Function execCommandHook

source code/utils/hooks.ts:749–1337

* Execute a command-based hook using bash or PowerShell. * * Shell resolution: hook.shell → 'bash'. PowerShell hooks spawn pwsh * with -NoProfile -NonInteractive -Command and skip bash-specific prep * (POSIX path conversion, .sh auto-prepend, CLAUDE_CODE_SHELL_PREFIX). * See docs/design/ps-shel

(
  hook: HookCommand & { type: 'command' },
  hookEvent: HookEvent | 'StatusLine' | 'FileSuggestion',
  hookName: string,
  jsonInput: string,
  signal: AbortSignal,
  hookId: string,
  hookIndex?: number,
  pluginRoot?: string,
  pluginId?: string,
  skillRoot?: string,
  forceSyncExecution?: boolean,
  requestPrompt?: (request: PromptRequest) => Promise<PromptResponse>,
)

 * See docs/design/ps-shell-selection.md §5.1.
 */
async function execCommandHook(
  hook: HookCommand & { type: 'command' },
  hookEvent: HookEvent | 'StatusLine' | 'FileSuggestion',
  hookName: string,
  jsonInput: string,
  signal: AbortSignal,
  hookId: string,
  hookIndex?: number,
  pluginRoot?: string,
  pluginId?: string,
  skillRoot?: string,
  forceSyncExecution?: boolean,
  requestPrompt?: (request: PromptRequest) => Promise<PromptResponse>,
): Promise<{
  stdout: string
  stderr: string
  output: string
  status: number
  aborted?: boolean
  backgrounded?: boolean
}> {
  // Gated to once-per-session events to keep diag_log volume bounded.
  // started/completed live inside the try/finally so setup-path throws
  // don't orphan a started marker — that'd be indistinguishable from a hang.
  const shouldEmitDiag =
    hookEvent === 'SessionStart' ||
    hookEvent === 'Setup' ||
    hookEvent === 'SessionEnd'
  const diagStartMs = Date.now()
  let diagExitCode: number | undefined
  let diagAborted = false

  const isWindows = getPlatform() === 'windows'

  // --
  // Per-hook shell selection (phase 1 of docs/design/ps-shell-selection.md).
  // Resolution order: hook.shell → DEFAULT_HOOK_SHELL. The defaultShell
  // fallback (settings.defaultShell) is phase 2 — not wired yet.
  //
  // The bash path is the historical default and stays unchanged. The
  // PowerShell path deliberately skips the Windows-specific bash
  // accommodations (cygpath conversion, .sh auto-prepend, POSIX-quoted
  // SHELL_PREFIX).
  const shellType = hook.shell ?? DEFAULT_HOOK_SHELL

  const isPowerShell = shellType === 'powershell'

  // --
  // Windows bash path: hooks run via Git Bash (Cygwin), NOT cmd.exe.
  //
  // This means every path we put into env vars or substitute into the command
  // string MUST be a POSIX path (/c/Users/foo), not a Windows path
  // (C:\Users\foo or C:/Users/foo). Git Bash cannot resolve Windows paths.
  //
  // windowsPathToPosixPath() is pure-JS regex conversion (no cygpath shell-out):
  // C:\Users\foo -> /c/Users/foo, UNC preserved, slashes flipped. Memoized
  // (LRU-500) so repeated calls are cheap.
  //