---
id: improve.work-evolve
title: Work and Evolve
summary: Choose bounded implementation work or multi-branch evolutionary search with explicit epoch and provider authorization.
kind: task
product_area: improve
status: stable
updated: 2026-09-07
canonical: /docs/improve/work-and-evolve
---

# Work and Evolve

## Prerequisites

- A confirmed Goal Contract with exact starting evidence.
- A saved target Harness Version and canonical measurement bindings.
- Authorization for the selected worker source, epochs, and provider use.

Within the Coevolve experience, choose **Work** for one bounded implementation or investigation and **Evolve** when the confirmed Goal supports systematic exploration across several candidate branches and epochs. External Agents and External fine-tuning use different execution boundaries and should be selected only when their return or provider contracts are clear.

## Work

Work can run through Teammately or an offered external execution source such as Codex, Claude, or another worker. The source receives the confirmed Goal and scoped evidence. It must return an observable immutable Harness Version or evaluation request; a handoff package alone is not proof that private work occurred.

Use Work when the likely intervention is known, the change is narrow, or operator review should follow one candidate at a time. Review returned source, candidate identity, evaluation receipt, constraint result, and chronology before treating the work as complete.

## Evolve

Evolve uses Teammately and explores three Patch-to-Eval branches per epoch against the full pinned cohort. Choose **user-gated** to approve each epoch or **autonomous** to authorize a bounded number of epochs from 1 through 100. Set the target Case pass percentage and review provider usage by model.

An epoch does not merely generate text. Each viable branch must materialize an exact saved Harness Version and obtain canonical evaluation evidence before retention. Failed, incomparable, or constraint-violating branches remain visible rather than being presented as improvement.

## Select the mode

Use Work when evidence points to a specific retrieval filter, prompt rule, tool call, or output mapping change. Use Evolve when multiple independent interventions could satisfy the Goal and the benchmark can distinguish them. Do not use autonomous epochs when the Goal has unresolved authority, the evaluation boundary is unstable, or provider usage is not authorized.

> Epoch authorization
>
> User-gated and autonomous execution change how future epochs are scheduled, not the acceptance criteria. Every retained candidate still needs exact identity, canonical evaluation, and Goal-constraint compliance.

## Object and state changes

Starting Work or Evolve advances the Session and can create handoff packages, epoch branches, saved Harness Versions, evaluations, receipts, usage, and frontier decisions. Pause and cancellation preserve recorded evidence.

## Success criteria

- Mode and execution source match the problem.
- Every retained branch has exact candidate identity and canonical evidence.
- Epoch limits, pass target, and provider usage remain within authorization.

## Common failure modes

- Using Evolve before the benchmark can distinguish hypotheses.
- Treating a handoff package as returned implementation.
- Retaining a focused-only or constraint-violating candidate.

## Related reference pages

{% related-card-grid title="Related reference pages" %}
- [Goal Contracts](/docs/improve/goal-contracts)
- [Candidates and the Current Frontier](/docs/improve/candidates-and-frontier)
- [Chronology, Trajectories, and Receipts](/docs/improve/chronology-and-trajectories)
{% /related-card-grid %}

## Related troubleshooting pages

{% related-card-grid title="Related troubleshooting pages" %}
- [Benchmark runs](/docs/troubleshooting/benchmark-runs)
- [Benchmark results changed unexpectedly](/docs/troubleshooting/benchmark-results-changed-unexpectedly)
{% /related-card-grid %}

## Source confidence

Code-backed: the active Improve setup, session contract, and work-review model define sources, Work and Evolve modes, authorization styles, epoch bounds, three branches, pinned cohort, pass target, and provider usage.