The trigram MATCH branch in search_messages() had the same
OperationalError-only catch that #66420 fixed on the main FTS5 branch: a
corrupt messages_fts_trigram shadow table raises the malformed /
'fts5: corrupt structure record' class (sqlite3.DatabaseError, parent of
OperationalError), which propagated straight out of search_messages and
crashed CJK session/history search for read-only sessions.
Route that class through the shared one-shot _try_runtime_fts_rebuild()
and retry the trigram query (catch moved outside self._lock so
rebuild_fts() can re-acquire it, mirroring the main branch). If the
rebuild is refused (guard consumed / FTS disabled / different error) or
the retry fails, fall through to the existing LIKE substring fallback —
which reads only the canonical messages table — instead of raising, so
CJK search degrades gracefully rather than crashing.
Adds two regression tests: trigram search self-heals in place after
shadow-table corruption (answers from the rebuilt trigram index, not the
LIKE fallback), and degrades to LIKE without raising when the one-shot
rebuild was already consumed.
Follow-up to #66420; refs #66296#66724
Complements #66296 (self-heal on the write path): search_messages()'s main
FTS5 MATCH query caught only sqlite3.OperationalError (a query-syntax error →
return empty). A corrupt FTS index raises the malformed / "fts5: corrupt
structure record" class, which is a sqlite3.DatabaseError — the parent of
OperationalError, so it was NOT caught and propagated straight out of
search_messages, crashing session/history search.
The write path now rebuilds and retries on that class, but a read-only
session (cron/CLI history search, or a search issued before any write) never
triggers a write, so its search stayed broken until the next process restart
ran the offline repair.
Catch the DatabaseError corruption class on the search MATCH read too and
route it through the existing one-shot _try_runtime_fts_rebuild(), then retry
the query. The catch is moved outside `with self._lock` so rebuild_fts() can
re-acquire the lock (mirrors _execute_write). The one-shot guard is shared
with the write path, so a single instance never loops on a genuinely
unrecoverable index. OperationalError syntax handling is unchanged (caught
first).
Adds a regression test: with a corrupted messages_fts and no post-corruption
write, search_messages() rebuilds in place and returns the match; without the
fix it raises DatabaseError.
Complements the #65637 salvage (53d358838 + a9cc17fd8): the gateway
session store now retries transcript appends through its own queue, but
cron and CLI writers call SessionDB directly — a corrupt FTS index still
hard-failed their appends until the next process restart triggered the
offline repair.
_execute_write now detects the FTS-corruption error class (both the
generic 'database disk image is malformed' and newer SQLite's
'fts5: corrupt structure record' variant), performs a one-shot in-place
rebuild by delegating to the existing rebuild_fts(), and retries the
failed write. One-shot per instance so an unrecoverable database cannot
loop; lock/busy jitter-retry path untouched.
E2E-verified: corrupted messages_fts_data rejects appends; with this fix
the same append self-heals, persists, and FTS search works again.
