feat(limiter): prune empty keys; fail-safe key_func; docs/tests for headers & proxy

[AliYmn]

Summary by CodeRabbit

• New Features
  • Added optional rate-limit response headers (X-RateLimit-*, Retry-After).
  • Support for custom keying to rate-limit by user, API key, or path.
  • Proxy-aware mode to respect X-Forwarded-For behind trusted proxies/CDNs.
• Documentation
  • Expanded README and docs with new configuration options, examples, notes, and updated guidance/roadmap.
• Tests
  • Added coverage for headers, Retry-After, proxy handling, and custom key functions.
• Chores
  • Bumped version to 0.1.8.
  • Updated development dependency: pytest-cov version change.

[coderabbitai]

Caution

Review failed

The pull request is closed.

Walkthrough

Extends RateLimiter to support custom keying, proxy-aware IP resolution, and optional rate-limit headers with Retry-After. Updates documentation and examples accordingly, adds tests for new behaviors, bumps package version to 0.1.8, and adjusts a dev dependency version.

Changes

Cohort / File(s)	Summary of Changes
Core Limiter Logic fastapi_throttle/limiter.py	Added key_func, trust_proxy, add_headers options; switched to monotonic timing; updated key resolution (X-Forwarded-For support); modified call to accept Response; emits X-RateLimit-* and Retry-After headers; refined in-memory storage and pruning.
Documentation README.md, index.rst	Documented new options and usage patterns (custom keying, proxy-aware mode, headers); updated notes, limitations, features, and roadmap; added advanced examples.
Tests tests/test_limiter.py	Added tests covering headers emission, Retry-After behavior, proxy trust flow, and custom key function per-user limits.
Packaging & Dependencies setup.py, requirements.txt	Version bump to 0.1.8; changed pytest-cov version from 6.2.1 to 5.0.0.

Sequence Diagram(s)

sequenceDiagram
  autonumber
  actor Client
  participant ASGI as FastAPI
  participant RL as RateLimiter
  participant Store as In-memory Store
  participant Resp as Response

  Client->>ASGI: HTTP request
  ASGI->>RL: __call__(Request, Response)
  RL->>RL: Resolve key<br/>(key_func | X-Forwarded-For | client.host)
  RL->>RL: Compute window (monotonic)
  RL->>Store: Load/prune timestamps for key
  alt Within limit
    RL->>Store: Append current timestamp
    RL-->>Resp: Optionally set X-RateLimit-* headers
    ASGI-->>Client: 2xx response
  else Exceeds limit
    RL->>RL: Compute Retry-After
    RL-->>Resp: Set Retry-After (and optional headers)
    ASGI-->>Client: 429 Too Many Requests
  end

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Estimated code review effort

🎯 4 (Complex) | ⏱️ ~60 minutes

Poem

I tap my paw—one, two—then wait,
Count grains of time at the garden gate. ⏳
New keys, trusted trails through proxy air,
Headers whisper, “how many left?”—fair and square.
When bursts abound, I pause—no fret—
Retry-After—then onward, yet! 🐇

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📥 Commits

Reviewing files that changed from the base of the PR and between 4d686a1 and 8db015b.

📒 Files selected for processing (6)

• README.md (6 hunks)
• fastapi_throttle/limiter.py (3 hunks)
• index.rst (3 hunks)
• requirements.txt (1 hunks)
• setup.py (1 hunks)
• tests/test_limiter.py (1 hunks)

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