Lab 13 — Capstone: planner → generator → evaluator

Start from: app/ at tag lab12-done, with the Lab 0 setup loaded (see Working in app/).

Goal: combine everything: separate roles with separate tool envelopes, a human approval gate, a machine-checked verdict and a bounded revision loop. Read pge.ps1 (or pge.sh):

flowchart LR
  P["planner<br/>read-only"] --> Hhuman approves<br/>PLAN.md
  H --> G["generator<br/>Edit/Write + pytest"]
  G --> E["evaluator<br/>fresh session, read + pytest + git diff<br/>JSON verdict"]
  E -->|FAIL, ≤ 2 revisions| G
  E -->|PASS| D[human reviews diff and commits]

The evaluator is a fresh session. It doesn’t see the generator’s reasoning, only the plan, the code and the test results. That independence is the point.

1. Run it on a feature branch

git switch -c feature/receipt
..\lab13-capstone\pge.ps1 -Feature "Add a 'receipt' CLI command: python cli.py receipt P1:2 P3:1 --code SAVE10 prints an itemized receipt with line totals, discount, tax and grand total, all from integer cents. Include tests."

git switch -c feature/receipt
bash ../lab13-capstone/pge.sh "Add a 'receipt' CLI command: python cli.py receipt P1:2 P3:1 --code SAVE10 prints an itemized receipt with line totals, discount, tax and grand total, all from integer cents. Include tests."

(Adjust the flags if your Lab 4 discount design differs.) When the script pauses, read PLAN.md. Edit it if you disagree; the generator follows the file. Then press Enter.

2. Observe the roles

• Planner: which files did it read? Did it touch anything? (It can’t.)
• Generator: turns, files changed, hook events.
• Evaluator: its JSON verdict and reasons. If it said FAIL, did the revision fix exactly what it flagged?
• Every node’s events are in .runs/pge-*.jsonl.

3. Review and finish as the human

git diff --stat main
python -m pytest -q

Nothing is committed automatically. If you agree with the verdict, commit (Conventional Commit message), merge into main, and maybe run /release-notes from Lab 8.

Record

| Node | Turns | Cost | Tools used | Output | |—|—|—|—|—|

Plus: did the evaluator catch anything you would have missed? Did it pass something you’d reject?

Checkpoint

git switch main ; git merge --no-ff feature/receipt
git tag lab13-done