Previously getRateLimitResetDelayMs only read the Anthropic-specific
'anthropic-ratelimit-unified-reset' header (Unix timestamp), returning
null for every other provider. This meant OpenAI, GitHub, and Codex
users in persistent retry mode (CLAUDE_CODE_UNATTENDED_RETRY=1) always
fell back to dumb exponential backoff even when the server included an
exact reset time in the response headers.
This change makes the function provider-aware:
- firstParty (Anthropic): existing behaviour preserved — reads
'anthropic-ratelimit-unified-reset' Unix timestamp
- openai / codex / github: reads 'x-ratelimit-reset-requests' and
'x-ratelimit-reset-tokens' (OpenAI relative duration strings like
"1s", "6m0s", "1h30m0s"), picks the larger of the two so retries
don't fire before both token and request limits have reset
- bedrock / vertex / foundry / gemini: returns null (no standard
reset header for these providers)
Adds parseOpenAIDuration() as an exported helper to convert OpenAI's
duration format into milliseconds.
16 new tests covering all provider paths and edge cases.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
