Per Phase A finding A6 — the previous three-watcher Pinia-store design had
no validation. Landing on /events/{e}/timetable?day=DOES_NOT_EXIST quietly
set store.activeDayId to that bogus value and showed an empty page.
Cross-org sub-event IDs were silently accepted (backend OrganisationScope
returned an empty perf list, so the UI looked broken without telling the
user).
New design (Session 4 follow-up Step 5):
- src/composables/timetable/useActiveDay.ts (NEW)
- The URL `?day` is the source of truth; Pinia does NOT hold this value.
- `activeDayId` is a computed: queryDay if it appears in `validIds`,
else the first valid id, else null when the list is empty.
- One corrective watcher (immediate:true, flush:'post') quietly rewrites
the URL when `?day` is missing or invalid; runs after Vue settles and
after validIds has been recomputed from a fresh fetch.
- `setActiveDay(id)` is the user-driven entry point — calls replace().
- Cross-org IDs are blocked transparently: OrganisationScope keeps them
out of validIds, so they fail the .includes() check and fall back.
- src/stores/useTimetableStore.ts
- Removed `activeDayId` state and `setActiveDay()` action; the store
docstring now documents that day-state lives at the URL.
- src/pages/events/[id]/timetable/index.vue
- Replaced the three watchers + onMounted bootstrap with one
`useActiveDay({ queryDay, validIds, replace })` call. The day-change
side-effect watcher (clear drag, deselect performance) stays.
- VTabs binds dayIdRef + setActiveDay directly.
- tests/unit/pages/timetableDaySync.test.ts (NEW, 9 tests)
- Valid ?day=X → activeDayId=X, no URL rewrite.
- Missing / invalid / cross-org ?day → fallback + URL replaced once.
- Empty validIds → activeDayId=null, URL untouched.
- setActiveDay(id) → calls replace.
- setActiveDay(null) → no-op.
- External URL change (browser back) → activeDayId follows.
- validIds populated AFTER mount → fallback fires correctly.
- tests/unit/stores/useTimetableStore.test.ts: assert that activeDayId
and setActiveDay are GONE from the store surface.
Test count: 324 → 333.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
bert.hausmans
e99acbde95