chore: ignore and remove throwaway scratch files

.gitignore

@@ -25,3 +25,15 @@ docs/superpowers/
 reports/
 .superpowers/
 /plan/
+
+# Agent scratch / throwaway files - do not commit
+.tmp/
+HANDOVER*.md
+HANDOFF*.md
+handoff.md
+handover.md
+*-designs.html
+*-design.html
+*-mockup.html
+*-demo.html
+*-demos.html

AGENTS.md

@@ -77,3 +77,7 @@ This is a TypeScript monorepo built for agent-assisted development. Keep the roo
 - After finishing a task and before submitting a PR, you must run the `gen-changesets` skill (see `.agents/skills/gen-changesets/SKILL.md`) and generate a changeset under `.changeset/` according to its rules.
 - When generating a changeset, **never** decide on a `major` bump on your own. When you judge a change to meet the major criteria (breaking changes, incompatible user configuration, renamed or removed commands/arguments, changed behavior semantics, etc.), you must stop and explain it to the user and ask for confirmation. **Only write `major` after the user has explicitly agreed.** Otherwise default to `minor` (and fall back to `patch` if `minor` is unclear). See the "Hard rule: confirm with the user before writing `major`" section in `.agents/skills/gen-changesets/SKILL.md` for details.
 - Prefer importing via `import ... from '#/...'`, which serves the same purpose as `import ... from '@/...'`.
+- Do not commit throwaway scratch or exploratory files. Never stage:
+  - Agent working notes or handoff/summary documents (e.g. `HANDOVER-*.md`, `HANDOFF-*.md`, `handoff.md`).
+  - Throwaway UI/UX prototypes or design mockups (e.g. `*-designs.html`, `*-mockup.html`, `*-demo(s).html`) at the repo root or under a `design/` folder. The only tracked `.html` files should be Vite `index.html` entrypoints.
+  Before committing or opening a PR, run `git status` and `git diff --staged --stat` and remove anything matching these patterns. Put scratch work under `.tmp/` (gitignored) instead of the repo root or the source tree.