mara on PR #729: "this still feels hacky - is there a proper way to do this?"
damocles: agreed, "Accept-header map is meaningfully better than the
allowlist [...] one map definition that encodes browser semantics directly,
vs ~20 extensions to keep synced with whatever fluffychat (and any future
hyperhive-served SPA) decides to ship".
The previous shape (#684 catch-all regex, then this PR v1's
extension allowlist) leaned on heuristics to distinguish "missing
asset → 404" from "unknown SPA route → fall back to index.html".
Both shapes were fragile against a SPA shipping a new extension,
and the allowlist became dead code the moment a route ended in
`.html-ish-suffix`.
The proper distinction lives at the HTTP layer: top-frame browser
navigations send `Accept: text/html,...` (chrome/firefox/safari are
consistent on this). Asset fetches from script tags / img / fetch() /
XHR send asset-typed Accepts (`image/*`, `application/javascript`,
`*/*`) without `text/html`.
Mechanics: an `nginx http`-context `map` keyed on `$http_accept`
emits either `/matrix/index.html` (navigation) or a sentinel
nonexistent path (`/__matrix_spa_no_html_fallback`); the location's
`try_files $uri $uri/ $matrix_spa_target =404;` does the right thing
for both cases. No extension list, no regex narrowing, no `if` block,
no named-location fallback.
The `map` lives in `services.nginx.appendHttpConfig` (only added
when the matrix GUI is on, otherwise no `map` directive at all).
The location's `extraConfig` is now a single `try_files` line.
Verified via `nix eval` on both the rendered `appendHttpConfig` and
the location's `extraConfig`. Full closure build pending operator
deploy.
Closes#686.
68bac7986b