Method createCanUseTool

source code/cli/structuredIO.ts:535–661

(
    onPermissionPrompt?: (details: RequiresActionDetails) => void,
  )

  }

  createCanUseTool(
    onPermissionPrompt?: (details: RequiresActionDetails) => void,
  ): CanUseToolFn {
    return async (
      tool: Tool,
      input: { [key: string]: unknown },
      toolUseContext: ToolUseContext,
      assistantMessage: AssistantMessage,
      toolUseID: string,
      forceDecision?: PermissionDecision,
    ): Promise<PermissionDecision> => {
      const mainPermissionResult =
        forceDecision ??
        (await hasPermissionsToUseTool(
          tool,
          input,
          toolUseContext,
          assistantMessage,
          toolUseID,
        ))
      // If the tool is allowed or denied, return the result
      if (
        mainPermissionResult.behavior === 'allow' ||
        mainPermissionResult.behavior === 'deny'
      ) {
        return mainPermissionResult
      }

      // Run PermissionRequest hooks in parallel with the SDK permission
      // prompt.  In the terminal CLI, hooks race against the interactive
      // prompt so that e.g. a hook with --delay 20 doesn't block the UI.
      // We need the same behavior here: the SDK host (VS Code, etc.) shows
      // its permission dialog immediately while hooks run in the background.
      // Whichever resolves first wins; the loser is cancelled/ignored.

      // AbortController used to cancel the SDK request if a hook decides first
      const hookAbortController = new AbortController()
      const parentSignal = toolUseContext.abortController.signal
      // Forward parent abort to our local controller
      const onParentAbort = () => hookAbortController.abort()
      parentSignal.addEventListener('abort', onParentAbort, { once: true })

      try {
        // Start the hook evaluation (runs in background)
        const hookPromise = executePermissionRequestHooksForSDK(
          tool.name,
          toolUseID,
          input,
          toolUseContext,
          mainPermissionResult.suggestions,
        ).then(decision => ({ source: 'hook' as const, decision }))

        // Start the SDK permission prompt immediately (don't wait for hooks)
        const requestId = randomUUID()
        onPermissionPrompt?.(
          buildRequiresActionDetails(tool, input, toolUseID, requestId),
        )
        const sdkPromise = this.sendRequest<PermissionToolOutput>(