Use when the Kickbacks/vibe-ads ad extension owns the Claude Code statusline and the user wants the Yuumi Tokyo Night statusline back WITHOUT removing the ad — installs a combined HUD+ad statusline and locks it against the extension's rewrites (Claude Code only; macOS/Linux)
Agree on domain, package location, responsibility, and function signatures before implementing — sketch the skeleton, record a design note, hand off code to yuumi:implement. Invoke by hand.
Use when a document carries inline {curly-brace} edit notes to apply in place, or when scattered edits across long drafts or multiple files must stay consistent — no copy-paste round-trips
Use when a file, endpoint, module, system, concept, or change (a PR, branch, or diff) needs to be genuinely understood, not skimmed — renders a single-file Anthropic-style HTML explainer that installs a mental model in one read; add a comprehension quiz when the user wants their understanding verified ("a quiz I must pass")
Use when implementing a spec whose reviewer will need the decision trail — resolved ambiguities, deviations, tradeoffs, open questions — not just the diff; keeps a running single-file HTML decision log alongside the code
Use when a plan or spec needs pressure-testing before you build it — finds the holes through an in-depth interview rather than a passive review
Use when a deliverable should be a polished single-file HTML page — a report, explainer, design note, comparison, or anything too long or too visual for chat — rendered in the warm editorial Yuumi visual system
Actively understand a change someone else made — a PR, branch, or diff you did not write — through a dialogue walkthrough (prediction, tracing, rough sketches) before you judge it. Use when starting a PR review or making sense of an unfamiliar diff.