# Forever Fibers — Durable Execution Demo > **WARNING: EXPERIMENTAL.** This example uses APIs from `agents/experimental/forever` that are under active development and **will break** between releases. Do not use in production. Pin your package versions and expect to rewrite your code when upgrading. Demonstrates durable long-running execution with fibers — fire-and-forget work that survives Durable Object eviction via SQLite checkpointing and alarm-based recovery. See [forever.md](../forever.md) for the full design doc. ## What it shows - `withFibers` mixin from `agents/experimental/forever` - `spawnFiber()` — start a multi-step research task that runs in the background - `stashFiber()` — checkpoint progress after each step (persisted in SQLite) - `onFiberRecovered()` — automatically resume from the last checkpoint after eviction - `cancelFiber()` — stop a running fiber - Simulated eviction — demonstrates the recovery flow ## Run it ```bash npm install cd experimental/forever-fibers npm start ``` No API keys needed — research steps are simulated with delays.