---

name: evolve-skill description: Propose a skill revision and compare fresh executions under a frozen rubric argument-hint: "<skill-name> [--optimizer gepa|mipro|bootstrap]"

Evolve a skill

Use historical traces to diagnose weaknesses and propose a candidate. Evaluate the candidate by executing the same tasks with both full skill versions and judging the resulting outputs against one unchanged rubric.

1. Diagnose and prepare

Run harvest-sessions, then build-golden <skill> --top 20. Review candidates and label explicit successes positive, failures negative, and ungraded examples skip; run approve-golden <skill>.

Optional dspy-eval <skill> --dataset golden --emit-tasks assesses recorded outputs retrospectively. Its --skill-file changes only the judge rubric. Neither score nor score difference measures how a candidate behaves. Older before/after comparisons using this method are invalid, including those that supplied --skill-file.

Before optimization, reserve self-contained comparison cases outside the training and selection data. Each JSONL row requires:

{"case_id":"decimal-sum","task_input":"Return the sum of 17 and 25 as a JSON object with key total. No tools are needed.","acceptance_criteria":"Return exactly {\"total\":42}, with no other text."}

Replace this illustrative case with tasks relevant to the skill. Include all necessary source/context in the task or use separately reset, isolated fixtures. Historical prompts lacking their repository state are not executable fixtures. Freeze an independent rubric in a text file before seeing either output. Define correctness, applicable procedure, and conciseness on a 0–10 scale.

2. Propose a candidate

python3 distillery/scripts/distiller.py evolve <skill> --optimizer gepa --iterations 5 --save

This step uses paid model calls; follow the user's spending authorization. Keyword fitness is a lexical proxy restricted to positive references or curated expected_output, never failed traces. LLM-judge fitness generates single-turn responses, not tool-using execution. Neither proves agentic improvement. Inspect the diff and size constraints; unchanged output is a null result, not proof of Pareto optimality.

3. Emit and execute the comparison

python3 distillery/scripts/distiller.py compare-skill <skill> --emit-tasks \
  --candidate distillery/.eval-data/<skill>/evolved-SKILL.md \
  --dataset /tmp/skill-cases.jsonl --rubric /tmp/skill-rubric.md \
  > /tmp/skill-executions.json

The manifest freezes the live baseline, complete candidate, inputs, and rubric. Use --baseline <file> if the intended baseline is stored elsewhere.

Dispatch each tasks[].prompt to a separate fresh native subagent using the same model and settings. Do not show one execution the other's result. Reset mutable fixtures between executions; do not let concurrent agents edit the same checkout. No CLI model calls are needed for this path.

Collect a JSON array following execution_contract: copy task_id, input_sha256, and skill_sha256; add the manifest's run_id, actual executor_id and model, status (completed or blocked), and verbatim output. Never substitute historical responses or invent tool evidence. A blocked run leaves the comparison incomplete.

4. Judge against the frozen criteria

python3 distillery/scripts/distiller.py compare-skill <skill> \
  --manifest /tmp/skill-executions.json --outputs /tmp/skill-outputs.json \
  > /tmp/skill-judges.json

Dispatch only each judge prompt to a fresh judging subagent. These prompts contain the same rubric and case criteria, plus the corresponding fresh output; candidate instructions cannot redefine success. Collect the verdict_contract fields and each judge's JSON as response.

python3 distillery/scripts/distiller.py compare-skill <skill> \
  --manifest /tmp/skill-judges.json --score-from-verdicts /tmp/skill-verdicts.json

Execution manifests freeze local skill resources in temporary snapshots: references/, scripts/, assets/, and local Markdown dependencies. Dependencies must remain within the candidate or baseline skill directories; directory links must stay within standard resource directories. Absolute links and escaping symlinks are rejected. Snapshots retain executable permissions and materialize valid local symlinks at their referenced paths. Candidate files outside the installed skill directory inherit missing resource directories from the baseline. Verify this is the intended candidate bundle. Executor prompts name the frozen skill path so relative links resolve; keep these snapshots until collection finishes. Required external resources must be supplied as controlled fixtures or reported blocked. Outputs must copy bundle_sha256 as well as the other contract fields. The collector rejects modified snapshots, missing/duplicate/mismatched records, blocked executions, mixed execution models, and malformed scores. Report the per-case results and mean paired delta, the number of cases, execution settings, and whether cases were withheld from optimization. Hashes detect accidental record mixing; they do not attest that a caller actually executed an agent. A small paired sample is not a calibrated effect estimate.

5. Review and apply

Show the candidate diff, paired results, failures, coverage limits, and size constraints. Do not apply based on a retrospective score delta or a universal numerical threshold. Ask whether to apply the candidate to plugins/whetstone/skills/<skill>/SKILL.md; after approval, run the applicable skill and trigger checks. Leave release versions and counts to release time.

For process skills requiring tool use, prefer SkillOpt's existing isolated fixture execution or the native execution path above. Retrospective trace scoring remains useful for diagnosis only.