diff --git a/src/validation/index.ts b/src/validation/index.ts
index 01f8687..bc30700 100644
--- a/src/validation/index.ts
+++ b/src/validation/index.ts
@@ -18,3 +18,6 @@ export type { VisualJudgeInput, VisualJudgeResult } from "./visual-judge.js";
 
 export { discoverIosArtifact, discoverAndroidArtifact } from "./discover.js";
 export type { IosArtifact, AndroidArtifact } from "./discover.js";
+
+export { runStage1Visual } from "./stage1.js";
+export type { Stage1VisualInput, Stage1VisualResult } from "./stage1.js";
diff --git a/src/validation/stage1.ts b/src/validation/stage1.ts
new file mode 100644
index 0000000..652a72a
--- /dev/null
+++ b/src/validation/stage1.ts
@@ -0,0 +1,92 @@
+import { join } from "node:path";
+import { mkdir } from "node:fs/promises";
+import { discoverIosArtifact, discoverAndroidArtifact } from "./discover.js";
+import { runVisualJudge, DEFAULT_STAGE1_RUBRIC, type VisualJudgeResult } from "./visual-judge.js";
+import type { Layer3Criterion } from "./layer3.js";
+
+export type Stage1VisualInput = {
+  // Pre-built output dirs. Pass undefined to skip the platform.
+  iosDir?: string;
+  androidDir?: string;
+  // Where to write screenshots. Defaults to <cwd>/tmp/screenshots.
+  screenshotDir?: string;
+  spec: string;
+  rubric?: readonly Layer3Criterion[];
+  renderWaitMs?: number;
+  samplesPerCriterion?: number;
+};
+
+export type Stage1VisualResult = {
+  ios?: VisualJudgeResult;
+  android?: VisualJudgeResult;
+};
+
+// One-call convenience wrapper for the Stage 1 visual judge: discover the
+// pre-built artifact + identifier on each requested platform (#42), then run
+// the install → launch → capture → judge chain (#40, #41) for that platform.
+//
+// Returns a Stage1VisualResult shaped to match JudgeInput.visual's per-
+// platform expectation, so callers can pass it through to runJudge directly.
+//
+// Caller responsibilities:
+//   - Run Layer 2 in build mode first so the .app / .apk exists.
+//   - Ensure a sim/emulator is booted for each platform being judged.
+//   - Pick which platforms to judge — pass undefined for the others.
+export async function runStage1Visual(input: Stage1VisualInput): Promise<Stage1VisualResult> {
+  const screenshotDir = input.screenshotDir ?? join(process.cwd(), "tmp", "screenshots");
+  await mkdir(screenshotDir, { recursive: true });
+  const rubric = input.rubric ?? DEFAULT_STAGE1_RUBRIC;
+
+  const result: Stage1VisualResult = {};
+
+  if (input.iosDir) {
+    const ios = await discoverIosArtifact(input.iosDir);
+    if (ios) {
+      result.ios = await runVisualJudge({
+        platform: "ios",
+        artifactPath: ios.appPath,
+        bundleId: ios.bundleId,
+        screenshotPath: join(screenshotDir, "ios-home.png"),
+        spec: input.spec,
+        rubric,
+        ...(input.renderWaitMs !== undefined ? { renderWaitMs: input.renderWaitMs } : {}),
+        ...(input.samplesPerCriterion !== undefined ? { samplesPerCriterion: input.samplesPerCriterion } : {}),
+      });
+    } else {
+      result.ios = stubFailure("ios", "iOS artifact not discovered (run Layer 2 build mode first)");
+    }
+  }
+
+  if (input.androidDir) {
+    const android = await discoverAndroidArtifact(input.androidDir);
+    if (android) {
+      result.android = await runVisualJudge({
+        platform: "android",
+        artifactPath: android.apkPath,
+        packageName: android.packageName,
+        screenshotPath: join(screenshotDir, "android-home.png"),
+        spec: input.spec,
+        rubric,
+        ...(input.renderWaitMs !== undefined ? { renderWaitMs: input.renderWaitMs } : {}),
+        ...(input.samplesPerCriterion !== undefined ? { samplesPerCriterion: input.samplesPerCriterion } : {}),
+      });
+    } else {
+      result.android = stubFailure("android", "Android artifact not discovered (run Layer 2 build mode first)");
+    }
+  }
+
+  return result;
+}
+
+function stubFailure(platform: "ios" | "android", error: string): VisualJudgeResult {
+  return {
+    ok: false,
+    launch: {
+      ok: false,
+      command: `discover ${platform} artifact`,
+      durationMs: 0,
+      error,
+    },
+    error,
+  };
+}
diff --git a/tests/smoke.test.ts b/tests/smoke.test.ts
index fa9b515..872b12a 100644
--- a/tests/smoke.test.ts
+++ b/tests/smoke.test.ts
@@ -1,6 +1,6 @@
 import { test } from "node:test";
 import assert from "node:assert/strict";
-import { runLayer1, runLayer2, runLayer3, captureScreenshot, installAndLaunch, runVisualJudge, DEFAULT_STAGE1_RUBRIC, discoverIosArtifact, discoverAndroidArtifact } from "../src/validation/index.js";
+import { runLayer1, runLayer2, runLayer3, captureScreenshot, installAndLaunch, runVisualJudge, DEFAULT_STAGE1_RUBRIC, discoverIosArtifact, discoverAndroidArtifact, runStage1Visual } from "../src/validation/index.js";
 import { dispatch } from "../src/dispatch.js";
 
 test("validation layers are exported as functions", () => {
@@ -12,6 +12,25 @@ test("validation layers are exported as functions", () => {
   assert.equal(typeof runVisualJudge, "function");
   assert.equal(typeof discoverIosArtifact, "function");
   assert.equal(typeof discoverAndroidArtifact, "function");
+  assert.equal(typeof runStage1Visual, "function");
+});
+
+test("runStage1Visual returns structured failure when artifacts not built", async () => {
+  const result = await runStage1Visual({
+    iosDir: "/nonexistent/ios",
+    androidDir: "/nonexistent/android",
+    spec: "test",
+  });
+  assert.equal(result.ios?.ok, false);
+  assert.equal(result.android?.ok, false);
+  assert.match(result.ios?.error ?? "", /not discovered/i);
+  assert.match(result.android?.error ?? "", /not discovered/i);
+});
+
+test("runStage1Visual returns empty result when no platforms requested", async () => {
+  const result = await runStage1Visual({ spec: "test" });
+  assert.equal(result.ios, undefined);
+  assert.equal(result.android, undefined);
 });
 
 test("discoverAndroidArtifact returns null for missing dir", async () => {