orca/src/relay/fs-handler.test.ts

import { describe, expect, it, vi, beforeEach, afterEach } from 'vitest'
import { FsHandler } from './fs-handler'
import { MAX_TEXT_FILE_SIZE } from './fs-handler-utils'
import { RelayContext } from './context'
import type { RelayDispatcher } from './dispatcher'
import * as fs from 'node:fs/promises'
import * as path from 'node:path'
import { mkdtempSync, writeFileSync, mkdirSync, symlinkSync } from 'node:fs'
import { tmpdir } from 'node:os'
import { subscribeWithInProcessWatcher } from '../main/ipc/parcel-watcher-in-process-fallback'

const { mockSubscribe } = vi.hoisted(() => ({
  mockSubscribe: vi.fn()
}))

vi.mock('@parcel/watcher', () => ({
  subscribe: mockSubscribe
}))

function createMockDispatcher() {
  const requestHandlers = new Map<
    string,
    (
      params: Record<string, unknown>,
      context?: { clientId: number; isStale: () => boolean }
    ) => Promise<unknown>
  >()
  const notificationHandlers = new Map<
    string,
    (
      params: Record<string, unknown>,
      context?: { clientId: number; isStale: () => boolean }
    ) => void
  >()
  const detachListeners = new Set<(clientId: number) => void>()
  const notifications: { method: string; params?: Record<string, unknown> }[] = []

  return {
    onRequest: vi.fn(
      (
        method: string,
        handler: (
          params: Record<string, unknown>,
          context?: { clientId: number; isStale: () => boolean }
        ) => Promise<unknown>
      ) => {
        requestHandlers.set(method, handler)
      }
    ),
    onNotification: vi.fn(
      (
        method: string,
        handler: (
          params: Record<string, unknown>,
          context?: { clientId: number; isStale: () => boolean }
        ) => void
      ) => {
        notificationHandlers.set(method, handler)
      }
    ),
    notify: vi.fn((method: string, params?: Record<string, unknown>) => {
      notifications.push({ method, params })
    }),
    notifyClient: vi.fn(),
    onClientDetached: vi.fn((listener: (clientId: number) => void) => {
      detachListeners.add(listener)
      return () => detachListeners.delete(listener)
    }),
    _requestHandlers: requestHandlers,
    _notificationHandlers: notificationHandlers,
    _notifications: notifications,
    async callRequest(
      method: string,
      params: Record<string, unknown> = {},
      context?: { clientId?: number; isStale: () => boolean }
    ) {
      const handler = requestHandlers.get(method)
      if (!handler) {
        throw new Error(`No handler for ${method}`)
      }
      return handler(params, {
        clientId: context?.clientId ?? 1,
        isStale: context?.isStale ?? (() => false)
      })
    },
    callNotification(
      method: string,
      params: Record<string, unknown> = {},
      context?: { clientId: number; isStale: () => boolean }
    ) {
      const handler = notificationHandlers.get(method)
      if (!handler) {
        throw new Error(`No handler for ${method}`)
      }
      handler(params, context ?? { clientId: 1, isStale: () => false })
    },
    detachClient(clientId: number) {
      for (const listener of detachListeners) {
        listener(clientId)
      }
    }
  }
}

function statIdentity(stats: {
  dev?: number
  ino?: number
  nlink?: number
  size?: number
  mtimeMs?: number
}) {
  return `${stats.dev}:${stats.ino}:${stats.nlink ?? 'unknown'}:${stats.size}:${stats.mtimeMs}`
}

describe('FsHandler', () => {
  let dispatcher: ReturnType<typeof createMockDispatcher>
  let handler: FsHandler
  let tmpDir: string

  beforeEach(() => {
    mockSubscribe.mockReset()
    mockSubscribe.mockResolvedValue({ unsubscribe: vi.fn() })
    tmpDir = mkdtempSync(path.join(tmpdir(), 'relay-fs-'))
    dispatcher = createMockDispatcher()
    const ctx = new RelayContext()
    handler = new FsHandler(dispatcher as unknown as RelayDispatcher, ctx, {
      dispose: vi.fn(),
      forgetRoot: vi.fn(),
      subscribe: subscribeWithInProcessWatcher
    })
  })

  afterEach(async () => {
    handler.dispose()
    await fs.rm(tmpDir, { recursive: true, force: true })
  })

  it('registers all expected handlers', () => {
    const methods = Array.from(dispatcher._requestHandlers.keys())
    expect(methods).toContain('fs.readDir')
    expect(methods).toContain('fs.readFile')
    expect(methods).toContain('fs.tempDir')
    expect(methods).toContain('fs.writeFile')
    expect(methods).toContain('fs.stat')
    expect(methods).toContain('fs.deletePath')
    expect(methods).toContain('fs.createFile')
    expect(methods).toContain('fs.createDir')
    expect(methods).toContain('fs.createDirNoClobber')
    expect(methods).toContain('fs.rename')
    expect(methods).toContain('fs.renameNoClobber')
    expect(methods).toContain('fs.copy')
    expect(methods).toContain('fs.realpath')
    expect(methods).toContain('fs.search')
    expect(methods).toContain('fs.listFiles')
    expect(methods).toContain('fs.workspaceSpaceScan')
    expect(methods).toContain('fs.watch')
    expect(methods).toContain('fs.unwatchAndWait')

    const notifMethods = Array.from(dispatcher._notificationHandlers.keys())
    expect(notifMethods).toContain('fs.unwatch')
  })

  it('tempDir returns the relay host temp directory', async () => {
    await expect(dispatcher.callRequest('fs.tempDir')).resolves.toBe(tmpdir())
  })

  it('readDir returns entries directories-first in natural name order', async () => {
    mkdirSync(path.join(tmpDir, 'subdir'))
    for (const name of ['file.txt', '100 - b.txt', '99 - a.txt', '9 - c.txt']) {
      writeFileSync(path.join(tmpDir, name), 'x')
    }

    const result = (await dispatcher.callRequest('fs.readDir', { dirPath: tmpDir })) as {
      name: string
      isDirectory: boolean
    }[]
    expect(result[0]).toMatchObject({ name: 'subdir', isDirectory: true })
    expect(result.slice(1).map((e) => e.name)).toEqual([
      '9 - c.txt',
      '99 - a.txt',
      '100 - b.txt',
      'file.txt'
    ])
  })

  it('readDir reports symlinked directories as directories', async () => {
    const targetDir = path.join(tmpDir, 'external-models')
    const linkPath = path.join(tmpDir, 'Model')
    mkdirSync(targetDir)
    symlinkSync(targetDir, linkPath, process.platform === 'win32' ? 'junction' : 'dir')

    const result = (await dispatcher.callRequest('fs.readDir', { dirPath: tmpDir })) as {
      name: string
      isDirectory: boolean
      isSymlink: boolean
    }[]

    expect(result.find((e) => e.name === 'Model')).toEqual({
      name: 'Model',
      isDirectory: true,
      isSymlink: true
    })
  })

  it('readFile returns text content for text files', async () => {
    const filePath = path.join(tmpDir, 'test.txt')
    writeFileSync(filePath, 'hello world')

    const result = (await dispatcher.callRequest('fs.readFile', { filePath })) as {
      content: string
      isBinary: boolean
    }
    expect(result.content).toBe('hello world')
    expect(result.isBinary).toBe(false)
  })

  it('readFile returns text files larger than the old 5MB guard', async () => {
    const filePath = path.join(tmpDir, 'large.json')
    const content = 'a'.repeat(6 * 1024 * 1024)
    writeFileSync(filePath, content)

    const result = (await dispatcher.callRequest('fs.readFile', { filePath })) as {
      content: string
      isBinary: boolean
    }
    expect(result.content).toBe(content)
    expect(result.isBinary).toBe(false)
  })

  it('readFile returns binary marker for large unknown binary files', async () => {
    const filePath = path.join(tmpDir, 'archive.bin')
    const content = Buffer.alloc(6 * 1024 * 1024, 0x61)
    content[0] = 0x00
    writeFileSync(filePath, content)

    const result = (await dispatcher.callRequest('fs.readFile', { filePath })) as {
      content: string
      isBinary: boolean
    }
    expect(result.content).toBe('')
    expect(result.isBinary).toBe(true)
  })

  it('readFile returns base64 for image files', async () => {
    const filePath = path.join(tmpDir, 'test.png')
    writeFileSync(filePath, Buffer.from([0x89, 0x50, 0x4e, 0x47]))

    const result = (await dispatcher.callRequest('fs.readFile', { filePath })) as {
      content: string
      isBinary: boolean
      isImage: boolean
      mimeType: string
    }
    expect(result.isBinary).toBe(true)
    expect(result.isImage).toBe(true)
    expect(result.mimeType).toBe('image/png')
    expect(result.content).toBeTruthy()
  })

  it('readFile throws for files exceeding size limit', async () => {
    const filePath = path.join(tmpDir, 'huge.txt')
    writeFileSync(filePath, Buffer.alloc(11 * 1024 * 1024, 'a'))

    await expect(dispatcher.callRequest('fs.readFile', { filePath })).rejects.toThrow(
      'File too large'
    )
  })

  it('writeFile creates/overwrites file content', async () => {
    const filePath = path.join(tmpDir, 'write-test.txt')
    await dispatcher.callRequest('fs.writeFile', { filePath, content: 'new content' })

    const content = await fs.readFile(filePath, 'utf-8')
    expect(content).toBe('new content')
  })

  it('readTerminalArtifact reads through a verified artifact handle', async () => {
    const filePath = path.join(tmpDir, 'artifact-read.json')
    writeFileSync(filePath, '{"ok":true}')
    const stats = await fs.stat(filePath)

    const result = (await dispatcher.callRequest('fs.readTerminalArtifact', {
      filePath,
      expectedRealPath: await fs.realpath(filePath),
      expectedStatIdentity: statIdentity(stats),
      maxBytes: 512 * 1024
    })) as { content: string; isBinary: boolean }

    expect(result).toEqual({ content: '{"ok":true}', isBinary: false })
  })

  it('readTerminalArtifact treats SVG artifacts as editable text', async () => {
    const filePath = path.join(tmpDir, 'artifact.svg')
    writeFileSync(filePath, '<svg><text>ok</text></svg>')
    const stats = await fs.stat(filePath)

    const result = (await dispatcher.callRequest('fs.readTerminalArtifact', {
      filePath,
      expectedRealPath: await fs.realpath(filePath),
      expectedStatIdentity: statIdentity(stats),
      maxBytes: 512 * 1024
    })) as { content: string; isBinary: boolean; isImage?: boolean }

    expect(result).toEqual({ content: '<svg><text>ok</text></svg>', isBinary: false })
  })

  it('readTerminalArtifact rejects content beyond the requested byte limit', async () => {
    const filePath = path.join(tmpDir, 'artifact-read-too-large.txt')
    writeFileSync(filePath, 'abcdef')

    await expect(
      dispatcher.callRequest('fs.readTerminalArtifact', {
        filePath,
        expectedRealPath: await fs.realpath(filePath),
        maxBytes: 5
      })
    ).rejects.toThrow('file_too_large')
  })

  it('writeTerminalArtifact writes through a verified artifact handle', async () => {
    const filePath = path.join(tmpDir, 'artifact-write.json')
    writeFileSync(filePath, '{"ok":true}')
    const stats = await fs.stat(filePath)

    const result = (await dispatcher.callRequest('fs.writeTerminalArtifact', {
      filePath,
      content: '{"ok":false}',
      expectedRealPath: await fs.realpath(filePath),
      expectedStatIdentity: statIdentity(stats),
      maxBytes: 512 * 1024
    })) as { stat: { type: string; size: number } }

    await expect(fs.readFile(filePath, 'utf-8')).resolves.toBe('{"ok":false}')
    expect(result.stat).toMatchObject({ type: 'file', size: 12 })
  })

  it.skipIf(process.platform === 'win32')(
    'writeTerminalArtifact preserves executable mode across the atomic rename',
    async () => {
      const filePath = path.join(tmpDir, 'artifact-executable.sh')
      writeFileSync(filePath, '#!/bin/sh\necho ok\n')
      await fs.chmod(filePath, 0o755)
      const stats = await fs.stat(filePath)

      await dispatcher.callRequest('fs.writeTerminalArtifact', {
        filePath,
        content: '#!/bin/sh\necho changed\n',
        expectedRealPath: await fs.realpath(filePath),
        expectedStatIdentity: statIdentity(stats),
        maxBytes: 512 * 1024
      })

      expect((await fs.stat(filePath)).mode & 0o777).toBe(0o755)
    }
  )

  it('writeTerminalArtifact rejects oversized existing content before writing', async () => {
    const filePath = path.join(tmpDir, 'artifact-write-too-large.txt')
    writeFileSync(filePath, 'abcdef')

    await expect(
      dispatcher.callRequest('fs.writeTerminalArtifact', {
        filePath,
        content: 'ok',
        expectedRealPath: await fs.realpath(filePath),
        maxBytes: 5
      })
    ).rejects.toThrow('file_too_large')
    await expect(fs.readFile(filePath, 'utf-8')).resolves.toBe('abcdef')
  })

  it('writeTerminalArtifact clamps client-supplied maxBytes to the text-file cap', async () => {
    const filePath = path.join(tmpDir, 'artifact-write-clamp.txt')
    writeFileSync(filePath, 'abcdef')

    await expect(
      dispatcher.callRequest('fs.writeTerminalArtifact', {
        filePath,
        content: 'a'.repeat(MAX_TEXT_FILE_SIZE + 1),
        expectedRealPath: await fs.realpath(filePath),
        maxBytes: Number.MAX_SAFE_INTEGER
      })
    ).rejects.toThrow('file_too_large')
    await expect(fs.readFile(filePath, 'utf-8')).resolves.toBe('abcdef')
  })

  it('writeTerminalArtifact rejects a retargeted symlink before writing outside temp', async () => {
    const filePath = path.join(tmpDir, 'artifact-link.json')
    const outsidePath = path.join(tmpDir, 'outside.json')
    writeFileSync(filePath, '{"ok":true}')
    writeFileSync(outsidePath, '{"secret":true}')
    const stats = await fs.stat(filePath)
    const expectedRealPath = await fs.realpath(filePath)
    await fs.rm(filePath)
    symlinkSync(outsidePath, filePath)

    await expect(
      dispatcher.callRequest('fs.writeTerminalArtifact', {
        filePath,
        content: '{"ok":false}',
        expectedRealPath,
        expectedStatIdentity: statIdentity(stats),
        maxBytes: 512 * 1024
      })
    ).rejects.toThrow('terminal_file_grant_stale')
    await expect(fs.readFile(outsidePath, 'utf-8')).resolves.toBe('{"secret":true}')
  })

  it('writeTerminalArtifact rejects hard-linked files before writing', async () => {
    const outsidePath = path.join(tmpDir, 'outside-hardlink.json')
    const filePath = path.join(tmpDir, 'artifact-hardlink.json')
    writeFileSync(outsidePath, '{"secret":true}')
    await fs.link(outsidePath, filePath)
    const stats = await fs.stat(filePath)

    await expect(
      dispatcher.callRequest('fs.writeTerminalArtifact', {
        filePath,
        content: '{"ok":false}',
        expectedRealPath: await fs.realpath(filePath),
        expectedStatIdentity: statIdentity(stats),
        maxBytes: 512 * 1024
      })
    ).rejects.toThrow('terminal_file_grant_stale')
    await expect(fs.readFile(outsidePath, 'utf-8')).resolves.toBe('{"secret":true}')
  })

  it('stat returns file metadata', async () => {
    const filePath = path.join(tmpDir, 'stat-test.txt')
    writeFileSync(filePath, 'test')

    const result = (await dispatcher.callRequest('fs.stat', { filePath })) as {
      size: number
      type: string
      mtime: number
    }
    expect(result.type).toBe('file')
    expect(result.size).toBe(4)
    expect(typeof result.mtime).toBe('number')
  })

  it('stat returns directory type for directories', async () => {
    const result = (await dispatcher.callRequest('fs.stat', { filePath: tmpDir })) as {
      type: string
    }
    expect(result.type).toBe('directory')
  })

  it('stat returns directory type for symlinked directories', async () => {
    const targetDir = path.join(tmpDir, 'external-models')
    const linkPath = path.join(tmpDir, 'Model')
    mkdirSync(targetDir)
    symlinkSync(targetDir, linkPath, process.platform === 'win32' ? 'junction' : 'dir')

    const result = (await dispatcher.callRequest('fs.stat', { filePath: linkPath })) as {
      type: string
    }

    expect(result.type).toBe('directory')
  })

  it('lstat returns symlink type without following links', async () => {
    const targetFile = path.join(tmpDir, 'target.txt')
    const linkPath = path.join(tmpDir, 'link.txt')
    writeFileSync(targetFile, 'target')
    symlinkSync(targetFile, linkPath)

    const result = (await dispatcher.callRequest('fs.lstat', { filePath: linkPath })) as {
      type: string
    }

    expect(result.type).toBe('symlink')
  })

  it('workspaceSpaceScan returns bounded top-level size details', async () => {
    mkdirSync(path.join(tmpDir, 'node_modules'))
    writeFileSync(path.join(tmpDir, 'node_modules', 'pkg.js'), Buffer.alloc(512))
    writeFileSync(path.join(tmpDir, 'file.log'), Buffer.alloc(128))

    const result = (await dispatcher.callRequest(
      'fs.workspaceSpaceScan',
      { rootPath: tmpDir },
      { isStale: () => false }
    )) as {
      sizeBytes: number
      topLevelItems: { name: string; sizeBytes: number }[]
    }

    expect(result.sizeBytes).toBeGreaterThanOrEqual(640)
    expect(result.topLevelItems.map((item) => item.name)).toContain('node_modules')
    expect(result.topLevelItems.map((item) => item.name)).toContain('file.log')
  })

  it('deletePath removes files', async () => {
    const filePath = path.join(tmpDir, 'to-delete.txt')
    writeFileSync(filePath, 'bye')

    await dispatcher.callRequest('fs.deletePath', { targetPath: filePath })
    await expect(fs.access(filePath)).rejects.toThrow()
  })

  it('holds the relay watcher fence through recursive directory deletion', async () => {
    const directoryPath = path.join(tmpDir, 'watched-orphan')
    mkdirSync(directoryPath)
    const unsubscribe = vi.fn()
    mockSubscribe.mockResolvedValue({ unsubscribe })
    await dispatcher.callRequest(
      'fs.watch',
      { rootPath: directoryPath, watchId: 77 },
      { clientId: 3, isStale: () => false }
    )

    await dispatcher.callRequest('fs.deletePath', { targetPath: directoryPath, recursive: true })

    expect(unsubscribe).toHaveBeenCalledTimes(1)
    expect(dispatcher.notifyClient).toHaveBeenCalledWith(3, 'fs.watchFailed', {
      rootPath: directoryPath,
      watchId: 77,
      message: 'Remote worktree is being removed'
    })
    await expect(fs.access(directoryPath)).rejects.toThrow()
  })

  it('createFile creates an empty file with parent dirs', async () => {
    const filePath = path.join(tmpDir, 'deep', 'nested', 'file.txt')
    await dispatcher.callRequest('fs.createFile', { filePath })

    const content = await fs.readFile(filePath, 'utf-8')
    expect(content).toBe('')
  })

  it('createDir creates directories recursively', async () => {
    const dirPath = path.join(tmpDir, 'a', 'b', 'c')
    await dispatcher.callRequest('fs.createDir', { dirPath })

    const stats = await fs.stat(dirPath)
    expect(stats.isDirectory()).toBe(true)
  })

  it('createDirNoClobber fails when the directory already exists', async () => {
    const dirPath = path.join(tmpDir, 'existing')
    mkdirSync(dirPath)

    await expect(dispatcher.callRequest('fs.createDirNoClobber', { dirPath })).rejects.toThrow()
  })

  it('rename moves files', async () => {
    const oldPath = path.join(tmpDir, 'old.txt')
    const newPath = path.join(tmpDir, 'new.txt')
    writeFileSync(oldPath, 'content')

    await dispatcher.callRequest('fs.rename', { oldPath, newPath })

    await expect(fs.access(oldPath)).rejects.toThrow()
    const content = await fs.readFile(newPath, 'utf-8')
    expect(content).toBe('content')
  })

  it('rename preserves raw fs.rename overwrite semantics', async () => {
    const oldPath = path.join(tmpDir, 'old.txt')
    const newPath = path.join(tmpDir, 'existing.txt')
    writeFileSync(oldPath, 'new')
    writeFileSync(newPath, 'keep')

    await dispatcher.callRequest('fs.rename', { oldPath, newPath })

    expect(await fs.readFile(newPath, 'utf-8')).toBe('new')
    await expect(fs.access(oldPath)).rejects.toThrow()
  })

  it('renameNoClobber moves files when destination is available', async () => {
    const oldPath = path.join(tmpDir, 'old.txt')
    const newPath = path.join(tmpDir, 'new.txt')
    writeFileSync(oldPath, 'content')

    await dispatcher.callRequest('fs.renameNoClobber', { oldPath, newPath })

    await expect(fs.access(oldPath)).rejects.toThrow()
    expect(await fs.readFile(newPath, 'utf-8')).toBe('content')
  })

  it('renameNoClobber does not overwrite an existing destination', async () => {
    const oldPath = path.join(tmpDir, 'old.txt')
    const newPath = path.join(tmpDir, 'existing.txt')
    writeFileSync(oldPath, 'new')
    writeFileSync(newPath, 'keep')

    await expect(
      dispatcher.callRequest('fs.renameNoClobber', { oldPath, newPath })
    ).rejects.toThrow()

    expect(await fs.readFile(newPath, 'utf-8')).toBe('keep')
    expect(await fs.readFile(oldPath, 'utf-8')).toBe('new')
  })

  it('copy duplicates files', async () => {
    const src = path.join(tmpDir, 'src.txt')
    const dst = path.join(tmpDir, 'dst.txt')
    writeFileSync(src, 'original')

    await dispatcher.callRequest('fs.copy', { source: src, destination: dst })

    const content = await fs.readFile(dst, 'utf-8')
    expect(content).toBe('original')
  })

  it('copy does not overwrite an existing destination', async () => {
    const src = path.join(tmpDir, 'src.txt')
    const dst = path.join(tmpDir, 'dst.txt')
    writeFileSync(src, 'original')
    writeFileSync(dst, 'existing')

    await expect(
      dispatcher.callRequest('fs.copy', { source: src, destination: dst })
    ).rejects.toThrow('EEXIST')

    const content = await fs.readFile(dst, 'utf-8')
    expect(content).toBe('existing')
  })

  it('realpath resolves symlinks', async () => {
    const realFile = path.join(tmpDir, 'real.txt')
    const linkPath = path.join(tmpDir, 'link.txt')
    writeFileSync(realFile, 'real')
    symlinkSync(realFile, linkPath)

    const result = (await dispatcher.callRequest('fs.realpath', { filePath: linkPath })) as string
    // On macOS, /var is a symlink to /private/var, so resolve both to compare
    expect(result).toBe(await fs.realpath(realFile))
  })

  it('does not let stale pending watch remove newer replacement watch', async () => {
    const firstUnsubscribe = vi.fn()
    const secondUnsubscribe = vi.fn()
    let resolveFirst!: () => void
    mockSubscribe
      .mockReturnValueOnce(
        new Promise((resolve) => {
          resolveFirst = () => resolve({ unsubscribe: firstUnsubscribe })
        })
      )
      .mockResolvedValueOnce({ unsubscribe: secondUnsubscribe })

    const firstWatch = dispatcher.callRequest(
      'fs.watch',
      { rootPath: tmpDir },
      { isStale: () => true }
    )
    while (mockSubscribe.mock.calls.length === 0) {
      await Promise.resolve()
    }
    await dispatcher.callRequest('fs.watch', { rootPath: tmpDir }, { isStale: () => false })
    resolveFirst()
    await firstWatch

    expect(firstUnsubscribe).toHaveBeenCalled()
    expect(secondUnsubscribe).not.toHaveBeenCalled()
    dispatcher.callNotification('fs.unwatch', { rootPath: tmpDir })
    expect(secondUnsubscribe).toHaveBeenCalled()
  })

  it('unsubscribes an active stale watch before replacing it', async () => {
    const firstUnsubscribe = vi.fn()
    const secondUnsubscribe = vi.fn()
    mockSubscribe
      .mockResolvedValueOnce({ unsubscribe: firstUnsubscribe })
      .mockResolvedValueOnce({ unsubscribe: secondUnsubscribe })

    let stale = false
    await dispatcher.callRequest('fs.watch', { rootPath: tmpDir }, { isStale: () => stale })
    stale = true
    await dispatcher.callRequest('fs.watch', { rootPath: tmpDir }, { isStale: () => false })

    expect(firstUnsubscribe).toHaveBeenCalled()
    expect(secondUnsubscribe).not.toHaveBeenCalled()
    dispatcher.callNotification('fs.unwatch', { rootPath: tmpDir })
    expect(secondUnsubscribe).toHaveBeenCalled()
  })

  it('replaces a stale watch for the same root before enforcing the watch cap', async () => {
    const firstUnsubscribe = vi.fn()
    const replacementUnsubscribe = vi.fn()
    mockSubscribe
      .mockResolvedValueOnce({ unsubscribe: firstUnsubscribe })
      .mockResolvedValueOnce({ unsubscribe: replacementUnsubscribe })

    let stale = false
    await dispatcher.callRequest('fs.watch', { rootPath: tmpDir }, { isStale: () => stale })
    for (let index = 0; index < 19; index++) {
      await dispatcher.callRequest('fs.watch', {
        rootPath: path.join(tmpDir, `watched-${index}`)
      })
    }

    stale = true
    await dispatcher.callRequest('fs.watch', { rootPath: tmpDir }, { isStale: () => false })

    expect(firstUnsubscribe).toHaveBeenCalled()
    expect(replacementUnsubscribe).not.toHaveBeenCalled()
  })

  it('removes stale watches for any root before enforcing the watch cap', async () => {
    const staleUnsubscribe = vi.fn()
    mockSubscribe
      .mockResolvedValueOnce({ unsubscribe: staleUnsubscribe })
      .mockResolvedValue({ unsubscribe: vi.fn() })

    let stale = false
    await dispatcher.callRequest(
      'fs.watch',
      { rootPath: path.join(tmpDir, 'stale-root') },
      {
        isStale: () => stale
      }
    )
    for (let index = 0; index < 19; index += 1) {
      await dispatcher.callRequest('fs.watch', {
        rootPath: path.join(tmpDir, `watched-${index}`)
      })
    }

    stale = true

    await expect(
      dispatcher.callRequest('fs.watch', { rootPath: path.join(tmpDir, 'new-root') })
    ).resolves.toBeUndefined()
    expect(staleUnsubscribe).toHaveBeenCalledTimes(1)
  })

  it('keeps a shared watch alive until every client unwatches it', async () => {
    const unsubscribe = vi.fn()
    mockSubscribe.mockResolvedValue({ unsubscribe })

    await dispatcher.callRequest('fs.watch', { rootPath: tmpDir }, { isStale: () => false })
    await dispatcher.callRequest(
      'fs.watch',
      { rootPath: tmpDir },
      {
        clientId: 2,
        isStale: () => false
      }
    )

    dispatcher.callNotification(
      'fs.unwatch',
      { rootPath: tmpDir },
      {
        clientId: 1,
        isStale: () => false
      }
    )
    expect(unsubscribe).not.toHaveBeenCalled()

    dispatcher.callNotification(
      'fs.unwatch',
      { rootPath: tmpDir },
      {
        clientId: 2,
        isStale: () => false
      }
    )
    expect(unsubscribe).toHaveBeenCalledTimes(1)
  })

  it('settles acknowledged unwatch only after native unsubscribe completes', async () => {
    let resolveUnsubscribe: () => void = () => {}
    const unsubscribe = vi.fn(
      () =>
        new Promise<void>((resolve) => {
          resolveUnsubscribe = resolve
        })
    )
    mockSubscribe.mockResolvedValue({ unsubscribe })
    await dispatcher.callRequest('fs.watch', { rootPath: tmpDir })

    let settled = false
    const unwatch = dispatcher.callRequest('fs.unwatchAndWait', { rootPath: tmpDir }).then(() => {
      settled = true
    })
    await vi.waitFor(() => expect(unsubscribe).toHaveBeenCalledTimes(1))
    expect(settled).toBe(false)

    resolveUnsubscribe()
    await unwatch
    expect(settled).toBe(true)
  })

  it('waits for in-flight native setup before acknowledging teardown', async () => {
    handler.dispose()
    let resolveSubscribe: (value: { unsubscribe: () => Promise<void> }) => void = () => {}
    const unsubscribe = vi.fn(async () => undefined)
    const subscribe = vi.fn(
      () =>
        new Promise<{ unsubscribe: () => Promise<void> }>((resolve) => {
          resolveSubscribe = resolve
        })
    )
    handler = new FsHandler(dispatcher as unknown as RelayDispatcher, new RelayContext(), {
      dispose: vi.fn(),
      forgetRoot: vi.fn(),
      subscribe
    })

    const watch = dispatcher.callRequest('fs.watch', { rootPath: tmpDir })
    let unwatchSettled = false
    const unwatch = dispatcher.callRequest('fs.unwatchAndWait', { rootPath: tmpDir }).then(() => {
      unwatchSettled = true
    })
    await vi.waitFor(() => expect(subscribe).toHaveBeenCalledTimes(1))
    expect(unwatchSettled).toBe(false)

    resolveSubscribe({ unsubscribe })
    await Promise.all([watch, unwatch])
    expect(unsubscribe).toHaveBeenCalledTimes(1)
  })

  it('joins a physical unsubscribe already started by the notification path', async () => {
    let resolveUnsubscribe: () => void = () => {}
    const unsubscribe = vi.fn(
      () =>
        new Promise<void>((resolve) => {
          resolveUnsubscribe = resolve
        })
    )
    mockSubscribe.mockResolvedValue({ unsubscribe })
    await dispatcher.callRequest('fs.watch', { rootPath: tmpDir })
    dispatcher.callNotification('fs.unwatch', { rootPath: tmpDir })

    let settled = false
    const joined = dispatcher.callRequest('fs.unwatchAndWait', { rootPath: tmpDir }).then(() => {
      settled = true
    })
    await Promise.resolve()
    expect(settled).toBe(false)

    resolveUnsubscribe()
    await joined
  })

  it('blocks replacement watches behind physical unsubscribe and counts the pending slot', async () => {
    let resolveUnsubscribe: () => void = () => {}
    const unsubscribe = vi.fn(
      () =>
        new Promise<void>((resolve) => {
          resolveUnsubscribe = resolve
        })
    )
    mockSubscribe.mockResolvedValue({ unsubscribe })
    await dispatcher.callRequest('fs.watch', { rootPath: tmpDir })
    dispatcher.callNotification('fs.unwatch', { rootPath: tmpDir })

    const replacement = dispatcher.callRequest('fs.watch', { rootPath: tmpDir })
    for (let index = 0; index < 19; index += 1) {
      await dispatcher.callRequest('fs.watch', {
        rootPath: path.join(tmpDir, `pending-cap-${index}`)
      })
    }
    await expect(
      dispatcher.callRequest('fs.watch', { rootPath: path.join(tmpDir, 'over-pending-cap') })
    ).rejects.toThrow('Maximum number of file watchers reached')
    expect(mockSubscribe).toHaveBeenCalledTimes(20)

    resolveUnsubscribe()
    await replacement
    expect(mockSubscribe).toHaveBeenCalledTimes(21)
  })

  it('retains a failed native unsubscribe slot until acknowledged retry succeeds', async () => {
    const unsubscribe = vi
      .fn()
      .mockRejectedValueOnce(new Error('native handle still active'))
      .mockResolvedValueOnce(undefined)
    mockSubscribe.mockResolvedValue({ unsubscribe })
    await dispatcher.callRequest('fs.watch', { rootPath: tmpDir })

    await expect(dispatcher.callRequest('fs.unwatchAndWait', { rootPath: tmpDir })).rejects.toThrow(
      'native handle still active'
    )
    await expect(
      dispatcher.callRequest('fs.unwatchAndWait', { rootPath: tmpDir })
    ).resolves.toBeUndefined()
    expect(unsubscribe).toHaveBeenCalledTimes(2)

    await expect(dispatcher.callRequest('fs.watch', { rootPath: tmpDir })).resolves.toBeUndefined()
    expect(mockSubscribe).toHaveBeenCalledTimes(2)
  })

  it('allows a shared watch attach even when the root watch cap is full', async () => {
    mockSubscribe.mockResolvedValue({ unsubscribe: vi.fn() })

    for (let index = 0; index < 20; index += 1) {
      const dir = path.join(tmpDir, `watched-${index}`)
      await fs.mkdir(dir)
      await dispatcher.callRequest(
        'fs.watch',
        { rootPath: dir },
        {
          clientId: index + 1,
          isStale: () => false
        }
      )
    }

    await expect(
      dispatcher.callRequest(
        'fs.watch',
        { rootPath: path.join(tmpDir, 'watched-0') },
        {
          clientId: 99,
          isStale: () => false
        }
      )
    ).resolves.toBeUndefined()
  })

  it('releases a client watch when the dispatcher detaches that client', async () => {
    const unsubscribe = vi.fn()
    mockSubscribe.mockResolvedValue({ unsubscribe })

    await dispatcher.callRequest(
      'fs.watch',
      { rootPath: tmpDir },
      {
        clientId: 7,
        isStale: () => false
      }
    )
    dispatcher.detachClient(7)

    expect(unsubscribe).toHaveBeenCalledTimes(1)
  })
})