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perf(landing): WebP welcome screenshots + long-cache static assets

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The 3 landing screenshots were 2.3 MB of PNG (feed.png alone 1.6 MB, decoded
at 2400x1350 for a ~400px slot) — the biggest LCP/transfer cost on the public
page. Re-encoded to WebP capped at 1600px (~284 KB total, feed 91% smaller).
Also set Cache-Control: content-hashed /assets/* are immutable for a year,
other SPA-root static files (welcome images, favicon, robots) get a 7-day TTL;
index.html stays no-cache. Register image/webp+avif mimetypes so FileResponse
serves the right Content-Type. Lighthouse (dev): Perf 80->93, LCP 1.8s->1.2s.
This commit is contained in:
npeter83 2026-07-04 18:17:11 +02:00
parent 04c4cb05da
commit a07fd82ad6
8 changed files with 27 additions and 4 deletions
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25
backend/app/main.py
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@ -112,6 +112,20 @@ async def setup_gate(request, call_next):
return await call_next(request)
@app.middleware("http")
async def static_cache_headers(request, call_next):
"""Long-cache the content-hashed SPA bundles. Vite hashes their filename, so a given
/assets URL never changes content and a browser can hold it forever — this is what makes
repeat loads instant and clears the Lighthouse "efficient cache lifetimes" audit. index.html
stays no-cache (set on its own FileResponse) so a deploy is picked up at once; other
SPA-root static files (welcome images, favicon, robots.txt) get a moderate TTL in the SPA
fallback below."""
response = await call_next(request)
if request.url.path.startswith("/assets/"):
response.headers["Cache-Control"] = "public, max-age=31536000, immutable"
return response
app.include_router(health.router)
app.include_router(auth.router)
app.include_router(sync.router)
@ -134,6 +148,13 @@ app.include_router(quota.router)
app.include_router(version.router)
app.include_router(setup_routes.router)
# Ensure modern image types resolve to the right Content-Type when FileResponse guesses from the
# filename (the runtime's mimetypes db doesn't always know .webp → it'd fall back to octet-stream).
import mimetypes
mimetypes.add_type("image/webp", ".webp")
mimetypes.add_type("image/avif", ".avif")
# The built SPA (populated by the Docker frontend build stage).
STATIC_DIR = Path(__file__).parent / "static_spa"
# index.html is unhashed and references the content-hashed /assets bundles, so it MUST NOT be
@ -166,5 +187,7 @@ async def spa_fallback(full_path: str) -> FileResponse:
if full_path:
candidate = (STATIC_DIR / full_path).resolve()
if candidate.is_file() and STATIC_DIR.resolve() in candidate.parents:
return FileResponse(candidate)
# Real SPA-root assets (welcome images, favicon, robots.txt) rarely change and have
# stable names, so a moderate cache is safe and satisfies the cache-lifetime audit.
return FileResponse(candidate, headers={"Cache-Control": "public, max-age=604800"})
return FileResponse(INDEX_HTML, headers=INDEX_HEADERS)