PWA never calls registration.update() — long-lived sessions run a stale shell #274

Deployment-readiness gap (#244), RECOMMENDED — frontend.

Problem

A long-lived PWA session never re-checks for a new deploy, so barn phones keep running the old app shell against a freshly deployed API. The service-worker config is deliberately correct for avoiding mid-form swaps — registerType: "prompt", injectRegister: null, no skipWaiting (web/vite.config.ts) — and the manual registration handles waiting/installing/updatefound well (registerServiceWorker.ts). But there is no registration.update() call anywhere (no interval, no visibilitychange handler). A display: standalone PWA left open all day generates no navigation, so the browser never re-fetches sw.js, updatefound never fires, and the UpdatePrompt never appears — the client keeps serving the old precached index.html/shell against the new /api/v1. Stable URL versioning limits the blast radius, but a breaking deploy strands long-lived sessions until manual relaunch.

Fix

Add a periodic registration.update() (and one on visibilitychange → visible) so the update prompt can surface without a full reload. Keep the prompt-not-auto-update behavior. Ships with Vitest coverage (standing rule for web/ changes).

Verify

With a session open, deploy a new build; confirm the UpdatePrompt appears within the poll interval without a manual reload.

Part of the #244 deployment-readiness audit; tracked in epic #15.