Adds max_concurrency cap to GlobalRateLimiter using asyncio.Semaphore.
A request now waits for a concurrency slot before the sliding window rate
limit check, so at most N streams are open to the provider simultaneously,
even when the rate window would allow more.
Changes:
- providers/rate_limit.py: max_concurrency param, _concurrency_sem, concurrency_slot() asynccontextmanager
- providers/openai_compat.py: pass max_concurrency to limiter; wrap execute_with_retry + stream iteration in concurrency_slot()
- providers/base.py: max_concurrency field on ProviderConfig
- config/settings.py: provider_max_concurrency setting (PROVIDER_MAX_CONCURRENCY env var, default None = unlimited)
- api/dependencies.py: pass provider_max_concurrency into all three provider ProviderConfig instantiations
- .env.example: document PROVIDER_MAX_CONCURRENCY (commented out)
- tests/providers/test_provider_rate_limit.py: 5 new tests covering concurrency limit enforcement, slot release on exception, noop when unconfigured
- tests/api/test_dependencies.py: add provider_max_concurrency=None to mock settings helper
https://claude.ai/code/session_014mrF1WMNgmNjtPBuoQHsbg
- Create providers/openai_compat.py with shared streaming logic
- Refactor NvidiaNimProvider, OpenRouterProvider, LMStudioProvider to extend it
- OpenRouter overrides _handle_extra_reasoning for reasoning_details
- Update test patches to providers.openai_compat
Co-authored-by: Ali Khokhar <alishahryar2@gmail.com>
