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Long-context downgrade doesn't recognize Claude's '400 You're out of extra usage' and fails instead of retrying at 200k #4065
Description
Summary
On the Claude subscription (Agent SDK) lane, a request that asked for the long-context tier can fail with Claude's generic billing error:
API Error: 400 You're out of extra usage. Add more at claude.ai/settings/usage and keep going.
The long-context downgrade matcher doesn't recognize it. extensions/builtin/anthropic-subscription/errors.ts:114-120 matches only (?:extra usage|usage credits) (?:is|are) required for long context. So instead of retrying at the 200k window, the turn fails, then walks the fallback chain, and the user sees a provider error.
This was seen by a beta user on a build whose engine still appended [1m] to Opus 5/5.5 (#3801, fixed by #3802). After #3802 only legacy ids carry [1m], but any remaining [1m] request (legacy models, or an explicit 1M opt-in) can still hit this.
Expected
When an attempt that requested the long-context tier (a [1m] id) gets this exact 400, it's treated as a long-context refusal: record the refusal and retry once at the 200k window, before visible content, through the same path as the existing refusal (long-context-retry.ts, managed failover). A request that did NOT ask for long context and gets this 400 stays a normal billing failure: no retry, a clear user-facing reason.
Acceptance
- RED with the EXACT error body above: a
[1m]attempt today fails; after the fix it retries at 200k and succeeds (deterministic SDK fake). - The same body on a non-
[1m]attempt does NOT retry. - The existing 'extra usage is required for long context' cases are unchanged.
Related: #3801/#3802, #3751 (refusal wording), #3752, #3753.
Activity
code-yeongyu commentedon Oct 23, 2026
Confirmed with a deterministic Agent SDK fake using the exact response in this issue. On the current base (
f4620f3250), both ambient and managed[1m]attempts stop after one query rather than retrying with the plain model id at 200k.The regression run reported 9 failed, 23 passed across the new issue regression and the existing #3801 request-shape suite. The existing
Extra usage is required for long contextcases still pass. Additional failing assertions cover the explicit billing classification and a failure that persists after the standard-window retry.The fix passes the actual attempt's legacy-window flag to the shared classifier. Both lanes retain their existing pre-visible-content and once-only downgrade path. Requests without
[1m]classify this exact response as non-retryable billing and preserve Claude's actionable reason. GREEN validation and normal commit hooks are queued. Evidence held locally.code-yeongyu commentedon Oct 23, 2026
Implemented in #4066, head
0584156c901654d96bd77341b1409b48f679d461.The exact committed head passed 73 tests in 7 focused files, including both auth lanes, the exact response, standard-window billing controls, the existing refusal wording, visible-content safety, and the retry limit. The changelog gate passed. Normal commit hooks passed the full root static check, and hermetic real-CLI Anthropic mock-loop QA passed 22/22, with zero real provider calls.
The PR remains subject to GitHub CI and formal review. Evidence held locally.
code-yeongyu commentedon Oct 23, 2026
Note: the premise that a
[1m]request is what triggers this billing error is being re-checked from captured requests, since Opus 1M on a subscription should not bill as extra usage. This matcher change (#4066) only affects attempts that explicitly asked for the legacy[1m]tier, but its rationale will be updated once the actual root cause is measured.code-yeongyu commentedon Oct 26, 2026
Linked user report (desktop, 2026.1025.3, Anthropic subscription via OAuth): still failing after reinstall; the desktop provider list also shows an undeletable 'kiro' provider that requests seem to go to (sisyphuslabs/omo-desktop-app#4711). If 'kiro' is a fallback rung in that user's chain, the 'Connection error' shown would be the last rung's failure (this issue's class), not the Claude account's.