app/lib/markdown-twin.ts

Functions

Imports

It imports app/lib/negotiate.mjs, app/lib/seo.ts. Imported by app/routes/blog.$slug.tsx, app/routes/blog.$slug[.md].ts, app/routes/content-page[.md].ts, app/routes/cv[.md].ts, app/routes/kb-library[.csv].ts, app/routes/kb-library[.json].ts, app/routes/kb-library[.md].ts, app/routes/lab[.md].ts, app/routes/llms-full[.txt].ts, app/routes/llms.ts, app/routes/procedure.version[.md].ts, app/routes/procedure[.md].ts, app/routes/protocols[.csv].ts, app/routes/protocols[.json].ts, app/routes/protocols[.md].ts, app/routes/publications.$slug[.md].ts, app/routes/systems[.md].ts.

Source

1import { prefersType } from "./negotiate.mjs";
2import { NO_STORE_CACHE_CONTROL, SITE_ORIGIN } from "./seo";
3
4export function linkToMarkdown(slug: string) {
5  return alternateMarkdownLink(`/writing/${slug}.md`);
6}
7
8/** `path` includes the `.md`. Absolute, so it matches the blog twin and `canonicalLink`. */
9function alternateMarkdownLink(path: string) {
10  return `<${SITE_ORIGIN}${path}>; rel="alternate"; type="text/markdown"`;
11}
12
13/**
14 * The `Link` header a machine-only document carries to name the HTML page it stands for: a post's
15 * twin names the post, llms.txt and llms-full.txt name the home page. Canonical, not alternate, so a
16 * crawler that reaches the twin first credits the page instead. The paper twins are assets and set the
17 * same header from public/_headers, where code cannot reach.
18 */
19export function canonicalLink(path: string) {
20  return `<${SITE_ORIGIN}${path}>; rel="canonical"`;
21}
22
23export function prefersMarkdown(request: Request) {
24  return prefersType(request, "text/markdown");
25}
26
27/**
28 * The negotiated `/writing/:slug` variant must never be stored: under `Vary: Accept, Cookie` a second
29 * stored variant lets a cookie-bearing request HIT the cookieless one, skipping the Worker's
30 * `private, no-store` downgrade. Do not "optimize" it to `SHARED_CACHE_CONTROL`.
31 */
32export function markdownResponse(slug: string, body: string, cacheControl: string) {
33  return new Response(body, {
34    headers: {
35      "content-type": "text/markdown; charset=utf-8",
36      "cache-control": cacheControl,
37      link: canonicalLink(`/writing/${slug}`),
38      // Only the never-stored response is the negotiated one, so only it varies on Accept.
39      ...(cacheControl === NO_STORE_CACHE_CONTROL ? { vary: "Accept" } : {}),
40    },
41  });
42}