fix(transfer): support PostgreSQL checkpoint CAS

app/db/models/transferpending.py

@@ -10,6 +10,7 @@ from sqlalchemy import (
     Text,
     UniqueConstraint,
     and_,
+    cast as sql_cast,
     column,
     delete,
     exists,
@@ -19,7 +20,9 @@ from sqlalchemy import (
     table,
     update,
 )
+from sqlalchemy.dialects.postgresql import JSONB
 from sqlalchemy.orm import Mapped, Session, mapped_column
+from sqlalchemy.sql.elements import ColumnElement
 
 from app.db.base import Base, execute_dml, get_id_column
 
@@ -389,7 +392,11 @@ class TransferPending(Base):
             now_utc: str,
             updated_at: str,
     ) -> int:
-        """仅以有效租约和完整冻结计划把任务推进或保持为 running。"""
+        """仅以有效租约和完整冻结计划把任务推进或保持为 running。
+
+        PostgreSQL 的 JSON 类型不支持直接等值比较，计划匹配条件会在该方言下
+        临时转换为 JSONB，避免执行 CAS 时触发数据库操作符错误。
+        """
         if not all((
                 task_id,
                 lease_token,
@@ -400,6 +407,10 @@ class TransferPending(Base):
                 updated_at,
         )):
             return 0
+        checkpoint_payload_match = cls._checkpoint_payload_match(
+            db,
+            checkpoint_payload,
+        )
         return execute_dml(
             db,
             update(cls)
@@ -408,7 +419,7 @@ class TransferPending(Base):
                 cls.state == admission_state,
                 cls.state.in_(("planned", "provider_pending")),
                 cls.checkpoint_version == checkpoint_version,
-                cls.checkpoint_payload == checkpoint_payload,
+                checkpoint_payload_match,
                 cls.planned_at.is_not(None),
                 cls.lease_token == lease_token,
                 cls.lease_expires_at.is_not(None),
@@ -424,6 +435,20 @@ class TransferPending(Base):
             execution_options={"synchronize_session": False},
         )
 
+    @classmethod
+    def _checkpoint_payload_match(
+            cls,
+            db: Session,
+            checkpoint_payload: dict[str, Any],
+    ) -> ColumnElement[bool]:
+        """构造跨数据库的冻结计划匹配条件。"""
+        if db.get_bind(mapper=cls).dialect.name == "postgresql":
+            return sql_cast(cls.checkpoint_payload, JSONB) == sql_cast(
+                checkpoint_payload,
+                JSONB,
+            )
+        return cls.checkpoint_payload == checkpoint_payload
+
     @classmethod
     def defer_execution(
             cls,

tests/test_transfer_execution_persistence.py

@@ -4,8 +4,9 @@ from dataclasses import replace
 from datetime import datetime, timezone
 
 import pytest
-from sqlalchemy import create_engine, select
-from sqlalchemy.orm import sessionmaker
+from sqlalchemy import create_engine, create_mock_engine, select
+from sqlalchemy.dialects import postgresql
+from sqlalchemy.orm import Session, sessionmaker
 
 from app.application.transfer.execution import (
     TransferExecutionCheckpoint,
@@ -337,6 +338,46 @@ def test_stage_execution_running_cas_binds_exact_plan_identity(execution_store):
         assert current == 1
 
 
+def test_stage_execution_running_casts_postgresql_json_before_comparison(
+        monkeypatch,
+):
+    """PostgreSQL 的 JSON 计划比较必须转为 JSONB，避免缺少 json 等值操作符。"""
+    engine = create_mock_engine(
+        "postgresql+psycopg://",
+        lambda *_args, **_kwargs: None,
+    )
+    statements = []
+
+    def capture_statement(_db, statement, execution_options=None):
+        """捕获模型生成的 DML，检查生产 PostgreSQL 方言的 SQL。"""
+        del execution_options
+        statements.append(statement)
+        return 1
+
+    monkeypatch.setattr(
+        "app.db.models.transferpending.execute_dml",
+        capture_statement,
+    )
+    payload = {"schema_version": 1, "items": []}
+    with Session(engine) as session:
+        updated = TransferPending.stage_execution_running(
+            session,
+            task_id="task-1",
+            lease_token="lease-1",
+            admission_state="planned",
+            checkpoint_version=1,
+            checkpoint_payload=payload,
+            now_utc="2026-08-27 01:30:00.000000",
+            updated_at="2026-08-27 09:30:00",
+        )
+
+    assert updated == 1
+    assert len(statements) == 1
+    sql = str(statements[0].compile(dialect=postgresql.dialect()))
+    assert "CAST(transferpending.checkpoint_payload AS JSONB)" in sql
+    assert "CAST(%(param_1)s::JSONB AS JSONB)" in sql
+
+
 def test_success_path_persists_steps_and_execution_checkpoint(execution_store):
     """成功路径应保留每步证据，并提交可供唯一 durable writer 结算的检查点。"""
     _seed_pending(execution_store)