* fix(sidebar): prime idx_messages_session before CLI-session scan (#3887)
The sidebar's CLI-session scan (read_importable_agent_session_rows) orders
candidate sessions by a correlated MAX(timestamp) subquery over messages,
which collapses to a full per-session table scan when the agent's standard
idx_messages_session ON messages(session_id, timestamp) index is absent.
A normally-migrated hermes-agent state.db has it; a db that lost its
migrations (older hermes-agent, or a hand-rebuilt/reimported db) does not,
and /api/sessions then stalls for seconds on every refresh (the 5s cache
TTL never settles -> repeating 'Slow WebUI request still running' warnings).
Prime the index with CREATE INDEX IF NOT EXISTS before the scan: a no-op
when it already exists, a ~20ms self-heal otherwise (measured 13.3s ->
0.009s on a no-index 8k-session db). Best-effort: degrades silently on a
read-only db, a locked db, or a minimal schema without a timestamp column.
Closes#3887
* test(#3887): skip read-only-db test under root (greptile P2)
Root bypasses POSIX permission bits, so chmod 0444 doesn't make the file
read-only for root — the prime would succeed and the test would validate the
wrong path, giving false confidence on root-run CI. Skip under root; the
production handler's except sqlite3.Error: pass covers the read-only/locked/
corrupted/older-schema cases regardless.
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Co-authored-by: nesquena-hermes <[email protected]>
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