claude-print/notes/bf-2w7-implementation-summary.md

BF-2W7: Cleanup Implementation Summary

Task

Always tear down temp dir + stop.fifo on every exit path; sweep orphans on startup.

Implementation Status: ✅ COMPLETE

All requirements have been implemented and tested:

1. Orphan Cleanup on Startup ✅

• Function: hook::cleanup_orphans() in src/hook.rs:9-57
• Called: main.rs:43 - early in main(), before any session runs
• Behavior: Sweeps /tmp/claude-print-* directories older than 60 seconds, removes FIFO first then entire directory

2. CleanupGuard RAII Pattern ✅

• Struct: CleanupGuard<'a> in src/session.rs:47-53
• Drop Implementation: Calls installer.cleanup() when guard is dropped
• Coverage: All exit paths where guard goes out of scope (success, error, timeout, signal, panic)

3. Global Cleanup Before process::exit() ✅

• Function: session::cleanup_temp_dir() in src/session.rs:60-98
• Wrapper: exit_with_cleanup() in main.rs:30-33
• Behavior: Idempotent via atomic swap, removes FIFO first, retry logic (3 attempts, 10ms delays)
• Called: Before every process::exit() call in all exit paths

4. Atexit Handler Registration ✅

• Function: session::register_cleanup_handler() in src/session.rs:106-115
• Called: main.rs:38 - very early in startup
• Behavior: Registers libc::atexit() handler to call cleanup_temp_dir() even if Rust's default signal handler triggers

5. Signal Handling (SIGINT/SIGTERM) ✅

• Handlers: sigint_handler and sigterm_handler in src/session.rs:464-486
• Mechanism: Write to self-pipe → event loop returns ExitReason::Interrupted → CleanupGuard drops
• SignalGuard: Restores default handlers on drop

6. HookInstaller Cleanup Method ✅

• Function: HookInstaller::cleanup() in src/hook.rs:122-163
• Behavior: Idempotent via Arc<AtomicBool>, removes FIFO first, retry logic for directory removal
• Called: Automatically by CleanupGuard::drop

7. Panic Safety ✅

• Implementation: std::panic::catch_unwind in Session::run() (session.rs:154-173)
• Behavior: Panic caught → CleanupGuard drops → cleanup runs

Test Coverage

All tests pass:

• ✅ 90 library tests (including cleanup_can_be_called_multiple_times, cleanup_orphans_does_not_panic)
• ✅ 28 integration tests (including invariant_temp_dir_drop_removes_all_artifacts)

Exit Path Coverage Matrix

Exit Path	Cleanup Mechanism	Status
Normal exit	exit_with_cleanup() + CleanupGuard::drop	✅
Error exit	exit_with_cleanup() + CleanupGuard::drop	✅
Watchdog timeout	Self-pipe → Event loop exit → CleanupGuard::drop	✅
SIGTERM	Signal handler → self-pipe → Interrupted → CleanupGuard::drop	✅
SIGINT	Signal handler → self-pipe → Interrupted → CleanupGuard::drop	✅
Panic	catch_unwind → CleanupGuard::drop	✅
Orphan cleanup on startup	cleanup_orphans()	✅

Implementation Details

FIFO Removal Strategy

The FIFO (named pipe) is removed before the directory because:

1. FIFOs have different permissions that can block directory removal
2. Must be explicitly removed (not part of normal directory tree)
3. Retry logic handles transient errors

Retry Logic

Both cleanup_temp_dir() and HookInstaller::cleanup() use retry logic:

• 3 attempts with 5-10ms delays between attempts
• Prevents failures due to temporary file locks or access delays

Idempotency

Both cleanup mechanisms are idempotent:

• cleanup_temp_dir() uses AtomicBool::swap to prevent double cleanup
• HookInstaller::cleanup() uses Arc<AtomicBool> flag
• Safe to call multiple times without side effects

Conclusion

The implementation provides defense in depth with multiple redundant cleanup mechanisms:

1. RAII CleanupGuard (always runs when Session::run_inner returns)
2. Global TEMP_DIR_PATH with cleanup_temp_dir() (for process::exit paths)
3. HookInstaller::cleanup() with idempotent flag and retry logic
4. Atexit handler for external signal cases
5. Startup orphan sweeping to prevent accumulation

All exit paths are covered, ensuring no orphaned temp directories or FIFOs remain after any termination scenario.

Files Modified

• src/hook.rs: Added cleanup_orphans() function and enhanced HookInstaller::cleanup()
• src/session.rs: Added CleanupGuard, cleanup_temp_dir(), register_cleanup_handler()
• src/main.rs: Added exit_with_cleanup() wrapper, registered cleanup handlers, called cleanup_orphans()
• tests/: Integration tests verify cleanup behavior

Verification

Run: cargo test - All 90 library tests + 28 integration tests pass