fix: reclaim cancelFns, TTL idemLocks, cache scope probe, invalidate C1, SSE subscribe order

Close T20-B2/B6/B8/B9/B10 low-risk leaks: map-backed cancel reclaim, idempotency lock TTL in cleanupLoop, sync.Once information_schema probe, InvalidateLayer after chat memory upsert, and Subscribe before SSE headers.

internal/ctxmgr/chat_memory.go

@@ -147,6 +147,8 @@ func (m *ContextManager) RecordTurnMemoryWithVisibility(
 		if err != nil {
 			return 0, fmt.Errorf("insert chat memory chunk to db failed: %w", err)
 		}
+		// C1 search cache keys include query text; drop the layer so new chunks are visible.
+		m.Cache().InvalidateLayer(LayerC1Search)
 		return chunkID, nil
 	}
 
@@ -184,6 +186,7 @@ func (m *ContextManager) RecordTurnMemoryWithVisibility(
 		m.memoryChunks = append(m.memoryChunks, item)
 	}
 
+	m.Cache().InvalidateLayer(LayerC1Search)
 	return chunkID, nil
 }
 

internal/ctxmgr/manager.go

@@ -39,6 +39,10 @@ type ContextManager struct {
 	nextActivityID     int64
 	nextMessageID      int64
 	nextChunkID        int64
+
+	// message scope column probe (information_schema); cached once per manager
+	messageScopeOnce sync.Once
+	messageScopeOK   bool
 }
 
 // NewContextManager 创建上下文管理器

internal/ctxmgr/message_scope_io.go

@@ -25,14 +25,17 @@ func (m *ContextManager) hasMessageScopeColumns(ctx context.Context) bool {
 	if m == nil || m.pool == nil {
 		return false
 	}
-	var ok bool
-	_ = m.pool.QueryRow(ctx, `
-		SELECT EXISTS (
-			SELECT 1 FROM information_schema.columns
-			WHERE table_schema = 'public' AND table_name = 'chat_messages' AND column_name = 'scope_kind'
-		)
-	`).Scan(&ok)
-	return ok
+	m.messageScopeOnce.Do(func() {
+		var ok bool
+		_ = m.pool.QueryRow(ctx, `
+			SELECT EXISTS (
+				SELECT 1 FROM information_schema.columns
+				WHERE table_schema = 'public' AND table_name = 'chat_messages' AND column_name = 'scope_kind'
+			)
+		`).Scan(&ok)
+		m.messageScopeOK = ok
+	})
+	return m.messageScopeOK
 }
 
 func (m *ContextManager) chatMessageSelectColumns(ctx context.Context) string {