Merge pull request #1362 from trungutt/fix/subsession-persistence

Fix sub-sessions being saved as standalone entries

Author: rumpl

pkg/runtime/runtime.go

@@ -709,7 +709,7 @@ func (r *LocalRuntime) RunStream(ctx context.Context, sess *session.Session) <-c
 							CreatedAt: time.Now().Format(time.RFC3339),
 						}
 						sess.AddMessage(session.NewAgentMessage(a, &assistantMessage))
-						_ = r.sessionStore.UpdateSession(ctx, sess)
+						r.saveSession(ctx, sess)
 						return
 					}
 				case <-ctx.Done():
@@ -840,7 +840,7 @@ func (r *LocalRuntime) RunStream(ctx context.Context, sess *session.Session) <-c
 				}
 
 				sess.AddMessage(session.NewAgentMessage(a, &assistantMessage))
-				_ = r.sessionStore.UpdateSession(ctx, sess)
+				r.saveSession(ctx, sess)
 				slog.Debug("Added assistant message to session", "agent", a.Name(), "total_messages", len(sess.GetAllMessages()))
 			} else {
 				slog.Debug("Skipping empty assistant message (no content and no tool calls)", "agent", a.Name())
@@ -1419,7 +1419,7 @@ func (r *LocalRuntime) executeToolWithHandler(
 		CreatedAt:  time.Now().Format(time.RFC3339),
 	}
 	sess.AddMessage(session.NewAgentMessage(a, &toolResponseMsg))
-	_ = r.sessionStore.UpdateSession(ctx, sess)
+	r.saveSession(ctx, sess)
 }
 
 // runTool executes agent tools from toolsets (MCP, filesystem, etc.).
@@ -1510,6 +1510,16 @@ func (r *LocalRuntime) addToolErrorResponse(ctx context.Context, sess *session.S
 		CreatedAt:  time.Now().Format(time.RFC3339),
 	}
 	sess.AddMessage(session.NewAgentMessage(a, &toolResponseMsg))
+	r.saveSession(ctx, sess)
+}
+
+// saveSession persists the session to the store, but only for root sessions.
+// Sub-sessions (those with a ParentID) are not persisted as standalone entries;
+// they are embedded within the parent session's Messages array.
+func (r *LocalRuntime) saveSession(ctx context.Context, sess *session.Session) {
+	if sess.IsSubSession() {
+		return
+	}
 	_ = r.sessionStore.UpdateSession(ctx, sess)
 }
 
@@ -1587,6 +1597,7 @@ func (r *LocalRuntime) handleTaskTransfer(ctx context.Context, sess *session.Ses
 		session.WithTitle("Transferred task"),
 		session.WithToolsApproved(sess.ToolsApproved),
 		session.WithSendUserMessage(false),
+		session.WithParentID(sess.ID),
 	)
 
 	for event := range r.RunStream(ctx, s) {

pkg/session/session.go

@@ -94,6 +94,11 @@ type Session struct {
 	// CustomModelsUsed tracks custom models (provider/model format) used during this session.
 	// These are shown in the model picker for easy re-selection.
 	CustomModelsUsed []string `json:"custom_models_used,omitempty"`
+
+	// ParentID indicates this is a sub-session created by task transfer.
+	// Sub-sessions are not persisted as standalone entries; they are embedded
+	// within the parent session's Messages array.
+	ParentID string `json:"-"`
 }
 
 // Permission mode constants
@@ -357,6 +362,19 @@ func WithPermissions(perms *PermissionsConfig) Opt {
 	}
 }
 
+// WithParentID marks this session as a sub-session of the given parent.
+// Sub-sessions are not persisted as standalone entries in the session store.
+func WithParentID(parentID string) Opt {
+	return func(s *Session) {
+		s.ParentID = parentID
+	}
+}
+
+// IsSubSession returns true if this session is a sub-session (has a parent).
+func (s *Session) IsSubSession() bool {
+	return s.ParentID != ""
+}
+
 // New creates a new agent session
 func New(opts ...Opt) *Session {
 	sessionID := uuid.New().String()