复核 R-b12（直连地址其实还是 PgBouncer、搬断点走了事务模式）：check_pgbouncer 除了没给直连地址，直连地址和应用库地址连的是同一个主机端口（规范化之后比，端口不写按 5432）也拒绝启动，报错说清直连要绕过 PgBouncer；copy-to-postgres 搬断点抽成 checkpoint_conninfo：给了断点库地址用它，否则进目标库、给了直连地址就走直连，命令行加 --direct-url，不给而目标就是应用库时用 AGENTLAB_DATABASE_DIRECT_URL。补测试：同一个主机端口（大小写、用户、参数不同）拒绝、同主机另一个端口放行；搬断点缺省走直连、单给的断点库地址优先、目标是别的库不套用应用库的直连地址

backend/app/db/base.py

@@ -12,6 +12,7 @@ from sqlalchemy import JSON, BigInteger, Column, DateTime, Integer, MetaData, ev
 from sqlalchemy.ext.asyncio import AsyncEngine, AsyncSession, async_sessionmaker, create_async_engine
 from sqlalchemy.orm import DeclarativeBase, Mapped, mapped_column
 from sqlalchemy.pool import NullPool
+from sqlalchemy.engine import make_url
 from sqlalchemy.types import TypeDecorator
 
 from app.core.config import settings
@@ -300,11 +301,26 @@ async def dispose_session_engine() -> None:
 
 
 def check_pgbouncer() -> None:
-    """AGENTLAB_DB_PGBOUNCER=1 却没给直连地址：拒绝启动（事务模式下 LISTEN、会话级咨询锁不成立，跨进程的锁会锁不住、放不掉）。"""
+    """AGENTLAB_DB_PGBOUNCER=1 时直连地址要真的是直连：没给、或者给的和应用库地址指着同一个主机端口（还是那个 PgBouncer），都拒绝
-    if settings.db_pgbouncer and settings.db_dialect == "postgresql" and not settings.database_direct_url:
+    启动（事务模式下 LISTEN、会话级咨询锁不成立，跨进程的锁会锁不住、放不掉；复核 R-b12）。"""
+    if not (settings.db_pgbouncer and settings.db_dialect == "postgresql"):
+        return
+    if not settings.database_direct_url:
         raise RuntimeError("AGENTLAB_DB_PGBOUNCER=1（应用库地址是 PgBouncer 的事务模式）时要另给 AGENTLAB_DATABASE_DIRECT_URL："
                            "进程间通知（LISTEN）、跨进程的锁（会话级咨询锁）、断点库要直连 PostgreSQL（或 PgBouncer 的会话模式）。"
-                           "见 README「用 PostgreSQL」里的三种部署")
+                           "见 README「多进程」里的「直连与 PgBouncer」")
+    if _endpoint(settings.database_direct_url) == _endpoint(settings.database_url):
+        from app.db.urls import describe
+
+        raise RuntimeError(f"AGENTLAB_DATABASE_DIRECT_URL 和 AGENTLAB_DATABASE_URL 指着同一个地址（{describe(settings.database_url)}）："
+                           "AGENTLAB_DB_PGBOUNCER=1 说应用库地址是 PgBouncer 的事务模式，直连地址要绕过它、直接连 PostgreSQL"
+                           "（或者 PgBouncer 的会话模式那个端口）。见 README「多进程」里的「直连与 PgBouncer」")
+
+
+def _endpoint(url: str) -> tuple[str, int]:
+    """地址连的是哪个主机端口（端口不写按 5432）。"""
+    parsed = make_url(url)
+    return (parsed.host or "").lower(), int(parsed.port or 5432)
 
 
 async def get_session() -> AsyncIterator[AsyncSession]:

backend/app/db/to_postgres.py

@@ -481,13 +481,23 @@ async def copy_checkpoints(snapshot_ckpt: Path, conninfo: str, *, dry_run: bool,
 # --------------------------------------------------------------------------
 
 
+def checkpoint_conninfo(target_url: str, *, checkpoint_url: str | None = None, direct_url: str | None = None) -> str:
+    """断点搬到哪儿（psycopg 的连接串）：给了断点库地址用它；否则进目标库——给了直连地址就走直连（复核 R-b12：目标地址是
+    PgBouncer 的事务模式时，psycopg 的预备语句、建表时取的会话级锁都会出问题）。"""
+    if checkpoint_url:
+        return normalize_checkpoint_url(checkpoint_url)
+    return libpq_conninfo(normalize_database_url(direct_url) if direct_url else normalize_database_url(target_url))
+
+
 async def copy_to_postgres(source: str | Path, target_url: str, *, checkpoint_url: str | None = None,
-                           dry_run: bool = False, assume_stopped: bool = False, batch: int = DEFAULT_BATCH,
+                           direct_url: str | None = None, dry_run: bool = False, assume_stopped: bool = False,
-                           work_dir: str | Path | None = None, progress: Callable[[str], None] = print) -> Report:
+                           batch: int = DEFAULT_BATCH, work_dir: str | Path | None = None,
+                           progress: Callable[[str], None] = print) -> Report:
+    """direct_url：目标库的直连地址（目标地址是 PgBouncer 时给；断点走它）。"""
     from app.db.base import create_schema, make_engine
 
     target_url = normalize_database_url(target_url)
-    conninfo = normalize_checkpoint_url(checkpoint_url) if checkpoint_url else libpq_conninfo(target_url)
+    conninfo = checkpoint_conninfo(target_url, checkpoint_url=checkpoint_url, direct_url=direct_url)
     db, ckpt = resolve_source(source)
     if (wal := source_in_use(db, ckpt)) and not assume_stopped:
         raise CopyRefused(f"{wal} 还在：服务看起来还开着这个库。先停服务再导入；确认服务已停（上次是强杀，留下了 "
@@ -567,6 +577,8 @@ def main(argv: list[str] | None = None) -> int:
     parser.add_argument("source", help="数据目录，或者 agentlab.db 的路径（断点库 checkpoints.db 在同一个目录里找）")
     parser.add_argument("target", nargs="?", help="目标地址 postgresql+asyncpg://…；不给就用 AGENTLAB_DATABASE_URL")
     parser.add_argument("--checkpoint-url", help="断点放到另一个 PostgreSQL 库；不给就用 AGENTLAB_CHECKPOINT_URL，再没有就进目标库")
+    parser.add_argument("--direct-url", help="目标库的直连地址（目标地址是 PgBouncer 时给，断点走它）；不给、目标又是 "
+                                             "AGENTLAB_DATABASE_URL 时用 AGENTLAB_DATABASE_DIRECT_URL")
     parser.add_argument("--dry-run", action="store_true", help="只核对：数来源和目标各有多少行，不建表、不写")
     parser.add_argument("--assume-stopped", action="store_true",
                         help="不查服务停没停（来源旁边留着强杀后的 -wal 时用）")
@@ -576,9 +588,16 @@ def main(argv: list[str] | None = None) -> int:
     target = args.target or settings.database_url
     if not target:
         parser.error("没有目标地址：给第二个参数，或者设 AGENTLAB_DATABASE_URL")
+    direct = args.direct_url or None
+    if direct is None and settings.database_direct_url:
+        try:
+            same = normalize_database_url(target) == settings.database_url
+        except ValueError:
+            same = False
+        direct = settings.database_direct_url if same else None
     try:
         report = asyncio.run(copy_to_postgres(
-            args.source, target, checkpoint_url=args.checkpoint_url or settings.checkpoint_url or None,
+            args.source, target, checkpoint_url=args.checkpoint_url or settings.checkpoint_url or None, direct_url=direct,
             dry_run=args.dry_run, assume_stopped=args.assume_stopped, batch=max(args.batch, 1),
             work_dir=args.work_dir))
     except (CopyRefused, ValueError) as e:

backend/tests/test_db_direct.py

@@ -67,3 +67,45 @@ def test_transaction_mode_without_a_direct_url_refuses_to_start(monkeypatch):
     monkeypatch.setattr(settings, "database_direct_url", Settings(database_url=APP, database_direct_url=DIRECT,
                                                                   _env_file=None).database_direct_url)
     base.check_pgbouncer()
+
+
+def test_transaction_mode_with_a_direct_url_that_is_the_same_endpoint_refuses_to_start(monkeypatch):
+    """复核 R-b12：直连地址和应用库地址规范化之后连的是同一个主机端口（还是那个 PgBouncer）——同样拒绝，说清楚。"""
+    from app.db import base
+
+    monkeypatch.setattr(settings, "database_url", Settings(database_url=APP, _env_file=None).database_url)
+    monkeypatch.setattr(settings, "db_pgbouncer", True)
+    for same in (APP, "postgresql+asyncpg://other:pw@PGBOUNCER.internal:6432/agentlab?ssl=require"):
+        monkeypatch.setattr(settings, "database_direct_url",
+                            Settings(database_url=APP, database_direct_url=same, _env_file=None).database_direct_url)
+        with pytest.raises(RuntimeError, match="指着同一个地址"):
+            base.check_pgbouncer()
+    monkeypatch.setattr(settings, "database_direct_url", Settings(
+        database_url=APP, database_direct_url="postgresql://agentlab:secret@pgbouncer.internal:5432/agentlab",
+        _env_file=None).database_direct_url)
+    base.check_pgbouncer()   # 同一台机器上的另一个端口（直连 PostgreSQL 或会话模式）：放行
+
+
+def test_copying_checkpoints_goes_through_the_direct_url(monkeypatch, tmp_path):
+    """复核 R-b12：copy-to-postgres 搬断点缺省走直连地址（设了的话）；单独给了断点库地址就用它。"""
+    from app.db import to_postgres
+
+    assert "db.internal:5432" in to_postgres.checkpoint_conninfo(APP, direct_url=DIRECT)
+    assert "pgbouncer.internal:6432" in to_postgres.checkpoint_conninfo(APP)
+    assert "ckpt.internal" in to_postgres.checkpoint_conninfo(APP, checkpoint_url="postgresql://u:p@ckpt.internal/c",
+                                                              direct_url=DIRECT)
+    seen: dict = {}
+
+    async def fake_copy(source, target, **kw):
+        seen.update(kw, target=target)
+        raise to_postgres.CopyRefused("测试：到这里为止")
+
+    monkeypatch.setattr(to_postgres, "copy_to_postgres", fake_copy)
+    monkeypatch.setattr(settings, "database_url", Settings(database_url=APP, _env_file=None).database_url)
+    monkeypatch.setattr(settings, "database_direct_url",
+                        Settings(database_url=APP, database_direct_url=DIRECT, _env_file=None).database_direct_url)
+    monkeypatch.setattr(settings, "checkpoint_url", "")
+    assert to_postgres.main([str(tmp_path)]) == 2
+    assert seen["direct_url"] == settings.database_direct_url, "目标就是应用库：断点走它的直连地址"
+    assert to_postgres.main([str(tmp_path), "postgresql://u:p@elsewhere.internal:5432/x"]) == 2
+    assert seen["direct_url"] is None, "目标是别的库：不套用应用库的直连地址"