reviewer" })
        .where(eq(SessionTable.id, sessionID))
        .run()
        .pipe(Effect.orDie)
      const session = yield* SessionV2.Service
      yield* session.prompt({ sessionID, prompt: new Prompt({ text: "First" }), resume: false })

      requests.length = 0
      response = fragmentFixture("text", "text-selected", ["Done"]).completeEvents
      yield* session.resume(sessionID)

      expect(requests.at(-1)?.system.map((part) => part.text)).toEqual(["Reviewer instructions", "Initial context"])
      expect((yield* session.messages({ sessionID }))[0]).toMatchObject({ type: "assistant", agent: "reviewer" })
    }),
  )

  it.effect("composes selected-agent skill guidance and replaces it after an agent switch", () =>
    Effect.gen(function* () {
      yield* setup
      const session = yield* SessionV2.Service
      const events = yield* EventV2.Service
      skillBaselines.set(AgentV2.ID.make("build"), "Build skills")
      yield* session.prompt({ sessionID, prompt: new Prompt({ text: "First" }), resume: false })

      requests.length = 0
      response = []
      yield* session.resume(sessionID)
      skillBaselines.set(AgentV2.ID.make("reviewer"), "Reviewer skills")
      yield* events.publish(SessionEvent.AgentSwitched, {
        sessionID,
        messageID: SessionMessage.ID.create(),
        timestamp: DateTime.makeUnsafe(1),
        agent: "reviewer",
      })
      yield* session.prompt({ sessionID, prompt: new Prompt({ text: "Second" }), resume: false })
      yield* session.resume(sessionID)

      expect(requests.map((request) => request.system.map((part) => part.text))).toEqual([
        ["Initial context\n\nBuild skills"],
        ["Initial context\n\nReviewer skills"],
      ])
    }),
  )

  it.effect("retries first-epoch preparation when the selected agent changes during observation", () =>
    Effect.gen(function* () {
      yield* setup
      const session = yield* SessionV2.Service
      const events = yield* EventV2.Service
      skillBaselines.set(AgentV2.ID.make("build"), "Build skills")
      skillBaselines.set(AgentV2.ID.make("reviewer"), "Reviewer skills")
      let switched = false
      systemLoadHook = Effect.suspend(() => {
        if (switched) return Effect.void
        switched = true
        return events
          .publish(SessionEvent.AgentSwitched, {
            sessionID,
            messageID: SessionMessage.ID.create(),
            timestamp: DateTime.makeUnsafe(1),
            agent: "reviewer",
          })
          .pipe(Effect.asVoid)
      })
      yield* session.prompt({ sessionID, prompt: new Prompt({ text: "First" }), resume: false })

      requests.length = 0
      response = []
      yield* session.resume(sessionID)

      expect(requests.map((request) => request.system.map((part) => part.text))).toEqual([
        ["Initial context\n\nReviewer skills"],
      ])
    }),
  )

  it.effect("opens a queued activity once when the selected agent changes during observation", () =>
    Effect.gen(function* () {
      yield* setup
      const session = yield* SessionV2.Service
      const events = yield* EventV2.Service
      skillBaselines.set(AgentV2.ID.make("build"), "Build skills")
      skillBaselines.set(AgentV2.ID.make("reviewer"), "Reviewer skills")
      let switched = false
      systemLoadHook = Effect.suspend(() => {
        if (switched) return Effect.void
        switched = true
        return events
          .publish(SessionEvent.AgentSwitched, {
            sessionID,
            messageID: SessionMessage.ID.create(),
            timestamp: DateTime.makeUnsafe(1),
            agent: "reviewer",
          })
          .pipe(Effect.asVoid)
      })
      yield* session.prompt({
        sessionID,
        prompt: new Prompt({ text: "Queued" }),
        delivery: "queue",
        resume: false,
      })

      requests.length = 0
      response = []
      yield* session.resume(sessionID)

      expect(requests).toHaveLength(1)
      expect((yield* session.context(sessionID)).filter((message) => message.type === "user")).toHaveLength(1)
    }),
  )

  it.effect("retries an agent switch before the final provider-dispatch boundary", () =>
    Effect.gen(function* () {
      yield* setup
      const session = yield* SessionV2.Service
      const events = yield* EventV2.Service
      const { db } = yield* Database.Service
      skillBaselines.set(AgentV2.ID.make("build"), "Build skills")
      skillBaselines.set(AgentV2.ID.make("reviewer"), "Reviewer skills")
      let switched = false
      modelResolveHook = Effect.suspend(() => {
        if (switched) return Effect.void
        switched = true
        return events
          .publish(SessionEvent.AgentSwitched, {
            sessionID,
            messageID: SessionMessage.ID.create(),
            timestamp: DateTime.makeUnsafe(1),
            agent: "reviewer",
          })
          .pipe(Effect.asVoid)
      })
      yield* session.prompt({ sessionID, prompt: new Prompt({ text: "First" }), resume: false })

      requests.length = 0
      response = []
      yield* session.resume(sessionID)
      expect(requests.map((request) => request.system.map((part) => part.text))).toEqual([
        ["Initial context\n\nReviewer skills"],
      ])
      expect(
        yield* db
          .select({ replacementSeq: SessionContextEpochTable.replacement_seq })
          .from(SessionContextEpochTable)
          .where(eq(SessionContextEpochTable.session_id, sessionID))
          .get()
          .pipe(Effect.orDie),
      ).toEqual({ replacementSeq: null })
    }),
  )

  it.effect("retries a model switch before the final provider-dispatch boundary", () =>
    Effect.gen(function* () {
      yield* setup
      const session = yield* SessionV2.Service
      const events = yield* EventV2.Service
      let switched = false
      modelResolveHook = Effect.suspend(() => {
        if (switched) return Effect.void
        switched = true
        return events
          .publish(SessionEvent.ModelSwitched, {
            sessionID,
            messageID: SessionMessage.ID.create(),
            timestamp: DateTime.makeUnsafe(1),
            model: { id: ModelV2.ID.make("replacement"), providerID: ProviderV2.ID.make("fake") },
          })
          .pipe(Effect.asVoid)
      })
      yield* session.prompt({ sessionID, prompt: new Prompt({ text: "First" }), resume: false })

      requests.length = 0
      response = []
      yield* session.resume(sessionID)
      expect(requests.map((request) => request.model)).toEqual([replacementModel])
      expect(requests.map((request) => request.system.map((part) => part.text))).toEqual([["Initial context"]])
    }),
  )

  it.effect("fences an unchanged epoch read across an agent ABA replacement request", () =>
    Effect.gen(function* () {
      yield* setup
      const session = yield* SessionV2.Service
      const events = yield* EventV2.Service
      const { db } = yield* Database.Service
      yield* session.prompt({ sessionID, prompt: new Prompt({ text: "First" }), resume: false })
      response = []
      yield* session.resume(sessionID)
      let switched = false
      systemLoadHook = Effect.suspend(() => {
        if (switched) return Effect.void
        switched = true
        return events
          .publish(SessionEvent.AgentSwitched, {
            sessionID,
            messageID: SessionMessage.ID.create(),
            timestamp: DateTime.makeUnsafe(1),
            agent: AgentV2.ID.make("reviewer"),
          })
          .pipe(
            Effect.andThen(
              events.publish(SessionEvent.AgentSwitched, {
                sessionID,
                messageID: SessionMessage.ID.create(),
                timestamp: DateTime.makeUnsafe(2),
                agent: AgentV2.defaultID,
              }),
            ),
            Effect.asVoid,
          )
      })
      yield* session.prompt({ sessionID, prompt: new Prompt({ text: "Second" }), resume: false })

      requests.length = 0
      yield* session.resume(sessionID)

      expect(requests).toHaveLength(1)
      expect(
        yield* db
          .select({ replacementSeq: SessionContextEpochTable.replacement_seq })
          .from(SessionContextEpochTable)
          .where(eq(SessionContextEpochTable.session_id, sessionID))
          .get()
          .pipe(Effect.orDie),
      ).toEqual({ replacementSeq: null })
    }),
  )

  it.effect("rejects stale agent guidance when committing an existing-epoch replacement", () =>
    Effect.gen(function* () {
      yield* setup
      const session = yield* SessionV2.Service
      const events = yield* EventV2.Service
      const { db } = yield* Database.Service
      yield* session.prompt({ sessionID, prompt: new Prompt({ text: "First" }), resume: false })
      response = []
      yield* session.resume(sessionID)
      yield* events.publish(SessionEvent.AgentSwitched, {
        sessionID,
        messageID: SessionMessage.ID.create(),
        timestamp: DateTime.makeUnsafe(1),
        agent: AgentV2.ID.make("reviewer"),
      })
      const context = (text: string) =>
        Effect.succeed(
          SystemContext.make({
            key: systemContextKey,
            codec: Schema.toCodecJson(Schema.String),
            load: Effect.succeed(text),
            baseline: String,
            update: (_previous, current) => current,
          }),
        )
      const location = (yield* session.get(sessionID)).location

      expect(
        yield* SessionContextEpoch.prepare(
          db,
          events,
          context("Stale build context"),
          sessionID,
          location,
          AgentV2.defaultID,
        ).pipe(Effect.catchDefect(Effect.succeed)),
      ).toBeInstanceOf(SessionContextEpoch.AgentMismatch)

      expect(
        yield* SessionContextEpoch.prepare(
          db,
          events,
          context("Reviewer context"),
          sessionID,
          location,
          AgentV2.ID.make("reviewer"),
        ),
      ).toMatchObject({ baseline: "Reviewer context" })
    }),
  )

  it.effect("blocks a cross-agent provider turn while replacement context is unavailable", () =>
    Effect.gen(function* () {
      yield* setup
      const session = yield* SessionV2.Service
      const events = yield* EventV2.Service
      skillBaselines.set(AgentV2.defaultID, "Build skills")
      skillBaselines.set(AgentV2.ID.make("reviewer"), "Reviewer skills")
      yield* session.prompt({ sessionID, prompt: new Prompt({ text: "First" }), resume: false })
      response = []
      yield* session.resume(sessionID)
      yield* events.publish(SessionEvent.AgentSwitched, {
        sessionID,
        messageID: SessionMessage.ID.create(),
        timestamp: DateTime.makeUnsafe(1),
        agent: AgentV2.ID.make("reviewer"),
      })
      systemUnavailable = true
      yield* session.prompt({ sessionID, prompt: new Prompt({ text: "Second" }), resume: false })

      requests.length = 0
      const blocked = yield* session.resume(sessionID).pipe(Effect.exit)
      expect(Exit.isFailure(blocked)).toBe(true)
      if (Exit.isFailure(blocked))
        expect(Cause.squash(blocked.cause)).toBeInstanceOf(SessionContextEpoch.AgentReplacementBlocked)
      expect(requests).toHaveLength(0)

      systemUnavailable = false
      yield* session.resume(sessionID)
      expect(requests.map((request) => request.system.map((part) => part.text))).toEqual([
        ["Initial context\n\nReviewer skills"],
      ])
    }),
  )

  it.effect("admits removed context as a chronological System message", () =>
    Effect.gen(function* () {
      yield* setup
      const session = yield* SessionV2.Service
      yield* session.prompt({ sessionID, prompt: new Prompt({ text: "First" }), resume: false })

      requests.length = 0
      response = []
      yield* session.resume(sessionID)
      systemRemoved = true
      yield* session.prompt({ sessionID, prompt: new Prompt({ text: "Second" }), resume: false })
      yield* session.resume(sessionID)

      expect(requests[1]?.messages.map((message) => message.role)).toEqual(["user", "user", "system"])
      expect(requests[1]?.messages.at(-1)?.content).toEqual([
        { type: "text", text: "System context source removed: test/context" },
      ])
      expect(yield* session.messages({ sessionID })).toHaveLength(3)
    }),
  )

  it.effect("replaces the baseline lazily after a model switch and drops prior System updates", () =>
    Effect.gen(function* () {
      yield* setup
      const session = yield* SessionV2.Service
      const events = yield* EventV2.Service
      yield* session.prompt({ sessionID, prompt: new Prompt({ text: "First" }), resume: false })

      requests.length = 0
      response = []
      yield* session.resume(sessionID)
      systemBaseline = "Changed context"
      yield* session.prompt({ sessionID, prompt: new Prompt({ text: "Second" }), resume: false })
      yield* session.resume(sessionID)
      yield* events.publish(SessionEvent.ModelSwitched, {
        sessionID,
        messageID: SessionMessage.ID.create(),
        timestamp: DateTime.makeUnsafe(1),
        model: { id: ModelV2.ID.make("replacement"), providerID: ProviderV2.ID.make("fake") },
      })
      systemBaseline = "Replacement context"
      yield* session.prompt({ sessionID, prompt: new Prompt({ text: "Third" }), resume: false })
      yield* session.resume(sessionID)

      expect(requests.map((request) => request.system.map((part) => part.text))).toEqual([
        ["Initial context"],
        ["Initial context"],
        ["Replacement context"],
      ])
      expect(requests[1]?.messages.map((message) => message.role)).toEqual(["user", "user", "system"])
      expect(requests[2]?.messages.map((message) => message.role)).toEqual(["user", "user", "user"])
      expect((yield* session.context(sessionID)).map((message) => message.type)).toEqual([
        "user",
        "user",
        "model-switched",
        "user",
      ])
      yield* replaySessionProjection(sessionID)
      expect(yield* session.messages({ sessionID })).toHaveLength(5)
      yield* session.prompt({ sessionID, prompt: new Prompt({ text: "Fourth" }), resume: false })
      yield* session.resume(sessionID)
    }),
  )

  it.effect("defers replacement while admitted context is temporarily unavailable", () =>
    Effect.gen(function* () {
      yield* setup
      const session = yield* SessionV2.Service
      const events = yield* EventV2.Service
      yield* session.prompt({ sessionID, prompt: new Prompt({ text: "First" }), resume: false })

      requests.length = 0
      response = []
      yield* session.resume(sessionID)
      yield* events.publish(SessionEvent.ModelSwitched, {
        sessionID,
        messageID: SessionMessage.ID.create(),
        timestamp: DateTime.makeUnsafe(1),
        model: { id: ModelV2.ID.make("replacement"), providerID: ProviderV2.ID.make("fake") },
      })
      systemUnavailable = true
      yield* session.prompt({ sessionID, prompt: new Prompt({ text: "Second" }), resume: false })
      yield* session.resume(sessionID)
      systemUnavailable = false
      systemBaseline = "Replacement context"
      yield* session.prompt({ sessionID, prompt: new Prompt({ text: "Third" }), resume: false })
      yield* session.resume(sessionID)

      expect(requests.map((request) => request.system.map((part) => part.text))).toEqual([
        ["Initial context"],
        ["Initial context"],
        ["Replacement context"],
      ])
    }),
  )

  it.effect("advances a pending replacement to the latest invalidation boundary", () =>
    Effect.gen(function* () {
      yield* setup
      const session = yield* SessionV2.Service
      const events = yield* EventV2.Service
      const { db } = yield* Database.Service
      yield* session.prompt({ sessionID, prompt: new Prompt({ text: "First" }), resume: false })
      response = []
      yield* session.resume(sessionID)

      yield* events.publish(SessionEvent.ModelSwitched, {
        sessionID,
        messageID: SessionMessage.ID.create(),
        timestamp: DateTime.makeUnsafe(1),
        model: { id: ModelV2.ID.make("replacement-1"), providerID: ProviderV2.ID.make("fake") },
      })
      yield* events.publish(SessionEvent.ModelSwitched, {
        sessionID,
        messageID: SessionMessage.ID.create(),
        timestamp: DateTime.makeUnsafe(2),
        model: { id: ModelV2.ID.make("replacement-2"), providerID: ProviderV2.ID.make("fake") },
      })
      const latest = yield* SessionInput.latestSeq(db, sessionID)

      expect(
        yield* db
          .select({ replacementSeq: SessionContextEpochTable.replacement_seq })
          .from(SessionContextEpochTable)
          .where(eq(SessionContextEpochTable.session_id, sessionID))
          .get()
          .pipe(Effect.orDie),
      ).toEqual({ replacementSeq: latest })
    }),
  )

  it.effect("retries epoch preparation until observation-time invalidations settle", () =>
    Effect.gen(function* () {
      yield* setup
      const session = yield* SessionV2.Service
      const events = yield* EventV2.Service
      yield* session.prompt({ sessionID, prompt: new Prompt({ text: "First" }), resume: false })
      response = []
      yield* session.resume(sessionID)

      requests.length = 0
      systemBaseline = "Changed context"
      let invalidations = 0
      systemLoadHook = Effect.suspend(() => {
        if (invalidations === 4) return Effect.void
        invalidations++
        return events
          .publish(SessionEvent.ModelSwitched, {
            sessionID,
            messageID: SessionMessage.ID.create(),
            timestamp: DateTime.makeUnsafe(invalidations),
            model: { id: ModelV2.ID.make(`replacement-${invalidations}`), providerID: ProviderV2.ID.make("fake") },
          })
          .pipe(Effect.asVoid)
      })
      yield* session.prompt({ sessionID, prompt: new Prompt({ text: "Second" }), resume: false })

      yield* session.resume(sessionID)

      expect(invalidations).toBe(4)
      expect(requests).toHaveLength(1)
      expect(requests[0]?.system.map((part) => part.text)).toEqual(["Changed context"])
    }),
  )

  it.effect("replays retained context projections while replacement is pending", () =>
    Effect.gen(function* () {
      yield* setup
      const session = yield* SessionV2.Service
      const events = yield* EventV2.Service
      yield* session.prompt({ sessionID, prompt: new Prompt({ text: "First" }), resume: false })

      requests.length = 0
      response = []
      yield* session.resume(sessionID)
      systemBaseline = "Changed context"
      yield* session.prompt({ sessionID, prompt: new Prompt({ text: "Second" }), resume: false })
      yield* session.resume(sessionID)
      yield* events.publish(SessionEvent.ModelSwitched, {
        sessionID,
        messageID: SessionMessage.ID.create(),
        timestamp: DateTime.makeUnsafe(1),
        model: { id: ModelV2.ID.make("replacement"), providerID: ProviderV2.ID.make("fake") },
      })

      yield* replaySessionProjection(sessionID)
      systemBaseline = "Replacement context"
      yield* session.prompt({ sessionID, prompt: new Prompt({ text: "Third" }), resume: false })
      yield* session.resume(sessionID)
      expect(requests.at(-1)?.system.map((part) => part.text)).toEqual(["Replacement context"])
    }),
  )

  it.effect("replaces the baseline lazily after completed compaction without reopening replacement on replay", () =>
    Effect.gen(function* () {
      yield* setup
      const session = yield* SessionV2.Service
      const events = yield* EventV2.Service
      yield* session.prompt({ sessionID, prompt: new Prompt({ text: "First" }), resume: false })

      requests.length = 0
      response = []
      yield* session.resume(sessionID)
      yield* events.publish(SessionEvent.Compaction.Started, {
        sessionID,
        messageID: SessionMessage.ID.create(),
        timestamp: DateTime.makeUnsafe(1),
        reason: "manual",
      })
      yield* events.publish(SessionEvent.Compaction.Ended, {
        sessionID,
        timestamp: DateTime.makeUnsafe(2),
        text: "summary",
      })
      systemBaseline = "Replacement context"
      yield* session.prompt({ sessionID, prompt: new Prompt({ text: "Second" }), resume: false })
      yield* session.resume(sessionID)

      expect(requests.map((request) => request.system.map((part) => part.text))).toEqual([
        ["Initial context"],
        ["Replacement context"],
      ])
      yield* replaySessionProjection(sessionID)
      yield* session.prompt({ sessionID, prompt: new Prompt({ text: "Third" }), resume: false })
      yield* session.resume(sessionID)
    }),
  )

  it.effect("preserves effective System updates while compaction replacement is blocked", () =>
    Effect.gen(function* () {
      yield* setup
      const session = yield* SessionV2.Service
      const events = yield* EventV2.Service
      yield* session.prompt({ sessionID, prompt: new Prompt({ text: "First" }), resume: false })

      requests.length = 0
      response = []
      yield* session.resume(sessionID)
      systemBaseline = "Changed context"
      yield* session.prompt({ sessionID, prompt: new Prompt({ text: "Second" }), resume: false })
      yield* session.resume(sessionID)
      yield* events.publish(SessionEvent.Compaction.Started, {
        sessionID,
        messageID: SessionMessage.ID.create(),
        timestamp: DateTime.makeUnsafe(1),
        reason: "manual",
      })
      yield* events.publish(SessionEvent.Compaction.Ended, {
        sessionID,
        timestamp: DateTime.makeUnsafe(2),
        text: "summary",
      })
      systemUnavailable = true
      yield* session.prompt({ sessionID, prompt: new Prompt({ text: "Third" }), resume: false })
      yield* session.resume(sessionID)

      expect(requests.at(-1)?.system.map((part) => part.text)).toEqual(["Initial context"])
      expect(
        requests
          .at(-1)
          ?.messages.some(
            (message) =>
              message.role === "system" &&
              message.content[0]?.type === "text" &&
              message.content[0].text === "Changed context",
          ),
      ).toBe(true)
    }),
  )

  it.effect("projects reasoning and tool events without executing or continuing tools", () =>
    Effect.gen(function* () {
      yield* setup
      const session = yield* SessionV2.Service
      yield* session.prompt({ sessionID, prompt: new Prompt({ text: "Use tools" }), resume: false })

      requests.length = 0
      responses = undefined
      streamGate = undefined
      streamStarted = undefined
      response = [
        LLMEvent.stepStart({ index: 0 }),
        LLMEvent.reasoningStart({ id: "reasoning-1" }),
        LLMEvent.reasoningDelta({ id: "reasoning-1", text: "Think" }),
        LLMEvent.reasoningEnd({ id: "reasoning-1" }),
        LLMEvent.toolInputStart({ id: "call-error", name: "write" }),
        LLMEvent.toolInputDelta({ id: "call-error", name: "write", text: '{"path":"README.md"}' }),
        LLMEvent.toolInputEnd({ id: "call-error", name: "write" }),
        LLMEvent.toolCall({ id: "call-error", name: "write", input: { path: "README.md" }, providerExecuted: true }),
        LLMEvent.toolError({ id: "call-error", name: "write", message: "Denied" }),
        LLMEvent.toolResult({ id: "call-error", name: "write", result: { type: "error", value: "Denied" } }),
        LLMEvent.toolCall({
          id: "call-provider",
          name: "web_search",
          input: { query: "hello" },
          providerExecuted: true,
          providerMetadata: { fake: { source: "provider" } },
        }),
        LLMEvent.toolResult({
          id: "call-provider",
          name: "web_search",
          result: {
            type: "content",
            value: [
              { type: "text", text: "Hello" },
              { type: "media", mediaType: "image/png", data: "data:image/png;base64,aGVsbG8=", filename: "hello.png" },
            ],
          },
          providerExecuted: true,
          providerMetadata: { fake: { source: "provider" } },
        }),
        LLMEvent.stepFinish({
          index: 0,
          reason: "tool-calls",
          usage: {
            inputTokens: 10,
            nonCachedInputTokens: 8,
            outputTokens: 4,
            reasoningTokens: 1,
            cacheReadInputTokens: 2,
          },
        }),
        LLMEvent.finish({ reason: "tool-calls" }),
      ]

      yield* session.resume(sessionID)

      expect(requests).toHaveLength(1)
      expect(requests[0]?.tools.map((tool) => tool.name)).toEqual(["echo", "defect"])
      expect(yield* session.context(sessionID)).toMatchObject([
        { type: "user", text: "Use tools" },
        {
          type: "assistant",
          finish: "tool-calls",
          tokens: { input: 8, output: 3, reasoning: 1, cache: { read: 2, write: 0 } },
          content: [
            { type: "reasoning", id: "reasoning-1", text: "Think" },
            {
              type: "tool",
              id: "call-error",
              name: "write",
              state: {
                status: "error",
                input: { path: "README.md" },
                error: { type: "unknown", message: "Denied" },
              },
            },
            {
              type: "tool",
              id: "call-provider",
              name: "web_search",
              provider: { executed: true, metadata: { fake: { source: "provider" } } },
              state: {
                status: "completed",
                input: { query: "hello" },
                structured: {},
                content: [
                  { type: "text", text: "Hello" },
                  { type: "file", mime: "image/png", source: { type: "data", data: "aGVsbG8=" }, name: "hello.png" },
                ],
              },
            },
          ],
        },
      ])
    }),
  )

  it.effect("continues with reloaded history after durably settling one local tool call", () =>
    Effect.gen(function* () {
      yield* setup
      const session = yield* SessionV2.Service
      yield* session.prompt({ sessionID, prompt: new Prompt({ text: "Echo this" }), resume: false })

      requests.length = 0
      authorizations.length = 0
      executions.length = 0
      streamGate = undefined
      streamStarted = undefined
      responses = [
        [
          LLMEvent.stepStart({ index: 0 }),
          LLMEvent.toolCall({ id: "call-echo", name: "echo", input: { text: "hello" } }),
          LLMEvent.stepFinish({ index: 0, reason: "tool-calls" }),
          LLMEvent.finish({ reason: "tool-calls" }),
        ],
        [
          LLMEvent.stepStart({ index: 0 }),
          LLMEvent.textStart({ id: "text-final" }),
          LLMEvent.textDelta({ id: "text-final", text: "Done" }),
          LLMEvent.textEnd({ id: "text-final" }),
          LLMEvent.stepFinish({ index: 0, reason: "stop" }),
          LLMEvent.finish({ reason: "stop" }),
        ],
      ]

      yield* session.resume(sessionID)

      expect(requests).toHaveLength(2)
      expect(requests[1]?.messages.map((message) => message.role)).toEqual(["user", "assistant", "tool"])
      expect(authorizations).toMatchObject([{ sessionID, call: { id: "call-echo", name: "echo" } }])
      expect(executions).toEqual(["hello"])
      expect(yield* session.context(sessionID)).toMatchObject([
        { type: "user", text: "Echo this" },
        {
          type: "assistant",
          finish: "tool-calls",
          content: [
            {
              type: "tool",
              id: "call-echo",
              name: "echo",
              state: {
                status: "completed",
                input: { text: "hello" },
                structured: { text: "hello" },
                content: [{ type: "text", text: "hello" }],
              },
            },
          ],
        },
        { type: "assistant", finish: "stop", content: [{ type: "text", id: "text-final", text: "Done" }] },
      ])
    }),
  )

  it.effect("reloads a model switch before a tool-driven continuation turn", () =>
    Effect.gen(function* () {
      yield* setup
      const session = yield* SessionV2.Service
      const events = yield* EventV2.Service
      yield* session.prompt({ sessionID, prompt: new Prompt({ text: "Echo this" }), resume: false })

      requests.length = 0
      responses = [
        [
          LLMEvent.stepStart({ index: 0 }),
          LLMEvent.toolCall({ id: "call-echo", name: "echo", input: { text: "hello" } }),
          LLMEvent.stepFinish({ index: 0, reason: "tool-calls" }),
          LLMEvent.finish({ reason: "tool-calls" }),
        ],
        [
          LLMEvent.stepStart({ index: 0 }),
          LLMEvent.stepFinish({ index: 0, reason: "stop" }),
          LLMEvent.finish({ reason: "stop" }),
        ],
      ]
      toolExecutionGate = yield* Deferred.make<void>()
      toolExecutionsStarted = yield* Deferred.make<void>()
      toolExecutionsReady = 1
      const run = yield* Effect.forkChild(session.resume(sessionID))
      yield* Deferred.await(toolExecutionsStarted)
      yield* events.publish(SessionEvent.ModelSwitched, {
        sessionID,
        messageID: SessionMessage.ID.create(),
        timestamp: DateTime.makeUnsafe(1),
        model: { id: ModelV2.ID.make("replacement"), providerID: ProviderV2.ID.make("fake") },
      })
      systemBaseline = "Replacement context"
      yield* Deferred.succeed(toolExecutionGate, undefined)
      yield* Fiber.join(run)

      expect(requests.map((request) => request.model)).toEqual([model, replacementModel])
      expect(requests.map((request) => request.system.map((part) => part.text))).toEqual([
        ["Initial context"],
        ["Replacement context"],
      ])
    }),
  )

  it.effect("restores durable reasoning provider metadata in a second-turn request", () =>
    Effect.gen(function* () {
      yield* setup
      const session = yield* SessionV2.Service
      yield* session.prompt({ sessionID, prompt: new Prompt({ text: "Think first" }), resume: false })

      requests.length = 0
      response = [
        LLMEvent.stepStart({ index: 0 }),
        LLMEvent.reasoningStart({ id: "reasoning-anthropic" }),
        LLMEvent.reasoningDelta({ id: "reasoning-anthropic", text: "Signed thought" }),
        LLMEvent.reasoningEnd({ id: "reasoning-anthropic", providerMetadata: { anthropic: { signature: "sig_1" } } }),
        LLMEvent.reasoningStart({
          id: "reasoning-openai",
          providerMetadata: { openai: { itemId: "rs_1", reasoningEncryptedContent: null } },
        }),
        LLMEvent.reasoningDelta({ id: "reasoning-openai", text: "Encrypted thought" }),
        LLMEvent.reasoningEnd({
          id: "reasoning-openai",
          providerMetadata: { openai: { itemId: "rs_1", reasoningEncryptedContent: "encrypted-state" } },
        }),
        LLMEvent.stepFinish({ index: 0, reason: "stop" }),
        LLMEvent.finish({ reason: "stop" }),
      ]
      yield* session.resume(sessionID)
      yield* replaySessionProjection(sessionID)

      expect(yield* session.context(sessionID)).toMatchObject([
        { type: "user", text: "Think first" },
        {
          type: "assistant",
          content: [
            { type: "reasoning", text: "Signed thought", providerMetadata: { anthropic: { signature: "sig_1" } } },
            {
              type: "reasoning",
              text: "Encrypted thought",
              providerMetadata: { openai: { itemId: "rs_1", reasoningEncryptedContent: "encrypted-state" } },
            },
          ],
        },
      ])

      yield* session.prompt({ sessionID, prompt: new Prompt({ text: "Continue" }), resume: false })
      response = []
      yield* session.resume(sessionID)

      expect(requests[1]?.messages[1]?.content).toEqual([
        { type: "reasoning", text: "Signed thought", providerMetadata: { anthropic: { signature: "sig_1" } } },
        {
          type: "reasoning",
          text: "Encrypted thought",
          providerMetadata: { openai: { itemId: "rs_1", reasoningEncryptedContent: "encrypted-state" } },
        },
      ])
    }),
  )

  it.effect("replays durable provider-executed tool results inline in a second-turn request", () =>
    Effect.gen(function* () {
      yield* setup
      const session = yield* SessionV2.Service
      yield* session.prompt({ sessionID, prompt: new Prompt({ text: "Search first" }), resume: false })

      requests.length = 0
      response = [
        LLMEvent.stepStart({ index: 0 }),
        LLMEvent.toolCall({
          id: "hosted-search",
          name: "web_search",
          input: { query: "Effect" },
          providerExecuted: true,
          providerMetadata: { openai: { itemId: "hosted-search" } },
        }),
        LLMEvent.toolResult({
          id: "hosted-search",
          name: "web_search",
          result: { type: "json", value: [{ title: "Effect" }] },
          providerExecuted: true,
          providerMetadata: { anthropic: { blockType: "web_search_tool_result" } },
        }),
        LLMEvent.stepFinish({ index: 0, reason: "stop" }),
        LLMEvent.finish({ reason: "stop" }),
      ]
      yield* session.resume(sessionID)
      yield* replaySessionProjection(sessionID)

      yield* session.prompt({ sessionID, prompt: new Prompt({ text: "Continue" }), resume: false })
      response = []
      yield* session.resume(sessionID)

      expect(requests[1]?.messages.map((message) => message.role)).toEqual(["user", "assistant", "user"])
      expect(requests[1]?.messages[1]?.content).toMatchObject([
        {
          type: "tool-call",
          id: "hosted-search",
          name: "web_search",
          input: { query: "Effect" },
          providerExecuted: true,
          providerMetadata: { openai: { itemId: "hosted-search" } },
        },
        {
          type: "tool-result",
          id: "hosted-search",
          name: "web_search",
          result: { type: "json", value: [{ title: "Effect" }] },
          providerExecuted: true,
          providerMetadata: { anthropic: { blockType: "web_search_tool_result" } },
        },
      ])
    }),
  )

  it.effect("starts recorded local tools eagerly and awaits settlement before continuing", () =>
    Effect.gen(function* () {
      yield* setup
      const session = yield* SessionV2.Service
      yield* session.prompt({ sessionID, prompt: new Prompt({ text: "Echo five times" }), resume: false })

      requests.length = 0
      executions.length = 0
      toolExecutionGate = yield* Deferred.make<void>()
      toolExecutionsStarted = yield* Deferred.make<void>()
      const providerGate = yield* Deferred.make<void>()
      response = []
      responses = undefined
      const initial = Stream.fromIterable([
        LLMEvent.stepStart({ index: 0 }),
        ...Array.from({ length: 5 }, (_, index) =>
          LLMEvent.toolCall({ id: `call-echo-${index}`, name: "echo", input: { text: `${index}` } }),
        ),
      ])
      const final = Stream.fromIterable([
        LLMEvent.stepFinish({ index: 0, reason: "tool-calls" }),
        LLMEvent.finish({ reason: "tool-calls" }),
      ])
      streamGate = undefined
      responseStream = Stream.concat(
        initial,
        Stream.fromEffect(Deferred.await(providerGate)).pipe(Stream.flatMap(() => final)),
      )

      const run = yield* session.resume(sessionID).pipe(Effect.forkChild)
      yield* Deferred.await(toolExecutionsStarted)

      expect(executions).toHaveLength(5)
      expect(maxActiveToolExecutions).toBe(5)
      expect(yield* session.context(sessionID)).toMatchObject([
        { type: "user", text: "Echo five times" },
        {
          type: "assistant",
          content: Array.from({ length: 5 }, (_, index) => ({
            type: "tool",
            id: `call-echo-${index}`,
            state: { status: "running", input: { text: `${index}` } },
          })),
        },
      ])

      yield* Deferred.succeed(providerGate, undefined)
      yield* Effect.yieldNow
      expect(requests).toHaveLength(1)

      yield* Deferred.succeed(toolExecutionGate, undefined)
      yield* Fiber.join(run)
      toolExecutionGate = undefined
      toolExecutionsStarted = undefined

      expect(executions).toHaveLength(5)
      expect(maxActiveToolExecutions).toBe(5)
      expect(requests).toHaveLength(2)
    }),
  )

  it.effect("settles repeated provider-local tool call IDs against their owning assistant messages", () =>
    Effect.gen(function* () {
      yield* setup
      const session = yield* SessionV2.Service
      yield* session.prompt({ sessionID, prompt: new Prompt({ text: "Echo twice" }), resume: false })

      requests.length = 0
      executions.length = 0
      responses = [
        [
          LLMEvent.stepStart({ index: 0 }),
          LLMEvent.toolCall({ id: "tool_0", name: "echo", input: { text: "first" } }),
          LLMEvent.stepFinish({ index: 0, reason: "tool-calls" }),
          LLMEvent.finish({ reason: "tool-calls" }),
        ],
        [
          LLMEvent.stepStart({ index: 0 }),
          LLMEvent.toolCall({ id: "tool_0", name: "echo", input: { text: "second" } }),
          LLMEvent.stepFinish({ index: 0, reason: "tool-calls" }),
          LLMEvent.finish({ reason: "tool-calls" }),
        ],
        [],
      ]

      yield* session.resume(sessionID)

      expect(executions).toEqual(["first", "second"])
      expect(requests).toHaveLength(3)
      expect(yield* session.context(sessionID)).toMatchObject([
        { type: "user", text: "Echo twice" },
        {
          type: "assistant",
          content: [
            {
              type: "tool",
              id: "tool_0",
              state: { status: "completed", structured: { text: "first" }, content: [{ type: "text", text: "first" }] },
            },
          ],
        },
        {
          type: "assistant",
          content: [
            {
              type: "tool",
              id: "tool_0",
              state: {
                status: "completed",
                structured: { text: "second" },
                content: [{ type: "text", text: "second" }],
              },
            },
          ],
        },
      ])

      yield* replaySessionProjection(sessionID)

      expect(yield* session.context(sessionID)).toMatchObject([
        { type: "user", text: "Echo twice" },
        {
          type: "assistant",
          content: [
            {
              type: "tool",
              id: "tool_0",
              state: { status: "completed", structured: { text: "first" }, content: [{ type: "text", text: "first" }] },
            },
          ],
        },
        {
          type: "assistant",
          content: [
            {
              type: "tool",
              id: "tool_0",
              state: {
                status: "completed",
                structured: { text: "second" },
                content: [{ type: "text", text: "second" }],
              },
            },
          ],
        },
      ])
    }),
  )

  it.effect("joins concurrent resume calls into one active provider run", () =>
    Effect.gen(function* () {
      yield* setup
      const session = yield* SessionV2.Service
      yield* session.prompt({ sessionID, prompt: new Prompt({ text: "Run once" }), resume: false })

      requests.length = 0
      responses = undefined
      response = [
        LLMEvent.stepStart({ index: 0 }),
        LLMEvent.textStart({ id: "text-once" }),
        LLMEvent.textDelta({ id: "text-once", text: "Once" }),
        LLMEvent.textEnd({ id: "text-once" }),
        LLMEvent.stepFinish({ index: 0, reason: "stop" }),
        LLMEvent.finish({ reason: "stop" }),
      ]
      streamGate = yield* Deferred.make<void>()
      streamStarted = yield* Deferred.make<void>()

      const first = yield* session.resume(sessionID).pipe(Effect.forkChild)
      yield* Deferred.await(streamStarted)
      const second = yield* session.resume(sessionID).pipe(Effect.forkChild)
      yield* Effect.yieldNow

      expect(requests).toHaveLength(1)
      yield* Deferred.succeed(streamGate, undefined)
      yield* Fiber.join(first)
      yield* Fiber.join(second)
      streamGate = undefined
      streamStarted = undefined

      expect(requests).toHaveLength(1)
      expect(yield* session.context(sessionID)).toMatchObject([
        { type: "user", text: "Run once" },
        { type: "assistant", finish: "stop", content: [{ type: "text", id: "text-once", text: "Once" }] },
      ])
    }),
  )

  it.effect("steers an active provider turn with newly recorded prompts", () =>
    Effect.gen(function* () {
      yield* setup
      const session = yield* SessionV2.Service
      yield* session.prompt({ sessionID, prompt: new Prompt({ text: "Start working" }), resume: false })

      requests.length = 0
      responses = [
        [
          LLMEvent.stepStart({ index: 0 }),
          LLMEvent.stepFinish({ index: 0, reason: "stop" }),
          LLMEvent.finish({ reason: "stop" }),
        ],
        [
          LLMEvent.stepStart({ index: 0 }),
          LLMEvent.stepFinish({ index: 0, reason: "stop" }),
          LLMEvent.finish({ reason: "stop" }),
        ],
      ]
      streamGate = yield* Deferred.make<void>()
      streamStarted = yield* Deferred.make<void>()

      const first = yield* session.resume(sessionID).pipe(Effect.forkChild)
      yield* Deferred.await(streamStarted)
      yield* session.prompt({ sessionID, prompt: new Prompt({ text: "Change direction" }) })
      yield* Deferred.succeed(streamGate, undefined)
      yield* Fiber.join(first)
      streamGate = undefined
      streamStarted = undefined
      yield* Effect.yieldNow

      expect(requests).toHaveLength(2)
      expect(userTexts(requests[0]!)).toEqual(["Start working"])
      expect(userTexts(requests[1]!)).toEqual(["Start working", "Change direction"])
      expect((yield* session.context(sessionID)).map((message) => message.type)).toEqual([
        "user",
        "assistant",
        "user",
        "assistant",
      ])
    }),
  )

  it.effect("starts queued input after the active activity settles", () =>
    Effect.gen(function* () {
      yield* setup
      const session = yield* SessionV2.Service
      yield* session.prompt({ sessionID, prompt: new Prompt({ text: "Start working" }), resume: false })

      requests.length = 0
      responses = [
        [
          LLMEvent.stepStart({ index: 0 }),
          LLMEvent.toolCall({ id: "call-echo", name: "echo", input: { text: "hello" } }),
          LLMEvent.stepFinish({ index: 0, reason: "tool-calls" }),
          LLMEvent.finish({ reason: "tool-calls" }),
        ],
        [
          LLMEvent.stepStart({ index: 0 }),
          LLMEvent.stepFinish({ index: 0, reason: "stop" }),
          LLMEvent.finish({ reason: "stop" }),
        ],
        [
          LLMEvent.stepStart({ index: 0 }),
          LLMEvent.stepFinish({ index: 0, reason: "stop" }),
          LLMEvent.finish({ reason: "stop" }),
        ],
      ]
      streamGate = yield* Deferred.make<void>()
      streamStarted = yield* Deferred.make<void>()

      const first = yield* session.resume(sessionID).pipe(Effect.forkChild)
      yield* Deferred.await(streamStarted)
      yield* session.prompt({
        sessionID,
        prompt: new Prompt({ text: "Wait until the next activity" }),
        delivery: "queue",
      })
      yield* Deferred.succeed(streamGate, undefined)
      yield* Fiber.join(first)
      streamGate = undefined
      streamStarted = undefined

      expect(requests).toHaveLength(3)
      expect(userTexts(requests[0]!)).toEqual(["Start working"])
      expect(userTexts(requests[1]!)).toEqual(["Start working"])
      expect(userTexts(requests[2]!)).toEqual(["Start working", "Wait until the next activity"])
    }),
  )

  it.effect("preserves durable queued input for a later wake after interruption", () =>
    Effect.gen(function* () {
      yield* setup
      const session = yield* SessionV2.Service
      const { db } = yield* Database.Service
      yield* session.prompt({ sessionID, prompt: new Prompt({ text: "Interrupt current work" }), resume: false })

      requests.length = 0
      responses = [
        [],
        [
          LLMEvent.stepStart({ index: 0 }),
          LLMEvent.stepFinish({ index: 0, reason: "stop" }),
          LLMEvent.finish({ reason: "stop" }),
        ],
      ]
      streamGate = yield* Deferred.make<void>()
      streamStarted = yield* Deferred.make<void>()

      const run = yield* session.resume(sessionID).pipe(Effect.forkChild)
      yield* Deferred.await(streamStarted)
      yield* session.prompt({
        sessionID,
        prompt: new Prompt({ text: "Run after interrupt" }),
        delivery: "queue",
      })
      yield* session.interrupt(sessionID)
      expect(yield* Fiber.await(run)).toMatchObject({ _tag: "Failure" })
      expect(requests).toHaveLength(1)
      expect(yield* SessionInput.hasPending(db, sessionID, "queue")).toBe(true)
      const resumed = yield* session.resume(sessionID).pipe(Effect.forkChild)
      while (requests.length < 2) yield* Effect.yieldNow
      yield* Deferred.succeed(streamGate, undefined)
      yield* Fiber.join(resumed)
      streamGate = undefined
      streamStarted = undefined

      expect(requests).toHaveLength(2)
      expect(userTexts(requests[0]!)).toEqual(["Interrupt current work"])
      expect(userTexts(requests[1]!)).toEqual(["Interrupt current work", "Run after interrupt"])
    }),
  )

  it.effect("preserves durable steering input for a later resume after interruption", () =>
    Effect.gen(function* () {
      yield* setup
      const session = yield* SessionV2.Service
      const { db } = yield* Database.Service
      yield* session.prompt({ sessionID, prompt: new Prompt({ text: "Interrupt current work" }), resume: false })

      requests.length = 0
      responses = [
        [],
        [
          LLMEvent.stepStart({ index: 0 }),
          LLMEvent.stepFinish({ index: 0, reason: "stop" }),
          LLMEvent.finish({ reason: "stop" }),
        ],
      ]
      streamGate = yield* Deferred.make<void>()
      streamStarted = yield* Deferred.make<void>()

      const run = yield* session.resume(sessionID).pipe(Effect.forkChild)
      yield* Deferred.await(streamStarted)
      yield* session.prompt({
        sessionID,
        prompt: new Prompt({ text: "Steer after interrupt" }),
      })
      yield* session.interrupt(sessionID)
      expect(yield* Fiber.await(run)).toMatchObject({ _tag: "Failure" })
      expect(requests).toHaveLength(1)
      expect(yield* SessionInput.hasPending(db, sessionID, "steer")).toBe(true)

      const resumed = yield* session.resume(sessionID).pipe(Effect.forkChild)
      while (requests.length < 2) yield* Effect.yieldNow
      yield* Deferred.succeed(streamGate, undefined)
      yield* Fiber.join(resumed)
      streamGate = undefined
      streamStarted = undefined

      expect(requests).toHaveLength(2)
      expect(userTexts(requests[0]!)).toEqual(["Interrupt current work"])
      expect(userTexts(requests[1]!)).toEqual(["Interrupt current work", "Steer after interrupt"])
    }),
  )

  it.effect("runs queued active inputs as separate FIFO activities", () =>
    Effect.gen(function* () {
      yield* setup
      const session = yield* SessionV2.Service
      yield* session.prompt({ sessionID, prompt: new Prompt({ text: "Start working" }), resume: false })

      requests.length = 0
      responses = [
        [
          LLMEvent.stepStart({ index: 0 }),
          LLMEvent.stepFinish({ index: 0, reason: "stop" }),
          LLMEvent.finish({ reason: "stop" }),
        ],
        [
          LLMEvent.stepStart({ index: 0 }),
          LLMEvent.stepFinish({ index: 0, reason: "stop" }),
          LLMEvent.finish({ reason: "stop" }),
        ],
        [
          LLMEvent.stepStart({ index: 0 }),
          LLMEvent.stepFinish({ index: 0, reason: "stop" }),
          LLMEvent.finish({ reason: "stop" }),
        ],
      ]
      streamGate = yield* Deferred.make<void>()
      streamStarted = yield* Deferred.make<void>()

      const first = yield* session.resume(sessionID).pipe(Effect.forkChild)
      yield* Deferred.await(streamStarted)
      yield* session.prompt({ sessionID, prompt: new Prompt({ text: "Queue first" }), delivery: "queue" })
      yield* session.prompt({ sessionID, prompt: new Prompt({ text: "Queue second" }), delivery: "queue" })
      yield* Deferred.succeed(streamGate, undefined)
      yield* Fiber.join(first)
      streamGate = undefined
      streamStarted = undefined

      expect(requests).toHaveLength(3)
      expect(userTexts(requests[0]!)).toEqual(["Start working"])
      expect(userTexts(requests[1]!)).toEqual(["Start working", "Queue first"])
      expect(userTexts(requests[2]!)).toEqual(["Start working", "Queue first", "Queue second"])
    }),
  )

  it.effect("opens queued input after idle steering activity settles", () =>
    Effect.gen(function* () {
      yield* setup
      const session = yield* SessionV2.Service
      yield* session.prompt({ sessionID, prompt: new Prompt({ text: "Start steering activity" }), resume: false })
      yield* session.prompt({
        sessionID,
        prompt: new Prompt({ text: "Queue later activity" }),
        delivery: "queue",
        resume: false,
      })

      requests.length = 0
      responses = [
        [
          LLMEvent.stepStart({ index: 0 }),
          LLMEvent.stepFinish({ index: 0, reason: "stop" }),
          LLMEvent.finish({ reason: "stop" }),
        ],
        [
          LLMEvent.stepStart({ index: 0 }),
          LLMEvent.stepFinish({ index: 0, reason: "stop" }),
          LLMEvent.finish({ reason: "stop" }),
        ],
      ]

      yield* session.resume(sessionID)

      expect(requests).toHaveLength(2)
      expect(userTexts(requests[0]!)).toEqual(["Start steering activity"])
      expect(userTexts(requests[1]!)).toEqual(["Start steering activity", "Queue later activity"])
    }),
  )

  it.effect("coalesces steers into the active queued activity before starting the next queued activity", () =>
    Effect.gen(function* () {
      yield* setup
      const session = yield* SessionV2.Service
      yield* session.prompt({ sessionID, prompt: new Prompt({ text: "Start working" }), resume: false })

      requests.length = 0
      responses = [
        [
          LLMEvent.stepStart({ index: 0 }),
          LLMEvent.stepFinish({ index: 0, reason: "stop" }),
          LLMEvent.finish({ reason: "stop" }),
        ],
        [
          LLMEvent.stepStart({ index: 0 }),
          LLMEvent.stepFinish({ index: 0, reason: "stop" }),
          LLMEvent.finish({ reason: "stop" }),
        ],
        [
          LLMEvent.stepStart({ index: 0 }),
          LLMEvent.stepFinish({ index: 0, reason: "stop" }),
          LLMEvent.finish({ reason: "stop" }),
        ],
        [
          LLMEvent.stepStart({ index: 0 }),
          LLMEvent.stepFinish({ index: 0, reason: "stop" }),
          LLMEvent.finish({ reason: "stop" }),
        ],
      ]
      const firstGate = yield* Deferred.make<void>()
      const secondGate = yield* Deferred.make<void>()
      streamGate = firstGate

      const first = yield* session.resume(sessionID).pipe(Effect.forkChild)
      while (requests.length < 1) yield* Effect.yieldNow
      yield* session.prompt({ sessionID, prompt: new Prompt({ text: "Queue first" }), delivery: "queue" })
      yield* session.prompt({ sessionID, prompt: new Prompt({ text: "Queue second" }), delivery: "queue" })
      streamGate = secondGate
      yield* Deferred.succeed(firstGate, undefined)
      while (requests.length < 2) yield* Effect.yieldNow
      yield* session.prompt({ sessionID, prompt: new Prompt({ text: "Steer first queued activity" }) })
      yield* session.prompt({ sessionID, prompt: new Prompt({ text: "Also steer first queued activity" }) })
      yield* Deferred.succeed(secondGate, undefined)
      yield* Fiber.join(first)
      streamGate = undefined

      expect(requests).toHaveLength(4)
      expect(userTexts(requests[0]!)).toEqual(["Start working"])
      expect(userTexts(requests[1]!)).toEqual(["Start working", "Queue first"])
      expect(userTexts(requests[2]!)).toEqual([
        "Start working",
        "Queue first",
        "Steer first queued activity",
        "Also steer first queued activity",
      ])
      expect(userTexts(requests[3]!)).toEqual([
        "Start working",
        "Queue first",
        "Steer first queued activity",
        "Also steer first queued activity",
        "Queue second",
      ])
    }),
  )

  it.effect("coalesces multiple active steering prompts into one continuation turn", () =>
    Effect.gen(function* () {
      yield* setup
      const session = yield* SessionV2.Service
      yield* session.prompt({ sessionID, prompt: new Prompt({ text: "Start working" }), resume: false })

      requests.length = 0
      responses = [
        [
          LLMEvent.stepStart({ index: 0 }),
          LLMEvent.stepFinish({ index: 0, reason: "stop" }),
          LLMEvent.finish({ reason: "stop" }),
        ],
        [
          LLMEvent.stepStart({ index: 0 }),
          LLMEvent.stepFinish({ index: 0, reason: "stop" }),
          LLMEvent.finish({ reason: "stop" }),
        ],
      ]
      streamGate = yield* Deferred.make<void>()
      streamStarted = yield* Deferred.make<void>()

      const first = yield* session.resume(sessionID).pipe(Effect.forkChild)
      yield* Deferred.await(streamStarted)
      yield* session.prompt({ sessionID, prompt: new Prompt({ text: "First steer" }) })
      yield* session.prompt({ sessionID, prompt: new Prompt({ text: "Second steer" }) })
      yield* Deferred.succeed(streamGate, undefined)
      yield* Fiber.join(first)
      streamGate = undefined
      streamStarted = undefined
      yield* Effect.yieldNow

      expect(requests).toHaveLength(2)
      expect(userTexts(requests[1]!)).toEqual(["Start working", "First steer", "Second steer"])
      yield* (yield* SessionRunCoordinator.Service).wake(sessionID)
      yield* Effect.yieldNow
      expect(requests).toHaveLength(2)
    }),
  )

  it.effect("runs steering input accepted while the active provider turn fails", () =>
    Effect.gen(function* () {
      yield* setup
      const session = yield* SessionV2.Service
      yield* session.prompt({ sessionID, prompt: new Prompt({ text: "Start working" }), resume: false })

      requests.length = 0
      responses = undefined
      response = []
      streamFailure = providerUnavailable()
      streamGate = yield* Deferred.make<void>()
      streamStarted = yield* Deferred.make<void>()

      const first = yield* session.resume(sessionID).pipe(Effect.forkChild)
      yield* Deferred.await(streamStarted)
      yield* session.prompt({ sessionID, prompt: new Prompt({ text: "Recover with this" }) })
      yield* Deferred.succeed(streamGate, undefined)
      expect(yield* Fiber.join(first).pipe(Effect.flip)).toBe(streamFailure)

      streamFailure = undefined
      streamGate = undefined
      streamStarted = undefined
      yield* Effect.yieldNow

      expect(requests).toHaveLength(2)
      expect(userTexts(requests[1]!)).toEqual(["Start working", "Recover with this"])
    }),
  )

  it.effect("durably fails local tools left running by a prior process before continuing", () =>
    Effect.gen(function* () {
      yield* setup
      const session = yield* SessionV2.Service
      const events = yield* EventV2.Service
      yield* session.prompt({ sessionID, prompt: new Prompt({ text: "Recover interrupted tool" }), resume: false })
      yield* SessionInput.promoteSteers((yield* Database.Service).db, events, sessionID, Number.MAX_SAFE_INTEGER)
      const assistantMessageID = SessionMessage.ID.create()
      yield* events.publish(SessionEvent.Step.Started, {
        sessionID,
        assistantMessageID,
        timestamp: yield* DateTime.now,
        agent: "build",
        model: { id: ModelV2.ID.make("fake-model"), providerID: ProviderV2.ID.make("fake") },
      })
      yield* events.publish(SessionEvent.Tool.Input.Started, {
        sessionID,
        timestamp: yield* DateTime.now,
        assistantMessageID,
        callID: "call-interrupted",
        name: "echo",
      })
      yield* events.publish(SessionEvent.Tool.Input.Ended, {
        sessionID,
        timestamp: yield* DateTime.now,
        assistantMessageID,
        callID: "call-interrupted",
        text: '{"text":"stale"}',
      })
      yield* events.publish(SessionEvent.Tool.Called, {
        sessionID,
        timestamp: yield* DateTime.now,
        assistantMessageID,
        callID: "call-interrupted",
        tool: "echo",
        input: { text: "stale" },
        provider: { executed: false },
      })
      requests.length = 0
      response = []
      yield* session.resume(sessionID)

      expect(requests).toHaveLength(1)
      expect(requests[0]?.messages.map((message) => message.role)).toEqual(["user", "assistant", "tool"])
      expect(yield* session.context(sessionID)).toMatchObject([
        { type: "user", text: "Recover interrupted tool" },
        {
          type: "assistant",
          content: [
            {
              type: "tool",
              id: "call-interrupted",
              state: { status: "error", error: { type: "unknown", message: "Tool execution interrupted" } },
            },
          ],
        },
      ])
    }),
  )

  it.effect("durably fails hosted tools left running by a prior process before continuing inline", () =>
    Effect.gen(function* () {
      yield* setup
      const session = yield* SessionV2.Service
      const events = yield* EventV2.Service
      yield* session.prompt({
        sessionID,
        prompt: new Prompt({ text: "Recover interrupted hosted tool" }),
        resume: false,
      })
      yield* SessionInput.promoteSteers((yield* Database.Service).db, events, sessionID, Number.MAX_SAFE_INTEGER)
      const assistantMessageID = SessionMessage.ID.create()
      yield* events.publish(SessionEvent.Step.Started, {
        sessionID,
        assistantMessageID,
        timestamp: yield* DateTime.now,
        agent: "build",
        model: { id: ModelV2.ID.make("fake-model"), providerID: ProviderV2.ID.make("fake") },
      })
      yield* events.publish(SessionEvent.Tool.Input.Started, {
        sessionID,
        timestamp: yield* DateTime.now,
        assistantMessageID,
        callID: "call-hosted-interrupted",
        name: "web_search",
      })
      yield* events.publish(SessionEvent.Tool.Input.Ended, {
        sessionID,
        timestamp: yield* DateTime.now,
        assistantMessageID,
        callID: "call-hosted-interrupted",
        text: '{"query":"stale"}',
      })
      yield* events.publish(SessionEvent.Tool.Called, {
        sessionID,
        timestamp: yield* DateTime.now,
        assistantMessageID,
        callID: "call-hosted-interrupted",
        tool: "web_search",
        input: { query: "stale" },
        provider: { executed: true, metadata: { openai: { itemId: "call-hosted-interrupted" } } },
      })
      requests.length = 0
      response = []
      yield* session.resume(sessionID)

      expect(requests).toHaveLength(1)
      expect(requests[0]?.messages.map((message) => message.role)).toEqual(["user", "assistant"])
      expect(requests[0]?.messages[1]?.content).toMatchObject([
        {
          type: "tool-call",
          id: "call-hosted-interrupted",
          providerExecuted: true,
          providerMetadata: { openai: { itemId: "call-hosted-interrupted" } },
        },
        { type: "tool-result", id: "call-hosted-interrupted", providerExecuted: true, result: { type: "error" } },
      ])
    }),
  )

  it.effect("durably fails pending tool input left by a prior process before continuing", () =>
    Effect.gen(function* () {
      yield* setup
      const session = yield* SessionV2.Service
      const events = yield* EventV2.Service
      yield* session.prompt({
        sessionID,
        prompt: new Prompt({ text: "Recover interrupted tool input" }),
        resume: false,
      })
      yield* SessionInput.promoteSteers((yield* Database.Service).db, events, sessionID, Number.MAX_SAFE_INTEGER)
      const assistantMessageID = SessionMessage.ID.create()
      yield* events.publish(SessionEvent.Step.Started, {
        sessionID,
        assistantMessageID,
        timestamp: yield* DateTime.now,
        agent: "build",
        model: { id: ModelV2.ID.make("fake-model"), providerID: ProviderV2.ID.make("fake") },
      })
      yield* events.publish(SessionEvent.Tool.Input.Started, {
        sessionID,
        timestamp: yield* DateTime.now,
        assistantMessageID,
        callID: "call-pending-interrupted",
        name: "echo",
      })
      requests.length = 0
      response = []
      yield* session.resume(sessionID)

      expect(requests).toHaveLength(1)
      expect(requests[0]?.messages.map((message) => message.role)).toEqual(["user", "assistant", "tool"])
      expect(yield* session.context(sessionID)).toMatchObject([
        { type: "user", text: "Recover interrupted tool input" },
        { type: "assistant", content: [{ type: "tool", id: "call-pending-interrupted", state: { status: "error" } }] },
      ])
    }),
  )

  it.effect("starts the first queued activity when woken while idle", () =>
    Effect.gen(function* () {
      yield* setup
      const session = yield* SessionV2.Service
      yield* session.prompt({
        sessionID,
        prompt: new Prompt({ text: "Wait for fresh activity" }),
        delivery: "queue",
        resume: false,
      })

      requests.length = 0
      yield* (yield* SessionRunCoordinator.Service).wake(sessionID)
      yield* Effect.yieldNow

      expect(requests).toHaveLength(1)
      expect(userTexts(requests[0]!)).toEqual(["Wait for fresh activity"])
    }),
  )

  it.effect("does not spend one activity step budget across queued activities", () =>
    Effect.gen(function* () {
      yield* setup
      const session = yield* SessionV2.Service
      const queued = Array.from({ length: 26 }, (_, index) => `Queued activity ${index + 1}`)
      for (const text of queued) {
        yield* session.prompt({ sessionID, prompt: new Prompt({ text }), delivery: "queue", resume: false })
      }

      requests.length = 0
      responses = queued.map(() => [
        LLMEvent.stepStart({ index: 0 }),
        LLMEvent.stepFinish({ index: 0, reason: "stop" }),
        LLMEvent.finish({ reason: "stop" }),
      ])

      yield* session.resume(sessionID)

      expect(requests).toHaveLength(queued.length)
      expect(userTexts(requests.at(-1)!)).toEqual(queued)
    }),
  )

  it.effect("retries inbox input after prompt projection rolls back", () =>
    Effect.gen(function* () {
      yield* setup
      const session = yield* SessionV2.Service
      const events = yield* EventV2.Service
      const defect = new Error("fail after prompt promotion")
      let fail = true
      yield* events.project(SessionEvent.PromptLifecycle.Promoted, () => (fail ? Effect.die(defect) : Effect.void))
      yield* session.prompt({ sessionID, prompt: new Prompt({ text: "Recover promoted input" }), resume: false })

      expect(yield* session.resume(sessionID).pipe(Effect.catchDefect(Effect.succeed))).toBe(defect)
      fail = false
      requests.length = 0
      response = [
        LLMEvent.stepStart({ index: 0 }),
        LLMEvent.stepFinish({ index: 0, reason: "stop" }),
        LLMEvent.finish({ reason: "stop" }),
      ]

      yield* (yield* SessionRunCoordinator.Service).wake(sessionID)
      while (requests.length === 0) yield* Effect.yieldNow

      expect(userTexts(requests[0]!)).toEqual(["Recover promoted input"])
    }),
  )

  it.effect("does not strand a committed promotion when a post-commit listener defects", () =>
    Effect.gen(function* () {
      yield* setup
      const session = yield* SessionV2.Service
      const events = yield* EventV2.Service
      yield* events.listen((event) =>
        event.type === SessionEvent.PromptLifecycle.Promoted.type
          ? Effect.die("fail after prompt promotion commits")
          : Effect.void,
      )
      yield* session.prompt({
        sessionID,
        prompt: new Prompt({ text: "Run committed promotion" }),
        resume: false,
      })

      requests.length = 0
      yield* session.resume(sessionID)

      expect(requests).toHaveLength(1)
      expect(userTexts(requests[0]!)).toEqual(["Run committed promotion"])
    }),
  )

  it.effect("runs different sessions concurrently", () =>
    Effect.gen(function* () {
      yield* setup
      yield* insertSession(otherSessionID)
      const session = yield* SessionV2.Service
      yield* session.prompt({ sessionID, prompt: new Prompt({ text: "Run first" }), resume: false })
      yield* session.prompt({ sessionID: otherSessionID, prompt: new Prompt({ text: "Run second" }), resume: false })

      requests.length = 0
      responses = undefined
      response = []
      streamGate = yield* Deferred.make<void>()
      streamStarted = yield* Deferred.make<void>()

      const first = yield* session.resume(sessionID).pipe(Effect.forkChild)
      yield* Deferred.await(streamStarted)
      const second = yield* session.resume(otherSessionID).pipe(Effect.forkChild)
      yield* Effect.yieldNow

      expect(requests).toHaveLength(2)
      yield* Deferred.succeed(streamGate, undefined)
      yield* Fiber.join(first)
      yield* Fiber.join(second)
      streamGate = undefined
      streamStarted = undefined
    }),
  )

  it.effect("fans out one failed run and allows a later retry", () =>
    Effect.gen(function* () {
      yield* setup
      const session = yield* SessionV2.Service
      yield* session.prompt({ sessionID, prompt: new Prompt({ text: "Retry after failure" }), resume: false })

      requests.length = 0
      responses = undefined
      response = []
      streamFailure = providerUnavailable()
      streamGate = yield* Deferred.make<void>()
      streamStarted = yield* Deferred.make<void>()

      const first = yield* session.resume(sessionID).pipe(Effect.forkChild)
      yield* Deferred.await(streamStarted)
      const second = yield* session.resume(sessionID).pipe(Effect.forkChild)
      yield* Effect.yieldNow

      expect(requests).toHaveLength(1)
      yield* Deferred.succeed(streamGate, undefined)
      const [firstExit, secondExit] = yield* Effect.all([Fiber.await(first), Fiber.await(second)])
      expect(secondExit).toEqual(firstExit)

      streamFailure = undefined
      streamGate = undefined
      streamStarted = undefined
      yield* session.resume(sessionID)
      expect(requests).toHaveLength(2)
    }),
  )

  it.effect("durably settles local tool failures before continuing", () =>
    Effect.gen(function* () {
      yield* setup
      const session = yield* SessionV2.Service
      yield* session.prompt({ sessionID, prompt: new Prompt({ text: "Call missing" }), resume: false })

      requests.length = 0
      responses = [
        [
          LLMEvent.stepStart({ index: 0 }),
          LLMEvent.toolCall({ id: "call-missing", name: "missing", input: {} }),
          LLMEvent.stepFinish({ index: 0, reason: "tool-calls" }),
          LLMEvent.finish({ reason: "tool-calls" }),
        ],
        [
          LLMEvent.stepStart({ index: 0 }),
          LLMEvent.textStart({ id: "text-after-error" }),
          LLMEvent.textDelta({ id: "text-after-error", text: "Recovered" }),
          LLMEvent.textEnd({ id: "text-after-error" }),
          LLMEvent.stepFinish({ index: 0, reason: "stop" }),
          LLMEvent.finish({ reason: "stop" }),
        ],
      ]
      streamGate = undefined
      streamStarted = undefined

      yield* session.resume(sessionID)

      expect(requests).toHaveLength(2)
      expect(yield* session.context(sessionID)).toMatchObject([
        { type: "user", text: "Call missing" },
        {
          type: "assistant",
          content: [
            {
              type: "tool",
              id: "call-missing",
              state: { status: "error", error: { message: "Unknown tool: missing" } },
            },
          ],
        },
        { type: "assistant", finish: "stop", content: [{ type: "text", id: "text-after-error", text: "Recovered" }] },
      ])
    }),
  )

  it.effect("durably settles unexpected local tool defects before continuing", () =>
    Effect.gen(function* () {
      yield* setup
      const session = yield* SessionV2.Service
      yield* session.prompt({ sessionID, prompt: new Prompt({ text: "Call defect" }), resume: false })

      requests.length = 0
      responses = [
        [
          LLMEvent.stepStart({ index: 0 }),
          LLMEvent.toolCall({ id: "call-defect", name: "defect", input: {} }),
          LLMEvent.stepFinish({ index: 0, reason: "tool-calls" }),
          LLMEvent.finish({ reason: "tool-calls" }),
        ],
        [],
      ]

      yield* session.resume(sessionID)

      expect(requests).toHaveLength(2)
      expect(yield* session.context(sessionID)).toMatchObject([
        { type: "user", text: "Call defect" },
        {
          type: "assistant",
          content: [
            {
              type: "tool",
              id: "call-defect",
              state: { status: "error", error: { message: "unexpected tool defect" } },
            },
          ],
        },
      ])
    }),
  )

  it.effect("interrupts runner continuation when a question is dismissed", () =>
    Effect.gen(function* () {
      yield* setup
      const session = yield* SessionV2.Service
      const registry = yield* ToolRegistry.Service
      const questions = yield* QuestionV2.Service
      const transform = yield* registry.transform()
      yield* transform((editor) =>
        editor.set("question", {
          tool: Tool.make({
            description: "Ask the user",
            parameters: Schema.Struct({}),
            success: Schema.Struct({}),
          }),
          execute: ({ sessionID }) => questions.ask({ sessionID, questions: [] }).pipe(Effect.as({}), Effect.orDie),
        }),
      )
      yield* session.prompt({ sessionID, prompt: new Prompt({ text: "Ask then stop" }), resume: false })

      requests.length = 0
      responses = [
        [
          LLMEvent.stepStart({ index: 0 }),
          LLMEvent.toolCall({ id: "call-question", name: "question", input: {} }),
          LLMEvent.stepFinish({ index: 0, reason: "tool-calls" }),
          LLMEvent.finish({ reason: "tool-calls" }),
        ],
        [],
      ]

      const run = yield* session.resume(sessionID).pipe(Effect.exit, Effect.forkChild)
      let pending = yield* questions.list()
      while (pending.length === 0) {
        yield* Effect.yieldNow
        pending = yield* questions.list()
      }
      yield* questions.reject(pending[0]!.id)
      const exit = yield* Fiber.join(run)

      expect(exit._tag).toBe("Failure")
      if (exit._tag === "Failure") expect(Cause.hasInterruptsOnly(exit.cause)).toBe(true)
      expect(requests).toHaveLength(1)
      expect(yield* session.context(sessionID)).toMatchObject([
        { type: "user", text: "Ask then stop" },
        {
          type: "assistant",
          content: [
            {
              type: "tool",
              id: "call-question",
              state: { status: "error", error: { type: "unknown", message: "Tool execution interrupted" } },
            },
          ],
        },
      ])
    }),
  )

  it.effect("awaits started local tools before surfacing provider stream failure", () =>
    Effect.gen(function* () {
      yield* setup
      const session = yield* SessionV2.Service
      yield* session.prompt({ sessionID, prompt: new Prompt({ text: "Settle before failing" }), resume: false })
      const failure = providerUnavailable()
      toolExecutionGate = yield* Deferred.make<void>()
      responseStream = Stream.concat(
        Stream.fromIterable([
          LLMEvent.stepStart({ index: 0 }),
          LLMEvent.toolCall({ id: "call-before-failure", name: "echo", input: { text: "settle" } }),
        ]),
        Stream.fail(failure),
      )

      const run = yield* session.resume(sessionID).pipe(Effect.forkChild)
      while (executions.length === 0) yield* Effect.yieldNow
      yield* Effect.yieldNow
      yield* Deferred.succeed(toolExecutionGate, undefined)
      expect(yield* Fiber.join(run).pipe(Effect.flip)).toBe(failure)
      toolExecutionGate = undefined

      expect(yield* session.context(sessionID)).toMatchObject([
        { type: "user", text: "Settle before failing" },
        {
          type: "assistant",
          content: [
            { type: "tool", id: "call-before-failure", state: { status: "completed", structured: { text: "settle" } } },
          ],
        },
      ])
    }),
  )

  it.effect("durably fails blocked local tools when a provider turn is interrupted", () =>
    Effect.gen(function* () {
      yield* setup
      const session = yield* SessionV2.Service
      yield* session.prompt({ sessionID, prompt: new Prompt({ text: "Interrupt blocked tool" }), resume: false })
      executions.length = 0
      toolExecutionGate = yield* Deferred.make<void>()
      responseStream = Stream.concat(
        Stream.fromIterable([
          LLMEvent.stepStart({ index: 0 }),
          LLMEvent.toolCall({ id: "call-before-interrupt", name: "echo", input: { text: "blocked" } }),
        ]),
        Stream.never,
      )

      const run = yield* session.resume(sessionID).pipe(Effect.forkChild)
      while (executions.length === 0) yield* Effect.yieldNow
      yield* session.interrupt(sessionID)
      toolExecutionGate = undefined

      expect(yield* Fiber.await(run)).toMatchObject({ _tag: "Failure" })
      yield* session.interrupt(sessionID)
      expect(yield* session.context(sessionID)).toMatchObject([
        { type: "user", text: "Interrupt blocked tool" },
        {
          type: "assistant",
          content: [
            {
              type: "tool",
              id: "call-before-interrupt",
              state: { status: "error", error: { type: "unknown", message: "Tool execution interrupted" } },
            },
          ],
        },
      ])

      yield* replaySessionProjection(sessionID)

      expect(yield* session.context(sessionID)).toMatchObject([
        { type: "user", text: "Interrupt blocked tool" },
        { type: "assistant", content: [{ type: "tool", id: "call-before-interrupt", state: { status: "error" } }] },
      ])
      requests.length = 0
      responseStream = undefined
      response = []
      yield* session.resume(sessionID)
      expect(requests[0]?.messages.map((message) => message.role)).toEqual(["user", "assistant", "tool"])
    }),
  )

  it.effect("interrupts a blocked provider turn without local tool activity", () =>
    Effect.gen(function* () {
      yield* setup
      const session = yield* SessionV2.Service
      yield* session.prompt({ sessionID, prompt: new Prompt({ text: "Interrupt provider" }), resume: false })
      requests.length = 0
      response = []
      streamGate = yield* Deferred.make<void>()
      streamStarted = yield* Deferred.make<void>()

      const run = yield* session.resume(sessionID).pipe(Effect.forkChild)
      yield* Deferred.await(streamStarted)
      yield* session.interrupt(sessionID)
      const exit = yield* Fiber.await(run)
      streamGate = undefined
      streamStarted = undefined

      expect(Exit.isFailure(exit) && Cause.hasInterruptsOnly(exit.cause)).toBeTrue()
      expect(requests).toHaveLength(1)
      yield* session.interrupt(sessionID)
    }),
  )

  it.effect("durably fails blocked local tools when interrupted while awaiting settlement", () =>
    Effect.gen(function* () {
      yield* setup
      const session = yield* SessionV2.Service
      yield* session.prompt({ sessionID, prompt: new Prompt({ text: "Interrupt tool settlement" }), resume: false })
      executions.length = 0
      toolExecutionGate = yield* Deferred.make<void>()
      response = [
        LLMEvent.stepStart({ index: 0 }),
        LLMEvent.toolCall({ id: "call-await-interrupt", name: "echo", input: { text: "blocked" } }),
        LLMEvent.stepFinish({ index: 0, reason: "tool-calls" }),
        LLMEvent.finish({ reason: "tool-calls" }),
      ]

      const runner = yield* SessionRunner.Service
      const run = yield* runner.run({ sessionID, force: true }).pipe(Effect.forkChild)
      while (executions.length === 0) yield* Effect.yieldNow
      yield* Fiber.interrupt(run)
      toolExecutionGate = undefined

      expect(yield* Fiber.await(run)).toMatchObject({ _tag: "Failure" })
      expect(yield* session.context(sessionID)).toMatchObject([
        { type: "user", text: "Interrupt tool settlement" },
        {
          type: "assistant",
          content: [
            {
              type: "tool",
              id: "call-await-interrupt",
              state: { status: "error", error: { type: "unknown", message: "Tool execution interrupted" } },
            },
          ],
        },
      ])
    }),
  )

  it.effect("fails after the bounded number of local tool continuation steps", () =>
    Effect.gen(function* () {
      yield* setup
      const session = yield* SessionV2.Service
      yield* session.prompt({ sessionID, prompt: new Prompt({ text: "Loop forever" }), resume: false })

      requests.length = 0
      authorizations.length = 0
      executions.length = 0
      streamGate = undefined
      streamStarted = undefined
      responses = Array.from({ length: 25 }, (_, index) => [
        LLMEvent.stepStart({ index: 0 }),
        LLMEvent.toolCall({ id: `call-echo-${index}`, name: "echo", input: { text: `${index}` } }),
        LLMEvent.stepFinish({ index: 0, reason: "tool-calls" }),
        LLMEvent.finish({ reason: "tool-calls" }),
      ])

      const failure = yield* session.resume(sessionID).pipe(Effect.flip)

      expect(failure).toMatchObject({ _tag: "SessionRunner.StepLimitExceededError", sessionID, limit: 25 })
      expect(requests).toHaveLength(25)
      expect(executions).toHaveLength(25)
    }),
  )

  it.effect("does not restart a capped tool loop for a coalesced stale wake", () =>
    Effect.gen(function* () {
      yield* setup
      const session = yield* SessionV2.Service
      const coordinator = yield* SessionRunCoordinator.Service
      yield* session.prompt({ sessionID, prompt: new Prompt({ text: "Loop forever" }), resume: false })

      requests.length = 0
      responses = Array.from({ length: 25 }, (_, index) => [
        LLMEvent.stepStart({ index: 0 }),
        LLMEvent.toolCall({ id: `call-capped-${index}`, name: "echo", input: { text: `${index}` } }),
        LLMEvent.stepFinish({ index: 0, reason: "tool-calls" }),
        LLMEvent.finish({ reason: "tool-calls" }),
      ])
      streamGate = yield* Deferred.make<void>()
      streamStarted = yield* Deferred.make<void>()

      const run = yield* session.resume(sessionID).pipe(Effect.forkChild)
      yield* Deferred.await(streamStarted)
      yield* coordinator.wake(sessionID)
      yield* Deferred.succeed(streamGate, undefined)
      expect(yield* Fiber.join(run).pipe(Effect.flip)).toMatchObject({ _tag: "SessionRunner.StepLimitExceededError" })
      streamGate = undefined
      streamStarted = undefined
      yield* Effect.yieldNow

      expect(requests).toHaveLength(25)
    }),
  )

  it.effect("accepts a terminal response on the final bounded provider turn", () =>
    Effect.gen(function* () {
      yield* setup
      const session = yield* SessionV2.Service
      yield* session.prompt({ sessionID, prompt: new Prompt({ text: "Finish at the limit" }), resume: false })

      requests.length = 0
      responses = [
        ...Array.from({ length: 24 }, (_, index) => [
          LLMEvent.stepStart({ index: 0 }),
          LLMEvent.toolCall({ id: `call-terminal-${index}`, name: "echo", input: { text: `${index}` } }),
          LLMEvent.stepFinish({ index: 0, reason: "tool-calls" }),
          LLMEvent.finish({ reason: "tool-calls" }),
        ]),
        [
          LLMEvent.stepStart({ index: 0 }),
          LLMEvent.stepFinish({ index: 0, reason: "stop" }),
          LLMEvent.finish({ reason: "stop" }),
        ],
      ]

      yield* session.resume(sessionID)

      expect(requests).toHaveLength(25)
    }),
  )

  it.effect("projects provider errors as terminal assistant step failures", () =>
    Effect.gen(function* () {
      yield* setup
      const session = yield* SessionV2.Service
      yield* session.prompt({ sessionID, prompt: new Prompt({ text: "Fail durably" }), resume: false })

      requests.length = 0
      responses = undefined
      streamGate = undefined
      streamStarted = undefined
      response = [LLMEvent.stepStart({ index: 0 }), LLMEvent.providerError({ message: "Provider unavailable" })]

      yield* session.resume(sessionID)

      expect(requests).toHaveLength(1)
      expect(yield* session.context(sessionID)).toMatchObject([
        { type: "user", text: "Fail durably" },
        { type: "assistant", finish: "error", error: { type: "unknown", message: "Provider unavailable" } },
      ])
    }),
  )

  it.effect("projects provider errors emitted before assistant step start", () =>
    Effect.gen(function* () {
      yield* setup
      const session = yield* SessionV2.Service
      yield* session.prompt({ sessionID, prompt: new Prompt({ text: "Fail before step" }), resume: false })

      requests.length = 0
      response = [LLMEvent.providerError({ message: "Provider unavailable" })]

      yield* session.resume(sessionID)

      expect(requests).toHaveLength(1)
      expect(yield* session.context(sessionID)).toMatchObject([
        { type: "user", text: "Fail before step" },
        { type: "assistant", finish: "error", error: { type: "unknown", message: "Provider unavailable" } },
      ])
    }),
  )

  it.effect("projects raw provider stream failures as terminal assistant step failures", () =>
    Effect.gen(function* () {
      yield* setup
      const session = yield* SessionV2.Service
      yield* session.prompt({ sessionID, prompt: new Prompt({ text: "Fail raw stream durably" }), resume: false })
      const failure = providerUnavailable()
      responseStream = Stream.fail(failure)

      expect(yield* session.resume(sessionID).pipe(Effect.flip)).toBe(failure)
      yield* replaySessionProjection(sessionID)
      expect(yield* session.context(sessionID)).toMatchObject([
        { type: "user", text: "Fail raw stream durably" },
        { type: "assistant", finish: "error", error: { type: "unknown", message: "Provider unavailable" } },
      ])
    }),
  )

  it.effect("does not continue automatically after a provider error follows a local tool call", () =>
    Effect.gen(function* () {
      yield* setup
      const session = yield* SessionV2.Service
      yield* session.prompt({
        sessionID,
        prompt: new Prompt({ text: "Do not continue failed provider" }),
        resume: false,
      })

      requests.length = 0
      const executionCount = executions.length
      response = [
        LLMEvent.stepStart({ index: 0 }),
        LLMEvent.toolCall({ id: "call-before-provider-error", name: "echo", input: { text: "settled" } }),
        LLMEvent.providerError({ message: "Provider unavailable" }),
      ]

      yield* session.resume(sessionID)

      expect(requests).toHaveLength(1)
      expect(executions.slice(executionCount)).toEqual(["settled"])
    }),
  )

  it.effect("durably fails a hosted tool when its provider errors before returning a result", () =>
    Effect.gen(function* () {
      yield* setup
      const session = yield* SessionV2.Service
      yield* session.prompt({ sessionID, prompt: new Prompt({ text: "Fail hosted tool durably" }), resume: false })

      requests.length = 0
      response = [
        LLMEvent.stepStart({ index: 0 }),
        LLMEvent.toolCall({
          id: "call-hosted-provider-error",
          name: "web_search",
          input: { query: "effect" },
          providerExecuted: true,
        }),
        LLMEvent.providerError({ message: "Provider unavailable" }),
      ]

      yield* session.resume(sessionID)

      expect(requests).toHaveLength(1)
      expect(yield* session.context(sessionID)).toMatchObject([
        { type: "user", text: "Fail hosted tool durably" },
        {
          type: "assistant",
          content: [{ type: "tool", id: "call-hosted-provider-error", state: { status: "error" } }],
        },
      ])
    }),
  )

  it.effect("durably fails a hosted tool left unresolved at normal provider EOF", () =>
    Effect.gen(function* () {
      yield* setup
      const session = yield* SessionV2.Service
      yield* session.prompt({ sessionID, prompt: new Prompt({ text: "Fail hosted tool at EOF" }), resume: false })
      response = [
        LLMEvent.stepStart({ index: 0 }),
        LLMEvent.toolCall({
          id: "call-hosted-eof",
          name: "web_search",
          input: { query: "effect" },
          providerExecuted: true,
        }),
      ]

      yield* session.resume(sessionID)
      yield* replaySessionProjection(sessionID)

      expect(yield* session.context(sessionID)).toMatchObject([
        { type: "user", text: "Fail hosted tool at EOF" },
        { type: "assistant", content: [{ type: "tool", id: "call-hosted-eof", state: { status: "error" } }] },
      ])
    }),
  )

  it.effect("durably fails a hosted tool left unresolved by a raw provider stream failure", () =>
    Effect.gen(function* () {
      yield* setup
      const session = yield* SessionV2.Service
      yield* session.prompt({
        sessionID,
        prompt: new Prompt({ text: "Fail hosted tool on raw failure" }),
        resume: false,
      })
      const failure = providerUnavailable()
      responseStream = Stream.concat(
        Stream.fromIterable([
          LLMEvent.stepStart({ index: 0 }),
          LLMEvent.toolCall({
            id: "call-hosted-raw-failure",
            name: "web_search",
            input: { query: "effect" },
            providerExecuted: true,
          }),
        ]),
        Stream.fail(failure),
      )

      expect(yield* session.resume(sessionID).pipe(Effect.flip)).toBe(failure)
      yield* replaySessionProjection(sessionID)
      expect(yield* session.context(sessionID)).toMatchObject([
        { type: "user", text: "Fail hosted tool on raw failure" },
        {
          type: "assistant",
          finish: "error",
          error: { type: "unknown", message: "Provider unavailable" },
          content: [{ type: "tool", id: "call-hosted-raw-failure", state: { status: "error" } }],
        },
      ])
    }),
  )

  it.effect("keeps interleaved assistant text blocks separate", () =>
    Effect.gen(function* () {
      yield* setup
      const session = yield* SessionV2.Service
      yield* session.prompt({ sessionID, prompt: new Prompt({ text: "Two blocks" }), resume: false })

      responses = undefined
      streamGate = undefined
      streamStarted = undefined
      response = [
        LLMEvent.stepStart({ index: 0 }),
        LLMEvent.textStart({ id: "text-1" }),
        LLMEvent.textStart({ id: "text-2" }),
        LLMEvent.textDelta({ id: "text-1", text: "First" }),
        LLMEvent.textDelta({ id: "text-2", text: "Second" }),
        LLMEvent.textEnd({ id: "text-1" }),
        LLMEvent.textEnd({ id: "text-2" }),
        LLMEvent.stepFinish({ index: 0, reason: "stop" }),
        LLMEvent.finish({ reason: "stop" }),
      ]

      yield* session.resume(sessionID)

      expect(yield* session.context(sessionID)).toMatchObject([
        { type: "user", text: "Two blocks" },
        {
          type: "assistant",
          content: [
            { type: "text", id: "text-1", text: "First" },
            { type: "text", id: "text-2", text: "Second" },
          ],
        },
      ])
    }),
  )

  for (const kind of fragmentKinds) {
    it.effect(`broadcasts provider ${kind} deltas without storing projection rewrites`, () =>
      verifyEphemeralDeltas(kind),
    )

    it.effect(`durably closes partial ${kind} when the provider stream fails`, () => verifyPartialFlushOnFailure(kind))

    it.effect(`durably closes partial ${kind} when the provider stream is interrupted`, () =>
      verifyPartialFlushOnInterruption(kind),
    )
  }

  it.effect("rejects duplicate streamed text starts", () =>
    Effect.gen(function* () {
      yield* setup
      const session = yield* SessionV2.Service
      responses = undefined
      streamGate = undefined
      streamStarted = undefined
      response = [LLMEvent.textStart({ id: "text-1" }), LLMEvent.textStart({ id: "text-1" })]

      expect(yield* session.resume(sessionID).pipe(Effect.catchDefect(Effect.succeed))).toBe(
        "Duplicate text start: text-1",
      )
    }),
  )

  it.effect("transitions streamed raw tool input to parsed called input", () =>
    Effect.gen(function* () {
      yield* setup
      const session = yield* SessionV2.Service
      yield* session.prompt({ sessionID, prompt: new Prompt({ text: "Call provider tool" }), resume: false })

      responses = undefined
      streamGate = undefined
      streamStarted = undefined
      response = [
        LLMEvent.stepStart({ index: 0 }),
        LLMEvent.toolInputStart({ id: "call-parsed", name: "web_search" }),
        LLMEvent.toolInputDelta({ id: "call-parsed", name: "web_search", text: '{"query":"hello"}' }),
        LLMEvent.toolInputEnd({ id: "call-parsed", name: "web_search" }),
        LLMEvent.toolCall({ id: "call-parsed", name: "web_search", input: { query: "hello" }, providerExecuted: true }),
      ]

      yield* session.resume(sessionID)

      expect(yield* session.context(sessionID)).toMatchObject([
        { type: "user", text: "Call provider tool" },
        {
          type: "assistant",
          content: [{ type: "tool", id: "call-parsed", state: { status: "error", input: { query: "hello" } } }],
        },
      ])
    }),
  )

  it.effect("rejects malformed streamed tool input ordering", () =>
    Effect.gen(function* () {
      yield* setup
      const session = yield* SessionV2.Service
      responses = undefined
      streamGate = undefined
      streamStarted = undefined
      response = [LLMEvent.toolInputDelta({ id: "call-1", name: "read", text: "{}" })]

      expect(yield* session.resume(sessionID).pipe(Effect.catchDefect(Effect.succeed))).toBe(
        "Tool input delta before start: call-1",
      )
    }),
  )
})