What problem does it solve? Rebuilding a chapter's teaching notebook after physics fixes, new explainers, or teaching feedback requires re-briefing the builder agent, re-executing the notebook, and re-validating embeds by hand, which is repetitive and error-prone. ## Core Features & Use Cases - Change Request Handling: Appends the user's requested change to the chapter's design document under a dated Revisions section before rebuilding. - Agent-Orchestrated Rebuild: Briefs the notebook-builder agent using the phase 8 brief format from the /do-chapter workflow. - Execution Gates: Runs tools/run_notebook.py and tools/embed_check.py headlessly and requires OK output before committing. - Use Case: After fixing a derivation in Chapter 7, run the skill with a change note, and it rebuilds, executes, validates, commits, and republishes the chapter notebook and its Colab twin. ## Quick Start Rebuild chapter 7's teaching notebook and add a tiny worked example for group velocity before executing and validating it.