feat(taskrun): finalize RunManifest in one unit of work

CAS the unique terminal status with the assistant turn, frozen manifest, envelope and FAV staging, and join ctxmgr writes through the same UoW instead of a process mutex.

Co-authored-by: Cursor <cursoragent@cursor.com>

internal/ctxmgr/message_update.go

@@ -5,6 +5,11 @@ import (
 	"encoding/json"
 	"errors"
 	"fmt"
+
+	"chat-agent-system/internal/app/uow"
+
+	"github.com/jackc/pgx/v5/pgconn"
+	"github.com/jackc/pgx/v5/pgxpool"
 )
 
 // UpdateMessageMetadata 更新已持久化助手消息的 metadata 与任务状态。
@@ -19,9 +24,9 @@ func (m *ContextManager) UpdateMessageMetadata(ctx context.Context, messageID in
 		meta["task_status"] = taskStatus
 	}
 
-	if m.pool != nil {
+	if m.pool != nil || hasUoW(ctx) {
 		metaJSON, _ := json.Marshal(meta)
-		_, err := m.pool.Exec(ctx, `
+		_, err := execChat(ctx, m.pool, `
 			UPDATE chat_messages
 			SET metadata = COALESCE(metadata, '{}'::jsonb) || $1::jsonb
 			WHERE id = $2
@@ -63,12 +68,12 @@ func (m *ContextManager) FinalizeAssistantTaskMessage(ctx context.Context, messa
 		meta["task_status"] = taskStatus
 	}
 
-	if m.pool != nil {
+	if m.pool != nil || hasUoW(ctx) {
 		metaJSON, err := json.Marshal(meta)
 		if err != nil {
 			return fmt.Errorf("marshal metadata failed: %w", err)
 		}
-		tag, err := m.pool.Exec(ctx, `
+		tag, err := execChat(ctx, m.pool, `
 			UPDATE chat_messages
 			SET content = $1,
 			    metadata = COALESCE(metadata, '{}'::jsonb) || $2::jsonb
@@ -102,3 +107,22 @@ func (m *ContextManager) FinalizeAssistantTaskMessage(ctx context.Context, messa
 	}
 	return errors.New("message not found")
 }
+
+func hasUoW(ctx context.Context) bool {
+	_, ok := uow.ScopeFrom(ctx)
+	return ok
+}
+
+func execChat(ctx context.Context, pool *pgxpool.Pool, q string, args ...any) (pgconn.CommandTag, error) {
+	if scope, ok := uow.ScopeFrom(ctx); ok {
+		tx, err := uow.AsPG(scope)
+		if err != nil {
+			return pgconn.CommandTag{}, err
+		}
+		return tx.Exec(ctx, q, args...)
+	}
+	if pool == nil {
+		return pgconn.CommandTag{}, errors.New("ctxmgr: database required")
+	}
+	return pool.Exec(ctx, q, args...)
+}