diff --git a/.github/workflows/android-build.yml b/.github/workflows/android-build.yml
index aa51000..0295ca9 100644
--- a/.github/workflows/android-build.yml
+++ b/.github/workflows/android-build.yml
@@ -12,6 +12,9 @@ jobs:
     steps:
       - uses: actions/checkout@v4
 
+      - name: Validate dash-app manifests
+        run: node scripts/validate-manifests.js
+
       - name: Set up JDK 17
         uses: actions/setup-java@v4
         with:
diff --git a/scripts/validate-manifests.js b/scripts/validate-manifests.js
new file mode 100644
index 0000000..3660dfe
--- /dev/null
+++ b/scripts/validate-manifests.js
@@ -0,0 +1,82 @@
+"use strict";
+const fs = require("node:fs");
+const path = require("node:path");
+
+const SCHEMA_PATH = path.join(__dirname, "..", "docs", "dashapp-manifest.schema.json");
+const APPS_DIR = path.join(__dirname, "..", "dash-apps");
+
+const ROOT_KEYS = new Set(["$schema", "manifestVersion", "id", "perf", "settings"]);
+const PERF_KEYS = new Set(["gate", "reason", "root"]);
+const GATE_VALUES = new Set(["standard", "exempt"]);
+
+const schema = JSON.parse(fs.readFileSync(SCHEMA_PATH, "utf8"));
+const validSettings = new Set(schema.properties.settings.items.enum);
+const idRe = new RegExp(schema.properties.id.pattern);
+
+const dirs = fs.readdirSync(APPS_DIR).filter((name) => name.startsWith("web-"));
+if (dirs.length === 0) {
+  console.error("No dash-apps found in dash-apps/web-*/");
+  process.exit(1);
+}
+
+const errors = [];
+for (const folder of dirs) {
+  const manifestPath = path.join(APPS_DIR, folder, "manifest.json");
+  if (!fs.existsSync(manifestPath)) {
+    errors.push(`${folder}: missing manifest.json`);
+    continue;
+  }
+
+  const m = JSON.parse(fs.readFileSync(manifestPath, "utf8"));
+
+  for (const key of Object.keys(m)) {
+    if (!ROOT_KEYS.has(key)) errors.push(`${folder}: unknown property "${key}"`);
+  }
+  const expectedVersion = schema.properties.manifestVersion.const;
+  if (!Number.isInteger(m.manifestVersion) || m.manifestVersion !== expectedVersion) {
+    errors.push(`${folder}: manifestVersion must be ${expectedVersion}`);
+  }
+  if (typeof m.id !== "string" || !idRe.test(m.id)) {
+    errors.push(`${folder}: id must match ${schema.properties.id.pattern}`);
+  }
+  if (!Array.isArray(m.settings)) {
+    errors.push(`${folder}: settings must be an array`);
+  } else {
+    const seen = new Set();
+    for (const s of m.settings) {
+      if (!validSettings.has(s)) errors.push(`${folder}/settings: "${s}" is not a valid setting`);
+      if (seen.has(s)) errors.push(`${folder}/settings: "${s}" is duplicated`);
+      seen.add(s);
+    }
+  }
+
+  if (m.perf !== undefined) {
+    if (typeof m.perf !== "object" || m.perf === null) {
+      errors.push(`${folder}/perf: must be an object`);
+    } else {
+      for (const key of Object.keys(m.perf)) {
+        if (!PERF_KEYS.has(key)) errors.push(`${folder}/perf: unknown property "${key}"`);
+      }
+      if (m.perf.gate !== undefined && !GATE_VALUES.has(m.perf.gate)) {
+        errors.push(`${folder}/perf/gate: must be "standard" or "exempt"`);
+      }
+      if (m.perf.gate === "exempt" && (typeof m.perf.reason !== "string" || m.perf.reason.length < 10)) {
+        errors.push(`${folder}/perf/reason: required when gate is "exempt" (min 10 chars)`);
+      }
+    }
+  }
+
+  if (m.id !== undefined && typeof m.id === "string") {
+    const expectedFolder = `web-${m.id}`;
+    if (folder !== expectedFolder) {
+      errors.push(`${folder}: folder name does not match id "${m.id}" (expected "${expectedFolder}")`);
+    }
+  }
+}
+
+if (errors.length > 0) {
+  console.error(`Manifest validation failed:\n${errors.map((e) => `  - ${e}`).join("\n")}`);
+  process.exit(1);
+}
+
+console.log(`${dirs.length} dash-app manifests valid`);