feat(go): enrich snapshots asynchronously

go-agent/internal/snapshot/store.go

@@ -67,9 +67,18 @@ type Store struct {
 	LineageDepth int
 	Assurance    *assurance.Chain
 
+	slowJobs   chan slowJob
+	slowClosed bool
+	slowWG     sync.WaitGroup
+
 	mu sync.Mutex
 }
 
+type slowJob struct {
+	jsonPath string
+	logPath  string
+}
+
 // New preflights the isolated snapshot directory before service readiness.
 func New(dir, procRoot string, maxCount, maxAgeDays int) (*Store, error) {
 	if dir == "" {
@@ -126,6 +135,36 @@ func (s *Store) ConfigureIncidents(enabled bool, window, lineageDepth int) error
 	return nil
 }
 
+// EnableSlowEnrichment starts one bounded worker. It deliberately never runs
+// package-manager commands: queue saturation or collector failure only leaves
+// fields unknown and can never delay or reject an alert event.
+func (s *Store) EnableSlowEnrichment() {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	if s.slowJobs != nil || s.slowClosed {
+		return
+	}
+	s.slowJobs = make(chan slowJob, 16)
+	go s.runSlowEnrichment(s.slowJobs)
+}
+
+// Close drains accepted slow-enrichment work during a clean service shutdown.
+func (s *Store) Close() {
+	s.mu.Lock()
+	if s.slowJobs == nil || s.slowClosed {
+		s.mu.Unlock()
+		return
+	}
+	close(s.slowJobs)
+	s.slowClosed = true
+	s.mu.Unlock()
+	s.slowWG.Wait()
+}
+
+// FlushSlow waits for work accepted before the call. It is used by clean
+// shutdown/tests; alert emission never waits for this collector.
+func (s *Store) FlushSlow() { s.slowWG.Wait() }
+
 // CaptureEvent merges one alert envelope into its second-granularity snapshot.
 // Python filenames use second precision, so merging avoids overwriting sibling
 // alerts emitted by one poll sweep or concurrent kernel sources.
@@ -200,9 +239,112 @@ func (s *Store) CaptureEvent(event map[string]any) (string, error) {
 	if err := s.pruneLocked(); err != nil {
 		return "", err
 	}
+	s.enqueueSlow(slowJob{jsonPath: jsonPath, logPath: base + ".log"})
 	return filepath.Base(base + ".log"), nil
 }
 
+func (s *Store) enqueueSlow(job slowJob) {
+	if s.slowJobs == nil || s.slowClosed {
+		return
+	}
+	s.slowWG.Add(1)
+	select {
+	case s.slowJobs <- job:
+	default:
+		s.slowWG.Done()
+	}
+}
+
+func (s *Store) runSlowEnrichment(jobs <-chan slowJob) {
+	for job := range jobs {
+		s.applySlowEnrichment(job)
+		s.slowWG.Done()
+	}
+}
+
+func (s *Store) applySlowEnrichment(job slowJob) {
+	raw, err := os.ReadFile(job.jsonPath)
+	if err != nil {
+		return
+	}
+	var report Report
+	if json.Unmarshal(raw, &report) != nil || report.Schema != Schema {
+		return
+	}
+	processes := enrichmentProcesses(report.Processes)
+	paths := enrichmentPaths(report.Enrichment)
+	updates := enrich.CollectSlow(processes, paths)
+
+	// All slow I/O has completed. Take the lock only to merge into the newest
+	// same-second report, so a concurrent alert capture never loses evidence.
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	raw, err = os.ReadFile(job.jsonPath)
+	if err != nil || json.Unmarshal(raw, &report) != nil || report.Schema != Schema {
+		return
+	}
+	mergeSlow(&report, updates)
+	if err := writeJSONAtomic(job.jsonPath, report); err != nil {
+		return
+	}
+	if err := writeAtomic(job.logPath, []byte(formatText(report))); err != nil {
+		return
+	}
+	if s.Assurance != nil {
+		captured, err := time.Parse(time.RFC3339Nano, report.Time)
+		if err != nil {
+			return
+		}
+		_, _ = s.Assurance.Append("snapshot-log", job.logPath, captured)
+		_, _ = s.Assurance.Append("snapshot-json", job.jsonPath, captured)
+	}
+}
+
+func enrichmentPaths(value map[string]any) []string {
+	rows, _ := value["files"].([]any)
+	paths := make([]string, 0, len(rows))
+	for _, row := range rows {
+		if item, ok := row.(map[string]any); ok {
+			if path, ok := item["path"].(string); ok && path != "" {
+				paths = append(paths, path)
+			}
+		}
+	}
+	return paths
+}
+
+func mergeSlow(report *Report, updates enrich.SlowResult) {
+	if report.Enrichment == nil {
+		return
+	}
+	if rows, ok := report.Enrichment["processes"].([]any); ok {
+		for _, row := range rows {
+			item, ok := row.(map[string]any)
+			if !ok {
+				continue
+			}
+			pid, _ := item["pid"].(float64)
+			if update := updates.Processes[int(pid)]; update != nil {
+				item["exe_sha256"] = update["exe_sha256"]
+			}
+		}
+	}
+	if rows, ok := report.Enrichment["files"].([]any); ok {
+		for _, row := range rows {
+			item, ok := row.(map[string]any)
+			if !ok {
+				continue
+			}
+			path, _ := item["path"].(string)
+			if update := updates.Files[path]; update != nil {
+				for key, value := range update {
+					item[key] = value
+				}
+			}
+		}
+	}
+}
+
 func (s *Store) collectProcesses(alerts []model.Alert) []ProcessDetail {
 	pids := alertPIDs(alerts)
 	result := make([]ProcessDetail, 0, len(pids))