Shows: evolve (2.2) on a small JavaScript function. Only the code between the EVOLVE-BLOCK-START / EVOLVE-BLOCK-END markers may change; the model answers with a SEARCH/REPLACE diff that multiplies the number of Leibniz terms by ten, and a two-stage cascade scores each candidate: a cheap shape check with a threshold, then digits, the correct digits of π the function returns. Candidates go to createSqlitePopulationStore. The first run is killed before generation 2 commits (its commitGeneration never returns), and resumeEvolve from a new store connection replays the two stored generation-2 slots with modelCalls: 0.
Run: from the repo root, npm install && npm run build, then npm run dev -w @deuz-examples/10-evolve. No API key needed. It needs node:sqlite, which ships unflagged from Node 22.13 and 23.4. The SQLite file lives in a temporary directory that the example removes at the end.
Real provider: the model is createMockModel from @deuz-sdk/core/testing, which always proposes the same diff. Put a real model in models instead, such as { model: createAnthropic({ apiKey: process.env.ANTHROPIC_API_KEY })('claude-opus-4-8') } from @deuz-sdk/core/anthropic (see the REAL PROVIDER comment in index.ts); with several entries a UCB1 bandit picks one per slot. Drop patch: { diff: 1 } to let full rewrites and crossovers mix in.
Look at: the deterministic candidate IDs (g{generation}-i{island}-s{slot}): a resumed run finds every slot it already paid for. budget is mandatory. The evaluator runs the candidate with node:vm and a timeout, which bounds its run time but is not a security boundary: run model-written code in a worker, a container or a remote sandbox.