Two gate-found CORE/SILENT edges fixed on-branch:
- api/config.py: switching the main default to a different custom:* provider kept
the OLD provider's base_url, routing New Chat to the wrong endpoint. The
base_url-clear on provider-change now covers custom:* too (was exempted).
- static/sessions.js: newSession() skipped the configured default when S.session
was null but the picker held stale state (e.g. after deleting the last session),
inheriting the stale model. Default now wins over legacy picker regardless of
loaded-session state (explicit empty-composer override still takes priority).
- Updated 2 stale source-grep precedence assertions + widened a brittle 6000-char
newSession() slice window to 7000 (assignment block grew; intent unchanged).
- 2 new non-vacuous regression tests (custom base_url clear; precedence).
Co-authored-by: Rod Boev <rod.boev@gmail.com>
The pre-session toolset comment pushed the #2518 provenance comment past the
test_issue2518 4000-char window assertion. Trim the comment to one line and
widen the test window to 5000 (the fallback block it actually guards is well
within range; newSession() has legitimately grown).
## Release v0.51.238 — Release HF (stage-q9)
Phase 3 MEDIUM-ring pick (3-factor: contributor×impact×mitigated-risk) — high-impact perf fix to the most-clicked affordance from a regular contributor (@franksong2702 ★★★), small code surface, CI-green.
### Fixed
| PR | Author | Fix |
|----|--------|-----|
| #2518 follow-up | @franksong2702 | Clicking **New Conversation** on a cold start no longer hangs 3–4s on a catalog rebuild. `newSession()` fills `model_provider` from `window._activeProvider` (then prev-session) when the dropdown carries none, so `POST /api/session/new` takes the fast path on the first click too. |
### Pre-release dual gate caught a wrong-backend routing bug (fixed + regression-tested)
The server fast path passes `(model, provider)` through **without validating the pair**, so naively attaching the active provider to *any* bare model could silently route to the wrong backend (e.g. bare `claude-opus-4.8` + active `openrouter`). **Codex** flagged this; **Opus** had judged it acceptable ("respect the selection over silent swap"). I took the stricter, empirically-grounded path and added a **family-mismatch guard** mirroring the server's own bare-prefix→provider map (`gpt`→openai, `claude`→anthropic, `gemini`→google): when the model's known family differs from the fallback provider, `model_provider` stays `null` so the server slow-path's family repair runs. This keeps the perf win for the common matching case while closing the mis-route. Backend behavioral tests confirm fast-path-on-match + slow-path-on-mismatch. (Also re-anchored the source-shape test assertions on the real `reqBody.model_provider=` assignment per Codex's 2nd note.)
### Gate results
- **Full pytest suite**: 7495 passed, 9 skipped, 3 xpassed, **0 failed**
- **ESLint runtime gate**: CLEAN · **ruff**: CLEAN · **browser-smoke**: CLEAN
- **Codex (regression)**: SHIP ONLY WITH FIXES → guard + test-anchor applied → re-reviewed **SAFE TO SHIP**
- **Opus (correctness)**: reviewed the original (judged acceptable); the shipped version is strictly safer (adds the family guard)
Note: `docs/pr-media/2518/{PR_BODY.md,bench.py}` are the contributor's review aids, included per the tracked `docs/pr-media/` convention (157 files already tracked) — not app code.
Closes#2518.
Co-authored-by: franksong2702 <franksong2702@users.noreply.github.com>
