test(media): gate the package core against fetch, Blob, File, URL, self and caches

frontend/media/eslint.config.js

@@ -28,6 +28,12 @@ const BROWSER_HOST = [
   "Worker",
   "VideoDecoder",
   "OffscreenCanvas",
+  "fetch",
+  "Blob",
+  "File",
+  "URL",
+  "self",
+  "caches",
 ];
 
 const NO_BROWSER_HOST =

tests/scripts/media_core_boundary.test.mjs

@@ -0,0 +1,77 @@
+// tests/scripts/media_core_boundary.test.mjs
+// Run with: pnpm test:scripts  (also part of the root `pnpm test`)
+//
+// `@visionset/media`'s core is the host-neutral half of the package: sampling policy and
+// grid arithmetic, with the browser decoder confined to `src/mediabunny/`. ESLint's
+// `no-restricted-globals` guards the same boundary; this text scan is the second gate,
+// the way `ui_core_boundary.test.mjs` backs ui-core. Type-level mentions of `Blob` and
+// `File` (`BlobLike`, `FileLike`) are legitimate and pass: only value uses are caught.
+import assert from "node:assert/strict";
+import { execFileSync } from "node:child_process";
+import { readFileSync } from "node:fs";
+import path from "node:path";
+import { fileURLToPath } from "node:url";
+import { test } from "node:test";
+
+const REPO = fileURLToPath(new URL("../../", import.meta.url));
+
+function coreSource() {
+  return execFileSync("git", ["ls-files", "frontend/media/src"], { cwd: REPO, encoding: "utf8" })
+    .split("\n")
+    .filter((file) => /\.[cm]?[jt]sx?$/.test(file))
+    .filter((file) => !/\.test\.[jt]sx?$/.test(file))
+    .filter((file) => !file.startsWith("frontend/media/src/mediabunny/"))
+    .map((file) => ({ path: file, text: readFileSync(path.join(REPO, file), "utf8") }));
+}
+
+const HOST_VALUES = [
+  [/\bfetch\s*\(/, "calls fetch — the host owns transport"],
+  [/\bnew\s+(?:Blob|File|Response|Request)\b/, "constructs a host Blob/File/Response/Request"],
+  [/\bURL\s*\.\s*(?:createObjectURL|revokeObjectURL|canParse)\b|\bnew\s+URL\b/, "uses the URL global"],
+  [/\bself\s*\./, "reaches the worker/window global through self"],
+  [/\bcaches\s*\./, "reaches the Cache Storage global"],
+  [/\b(?:globalThis|window)\s*\.\s*(?:fetch|Blob|File|URL|caches)\b/, "reaches a host global through globalThis"],
+];
+
+function violations(files, rules) {
+  const found = [];
+  for (const { path: file, text } of files) {
+    for (const [pattern, reason] of rules) {
+      if (pattern.test(text)) found.push(`${file}: ${reason}`);
+    }
+  }
+  return found;
+}
+
+test("the media core scans a non-empty source set", () => {
+  assert.ok(coreSource().some((file) => file.path === "frontend/media/src/index.ts"));
+});
+
+test("the media core reaches for no host transport or object global", () => {
+  assert.deepEqual(violations(coreSource(), HOST_VALUES), []);
+});
+
+test("the gate fires on a violation", () => {
+  const planted = [
+    'await fetch("/clip.mp4");\n',
+    "const b = new Blob([]);\n",
+    'const f = new File([], "a.mp4");\n',
+    "const u = URL.createObjectURL(b);\n",
+    'const u = new URL("x", base);\n',
+    "self.postMessage(1);\n",
+    'await caches.open("v");\n',
+    "const f = globalThis.fetch;\n",
+  ].map((text, i) => ({ path: `frontend/media/src/Bad${i}.ts`, text }));
+  for (const file of planted) {
+    assert.equal(violations([file], HOST_VALUES).length, 1, file.text);
+  }
+});
+
+test("the gate does NOT fire on the legitimate neighbouring form", () => {
+  const legitimate = [
+    { path: "frontend/media/src/ok.ts", text: "export interface BlobLike { size: number }\n" },
+    { path: "frontend/media/src/ok2.ts", text: "export interface FileLike extends BlobLike { name: string }\n" },
+    { path: "frontend/media/src/ok3.ts", text: "// the Blob surface, declared structurally\nconst prefetch = 1;\n" },
+  ];
+  assert.deepEqual(violations(legitimate, HOST_VALUES), []);
+});