fix(agent): keep suspended-task snapshots on the legacy stack

suspendActiveContexts clears all active contexts after parking a task on
the snapshot stack, so the active-context guard alone let the agentic
loop hijack resume requests and strand suspended tasks. Check the
snapshot stack in shouldUseAgenticTurn.

agent/agentic_loop.go

@@ -46,6 +46,11 @@ func (a *Agent) shouldUseAgenticTurn(userID int64) bool {
 	if _, ok := a.getPendingProposalSession(userID); ok {
 		return false
 	}
+	// Suspended tasks are parked on the snapshot stack with all active
+	// contexts cleared; only the legacy router knows how to resume them.
+	if len(a.SnapshotManager(userID).Stack()) > 0 {
+		return false
+	}
 	return true
 }
 

agent/agentic_loop_test.go

@@ -274,6 +274,26 @@ func TestShouldUseAgenticTurn(t *testing.T) {
 		}
 	})
 
+	t.Run("suspended task snapshot stays on legacy stack", func(t *testing.T) {
+		st, err := store.New(filepath.Join(t.TempDir(), "agentic-snapshot.db"))
+		if err != nil {
+			t.Fatalf("create store: %v", err)
+		}
+		b := New(nil, st, DefaultConfig(), slog.Default())
+		b.SetAIClient(&scriptedAIClient{})
+		if !b.shouldUseAgenticTurn(12) {
+			t.Fatal("fresh conversation should use the agentic turn")
+		}
+		b.SnapshotManager(12).Save(SuspendedTask{
+			SnapshotID: "snap_test",
+			Kind:       "skill",
+			ResumeHint: "continue strategy create",
+		})
+		if b.shouldUseAgenticTurn(12) {
+			t.Fatal("suspended task snapshot must stay on the legacy stack so it can be resumed")
+		}
+	})
+
 	t.Run("active legacy session stays on legacy stack", func(t *testing.T) {
 		st, err := store.New(filepath.Join(t.TempDir(), "agentic-guard.db"))
 		if err != nil {