Postgres real backend: psycopg adapter, schema, migration

Replace the PostgresDatabase skeleton with a real implementation:
psycopg (v3) first, psycopg2 second, lazy load, missing driver
still raises PostgresDriverMissingError with no silent SQLite
fallback. A sqlite3-style adapter (PgConnection/PgCursor/PgRow)
translates ? placeholders to %s outside string literals, maps
UNIQUE/FK violations, lock errors and connection failures to
explicit Postgres error types, and handles INSERT OR REPLACE,
PRAGMA table_info, AUTOINCREMENT and FTS5 refusal. POSTGRES_SCHEMA
covers all business tables with tasks result columns; server
init_db uses it under CLOUD_DB_BACKEND=postgres, SQLite path
unchanged. migrate_sqlite_to_postgres.py copies rows with
ON CONFLICT DO NOTHING and reseeds identity sequences.
Tests: cloud 239 (235 pass, 4 skipped without a real server),
host 27 pass; real-server tests skip unless CLOUD_TEST_PG_DSN
is set.

cloud/tests/test_postgres_integration.py

@@ -0,0 +1,172 @@
+"""Postgres 集成测试：真实服务器上的端到端路径。
+
+全部测试在无真实 Postgres 时 skip，绝不 fail。判定条件与
+test_postgres_backend.py 的 _real_pg_params() 一致：须显式
+设置 CLOUD_TEST_PG_DSN（postgres://user:pass@host:port/dbname）
+且主机端口 2 秒内可达，且装有 psycopg 驱动。DSN 必须指向
+一次性测试库；本文件只写业务表与测试行，跑完删掉测试行，
+不删库、不动其它库。DSN 只从环境变量读，测试不打印它。
+"""
+
+import os
+import sys
+import tempfile
+import unittest
+from pathlib import Path
+
+try:
+    from cloud.tests.test_postgres_backend import (
+        _has_real_driver,
+        _real_pg_params,
+    )
+    from cloud.db import PostgresDatabase, init_postgres_schema
+    from cloud.migrations import migrate_sqlite_to_postgres
+    from cloud.server import init_db
+except ImportError:  # discover -s cloud/tests 时把项目根目录补进 sys.path
+    sys.path.insert(0, str(Path(__file__).resolve().parents[2]))
+    from cloud.tests.test_postgres_backend import (
+        _has_real_driver,
+        _real_pg_params,
+    )
+    from cloud.db import PostgresDatabase, init_postgres_schema
+    from cloud.migrations import migrate_sqlite_to_postgres
+    from cloud.server import init_db
+
+
+def _pg_db_or_skip(testcase):
+    params = _real_pg_params()
+    if params is None:
+        testcase.skipTest("未设置可达的 CLOUD_TEST_PG_DSN，跳过真实 PG 测试")
+    if not _has_real_driver():
+        testcase.skipTest("未装 psycopg 驱动，跳过真实 PG 测试")
+    host, port, dbname, user, password = params
+    return PostgresDatabase(host=host, port=port, dbname=dbname,
+                            user=user, password=password)
+
+
+class PostgresIntegrationTestCase(unittest.TestCase):
+    def test_server_init_db_and_adapter_crud(self):
+        db = _pg_db_or_skip(self)
+        conn = db.connect()
+        try:
+            init_postgres_schema(conn)
+            # 适配层 CRUD：projects 插、读、改、删均走 ? 占位符。
+            with db.transaction(conn):
+                conn.execute(
+                    "INSERT INTO projects(id, name, owner_id, created_at)"
+                    " VALUES(?, ?, ?, ?)",
+                    ("pg-int-proj", "pg-int", "pg-int-user", 0.0))
+            rows = db.read_all(
+                conn, "SELECT * FROM projects WHERE id = ?",
+                ("pg-int-proj",))
+            self.assertEqual(len(rows), 1)
+            self.assertEqual(rows[0]["name"], "pg-int")
+            with db.transaction(conn):
+                conn.execute(
+                    "UPDATE projects SET name = ? WHERE id = ?",
+                    ("pg-int-2", "pg-int-proj"))
+            rows = db.read_all(
+                conn, "SELECT name FROM projects WHERE id = ?",
+                ("pg-int-proj",))
+            self.assertEqual(rows[0]["name"], "pg-int-2")
+        finally:
+            try:
+                with db.transaction(conn):
+                    conn.execute("DELETE FROM projects WHERE id = ?",
+                                 ("pg-int-proj",))
+            except Exception:
+                pass
+            conn.close()
+
+    def test_sqlite_to_postgres_migration_is_idempotent(self):
+        import sqlite3
+        db = _pg_db_or_skip(self)
+        # 先建一个最小 SQLite 库：含 projects/tasks 两行。
+        with tempfile.TemporaryDirectory() as tmp:
+            src = os.path.join(tmp, "src.db")
+            sconn = sqlite3.connect(src)
+            sconn.execute(
+                "CREATE TABLE projects(id TEXT PRIMARY KEY, name TEXT,"
+                " owner_id TEXT, created_at REAL)")
+            sconn.execute(
+                "CREATE TABLE tasks(id TEXT PRIMARY KEY, project_id TEXT,"
+                " prompt TEXT, status TEXT)")
+            sconn.execute(
+                "INSERT INTO projects VALUES(?, ?, ?, ?)",
+                ("mig-proj", "mig", "mig-user", 1.5))
+            sconn.execute(
+                "INSERT INTO tasks VALUES(?, ?, ?, ?)",
+                ("mig-task", "mig-proj", "hello", "queued"))
+            sconn.commit()
+            sconn.close()
+            conn = db.connect()
+            try:
+                first = migrate_sqlite_to_postgres(src, pg_conn=conn)
+                self.assertGreaterEqual(first.get("projects", 0), 1)
+                self.assertGreaterEqual(first.get("tasks", 0), 1)
+                # 第二次跑：ON CONFLICT DO NOTHING，不重复插。
+                second = migrate_sqlite_to_postgres(src, pg_conn=conn)
+                self.assertEqual(second.get("projects", -1), 0)
+                self.assertEqual(second.get("tasks", -1), 0)
+                rows = db.read_all(
+                    conn, "SELECT * FROM projects WHERE id = ?",
+                    ("mig-proj",))
+                self.assertEqual(len(rows), 1)
+                self.assertEqual(rows[0]["name"], "mig")
+            finally:
+                try:
+                    with db.transaction(conn):
+                        conn.execute("DELETE FROM tasks WHERE id = ?",
+                                     ("mig-task",))
+                        conn.execute("DELETE FROM projects WHERE id = ?",
+                                     ("mig-proj",))
+                except Exception:
+                    pass
+                conn.close()
+
+    def test_server_init_db_on_postgres(self):
+        # 真走 server.init_db 的 PG 分支：环境变量切到 postgres
+        # 后，init_db 不应建任何 SQLite 文件，而应在 PG 里建表
+        # （含 tasks 的 6 个结果列）；本测试不启动 HTTP server。
+        import os
+        from unittest import mock
+        params = _real_pg_params()
+        if params is None:
+            self.skipTest("未设置可达的 CLOUD_TEST_PG_DSN，跳过真实 PG 测试")
+        if not _has_real_driver():
+            self.skipTest("未装 psycopg 驱动，跳过真实 PG 测试")
+        host, port, dbname, user, password = params
+        env = {
+            "CLOUD_DB_BACKEND": "postgres",
+            "CLOUD_DB_HOST": host,
+            "CLOUD_DB_PORT": str(port),
+            "CLOUD_DB_NAME": dbname,
+            "CLOUD_DB_USER": user or "",
+            "CLOUD_DB_PASSWORD": password or "",
+        }
+        with mock.patch.dict(os.environ, env):
+            init_db("ignored-in-postgres-mode.db")
+            db = PostgresDatabase(host=host, port=port, dbname=dbname,
+                                  user=user, password=password)
+            conn = db.connect()
+            try:
+                rows = db.read_all(
+                    conn,
+                    "SELECT table_name FROM information_schema.tables"
+                    " WHERE table_schema = 'public'",
+                    ())
+                names = {r["table_name"] for r in rows}
+                self.assertIn("projects", names)
+                self.assertIn("tasks", names)
+                self.assertIn("audit_log", names)
+                cols = db.read_all(
+                    conn,
+                    "SELECT column_name FROM information_schema.columns"
+                    " WHERE table_name = 'tasks'",
+                    ())
+                colnames = {r["column_name"] for r in cols}
+                for col in ("result_text", "error_text", "actual_model",
+                            "started_at", "finished_at", "child_pid"):
+                    self.assertIn(col, colnames)
+            finally:
+                conn.close()