fix(heartbeat): replace bare except Exception with specific types and intent comments

decnet/web/router/swarm/api_heartbeat.py

@@ -19,7 +19,7 @@ from datetime import datetime, timezone
 from typing import Any, Optional
 
 from fastapi import APIRouter, Depends, HTTPException, Request
-from pydantic import BaseModel
+from pydantic import BaseModel, ValidationError
 
 from decnet.config import DeckyConfig
 from decnet.logging import get_logger
@@ -60,7 +60,8 @@ def _extract_peer_fingerprint(scope: dict[str, Any]) -> Optional[str]:
         if chain:
             peer_der = chain[0]
             source = "primary"
-    except Exception:
+    except (AttributeError, KeyError, TypeError):
+        # scope["extensions"]["tls"] structure varies across uvicorn versions
         peer_der = None
 
     if peer_der is None:
@@ -71,7 +72,8 @@ def _extract_peer_fingerprint(scope: dict[str, Any]) -> Optional[str]:
                 peer_der = ssl_obj.getpeercert(binary_form=True)
                 if peer_der:
                     source = "fallback"
-        except Exception:
+        except (AttributeError, OSError):
+            # transport may not be an SSL transport, or the handshake may be incomplete
             peer_der = None
 
     if not peer_der:
@@ -121,6 +123,7 @@ async def _reconcile_topology_report(
     try:
         topos = await repo.list_topologies(status=TopologyStatus.ACTIVE)
     except Exception:
+        # Non-fatal: reconcile is best-effort; the host stays alive regardless
         log.exception("heartbeat: could not list active topologies")
         return
     mine = [t for t in topos if t.get("target_host_uuid") == host_uuid]
@@ -139,6 +142,7 @@ async def _reconcile_topology_report(
             try:
                 hydrated = await hydrate(repo, tid)
             except Exception:
+                # Non-fatal: skip this topology; mutator reconcile loop will retry
                 log.exception("heartbeat: hydrate failed tid=%s", tid)
                 continue
             if hydrated is None:
@@ -155,6 +159,7 @@ async def _reconcile_topology_report(
                 tid, host_uuid, reported_id, reported_hash, expected,
             )
         except Exception:
+            # Non-fatal: mutator reconcile loop will detect the mismatch again next heartbeat
             log.exception("heartbeat: failed to flag resync tid=%s", tid)
 
 
@@ -192,7 +197,7 @@ async def heartbeat(
     for decky_dict in status_body.get("deckies") or []:
         try:
             d = DeckyConfig(**decky_dict)
-        except Exception:
+        except (ValidationError, TypeError):
             log.exception("heartbeat: skipping malformed decky payload host=%s", req.host_uuid)
             continue
         rstate = runtime.get(d.name) or {}