Review follow-ups on #7445 (nesquena-hermes CHANGES_REQUESTED + Greptile).
api/agent_sessions.py
- The read-only pre-aggregated `latest_messages` candidate ordering now
applies to every missing-index projection (default sidebar, gateway
watcher, cron/webhook/kanban views), not only `include_sources ==
("cron",)`. Since the listing no longer self-heals the index, the
correlated `MAX(mx.timestamp)` scan re-ran on every load: 9.86 s on a
5,000-session / 20,000-message DB vs 0.044 s after this change, with
identical selected rows and order. The indexed seek is unchanged.
- `state_db_file_uri()` / `state_db_readonly_uri()` replace
`Path.as_uri()`: a UNC `HERMES_HOME` produced `file://server/share/...`
and CPython's bundled SQLite (3.11-3.13 Windows builds, no
SQLITE_ALLOW_URI_AUTHORITY) rejected the authority, so every agent-backed
session vanished. The builder emits the empty-authority
`file:////server/share/state.db?mode=ro`, keeps `file:///C:/...` for
drive letters, strips `\\?\` / `\\?\UNC\` prefixes, quotes `?`/`#`, and
leaves POSIX output byte-identical. Strict `mode=ro`, no writable
fallback.
scripts/ensure_state_db_read_indexes.py
- `fcntl` / `msvcrt` are imported conditionally; the module imports and
the no-`--lock-file` path runs on native Windows. `--lock-file` uses
`flock` on POSIX, `msvcrt.locking(LK_NBLCK)` on Windows, and fails with
a clear RuntimeError when neither exists. The rw open reuses the
UNC-aware URI builder.
docs/troubleshooting.md
- Operator section: read-only contract, degraded missing-index listing,
drained maintenance prerequisites, lock behaviour, failure modes, UNC.
Tests: tests/test_pr7445_readonly_review_followups.py (19 tests, red
before this change: correlated-subquery plan, missing URI builder,
ImportError on fcntl). Query-plan contract via EXPLAIN QUERY PLAN — no
CORRELATED SCALAR SUBQUERY on missing-index listings, identical rows to
the indexed listing; platform-parametrised URI cases; maintenance module
imported with `sys.modules["fcntl"] = None`. test_issue2628 no longer
pins the cron-only gate; the flock-held test skips without fcntl.
Readers never upgrade to writers. open_state_db_readonly() opens
file:...?mode=ro only; a read-only open failure propagates instead of
silently retrying with a write-capable handle on the multi-GiB WAL
database the agent is streaming into. The session listing no longer
self-heals idx_messages_session with CREATE INDEX (a writer lock held for
minutes on a large messages table) — a missing index degrades to the
pre-aggregated path. Cron sidebar info, insights and deep health checks in
api/routes.py use the same read-only opener.
Watcher (api/gateway_watcher.py): _poll_once returns without touching the
database when nobody is subscribed, and forces a fresh full projection on
the next subscription.
Maintenance (scripts/ensure_state_db_read_indexes.py): the covering read
indexes (idx_messages_session, idx_messages_session_role with NOCASE,
idx_sessions_webui_fingerprint) are created only under --confirm-drained,
optionally holding an exclusive flock on --lock-file for deployments that
serialise agent turns on a lock file; existing indexes are verified for
shape/collation and coverage (EXPLAIN QUERY PLAN), never silently
replaced.
Tests: tests/test_state_db_readonly_readers.py (read-only failure never
retries writable; no poll without subscribers; listing creates no index;
index tool requires drain, is idempotent, works without a lock file and
refuses a held lock; cron sidebar read is mode=ro). Neighbouring tests
that asserted the retired writable fallback / self-heal writer
(test_issue3887_index_prime, test_issue5455_listing_readonly_connection,
test_issue5455_lineage_readonly_reads, test_issue2628_cli_sessions_perf,
test_issue1494_state_db_fd_leak) now assert the read-only contract;
test_issue3506 subscribes before polling.
Anthony Ruiz