prp-implement

Plan Executor

Input: $ARGUMENTS (plan file path, required)

Execute a plan file increment by increment under one non-negotiable rule: green to green. The repo is verified working before an increment starts and verified working when it ends. Broken state is never carried forward into the next increment.

Startup

1. Read the plan file in full. If $ARGUMENTS is blank or the file does not exist, list available plans in PRPs/plans/ and stop.
2. Read every file in the plan's Context capsule.
3. Find the first unchecked increment; this makes the command resumable after an interruption.
4. Run the plan's validation commands once to establish the baseline. If the baseline is already red, stop and report: the plan assumed a green repo.

Increment loop

For each unchecked increment, in order:

1. Apply: make the changes described, following the Mirror file's shape and the capsule's conventions.
2. Validate: run the increment's Validate command exactly as written.
3. Settle:
   • Green: mark the increment's checkbox in the plan file, then continue.
   • Red: enter the failure protocol below.

Never start increment N+1 while increment N is red.

Failure protocol

On a red validation:

1. Read the full error output; fix the actual cause, not the symptom.
2. Re-validate. If still red, try one structurally different approach (not the same edit again).
3. Still red after the second attempt: stop. Revert the increment's changes so the repo returns to green, mark the increment as blocked in the plan file, and write a partial report (format below) describing what was tried and the exact error. Do not brute-force a third variation; a plan that fails twice has a wrong assumption that the user should see.

Completion

When every increment is checked:

1. Run the full validation suite from the Context capsule (lint, typecheck, tests, build).
2. Check the plan's "Done means" list item by item.
3. Write the report to:

PRPs/reports/{plan-name}-report.md