[BUG] ExitPlanMode denied under --dangerously-skip-permissions while EnterPlanMode is auto-approved

Bug Description

--dangerously-skip-permissions (and bypassPermissions mode) auto-approves EnterPlanMode but denies ExitPlanMode. This creates a one-way trap in --print mode: Claude enters plan mode but can never exit it, gets stuck, and the subprocess ends without implementing anything.

Expected Behavior

Either:

1. Both auto-approved under --dangerously-skip-permissions (preferred — plan mode improves output quality, and there's no interactive user to approve the exit), or
2. Both denied (so Claude never enters a state it can't exit)

Actual Behavior

• EnterPlanMode: auto-approved (permissionMode changes to "plan")
• ExitPlanMode: denied with {"is_error": true, "content": "Exit plan mode?"}
• ExitPlanMode appears in permission_denials in the result

Reproduction

Minimal repro (requires jq):

echo '{"type":"user","message":{"role":"user","content":"You MUST enter plan mode first. Plan a hello world python script. Then exit plan mode and implement it."}}' \
| claude -p \
  --dangerously-skip-permissions \
  --input-format stream-json \
  --output-format stream-json \
  --verbose \
  --no-session-persistence \
  2>&1 \
| jq -c 'select(
    (.type == "system" and .subtype == "status" and has("permissionMode")) or
    (.type == "user" and (.message.content | type == "array") and (.message.content[0].is_error == true)) or
    (.type == "result" and has("permission_denials"))
  )'

Output (3 lines — enter succeeds, exit denied, denial confirmed):

{"type":"system","subtype":"status","status":null,"permissionMode":"plan",...}
{"type":"user","message":{"role":"user","content":[{"type":"tool_result","content":"Exit plan mode?","is_error":true,...}]},...}
{"type":"result",...,"permission_denials":[{"tool_name":"ExitPlanMode","tool_input":{"plan":"..."}}]}

Impact

This affects any claude -p subprocess workflow where Claude's CLAUDE.md instructions encourage using EnterPlanMode for non-trivial tasks. The subprocess enters plan mode (following instructions), gets stuck, and returns without implementing anything.

Current workaround: --disallowedTools "EnterPlanMode" "ExitPlanMode" — but this removes planning capability entirely rather than allowing it to work headlessly.

Environment

• Claude Code version: 2.1.42
• Platform: macOS (Darwin 25.2.0)
• Model: claude-opus-4-6