fix(claude): auto-approve ExitPlanMode via canUseTool

[floodsung]

Problem

When the Claude agent enters plan mode and tries to exit it (via the ExitPlanMode tool), the Feishu bridge gets stuck — the user sees a perpetual "Exit plan mode?" prompt with no way to answer it, and the only escape is Ctrl+C on the bridge process.

Root cause: ExitPlanMode's native checkPermissions returns {behavior: "ask", message: "Exit plan mode?"} outside sub-agent contexts, even under permissionMode: 'bypassPermissions'. That "ask" is routed by the SDK through the can_use_tool control_request — not through PreToolUse hooks. Without a canUseTool handler, the bridge has nothing to reply with, the SDK gives back an is_error tool_result, and the plan-mode gate never lifts.

Extracted from the SDK binary:

async checkPermissions(H, $) {
  if ($A()) return { behavior: "allow", updatedInput: H };
  return { behavior: "ask", message: "Exit plan mode?", updatedInput: H };
}

Fix

Wire a canUseTool callback on the SDK query options for both ClaudeExecutor and PersistentClaudeExecutor that auto-allows ExitPlanMode (and any other unexpected "ask" as a safety net). The user still sees the plan body — the bridge already ships it as a separate card via StreamProcessor + sendPlanContent before this gate is hit.

Two SDK gotchas worth keeping in mind

1. PreToolUse hook allow does NOT bypass canUseTool's ask. They're two independent gates. PreToolUse: deny short-circuits canUseTool, but allow doesn't. So { matcher: 'ExitPlanMode', hooks: [hook that returns allow] } would log "auto-approving" but never unblock anything.

2. The allow branch of canUseTool MUST include updatedInput: Record<string, unknown>. The SDK Zod-validates the response and rejects {behavior: 'allow'} alone with ZodError: invalid_type expected record, received undefined at updatedInput. Echo input back when there's no mutation to apply.

Tests

tests/exit-plan-mode-auto-approve.test.ts asserts the full return shape (not just behavior) so a regression on (2) would fail the suite — an earlier iteration passed toEqual({behavior:'allow'}) against the broken shape because toEqual is structural and missing keys are silently OK.

 ✓ tests/exit-plan-mode-auto-approve.test.ts (5 tests) 4ms

Also verified end-to-end on the internal bridge: EnterPlanMode → ExitPlanMode now succeeds silently, with no Tool permission request failed: ZodError and no perpetual "Exit plan mode?" loop.

🤖 Generated with Claude Code