import { createUserMessage, createMessage } from '@deepseek-ai/dsh-llm'
import { describe, expect, it, vi } from 'vitest'
import { Context, type Fiber } from 'cordis'
import SessionStore, { SESSION_FORMAT_VERSION, SessionId } from '@deepseek-ai/dsh-session'
import type { SessionEvent, SessionHeader, SessionId as SessionIdType } from '@deepseek-ai/dsh-session'
import SessionPersistence, { SessionPersistenceRevision } from '@deepseek-ai/dsh-session-persistence'
import SessionQueryService, {
  SESSION_QUERY_DEFAULT_PERSISTED_INSPECT_CONCURRENCY,
  type SessionEventSurface,
  type SessionQueryErrorCode,
} from '@deepseek-ai/dsh-session-query'
import { SessionTitleProviderId } from '@deepseek-ai/dsh-session-title'
import { TestSessionQueryService } from './test-service.ts'

function header(id: string, createdAt = 1, extra: Partial<SessionHeader> = {}): SessionHeader {
  return { version: SESSION_FORMAT_VERSION, id: SessionId(id), createdAt, ...extra }
}

function eventLog(text = 'hello'): SessionEvent[] {
  return [{
    type: 'user/message',
    seq: 0,
    time: 10,
    data: createUserMessage({
      content: [{ type: 'text', text }], source: { kind: 'user' },
    }),
    surfaceOp: 'append',
  }]
}

class TestPersistence extends SessionPersistence {
  static entries = new Map<SessionIdType, { meta: SessionHeader; events: SessionEvent[] }>()
  static listFailure: unknown
  static listOverride: ((signal?: AbortSignal) => Promise<SessionHeader[]>) | undefined
  static inspectFailure: unknown
  static inspectEffect: (() => void) | undefined
  static inspectOverride: ((
    id: SessionIdType,
    signal?: AbortSignal,
  ) => Promise<{ meta: SessionHeader; events: SessionEvent[] }>) | undefined
  static afterList: (() => void) | undefined
  static listCalls = 0
  static inspectCalls: SessionIdType[] = []
  static listSignals: Array<AbortSignal | undefined> = []
  static inspectSignals: Array<AbortSignal | undefined> = []

  static reset(entries: readonly { meta: SessionHeader; events: SessionEvent[] }[] = []): void {
    this.entries = new Map(entries.map(entry => [entry.meta.id, structuredClone(entry)]))
    this.listFailure = undefined
    this.listOverride = undefined
    this.inspectFailure = undefined
    this.inspectEffect = undefined
    this.inspectOverride = undefined
    this.afterList = undefined
    this.listCalls = 0
    this.inspectCalls = []
    this.listSignals = []
    this.inspectSignals = []
  }

  locate(_meta: SessionHeader): undefined {
    return undefined
  }

  create(meta: SessionHeader): Promise<void> {
    TestPersistence.entries.set(meta.id, { meta: structuredClone(meta), events: [] })
    return Promise.resolve()
  }

  append(id: SessionIdType, events: readonly SessionEvent[]): Promise<void> {
    const entry = TestPersistence.entries.get(id)
    if (entry === undefined) return Promise.reject(new Error('missing test session'))
    entry.events.push(...structuredClone(events))
    return Promise.resolve()
  }

  load(id: SessionIdType): Promise<{ meta: SessionHeader; events: SessionEvent[] }> {
    return this.inspect(id)
  }

  inspect(
    id: SessionIdType,
    signal?: AbortSignal,
  ): Promise<{ meta: SessionHeader; events: SessionEvent[] }> {
    TestPersistence.inspectCalls.push(id)
    TestPersistence.inspectSignals.push(signal)
    if (TestPersistence.inspectOverride !== undefined) {
      return TestPersistence.inspectOverride(id, signal)
    }
    if (TestPersistence.inspectFailure !== undefined) return rejectUnknown(TestPersistence.inspectFailure)
    const entry = TestPersistence.entries.get(id)
    if (entry === undefined) return Promise.reject(new Error('missing test session'))
    const result = structuredClone(entry)
    TestPersistence.inspectEffect?.()
    TestPersistence.inspectEffect = undefined
    return Promise.resolve(result)
  }

  async readFrom(id: SessionIdType, fromSeq: number, signal?: AbortSignal): Promise<{ meta: SessionHeader; events: SessionEvent[] }> {
    const whole = await this.inspect(id, signal)
    return { meta: whole.meta, events: whole.events.filter(event => event.seq >= fromSeq) }
  }

  list(signal?: AbortSignal): Promise<SessionHeader[]> {
    TestPersistence.listCalls += 1
    TestPersistence.listSignals.push(signal)
    if (TestPersistence.listOverride !== undefined) return TestPersistence.listOverride(signal)
    if (TestPersistence.listFailure !== undefined) return rejectUnknown(TestPersistence.listFailure)
    const headers = [...TestPersistence.entries.values()].map(entry => structuredClone(entry.meta))
    TestPersistence.afterList?.()
    return Promise.resolve(headers)
  }


  async listSnapshots() {
    return [...TestPersistence.entries.values()].map(entry => ({
      header: structuredClone(entry.meta),
      revision: SessionPersistenceRevision(`events:${entry.events.length}`),
    }))
  }
}

async function liveContext(config: ConstructorParameters<typeof TestSessionQueryService>[1] = {}): Promise<Context> {
  const ctx = new Context()
  await ctx.plugin(SessionStore)
  await ctx.plugin(TestSessionQueryService, config)
  return ctx
}

function expectCode(code: SessionQueryErrorCode): Error {
  return expect.objectContaining({ code }) as Error
}

function rejectUnknown<T>(reason: unknown): Promise<T> {
  return new Promise<T>((_resolve, reject) => {
    // Exercise containment for an implementation that violates the Error rejection convention.
    // eslint-disable-next-line @typescript-eslint/prefer-promise-reject-errors
    reject(reason)
  })
}

const cancellableSessionListings = [
  {
    name: 'listSessions',
    run: (ctx: Context, signal: AbortSignal) => ctx.sessionQuery.listSessions(signal),
  },
  {
    name: 'filterSessions',
    run: (ctx: Context, signal: AbortSignal) => ctx.sessionQuery.filterSessions([], signal),
  },
] as const

interface CancellableExactRead {
  readonly name: 'traceSession' | 'traceEvent' | 'readEvent'
  readonly inspects: boolean
  readonly run: (
    ctx: Context,
    sessionId: SessionIdType,
    signal: AbortSignal,
  ) => Promise<unknown>
}

const cancellableExactReads: readonly CancellableExactRead[] = [
  {
    name: 'traceSession',
    inspects: false,
    run: (ctx, sessionId, signal) => ctx.sessionQuery.traceSession(sessionId, signal),
  },
  {
    name: 'traceEvent',
    inspects: true,
    run: (ctx, sessionId, signal) => ctx.sessionQuery.traceEvent({ sessionId, seq: 0 }, signal),
  },
  {
    name: 'readEvent',
    inspects: true,
    run: (ctx, sessionId, signal) => ctx.sessionQuery.readEvent({ sessionId, seq: 0 }, signal),
  },
] as const

describe.each(cancellableSessionListings)('$name cancellation', ({ run }) => {
  it('preserves an exact pre-abort reason without entering persistence', async () => {
    TestPersistence.reset()
    const ctx = await liveContext()
    await ctx.plugin(TestPersistence)
    const controller = new AbortController()
    const reason = new Error('session listing cancelled before start')
    controller.abort(reason)

    await expect(run(ctx, controller.signal)).rejects.toBe(reason)
    expect(TestPersistence.listCalls).toBe(0)
    expect(TestPersistence.listSignals).toEqual([])
  })

  it('forwards in-flight cancellation and waits for persistence cleanup before rejecting', async () => {
    TestPersistence.reset()
    const ctx = await liveContext()
    await ctx.plugin(TestPersistence)
    const controller = new AbortController()
    const reason = new Error('session listing cancelled in flight')
    const started = Promise.withResolvers<undefined>()
    const abortObserved = Promise.withResolvers<undefined>()
    const cleanup = Promise.withResolvers<undefined>()
    let active = false
    TestPersistence.listOverride = async (signal) => {
      if (signal === undefined) throw new Error('expected persistence listing signal')
      active = true
      const aborted = new Promise<void>((resolve) => {
        signal.addEventListener('abort', () => { resolve() }, { once: true })
      })
      started.resolve(undefined)
      await aborted
      abortObserved.resolve(undefined)
      await cleanup.promise
      active = false
      signal.throwIfAborted()
      return []
    }

    const pending = run(ctx, controller.signal)
    let settled = false
    void pending.then(
      () => { settled = true },
      () => { settled = true },
    )
    await started.promise
    controller.abort(reason)
    await abortObserved.promise

    expect(settled).toBe(false)
    expect(active).toBe(true)
    expect(TestPersistence.listSignals).toEqual([controller.signal])

    cleanup.resolve(undefined)
    await expect(pending).rejects.toBe(reason)
    expect(active).toBe(false)
  })

  it('preserves cancellation after a persistence implementation ignores the signal', async () => {
    TestPersistence.reset()
    const ctx = await liveContext()
    await ctx.plugin(TestPersistence)
    const controller = new AbortController()
    const reason = new Error('session listing cancelled before persistence returned')
    const started = Promise.withResolvers<undefined>()
    const listing = Promise.withResolvers<SessionHeader[]>()
    TestPersistence.listOverride = (_signal) => {
      started.resolve(undefined)
      return listing.promise
    }

    const pending = run(ctx, controller.signal)
    await started.promise
    controller.abort(reason)
    listing.resolve([])

    await expect(pending).rejects.toBe(reason)
    expect(TestPersistence.listSignals).toEqual([controller.signal])
  })
})

describe.each(cancellableExactReads)('$name cancellation', ({ inspects, run }) => {
  it('preserves an exact pre-abort reason without entering persistence', async () => {
    const persisted = header('pre-aborted-exact-read')
    TestPersistence.reset([{ meta: persisted, events: eventLog() }])
    const ctx = await liveContext()
    await ctx.plugin(TestPersistence)
    const controller = new AbortController()
    const reason = new Error('exact read cancelled before start')
    controller.abort(reason)

    await expect(run(ctx, persisted.id, controller.signal)).rejects.toBe(reason)
    expect(TestPersistence.listCalls).toBe(0)
    expect(TestPersistence.inspectCalls).toEqual([])
  })

  it('forwards in-flight list cancellation and waits for cleanup before rejecting', async () => {
    const persisted = header('cancelled-exact-list')
    TestPersistence.reset([{ meta: persisted, events: eventLog() }])
    const ctx = await liveContext()
    await ctx.plugin(TestPersistence)
    const controller = new AbortController()
    const reason = new Error('exact read list cancelled in flight')
    const started = Promise.withResolvers<undefined>()
    const abortObserved = Promise.withResolvers<undefined>()
    const cleanup = Promise.withResolvers<undefined>()
    let active = false
    TestPersistence.listOverride = async (signal) => {
      if (signal === undefined) throw new Error('expected exact-read listing signal')
      active = true
      const aborted = new Promise<void>((resolve) => {
        signal.addEventListener('abort', () => { resolve() }, { once: true })
      })
      started.resolve(undefined)
      await aborted
      abortObserved.resolve(undefined)
      await cleanup.promise
      active = false
      signal.throwIfAborted()
      return []
    }

    const pending = run(ctx, persisted.id, controller.signal)
    let settled = false
    void pending.then(
      () => { settled = true },
      () => { settled = true },
    )
    await started.promise
    controller.abort(reason)
    await abortObserved.promise

    expect(settled).toBe(false)
    expect(active).toBe(true)
    expect(TestPersistence.listSignals).toEqual([controller.signal])
    expect(TestPersistence.inspectCalls).toEqual([])

    cleanup.resolve(undefined)
    await expect(pending).rejects.toBe(reason)
    expect(active).toBe(false)
  })

  it('waits for an ignoring backend to return before preserving the abort reason', async () => {
    const persisted = header('ignored-exact-signal')
    const entry = { meta: persisted, events: eventLog() }
    TestPersistence.reset([entry])
    const ctx = await liveContext()
    await ctx.plugin(TestPersistence)
    const controller = new AbortController()
    const reason = new Error('exact read cancelled while backend ignored signal')
    const started = Promise.withResolvers<undefined>()
    const release = Promise.withResolvers<undefined>()
    let active = false
    if (inspects) {
      TestPersistence.inspectOverride = async () => {
        active = true
        started.resolve(undefined)
        await release.promise
        active = false
        return structuredClone(entry)
      }
    } else {
      TestPersistence.listOverride = async () => {
        active = true
        started.resolve(undefined)
        await release.promise
        active = false
        return [structuredClone(persisted)]
      }
    }

    const pending = run(ctx, persisted.id, controller.signal)
    let settled = false
    void pending.then(
      () => { settled = true },
      () => { settled = true },
    )
    await started.promise
    controller.abort(reason)

    expect(settled).toBe(false)
    expect(active).toBe(true)
    expect(TestPersistence.listSignals).toEqual([controller.signal])
    expect(TestPersistence.inspectSignals).toEqual(inspects ? [controller.signal] : [])

    release.resolve(undefined)
    await expect(pending).rejects.toBe(reason)
    expect(active).toBe(false)
  })
})

describe.each(cancellableExactReads.filter(read => read.inspects))(
  '$name persisted inspection cancellation',
  ({ run }) => {
    it('forwards cancellation and waits for inspection cleanup before rejecting', async () => {
      const persisted = header('cancelled-exact-inspect')
      TestPersistence.reset([{ meta: persisted, events: eventLog() }])
      const ctx = await liveContext()
      await ctx.plugin(TestPersistence)
      const controller = new AbortController()
      const reason = new Error('exact read inspection cancelled in flight')
      const started = Promise.withResolvers<undefined>()
      const abortObserved = Promise.withResolvers<undefined>()
      const cleanup = Promise.withResolvers<undefined>()
      let active = false
      TestPersistence.inspectOverride = async (_sessionId, signal) => {
        if (signal === undefined) throw new Error('expected exact-read inspection signal')
        active = true
        const aborted = new Promise<void>((resolve) => {
          signal.addEventListener('abort', () => { resolve() }, { once: true })
        })
        started.resolve(undefined)
        await aborted
        abortObserved.resolve(undefined)
        await cleanup.promise
        active = false
        signal.throwIfAborted()
        throw new Error('unreachable after exact-read cancellation')
      }

      const pending = run(ctx, persisted.id, controller.signal)
      let settled = false
      void pending.then(
        () => { settled = true },
        () => { settled = true },
      )
      await started.promise
      controller.abort(reason)
      await abortObserved.promise

      expect(settled).toBe(false)
      expect(active).toBe(true)
      expect(TestPersistence.listSignals).toEqual([controller.signal])
      expect(TestPersistence.inspectSignals).toEqual([controller.signal])

      cleanup.resolve(undefined)
      await expect(pending).rejects.toBe(reason)
      expect(active).toBe(false)
    })
  },
)

describe('session-query exact reads', () => {
  it('returns a detached replay-valid full log and rejects a corrupt persisted seed', async () => {
    const valid = header('valid-log', 2)
    const corrupt = header('corrupt-log', 1)
    const validEvents = eventLog('valid')
    const corruptEvents = [{ ...eventLog('bad')[0]!, seq: 1 }]
    TestPersistence.reset([
      { meta: valid, events: validEvents },
      { meta: corrupt, events: corruptEvents },
    ])
    const ctx = await liveContext()
    await ctx.plugin(TestPersistence)

    const snapshot = await ctx.sessionQuery.readSession(valid.id)
    expect(snapshot).toEqual({ session: valid, events: validEvents })
    Object.assign(snapshot.events[0]!, { time: 999 })
    expect(TestPersistence.entries.get(valid.id)?.events[0]?.time).toBe(10)
    await expect(ctx.sessionQuery.readSession(corrupt.id)).rejects.toThrow('seed event at index 0 has seq 1')
  })

  it('prefers a live owner that attaches while its persisted prefix is inspected', async () => {
    const shared = header('attach-during-inspect', 2)
    TestPersistence.reset([{ meta: shared, events: eventLog('persisted') }])
    const ctx = await liveContext()
    await ctx.plugin(TestPersistence)
    TestPersistence.inspectEffect = () => {
      ctx.sessions.create(shared.id, {
        seed: eventLog('live'),
        meta: { createdAt: shared.createdAt },
      })
    }

    await expect(ctx.sessionQuery.filterEvents(shared.id, []))
      .resolves.toMatchObject([{ sessionId: shared.id, text: 'live' }])
  })

  it('reads the latest title from one live-preferred or persisted log without widening listSessions', async () => {
    const persistedHeader = header('persisted-title', 2)
    const sharedHeader = header('shared-title', 3)
    TestPersistence.reset([
      {
        meta: persistedHeader,
        events: [{
          type: 'session/title',
          seq: 0,
          time: 20,
          data: {
            title: 'Persisted title',
            messageSeqs: [4],
            source: { kind: 'fallback' },
          },
        }],
      },
      {
        meta: sharedHeader,
        events: [{
          type: 'session/title',
          seq: 0,
          time: 30,
          data: {
            title: 'Stale durable title',
            messageSeqs: [1],
            source: { kind: 'fallback' },
          },
        }],
      },
    ])
    const ctx = await liveContext()
    const shared = ctx.sessions.create(sharedHeader.id, { meta: { createdAt: 3 } })
    shared.append('session/title', {
      title: 'Live title',
      messageSeqs: [7],
      source: {
        kind: 'provider',
        provider: SessionTitleProviderId('query-test'),
      },
    })
    await ctx.plugin(TestPersistence)

    await expect(ctx.sessionQuery.readTitle(persistedHeader.id)).resolves.toMatchObject({
      title: 'Persisted title', eventSeq: 0, updatedAt: 20,
    })
    await expect(ctx.sessionQuery.readTitle(shared.id)).resolves.toMatchObject({
      title: 'Live title', eventSeq: 0,
    })
    expect(Object.keys((await ctx.sessionQuery.listSessions())[0]!)).toEqual(['header', 'live', 'persisted'])
  })

  it('batches unique persisted title observations through one cancellable corpus scan', async () => {
    const first = header('batch-title-first', 1)
    const second = header('batch-title-second', 2)
    const titleEvent = (title: string, time: number): SessionEvent => ({
      type: 'session/title',
      seq: 0,
      time,
      data: {
        title,
        messageSeqs: [],
        source: { kind: 'fallback' },
      },
    })
    TestPersistence.reset([
      { meta: first, events: [titleEvent('First title', 10)] },
      { meta: second, events: [titleEvent('Second title', 20)] },
    ])
    const ctx = await liveContext()
    await ctx.plugin(TestPersistence)
    const signal = new AbortController().signal
    const missing = SessionId('batch-title-missing')

    const results = await ctx.sessionQuery.readTitleSnapshots(
      [second.id, first.id, second.id, missing],
      signal,
    )

    expect(results.map(result => [result.sessionId, result.status])).toEqual([
      [second.id, 'fulfilled'],
      [first.id, 'fulfilled'],
      [missing, 'rejected'],
    ])
    expect(results[0]).toMatchObject({ value: { session: second, title: { title: 'Second title' } } })
    expect(results[1]).toMatchObject({ value: { session: first, title: { title: 'First title' } } })
    expect(TestPersistence.listCalls).toBe(1)
    expect(TestPersistence.inspectCalls).toEqual([second.id, first.id])
    expect(TestPersistence.listSignals).toEqual([signal])
    expect(TestPersistence.inspectSignals).toEqual([signal, signal])
  })

  it('bounds persisted title inspection concurrency while preserving ordered results', async () => {
    const entries = Array.from({ length: 12 }, (_, index) => {
      const meta = header(`bounded-title-${index}`, index)
      return { meta, events: eventLog(`title-${index}`) }
    })
    TestPersistence.reset(entries)
    const ctx = await liveContext()
    await ctx.plugin(TestPersistence)
    let active = 0
    let maximum = 0
    TestPersistence.inspectOverride = async (id) => {
      active += 1
      maximum = Math.max(maximum, active)
      await new Promise<void>(resolve => setImmediate(resolve))
      active -= 1
      const entry = TestPersistence.entries.get(id)
      if (entry === undefined) throw new Error('missing bounded test session')
      return structuredClone(entry)
    }

    const results = await ctx.sessionQuery.readTitleSnapshots(entries.map(entry => entry.meta.id))

    expect(maximum).toBe(SESSION_QUERY_DEFAULT_PERSISTED_INSPECT_CONCURRENCY)
    expect(TestPersistence.listCalls).toBe(1)
    expect(TestPersistence.inspectCalls).toEqual(entries.map(entry => entry.meta.id))
    expect(results.map(result => result.sessionId)).toEqual(entries.map(entry => entry.meta.id))
    expect(results.every(result => result.status === 'fulfilled')).toBe(true)
  })

  it('folds and discards each completed log before its worker dequeues another inspection', async () => {
    const entries = Array.from({ length: 5 }, (_, index) => ({
      meta: header(`project-title-${index}`, index),
      events: [],
    }))
    TestPersistence.reset(entries)
    const ctx = await liveContext()
    await ctx.plugin(TestPersistence)
    const timeline: string[] = []
    const releases = new Map<SessionIdType, () => void>()
    TestPersistence.inspectOverride = id => new Promise((resolve) => {
      timeline.push(`inspect:${id}`)
      releases.set(id, () => {
        const marker = `full-log-marker:${id}`
        const titleEvent = {
          type: 'session/title',
          seq: 1,
          time: 20,
          data: {
            title: `Projected ${id}`,
            get messageSeqs() {
              timeline.push(`project:${id}`)
              return []
            },
            source: { kind: 'fallback' },
          },
        } as unknown as SessionEvent
        resolve({
          meta: entries.find(entry => entry.meta.id === id)!.meta,
          events: [...eventLog(marker), titleEvent],
        })
      })
    })
    const release = (id: SessionIdType): void => {
      const settle = releases.get(id)
      if (settle === undefined) throw new Error(`inspection ${id} has not started`)
      settle()
    }
    const ids = entries.map(entry => entry.meta.id)

    const pending = ctx.sessionQuery.readTitleSnapshots(ids)
    await vi.waitFor(() => { expect(TestPersistence.inspectCalls).toHaveLength(4) })
    release(ids[0]!)
    await vi.waitFor(() => { expect(TestPersistence.inspectCalls).toHaveLength(5) })

    // Heap-retention assertions would depend on nondeterministic GC. This ordering
    // is the deterministic guard: a retain-all implementation cannot touch the
    // observable title getter until every inspection has completed.
    expect(timeline.indexOf(`project:${ids[0]}`))
      .toBeLessThan(timeline.indexOf(`inspect:${ids[4]}`))
    for (const id of ids.slice(1)) release(id)
    const results = await pending

    expect(results.map(result => result.sessionId)).toEqual(ids)
    expect(JSON.stringify(results)).not.toContain('full-log-marker:')
    expect(results.every(result => result.status === 'fulfilled')).toBe(true)
  })

  it('passes cancellation into a stalled persisted title batch and rejects with its reason', async () => {
    const persisted = header('stalled-title', 1)
    TestPersistence.reset([{ meta: persisted, events: [] }])
    const ctx = await liveContext()
    await ctx.plugin(TestPersistence)
    const controller = new AbortController()
    const reason = new Error('title deadline')
    let started!: () => void
    const inspectStarted = new Promise<void>((resolve) => { started = resolve })
    TestPersistence.inspectOverride = (_id, signal) => new Promise((_resolve, reject) => {
      started()
      signal?.addEventListener('abort', () => { reject(reason) }, { once: true })
    })

    const pending = ctx.sessionQuery.readTitleSnapshots([persisted.id], controller.signal)
    await inspectStarted
    controller.abort(reason)

    await expect(pending).rejects.toBe(reason)
    expect(TestPersistence.listSignals).toEqual([controller.signal])
    expect(TestPersistence.inspectSignals).toEqual([controller.signal])
  })

  it('drains started title inspections after cancellation without starting queued ids', async () => {
    const entries = Array.from({ length: 8 }, (_, index) => ({
      meta: header(`cancel-queued-title-${index}`, index),
      events: eventLog(`queued-${index}`),
    }))
    TestPersistence.reset(entries)
    const persistedInspectConcurrency = 2
    const ctx = await liveContext({ persistedInspectConcurrency })
    await ctx.plugin(TestPersistence)
    const controller = new AbortController()
    const reason = new Error('cancel queued title batch')
    const releases: Array<() => void> = []
    let abortsObserved = 0
    let inspectionsSettled = 0
    TestPersistence.inspectOverride = (_id, signal) => new Promise((_resolve, reject) => {
      signal?.addEventListener('abort', () => { abortsObserved += 1 }, { once: true })
      releases.push(() => {
        inspectionsSettled += 1
        reject(reason)
      })
    })

    const pending = ctx.sessionQuery.readTitleSnapshots(
      entries.map(entry => entry.meta.id),
      controller.signal,
    )
    let batchSettled = false
    void pending.then(
      () => { batchSettled = true },
      () => { batchSettled = true },
    )
    await vi.waitFor(() => {
      expect(TestPersistence.inspectCalls).toHaveLength(persistedInspectConcurrency)
    })
    controller.abort(reason)
    await vi.waitFor(() => { expect(abortsObserved).toBe(persistedInspectConcurrency) })

    expect(batchSettled).toBe(false)
    expect(TestPersistence.inspectCalls)
      .toEqual(entries.slice(0, persistedInspectConcurrency).map(entry => entry.meta.id))
    for (const release of releases) release()

    await expect(pending).rejects.toBe(reason)
    expect(inspectionsSettled).toBe(persistedInspectConcurrency)
    expect(TestPersistence.inspectCalls)
      .toEqual(entries.slice(0, persistedInspectConcurrency).map(entry => entry.meta.id))
  })

  it('passes cancellation into a stalled persisted title listing and rejects with its reason', async () => {
    const persisted = header('stalled-title-list', 1)
    TestPersistence.reset([{ meta: persisted, events: [] }])
    const ctx = await liveContext()
    await ctx.plugin(TestPersistence)
    const controller = new AbortController()
    const reason = new Error('title listing deadline')
    let started!: () => void
    const listStarted = new Promise<void>((resolve) => { started = resolve })
    TestPersistence.listOverride = signal => new Promise((_resolve, reject) => {
      started()
      signal?.addEventListener('abort', () => { reject(reason) }, { once: true })
    })

    const pending = ctx.sessionQuery.readTitleSnapshots([persisted.id], controller.signal)
    await listStarted
    controller.abort(reason)

    await expect(pending).rejects.toBe(reason)
    expect(TestPersistence.listSignals).toEqual([controller.signal])
    expect(TestPersistence.inspectCalls).toEqual([])
  })

  it('isolates title read and fold failures while preferring a live owner attached during inspection', async () => {
    const attached = header('batch-title-attached', 1)
    const failed = header('batch-title-failed', 2)
    const malformed = header('batch-title-malformed', 3)
    const inspectFailure = new Error('one title inspect failed')
    const malformedTitle = {
      type: 'session/title',
      seq: 0,
      time: 30,
      data: {
        title: 'malformed',
        source: { kind: 'fallback' },
      },
    } as unknown as SessionEvent
    TestPersistence.reset([
      { meta: attached, events: eventLog('stale persisted') },
      { meta: failed, events: [] },
      { meta: malformed, events: [malformedTitle] },
    ])
    const ctx = await liveContext()
    await ctx.plugin(TestPersistence)
    TestPersistence.inspectOverride = (id) => {
      if (id === failed.id) return Promise.reject(inspectFailure)
      const entry = TestPersistence.entries.get(id)
      if (entry === undefined) return Promise.reject(new Error('missing test session'))
      if (id === attached.id) {
        const session = ctx.sessions.create(attached.id, { meta: { createdAt: attached.createdAt } })
        session.append('session/title', {
          title: 'Attached live title',
          messageSeqs: [],
          source: { kind: 'fallback' },
        })
      }
      return Promise.resolve(structuredClone(entry))
    }

    const results = await ctx.sessionQuery.readTitleSnapshots([
      attached.id,
      failed.id,
      malformed.id,
    ])

    expect(results[0]).toMatchObject({
      status: 'fulfilled',
      value: { session: attached, title: { title: 'Attached live title' } },
    })
    expect(results[1]).toMatchObject({
      sessionId: failed.id,
      status: 'rejected',
      reason: {
        code: 'SESSION_QUERY_PERSISTENCE_FAILED',
        cause: inspectFailure,
      },
    })
    expect(results[2]).toMatchObject({ sessionId: malformed.id, status: 'rejected' })
    if (results[2]?.status !== 'rejected') throw new Error('expected malformed title rejection')
    expect(results[2].reason).toBeInstanceOf(TypeError)
  })

  it('preserves live batch results across missing persistence, listing failure, and late attachment', async () => {
    const liveOnly = await liveContext()
    const live = liveOnly.sessions.create(SessionId('batch-title-live'))
    const missing = SessionId('batch-title-no-persistence')

    await expect(liveOnly.sessionQuery.readTitleSnapshots([live.id, live.id])).resolves.toEqual([{
      sessionId: live.id,
      status: 'fulfilled',
      value: { session: live.header },
    }])
    await expect(liveOnly.sessionQuery.readTitleSnapshots([live.id, missing])).resolves.toMatchObject([
      { sessionId: live.id, status: 'fulfilled' },
      { sessionId: missing, status: 'rejected' },
    ])
    await expect(liveOnly.sessionQuery.readTitleSnapshot(missing))
      .rejects.toThrow(expectCode('SESSION_QUERY_SESSION_NOT_FOUND'))

    const persisted = header('batch-title-persisted', 1)
    const late = header('batch-title-late', 2)
    TestPersistence.reset([{ meta: persisted, events: [] }])
    const mixed = await liveContext()
    const mixedLive = mixed.sessions.create(SessionId('batch-title-mixed-live'))
    await mixed.plugin(TestPersistence)
    TestPersistence.afterList = () => {
      mixed.sessions.create(late.id, { meta: { createdAt: late.createdAt } })
      TestPersistence.afterList = undefined
    }

    await expect(mixed.sessionQuery.readTitleSnapshots([
      mixedLive.id,
      persisted.id,
      late.id,
    ])).resolves.toMatchObject([
      { sessionId: mixedLive.id, status: 'fulfilled' },
      { sessionId: persisted.id, status: 'fulfilled' },
      { sessionId: late.id, status: 'fulfilled' },
    ])

    TestPersistence.reset()
    TestPersistence.listFailure = new Error('title listing failed')
    const failedList = await liveContext()
    const survivingLive = failedList.sessions.create(SessionId('batch-title-list-live'))
    await failedList.plugin(TestPersistence)

    await expect(failedList.sessionQuery.readTitleSnapshots([survivingLive.id, missing]))
      .resolves.toMatchObject([
        { sessionId: survivingLive.id, status: 'fulfilled' },
        {
          sessionId: missing,
          status: 'rejected',
          reason: expectCode('SESSION_QUERY_PERSISTENCE_FAILED'),
        },
      ])
  })

  it('lists live sessions deterministically and returns detached headers', async () => {
    const ctx = await liveContext()
    const older = ctx.sessions.create(SessionId('older'), { meta: { createdAt: 1 } })
    ctx.sessions.create(SessionId('z'), { meta: { createdAt: 2 } })
    ctx.sessions.create(SessionId('a'), { meta: { createdAt: 2 } })

    const records = await ctx.sessionQuery.listSessions()
    expect(records.map(record => record.header.id)).toEqual([SessionId('a'), SessionId('z'), older.id])
    expect(records.every(record => record.live && !record.persisted)).toBe(true)
    Object.assign(records[2]!.header, { createdAt: 99 })
    expect(older.header.createdAt).toBe(1)
  })

  it('filters sessions symmetrically and owns mutable filter values immediately', async () => {
    const durable = header('durable-filter', 1)
    TestPersistence.reset([{ meta: durable, events: eventLog('durable') }])
    const ctx = await liveContext()
    const live = ctx.sessions.create(SessionId('live-filter'), { meta: { createdAt: 2 } })
    live.append(
      'user/message',
      createUserMessage({
        content: [{ type: 'text', text: 'live' }], source: { kind: 'user' },
      }),
      { surfaceOp: 'append' },
    )
    const persistence = await ctx.plugin(TestPersistence)

    const ids = [durable.id]
    const filtered = ctx.sessionQuery.filterSessions([{ kind: 'id', values: ids }])
    ids[0] = live.id
    await expect(filtered).resolves.toEqual([{
      header: durable,
      live: false,
      persisted: true,
    }])

    const surfaces: SessionEventSurface[] = ['current']
    const events = ctx.sessionQuery.filterEvents(live.id, [{ kind: 'surface', values: surfaces }])
    surfaces[0] = 'shadowed'
    await expect(events).resolves.toMatchObject([{ sessionId: live.id, surface: 'current', text: 'live' }])
    await expect(ctx.sessionQuery.filterSessions([{ kind: 'future' } as never]))
      .rejects.toThrow(expectCode('SESSION_QUERY_INVALID_FILTER'))
    await expect(ctx.sessionQuery.filterEvents(live.id, [{ kind: 'future' } as never]))
      .rejects.toThrow(expectCode('SESSION_QUERY_INVALID_FILTER'))
    await persistence.dispose()
  })

  it('classifies current, shadowed, and raw-log-only events through foldSurface', async () => {
    const ctx = await liveContext()
    const session = ctx.sessions.create(SessionId('surface'))
    session.append('turn/start', { turn: 1, trigger: { kind: 'message', source: { kind: 'user' } } })
    session.append('step/start', { turn: 1, step: 1 })
    const first = session.append(
      'user/message',
      createUserMessage({
        content: [{ type: 'text', text: 'first' }], source: { kind: 'user' },
      }),
      { surfaceOp: 'append' },
    )
    session.append('assistant/chunk', {
      turn: 1,
      step: 1,
      chunk: { type: 'text-delta', index: 0, text: 'draft' },
    })
    session.append(
      'assistant/message',
      {
        turn: 1, step: 1,
        message: createMessage({
          role: 'assistant',
          content: [{ type: 'text', text: 'replacement' }],
          source: {
            kind: 'model',
            ...{ provider: 'mock', model: 'mock' },
          },
        }),
      },
      { surfaceOp: { op: 'replace', start: first.seq, end: first.seq }, sourceEventSeqs: [first.seq] },
    )

    expect((await ctx.sessionQuery.listEvents(session.id)).slice(2).map(record => record.surface))
      .toEqual(['shadowed', 'log-only', 'current'])
  })

  it('reads a detached current surface with its raw-log capture boundary', async () => {
    const ctx = await liveContext()
    const session = ctx.sessions.create(SessionId('surface-snapshot'), { meta: { cwd: '/work' } })
    const first = session.append(
      'user/message',
      createUserMessage({
        content: [{ type: 'text', text: 'old' }], source: { kind: 'user' },
      }),
      { surfaceOp: 'append' },
    )
    session.append('assistant/chunk', {
      turn: 1,
      step: 1,
      chunk: { type: 'text-delta', index: 0, text: 'draft' },
    })
    session.append(
      'user/message',
      createUserMessage({
        content: [{ type: 'text', text: 'checkpoint' }], source: { kind: 'plugin', plugin: 'compact' },
      }),
      { surfaceOp: { op: 'replace', start: first.seq, end: first.seq }, sourceEventSeqs: [first.seq] },
    )
    const retained = session.append(
      'user/message',
      createUserMessage({
        content: [{ type: 'text', text: 'retained tail' }], source: { kind: 'user' },
      }),
      { surfaceOp: 'append' },
    )
    session.append(
      'user/message',
      createUserMessage({
        content: [{ type: 'text', text: 'latest checkpoint' }], source: { kind: 'plugin', plugin: 'compact' },
      }),
      { surfaceOp: { op: 'replace', start: 2, end: retained.seq }, sourceEventSeqs: [2, retained.seq] },
    )
    session.append(
      'assistant/message',
      {
        turn: 2, step: 1,
        message: createMessage({
          role: 'assistant',
          content: [{ type: 'text', text: 'latest answer' }],
          source: {
            kind: 'model',
            ...{ provider: 'mock', model: 'mock' },
          },
        }),
      },
      { surfaceOp: 'append' },
    )

    const snapshot = await ctx.sessionQuery.readSurface(session.id)
    expect(snapshot.session).toEqual(session.header)
    expect(snapshot.capturedThroughSeq).toBe(5)
    expect(snapshot.events.map(event => [event.seq, event.type])).toEqual([
      [4, 'user/message'],
      [5, 'assistant/message'],
    ])
    if (snapshot.events[0]?.type !== 'user/message') throw new Error('expected current user message')
    expect(() => {
      (snapshot.events[0]!.data as { content: unknown[] }).content = []
    }).toThrow()
    Object.assign(snapshot.session, { cwd: '/mutated' })

    expect(session.events[4]?.type === 'user/message' && session.events[4].data.content).toHaveLength(1)
    expect(session.header.cwd).toBe('/work')
  })

  it('returns an empty current surface with a null capture boundary', async () => {
    const ctx = await liveContext()
    const session = ctx.sessions.create(SessionId('empty-surface'))
    await expect(ctx.sessionQuery.readSurface(session.id)).resolves.toMatchObject({
      capturedThroughSeq: null,
      events: [],
    })
  })

  it('returns a bounded detached raw-event window and validates the request', async () => {
    const ctx = await liveContext({ readWindowMax: 1 })
    const session = ctx.sessions.create(SessionId('window'), { meta: { cwd: '/work' } })
    session.append('turn/start', { turn: 1, trigger: { kind: 'message', source: { kind: 'user' } } })
    for (const text of ['one', 'two', 'three']) {
      session.append(
        'user/message',
        createUserMessage({
          content: [{ type: 'text', text }], source: { kind: 'user' },
        }),
        { surfaceOp: 'append' },
      )
    }

    const result = await ctx.sessionQuery.readEvent({ sessionId: session.id, seq: 2, before: 1, after: 1 })
    expect([result.startSeq, result.endSeq, result.target.seq]).toEqual([1, 3, 2])
    expect(result.session).toEqual(session.header)
    Object.assign(result.session, { createdAt: -1 })
    if (result.events[0]?.type !== 'user/message') throw new Error('expected user message')
    expect(() => {
      (result.events[0]!.data as { content: unknown[] }).content = []
    }).toThrow()
    expect(session.header.createdAt).not.toBe(-1)
    expect(session.events[1]?.type === 'user/message' && session.events[1].data.content).toHaveLength(1)

    await expect(ctx.sessionQuery.readEvent({ sessionId: session.id, seq: 9 }))
      .rejects.toThrow(expectCode('SESSION_QUERY_EVENT_NOT_FOUND'))
    for (const request of [
      { sessionId: session.id, seq: 0, before: -1 },
      { sessionId: session.id, seq: 0, before: 2 },
      { sessionId: session.id, seq: 0, after: 0.5 },
    ]) {
      await expect(ctx.sessionQuery.readEvent(request)).rejects.toThrow(expectCode('SESSION_QUERY_INVALID_WINDOW'))
    }
  })

  it('merges authoritative persistence with live precedence and detects conflicts', async () => {
    const shared = header('shared', 3, { cwd: '/same' })
    const durable = header('durable', 2)
    TestPersistence.reset([
      { meta: shared, events: eventLog('persisted') },
      { meta: durable, events: eventLog('durable') },
    ])
    const ctx = await liveContext()
    const live = ctx.sessions.create(shared.id, { meta: { createdAt: 3, cwd: '/same' } })
    live.append('turn/start', { turn: 1, trigger: { kind: 'message', source: { kind: 'user' } } })
    live.append(
      'user/message',
      createUserMessage({
        content: [{ type: 'text', text: 'live' }], source: { kind: 'user' },
      }),
      { surfaceOp: 'append' },
    )
    const persistence = await ctx.plugin(TestPersistence)

    expect((await ctx.sessionQuery.listSessions()).map(record => [record.header.id, record.live, record.persisted]))
      .toEqual([[shared.id, true, true], [durable.id, false, true]])
    const liveRead = await ctx.sessionQuery.readEvent({ sessionId: shared.id, seq: 1 })
    expect(liveRead.target.type === 'user/message' && liveRead.target.data.content[0])
      .toMatchObject({ text: 'live' })
    await expect(ctx.sessionQuery.readSurface(shared.id)).resolves.toMatchObject({
      events: [{ data: { content: [{ text: 'live' }] } }],
    })
    await expect(ctx.sessionQuery.readEvent({ sessionId: durable.id, seq: 0 }))
      .resolves.toMatchObject({ session: durable })
    await expect(ctx.sessionQuery.readSurface(durable.id)).resolves.toMatchObject({
      session: durable,
      events: [{ data: { content: [{ text: 'durable' }] } }],
    })

    const sharedEntry = TestPersistence.entries.get(shared.id)!
    sharedEntry.meta = { ...sharedEntry.meta, cwd: '/conflict' }
    await expect(ctx.sessionQuery.listSessions()).rejects.toThrow(expectCode('SESSION_QUERY_SOURCE_CONFLICT'))
    sharedEntry.meta = { ...sharedEntry.meta, cwd: '/same', delegationDepth: 1 }
    await expect(ctx.sessionQuery.listSessions()).rejects.toThrow(expectCode('SESSION_QUERY_SOURCE_CONFLICT'))
    await persistence.dispose()
    await expect(ctx.sessionQuery.listSessions()).resolves.toEqual([
      { header: shared, live: true, persisted: false },
    ])
  })

  it('keeps known live reads independent from persistence health', async () => {
    TestPersistence.reset()
    const ctx = await liveContext()
    const live = ctx.sessions.create(SessionId('live'))
    live.append('turn/start', { turn: 1, trigger: { kind: 'message', source: { kind: 'user' } } })
    live.append(
      'user/message',
      createUserMessage({
        content: [{ type: 'text', text: 'available' }], source: { kind: 'user' },
      }),
      { surfaceOp: 'append' },
    )
    await ctx.plugin(TestPersistence)
    TestPersistence.listFailure = new Error('list unavailable')
    TestPersistence.inspectFailure = new Error('inspect unavailable')
    const signal = new AbortController().signal

    await expect(ctx.sessionQuery.listEvents(live.id)).resolves.toHaveLength(2)
    await expect(ctx.sessionQuery.traceEvent({ sessionId: live.id, seq: 1 }, signal))
      .resolves.toMatchObject({ session: { id: live.id }, target: { seq: 1 } })
    await expect(ctx.sessionQuery.readEvent({ sessionId: live.id, seq: 1 }, signal))
      .resolves.toMatchObject({ target: { seq: 1 } })
    expect(TestPersistence.listSignals).toEqual([])
    expect(TestPersistence.inspectSignals).toEqual([])
    await expect(ctx.sessionQuery.listSessions()).rejects.toThrow(expectCode('SESSION_QUERY_PERSISTENCE_FAILED'))
    await expect(ctx.sessionQuery.listEvents(SessionId('durable'))).rejects.toThrow(expectCode('SESSION_QUERY_PERSISTENCE_FAILED'))
  })

  it('reports absent sessions, persisted load failures, and persisted header conflicts', async () => {
    const durable = header('durable')
    TestPersistence.reset([{ meta: durable, events: eventLog() }])
    const ctx = await liveContext()
    await expect(ctx.sessionQuery.listEvents(SessionId('absent')))
      .rejects.toThrow(expectCode('SESSION_QUERY_SESSION_NOT_FOUND'))
    await ctx.plugin(TestPersistence)
    await expect(ctx.sessionQuery.listEvents(SessionId('absent')))
      .rejects.toThrow(expectCode('SESSION_QUERY_SESSION_NOT_FOUND'))

    TestPersistence.inspectFailure = 'raw failure'
    await expect(ctx.sessionQuery.listEvents(durable.id))
      .rejects.toThrow(expectCode('SESSION_QUERY_PERSISTENCE_FAILED'))
    TestPersistence.inspectFailure = undefined
    const durableEntry = TestPersistence.entries.get(durable.id)!
    durableEntry.meta = { ...durableEntry.meta, cwd: '/changed-after-list' }
    TestPersistence.afterList = () => {
      const listedEntry = TestPersistence.entries.get(durable.id)!
      listedEntry.meta = { ...listedEntry.meta, cwd: '/changed-during-read' }
    }
    await expect(ctx.sessionQuery.listEvents(durable.id))
      .rejects.toThrow(expectCode('SESSION_QUERY_SOURCE_CONFLICT'))
  })

  it('turns persisted malformed surfaces and direct invalid config into typed errors', async () => {
    const ctx = await liveContext()
    const persisted = header('bad-persisted-surface')
    TestPersistence.reset([{
      meta: persisted,
      events: [{
        type: 'user/message',
        seq: 0,
        time: 1,
        data: createUserMessage({
          content: [{ type: 'text', text: 'hidden' }], source: { kind: 'user' },
        }),
      }],
    }])
    const persistence = await ctx.plugin(TestPersistence)
    await expect(ctx.sessionQuery.listEvents(persisted.id))
      .rejects.toThrow(expectCode('SESSION_QUERY_INVALID_SURFACE'))
    await persistence.dispose()

    const direct = new Context()
    await direct.plugin(SessionStore)
    expect(new TestSessionQueryService(direct)).toBeInstanceOf(SessionQueryService)
    for (const config of [
      { readWindowMax: -1 },
      { persistedInspectConcurrency: 0 },
      { persistedInspectConcurrency: Number.MAX_SAFE_INTEGER + 1 },
    ]) {
      const invalid = new Context()
      await invalid.plugin(SessionStore)
      expect(() => new TestSessionQueryService(invalid, config))
        .toThrow(expectCode('SESSION_QUERY_INVALID_CONFIG'))
    }
  })

  it('leaves the optional persistence dependency optional', async () => {
    const ctx = new Context()
    await ctx.plugin(SessionStore)
    const fiber = await ctx.plugin(TestSessionQueryService)
    expect(ctx.sessionQuery).toBeInstanceOf(TestSessionQueryService)
    await fiber.dispose()
    expect(ctx.sessionQuery).toBeUndefined()
  })

  it('awaits optional-persistence child-fiber quiescence on disposal', async () => {
    TestPersistence.reset()
    const ctx = new Context()
    await ctx.plugin(SessionStore)
    const query = await ctx.plugin(TestSessionQueryService)
    const persistence = await ctx.plugin(TestPersistence)
    const optional = (ctx.sessionQuery as unknown as {
      _corpus: { _optionalPersistenceFiber: Fiber }
    })._corpus._optionalPersistenceFiber
    let release!: () => void
    const cleanup = new Promise<void>((resolve) => { release = resolve })
    optional.ctx.effect(() => () => cleanup)

    let settled = false
    const disposing = query.dispose().then(() => { settled = true })
    await Promise.resolve()
    expect(settled).toBe(false)
    release()
    await disposing
    await persistence.dispose()
  })
})
