gsd--execute-phaselisted

# GSD — Execute Phase ## Hard Prerequisites PLAN.md must exist. If it doesn't, say: "No PLAN.md found. Run 'plan phase <N>' first." Do not proceed without it. ## Steps ### Step 1: Read PLAN.md Read the full plan. Note the task order and dependencies. ### Step 2: TDD Setup For any task that creates new functions or modules: write the failing test FIRST. Commit the failing test stub before writing implementation. See the `tdd` skill. ### Step 3: Execute Tasks in Order For each task in PLAN.md: 1. Implement the task 2. Run its verification step 3. If it passes: commit with `feat(<phase>): <task description>` + DCO sign-off 4. If it fails: fix it before moving to the next task 5. Mark ✅ in session log ### Step 4: Deviation Handling If execution deviates from PLAN.md: document the deviation, explain why, and confirm before proceeding with the alternative approach. Never silently ignore plan deviations. ## Exit Condition All tasks in PLAN.md marked ✅, all local tests pass, all commits have DCO sign-off.