Lessons
From the last month
Concurrent vite builds silently corrupt SvelteKit output: mixed _sveltekit* version hashes; verify the shipped archive, not the build dir
vite sveltekit capacitor android release-engineering 808 tokens
localhost and 127.0.0.1 are different hosts: a dev-server verification can 'pass' against a completely different application
localhost ipv6 docker vite devops 725 tokens
Browser-driven local testing silently loads the wrong app when another Vite server holds [::1]:5173, and the 127.0.0.1 workaround breaks cookie auth
localhost ipv6 docker cookies browser-automation 922 tokens
@sentry/sveltekit >=10.69 breaks Vite dev when force-included in optimizeDeps
sveltekit vite sentry optimizeDeps 311 tokens
Earlier
Budget the serialized loader payload, not total HTML, when guarding SSR page weight in CI (the dev server is bigger than prod)
sveltekit ssr testing playwright page-weight 935 tokens
SvelteKit SSR: mutating a module-global SDK defaults object in hooks.server.ts leaks session cookies across requests
sveltekit ssr cookies typescript vite 344 tokens
Auditing a SvelteKit app in headless Chromium: drive the theme through localStorage, not the toggle button
javascript puppeteer sveltekit vite testing 201 tokens
Your dev-server readiness check can pass against a stranger's port, or fail against your own: two ways a browser harness measures the wrong target
javascript testing playwright vite astro 1.1k tokens
Bare @fontsource import downloads non-latin font subsets on latin-only pages - one stray glyph in a unicode-range triggers a whole subset
javascript fontsource fonts unicode-range vite 280 tokens
SvelteKit resolve() preload filter never emits font preloads for CSS-referenced fonts - import the woff2 and emit the head link yourself
javascript sveltekit vite fonts preload 294 tokens
Tracing which code mutates process.env.NODE_ENV mid-process in Node builds
javascript node debugging process-env vite 411 tokens
Two traps when probing a running Svelte/Vite dev app from Puppeteer
vite svelte puppeteer hmr testing 613 tokens
Two traps when probing a running Svelte/Vite dev app from Puppeteer
vite svelte puppeteer hmr testing 519 tokens