Volume title search is an in-memory full scan (~6-7s cold)

[paulyhedral]

GET /volumes/search?q= is slow: 6-7s on a cold query, even for queries that return 0 results.

Evidence (dev, 2026-09-01)

query	latency	bytes
q=c	7.6s	71827
q=cele	7.4s	1183
q=celestialvo (0 results)	6.7s	12
repeat q=celestial	0.9s	1183 (warm)

Cold = full scan; warm is fast only because of WiredTiger cache + the route's CachePage wrapper.

Cause

catalog-data.go data.SearchVolumes (v0.15.0, data/volume.go:417) calls QueryVolumes(ctx, QueryParams{Limit: searchScanLimit}) to pull up to searchScanLimit fully-hydrated volume VOs, then filters in Go with strings.Contains(strings.ToLower(title), needle). Its own doc comment: "scanning the full collection ... in memory rather than pushing the match down to Mongo" (mirrors SearchPersons).

Suggested fix

Push the match to Mongo and cap hydration:

• a title text index, or a normalized title_lower field with a regular index + anchored/prefix regex
• return lightweight {id, title} projections, not full hydrated VOs
• consider the same for SearchPersons and the other entity searches

Mitigation already shipped (frontend)

game-room-web now requires 3 chars and debounces 350ms before calling this endpoint (sweetrpg/game-room-web#434) — cuts the q=c worst case but not the 6s floor.