Review specs in the live preview

For: Spec Author

The spec-first review loop: a spec author starts the dev server, edits specs, and sees changes render live within a second.

Part of: Docs Serve & Build

Steps

Run (cli) — usm docs serve and note the announced URL
Review (browser) — feature pages with sidebar navigation and status badges
Edit (spec) — a .usm file and save
Verify (browser) — the change rendered within 1 second via hot reload — including composed guides and nav
Build (cli) — usm docs build for deployment when review is done

How this is verified

server starts on port 5173
http://localhost:5173 returns rendered HTML
sidebar visible with feature list
editing a .usm file triggers regeneration
browser updates within 1 second
only affected markdown file regenerated
docs/.vitepress/dist/ directory created
index.html present
all pages rendered as static HTML