diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index fbebe3dc..7fd02731 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -40,6 +40,9 @@ jobs:
       - name: Build both targets
         run: pnpm build:both
 
+      - name: Bundle size gate
+        run: pnpm bundle-size
+
       - name: Validate MF manifest
         run: |
           MANIFEST=$(find dist/remote -name "mf-manifest.json" | head -1)
diff --git a/package.json b/package.json
index 63b9ab40..9666130a 100644
--- a/package.json
+++ b/package.json
@@ -18,7 +18,8 @@
     "test": "vitest run",
     "test:coverage": "vitest run --coverage",
     "lint": "eslint \"src/**/*.{ts,tsx}\" --max-warnings 0",
-    "typecheck": "tsc --noEmit"
+    "typecheck": "tsc --noEmit",
+    "bundle-size": "node scripts/ci/bundle-size-gate.mjs"
   },
   "dependencies": {
     "@microsoft/signalr": "^10.0.0",
diff --git a/scripts/ci/bundle-size-gate.mjs b/scripts/ci/bundle-size-gate.mjs
new file mode 100644
index 00000000..fe2f40bb
--- /dev/null
+++ b/scripts/ci/bundle-size-gate.mjs
@@ -0,0 +1,88 @@
+/**
+ * Bundle-size gate for CI.
+ *
+ * Finds all .js files in dist/remote/static/js/, measures their gzip size,
+ * reports per-file and total, and fails if total exceeds the budget.
+ *
+ * Budgets:
+ *   - Total remote bundle: <= 2000 kB gzip
+ */
+
+import { readFileSync, readdirSync, statSync } from "node:fs";
+import { join } from "node:path";
+import { gzipSync } from "node:zlib";
+
+const BUDGET_TOTAL_KB = 2000;
+const JS_DIR = "dist/remote/static/js";
+
+function collectJsFiles(dir) {
+  const results = [];
+  let entries;
+  try {
+    entries = readdirSync(dir);
+  } catch {
+    return results;
+  }
+  for (const entry of entries) {
+    const full = join(dir, entry);
+    const stat = statSync(full, { throwIfNoEntry: false });
+    if (!stat) continue;
+    if (stat.isDirectory()) {
+      results.push(...collectJsFiles(full));
+    } else if (entry.endsWith(".js")) {
+      results.push(full);
+    }
+  }
+  return results;
+}
+
+const files = collectJsFiles(JS_DIR);
+
+if (files.length === 0) {
+  console.error(`No .js files found in ${JS_DIR}. Did the build run?`);
+  process.exit(1);
+}
+
+let totalGzip = 0;
+const rows = [];
+
+for (const file of files) {
+  const raw = readFileSync(file);
+  const gzipped = gzipSync(raw);
+  const gzipKB = gzipped.length / 1024;
+  totalGzip += gzipKB;
+  rows.push({ file: file.replace("dist/remote/", ""), rawKB: (raw.length / 1024).toFixed(1), gzipKB: gzipKB.toFixed(1) });
+}
+
+rows.sort((a, b) => parseFloat(b.gzipKB) - parseFloat(a.gzipKB));
+
+console.log("\n--- Bundle Size Report ---\n");
+console.log(
+  "File".padEnd(60) +
+  "Raw (kB)".padStart(12) +
+  "Gzip (kB)".padStart(12)
+);
+console.log("-".repeat(84));
+
+for (const r of rows) {
+  console.log(
+    r.file.padEnd(60) +
+    r.rawKB.padStart(12) +
+    r.gzipKB.padStart(12)
+  );
+}
+
+console.log("-".repeat(84));
+console.log(
+  "TOTAL".padEnd(60) +
+  "".padStart(12) +
+  totalGzip.toFixed(1).padStart(12)
+);
+console.log(`\nBudget: ${BUDGET_TOTAL_KB} kB gzip`);
+
+if (totalGzip > BUDGET_TOTAL_KB) {
+  console.error(`\nFAILED: Total gzip size ${totalGzip.toFixed(1)} kB exceeds budget of ${BUDGET_TOTAL_KB} kB`);
+  process.exit(1);
+} else {
+  console.log(`\nPASSED: ${totalGzip.toFixed(1)} kB / ${BUDGET_TOTAL_KB} kB budget`);
+}