Add opt-in CORS support via PARAKEET_CORS_ORIGINS env var

[arvindvenkataramani]

What this does

Adds configurable CORS support to the FastAPI app. CORS is disabled by default — it only activates when PARAKEET_CORS_ORIGINS is set.

Why

When running this service as part of a larger system (e.g. behind a local dashboard or UI that makes requests from the browser), CORS headers are required. Without them, browser requests are blocked.

I ran into this while integrating parakeet-mlx-fastapi into a custom home automation project. The fix that comes to mind is just allow_origins=["*"], but that's insecure by default — so this adds proper configurability instead.

How to use

Set the PARAKEET_CORS_ORIGINS environment variable to a comma-separated list of allowed origins before starting the server:

PARAKEET_CORS_ORIGINS=http://localhost:3000,https://myapp.example.com parakeet-server

Or in a .env file:

PARAKEET_CORS_ORIGINS=http://localhost:3000

If the variable is unset or empty, no CORSMiddleware is added and the service behaves exactly as before.

Changes

• config.py — reads PARAKEET_CORS_ORIGINS into CORS_ORIGINS: list[str], following the existing PARAKEET_WORKERS pattern
• main.py — imports CORSMiddleware and conditionally adds it in create_app() when CORS_ORIGINS is non-empty

This has been reviewed and tested in a real integration against a local dashboard.