/**
 * SessionManager orchestration: lazy resident instances, list lifecycle, host
 * frame routing, and the pending-frame buffer for uninstantiated sessions.
 */

import { describe, expect, it, vi } from 'vitest'
import type { SessionId } from '@deepseek-ai/dsh-client-connection/client'
import { SessionManager } from '../src/client/sessions/manager.ts'
import { FakeApiClient, deferred, err, ok } from './fake-api.ts'
import { entries, plainTurn } from './event-script.ts'

const S1 = 'fk-m1' as SessionId
const S2 = 'fk-m2' as SessionId

type SummaryOver = Partial<{
  updatedAt: number
  running: boolean
  blank: boolean
  parentSessionId: SessionId
  origin: 'subagent'
}>

function summary(sessionId: SessionId, over: SummaryOver = {}) {
  return { sessionId, updatedAt: 100, running: false, blank: false, ...over }
}

describe('instances', () => {
  it('lazily builds one resident instance per id and syncs the running bit from the list', async () => {
    const api = new FakeApiClient()
    api.onList = () => Promise.resolve(ok({ items: [summary(S1, { running: true })] as never[] }))
    const manager = new SessionManager(api)
    await manager.refreshList()
    const session = manager.get(S1)
    expect(manager.get(S1)).toBe(session) // resident: same instance forever
    expect(session.getSnapshot().running).toBe(true) // list preceded instantiation
  })

  it('replays buffered approval frames on instantiation and drops ordinary frames for uninstantiated sessions', () => {
    const api = new FakeApiClient()
    const manager = new SessionManager(api)
    // Uninstantiated: approval buffers, plain session/event drops.
    manager.handleMuxEnvelope({ rpcId: 'ra' as never, payload: { type: 'approval/requested', sessionId: S1, approvalId: 'ap1' as never, toolName: 'rm' } })
    manager.handleMuxEnvelope({ rpcId: 'ra' as never, payload: { type: 'approval/requested', sessionId: S1, approvalId: 'ap1' as never, toolName: 'rm' } })
    manager.handleMuxEnvelope({ rpcId: 're' as never, payload: { type: 'session/event', sessionId: S1, event: plainTurn(0, 0, 'x', 'y')[0] as never } })
    const session = manager.get(S1)
    expect(session.getSnapshot().pending).toMatchObject([{ kind: 'approval', payload: { approvalId: 'ap1' } }])
    // Buffer cleared: a second instantiation of another id gets nothing.
    expect(manager.get(S2).getSnapshot().pending).toEqual([])
  })

  it('retains every live answerable request and compacts resolutions before instantiation', () => {
    const api = new FakeApiClient()
    const manager = new SessionManager(api)
    manager.handleHostEnvelope({ rpcId: 'h1' as never, payload: { type: 'host/session-added', sessionId: S1, blank: false } })
    for (let i = 0; i < 40; i++) {
      manager.handleMuxEnvelope({ rpcId: `q${i}` as never, payload: { type: 'question/requested', sessionId: S1, questions: [] } })
    }
    expect(manager.getListSnapshot().items[0]?.pendingInteraction).toBe('question')
    for (let i = 0; i < 40; i++) {
      manager.handleMuxEnvelope({
        rpcId: `r${i}` as never,
        payload: { type: 'question/resolved', sessionId: S1, questionRpcId: `q${i}` as never, outcome: 'answered' },
      })
    }
    expect(manager.getListSnapshot().items[0]?.pendingInteraction).toBeUndefined()
    expect(manager.get(S1).getSnapshot().pending).toEqual([])
  })

  it('drops buffered answerable requests on session removal', () => {
    const manager = new SessionManager(new FakeApiClient())
    // Removed session: buffered frames must not replay on a future instantiation.
    manager.handleMuxEnvelope({ rpcId: 'qz' as never, payload: { type: 'question/requested', sessionId: S2, questions: [] } })
    manager.handleHostEnvelope({ rpcId: 'hz' as never, payload: { type: 'host/session-removed', sessionId: S2 } })
    expect(manager.get(S2).getSnapshot().pending).toEqual([])
  })
})

describe('list lifecycle', () => {
  it('single-flights refreshList and preserves the Host baseline order', async () => {
    const api = new FakeApiClient()
    const gate = deferred<Awaited<ReturnType<FakeApiClient['onList']>>>()
    api.onList = () => gate.promise
    const manager = new SessionManager(api)
    const first = manager.refreshList()
    const second = manager.refreshList()
    expect(manager.getListSnapshot().state).toBe('loading')
    gate.resolve(ok({ items: [summary(S2, { updatedAt: 200 }), summary(S1)] as never[] }))
    await Promise.all([first, second])
    expect(api.callsOf('session.list')).toHaveLength(1)
    const snapshot = manager.getListSnapshot()
    expect(snapshot.state).toBe('idle')
    expect(snapshot.items.map(i => i.sessionId)).toEqual([S2, S1])
  })

  it('replays incremental frames over hydration and never batch-reorders established ids', async () => {
    const api = new FakeApiClient()
    const first = deferred<Awaited<ReturnType<FakeApiClient['onList']>>>()
    api.onList = () => first.promise
    const manager = new SessionManager(api)
    const hydration = manager.refreshList()
    manager.handleHostEnvelope({
      rpcId: 'during-first' as never,
      payload: { type: 'host/session-added', blank: true, sessionId: S2 },
    })
    first.resolve(ok({ items: [summary(S1)] as never[] }))
    await hydration
    expect(manager.getListSnapshot().items.map(item => item.sessionId)).toEqual([S2, S1])

    api.onList = () => Promise.resolve(ok({
      items: [summary(S1, { updatedAt: 900 }), summary(S2, { updatedAt: 800 })] as never[],
    }))
    await manager.refreshList()
    expect(manager.getListSnapshot().items.map(item => item.sessionId)).toEqual([S2, S1])
  })

  it('keeps the error in the list snapshot on failure', async () => {
    const api = new FakeApiClient()
    api.onList = () => Promise.resolve(err({ code: 'internal', message: 'boom', details: {} }))
    const manager = new SessionManager(api)
    await manager.refreshList()
    expect(manager.getListSnapshot()).toMatchObject({ state: 'error', error: { code: 'internal' } })
    // A failed pull does not step the arrival phase: still pending.
    expect(manager.getListSnapshot().phase).toBe('pending')
  })

  it('phase steps pending → ready on the first successful pull and never returns', async () => {
    const api = new FakeApiClient()
    const manager = new SessionManager(api)
    expect(manager.getListSnapshot().phase).toBe('pending')
    await manager.refreshList()
    expect(manager.getListSnapshot().phase).toBe('ready')
    // Sticky across later failures: the pull-activity axis reports the error,
    // the arrival phase holds.
    api.onList = () => Promise.resolve(err({ code: 'internal', message: 'down', details: {} }))
    await manager.refreshList()
    expect(manager.getListSnapshot()).toMatchObject({ state: 'error', phase: 'ready' })
    // And across an empty re-pull (empty-with-ready = truly no sessions).
    api.onList = () => Promise.resolve(ok({ items: [] as never[] }))
    await manager.refreshList()
    expect(manager.getListSnapshot()).toMatchObject({ state: 'idle', phase: 'ready' })
    expect(manager.getListSnapshot().items).toEqual([])
  })

  it('merges create into the list immediately without waiting for a refresh', async () => {
    const api = new FakeApiClient()
    api.onCreate = () => Promise.resolve(ok({ sessionId: S2 }))
    const manager = new SessionManager(api)
    const result = await manager.create()
    expect(result).toMatchObject({ ok: true, value: { sessionId: S2 } })
    expect(manager.getListSnapshot().items.map(i => i.sessionId)).toEqual([S2])
  })

  it('retains title projections before list arrival, keeps last-wins by seq, and clears them on removal', async () => {
    const api = new FakeApiClient()
    const manager = new SessionManager(api)
    const titleFrame = (rpcId: string, title: string, seq: number) => {
      manager.handleMuxEnvelope({
        rpcId: rpcId as never,
        payload: { type: 'session/projection', sessionId: S1, key: 'title', value: title, seq } as never,
      })
    }
    titleFrame('title-new', 'Newest', 4)
    titleFrame('title-stale', 'Stale', 3)
    titleFrame('title-equal', 'Equal', 4)
    api.onList = () => Promise.resolve(ok({
      items: [summary(S1), summary(S2, { updatedAt: 200 })] as never[],
    }))
    await manager.refreshList()

    const titled = manager.getListSnapshot()
    expect(titled.items.map(item => item.sessionId)).toEqual([S1, S2])
    expect(titled.items[0]?.title).toBe('Newest')
    expect(titled.items[1]?.title).toBeUndefined()

    manager.handleHostEnvelope({ rpcId: 'removed' as never, payload: { type: 'host/session-removed', sessionId: S1 } })
    manager.handleHostEnvelope({ rpcId: 'readded' as never, payload: { type: 'host/session-added', blank: true, sessionId: S1 } })
    expect(manager.getListSnapshot().items.find(item => item.sessionId === S1)?.title).toBeUndefined()
  })

  it('seeds cold titles from the list rows\' projections block under higher-seq-wins', async () => {
    const api = new FakeApiClient()
    const manager = new SessionManager(api)
    // A push frame landed before the list (S2's title is newer than the block's cut).
    manager.handleMuxEnvelope({
      rpcId: 'push-newer' as never,
      payload: { type: 'session/projection', sessionId: S2, key: 'title', value: 'Pushed', seq: 9 } as never,
    })
    api.onList = () => Promise.resolve(ok({
      items: [
        { ...summary(S1), projections: { asOfSeq: 4, values: { title: 'Cold cached' } } },
        { ...summary(S2, { updatedAt: 200 }), projections: { asOfSeq: 5, values: { title: 'List stale' } } },
      ] as never[],
    }))
    await manager.refreshList()
    const items = manager.getListSnapshot().items
    // Cold row: title surfaces straight from the list block — no open, no history.
    expect(items.find(item => item.sessionId === S1)?.title).toBe('Cold cached')
    // The stale list block (seq 5) cannot overwrite the newer push frame (seq 9).
    expect(items.find(item => item.sessionId === S2)?.title).toBe('Pushed')
  })

  it('drops a projection row beyond the subscription baseline before accepting its durable replay', async () => {
    const api = new FakeApiClient()
    api.onList = () => Promise.resolve(ok({ items: [summary(S1)] as never[] }))
    const manager = new SessionManager(api)
    await manager.refreshList()
    const frame = (rpcId: string, payload: object) => {
      manager.handleMuxEnvelope({ rpcId: rpcId as never, payload: payload as never })
    }
    frame('title-unflushed', { type: 'session/projection', sessionId: S1, key: 'title', value: 'Unflushed', seq: 4 })

    // The durable baseline says the host only knows up to seq 2: the phantom
    // row rode lost state and must drop, or last-wins pins it forever.
    frame('subscribed-recovered', { type: 'session/subscribed', sessionId: S1, lastSeq: 2 })
    expect(manager.getListSnapshot().items[0]?.title).toBeUndefined()

    frame('title-durable', { type: 'session/projection', sessionId: S1, key: 'title', value: 'Durable', seq: 2 })
    expect(manager.getListSnapshot().items[0]?.title).toBe('Durable')

    // A baseline at or past the row's seq keeps it (nothing phantom to drop).
    frame('subscribed-current', { type: 'session/subscribed', sessionId: S1, lastSeq: 2 })
    expect(manager.getListSnapshot().items[0]?.title).toBe('Durable')
  })
})

describe('search', () => {
  it('returns bounded Host results and forwards the caller signal', async () => {
    const api = new FakeApiClient()
    api.onSearch = () => Promise.resolve(ok({
      items: [{ sessionId: S1, snippet: 'matching excerpt' }],
      hasMore: true,
    }))
    const manager = new SessionManager(api)
    const signal = new AbortController().signal

    await expect(manager.search('exact phrase', signal)).resolves.toEqual({
      ok: true,
      value: {
        items: [{ sessionId: S1, snippet: 'matching excerpt' }],
        hasMore: true,
      },
    })
    expect(api.callsOf('session.search')).toEqual([{ query: 'exact phrase' }])
    expect(api.lastSearchSignal).toBe(signal)
  })

  it('preserves business errors and folds transport failures', async () => {
    const api = new FakeApiClient()
    const manager = new SessionManager(api)
    api.onSearch = () => Promise.resolve(err({
      code: 'internal',
      message: 'index unavailable',
      details: {},
    }))
    const signal = new AbortController().signal
    await expect(manager.search('first', signal)).resolves.toMatchObject({
      ok: false,
      error: { code: 'internal', message: 'index unavailable' },
    })

    api.onSearch = () => Promise.reject(new Error('wire down'))
    await expect(manager.search('second', signal)).resolves.toMatchObject({
      ok: false,
      error: { code: 'internal', message: 'wire down' },
    })
  })
})

describe('host frame routing', () => {
  it('adds/removes/flips sessions from host frames and keeps removed instances resident', async () => {
    const api = new FakeApiClient()
    const manager = new SessionManager(api)
    manager.handleHostEnvelope({ rpcId: 'h1' as never, payload: { type: 'host/session-added', blank: true, sessionId: S1 } })
    manager.handleHostEnvelope({ rpcId: 'h2' as never, payload: { type: 'host/session-added', blank: true, sessionId: S1 } }) // dup: ignored
    expect(manager.getListSnapshot().items).toHaveLength(1)

    const session = manager.get(S1)
    manager.handleHostEnvelope({ rpcId: 'h3' as never, payload: { type: 'host/session-status', sessionId: S1, running: true } })
    expect(session.getSnapshot().running).toBe(true)
    expect(manager.getListSnapshot().items[0]?.running).toBe(true)

    manager.handleHostEnvelope({ rpcId: 'h4' as never, payload: { type: 'host/agent-error', sessionId: S1, message: '炸了' } })
    expect(session.getSnapshot().lastAgentError).toBe('炸了')

    manager.handleHostEnvelope({ rpcId: 'h5' as never, payload: { type: 'host/session-removed', sessionId: S1 } })
    expect(manager.getListSnapshot().items).toHaveLength(0)
    expect(session.getSnapshot().removed).toBe(true)
    expect(manager.get(S1)).toBe(session) // resident-instance rule survives removal
  })
})

describe('subagent catalogs', () => {
  it('keeps a catalog-discovered child address across ordinary selection and status frames', async () => {
    const api = new FakeApiClient()
    api.onList = () => Promise.resolve(ok({ items: [
      summary(S1),
      summary(S2, { parentSessionId: S1, origin: 'subagent' }),
    ] as never[] }))
    api.onSubagentList = () => Promise.resolve(ok({
      entries: [{
        kind: 'child', id: S2, mode: 'continuable', label: 'worker',
        activity: 'running', hasChildren: false,
      }] as never[],
      parentAvailable: true,
    }))
    const manager = new SessionManager(api)
    await manager.refreshList()
    await manager.refreshSubagents(S1)
    manager.selectSubagent({ parentSessionId: S1, childSessionId: S2, mode: 'continuable' })

    expect(manager.getListSnapshot().currentAddress).toEqual({
      parentSessionId: S1, childSessionId: S2, mode: 'continuable',
    })
    expect(manager.get(S2).getSnapshot().subagent).toEqual({
      address: { parentSessionId: S1, childSessionId: S2, mode: 'continuable' },
      parentAvailable: true,
    })
    // Clicking the same child through an ordinary list-selection path must not
    // erase the catalog-derived address and fall back to session.* transport.
    manager.select(S2)
    expect(manager.getListSnapshot().currentAddress).toEqual({
      parentSessionId: S1, childSessionId: S2, mode: 'continuable',
    })
    expect(manager.get(S2).getSnapshot().subagent).toEqual({
      address: { parentSessionId: S1, childSessionId: S2, mode: 'continuable' },
      parentAvailable: true,
    })
    await manager.get(S2).open()
    await manager.get(S2).prompt([{ type: 'text', text: 'continue' }], 'queue')
    expect(api.callsOf('subagent.history')).toEqual([
      { parentSessionId: S1, childSessionId: S2, mode: 'continuable', maxMessages: 50 },
    ])
    expect(api.callsOf('subagent.prompt')).toEqual([
      {
        parentSessionId: S1, childSessionId: S2, mode: 'continuable',
        content: [{ type: 'text', text: 'continue' }],
      },
    ])
    expect(api.callsOf('session.history')).toEqual([])
    expect(api.callsOf('session.prompt')).toEqual([])
    const listCalls = api.callsOf('subagent.list').length
    manager.handleHostEnvelope({
      rpcId: 'child-complete' as never,
      payload: { type: 'host/session-status', sessionId: S2, running: false },
    })
    expect(manager.getListSnapshot().subagentsByParent[S1]?.entries[0]).toMatchObject({
      kind: 'child', id: S2, activity: 'inactive',
    })
    expect(api.callsOf('subagent.list')).toHaveLength(listCalls)

    manager.handleHostEnvelope({
      rpcId: 'child-detached' as never,
      payload: { type: 'host/session-removed', sessionId: S2 },
    })
    expect(manager.getListSnapshot().items.find(item => item.sessionId === S2)).toMatchObject({
      origin: 'subagent', parentSessionId: S1, running: false,
    })
    expect(manager.get(S2).getSnapshot()).toMatchObject({
      removed: false,
      subagent: {
        address: { parentSessionId: S1, childSessionId: S2, mode: 'continuable' },
      },
    })
  })

  it('refetches debounced membership only while the parent catalog is open', async () => {
    vi.useFakeTimers()
    try {
      const api = new FakeApiClient()
      const manager = new SessionManager(api)
      await manager.refreshSubagents(S1)
      manager.setSubagentCatalogOpen(S1, true)
      await Promise.resolve()
      const baseline = api.callsOf('subagent.list').length
      manager.handleHostEnvelope({
        rpcId: 'child-added' as never,
        payload: {
          type: 'host/session-added', sessionId: S2, parentSessionId: S1, blank: false,
        },
      })
      manager.handleHostEnvelope({
        rpcId: 'child-added-again' as never,
        payload: {
          type: 'host/session-added', sessionId: 'fk-m3' as SessionId, parentSessionId: S1, blank: false,
        },
      })
      await vi.advanceTimersByTimeAsync(50)
      expect(api.callsOf('subagent.list')).toHaveLength(baseline + 1)

      manager.setSubagentCatalogOpen(S1, false)
      manager.handleHostEnvelope({
        rpcId: 'child-added-closed' as never,
        payload: {
          type: 'host/session-added', sessionId: 'fk-m4' as SessionId, parentSessionId: S1, blank: false,
        },
      })
      await vi.advanceTimersByTimeAsync(50)
      expect(api.callsOf('subagent.list')).toHaveLength(baseline + 1)
    } finally {
      vi.useRealTimers()
    }
  })

  it('marks a loaded parent row expandable only for a direct subagent publication', async () => {
    const api = new FakeApiClient()
    const root = 'fk-root' as SessionId
    api.onSubagentList = () => Promise.resolve(ok({
      entries: [
        {
          kind: 'child', id: S1, mode: 'continuable', label: 'parent',
          activity: 'inactive', hasChildren: false,
        },
        {
          kind: 'child', id: S2, mode: 'continuable', label: 'ordinary parent',
          activity: 'inactive', hasChildren: false,
        },
      ] as never[],
      parentAvailable: true,
    }))
    const manager = new SessionManager(api)
    await manager.refreshSubagents(root)

    manager.handleHostEnvelope({
      rpcId: 'nested-subagent' as never,
      payload: {
        type: 'host/session-added', sessionId: 'fk-grandchild' as SessionId,
        parentSessionId: S1, origin: 'subagent', blank: false,
      },
    })
    manager.handleHostEnvelope({
      rpcId: 'ordinary-fork' as never,
      payload: {
        type: 'host/session-added', sessionId: 'fk-fork' as SessionId,
        parentSessionId: S2, blank: false,
      },
    })

    expect(manager.getListSnapshot().subagentsByParent[root]?.entries).toMatchObject([
      { kind: 'child', id: S1, hasChildren: true },
      { kind: 'child', id: S2, hasChildren: false },
    ])
  })

  it('preserves a live expandability hint across only the older in-flight catalog response', async () => {
    const api = new FakeApiClient()
    const root = 'fk-root' as SessionId
    const response = deferred<Awaited<ReturnType<FakeApiClient['onSubagentList']>>>()
    api.onSubagentList = () => response.promise
    const manager = new SessionManager(api)
    const refresh = manager.refreshSubagents(root)

    manager.handleHostEnvelope({
      rpcId: 'nested-subagent' as never,
      payload: {
        type: 'host/session-added', sessionId: 'fk-grandchild' as SessionId,
        parentSessionId: S1, origin: 'subagent', blank: false,
      },
    })
    response.resolve(ok({
      entries: [{
        kind: 'child', id: S1, mode: 'continuable', label: 'parent',
        activity: 'inactive', hasChildren: false,
      }] as never[],
      parentAvailable: true,
    }))
    await refresh

    expect(manager.getListSnapshot().subagentsByParent[root]?.entries).toMatchObject([
      { kind: 'child', id: S1, hasChildren: true },
    ])

    api.onSubagentList = () => Promise.resolve(ok({
      entries: [{
        kind: 'child', id: S1, mode: 'continuable', label: 'parent',
        activity: 'inactive', hasChildren: false,
      }] as never[],
      parentAvailable: true,
    }))
    await manager.refreshSubagents(root)
    expect(manager.getListSnapshot().subagentsByParent[root]?.entries).toMatchObject([
      { kind: 'child', id: S1, hasChildren: false },
    ])
  })

  it('replays status frames over an older in-flight catalog response', async () => {
    const api = new FakeApiClient()
    const root = 'fk-root' as SessionId
    const response = deferred<Awaited<ReturnType<FakeApiClient['onSubagentList']>>>()
    api.onSubagentList = () => response.promise
    const manager = new SessionManager(api)
    const refresh = manager.refreshSubagents(root)

    manager.handleHostEnvelope({
      rpcId: 'child-stopped' as never,
      payload: { type: 'host/session-status', sessionId: S1, running: false },
    })
    manager.handleHostEnvelope({
      rpcId: 'child-started' as never,
      payload: { type: 'host/session-status', sessionId: S2, running: true },
    })
    response.resolve(ok({
      entries: [
        {
          kind: 'child', id: S1, mode: 'continuable', label: 'stopped',
          activity: 'running', hasChildren: false,
        },
        {
          kind: 'child', id: S2, mode: 'continuable', label: 'started',
          activity: 'inactive', hasChildren: false,
        },
      ] as never[],
      parentAvailable: true,
    }))
    await refresh

    expect(manager.getListSnapshot().subagentsByParent[root]?.entries).toMatchObject([
      { kind: 'child', id: S1, activity: 'inactive' },
      { kind: 'child', id: S2, activity: 'running' },
    ])
  })

  it('marks a detached catalog child inactive without requiring a selected address', async () => {
    const api = new FakeApiClient()
    api.onSubagentList = () => Promise.resolve(ok({
      entries: [{
        kind: 'child', id: S2, mode: 'continuable', label: 'worker',
        activity: 'running', hasChildren: false,
      }] as never[],
      parentAvailable: true,
    }))
    const manager = new SessionManager(api)
    await manager.refreshSubagents(S1)

    manager.handleHostEnvelope({
      rpcId: 'child-detached' as never,
      payload: { type: 'host/session-removed', sessionId: S2 },
    })

    expect(manager.getListSnapshot().subagentsByParent[S1]?.entries).toMatchObject([
      { kind: 'child', id: S2, activity: 'inactive' },
    ])
  })

  it('coalesces overlapping catalog reads without scheduling a trailing pull', async () => {
    const api = new FakeApiClient()
    const root = 'fk-root' as SessionId
    const first = deferred<Awaited<ReturnType<FakeApiClient['onSubagentList']>>>()
    api.onSubagentList = () => first.promise
    const manager = new SessionManager(api)

    const refresh = manager.refreshSubagents(root)
    expect(manager.refreshSubagents(root)).toBe(refresh)
    api.onSubagentList = () => Promise.resolve(ok({ entries: [], parentAvailable: true }))
    first.resolve(ok({ entries: [], parentAvailable: true }))
    await refresh

    expect(api.callsOf('subagent.list')).toHaveLength(1)
  })

  it('runs one trailing catalog refresh for a membership change coalesced into an in-flight pull', async () => {
    vi.useFakeTimers()
    try {
      const api = new FakeApiClient()
      const root = 'fk-root' as SessionId
      const first = deferred<Awaited<ReturnType<FakeApiClient['onSubagentList']>>>()
      const second = deferred<Awaited<ReturnType<FakeApiClient['onSubagentList']>>>()
      api.onSubagentList = () => first.promise
      const manager = new SessionManager(api, root)
      const refresh = manager.refreshSubagents(root)

      // A membership frame arrives while the pull is in flight; the debounced
      // refresh it schedules fires 50ms later and is coalesced into the pull —
      // which was requested before the new child existed. The stale mark must
      // queue one trailing pull carrying the change.
      manager.handleHostEnvelope({
        rpcId: 'child-added' as never,
        payload: {
          type: 'host/session-added', sessionId: S2, parentSessionId: root, blank: false,
        },
      })
      await vi.advanceTimersByTimeAsync(50)
      api.onSubagentList = () => second.promise
      first.resolve(ok({
        entries: [{
          kind: 'child', id: S1, mode: 'continuable', label: 'older',
          activity: 'inactive', hasChildren: false,
        }] as never[],
        parentAvailable: true,
      }))
      await refresh
      // The trailing pull is already in flight (kicked synchronously in finally).
      second.resolve(ok({
        entries: [
          {
            kind: 'child', id: S1, mode: 'continuable', label: 'older',
            activity: 'inactive', hasChildren: false,
          },
          {
            kind: 'child', id: S2, mode: 'continuable', label: 'new child',
            activity: 'inactive', hasChildren: false,
          },
        ] as never[],
        parentAvailable: true,
      }))
      await second.promise

      expect(api.callsOf('subagent.list')).toHaveLength(2)
      expect(manager.getListSnapshot().subagentsByParent[root]?.entries).toMatchObject([
        { kind: 'child', id: S1, label: 'older' },
        { kind: 'child', id: S2, label: 'new child' },
      ])
    } finally {
      vi.useRealTimers()
    }
  })

  it('keeps removal invalidation across a stale success and failed trailing pull', async () => {
    const api = new FakeApiClient()
    const root = 'fk-root' as SessionId
    const child = () => ({
      kind: 'child' as const, id: S2, mode: 'continuable' as const, label: 'worker',
      activity: 'inactive' as const, hasChildren: false,
    })
    const first = deferred<Awaited<ReturnType<FakeApiClient['onSubagentList']>>>()
    api.onSubagentList = () => first.promise
    const manager = new SessionManager(api)
    const refresh = manager.refreshSubagents(root)
    first.resolve(ok({ entries: [child()] as never[], parentAvailable: true }))
    await refresh
    manager.selectSubagent({ parentSessionId: root, childSessionId: S2, mode: 'continuable' })

    // The removal lands while a second pull is in flight: the invalidation
    // must survive the pre-removal ok response, so one trailing pull runs.
    const mid = deferred<Awaited<ReturnType<FakeApiClient['onSubagentList']>>>()
    api.onSubagentList = () => mid.promise
    const midRefresh = manager.refreshSubagents(root)
    manager.handleHostEnvelope({
      rpcId: 'parent-removed-mid-pull' as never,
      payload: { type: 'host/session-removed', sessionId: root },
    })
    const trailing = deferred<Awaited<ReturnType<FakeApiClient['onSubagentList']>>>()
    api.onSubagentList = () => trailing.promise
    mid.resolve(ok({ entries: [child()] as never[], parentAvailable: true }))
    await midRefresh
    expect(manager.getListSnapshot().subagentsByParent[root]?.parentAvailable).toBe(false)
    expect(manager.get(S2).getSnapshot().subagent).toMatchObject({ parentAvailable: false })

    trailing.resolve(err({ code: 'internal', message: 'trailing pull failed', details: {} }))
    await vi.waitFor(() => {
      expect(manager.getListSnapshot().subagentsByParent[root]).toMatchObject({
        state: 'error',
        parentAvailable: false,
      })
    })

    const rootCalls = api.callsOf('subagent.list')
      .filter(call => (call as { parentSessionId: SessionId }).parentSessionId === root)
    expect(rootCalls).toHaveLength(3)
    expect(manager.getListSnapshot().subagentsByParent[root]?.parentAvailable).toBe(false)
    expect(manager.get(S2).getSnapshot().subagent).toMatchObject({ parentAvailable: false })
  })

  it('invalidates catalog availability when the owning parent is removed', async () => {
    const api = new FakeApiClient()
    const root = 'fk-root' as SessionId
    api.onSubagentList = () => Promise.resolve(ok({
      entries: [{
        kind: 'child', id: S2, mode: 'continuable', label: 'worker',
        activity: 'inactive', hasChildren: false,
      }] as never[],
      parentAvailable: true,
    }))
    const manager = new SessionManager(api)
    await manager.refreshSubagents(root)
    manager.selectSubagent({ parentSessionId: root, childSessionId: S2, mode: 'continuable' })
    expect(manager.get(S2).getSnapshot().subagent).toMatchObject({ parentAvailable: true })

    manager.handleHostEnvelope({
      rpcId: 'parent-removed' as never,
      payload: { type: 'host/session-removed', sessionId: root },
    })

    expect(manager.getListSnapshot().subagentsByParent[root]?.parentAvailable).toBe(false)
    expect(manager.get(S2).getSnapshot().subagent).toMatchObject({ parentAvailable: false })
  })
})

describe('remaining branches', () => {
  it('refreshList folds a transport throw into the error state', async () => {
    const api = new FakeApiClient()
    api.onList = () => Promise.reject(new Error('list wire down'))
    const manager = new SessionManager(api)
    await manager.refreshList()
    expect(manager.getListSnapshot()).toMatchObject({ state: 'error', error: { code: 'internal', message: 'list wire down' } })
  })

  it('refreshList pushes running bits down to already-instantiated sessions', async () => {
    const api = new FakeApiClient()
    const manager = new SessionManager(api)
    const session = manager.get(S1)
    api.onList = () => Promise.resolve(ok({ items: [summary(S1, { running: true })] as never[] }))
    await manager.refreshList()
    expect(session.getSnapshot().running).toBe(true)
  })

  it('create passes cwd and a preallocated id, folds transport throws, and deduplicates the echo', async () => {
    const api = new FakeApiClient()
    api.onCreate = () => Promise.resolve(ok({ sessionId: S1 }))
    const manager = new SessionManager(api)
    await manager.create({ cwd: '/tmp/w', sessionId: S1 })
    expect(api.callsOf('session.create')).toEqual([{ cwd: '/tmp/w', sessionId: S1 }])
    expect(manager.getListSnapshot().items[0]).toMatchObject({ sessionId: S1, cwd: '/tmp/w' })
    await manager.create({ cwd: '/tmp/w' }) // same id returned: no duplicate row
    expect(manager.getListSnapshot().items).toHaveLength(1)
    api.onCreate = () => Promise.reject(new Error('create wire down'))
    expect(await manager.create()).toMatchObject({ ok: false, error: { code: 'internal' } })
    // Business error passes through untouched.
    api.onCreate = () => Promise.resolve(err({ code: 'internal', message: 'no', details: {} }))
    expect(await manager.create()).toMatchObject({ ok: false })
  })

  it('publishes a real Ungrouped summary from workspace-attach-failed', async () => {
    const api = new FakeApiClient()
    api.onCreate = () => Promise.resolve(err({
      code: 'workspace-attach-failed',
      message: 'published but unattached',
      details: { sessionId: S1, workspaceId: 'w1' },
    } as never))
    const manager = new SessionManager(api)
    const result = await manager.create({ workspaceId: 'w1' as never, sessionId: S1 })
    expect(result).toMatchObject({ ok: false, error: { code: 'workspace-attach-failed' } })
    expect(manager.getListSnapshot().items).toEqual([expect.objectContaining({ sessionId: S1 })])
    expect(manager.getListSnapshot().items[0]).not.toHaveProperty('cwd')
  })

  it('reconciles a fork child published before workspace attachment fails', async () => {
    const api = new FakeApiClient()
    api.onFork = () => Promise.resolve(err({
      code: 'workspace-attach-failed',
      message: 'forked but unattached',
      details: { sessionId: S2, workspaceId: 'w1' },
    } as never))
    const manager = new SessionManager(api)
    const result = await manager.fork({ sessionId: S1 })
    expect(result).toMatchObject({ ok: false, error: { code: 'workspace-attach-failed' } })
    expect(manager.getListSnapshot().items).toEqual([expect.objectContaining({
      sessionId: S2,
      parentSessionId: S1,
      blank: false,
    })])
  })

  it('reconciles a preallocated id after an ordinary transport failure', async () => {
    const api = new FakeApiClient()
    api.onCreate = () => Promise.reject(new Error('response lost'))
    const manager = new SessionManager(api)
    const failed = await manager.create({ workspaceId: 'w1' as never, sessionId: S1 })
    expect(failed).toMatchObject({ ok: false, error: { message: 'response lost' } })
    expect(manager.getListSnapshot().items).toEqual([])

    manager.handleHostEnvelope({
      rpcId: 'published-later' as never,
      payload: { type: 'host/session-added', blank: true, sessionId: S1, cwd: '/w/one' },
    })
    expect(manager.getListSnapshot().items).toEqual([
      expect.objectContaining({ sessionId: S1, cwd: '/w/one' }),
    ])
    manager.handleHostEnvelope({
      rpcId: 'duplicate-frame' as never,
      payload: { type: 'host/session-added', blank: true, sessionId: S1, cwd: '/w/one' },
    })
    expect(manager.getListSnapshot().items).toHaveLength(1)
  })

  it('subscribe notifies on list changes and stops after unsubscribe', async () => {
    const api = new FakeApiClient()
    const manager = new SessionManager(api)
    let notified = 0
    const unsubscribe = manager.subscribe(() => { notified++ })
    await manager.refreshList()
    await new Promise(resolve => setTimeout(resolve, 0))
    expect(notified).toBeGreaterThan(0)
    const seen = notified
    unsubscribe()
    manager.handleHostEnvelope({ rpcId: 'h' as never, payload: { type: 'host/session-added', blank: true, sessionId: S1 } })
    await new Promise(resolve => setTimeout(resolve, 0))
    expect(notified).toBe(seen)
  })

  it('routes stream/error and unknown frames to the documented drops, and dispatches to instantiated sessions', () => {
    const api = new FakeApiClient()
    const manager = new SessionManager(api)
    manager.handleMuxEnvelope({ rpcId: 'e' as never, payload: { type: 'stream/error', error: { code: 'internal', message: 'x', details: {} } } })
    manager.handleHostEnvelope({ rpcId: 'e2' as never, payload: { type: 'stream/error', error: { code: 'internal', message: 'x', details: {} } } })
    manager.handleHostEnvelope({ rpcId: 'e3' as never, payload: { type: 'future/host-frame' } as never })
    const session = manager.get(S1)
    manager.handleMuxEnvelope({ rpcId: 'q1' as never, payload: { type: 'question/requested', sessionId: S1, questions: [] } })
    expect(session.getSnapshot().pending).toMatchObject([{ kind: 'question' }])
    // status flip for an unknown session only touches summaries (no crash).
    manager.handleHostEnvelope({ rpcId: 'h9' as never, payload: { type: 'host/session-status', sessionId: S2, running: true } })
    manager.handleHostEnvelope({ rpcId: 'ha' as never, payload: { type: 'host/agent-error', sessionId: S2, message: '无实例' } })
  })

  it('keeps list-entry identity for unchanged rows across an unrelated list change', async () => {
    const api = new FakeApiClient()
    api.onList = () => Promise.resolve(ok({ items: [summary(S1), summary(S2, { updatedAt: 200 })] as never[] }))
    const manager = new SessionManager(api)
    await manager.refreshList()
    const before = manager.getListSnapshot()
    manager.handleHostEnvelope({ rpcId: 'h' as never, payload: { type: 'host/session-status', sessionId: S2, running: true } })
    const after = manager.getListSnapshot()
    expect(after.items).not.toBe(before.items)
    const beforeS1 = before.items.find(e => e.sessionId === S1)
    const afterS1 = after.items.find(e => e.sessionId === S1)
    expect(afterS1).toBe(beforeS1) // untouched entry keeps identity (entryCache)
    // Same-order same-entries snapshot reuses the items array.
    manager.handleHostEnvelope({ rpcId: 'h2' as never, payload: { type: 'host/agent-error', sessionId: S1, message: 'x' } })
    expect(manager.getListSnapshot().items).toBe(after.items)
  })

  it('carries parentSessionId from host/session-added into the lineage row', () => {
    const api = new FakeApiClient()
    const manager = new SessionManager(api)
    manager.handleHostEnvelope({ rpcId: 'h1' as never, payload: { type: 'host/session-added', blank: true, sessionId: S1 } })
    manager.handleHostEnvelope({
      rpcId: 'h2' as never,
      payload: {
        type: 'host/session-added', blank: true, sessionId: S2,
        parentSessionId: S1, origin: 'subagent',
      },
    })
    const items = manager.getListSnapshot().items
    expect(items.find(e => e.sessionId === S2)).toMatchObject({
      parentSessionId: S1, origin: 'subagent', depth: 1,
    })
  })
})

describe('connected generation', () => {
  it('refreshes the list and resyncs only opened instances', async () => {
    const api = new FakeApiClient()
    api.onHistory = () => Promise.resolve(ok({
      events: entries(plainTurn(0, 0, 'a', 'b')) as never[],
      hasMore: false,
      modelTarget: { provider: 'deepseek-official', model: 'deepseek-chat' },
    }))
    const manager = new SessionManager(api)
    const openedSession = manager.get(S1)
    await openedSession.open()
    manager.get(S2) // instantiated but never opened
    const historyCallsBefore = api.callsOf('session.history').length
    manager.handleConnected()
    await vi.waitFor(() => {
      expect(api.callsOf('session.list').length).toBe(1)
      // Only the opened instance repulls history; the cold one stays silent.
      expect(api.callsOf('session.history').length).toBe(historyCallsBefore + 1)
    })
  })

  it('reloads the durable parent address for a restored child selection', async () => {
    const api = new FakeApiClient()
    const address = {
      parentSessionId: S1, childSessionId: S2, mode: 'continuable' as const,
    }
    const manager = new SessionManager(api, S2, address)

    manager.handleConnected()

    await vi.waitFor(() => {
      expect(api.callsOf('subagent.list')).toContainEqual({ parentSessionId: S1 })
    })
    expect(manager.getListSnapshot().currentAddress).toEqual(address)
  })
})

describe('pending-interaction list status', () => {
  it('tracks approval requests through replay and resolution without instantiation', () => {
    const manager = new SessionManager(new FakeApiClient())
    manager.handleHostEnvelope({ rpcId: 'h1' as never, payload: { type: 'host/session-added', sessionId: S1, blank: false } })
    expect(manager.getListSnapshot().items[0]?.pendingInteraction).toBeUndefined()
    manager.handleMuxEnvelope({ rpcId: 'ra' as never, payload: { type: 'approval/requested', sessionId: S1, approvalId: 'ap1' as never, toolName: 'rm' } })
    expect(manager.getListSnapshot().items[0]?.pendingInteraction).toBe('approval')
    // Mux-open replay of the same question (same approvalId) is idempotent.
    manager.handleMuxEnvelope({ rpcId: 'ra' as never, payload: { type: 'approval/requested', sessionId: S1, approvalId: 'ap1' as never, toolName: 'rm' } })
    expect(manager.getListSnapshot().items[0]?.pendingInteraction).toBe('approval')
    manager.handleMuxEnvelope({ rpcId: 'rx' as never, payload: { type: 'approval/resolved', sessionId: S1, approvalId: 'ap1' as never, outcome: 'allowed-once' as never } })
    expect(manager.getListSnapshot().items[0]?.pendingInteraction).toBeUndefined()
  })

  it('classifies ordinary questions and renderable plan reviews, then clears by question rpcId', () => {
    const manager = new SessionManager(new FakeApiClient())
    manager.handleHostEnvelope({ rpcId: 'h1' as never, payload: { type: 'host/session-added', sessionId: S1, blank: false } })
    manager.handleMuxEnvelope({
      rpcId: 'q1' as never,
      payload: { type: 'question/requested', sessionId: S1, questions: [{ id: 'name', question: 'Name?' }] },
    })
    expect(manager.getListSnapshot().items[0]?.pendingInteraction).toBe('question')
    manager.handleMuxEnvelope({ rpcId: 'qx' as never, payload: { type: 'question/resolved', sessionId: S1, questionRpcId: 'q1' as never, outcome: 'answered' } })
    expect(manager.getListSnapshot().items[0]?.pendingInteraction).toBeUndefined()

    manager.handleMuxEnvelope({
      rpcId: 'q2' as never,
      payload: {
        type: 'question/requested',
        sessionId: S1,
        questions: [{
          id: 'plan', question: 'Approve?', detail: '# Plan',
          options: [{ label: 'Approve' }, { label: 'Refuse' }],
          intent: { kind: 'plan-review', approve: 'Approve' },
        }],
      },
    })
    expect(manager.getListSnapshot().items[0]?.pendingInteraction).toBe('plan-review')
    manager.handleMuxEnvelope({ rpcId: 'qy' as never, payload: { type: 'question/resolved', sessionId: S1, questionRpcId: 'q2' as never, outcome: 'cancelled' } })
    expect(manager.getListSnapshot().items[0]?.pendingInteraction).toBeUndefined()
  })

  it.each([
    ['missing detail', {}],
    ['multi-select', { detail: '# Plan', multiSelect: true }],
    ['more than two options', { detail: '# Plan', options: [{ label: 'Approve' }, { label: 'Refuse' }, { label: 'Revise' }] }],
    ['missing approve option', { detail: '# Plan', options: [{ label: 'Refuse' }] }],
  ])('keeps an unrenderable %s plan intent on the ordinary question flow', (_name, over) => {
    const manager = new SessionManager(new FakeApiClient())
    manager.handleHostEnvelope({ rpcId: 'h1' as never, payload: { type: 'host/session-added', sessionId: S1, blank: false } })
    manager.handleMuxEnvelope({
      rpcId: 'q-plan' as never,
      payload: {
        type: 'question/requested', sessionId: S1,
        questions: [{
          id: 'plan', question: 'Approve?', options: [{ label: 'Approve' }],
          intent: { kind: 'plan-review', approve: 'Approve' },
          ...over,
        }],
      },
    })
    expect(manager.getListSnapshot().items[0]?.pendingInteraction).toBe('question')
  })

  it('the first question outranks sibling approvals and resolving it reveals the remaining wait', () => {
    const manager = new SessionManager(new FakeApiClient())
    manager.handleHostEnvelope({ rpcId: 'h1' as never, payload: { type: 'host/session-added', sessionId: S1, blank: false } })
    manager.handleMuxEnvelope({ rpcId: 'r1' as never, payload: { type: 'approval/requested', sessionId: S1, approvalId: 'a1' as never, toolName: 'rm' } })
    manager.handleMuxEnvelope({
      rpcId: 'q1' as never,
      payload: { type: 'question/requested', sessionId: S1, questions: [{ id: 'name', question: 'Name?' }] },
    })
    expect(manager.getListSnapshot().items[0]?.pendingInteraction).toBe('question')
    manager.handleMuxEnvelope({ rpcId: 'qy' as never, payload: { type: 'question/resolved', sessionId: S1, questionRpcId: 'q1' as never, outcome: 'answered' } })
    expect(manager.getListSnapshot().items[0]?.pendingInteraction).toBe('approval')
    manager.handleMuxEnvelope({ rpcId: 'rx' as never, payload: { type: 'approval/resolved', sessionId: S1, approvalId: 'a1' as never, outcome: 'rejected' as never } })
    expect(manager.getListSnapshot().items[0]?.pendingInteraction).toBeUndefined()

    manager.handleMuxEnvelope({ rpcId: 'r2' as never, payload: { type: 'approval/requested', sessionId: S1, approvalId: 'a2' as never, toolName: 'rm' } })
    manager.handleHostEnvelope({ rpcId: 'h2' as never, payload: { type: 'host/session-removed', sessionId: S1 } })
    expect(manager.getListSnapshot().items).toHaveLength(0)
  })

  it('drops stale status at generation death before replay re-adds live interactions', () => {
    const manager = new SessionManager(new FakeApiClient())
    manager.handleHostEnvelope({ rpcId: 'h1' as never, payload: { type: 'host/session-added', sessionId: S1, blank: false } })
    manager.handleMuxEnvelope({ rpcId: 'ra' as never, payload: { type: 'approval/requested', sessionId: S1, approvalId: 'ap1' as never, toolName: 'rm' } })
    expect(manager.getListSnapshot().items[0]?.pendingInteraction).toBe('approval')
    // Generation death clears (resolved-while-disconnected questions send no frame)…
    manager.handleDisconnected()
    expect(manager.getListSnapshot().items[0]?.pendingInteraction).toBeUndefined()
    // …and a replayed frame arriving before onConnected (stream open precedes
    // the readiness handshake) survives the later handleConnected untouched.
    manager.handleMuxEnvelope({ rpcId: 'ra' as never, payload: { type: 'approval/requested', sessionId: S1, approvalId: 'ap1' as never, toolName: 'rm' } })
    manager.handleConnected()
    expect(manager.getListSnapshot().items[0]?.pendingInteraction).toBe('approval')
  })

  it('generation death drops buffered answerable frames (a dead generation cannot be answered)', () => {
    const manager = new SessionManager(new FakeApiClient())
    manager.handleHostEnvelope({ rpcId: 'h1' as never, payload: { type: 'host/session-added', sessionId: S1, blank: false } })
    // Buffered pre-instantiation: an approval pair and a queued row.
    manager.handleMuxEnvelope({ rpcId: 'ra' as never, payload: { type: 'approval/requested', sessionId: S1, approvalId: 'ap1' as never, toolName: 'rm' } })
    manager.handleMuxEnvelope({ rpcId: 'q1' as never, payload: { type: 'question/requested', sessionId: S1, questions: [] } })
    manager.handleDisconnected()
    // Instantiate after the death sweep: no zombie interaction replays (the
    // pendingBuffers held only dead-generation rpcIds), so the session mints
    // no pending waits.
    const session = manager.get(S1)
    expect(session.getSnapshot().pending).toEqual([])
  })
})