perf: avoid state file frequently write to disk

[gaojunran]

No description provided.

[greptile-apps]

Greptile Summary

This PR introduces a dirty-flag + TOML content-deduplication strategy to batch and skip redundant state-file disk writes. State mutations now go through typed helper methods that set an AtomicBool dirty flag, a 1-second background flush task drains dirty state, and write() compares the serialized TOML string against a cached last_content to skip I/O when nothing has actually changed.

• StateFile gains dirty: AtomicBool and last_content: Mutex<Option<String>>, with a family of mutation methods (insert_daemon, set_active_port, retain_daemons, etc.) that set the flag only when the state actually changes.
• A start_state_flush_task spawns a 1-second ticker with a CancellationToken; shutdown cancels the task and force-flushes any remaining dirty state before IPC teardown.
• handle_ipc now calls flush_state().await after every request so CLI clients can immediately read consistent state from disk; the cron last_cron_triggered write is kept synchronous to close the crash-restart double-fire window flagged in a previous review.

Confidence Score: 5/5

Safe to merge — the flush logic is correct, all mutation paths mark dirty, the background task shuts down cleanly, and the cron crash-safety window is preserved.

The dirty-flag and content-deduplication paths are self-consistent: write() holds the file lock before serializing, compares against cached content, and only skips I/O when the TOML is byte-identical. The shutdown sequence cancels the background task before the force-flush, so the second flush is a no-op via content comparison. All previously raised concerns are addressed in this revision.

No files require special attention.

Important Files Changed

Filename	Overview
src/state_file.rs	Core refactor: adds AtomicBool dirty flag + Mutex-guarded last_content string cache; splits write logic into write()/write_unlocked()/write_raw(); all mutation methods now mark dirty conditionally.
src/supervisor/mod.rs	Adds start_state_flush_task() (1s interval, CancellationToken shutdown) and flush_state(); shutdown sequence cancels the task then force-flushes remaining dirty state.
src/supervisor/ipc_handlers.rs	Adds flush_state().await after every IPC response so CLI readers see consistent on-disk state; early-return path for Invalid requests correctly bypasses the flush.
src/supervisor/lifecycle.rs	Migrates active_port mutation sites to set_active_port/clear_active_port; changes get_mut to get for PID check to satisfy the borrow checker when delegating to &mut self method.
src/supervisor/state.rs	Mechanical migration of all direct state map mutations to the new typed helper methods; removes per-operation write() calls.
src/supervisor/watchers.rs	Cron last_cron_triggered update now uses set_last_cron_triggered() but retains the immediate synchronous write() call, correctly preserving the crash-safety property noted in previous review.

_{Reviews (6): Last reviewed commit: "fix(state): fix write() lock ordering an..." | Re-trigger Greptile}

[gaojunran]

@greptileai

[gaojunran]

@greptileai