What problem does it solve? Implementation plans often need revision after review, but ad-hoc edits risk inconsistency, stale file references, and unverified assumptions. This Skill provides a disciplined workflow for modifying existing plan files so every change is grounded in actual codebase reality. ## Core Features & Use Cases - Feedback-Driven Plan Updates: Reads the entire existing plan, parses requested changes, and applies surgical edits while preserving structure and file:line references. - Research-Backed Changes: Spawns parallel research agents (codebase locator, analyzer, pattern finder) when feedback requires new technical understanding before editing. - Confirmation Workflow: Presents understanding and planned modifications for user approval before touching the plan file. - Use Case: A reviewer asks to add a caching phase to a plan in _scratchpad/plans/. The Skill researches existing cache patterns in the codebase, confirms the approach, then inserts a new phase following the plan's existing format with updated success criteria. ## Quick Start Update the plan in _scratchpad/plans/ based on my feedback about adding error handling to the authentication phase.