diff --git a/package.json b/package.json
index c5ca3238a..cf2779669 100644
--- a/package.json
+++ b/package.json
@@ -81,7 +81,7 @@
     "@ark/schema": "0.56.2"
   },
   "scripts": {
-    "setup": "bun install && bun run build:native && bun --cwd=packages/coding-agent link && sh scripts/link-omp.sh",
+    "setup": "bun scripts/setup.ts",
     "dev": "bun --cwd=packages/coding-agent src/cli.ts",
     "dev:timing": "PI_TIMING=x bun --cwd=packages/coding-agent --preload ../utils/src/module-timer.ts src/cli.ts",
     "stats": "bun --cwd=packages/coding-agent src/cli.ts stats",
diff --git a/scripts/bazel-natives.ts b/scripts/bazel-natives.ts
index 6183adc5e..8bb0f4c0b 100755
--- a/scripts/bazel-natives.ts
+++ b/scripts/bazel-natives.ts
@@ -136,6 +136,8 @@ export interface CliOptions {
 	dest: string | null;
 	source: string | null;
 	bazelArgs: string[];
+	/** Force the local Cargo/N-API host build path, skipping bazel. Same semantics as `OMP_NATIVE_BUILD_BACKEND=cargo`. */
+	cargo: boolean;
 }
 
 /** Parse target names and the mutually exclusive build or artifact source options. */
@@ -143,6 +145,7 @@ export function parseCliArgs(argv: string[]): CliOptions {
 	const targets: string[] = [];
 	let dest: string | null = null;
 	let source: string | null = null;
+	let cargo = false;
 	const bazelArgs: string[] = [];
 	for (let i = 0; i < argv.length; i++) {
 		const arg = argv[i];
@@ -160,6 +163,10 @@ export function parseCliArgs(argv: string[]): CliOptions {
 			}
 			continue;
 		}
+		if (arg === "--cargo") {
+			cargo = true;
+			continue;
+		}
 		if (arg.startsWith("-")) {
 			throw new Error(`Unknown flag ${arg} (extra bazel args go after \`--\`)`);
 		}
@@ -167,13 +174,19 @@ export function parseCliArgs(argv: string[]): CliOptions {
 	}
 	if (targets.length === 0) {
 		throw new Error(
-			"Usage: bun scripts/bazel-natives.ts <target>... [--dest <dir>] [--source <dir>] [-- <extra bazel args>]",
+			"Usage: bun scripts/bazel-natives.ts <target>... [--cargo] [--dest <dir>] [--source <dir>] [-- <extra bazel args>]",
 		);
 	}
 	if (source && bazelArgs.length > 0) {
 		throw new Error("--source cannot be combined with extra bazel arguments");
 	}
-	return { targets, dest, source, bazelArgs };
+	if (cargo && source) {
+		throw new Error("--cargo cannot be combined with --source");
+	}
+	if (cargo && bazelArgs.length > 0) {
+		throw new Error("--cargo cannot be combined with extra bazel arguments");
+	}
+	return { targets, dest, source, bazelArgs, cargo };
 }
 
 function resolveBazelBinary(): string | null {
@@ -246,7 +259,7 @@ async function main(): Promise<void> {
 	const host: HostInfo = { platform: process.platform, arch: process.arch, avx2: detectHostAvx2Support() };
 	const destDir = options.dest ? path.resolve(options.dest) : path.join(repoRoot, "packages/natives/native");
 
-	const cargoBackend = Bun.env.OMP_NATIVE_BUILD_BACKEND === "cargo";
+	const cargoBackend = options.cargo || Bun.env.OMP_NATIVE_BUILD_BACKEND === "cargo";
 	if ((host.platform === "win32" || cargoBackend) && !options.source) {
 		if (options.targets.length !== 1 || options.targets[0] !== "host") {
 			if (host.platform === "win32") {
@@ -256,7 +269,7 @@ async function main(): Promise<void> {
 						"(local napi build via VS Build Tools), or run this script from WSL/linux for cross targets.",
 				);
 			}
-			throw new Error("OMP_NATIVE_BUILD_BACKEND=cargo supports only the host target");
+			throw new Error("--cargo / OMP_NATIVE_BUILD_BACKEND=cargo supports only the host target");
 		}
 		await buildLocalHostAddon(host, destDir);
 		return;
diff --git a/scripts/setup.ts b/scripts/setup.ts
new file mode 100755
index 000000000..75c710585
--- /dev/null
+++ b/scripts/setup.ts
@@ -0,0 +1,62 @@
+#!/usr/bin/env bun
+/**
+ * `bun setup` entrypoint. Chains the four setup steps (install → native
+ * addon build → coding-agent link → omp link) and forwards a single UX flag:
+ *
+ *   --cargo   Build the host native addon via the local Cargo/N-API path
+ *             instead of bazel. Equivalent to
+ *             `OMP_NATIVE_BUILD_BACKEND=cargo` — surfaced as a flag because
+ *             bun/npm can't forward extra args past `&&`-chained scripts.
+ *
+ * Any other flags after `--` are appended to the native build invocation.
+ */
+import * as path from "node:path";
+
+const repoRoot = path.join(import.meta.dir, "..");
+
+const argv = process.argv.slice(2);
+let cargo = false;
+const passthrough: string[] = [];
+for (let i = 0; i < argv.length; i++) {
+	const arg = argv[i];
+	if (arg === "--") {
+		passthrough.push(...argv.slice(i + 1));
+		break;
+	}
+	if (arg === "--cargo") {
+		cargo = true;
+		continue;
+	}
+	passthrough.push(arg);
+}
+
+const nativeBackendEnv = cargo ? { OMP_NATIVE_BUILD_BACKEND: "cargo" } : {};
+
+interface Step {
+	label: string;
+	cmd: string[];
+	env?: Record<string, string>;
+	cwd?: string;
+}
+
+const steps: Step[] = [
+	{ label: "bun install", cmd: ["bun", "install"] },
+	{ label: "build:native", cmd: ["bun", "run", "build:native", ...passthrough], env: nativeBackendEnv },
+	{ label: "coding-agent link", cmd: ["bun", "--cwd=packages/coding-agent", "link"] },
+	{ label: "link omp", cmd: ["sh", "scripts/link-omp.sh"] },
+];
+
+for (const step of steps) {
+	console.log(`\n▶ ${step.label}`);
+	const proc = Bun.spawn(step.cmd, {
+		cwd: step.cwd ?? repoRoot,
+		env: { ...process.env, ...(step.env ?? {}) },
+		stdout: "inherit",
+		stderr: "inherit",
+	});
+	const exitCode = await proc.exited;
+	if (exitCode !== 0) {
+		console.error(`\nsetup step "${step.label}" failed (exit ${exitCode})`);
+		process.exit(exitCode || 1);
+	}
+}