diff --git a/package.json b/package.json
index 143b3e86..d39286b0 100644
--- a/package.json
+++ b/package.json
@@ -69,7 +69,8 @@
 		"publish-appbuilder": "bash scripts/build-appbuilder.sh 1 v1/main",
 		"publish-appbuilder-platform": "bash scripts/build-appbuilder.sh 1 app/builder/v1/main",
 		"publish": "bash scripts/build-appbuilder.sh 1",
-		"generate:mantine-props-zod": "node scripts/generate-mantine-props-zod.mjs"
+		"generate:mantine-props-zod": "node scripts/generate-mantine-props-zod.mjs",
+		"validate:settings": "node scripts/validate-settings-json.mjs"
 	},
 	"browserslist": {
 		"production": [
diff --git a/scripts/tsconfig.json b/scripts/tsconfig.json
new file mode 100644
index 00000000..ccf76396
--- /dev/null
+++ b/scripts/tsconfig.json
@@ -0,0 +1,12 @@
+{
+	"compilerOptions": {
+		"target": "ES2022",
+		"module": "ESNext",
+		"moduleResolution": "bundler",
+		"strict": true,
+		"noEmit": true,
+		"skipLibCheck": true,
+		"types": ["node"]
+	},
+	"include": ["validate-settings-json-runner.ts"]
+}
diff --git a/scripts/validate-settings-json-runner.ts b/scripts/validate-settings-json-runner.ts
new file mode 100644
index 00000000..b882fb7a
--- /dev/null
+++ b/scripts/validate-settings-json-runner.ts
@@ -0,0 +1,47 @@
+/**
+ * Fast settings JSON validation (no Jest). Used by validate-settings-json.mjs.
+ */
+import {readFileSync} from "node:fs";
+import process from "node:process";
+
+/** Minimal surface from appbuildertypecheck.ts (dynamic import). */
+interface AppBuilderTypecheckModule {
+	validateAppBuilderSettingsJson: (
+		value: unknown,
+	) => {success: true; data: unknown} | {success: false; error: unknown};
+	formatAppBuilderZodError: (error: unknown) => string;
+}
+
+const file = process.env.VALIDATE_SETTINGS_FILE;
+if (!file) {
+	console.error(
+		"validate-settings-json-runner: VALIDATE_SETTINGS_FILE not set",
+	);
+	process.exit(1);
+}
+
+const {formatAppBuilderZodError, validateAppBuilderSettingsJson} =
+	(await import(
+		import.meta
+			.resolve("../src/shared/features/appbuilder/config/appbuildertypecheck.ts")
+	)) as AppBuilderTypecheckModule;
+
+let json: unknown;
+try {
+	json = JSON.parse(readFileSync(file, "utf8"));
+} catch (error) {
+	console.error(
+		`Invalid JSON in ${file}: ${error instanceof Error ? error.message : String(error)}`,
+	);
+	process.exit(1);
+}
+
+const result = validateAppBuilderSettingsJson(json);
+if (!result.success) {
+	console.error(
+		`Settings JSON invalid (${file}):\n${formatAppBuilderZodError(result.error)}`,
+	);
+	process.exit(1);
+}
+
+console.log(`Settings JSON valid: ${file}`);
diff --git a/scripts/validate-settings-json.mjs b/scripts/validate-settings-json.mjs
new file mode 100644
index 00000000..c0744fb1
--- /dev/null
+++ b/scripts/validate-settings-json.mjs
@@ -0,0 +1,81 @@
+#!/usr/bin/env node
+/**
+ * Validate an App Builder settings JSON file (agent / CLI).
+ *
+ * Usage (from repo root):
+ *   pnpm run validate:settings -- public/my-config.json
+ *   node scripts/validate-settings-json.mjs public/my-config.json
+ *
+ * Fast path (~5–15s): tsx runner, no Jest. Times out after 30s.
+ * Exits 0 when valid, 1 when invalid, missing file, or timeout.
+ */
+
+import {spawn} from "node:child_process";
+import {existsSync} from "node:fs";
+import {createRequire} from "node:module";
+import {dirname, join, resolve} from "node:path";
+import process from "node:process";
+import {fileURLToPath} from "node:url";
+
+const repoRoot = join(dirname(fileURLToPath(import.meta.url)), "..");
+const RUNNER = join(repoRoot, "scripts/validate-settings-json-runner.ts");
+const TIMEOUT_MS = 30_000;
+
+const require = createRequire(join(repoRoot, "package.json"));
+const tsxCli = join(
+	dirname(require.resolve("tsx/package.json")),
+	"dist/cli.mjs",
+);
+
+function printUsage() {
+	console.error(`Usage: pnpm run validate:settings -- <path-to-json>
+
+Examples:
+  pnpm run validate:settings -- public/my-config.json
+  pnpm run validate:settings -- public/chair-brand.json
+
+Path is relative to the repo root or absolute.
+
+Do NOT run full pnpm test for single-file checks — use this command only.
+Expected runtime: under 30 seconds.`);
+}
+
+const arg = process.argv.slice(2).find((a) => a !== "--");
+
+if (!arg || arg === "--help" || arg === "-h") {
+	printUsage();
+	process.exit(arg ? 0 : 1);
+}
+
+const absPath = resolve(repoRoot, arg);
+
+if (!existsSync(absPath)) {
+	console.error(`validate-settings-json: file not found: ${absPath}`);
+	process.exit(1);
+}
+
+const childEnv = {...process.env, VALIDATE_SETTINGS_FILE: absPath};
+const child = spawn(process.execPath, [tsxCli, RUNNER], {
+	cwd: repoRoot,
+	env: childEnv,
+	stdio: "inherit",
+});
+
+const timer = setTimeout(() => {
+	console.error(
+		`\nvalidate-settings-json: timed out after ${TIMEOUT_MS / 1000}s — aborting.`,
+	);
+	child.kill("SIGTERM");
+	process.exit(1);
+}, TIMEOUT_MS);
+
+child.on("close", (code) => {
+	clearTimeout(timer);
+	process.exit(code === 0 ? 0 : 1);
+});
+
+child.on("error", (error) => {
+	clearTimeout(timer);
+	console.error(`validate-settings-json: failed to start: ${error.message}`);
+	process.exit(1);
+});