fix: prevent matrix-js-sdk plugin load crash (#56273) (thanks @aquaright1)

* Fix matrix-js-sdk multiple entrypoint crash on plugin load

* test(matrix): cover runtime bundle import regression

* fix: prevent matrix-js-sdk plugin load crash (#56273) (thanks @aquaright1)

* fix: widen matrix-js-sdk bundle import guard (#56273) (thanks @aquaright1)

---------

Co-authored-by: Kenny Xie <kennyxie@Mac-mini-von-Kenny.local>
Co-authored-by: Ayaan Zaidi <hi@obviy.us>

src/plugin-sdk/index.bundle.test.ts

@@ -8,7 +8,28 @@ import { buildPluginSdkEntrySources, pluginSdkEntrypoints } from "./entrypoints.
 const require = createRequire(import.meta.url);
 const tsdownModuleUrl = pathToFileURL(require.resolve("tsdown")).href;
 const bundledRepresentativeEntrypoints = ["matrix-runtime-heavy"] as const;
-const bundledCoverageEntrySources = buildPluginSdkEntrySources(bundledRepresentativeEntrypoints);
+const matrixRuntimeCoverageEntries = {
+  "matrix-runtime-sdk": "extensions/matrix/src/matrix/sdk.ts",
+} as const;
+const bundledCoverageEntrySources = {
+  ...buildPluginSdkEntrySources(bundledRepresentativeEntrypoints),
+  ...matrixRuntimeCoverageEntries,
+};
+const bareMatrixSdkImportPattern = /(?:from|require|import)\s*\(?\s*["']matrix-js-sdk["']/;
+
+async function listBuiltJsFiles(rootDir: string): Promise<string[]> {
+  const entries = await fs.readdir(rootDir, { withFileTypes: true });
+  const nested = await Promise.all(
+    entries.map(async (entry) => {
+      const entryPath = path.join(rootDir, entry.name);
+      if (entry.isDirectory()) {
+        return await listBuiltJsFiles(entryPath);
+      }
+      return entry.isFile() && entry.name.endsWith(".js") ? [entryPath] : [];
+    }),
+  );
+  return nested.flat();
+}
 
 describe("plugin-sdk bundled exports", () => {
   it("emits importable bundled subpath entries", { timeout: 120_000 }, async () => {
@@ -34,7 +55,9 @@ describe("plugin-sdk bundled exports", () => {
       },
       // Full plugin-sdk coverage belongs to `pnpm build`, package contract
       // guardrails, and `subpaths.test.ts`. This file only keeps the expensive
-      // bundler path honest across representative entrypoint families.
+      // bundler path honest across representative entrypoint families plus the
+      // Matrix SDK runtime import surface that historically crashed plugin
+      // loading when bare and deep SDK entrypoints mixed.
       entry: bundledCoverageEntrySources,
       env: { NODE_ENV: "production" },
       fixedExtension: false,
@@ -49,6 +72,21 @@ describe("plugin-sdk bundled exports", () => {
         await expect(fs.stat(path.join(outDir, `${entry}.js`))).resolves.toBeTruthy();
       }),
     );
+    await Promise.all(
+      Object.keys(matrixRuntimeCoverageEntries).map(async (entry) => {
+        await expect(fs.stat(path.join(outDir, `${entry}.js`))).resolves.toBeTruthy();
+      }),
+    );
+    const builtJsFiles = await listBuiltJsFiles(outDir);
+    const filesWithBareMatrixSdkImports = (
+      await Promise.all(
+        builtJsFiles.map(async (filePath) => {
+          const contents = await fs.readFile(filePath, "utf8");
+          return bareMatrixSdkImportPattern.test(contents) ? filePath : null;
+        }),
+      )
+    ).filter((filePath): filePath is string => filePath !== null);
+    expect(filesWithBareMatrixSdkImports).toEqual([]);
 
     // Export list and package-specifier coverage already live in
     // package-contract-guardrails.test.ts and subpaths.test.ts. Keep this file