feat(rate-limiter): implement leaky bucket rate limiting algorithm

[halvaradop]

Description

This pull request implements the Leaky Bucket rate-limiting algorithm.

The algorithm can be used through the centralized createRateLimiter API or directly via the dedicated createLeakyBucketAlgorithm function.

The Leaky Bucket algorithm enforces a constant outflow rate by allowing requests to accumulate in a bucket with a fixed capacity while continuously leaking requests at a configured rate. This approach helps smooth traffic bursts and provides predictable request processing over time.

Usage with createRateLimiter

import {
  createRateLimiter,
  createMemoryStorage,
} from "@aura-stack/rate-limiter"

const limiter = createRateLimiter({
  storage: createMemoryStorage(),
  rules: {
    signIn: {
      algorithm: "leaky-bucket",
      capacity: 10,
      leakRatePerMs: 0.001,
      keyGenerator: (req: Request) =>
        req.headers.get("x-forwarded-for") ?? "unknown",
    },
  },
})

await limiter.signIn.check(
  new Request("http://incoming.request")
)

Direct Usage

import {
  createLeakyBucketAlgorithm,
  createMemoryStorage,
} from "@aura-stack/rate-limiter"

const signInLimiter = createLeakyBucketAlgorithm({
  algorithm: "leaky-bucket",
  capacity: 10,
  leakRatePerMs: 0.001,
  storage: createMemoryStorage(),
  keyGenerator: (req: Request) =>
    req.headers.get("x-forwarded-for") ?? "unknown",
})

await signInLimiter.check(
  new Request("http://incoming.request")
)

Features

• Leaky Bucket rate-limiting algorithm
• Integration with createRateLimiter
• Direct usage through createLeakyBucketAlgorithm
• Configurable bucket capacity and leak rate
• Burst traffic smoothing
• Compatible with all supported storage adapters
• Custom request key generation

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1 Skipped Deployment

Project	Deployment	Actions	Updated (UTC)
auth	Skipped		Jun 10, 2026 8:30pm

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ℹ️ Review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: b5e6b7f7-5b9b-49a5-913a-726ffa84a932

📥 Commits

Reviewing files that changed from the base of the PR and between 5d429a1 and fcd906a.

📒 Files selected for processing (6)

• packages/rate-limiter/CHANGELOG.md
• packages/rate-limiter/src/algorithms/index.ts
• packages/rate-limiter/src/algorithms/leaky-bucket.ts
• packages/rate-limiter/src/rate-limiter.ts
• packages/rate-limiter/src/types.ts
• packages/rate-limiter/test/algorithms/leaky-bucket.test.ts

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch feat/add-leaky-bucket-alg

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