chore(mobile): drive dev-menu suppression from the dev-client launch URL

expo-dev-launcher 58 reads disableFab=1 and disableAutoLaunch=1 off the
manifest URL and updates the dev menu preferences before the app loads. The
showcase screenshot harness used to write those preferences straight into
the app container on both platforms; it now puts the flags on the launch
URL instead, keeping only the gesture toggles that have no URL form. The
mobile test skill mentions the flags for the same purpose.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

Author: juliusmarminge

.agents/skills/test-t3-mobile/SKILL.md

@@ -41,6 +41,9 @@ Start `vp run dev:client` from `apps/mobile`, or reuse a healthy Metro belonging
 to this checkout. Open its printed development-client URL with AgentDevice
 `open com.t3tools.t3code.dev <url>` and all returned target arguments.
 The device must be able to reach both Metro and the isolated backend.
+Append `&disableAutoLaunch=1&disableFab=1` to the development-client URL query
+when developer chrome would obscure screenshots or taps; the SDK 58 dev client
+applies these preferences before the app loads.
 
 ## Pair and verify
 

scripts/mobile-showcase.ts

@@ -33,6 +33,9 @@ const REPO_ROOT = NodePath.resolve(NodePath.dirname(NodeURL.fileURLToPath(import
 const MOBILE_ROOT = NodePath.join(REPO_ROOT, "apps/mobile");
 const ANDROID_PACKAGE = "com.t3tools.t3code";
 const APP_SCHEME = "t3code";
+// expo-dev-launcher reads these off the manifest URL and updates the dev menu
+// preferences before the app loads, keeping captures free of dev chrome.
+const DEV_CLIENT_LAUNCH_FLAGS = "disableOnboarding=1&disableFab=1&disableAutoLaunch=1";
 const IOS_READY_FILENAME = "T3ShowcaseReadyScene";
 const SERVER_HOST = "0.0.0.0";
 const IOS_SIMULATOR_ARCH = NodeProcess.arch === "arm64" ? "arm64" : "x86_64";
@@ -965,25 +968,9 @@ async function captureIos(
     await runCommand("xcrun", ["simctl", "install", simulator.udid, appPath]);
   }
 
-  for (const [key, value] of [
-    ["EXDevMenuIsOnboardingFinished", "true"],
-    ["EXDevMenuShowFloatingActionButton", "false"],
-    ["EXDevMenuShowsAtLaunch", "false"],
-  ] as const) {
-    await runCommand("xcrun", [
-      "simctl",
-      "spawn",
-      simulator.udid,
-      "defaults",
-      "write",
-      ANDROID_PACKAGE,
-      key,
-      "-bool",
-      value,
-    ]);
-  }
-
-  const metroUrl = `http://${metroHost}:${config.metroPort}?disableOnboarding=1`;
+  // The dev-client launch URL carries the dev menu preferences (SDK 58), so
+  // nothing is written into the app container ahead of launch.
+  const metroUrl = `http://${metroHost}:${config.metroPort}?${DEV_CLIENT_LAUNCH_FLAGS}`;
   const scenePath = NodePath.join(
     await iosAppContainer(simulator.udid),
     "Library/Caches/T3ShowcaseScene",
@@ -1191,12 +1178,12 @@ async function writeAndroidShowcaseScene(serial: string, scene: ShowcaseScene):
   ]);
 }
 
+// Gesture and key-command toggles have no launch-URL flag, so they still go
+// through the preferences file; onboarding, auto-launch and the floating button
+// come from DEV_CLIENT_LAUNCH_FLAGS on the launch URL.
 async function prepareAndroidShowcaseApp(serial: string): Promise<void> {
   const preferences = `<?xml version="1.0" encoding="utf-8" standalone="yes" ?>
 <map>
-  <boolean name="isOnboardingFinished" value="true" />
-  <boolean name="showsAtLaunch" value="false" />
-  <boolean name="showFab" value="false" />
   <boolean name="motionGestureEnabled" value="false" />
   <boolean name="touchGestureEnabled" value="false" />
   <boolean name="keyCommandsEnabled" value="false" />
@@ -1250,7 +1237,9 @@ async function captureAndroid(
   await runAdb(serial, ["shell", "pm", "clear", ANDROID_PACKAGE]);
   await prepareAndroidShowcaseApp(serial);
   await runAdb(serial, ["reverse", `tcp:${config.metroPort}`, `tcp:${config.metroPort}`]);
-  const metroUrl = encodeURIComponent(`http://127.0.0.1:${config.metroPort}?disableOnboarding=1`);
+  const metroUrl = encodeURIComponent(
+    `http://127.0.0.1:${config.metroPort}?${DEV_CLIENT_LAUNCH_FLAGS}`,
+  );
   const firstScene = capture.scenes[0] ?? "threads";
   await runAdb(serial, [
     "shell",