Address findings surfaced by `pre-push-review` after the round 8 sweep:
- Add deck verifier symmetry tests (404, transient 5xx, unexpected
exception, non-numeric metadata) so deck has the same shape as the
notes/news/files verifiers. Also add unexpected-exception tests for
the news and file verifiers, which had `except Exception` branches
no test was reaching. Keeps the registry-style verifier coverage
uniform.
- Modernize sibling field types in `VectorSyncState`, `AppContext`,
and `OAuthAppContext` from `Optional[X]` to `X | None`, matching the
`eviction_task_group: TaskGroup | None` field added in the round 8
diff (resolves the inconsistency flagged by A6). The lone remaining
`Optional` import is dropped.
- Reverse cross-reference direction in the verifier docstrings: the
later-defined `_verify_deck_cards` and `_verify_news_items` now
point at `_verify_notes` as the canonical hoisted-cast pattern,
rather than `_verify_notes` forward-referring to verifiers defined
below it.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
