diff --git a/tests/test_svc.py b/tests/test_svc.py
index da2e34df..e11433fe 100644
--- a/tests/test_svc.py
+++ b/tests/test_svc.py
@@ -296,12 +296,14 @@ class SvcDbRecoveryTests(unittest.TestCase):
     # ---- 1. 存量 exec= DSN：连续启动两次均恢复，进程参数无秘密 ----
 
     def test_legacy_exec_dsn_survives_consecutive_restarts(self):
-        self.register_pg("pg1", 18890, password="legacy-pw-1")
-        dsn = "postgresql://agent:legacy-pw-1@127.0.0.1:18890/agent"
+        pg_port = free_test_port()
+        self.register_pg("pg1", pg_port, password="legacy-pw-1")
+        dsn = "postgresql://agent:legacy-pw-1@127.0.0.1:%d/agent" % pg_port
         d = self.runtime("dev")
-        self.seed_agent("dev", 18791,
-                        "--addr 127.0.0.1:18791 --data %s --plugins %s --auth auto --dsn %s"
-                        % (d / "data", d / "plugins", dsn))
+        port = free_test_port()
+        self.seed_agent("dev", port,
+                        "--addr 127.0.0.1:%d --data %s --plugins %s --auth auto --dsn %s"
+                        % (port, d / "data", d / "plugins", dsn))
         for _ in range(2):
             self.clear_serve_record()
             self.svc("dev", "restart")
@@ -322,12 +324,14 @@ class SvcDbRecoveryTests(unittest.TestCase):
     # ---- 2. 仅 dbref：裸 restart 与重新部署均保留绑定 ----
 
     def test_dbref_binding_survives_bare_restart_and_redeploy(self):
-        self.register_pg("pg1", 18891, password="bind-pw-2")
-        dsn = "postgresql://agent:bind-pw-2@127.0.0.1:18891/agent"
+        pg_port = free_test_port()
+        self.register_pg("pg1", pg_port, password="bind-pw-2")
+        dsn = "postgresql://agent:bind-pw-2@127.0.0.1:%d/agent" % pg_port
         d = self.runtime("dev")
-        self.seed_agent("dev", 18792,
-                        "--addr 127.0.0.1:18792 --data %s --plugins %s --auth auto"
-                        % (d / "data", d / "plugins"),
+        port = free_test_port()
+        self.seed_agent("dev", port,
+                        "--addr 127.0.0.1:%d --data %s --plugins %s --auth auto"
+                        % (port, d / "data", d / "plugins"),
                         extra_rows=[("dbref", "pg1/agent"), ("db", "pg")])
         self.clear_serve_record()
         self.svc("dev", "restart")
@@ -413,9 +417,10 @@ class SvcDbRecoveryTests(unittest.TestCase):
 
     def test_refusals_keep_registration_without_sqlite_fallback(self):
         d = self.runtime("a1")
-        self.seed_agent("a1", 18796,
-                        "--addr 127.0.0.1:18796 --data %s --plugins %s --auth auto"
-                        % (d / "data", d / "plugins"),
+        port = free_test_port()
+        self.seed_agent("a1", port,
+                        "--addr 127.0.0.1:%d --data %s --plugins %s --auth auto"
+                        % (port, d / "data", d / "plugins"),
                         extra_rows=[("dbref", "pgmissing/agent"), ("db", "pg")])
         self.clear_serve_record()
         result = self.svc("a1", "restart", check=False)
@@ -425,33 +430,41 @@ class SvcDbRecoveryTests(unittest.TestCase):
         self.assertEqual(self.kv("a1", "dbref"), "pgmissing/agent")  # 可恢复配置保留
 
         # 实例登记不全（缺 password）→ 拒启。
-        self.register_pg("pginc", 18895, complete=False)
+        self.register_pg("pginc", free_test_port(), complete=False)
         d = self.runtime("a2")
-        self.seed_agent("a2", 18797,
-                        "--addr 127.0.0.1:18797 --data %s --plugins %s --auth auto"
-                        % (d / "data", d / "plugins"),
+        port = free_test_port()
+        self.seed_agent("a2", port,
+                        "--addr 127.0.0.1:%d --data %s --plugins %s --auth auto"
+                        % (port, d / "data", d / "plugins"),
                         extra_rows=[("dbref", "pginc/agent"), ("db", "pg")])
         result = self.svc("a2", "restart", check=False)
         self.assertNotEqual(result.returncode, 0)
         self.assertIn("拒绝", result.stdout)
 
         # dbref 与 dsn= 指向不同库 → 配置冲突拒启。
-        self.register_pg("pg1", 18896, password="clash-pw")
+        pg_port = free_test_port()
+        self.register_pg("pg1", pg_port, password="clash-pw")
+        other_pg_port = free_test_port()
+        while other_pg_port == pg_port:
+            other_pg_port = free_test_port()
         d = self.runtime("a3")
-        self.seed_agent("a3", 18798,
-                        "--addr 127.0.0.1:18798 --data %s --plugins %s --auth auto"
-                        % (d / "data", d / "plugins"),
+        port = free_test_port()
+        self.seed_agent("a3", port,
+                        "--addr 127.0.0.1:%d --data %s --plugins %s --auth auto"
+                        % (port, d / "data", d / "plugins"),
                         extra_rows=[("dbref", "pg1/agent"), ("db", "pg"),
-                                    ("dsn", "postgresql://u:p@127.0.0.1:18999/otherdb")])
+                                    ("dsn", "postgresql://u:p@127.0.0.1:%d/otherdb"
+                                     % other_pg_port)])
         result = self.svc("a3", "restart", check=False)
         self.assertNotEqual(result.returncode, 0)
         self.assertIn("拒绝", result.stdout)
 
         # db=pg 但无可恢复 DSN → 拒启。
         d = self.runtime("a4")
-        self.seed_agent("a4", 18799,
-                        "--addr 127.0.0.1:18799 --data %s --plugins %s --auth auto"
-                        % (d / "data", d / "plugins"),
+        port = free_test_port()
+        self.seed_agent("a4", port,
+                        "--addr 127.0.0.1:%d --data %s --plugins %s --auth auto"
+                        % (port, d / "data", d / "plugins"),
                         extra_rows=[("db", "pg")])
         result = self.svc("a4", "restart", check=False)
         self.assertNotEqual(result.returncode, 0)