implement-planlisted

# Implement Plan Build-phase entry skill. Execute the approved plan with discipline: TDD where it matters, surgical edits, fresh-context reviewer pattern for delegated work, worktrees only when parallel filesystem isolation is real. ## Iron Rule <EXTREMELY-IMPORTANT> 1. NEVER edit code without reading the plan and the touched files first. 2. NEVER expand scope mid-implementation. New idea → write it down and finish the planned task first. 3. ALWAYS write the failing test first for bug fixes and high-risk-surface work. 4. NEVER delegate to a subagent without a written task scope and a clear done criterion. 5. CONTINUOUS execution between tasks AND between plan phases — no "should I continue?" check-ins, no progress summaries, and never end the turn mid-plan: an ended turn is a stop no matter how it is worded. Stop only on BLOCKED that the Lead cannot resolve, a spec/plan gap, or scope ambiguity. </EXTREMELY-IMPORTANT> ## When to use - A plan (formal or informal) exists and the next step is editing - A small one-file edit is clear from the conversation - Bounded delegation to a specialist is needed - Two engineers (or sessions) need filesystem isolation Skip when: - The task is a question only - The plan is still vague — go back to `write-plan` first ## Boundary Owns: - Executing the approved plan. - Reading touched files, making surgical edits, writing/running task-level tests, bounded delegation. Does not own: - Changing product scope. - Redesigning the plan silently