feat: named proxy pools with per-listener assignment

Add proxy_pools: top-level config (dict of name -> pool config) so
listeners can draw from different proxy sources. Each pool has
independent sources, health testing, state persistence, and refresh
cycles.

- PoolSourceConfig gains mitm: bool|None for API ?mitm=0/1 filtering
- ListenerConfig gains pool_name for named pool assignment
- ProxyPool gains name param with prefixed log messages and
  per-name state file derivation (pool-{name}.json)
- server.py replaces single proxy_pool with proxy_pools dict,
  validates listener pool references at startup, per-listener closure
- API /pool merges all pools (with pool field on multi-pool entries),
  /status and /config expose per-pool summaries
- Backward compat: singular proxy_pool: registers as "default"

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

tests/test_pool.py

@@ -11,6 +11,95 @@ from s5p.config import ChainHop, PoolSourceConfig, ProxyPoolConfig
 from s5p.pool import ProxyEntry, ProxyPool
 
 
+class TestProxyPoolName:
+    """Test pool name and state path derivation."""
+
+    def test_default_name(self):
+        cfg = ProxyPoolConfig(sources=[])
+        pool = ProxyPool(cfg, [], timeout=10.0)
+        assert pool.name == "default"
+        assert pool._log_prefix == "pool"
+
+    def test_named_pool(self):
+        cfg = ProxyPoolConfig(sources=[])
+        pool = ProxyPool(cfg, [], timeout=10.0, name="clean")
+        assert pool.name == "clean"
+        assert pool._log_prefix == "pool[clean]"
+
+    def test_state_path_default(self):
+        cfg = ProxyPoolConfig(sources=[])
+        pool = ProxyPool(cfg, [], timeout=10.0)
+        assert pool._state_path.name == "pool.json"
+
+    def test_state_path_named(self):
+        cfg = ProxyPoolConfig(sources=[])
+        pool = ProxyPool(cfg, [], timeout=10.0, name="clean")
+        assert pool._state_path.name == "pool-clean.json"
+
+    def test_state_path_explicit_overrides_name(self):
+        cfg = ProxyPoolConfig(sources=[], state_file="/data/custom.json")
+        pool = ProxyPool(cfg, [], timeout=10.0, name="clean")
+        assert str(pool._state_path) == "/data/custom.json"
+
+
+class TestProxyPoolMitmQuery:
+    """Test mitm query parameter in API fetch."""
+
+    def test_mitm_false(self):
+        cfg = ProxyPoolConfig(sources=[])
+        pool = ProxyPool(cfg, [], timeout=10.0)
+        src = PoolSourceConfig(url="http://api:8081/proxies/all", mitm=False)
+
+        async def run():
+            from unittest.mock import AsyncMock, patch
+            mock_ret = {"proxies": []}
+            with patch(
+                "s5p.pool.http_get_json",
+                new_callable=AsyncMock, return_value=mock_ret,
+            ) as mock:
+                await pool._fetch_api(src)
+                call_url = mock.call_args[0][0]
+                assert "mitm=0" in call_url
+
+        asyncio.run(run())
+
+    def test_mitm_true(self):
+        cfg = ProxyPoolConfig(sources=[])
+        pool = ProxyPool(cfg, [], timeout=10.0)
+        src = PoolSourceConfig(url="http://api:8081/proxies/all", mitm=True)
+
+        async def run():
+            from unittest.mock import AsyncMock, patch
+            mock_ret = {"proxies": []}
+            with patch(
+                "s5p.pool.http_get_json",
+                new_callable=AsyncMock, return_value=mock_ret,
+            ) as mock:
+                await pool._fetch_api(src)
+                call_url = mock.call_args[0][0]
+                assert "mitm=1" in call_url
+
+        asyncio.run(run())
+
+    def test_mitm_none_omitted(self):
+        cfg = ProxyPoolConfig(sources=[])
+        pool = ProxyPool(cfg, [], timeout=10.0)
+        src = PoolSourceConfig(url="http://api:8081/proxies/all", mitm=None)
+
+        async def run():
+            from unittest.mock import AsyncMock, patch
+            mock_ret = {"proxies": []}
+            with patch(
+                "s5p.pool.http_get_json",
+                new_callable=AsyncMock, return_value=mock_ret,
+            ) as mock:
+                await pool._fetch_api(src)
+                call_url = mock.call_args[0][0]
+                assert "mitm" not in call_url
+
+        asyncio.run(run())
+
+
 class TestProxyEntry:
     """Test ProxyEntry defaults."""