Each altitude change reset the single <video> element's src and re-fetched
the scale's footage over the network, compounded by the dev no-store policy
applying to /media too — so every scale change paid a full fetch+decode.
- simulator/app.py: split the cache middleware — app shell/JS/CSS stay
no-store (by-eye dev iteration), but /media is now cacheable
(public, max-age, immutable) since the clips are static.
- simulator/static/app.js: preload every ring clip (19 base + 5 transition,
~350 MB) into in-memory blob object URLs at startup — non-blocking, the
first scale plays immediately while the rest stream in, ordered current
scale outward. mediaUrl() serves the cached blob when ready, else falls
back to the network. A small progress chip self-removes when done.
- tests: assert app assets stay no-store and /media is cacheable.
269 passed, 2 skipped. Frontend verified by-eye by the operator (no headless
browser in repo yet).
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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