perf(state): add messages(session_id, id) index for windowed reads (#76237 salvage) - #76877
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kshitijk4poor merged 1 commit intoAug 2, 2026
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…ueries Every ORDER BY id query on the messages table sorted or scanned the whole session: get_messages_around's window seek, latest_message_row_id (LIMIT 1), and get_messages' full-load ordering all paid O(session history) per call — hot mid-turn via session_search and reactions. messages.id is an original column (INTEGER PRIMARY KEY AUTOINCREMENT), so the index lives in SCHEMA_SQL next to idx_messages_session — no legacy-column migration hazard (the kanban lesson from NousResearch#28776 does not apply). Measured (real schema, one 20k-message session, median of 30): get_messages_around 7.08 -> 0.22 ms (32x), latest_message_row_id 3.37 -> 0.011 ms (307x), get_messages full load 111.6 -> 98.6 ms (1.13x — remaining cost is row deserialization, not the sort). Window results byte-identical at probe points across the session. Tests: VM-step pin (get_messages_around bounded work, calibrated ~12 vs ~855 handler calls, threshold 300 — fails without the index) and window parity with/without the index. No EXPLAIN/plan text (behavior contracts, AGENTS.md).
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Salvage of #76237 by @spfcraze — cherry-picked to preserve authorship. Clean as submitted; no follow-up needed.
Context — what this changes for users
session_search's scroll shape (get_messages_around) — used every time the agent or a user pages through past-conversation context — currently walks the session's whole message history to find the window. On long sessions (thousands of messages) that's a full scan per call. The newmessages(session_id, id)index turns it into an index seek: 32-307x measured, and EXPLAIN-verified (346 VM steps → 2 on the probe workload).Bonus coverage (verified by EXPLAIN probes): the rewind query (
WHERE session_id=? AND id>=?) and last-user-message lookups (ORDER BY id DESC LIMIT 1) also pick up the new index.Review & verification (full pipeline run)
tests/test_hermes_state.pygreen, ruff clean.SCHEMA_SQL(notDEFERRED_INDEX_SQL) is correct —CREATE INDEX IF NOT EXISTSis idempotent for existing DBs.Closes #76237.