Add event-driven daemon architecture (Phase 1 foundation)

- Add fsnotify dependency for file watching - Create daemon_debouncer.go: batch rapid events (500ms window) - Create daemon_watcher.go: monitor JSONL and git refs changes - Create daemon_event_loop.go: event-driven sync loop - Add mutation channel to RPC server (create/update/close events) - Add BEADS_DAEMON_MODE env var (poll/events, default: poll) Phase 1 implementation: opt-in via BEADS_DAEMON_MODE=events Target: <500ms latency (vs 5000ms), ~60% CPU reduction Related: bd-49 (epic), bd-50, bd-51, bd-53, bd-54, bd-55, bd-56 Amp-Thread-ID: https://ampcode.com/threads/T-35a3d0d7-4e19-421d-8392-63755035036e Co-authored-by: Amp <amp@ampcode.com>
2025-10-28 13:12:37 -07:00
parent 97c676077d
commit 781e300d33
8 changed files with 2527 additions and 1 deletions
--- a/cmd/bd/daemon_watcher.go
+++ b/cmd/bd/daemon_watcher.go
@@ -0,0 +1,97 @@
+package main
+
+import (
+	"context"
+	"fmt"
+	"path/filepath"
+	"time"
+
+	"github.com/fsnotify/fsnotify"
+)
+
+// FileWatcher monitors JSONL and git ref changes using filesystem events.
+type FileWatcher struct {
+	watcher   *fsnotify.Watcher
+	debouncer *Debouncer
+	jsonlPath string
+}
+
+// NewFileWatcher creates a file watcher for the given JSONL path.
+// onChanged is called when the file or git refs change, after debouncing.
+func NewFileWatcher(jsonlPath string, onChanged func()) (*FileWatcher, error) {
+	watcher, err := fsnotify.NewWatcher()
+	if err != nil {
+		return nil, err
+	}
+
+	fw := &FileWatcher{
+		watcher:   watcher,
+		jsonlPath: jsonlPath,
+		debouncer: NewDebouncer(500*time.Millisecond, onChanged),
+	}
+
+	// Watch the JSONL file
+	if err := watcher.Add(jsonlPath); err != nil {
+		watcher.Close()
+		return nil, fmt.Errorf("failed to watch JSONL: %w", err)
+	}
+
+	// Also watch .git/refs/heads for branch changes (best effort)
+	gitRefsPath := filepath.Join(filepath.Dir(jsonlPath), "..", ".git", "refs", "heads")
+	_ = watcher.Add(gitRefsPath) // Ignore error - not all setups have this
+
+	return fw, nil
+}
+
+// Start begins monitoring filesystem events.
+// Runs in background goroutine until context is canceled.
+func (fw *FileWatcher) Start(ctx context.Context, log daemonLogger) {
+	go func() {
+		for {
+			select {
+			case event, ok := <-fw.watcher.Events:
+				if !ok {
+					return
+				}
+
+				// Handle JSONL write events
+				if event.Name == fw.jsonlPath && event.Op&fsnotify.Write != 0 {
+					log.log("File change detected: %s", event.Name)
+					fw.debouncer.Trigger()
+				}
+
+				// Handle JSONL removal/rename (e.g., git checkout)
+				if event.Name == fw.jsonlPath && (event.Op&fsnotify.Remove != 0 || event.Op&fsnotify.Rename != 0) {
+					log.log("JSONL removed/renamed, re-establishing watch")
+					fw.watcher.Remove(fw.jsonlPath)
+					// Brief wait for file to be recreated
+					time.Sleep(100 * time.Millisecond)
+					if err := fw.watcher.Add(fw.jsonlPath); err != nil {
+						log.log("Failed to re-watch JSONL: %v", err)
+					}
+				}
+
+				// Handle git ref changes
+				if event.Op&fsnotify.Write != 0 && filepath.Dir(event.Name) != filepath.Dir(fw.jsonlPath) {
+					log.log("Git ref change detected: %s", event.Name)
+					fw.debouncer.Trigger()
+				}
+
+			case err, ok := <-fw.watcher.Errors:
+				if !ok {
+					return
+				}
+				log.log("Watcher error: %v", err)
+
+			case <-ctx.Done():
+				return
+			}
+		}
+	}()
+}
+
+// Close stops the file watcher and releases resources.
+func (fw *FileWatcher) Close() error {
+	fw.debouncer.Cancel()
+	return fw.watcher.Close()
+}