demo · v143
Icon immutability
The half of the spec that's about saving bytes: PWA icon URLs now count as Cache-Control: immutable. If the URL didn't change, the browser doesn't re-fetch even when the manifest changed. Live: type icon URLs and headers, see whether v143 would re-fetch.
old manifest
new manifest
before v143
v143 behaviour
Set URLs and headers, click Apply v143 rule.
the rule
// v143: a PWA icon URL is treated as effectively immutable.
// If old.icon.src === new.icon.src AND the URL hasn't changed,
// the browser skips re-fetching even when the manifest updates.
// To force a new icon, rev the URL:
// /icon-192.png → /icon-192-v2.png (cache-busted)
// /icon-192.png?v=1 → /icon-192.png?v=2
why this angle
The other concept covers the broader update_eligibility schema. This one isolates the Cache-Control: immutable change, which is the single biggest network optimisation for PWAs that change their manifest often but keep the same icons. Shows what counts as "the same icon".