fix: make LANGUAGES use explicit strings, so it doesn't resolve to string, so the extension set must require all languages. (thanks @jacoobes)

src/components/header.tsx

@@ -6,7 +6,7 @@ import { useEditor } from "./editor-provider";
 import { EditorTabs } from "./editor-tabs";
 import { Button, buttonVariants } from "~/components/ui/button";
 import { SearchableSelect } from "./searchable-select";
-import { LANGUAGES, LANGUAGES_SET } from "~/utils/languages";
+import { LANGUAGES, LANGUAGES_SET, type LanguageName } from "~/utils/languages";
 import { THEME_MAP } from "~/utils/themes";
 import { SaveButton } from "./save-button";
 import { Icons } from "./icons";
@@ -16,7 +16,8 @@ function LanguageThemeControls() {
   const { activeTab, theme, updateActiveTabLanguage, setTheme } = useEditor();
 
   const setLanguage = (language: string) => {
-    if (LANGUAGES_SET.has(language)) updateActiveTabLanguage(language);
+    if (LANGUAGES_SET.has(language as LanguageName))
+      updateActiveTabLanguage(language as LanguageName);
   };
 
   return (

src/utils/languages.ts

@@ -88,6 +88,6 @@ const BUILTIN_LANGUAGE_NAMES = [
 ] as const;
 
 export const MONACO_LANGUAGES = [...BUILTIN_LANGUAGE_NAMES, sfm] as const;
-export const LANGUAGES = [...BUILTIN_LANGUAGE_NAMES, sfm.name] as const;
+export const LANGUAGES = [...BUILTIN_LANGUAGE_NAMES, "sfm"] as const;
 export const LANGUAGES_SET = new Set(LANGUAGES);
 export type LanguageName = (typeof LANGUAGES)[number];

src/utils/paste-tabs.ts

@@ -1,4 +1,4 @@
-import { LANGUAGES, LANGUAGES_SET, type LanguageName } from "~/utils/languages";
+import { LANGUAGES_SET, type LanguageName } from "~/utils/languages";
 
 export interface PasteTab {
   id: string;
@@ -7,59 +7,96 @@ export interface PasteTab {
   content: string;
 }
 
-export const LANGUAGE_EXTENSIONS: Record<LanguageName, string> = {
+export const LANGUAGE_EXTENSIONS = {
   text: "txt",
+  abap: "abap",
+  ada: "ada",
+  apl: "apl",
   asm: "s",
+  astro: "astro",
   bat: "bat",
+  bibtex: "bib",
+  blade: "blade.php",
   c: "c",
-  "c#": "cs",
-  "c++": "cpp",
+  clojure: "clj",
+  cobol: "cob",
   coffeescript: "coffee",
   "common-lisp": "lisp",
+  "c++": "cpp",
+  crystal: "cr",
+  "c#": "cs",
   css: "css",
+  d: "d",
+  dart: "dart",
   dax: "dax",
   diff: "diff",
+  elixir: "ex",
+  elm: "elm",
+  erlang: "erl",
   "f#": "fs",
+  gleam: "gleam",
+  go: "go",
   graphql: "graphql",
+  groovy: "groovy",
+  hack: "hack",
+  haskell: "hs",
+  haxe: "hx",
   html: "html",
+  java: "java",
   javascript: "js",
+  jinja: "jinja",
   json: "json",
   json5: "json5",
   jsx: "jsx",
+  julia: "jl",
+  kotlin: "kt",
   latex: "tex",
   log: "log",
+  lua: "lua",
   markdown: "md",
+  matlab: "m",
   mdx: "mdx",
   mermaid: "mmd",
+  mojo: "mojo",
+  nim: "nim",
+  nix: "nix",
+  ocaml: "ml",
+  pascal: "pas",
+  perl: "pl",
+  php: "php",
   powershell: "ps1",
+  prisma: "prisma",
+  purescript: "purs",
   python: "py",
   r: "r",
   razor: "cshtml",
   ruby: "rb",
   rust: "rs",
+  scala: "scala",
   scheme: "scm",
   scss: "scss",
   shellscript: "sh",
   solidity: "sol",
   sql: "sql",
+  svelte: "svelte",
+  swift: "swift",
   toml: "toml",
   tsx: "tsx",
   typescript: "ts",
+  typst: "typ",
+  v: "v",
   vb: "vb",
   vue: "vue",
   wasm: "wat",
   wolfram: "wl",
   xml: "xml",
   yaml: "yml",
+  zig: "zig",
   sfm: "sfm",
-};
+} as const satisfies Record<LanguageName, string>;
 
-export const LANGUAGE_TO_EXTENSION = Object.fromEntries(
-  LANGUAGES.map((language) => [
-    language,
-    LANGUAGE_EXTENSIONS[language] ?? language.toLowerCase(),
-  ]),
-) as Record<LanguageName, string>;
+export const LANGUAGE_TO_EXTENSION: Record<LanguageName, string> =
+  LANGUAGE_EXTENSIONS;
 
 const EXTENSION_TO_LANGUAGE = Object.fromEntries(
   Object.entries(LANGUAGE_TO_EXTENSION).map(([language, extension]) => [
@@ -110,9 +147,11 @@ export const normalizeTabs = (tabs: unknown) =>
         const fallbackTab = createEmptyTab(index + 1);
 
         const filename = candidate.filename?.trim() ?? fallbackTab.filename;
-        const language = LANGUAGES_SET.has(candidate.language ?? "")
-          ? (candidate.language ?? "")
-          : (inferLanguage(filename) ?? "text");
+        const rawLanguage = candidate.language ?? "";
+        const language: LanguageName =
+          rawLanguage !== "" && LANGUAGES_SET.has(rawLanguage as LanguageName)
+            ? (rawLanguage as LanguageName)
+            : (inferLanguage(filename) ?? "text");
 
         return [
           {