Add homepage tag discovery matrix

README.md

@@ -112,6 +112,40 @@ prefers reduced motion. When hero styles or behavior change, increment the
 corresponding `style.css` or `section-heroes.js` cache-busting version in
 `templates/base.html`.
 
+## Homepage tag discovery
+
+The homepage ends with an **Explore the Signal** topic matrix immediately after
+Recent Activity and Featured Projects and before the site footer. It is a
+server-rendered discovery route over the canonical child records under
+`content/tags/`; it does not maintain a separate topic list. Each topic is a
+normal link to its dedicated `/tags/<slug>/` page and includes its current
+published usage count.
+
+Counts use the same discovery scope as the tag directory and dedicated tag
+pages: projects, project devlog entries, blog entries, and articles. The matrix
+uses four restrained visual levels for counts of 0–1, 2–3, 4–7, and 8 or more.
+The displayed count remains exact while the highest visual level is capped, so
+a frequently used tag cannot dominate the layout. Tag records and content
+changes update the matrix automatically on the next normal project-aware build.
+
+`assets/static/tags.js` progressively updates the Tag Summary readout when a
+visitor hovers or focuses a topic. The summary is optional enhancement only:
+every link remains visible, keyboard accessible, touch friendly, and usable
+with JavaScript disabled. Styling lives in `assets/static/style.css`, uses the
+existing Labyricorn gold treatment, wraps without horizontal scrolling, and
+removes the small focus/hover lift for reduced-motion users. When these assets
+change, increment their cache-busting versions in `templates/base.html`.
+
+After changing the homepage matrix:
+
+1. Run `python scripts/build_with_projects.py --output-path build` with the
+   Lektor runtime documented below.
+2. Confirm the generated homepage topic count matches the tracked registry and
+   every topic links to its existing tag page with the expected usage count.
+3. Check desktop and narrow layouts, keyboard focus, the summary enhancement,
+   normal link navigation, and the transition into the footer.
+4. Run `python -m unittest discover -s tests -v` and `git diff --check`.
+
 ## Routine content workflow
 
 Edit in a normal Git checkout, review the changes, and push them to `main`.