Split the app into the three pages the navbar promises, each with one job:
- / (home) -> read-only roster, no mutation controls
- /add -> create only, redirects to / on success
- /edit -> update + delete only (picker, plus /edit?id=<uuid> deep links)
Data layer (src/lib/students.ts) is the single source of truth:
- zod studentDraftSchema validates form input (trims name, lowercases email,
coerces yearLevel to an int 1-5, restricts course to a known list)
- studentSchema = draft + id + createdAt, so types come from z.infer
- versioned key it3206.students.v1, validated on read *and* write; corrupt or
missing data degrades to an empty list instead of throwing
- typed CRUD helpers; useSyncExternalStore hook with a stable snapshot cache,
a window event and the storage event so every island and other tabs re-render
Footer "clear local storage" is now wired to clearStudents() (confirm dialog,
label feedback) instead of being inert, and the layout switched to min-h-svh +
an in-flow footer so it no longer overlaps long lists. Footer padding clears the
Astro dev toolbar, which was covering the link in dev.
Also adds zod, plus @astrojs/check + typescript@^6 as dev deps so astro check
runs (TS 7 does not expose the API astro check needs yet).
