feat: add per-hop pool references in listener chains

Allow listeners to mix named pools in a single chain using pool:name
syntax. Bare "pool" continues to use the listener's default pool.
Replaces pool_hops field with pool_seq list; pool_hops is now a
backward-compatible property. Each hop draws from its own pool and
failure reporting targets the correct source pool.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

tests/test_api.py

@@ -132,7 +132,7 @@ class TestHandleStatus:
                 ListenerConfig(
                     listen_host="0.0.0.0", listen_port=1081,
                     chain=[ChainHop("socks5", "127.0.0.1", 9050)],
-                    pool_hops=1,
+                    pool_seq=["default"],
                 ),
             ],
         )
@@ -170,6 +170,56 @@ class TestHandleStatusPools:
         assert body["pools"]["mitm"] == {"alive": 3, "total": 8}
 
 
+class TestHandleStatusMultiPool:
+    """Test pool_seq appears in /status only for multi-pool listeners."""
+
+    def test_single_pool_no_pool_seq(self):
+        """Single-pool listener: no pool_seq in response."""
+        config = Config(
+            listeners=[
+                ListenerConfig(
+                    listen_host="0.0.0.0", listen_port=1080,
+                    chain=[ChainHop("socks5", "127.0.0.1", 9050)],
+                    pool_seq=["clean", "clean"], pool_name="clean",
+                ),
+            ],
+        )
+        ctx = _make_ctx(config=config)
+        _, body = _handle_status(ctx)
+        assert "pool_seq" not in body["listeners"][0]
+
+    def test_multi_pool_has_pool_seq(self):
+        """Multi-pool listener: pool_seq appears in response."""
+        config = Config(
+            listeners=[
+                ListenerConfig(
+                    listen_host="0.0.0.0", listen_port=1080,
+                    chain=[ChainHop("socks5", "127.0.0.1", 9050)],
+                    pool_seq=["clean", "mitm"], pool_name="clean",
+                ),
+            ],
+        )
+        ctx = _make_ctx(config=config)
+        _, body = _handle_status(ctx)
+        assert body["listeners"][0]["pool_seq"] == ["clean", "mitm"]
+        assert body["listeners"][0]["pool_hops"] == 2
+
+    def test_multi_pool_in_config(self):
+        """Multi-pool listener: pool_seq appears in /config response."""
+        config = Config(
+            listeners=[
+                ListenerConfig(
+                    listen_host="0.0.0.0", listen_port=1080,
+                    chain=[ChainHop("socks5", "127.0.0.1", 9050)],
+                    pool_seq=["clean", "mitm"], pool_name="clean",
+                ),
+            ],
+        )
+        ctx = _make_ctx(config=config)
+        _, body = _handle_config(ctx)
+        assert body["listeners"][0]["pool_seq"] == ["clean", "mitm"]
+
+
 class TestHandleMetrics:
     """Test GET /metrics handler."""
 
@@ -318,7 +368,7 @@ class TestHandleConfig:
             proxy_pool=pp,
             listeners=[ListenerConfig(
                 chain=[ChainHop("socks5", "127.0.0.1", 9050)],
-                pool_hops=1,
+                pool_seq=["default"],
             )],
         )
         ctx = _make_ctx(config=config)
@@ -345,7 +395,7 @@ class TestHandleConfig:
             listeners=[ListenerConfig(
                 listen_host="0.0.0.0", listen_port=1080,
                 chain=[ChainHop("socks5", "127.0.0.1", 9050)],
-                pool_hops=2, pool_name="clean",
+                pool_seq=["clean", "clean"], pool_name="clean",
             )],
         )
         ctx = _make_ctx(config=config)