[effect] Effect `AsyncLocalStorage` context lost/contaminated inside Effect fibers under concurrent load with RPC

**[effect] Effect `AsyncLocalStorage` context lost/contaminated inside Effect fibers under concurrent load with RPC**

Versions effect: 3.19.15 @effect/rpc: 0.72.1 @effect/platform: 0.94.2 Node.js: v22.20.0 Vercel runtime with Fluid compute Next.js: 16 (App Router) @clerk/nextjs: 6.x Root cause Effect's MixedScheduler batches fiber continuations and drains them inside a single microtask or timer callback. The AsyncLocalStorage context active during that callback belongs to whichever request first triggered the scheduler's drain cycle — not the request that owns the fiber being resumed. Scheduler batching (effect/src/Scheduler.ts, MixedScheduler) // MixedScheduler.starve() — called once when first task is scheduled private starve(depth = 0) { if (depth >= this.maxNextTickBeforeTimer) { setTimeout(() => this.starveInternal(0), 0) // timer queue } else { Promise.resolve(void 0).then(() => this.starveInternal(depth + 1)) // microtask queue } } // MixedScheduler.starveInternal() — drains ALL accumulated tasks in one call private starveInternal(depth: number) { const tasks = this.tasks.buckets this.tasks.buckets = [] for (const [_, toRun] of tasks) { for (let i = 0; i < toRun.length; i++) { toRun[i]() // ← Every fiber continuation runs in the SAME ALS context } } // ... } scheduleTask only calls starve() when running is false. Subsequent tasks accumulate in this.tasks until starveInternal drains them all...

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**[devsupporter 해설]**

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