diff --git a/CHANGELOG.md b/CHANGELOG.md
index 0526927c5..f70d80d42 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -12,6 +12,7 @@
 - Android: tapping the foreground service notification brings the app to the front. (#179) — thanks @Syhids
 - Cron tool passes `id` to the gateway for update/remove/run/runs (keeps `jobId` input). (#180) — thanks @adamgall
 - macOS: treat location permission as always-only to avoid iOS-only enums. (#165) — thanks @Nachx639
+- Onboarding: when running from source, auto-build missing Control UI assets (`pnpm ui:build`).
 
 ## 2026.1.4-1
 
diff --git a/src/commands/configure.ts b/src/commands/configure.ts
index 3bddae8e3..f35e03645 100644
--- a/src/commands/configure.ts
+++ b/src/commands/configure.ts
@@ -21,6 +21,7 @@ import {
 import { GATEWAY_LAUNCH_AGENT_LABEL } from "../daemon/constants.js";
 import { resolveGatewayProgramArguments } from "../daemon/program-args.js";
 import { resolveGatewayService } from "../daemon/service.js";
+import { ensureControlUiAssetsBuilt } from "../infra/control-ui-assets.js";
 import type { RuntimeEnv } from "../runtime.js";
 import { defaultRuntime } from "../runtime.js";
 import { resolveUserPath, sleep } from "../utils.js";
@@ -618,6 +619,11 @@ export async function runConfigureWizard(
     }
   }
 
+  const controlUiAssets = await ensureControlUiAssetsBuilt(runtime);
+  if (!controlUiAssets.ok && controlUiAssets.message) {
+    runtime.error(controlUiAssets.message);
+  }
+
   note(
     (() => {
       const bind = nextConfig.gateway?.bind ?? "loopback";
diff --git a/src/infra/control-ui-assets.test.ts b/src/infra/control-ui-assets.test.ts
new file mode 100644
index 000000000..f25db3cde
--- /dev/null
+++ b/src/infra/control-ui-assets.test.ts
@@ -0,0 +1,59 @@
+import fs from "node:fs/promises";
+import os from "node:os";
+import path from "node:path";
+
+import { describe, expect, it } from "vitest";
+
+import {
+  resolveControlUiDistIndexPath,
+  resolveControlUiRepoRoot,
+} from "./control-ui-assets.js";
+
+describe("control UI assets helpers", () => {
+  it("resolves repo root from src argv1", async () => {
+    const tmp = await fs.mkdtemp(path.join(os.tmpdir(), "clawdbot-ui-"));
+    try {
+      await fs.mkdir(path.join(tmp, "ui"), { recursive: true });
+      await fs.writeFile(
+        path.join(tmp, "ui", "vite.config.ts"),
+        "export {};\n",
+      );
+      await fs.writeFile(path.join(tmp, "package.json"), "{}\n");
+      await fs.mkdir(path.join(tmp, "src"), { recursive: true });
+      await fs.writeFile(path.join(tmp, "src", "index.ts"), "export {};\n");
+
+      expect(resolveControlUiRepoRoot(path.join(tmp, "src", "index.ts"))).toBe(
+        tmp,
+      );
+    } finally {
+      await fs.rm(tmp, { recursive: true, force: true });
+    }
+  });
+
+  it("resolves repo root from dist argv1", async () => {
+    const tmp = await fs.mkdtemp(path.join(os.tmpdir(), "clawdbot-ui-"));
+    try {
+      await fs.mkdir(path.join(tmp, "ui"), { recursive: true });
+      await fs.writeFile(
+        path.join(tmp, "ui", "vite.config.ts"),
+        "export {};\n",
+      );
+      await fs.writeFile(path.join(tmp, "package.json"), "{}\n");
+      await fs.mkdir(path.join(tmp, "dist"), { recursive: true });
+      await fs.writeFile(path.join(tmp, "dist", "index.js"), "export {};\n");
+
+      expect(resolveControlUiRepoRoot(path.join(tmp, "dist", "index.js"))).toBe(
+        tmp,
+      );
+    } finally {
+      await fs.rm(tmp, { recursive: true, force: true });
+    }
+  });
+
+  it("resolves dist control-ui index path for dist argv1", () => {
+    const argv1 = path.join("/tmp", "pkg", "dist", "index.js");
+    expect(resolveControlUiDistIndexPath(argv1)).toBe(
+      path.join("/tmp", "pkg", "dist", "control-ui", "index.html"),
+    );
+  });
+});
diff --git a/src/infra/control-ui-assets.ts b/src/infra/control-ui-assets.ts
new file mode 100644
index 000000000..e005789dc
--- /dev/null
+++ b/src/infra/control-ui-assets.ts
@@ -0,0 +1,147 @@
+import fs from "node:fs";
+import path from "node:path";
+
+import { runCommandWithTimeout, runExec } from "../process/exec.js";
+import { defaultRuntime, type RuntimeEnv } from "../runtime.js";
+
+export function resolveControlUiRepoRoot(
+  argv1: string | undefined = process.argv[1],
+): string | null {
+  if (!argv1) return null;
+  const normalized = path.resolve(argv1);
+  const parts = normalized.split(path.sep);
+  const srcIndex = parts.lastIndexOf("src");
+  if (srcIndex !== -1) {
+    const root = parts.slice(0, srcIndex).join(path.sep);
+    if (fs.existsSync(path.join(root, "ui", "vite.config.ts"))) return root;
+  }
+
+  let dir = path.dirname(normalized);
+  for (let i = 0; i < 8; i++) {
+    if (
+      fs.existsSync(path.join(dir, "package.json")) &&
+      fs.existsSync(path.join(dir, "ui", "vite.config.ts"))
+    ) {
+      return dir;
+    }
+    const parent = path.dirname(dir);
+    if (parent === dir) break;
+    dir = parent;
+  }
+
+  return null;
+}
+
+export function resolveControlUiDistIndexPath(
+  argv1: string | undefined = process.argv[1],
+): string | null {
+  if (!argv1) return null;
+  const normalized = path.resolve(argv1);
+  const distDir = path.dirname(normalized);
+  if (path.basename(distDir) !== "dist") return null;
+  return path.join(distDir, "control-ui", "index.html");
+}
+
+export type EnsureControlUiAssetsResult = {
+  ok: boolean;
+  built: boolean;
+  message?: string;
+};
+
+function summarizeCommandOutput(text: string): string | undefined {
+  const lines = text
+    .split(/\r?\n/g)
+    .map((l) => l.trim())
+    .filter(Boolean);
+  if (!lines.length) return undefined;
+  const last = lines.at(-1);
+  if (!last) return undefined;
+  return last.length > 240 ? `${last.slice(0, 239)}…` : last;
+}
+
+export async function ensureControlUiAssetsBuilt(
+  runtime: RuntimeEnv = defaultRuntime,
+  opts?: { timeoutMs?: number },
+): Promise<EnsureControlUiAssetsResult> {
+  const indexFromDist = resolveControlUiDistIndexPath(process.argv[1]);
+  if (indexFromDist && fs.existsSync(indexFromDist)) {
+    return { ok: true, built: false };
+  }
+
+  const repoRoot = resolveControlUiRepoRoot(process.argv[1]);
+  if (!repoRoot) {
+    const hint = indexFromDist
+      ? `Missing Control UI assets at ${indexFromDist}`
+      : "Missing Control UI assets";
+    return {
+      ok: false,
+      built: false,
+      message: `${hint}. Build them with \`pnpm ui:build\`.`,
+    };
+  }
+
+  const indexPath = path.join(repoRoot, "dist", "control-ui", "index.html");
+  if (fs.existsSync(indexPath)) {
+    return { ok: true, built: false };
+  }
+
+  const pnpmWhich = process.platform === "win32" ? "where" : "which";
+  const pnpm = await runExec(pnpmWhich, ["pnpm"])
+    .then(
+      (r) =>
+        r.stdout
+          .split(/\r?\n/g)
+          .map((l) => l.trim())
+          .find(Boolean) ?? "",
+    )
+    .catch(() => "");
+  if (!pnpm) {
+    return {
+      ok: false,
+      built: false,
+      message:
+        "Control UI assets not found and pnpm missing. Install pnpm, then run `pnpm ui:build`.",
+    };
+  }
+
+  runtime.log("Control UI assets missing; building (pnpm ui:build)…");
+
+  const ensureInstalled = !fs.existsSync(
+    path.join(repoRoot, "ui", "node_modules"),
+  );
+  if (ensureInstalled) {
+    const install = await runCommandWithTimeout([pnpm, "ui:install"], {
+      cwd: repoRoot,
+      timeoutMs: opts?.timeoutMs ?? 10 * 60_000,
+    });
+    if (install.code !== 0) {
+      return {
+        ok: false,
+        built: false,
+        message: `Control UI install failed: ${summarizeCommandOutput(install.stderr) ?? `exit ${install.code}`}`,
+      };
+    }
+  }
+
+  const build = await runCommandWithTimeout([pnpm, "ui:build"], {
+    cwd: repoRoot,
+    timeoutMs: opts?.timeoutMs ?? 10 * 60_000,
+  });
+  if (build.code !== 0) {
+    return {
+      ok: false,
+      built: false,
+      message: `Control UI build failed: ${summarizeCommandOutput(build.stderr) ?? `exit ${build.code}`}`,
+    };
+  }
+
+  if (!fs.existsSync(indexPath)) {
+    return {
+      ok: false,
+      built: true,
+      message: `Control UI build completed but ${indexPath} is still missing.`,
+    };
+  }
+
+  return { ok: true, built: true };
+}
diff --git a/src/wizard/onboarding.ts b/src/wizard/onboarding.ts
index 728474511..ca86475d3 100644
--- a/src/wizard/onboarding.ts
+++ b/src/wizard/onboarding.ts
@@ -45,6 +45,7 @@ import {
 import { GATEWAY_LAUNCH_AGENT_LABEL } from "../daemon/constants.js";
 import { resolveGatewayProgramArguments } from "../daemon/program-args.js";
 import { resolveGatewayService } from "../daemon/service.js";
+import { ensureControlUiAssetsBuilt } from "../infra/control-ui-assets.js";
 import type { RuntimeEnv } from "../runtime.js";
 import { defaultRuntime } from "../runtime.js";
 import { resolveUserPath, sleep } from "../utils.js";
@@ -491,6 +492,11 @@ export async function runOnboardingWizard(
     runtime.error(`Health check failed: ${String(err)}`);
   }
 
+  const controlUiAssets = await ensureControlUiAssetsBuilt(runtime);
+  if (!controlUiAssets.ok && controlUiAssets.message) {
+    runtime.error(controlUiAssets.message);
+  }
+
   await prompter.note(
     [
       "Add nodes for extra features:",