Root-relative asset URLs ignore BASE_URL — myst-theme.css, favicon and the service-worker scope 404 on every page

[mmcky]

Every page on the deployed site requests several assets with root-relative URLs that omit the /lecture-wasm/ prefix, so they 404. Found while driving the site in a headless browser to validate QuantEcon/data-lectures#51.

One cause, four symptoms. The generated page head emits /-rooted hrefs while the site is served from BASE_URL=/lecture-wasm, and there is no <base> tag to rebase them — grep -c "<base " returns 0.

Requested	Result	Correct URL	Result
https://quantecon.github.io/myst-theme.css	404 (9115 B HTML error page)	/lecture-wasm/myst-theme.css	200, 36 bytes
https://quantecon.github.io/favicon.ico	404	/lecture-wasm/favicon.ico	200
skip-link target /french-rev#top	404	/lecture-wasm/french-rev#top	200
service worker scope https://quantecon.github.io/	registration fails	/lecture-wasm/service-worker.js	200

Sampled 10 pages: the root-relative /myst-theme.css appears on 10 of 10. Confirmed both from the served HTML and from document.styleSheets in the browser, which resolves it to https://quantecon.github.io/myst-theme.css.

Impact is small but non-zero

Worth being precise so this isn't over-prioritised. The correct myst-theme.css is a 36-byte placeholder — /* No Custom Stylesheet Provided */ — so there is no visual impact. What you get is console noise plus two wasted requests per page load (404 ×2 and net::ERR_ABORTED ×2, observed on french-rev/, / and cobweb/).

The service-worker one is different in kind: the browser reports Failed to register a ServiceWorker for scope ('https://quantecon.github.io/') with script ('…/service-worker.js?enableCache=false') while the correctly-prefixed script serves 200. JupyterLite registering at root scope rather than the site's base is worth checking separately — it may affect offline/caching behaviour rather than being purely cosmetic.

Not caused by the recent data migration

gh pr view 55 --json files shows #55 touched only lectures/french_rev.md and six dataset files. This is a pre-existing mystmd / quantecon-theme build behaviour.

Relationship to #42

Different cause, and they should not be conflated: #42 is the piplite warehouse 404 (/lecture-wasm/pypi/all.json), which fires on kernel start. These four fire on page load. Anyone opening the network tab sees several 404s at once and could easily read them as one problem.