Anthropic "Extra usage is required for long context requests" causes infinite retries

[brendandebeasi]

Bug description

When Anthropic returns the error "Extra usage is required for long context requests" (billing tier context limit), opencode classifies it as a retryable API error and retries indefinitely with exponential backoff (observed up to attempt #7 with 2-minute delays).

This error means the prompt exceeds the user's billing tier context window — retrying will never succeed. The correct behavior is to treat it as a context overflow and trigger compaction.

Steps to reproduce

1. Use an Anthropic API key on a billing tier with a standard context limit
2. Have a session grow large enough that the prompt exceeds the tier's context window
3. Observe: Extra usage is required for long context requests. [retrying in 2m attempt #7]

Expected behavior

The error should be classified as context_overflow (same as "prompt is too long"), triggering compaction to reduce context size.

Actual behavior

Classified as a retryable API error. Retries indefinitely, never compacts, and can corrupt session message state from repeated partial writes.

Environment

• opencode version: v1.3.0 / custom-build
• Provider: Anthropic
• OS: macOS

[github-actions]

This issue might be a duplicate of existing issues. Please check:

• "Extra usage is required for long context requests" error still occurs after Anthropic removed long-context premium (March 13) #18242: Same error message ("Extra usage is required for long context requests") causing infinite retry loop — nearly identical report, also discusses the issue from a different angle (Anthropic removing the restriction)
• [Bug]: Session processor retries indefinitely with unbounded exponential backoff — no max retries or circuit breaker #17648: General infinite retry / unbounded exponential backoff bug in the session processor, which is the underlying root cause affecting this scenario as well

Please review these issues and consider whether this can be addressed there, or if this report adds new context worth tracking separately.