Narrow try_connect except to the retry-eligible error set

ClusterClient.connect's inner try_connect coroutine previously caught
Exception to DEBUG-log each failure and re-raise. That pattern silently
instruments programming bugs (TypeError, AttributeError, …) which are
better left un-wrapped so their tracebacks point at the real source.
Narrow to the transport- and cluster-level types that retry_with_backoff
actually re-attempts: OSError, TimeoutError, DqliteConnectionError,
ClusterError. Matches the _socket_looks_dead / _drain_idle narrowings.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: antoineleclair

src/dqliteclient/cluster.py

@@ -242,7 +242,13 @@ async def try_connect() -> DqliteConnection:
                 )
                 await conn.connect()
                 return conn
-            except Exception as exc:
+            except (OSError, TimeoutError, DqliteConnectionError, ClusterError) as exc:
+                # Narrow catch: these are the transport- and cluster-level
+                # failures the retry loop re-attempts. Anything wider would
+                # silently log-and-re-raise programming bugs (TypeError,
+                # AttributeError, …) which are better left un-instrumented
+                # so the traceback points at the real source. Same pattern
+                # as the _socket_looks_dead / _drain_idle narrowings.
                 logger.debug(
                     "ClusterClient.connect attempt %d/%d failed (leader=%r): %s",
                     attempt,

tests/test_cluster.py

@@ -629,3 +629,21 @@ async def fake_query(_address: str, **_kwargs: object) -> str | None:
         # marker; total upper bound well under the raw 150k.
         assert len(message) < 3_000
         assert "truncated" in message
+
+
+class TestTryConnectNarrowExcept:
+    """Programming bugs (TypeError, AttributeError, …) in the connect
+    path must propagate without being muted by the DEBUG-log instrument.
+    """
+
+    async def test_type_error_propagates(self) -> None:
+        store = MemoryNodeStore(["localhost:9001"])
+        client = ClusterClient(store, timeout=0.1)
+
+        async def fake_find_leader(**_kwargs: object) -> str:
+            raise TypeError("programming bug")
+
+        client.find_leader = fake_find_leader  # type: ignore[method-assign]
+
+        with pytest.raises(TypeError, match="programming bug"):
+            await client.connect(max_attempts=1)