merge: complete bundle graph accounting

scripts/check-bundle.mjs

@@ -1,6 +1,7 @@
 import { readFile, writeFile } from "node:fs/promises";
 
 import { evaluateBundleBudget } from "../src/application/policies/performance-budgets.js";
+import { classifyViteJavascript } from "./lib/classify-vite-bundle.mjs";
 
 const report =
   /** @type {{
@@ -10,7 +11,7 @@ const report =
     JSON.parse(await readFile("artifacts/performance/bundle.json", "utf8"))
   );
 const viteManifest =
-  /** @type {Record<string, { file: string, isEntry?: boolean }>} */ (
+  /** @type {Record<string, { file: string, isEntry?: boolean, imports?: string[] }>} */ (
     JSON.parse(await readFile("dist/.vite/manifest.json", "utf8"))
   );
 const budgets =
@@ -21,24 +22,19 @@ const budgets =
 const outputByPath = new Map(
   report.outputs.map((output) => [output.path.replace(/^dist\//, ""), output]),
 );
-const initialFiles = new Set(
-  Object.values(viteManifest)
-    .filter((entry) => entry.isEntry)
-    .map((entry) => entry.file),
-);
-const lazyFiles = new Set(
-  Object.values(viteManifest)
-    .filter((entry) => !entry.isEntry && entry.file.endsWith(".js"))
-    .map((entry) => entry.file),
-);
-const initialJsGzipBytes = [...initialFiles].reduce(
+const classification = classifyViteJavascript(viteManifest);
+const initialJsGzipBytes = classification.initialFiles.reduce(
   (total, file) => total + (outputByPath.get(file)?.gzipBytes ?? 0),
   0,
 );
-const lazyChunks = [...lazyFiles].map((file) => ({
+const lazyChunks = classification.lazyFiles.map((file) => ({
   path: file,
   gzipBytes: outputByPath.get(file)?.gzipBytes ?? 0,
 }));
+const missingOutputs = [
+  ...classification.initialFiles,
+  ...classification.lazyFiles,
+].filter((file) => !outputByPath.has(file));
 const measurements = { initialJsGzipBytes, lazyChunks };
 const result = evaluateBundleBudget(measurements, budgets);
 const fixtures = [
@@ -70,10 +66,16 @@ const fixtures = [
       ).passed,
   },
 ];
-const passed = result.passed && fixtures.every((fixture) => fixture.passed);
+const passed =
+  result.passed &&
+  fixtures.every((fixture) => fixture.passed) &&
+  classification.missingImports.length === 0 &&
+  missingOutputs.length === 0;
 const completedReport = {
   ...report,
   measurements,
+  classification,
+  missingOutputs,
   thresholds: budgets,
   results: result,
   fixtures,
@@ -85,7 +87,12 @@ await writeFile(
   `${JSON.stringify(completedReport, null, 2)}\n`,
 );
 if (!passed) {
-  process.stderr.write("Bundle budget exceeded.\n");
+  process.stderr.write(
+    `Bundle budget or manifest integrity failed: ${[
+      ...classification.missingImports,
+      ...missingOutputs,
+    ].join(", ")}\n`,
+  );
   process.exit(1);
 }
 process.stdout.write(

scripts/lib/classify-vite-bundle.mjs

@@ -0,0 +1,49 @@
+/**
+ * @typedef {{
+ *   file: string,
+ *   isEntry?: boolean,
+ *   imports?: string[]
+ * }} ViteManifestEntry
+ */
+
+/**
+ * Static imports of an entry are part of initial JavaScript. Every remaining
+ * JavaScript output is governed by the lazy-chunk budget.
+ *
+ * @param {Record<string, ViteManifestEntry>} manifest
+ */
+export function classifyViteJavascript(manifest) {
+  const initialFiles = new Set();
+  const visitedKeys = new Set();
+  const pendingKeys = Object.entries(manifest)
+    .filter(([, entry]) => entry.isEntry)
+    .map(([key]) => key);
+  const missingImports = [];
+
+  while (pendingKeys.length > 0) {
+    const key = /** @type {string} */ (pendingKeys.pop());
+    if (visitedKeys.has(key)) continue;
+    visitedKeys.add(key);
+    const entry = manifest[key];
+    if (!entry) {
+      missingImports.push(key);
+      continue;
+    }
+    if (entry.file.endsWith(".js")) initialFiles.add(entry.file);
+    pendingKeys.push(...(entry.imports ?? []));
+  }
+
+  const allJavaScript = new Set(
+    Object.values(manifest)
+      .map((entry) => entry.file)
+      .filter((file) => file.endsWith(".js")),
+  );
+  const lazyFiles = [...allJavaScript].filter(
+    (file) => !initialFiles.has(file),
+  );
+  return Object.freeze({
+    initialFiles: Object.freeze([...initialFiles].sort()),
+    lazyFiles: Object.freeze(lazyFiles.sort()),
+    missingImports: Object.freeze(missingImports.sort()),
+  });
+}

tests/unit/bundle-classification.test.js

@@ -0,0 +1,40 @@
+import { describe, expect, it } from "vitest";
+
+import { classifyViteJavascript } from "../../scripts/lib/classify-vite-bundle.mjs";
+
+describe("Vite bundle classification", () => {
+  it("counts transitive static imports as initial and keeps dynamic chunks lazy", () => {
+    expect(
+      classifyViteJavascript({
+        "index.html": {
+          file: "assets/entry.js",
+          isEntry: true,
+          imports: ["_shared.js"],
+        },
+        "_shared.js": { file: "assets/shared.js", imports: ["_runtime.js"] },
+        "_runtime.js": { file: "assets/runtime.js" },
+        "src/lazy.js": { file: "assets/lazy.js" },
+      }),
+    ).toEqual({
+      initialFiles: [
+        "assets/entry.js",
+        "assets/runtime.js",
+        "assets/shared.js",
+      ],
+      lazyFiles: ["assets/lazy.js"],
+      missingImports: [],
+    });
+  });
+
+  it("reports a manifest import that cannot be resolved", () => {
+    expect(
+      classifyViteJavascript({
+        "index.html": {
+          file: "assets/entry.js",
+          isEntry: true,
+          imports: ["_missing.js"],
+        },
+      }).missingImports,
+    ).toEqual(["_missing.js"]);
+  });
+});