docs: add model latency bench notes

docs/test.md

@@ -7,3 +7,16 @@ read_when:
 
 - `pnpm test:force`: Kills any lingering gateway process holding the default control port, then runs the full Vitest suite with an isolated gateway port so server tests don’t collide with a running instance. Use this when a prior gateway run left port 18789 occupied.
 - `pnpm test:coverage`: Runs Vitest with V8 coverage. Global thresholds are 70% lines/branches/functions/statements. Coverage excludes integration-heavy entrypoints (CLI wiring, gateway/telegram bridges, webchat static server) to keep the target focused on unit-testable logic.
+
+## Model latency bench (local keys)
+
+Script: `scripts/bench-model.ts`
+
+Usage:
+- `source ~/.profile && pnpm tsx scripts/bench-model.ts --runs 10`
+- Optional env: `MINIMAX_API_KEY`, `MINIMAX_BASE_URL`, `MINIMAX_MODEL`, `ANTHROPIC_API_KEY`
+- Default prompt: “Reply with a single word: ok. No punctuation or extra text.”
+
+Last run (2025-12-31, 20 runs):
+- minimax median 1279ms (min 1114, max 2431)
+- opus median 2454ms (min 1224, max 3170)