fix concurrency and persistence safety in session/cron/heartbeat services

pkg/session/manager.go

@@ -4,6 +4,7 @@ import (
 	"encoding/json"
 	"os"
 	"path/filepath"
+	"strings"
 	"sync"
 	"time"
 
@@ -39,22 +40,22 @@ func NewSessionManager(storage string) *SessionManager {
 }
 
 func (sm *SessionManager) GetOrCreate(key string) *Session {
-	sm.mu.RLock()
-	session, ok := sm.sessions[key]
-	sm.mu.RUnlock()
+	sm.mu.Lock()
+	defer sm.mu.Unlock()
 
-	if !ok {
-		sm.mu.Lock()
-		session = &Session{
-			Key:      key,
-			Messages: []providers.Message{},
-			Created:  time.Now(),
-			Updated:  time.Now(),
-		}
-		sm.sessions[key] = session
-		sm.mu.Unlock()
+	session, ok := sm.sessions[key]
+	if ok {
+		return session
 	}
 
+	session = &Session{
+		Key:      key,
+		Messages: []providers.Message{},
+		Created:  time.Now(),
+		Updated:  time.Now(),
+	}
+	sm.sessions[key] = session
+
 	return session
 }
 
@@ -130,6 +131,12 @@ func (sm *SessionManager) TruncateHistory(key string, keepLast int) {
 		return
 	}
 
+	if keepLast <= 0 {
+		session.Messages = []providers.Message{}
+		session.Updated = time.Now()
+		return
+	}
+
 	if len(session.Messages) <= keepLast {
 		return
 	}
@@ -138,22 +145,78 @@ func (sm *SessionManager) TruncateHistory(key string, keepLast int) {
 	session.Updated = time.Now()
 }
 
-func (sm *SessionManager) Save(session *Session) error {
+func (sm *SessionManager) Save(key string) error {
 	if sm.storage == "" {
 		return nil
 	}
 
-	sm.mu.Lock()
-	defer sm.mu.Unlock()
+	// Validate key to avoid invalid filenames and path traversal.
+	if key == "" || key == "." || key == ".." || key != filepath.Base(key) || strings.Contains(key, "/") || strings.Contains(key, "\\") {
+		return os.ErrInvalid
+	}
 
-	sessionPath := filepath.Join(sm.storage, session.Key+".json")
+	// Snapshot under read lock, then perform slow file I/O after unlock.
+	sm.mu.RLock()
+	stored, ok := sm.sessions[key]
+	if !ok {
+		sm.mu.RUnlock()
+		return nil
+	}
 
-	data, err := json.MarshalIndent(session, "", "  ")
+	snapshot := Session{
+		Key:     stored.Key,
+		Summary: stored.Summary,
+		Created: stored.Created,
+		Updated: stored.Updated,
+	}
+	if len(stored.Messages) > 0 {
+		snapshot.Messages = make([]providers.Message, len(stored.Messages))
+		copy(snapshot.Messages, stored.Messages)
+	} else {
+		snapshot.Messages = []providers.Message{}
+	}
+	sm.mu.RUnlock()
+
+	data, err := json.MarshalIndent(snapshot, "", "  ")
 	if err != nil {
 		return err
 	}
 
-	return os.WriteFile(sessionPath, data, 0644)
+	sessionPath := filepath.Join(sm.storage, key+".json")
+	tmpFile, err := os.CreateTemp(sm.storage, "session-*.tmp")
+	if err != nil {
+		return err
+	}
+
+	tmpPath := tmpFile.Name()
+	cleanup := true
+	defer func() {
+		if cleanup {
+			_ = os.Remove(tmpPath)
+		}
+	}()
+
+	if _, err := tmpFile.Write(data); err != nil {
+		_ = tmpFile.Close()
+		return err
+	}
+	if err := tmpFile.Chmod(0644); err != nil {
+		_ = tmpFile.Close()
+		return err
+	}
+	if err := tmpFile.Sync(); err != nil {
+		_ = tmpFile.Close()
+		return err
+	}
+	if err := tmpFile.Close(); err != nil {
+		return err
+	}
+
+	if err := os.Rename(tmpPath, sessionPath); err != nil {
+		return err
+	}
+	cleanup = false
+	return nil
 }
 
 func (sm *SessionManager) loadSessions() error {