[Bug]: A Muse turn stopped by the subscription quota shows as a provider error, not Limited #18236

Before submitting

• I searched existing issues and did not find a duplicate.
• I included enough detail to reproduce or investigate the problem.

Area

apps/server

Steps to reproduce

A real run needs a used-up Meta subscription window. To reproduce on demand I put a small proxy between Muse and api.meta.ai (Muse's endpoint_transport setting) that answers POST /v1/responses with HTTP 429 and the body Meta sends for a used-up window:

{"error": {"code": "rate_limit_exceeded", "message": "Subscription quota exhausted. Your usage window resets soon.", "resets_at": 1791730859, "type": "rate_limit_error"}}

1. Enable the Muse Code provider on a host signed in to a Meta subscription.
2. Send a Muse thread a message while the quota is used up (or the proxy refuses it).

Expected behavior

The thread is marked Limited, with Resume at reset and Snooze until reset, the way a Codex or Claude turn that hits its limit is. "Auto-resume limited threads" then works for Muse too.

Actual behavior

Muse treats the refusal as a quota stop (error_kind: tier_limit, not retried) and fails the turn with API error 429: Subscription quota exhausted. Your usage window resets soon. (rate_limit_error). T3 shows that as a red "Provider error" and marks the thread Failed, with no reset time and no way to resume at reset. The adapter maps every failed turn to provider_error or transport_error (adapter.ts). Muse also drops the resets_at Meta sends with the refusal.

Impact

Minor bug or occasional failure

Version or commit

main @ ed0f7b9

Environment

Linux (Ubuntu 24.04), web client in Chromium, Node 24.21.0, Muse Code 1.4.4 (1.4.4-R5419.1), muse-spark-1.3-contributor on a Meta subscription

Logs or stack traces

# muse exec --json against the same proxy (Muse 1.4.4), trimmed
task.lifecycle.status  phase=stream_failed  error_kind=tier_limit  http_status=429  "failed meta model stream attempt 1/10"
run.terminal.failed    reason="API error 429: Subscription quota exhausted. Your usage window resets soon. (rate_limit_error)"

Screenshots, recordings, or supporting files

The refused turn and the thread's status on main:

Workaround

Wait for the window to reset and send the message again by hand.

Proposed fix

In packages/provider-muse's adapter, when a failed turn's message is Muse's quota refusal (API error 429 with "Subscription quota" or "usage limit"), report it as a usage_limit failure titled "Usage limit reached" instead of provider_error. Its resetAt comes from the newest usage/changed report Muse sent before the refusal: the latest reset among the windows that report showed used up. If no report showed a used-up window, the thread is still Limited, without a reset time. The change includes focused tests for the classification and the reset time, and before/after screenshots on web and mobile.

A working version of this was part of #17151, which was closed for missing screenshots. Once this is triaged I'll open a focused PR for it.

Filed with Claude Opus 5.5 in Claude Code.