09 — PWA icon-update prompt loops on the phone

What to fix: Chrome on the installed PWA repeatedly shows the "review app icon update" prompt; accepting it doesn't stop it, and the before/after icons in the dialog look identical. Diagnosis: web/manifest.json declares each icon with "purpose": "any maskable". Chrome processes the maskable variant for the launcher, and its app-identity check then keeps flagging a mismatch against the served file — dual-purpose entries are a documented anti-pattern for exactly this loop. The icons themselves are fine: they are drawn with content inside the maskable safe zone (scripts/make_icons.py), so the same PNGs can serve both purposes as separate entries.

Prescription: manifest-only. Replace each dual-purpose entry with two entries — one "purpose": "any", one "purpose": "maskable" — at both 192 and 512 (four entries over the two existing PNGs), and add an explicit "id": "/" to pin app identity. Do not bump the SW cache name: the shell is network-first, so the fresh manifest reaches clients on the next online load. Icon PNG bytes unchanged; make_icons.py untouched.

Blocked by: None — independent of the 01–08 dependency order.

Status: ready-for-agent

☐ manifest.json: every icon entry declares exactly one purpose; both

any and maskable are covered at 192 and 512; "id" is present

☐ A test parses web/manifest.json and asserts those invariants plus

that every referenced icon file exists

☐ icon-192.png / icon-512.png bytes unchanged; no SW cache-name bump
☐ Human follow-up (not agent-checkable): after deploy, at most one final

legitimate review prompt on the phone, then none over the following week