The drag handle + dndzone + reorderItems batch UPDATE were already wired
on the list detail view (Fase 5.10). One observable contract was missing:
when another client reorders an item, the local realtime UPDATE feed
shallow-merges the new payload onto the existing row but does NOT
re-position the row in the array — so the new order is invisible until
a reload. Fix: sort the `items` array by sort_order after every realtime
UPDATE / INSERT merge. Cheap (n is small per list) and matches the cold-
load order.
E2E (reorder-items.test.ts):
* RO-01: create 3 items, write a new sort_order via the same PATCH the
in-page reorderItems() helper does, reload, assert the reorder
persisted.
* RO-02: dual-context, Ana reorders, Borja sees the new order via
realtime within the suite's 10s window — without this commit's
sort fix the test failed because Borja's DOM order stayed at the
old order.
Drag emulation in headless Chromium is unreliable for svelte-dnd-action
(native HTML5 DnD). Both tests drive the same write path the page uses
(reorderItems = batch PATCH on sort_order) via fetch from inside the
browser context, using the session token the SDK has already stored.
The realtime + reload paths are unchanged.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
