Do not trigger account cooldown or fallback for request-scoped 4xx errors that match no account rules so healthy credentials are not locked out for context length or validation errors.
- Endpoint: per-API-key model allowlist (schema v3) enforced on chat (403)
and /v1/models; Full-access toggle + multi-select picker in Keys UI.
- Providers: honor x-connection-id in /v1/chat/completions — pinned requests
no longer rotate to another account on failure.
- Providers: strategy saves merge into stored enabled:false override;
Test All groups match grid sections; 1-by-1 skips disabled connections.
- Dashboard: provider-card toggle syncs from server on failure; grid toggles
always visible; connection rows get clear-✕ for stale error banners.
- Combo editor: on desktop (xl+) the Add-Model picker opens as a floating
side panel beside the untouched combo popup instead of stacking on top;
mobile keeps the full-screen overlay.
- Long API-key overflow fixed in key rows + provider model sections.
Kiro returns HTTP 400 with 'Improperly formed request (reset after Xs)'
when a model is not available on that account's subscription tier.
Previously this fell through to COOLDOWN_MS.transient (30s), causing
rapid retries on all accounts before failing — all accounts get locked
simultaneously with no actual fallback.
Treating this as paymentRequired (2min cooldown) ensures:
1. The model is locked on that account for 2min (proper cooldown)
2. The next available account is tried immediately
3. If all accounts hit the same 400, 9Router falls through to the
next provider in the combo
Fixes#384
