13. /assets and /static are two different mounts

• Date: 2026-08-02
• Status: accepted
• Where it is written down: app.md §2.2; issue #5 §3.2, §5.5

Context

The page needs two kinds of static file: the application's own chrome (the stylesheet system and the hypermedia runtime) and the seam's built bundle. It would be simpler to serve both from one static tree. It would also make the deletability principle unfalsifiable, because a build without the seam would be a build without a stylesheet.

Decision

Two mounts, and the difference is the deletability principle in the URL space.

Route	What it is
GET /assets/{app.css,htmx.js}	the application's own chrome, compiled into the binary (internal/app/assets)
GET /static/{path...}	whatever static tree the host mounted; 404 when it mounted none

A build with no seam serves a complete, styled, interactive page.

Both are vendored rather than linked. The offline invariant is not only about bundles: an atlas opens on a machine with no network, forever, and a page that fetches its runtime from a CDN is a page that does not.

Consequences

• The 404 is asserted rather than tolerated — TestStaticWithoutASeam (internal/app/app_test.go) — which turns the difference into a check of the deletability principle rather than an unchecked absence. (It was first asserted by the harness's seam-assets waiver, archived on golden-reference.)
• The make static target copies only render/dist/app.js into the tree a host mounts. The stylesheet is deliberately not there: deleting the seam costs the page one script tag, not its chrome.
• The dev loop can reload the two independently — templates.Reload(fs.FS) and assets.Reload(fs.FS) for the application's own files, esbuild --watch for the seam.
• A host that hands over no static tree is a legitimate, tested configuration, which is what atlas serve is on a machine that never built the seam.