---
name: experiment-finalize
context: fork
description: Finalize an experiment session into clean, reviewable branches. Use when asked to "finalize experiment", "clean up experiments", or "prepare experiment for review".
---

# Finalize Experiment

Turn a noisy experiment branch into clean, independent branches — one per logical change, each starting from the merge-base.

## Step 1 — Analyze and Propose Groups

1. Read `experiment.jsonl`. Filter to **kept** experiments only.
2. Read `experiment.md` for context.
3. Expand all short commit hashes to full hashes: `git rev-parse <short_hash>`
4. Get the merge-base: `git merge-base HEAD main`
5. For each kept commit, get the diff stat (use `$BASE..<commit>` for the first, `<prev_kept>..<commit>` for subsequent).
6. Group kept commits into logical changesets:
   - **Preserve application order.** Group N comes before Group N+1.
   - **No two groups may touch the same file.** Each branch is applied to merge-base independently — overlapping files would conflict. If two groups touch the same file, merge them into one group.
   - **Watch for cross-file dependencies.** Each branch is independent, so if group 1 adds an API in `api.js` and group 2 calls it in `parser.js`, group 2's branch won't work in isolation. When proposing groups, flag dependencies: "group 2 depends on group 1 — review together." If the dependency is tight, merge the groups.
   - **Keep each group small and focused.** One idea, one theme per group.
   - **Don't hardcode a count.** Could be 2, could be 15.

Present the proposed grouping to the user:

```
Proposed branches (each from merge-base, independent):

1. **Switch test runner to forks pool** (commits abc1234, def5678)
   Files: vitest.config.ts, package.json
   Metric: 42.3s → 38.1s (-9.9%)

2. **Tune worker count and timeouts** (commits ghi9012, jkl3456)
   Files: test/setup.ts
   Metric: 38.1s → 31.7s (-16.8%)
```

**Wait for approval before proceeding.**

## Step 2 — Write groups.json and Run

Write `groups.json`:

```json
{
  "base": "<full merge-base hash>",
  "trunk": "main",
  "final_tree": "<full hash of current HEAD>",
  "goal": "short-slug",
  "groups": [
    {
      "title": "Switch to forks pool",
      "body": "Why + what changed.\n\nExperiments: #3, #5\nMetric: total_time 42.3s → 38.1s (-9.9%)",
      "last_commit": "<full hash of last kept commit in this group>",
      "slug": "forks-pool"
    }
  ]
}
```

Key rules:
- **`last_commit` must be a full hash.** Expand from jsonl short hashes with `git rev-parse`.
- **No two groups may share a file.** The script validates this and fails if violated.

Then run:

```bash
bash <SKILL_DIR>/finalize.sh /tmp/groups.json
```

The script creates one branch per group from the merge-base, verifies the union matches the original branch, and prints a summary with all branches, cleanup commands, and any ideas from `experiment.ideas.md`.

On creation failure: rolls back (deletes branches, restores original branch, pops stash).
On verification failure: exits non-zero but leaves branches intact for inspection.

## Step 3 — Report

After the script finishes, report to the user:
- Branches created and what each contains
- Overall metric improvement (baseline → best)
- Show the cleanup commands from the script's summary output

## Edge Cases

- **Only 1 kept experiment**: One branch is fine — don't force splits.
- **Overlapping files between groups**: The script fails with an error naming the file. Merge the overlapping groups and retry.
- **Non-experiment commits** on the branch: Skip them — only process kept experiments from the jsonl.