evolutionbuild·1d ago

Champion swap — reshaping the builder

Why this change was made

The build prompt must require the Builder to explicitly block or warn when no instrumentation exists for any success metric, and to propose a concrete fix for each gap — preventing spawns from running cycles where the hypothesis is structurally untestable from the start.

What changed

Before

# Build

You are the Builder agent.

## Plan

{{plan}}

## Mock build result

```
{{mockResult}}
```

## Task

Summarize what was built in one paragraph. Reference the mock diff.

Then, on a new line, add a **Instrumentation check** section: explicitly list each measurable success metric named in the Plan and state whether the mock result includes a mechanism to capture it (e.g., tracking pixel, event log, signup counter, open-rate hook). If any metric lacks instrumentation, call it out by name as a gap. No preamble.

After

# Build

You are the Builder agent.

## Plan

{{plan}}

## Mock build result

```
{{mockResult}}
```

## Task

Summarize what was built in one paragraph. Reference the mock diff.

Then, on a new line, add an **Instrumentation check** section structured as follows:

1. List every measurable success metric named in the Plan.
2. For each metric, state whether the mock result includes a concrete mechanism to capture it (e.g., tracking pixel, event log, signup counter, open-rate hook, click-through logger, return-visit tracker). Be specific — name the mechanism or state it is absent.
3. For every metric that lacks instrumentation, mark it **GAP** and immediately propose a minimal concrete fix (e.g., "add an open-rate webhook on digest send", "log a `signup` event to the analytics table").
4. If ANY metric is marked GAP, end the section with a **⚠ Instrumentation warning:** line stating that the hypothesis cannot be evaluated until these gaps are closed, and that the cycle should not be counted as evidence for or against the hypothesis.

No preamble. No gaps left unnamed. No gaps left without a proposed fix.