refactor: rename exception variable from exc to exception (leanEthereum#803)

Expands the `exc` abbreviation used in `except X as exc:` clauses to
the full word `exception`, matching the no-abbreviations rule in
CLAUDE.md. Adds the rule explicitly so future code keeps the full
spelling.

Co-authored-by: Claude Opus 4.7 <noreply@anthropic.com>

Author: tcoratger

CLAUDE.md

@@ -40,6 +40,8 @@ subspecifications that the Lean Ethereum protocol relies on.
     - `prop` → `proposal`, `conn` → `connection`, `addr` → `address`, `cert` → `certificate`
     - `privkey` → `private_key`, `elem` → `element`, `buf` → `buffer`, `dir` → `directory`
     - `len` → `length` (inside a name, never the `len()` builtin), `fe` → `field_elements`
+    - `exc` / `e` → `exception` (in `except X as exc:` clauses, use `exception`; the stdlib
+      `exc_info` name is still kept verbatim)
   - Use the correct domain term, not just any expansion: a validator is referenced by its
     INDEX, so `validator_id` → `validator_index` (never `validator_id`).
   - KEEP canonical protocol identifiers that genuinely use "ID": `peer_id`, `node_id`,

packages/testing/src/consensus_testing/test_fixtures/networking_codec.py

@@ -144,8 +144,8 @@ def _make_decode_failure(self) -> dict[str, Any]:
         exception_raised: Exception | None = None
         try:
             decoder(raw)
-        except Exception as exc:
-            exception_raised = exc
+        except Exception as exception:
+            exception_raised = exception
 
         if exception_raised is None:
             raise AssertionError(

packages/testing/src/consensus_testing/test_fixtures/ssz.py

@@ -121,8 +121,8 @@ def _make_decode_failure(self) -> "SSZTest":
         exception_raised: Exception | None = None
         try:
             decoder.decode_bytes(raw)
-        except Exception as exc:
-            exception_raised = exc
+        except Exception as exception:
+            exception_raised = exception
 
         if exception_raised is None:
             raise AssertionError(

packages/testing/src/consensus_testing/test_fixtures/verify_proofs.py

@@ -155,8 +155,8 @@ def make_fixture(self) -> VerifyProofsTest:
         # a comparable "expected X got Y" message instead of crashing the filler.
         try:
             candidate.verify(public_keys, message, slot)
-        except Exception as exc:
-            exception_raised = exc
+        except Exception as exception:
+            exception_raised = exception
 
         if self.expect_exception is None:
             if exception_raised is not None:

src/lean_spec/cli/bootstrap.py

@@ -118,11 +118,11 @@ def from_cli_args(cls, args: CliArgs) -> NodeBootstrap:
                     for s in args.aggregate_subnet_ids_raw.split(",")
                     if s.strip()
                 )
-            except ValueError as exc:
+            except ValueError as exception:
                 raise CliValidationError(
                     "--aggregate-subnet-ids expects comma-separated integers, "
                     f"got {args.aggregate_subnet_ids_raw!r}"
-                ) from exc
+                ) from exception
 
         # Genesis load.
         logger.info("Loading genesis from %s", args.genesis_path)

src/lean_spec/cli/main.py

@@ -27,8 +27,8 @@ def main() -> None:
     # Validate cross-field rules and load referenced files.
     try:
         boot = NodeBootstrap.from_cli_args(args)
-    except (CliValidationError, FileNotFoundError) as exc:
-        logger.error("%s", exc)
+    except (CliValidationError, FileNotFoundError) as exception:
+        logger.error("%s", exception)
         sys.exit(1)
 
     # Run the node under an event loop until shutdown or a fatal error.

src/lean_spec/node/api/endpoints/aggregator.py

@@ -58,8 +58,8 @@ async def handle_toggle(request: web.Request) -> web.Response:
 
     try:
         payload = await request.json()
-    except json.JSONDecodeError as exc:
-        raise web.HTTPBadRequest(reason="Invalid JSON body") from exc
+    except json.JSONDecodeError as exception:
+        raise web.HTTPBadRequest(reason="Invalid JSON body") from exception
 
     if not isinstance(payload, dict) or "enabled" not in payload:
         raise web.HTTPBadRequest(reason="Missing 'enabled' field in body")

src/lean_spec/node/networking/client/event_source/live.py

@@ -424,8 +424,8 @@ async def start_serving(
             logger.info("Connecting to bootnode %s", multiaddr)
             try:
                 peer_id = await self.dial(multiaddr)
-            except Exception as exc:
-                logger.warning("Failed to connect to bootnode %s: %s", multiaddr, exc)
+            except Exception as exception:
+                logger.warning("Failed to connect to bootnode %s: %s", multiaddr, exception)
                 continue
             if peer_id is not None:
                 logger.info("Connected to bootnode, peer_id=%s", peer_id)

src/lean_spec/node/sync/checkpoint_sync.py

@@ -90,14 +90,14 @@ async def fetch_finalized_state(url: str, state_class: type[State]) -> State:
 
             return state
 
-    except httpx.RequestError as exc:
+    except httpx.RequestError as exception:
         raise CheckpointSyncError(
-            f"Network error while connecting to {exc.request.url}: {exc}"
-        ) from exc
-    except httpx.HTTPStatusError as exc:
+            f"Network error while connecting to {exception.request.url}: {exception}"
+        ) from exception
+    except httpx.HTTPStatusError as exception:
         raise CheckpointSyncError(
-            f"HTTP error {exc.response.status_code}: {exc.response.text[:200]}"
-        ) from exc
+            f"HTTP error {exception.response.status_code}: {exception.response.text[:200]}"
+        ) from exception
     except Exception as e:
         raise CheckpointSyncError(f"Failed to fetch state: {e}") from e
 

src/lean_spec/node/sync/head_sync.py

@@ -310,10 +310,10 @@ async def _process_cached_descendants(
                     )
                     processed_count += description_count
 
-                except Exception as exc:
+                except Exception as exception:
                     # Processing failed. Leave in cache for retry or discard.
                     # Do not cascade the error; continue with other children.
-                    logger.debug("Failed to process cached descendant: %s", exc)
+                    logger.debug("Failed to process cached descendant: %s", exception)
 
             finally:
                 self._processing.discard(child_root)