diff --git a/apps/antigravity/.antigravity-plugin/plugin.json b/apps/antigravity/.antigravity-plugin/plugin.json
new file mode 100644
index 00000000..8c96ebed
--- /dev/null
+++ b/apps/antigravity/.antigravity-plugin/plugin.json
@@ -0,0 +1,32 @@
+{
+  "name": "mobile-dev",
+  "displayName": "Mobile Dev",
+  "version": "0.1.0",
+  "description": "Stream iOS and Android devices beside your chat while building, running, or debugging mobile apps. Includes device control (agent-device), native and Metro logs, app storage inspection, and CPU, memory, and FPS performance profiling.",
+  "logo": "assets/icon.png",
+  "suggestedPrompts": [
+    "Open the iOS simulator or Android emulator beside this chat",
+    "Read the mobile app logs and help me fix the current error",
+    "Record CPU, memory, and FPS while I interact with the app"
+  ],
+  "author": {
+    "name": "Callstack",
+    "email": "hello@callstack.com",
+    "url": "https://www.callstack.com/"
+  },
+  "homepage": "https://github.com/callstackincubator/codex-mobile-dev-plugin",
+  "repository": "https://github.com/callstackincubator/codex-mobile-dev-plugin",
+  "license": "MIT",
+  "keywords": [
+    "mobile",
+    "ios",
+    "android",
+    "react-native",
+    "expo",
+    "simulator",
+    "emulator",
+    "profiling",
+    "performance",
+    "logs"
+  ]
+}
diff --git a/apps/antigravity/README.md b/apps/antigravity/README.md
new file mode 100644
index 00000000..ad0da691
--- /dev/null
+++ b/apps/antigravity/README.md
@@ -0,0 +1,54 @@
+# Mobile Dev for Antigravity
+
+Build, run, and debug iOS and Android apps without leaving Antigravity. Mobile Dev
+streams your simulators, emulators, and devices into an Antigravity Auxiliary Pane
+(`mobile-dev.device-panel`) beside the chat, and gives Antigravity the tools to
+control them, read their logs, inspect your app, and measure its performance. It
+works with Expo, React Native, SwiftUI, and other native mobile projects.
+
+- **Auxiliary Pane device panel:** a live, interactive iOS simulator, Android
+  emulator, or connected device in the Antigravity side pane, with logs and
+  performance tools beside it. Antigravity reads the devices you select there and the
+  logs, screenshots, and notes you add to chat.
+- **Device control and inspection:** Antigravity taps, types, scrolls, reads the
+  accessibility tree, and takes screenshots through the bundled
+  [agent-device](https://agent-device.dev/) runtime.
+- **App control:** install, launch, and stop apps, open deep links, send test pushes,
+  and set permissions and languages.
+- **App Flow:** a visual map of your app's screens and the navigation between them,
+  read from your Expo Router or React Navigation source and optionally captured by
+  walking the app on an iOS simulator.
+- **Logs:** iOS unified logs, Android logcat, physical iPhone logs, and Metro console
+  messages.
+- **Performance:** CPU, memory, and FPS recordings shown as interactive charts in
+  chat, which Antigravity can analyze and compare.
+- **App storage:** read what your app saved, such as UserDefaults, SharedPreferences,
+  AsyncStorage, MMKV, and SQLite, without adding code to it.
+- **Profile analysis:** TraceSift findings for local CPU and React profiles.
+
+## Install
+
+Package the Antigravity extension from this repository and install it with the `agy` CLI:
+
+```sh
+npm run build
+npm run package:antigravity
+agy plugin install ./release/antigravity-plugin/mobile-dev
+```
+
+Open the **Mobile Dev** icon in the Antigravity activity bar (Auxiliary Pane) or ask
+Antigravity to open your app on a simulator.
+
+## Requirements
+
+- An Apple Silicon Mac.
+- **Node.js 22.19 or later.** Mobile Dev looks for it on `PATH` and in the usual
+  Homebrew, nvm, fnm, Nix, Volta, mise, and asdf locations.
+- **iOS:** Xcode 26 or later with an installed simulator runtime. Physical iPhone
+  logs need Xcode 27 or later.
+- **Android:** Android SDK platform-tools and emulator, and an AVD or a device with
+  USB or wireless debugging authorized.
+
+## License
+
+MIT. See [LICENSE](LICENSE) and [third-party notices](THIRD_PARTY_NOTICES.md).
diff --git a/apps/antigravity/assets/icon.png b/apps/antigravity/assets/icon.png
new file mode 100644
index 00000000..ba1d10de
Binary files /dev/null and b/apps/antigravity/assets/icon.png differ
diff --git a/apps/antigravity/hooks.json b/apps/antigravity/hooks.json
new file mode 100644
index 00000000..e10db8bb
--- /dev/null
+++ b/apps/antigravity/hooks.json
@@ -0,0 +1,11 @@
+{
+  "mobile-dev-node-check": {
+    "SessionStart": [
+      {
+        "type": "command",
+        "command": "/bin/sh ./scripts/launch-node.sh --check",
+        "timeout": 10
+      }
+    ]
+  }
+}
diff --git a/apps/antigravity/mcp_config.json b/apps/antigravity/mcp_config.json
new file mode 100644
index 00000000..b8d47d22
--- /dev/null
+++ b/apps/antigravity/mcp_config.json
@@ -0,0 +1,11 @@
+{
+  "mcpServers": {
+    "mobile-dev": {
+      "command": "/bin/sh",
+      "args": [
+        "${PLUGIN_ROOT}/scripts/launch-node.sh",
+        "${PLUGIN_ROOT}/dist/server.mjs"
+      ]
+    }
+  }
+}
diff --git a/apps/antigravity/package.json b/apps/antigravity/package.json
new file mode 100644
index 00000000..b113e3d2
--- /dev/null
+++ b/apps/antigravity/package.json
@@ -0,0 +1,7 @@
+{
+  "name": "@mobile-dev/antigravity",
+  "version": "0.0.0",
+  "private": true,
+  "type": "module",
+  "description": "Antigravity: the Antigravity extension manifest and Auxiliary Pane sidecar for the shared server and MCP Apps panel."
+}
diff --git a/apps/antigravity/plugin-host.json b/apps/antigravity/plugin-host.json
new file mode 100644
index 00000000..27e91cfc
--- /dev/null
+++ b/apps/antigravity/plugin-host.json
@@ -0,0 +1,25 @@
+{
+  "label": "Antigravity",
+  "manifest": ".antigravity-plugin",
+  "mcpConfig": "mcp_config.json",
+  "hooks": "hooks.json",
+  "root": "PLUGIN_ROOT",
+  "config": {
+    "file": "antigravity-mcp-config.json",
+    "target": "~/.gemini/antigravity/mcp_config.json"
+  },
+  "panelRuntime": "download",
+  "build": "tooling/build.mjs",
+  "skills": [
+    "skills/mobile-dev",
+    "../../packages/skills/agent-device"
+  ],
+  "folders": [
+    "scripts",
+    "sidecars",
+    "mcp_config.json",
+    "hooks.json"
+  ],
+  "readme": "README.md",
+  "maxFileBytes": 5242880
+}
diff --git a/apps/antigravity/scripts/launch-node.sh b/apps/antigravity/scripts/launch-node.sh
new file mode 100755
index 00000000..62b819ce
--- /dev/null
+++ b/apps/antigravity/scripts/launch-node.sh
@@ -0,0 +1,44 @@
+#!/bin/sh
+# Runs Mobile Dev with Node.js 22.19 or later.
+#   launch-node.sh <script> [args]  runs the script with the first usable Node.
+#   launch-node.sh --check          prints a SessionStart hook result when none is found.
+# Claude starts plugin servers and hooks with the PATH it was launched with. Opened
+# from the Dock, that PATH usually lacks version managers, so also try their usual
+# install locations.
+set -u
+
+message="Mobile Dev needs Node.js 22.19 or later, and none was found on PATH or in Homebrew, nvm, fnm, Nix, Volta, mise or asdf locations. Install it, for example with 'brew install node' or from https://nodejs.org, then restart Claude."
+
+usable() {
+  [ -x "$1" ] && "$1" -e 'const [major, minor] = process.versions.node.split(".").map(Number); process.exit(major > 22 || (major === 22 && minor >= 19) ? 0 : 1)' >/dev/null 2>&1
+}
+
+candidates() {
+  command -v node
+  for directory in /opt/homebrew/bin /opt/homebrew/opt/node/bin /opt/homebrew/opt/node@24/bin /opt/homebrew/opt/node@22/bin /usr/local/bin \
+    "$HOME/.volta/bin" "$HOME/.local/share/mise/shims" "$HOME/.asdf/shims" \
+    "$HOME/.local/share/fnm/aliases/default/bin" "$HOME/Library/Application Support/fnm/aliases/default/bin" \
+    "$HOME/.nix-profile/bin" "/etc/profiles/per-user/${USER:-$(id -un)}/bin" /run/current-system/sw/bin /nix/var/nix/profiles/default/bin; do
+    echo "$directory/node"
+  done
+  for path in "$HOME"/.nvm/versions/node/*/bin/node "$HOME"/.local/share/mise/installs/node/*/bin/node \
+    "$HOME"/.local/share/fnm/node-versions/*/installation/bin/node "$HOME"/Library/Application\ Support/fnm/node-versions/*/installation/bin/node; do
+    echo "$path"
+  done
+}
+
+node=$(candidates 2>/dev/null | while IFS= read -r candidate; do
+  if [ -n "$candidate" ] && usable "$candidate"; then echo "$candidate"; break; fi
+done)
+
+if [ "${1:-}" = "--check" ]; then
+  [ -n "$node" ] && exit 0
+  printf '{"systemMessage":"%s","hookSpecificOutput":{"hookEventName":"SessionStart","additionalContext":"Mobile Dev tools are unavailable: Node.js 22.19 or later was not found. When the user asks for iOS or Android device work, explain this and offer to install Node.js (with Homebrew when brew is available, otherwise from https://nodejs.org), then ask them to fully restart Claude."}}\n' "$message"
+  exit 0
+fi
+
+if [ -z "$node" ]; then
+  echo "$message" >&2
+  exit 1
+fi
+exec "$node" "$@"
diff --git a/apps/antigravity/server/index.ts b/apps/antigravity/server/index.ts
new file mode 100644
index 00000000..767ecf58
--- /dev/null
+++ b/apps/antigravity/server/index.ts
@@ -0,0 +1,4 @@
+import "@mobile-dev/core/instrument";
+import { runServer } from "./server.ts";
+
+await runServer();
diff --git a/apps/antigravity/server/server.ts b/apps/antigravity/server/server.ts
new file mode 100644
index 00000000..f6a7dd9d
--- /dev/null
+++ b/apps/antigravity/server/server.ts
@@ -0,0 +1,39 @@
+import { mkdir, readFile, writeFile } from "node:fs/promises";
+import { homedir } from "node:os";
+import { dirname, join } from "node:path";
+import { browserPanel, createPanel, downloadedPanelRuntime, panelRuntimeReleaseSchema, runStdioServer, SharedTransport, usePanelRuntime } from "@mobile-dev/core";
+
+const pin = new URL("./panel-runtime.json", import.meta.url);
+usePanelRuntime(async () => {
+  const release = panelRuntimeReleaseSchema.parse(JSON.parse(await readFile(pin, "utf8")));
+  const runtime = downloadedPanelRuntime(release);
+  usePanelRuntime(runtime);
+  return runtime();
+});
+
+const stateFile = process.env.MOBILE_DEV_SIDECAR_STANDALONE === "1"
+  ? "antigravity-standalone.json"
+  : "antigravity-panel.json";
+const statePath = join(homedir(), "Library", "Caches", "mobile-dev", stateFile);
+
+async function writePanelState(url: string) {
+  try {
+    await mkdir(dirname(statePath), { recursive: true });
+    await writeFile(statePath, JSON.stringify({ pid: process.pid, url, updatedAt: Date.now() }) + "\n");
+  } catch {}
+}
+
+export async function runServer() {
+  await runStdioServer(transport => {
+    const connections = new SharedTransport(transport);
+    const panel = createPanel({ inline: false });
+    const features = [
+      browserPanel({
+        always: true,
+        onPage: writePanelState,
+        instructions: url => `Mobile Dev's panel is a page to show beside the chat, not in it. In Antigravity, the Mobile Dev Auxiliary Pane (sidecar "mobile-dev.device-panel") renders ${url} automatically; you can also surface a toggle pill for "mobile-dev.device-panel" or open ${url} if needed. The page shares the user's devices and what they add to chat through mobile_read_panel_context; read it before device work.`,
+      }),
+    ];
+    return { transport: connections, options: { panel, features, connections } };
+  });
+}
diff --git a/apps/antigravity/sidecars/device-panel/sidecar.json b/apps/antigravity/sidecars/device-panel/sidecar.json
new file mode 100644
index 00000000..e94ea1e9
--- /dev/null
+++ b/apps/antigravity/sidecars/device-panel/sidecar.json
@@ -0,0 +1,24 @@
+{
+  "command": "node",
+  "args": [
+    "../launch.mjs",
+    "device-panel"
+  ],
+  "env": {
+    "MOBILE_DEV_SIDECAR": "1"
+  },
+  "restart_policy": "always",
+  "display_name": "Mobile Dev",
+  "description": "Live iOS Simulator, Android Emulator, and physical iPhone panel with native/Metro logs, app storage inspection, and CPU, memory, and FPS profiling.",
+  "has_web_ui": true,
+  "ui_config": {
+    "display_name": "Mobile Dev",
+    "views": [
+      {
+        "title": "Mobile Dev",
+        "path": "/",
+        "entrypoint": "SIDECAR_UI_ENTRYPOINT_AUX_PANE"
+      }
+    ]
+  }
+}
diff --git a/apps/antigravity/sidecars/launch.mjs b/apps/antigravity/sidecars/launch.mjs
new file mode 100644
index 00000000..ec06aad7
--- /dev/null
+++ b/apps/antigravity/sidecars/launch.mjs
@@ -0,0 +1,239 @@
+import { spawn } from "node:child_process";
+import { readFile } from "node:fs/promises";
+import http from "node:http";
+import { homedir } from "node:os";
+import { dirname, join, resolve } from "node:path";
+import { fileURLToPath } from "node:url";
+
+const PORT = Number(process.env.ANTIGRAVITY_SIDECAR_WEB_PORT || 0);
+const TOKEN = process.env.ANTIGRAVITY_SIDECAR_TOKEN || "";
+const PLUGIN_ROOT = process.env.PLUGIN_ROOT || resolve(dirname(fileURLToPath(import.meta.url)), "..");
+const CACHE_DIR = join(homedir(), "Library", "Caches", "mobile-dev");
+const PANEL_STATE_FILE = join(CACHE_DIR, "antigravity-panel.json");
+const STANDALONE_STATE_FILE = join(CACHE_DIR, "antigravity-standalone.json");
+
+let standaloneChild = null;
+let startingBackend = null;
+
+function isPidAlive(pid) {
+  if (typeof pid !== "number" || pid <= 0) return false;
+  try {
+    process.kill(pid, 0);
+    return true;
+  } catch (error) {
+    return error?.code === "EPERM";
+  }
+}
+
+async function readValidState(filePath) {
+  try {
+    const raw = await readFile(filePath, "utf8");
+    const parsed = JSON.parse(raw);
+    if (typeof parsed?.url === "string" && isPidAlive(parsed.pid)) {
+      return parsed;
+    }
+  } catch {}
+  return null;
+}
+
+async function getActiveBackend() {
+  const mainState = await readValidState(PANEL_STATE_FILE);
+  if (mainState) {
+    if (standaloneChild && !standaloneChild.killed) {
+      try { standaloneChild.kill("SIGTERM"); } catch {}
+      standaloneChild = null;
+    }
+    return mainState;
+  }
+  return readValidState(STANDALONE_STATE_FILE);
+}
+
+async function ensureBackend() {
+  const existing = await getActiveBackend();
+  if (existing) return existing;
+
+  if (startingBackend) return startingBackend;
+
+  startingBackend = (async () => {
+    try {
+      if (!standaloneChild || standaloneChild.killed) {
+        const launchScript = join(PLUGIN_ROOT, "scripts", "launch-node.sh");
+        const serverScript = join(PLUGIN_ROOT, "dist", "server.mjs");
+        standaloneChild = spawn("/bin/sh", [launchScript, serverScript], {
+          env: {
+            ...process.env,
+            PLUGIN_ROOT,
+            MOBILE_DEV_SIDECAR_STANDALONE: "1",
+          },
+          stdio: ["pipe", "pipe", "pipe"],
+        });
+        standaloneChild.stdout?.resume();
+        standaloneChild.stderr?.resume();
+        standaloneChild.on("exit", () => {
+          standaloneChild = null;
+        });
+        // Send MCP initialize so the standalone stdio server stays open and starts its panel page.
+        const initRequest = JSON.stringify({
+          jsonrpc: "2.0",
+          id: 1,
+          method: "initialize",
+          params: {
+            protocolVersion: "2024-11-05",
+            capabilities: {},
+            clientInfo: { name: "antigravity-sidecar", version: "1.0.0" },
+          },
+        });
+        const initializedNotification = JSON.stringify({
+          jsonrpc: "2.0",
+          method: "notifications/initialized",
+        });
+        standaloneChild.stdin?.write(`${initRequest}\n${initializedNotification}\n`);
+      }
+
+      for (let i = 0; i < 40; i++) {
+        await new Promise(r => setTimeout(r, 200));
+        const state = await getActiveBackend();
+        if (state) return state;
+      }
+      return null;
+    } finally {
+      startingBackend = null;
+    }
+  })();
+
+  return startingBackend;
+}
+
+function parseCookies(cookieHeader) {
+  const cookies = {};
+  if (!cookieHeader) return cookies;
+  for (const pair of cookieHeader.split(";")) {
+    const idx = pair.indexOf("=");
+    if (idx > 0) {
+      const k = pair.slice(0, idx).trim();
+      const v = pair.slice(idx + 1).trim();
+      cookies[k] = decodeURIComponent(v);
+    }
+  }
+  return cookies;
+}
+
+function verifyRequestToken(req, urlObj) {
+  if (!TOKEN) return { valid: true, fromQuery: false };
+  const queryToken = urlObj.searchParams.get("token");
+  if (queryToken === TOKEN) return { valid: true, fromQuery: true };
+  const headerToken = req.headers["x-sidecar-token"];
+  if (headerToken === TOKEN) return { valid: true, fromQuery: false };
+  const cookies = parseCookies(req.headers.cookie);
+  if (cookies.antigravity_sidecar_token === TOKEN) return { valid: true, fromQuery: false };
+  return { valid: false, fromQuery: false };
+}
+
+function proxyHttpRequest(req, res, state, urlObj, setCookie) {
+  const panelUrl = new URL(state.url);
+  let targetPath = panelUrl.pathname;
+  if (urlObj.pathname === "/mcp") {
+    targetPath = `${panelUrl.pathname}mcp`;
+  } else if (urlObj.pathname === "/context") {
+    targetPath = `${panelUrl.pathname}context`;
+  } else if (urlObj.pathname === "/" || urlObj.pathname === "/index.html") {
+    targetPath = `${panelUrl.pathname}${panelUrl.search}`;
+  } else {
+    res.writeHead(404, { "Content-Type": "text/plain; charset=utf-8" });
+    res.end("Not Found");
+    return;
+  }
+
+  const headers = { ...req.headers };
+  headers.host = panelUrl.host;
+  headers.origin = panelUrl.origin;
+  delete headers.referer;
+
+  const proxyReq = http.request(
+    {
+      hostname: panelUrl.hostname,
+      port: Number(panelUrl.port),
+      path: targetPath,
+      method: req.method,
+      headers,
+    },
+    proxyRes => {
+      const resHeaders = { ...proxyRes.headers };
+      if (typeof resHeaders["content-security-policy"] === "string") {
+        resHeaders["content-security-policy"] = resHeaders["content-security-policy"].replace(/frame-ancestors\s+'none';?\s*/i, "");
+      }
+      if (setCookie && TOKEN) {
+        resHeaders["set-cookie"] = `antigravity_sidecar_token=${encodeURIComponent(TOKEN)}; Path=/; HttpOnly; SameSite=Lax`;
+      }
+      res.writeHead(proxyRes.statusCode || 200, resHeaders);
+      proxyRes.pipe(res);
+    },
+  );
+
+  proxyReq.on("error", err => {
+    if (!res.headersSent) {
+      res.writeHead(502, { "Content-Type": "text/plain; charset=utf-8" });
+    }
+    res.end(`Mobile Dev sidecar proxy error: ${err.message}`);
+  });
+
+  req.pipe(proxyReq);
+}
+
+const server = http.createServer(async (req, res) => {
+  try {
+    const urlObj = new URL(req.url || "/", `http://${req.headers.host || "127.0.0.1"}`);
+    const auth = verifyRequestToken(req, urlObj);
+    if (!auth.valid) {
+      res.writeHead(403, { "Content-Type": "text/plain; charset=utf-8" });
+      res.end("Forbidden: Invalid or missing Antigravity sidecar token.");
+      return;
+    }
+
+    if (urlObj.pathname === "/api/status") {
+      const state = await getActiveBackend();
+      res.writeHead(200, {
+        "Content-Type": "application/json; charset=utf-8",
+        "Cache-Control": "no-store",
+      });
+      res.end(JSON.stringify({
+        status: state ? "ok" : "starting",
+        pid: state?.pid ?? null,
+        updatedAt: state?.updatedAt ?? null,
+      }));
+      return;
+    }
+
+    const state = await ensureBackend();
+    if (!state) {
+      res.writeHead(503, { "Content-Type": "text/html; charset=utf-8", "Refresh": "2" });
+      res.end("<!doctype html><html><body style='font-family:system-ui;padding:24px;color:#888'>Starting Mobile Dev backend...</body></html>");
+      return;
+    }
+
+    proxyHttpRequest(req, res, state, urlObj, auth.fromQuery);
+  } catch (err) {
+    if (!res.headersSent) {
+      res.writeHead(500, { "Content-Type": "text/plain; charset=utf-8" });
+    }
+    res.end(`Internal Server Error: ${err.message}`);
+  }
+});
+
+server.listen(PORT, "127.0.0.1", () => {
+  const addr = server.address();
+  const actualPort = typeof addr === "object" && addr ? addr.port : PORT;
+  console.error(`[mobile-dev-sidecar] Listening on http://127.0.0.1:${actualPort}`);
+  ensureBackend().catch(() => {});
+});
+
+function shutdown() {
+  if (standaloneChild && !standaloneChild.killed) {
+    try { standaloneChild.kill("SIGTERM"); } catch {}
+  }
+  server.close(() => process.exit(0));
+  setTimeout(() => process.exit(0), 1000).unref();
+}
+
+process.on("SIGTERM", shutdown);
+process.on("SIGINT", shutdown);
diff --git a/apps/antigravity/skills/mobile-dev/SKILL.md b/apps/antigravity/skills/mobile-dev/SKILL.md
new file mode 100644
index 00000000..ac771edc
--- /dev/null
+++ b/apps/antigravity/skills/mobile-dev/SKILL.md
@@ -0,0 +1,38 @@
+---
+name: mobile-dev
+description: Use when building, running, changing, or debugging local iOS, Android, Expo, React Native, or SwiftUI apps in Antigravity. Renders Mobile Dev's device panel in the Antigravity Auxiliary Pane beside the chat, controls devices with Mobile Dev's device_* tools, reads native and Metro logs, and records CPU, memory, and FPS into interactive charts in chat. Skip web-only apps and tasks limited to planning, docs, or code review.
+---
+
+# Mobile Dev
+
+Mobile Dev shows the user's simulator, emulator, or physical iPhone in the Antigravity Auxiliary Pane (`mobile-dev.device-panel`) beside the chat, and gives you the tools to control apps on it, read its logs, and record its performance.
+
+Before calling a Mobile Dev tool that is not yet in your tool list, load it through your tool-search tool if your session uses deferred tools. If none of the `mobile_*` or `device_*` tools exist at all, read `references/missing-tools.md` to diagnose the plugin's Node.js startup.
+
+## Read the panel's context first
+
+The Auxiliary Pane does not push its selection into the chat on its own. Call `mobile_read_panel_context` before device work and whenever the user refers to "this screen", "these logs", a screenshot, or a device they selected:
+
+- It returns the active and visible device IDs from every open Mobile Dev panel, and any logs, screenshots, and screen notes the user clicked **Add to chat** on.
+- Pass the active device ID to your `mobile_*` and `device_*` calls so you act on the device the user is looking at.
+
+## Show the device panel when the user wants to see the app
+
+When the user asks to open a simulator, emulator, or device, run the app, or see a UI change:
+
+1. Call `mobile_open_simulator` with the platform (`ios` or `android`), or `mobile_open_workspace` when both platforms or no specific one is wanted. Pass `deviceId` when one is already known.
+2. In Antigravity, the Mobile Dev Auxiliary Pane (`mobile-dev.device-panel`) renders the panel beside the chat automatically. Do not open an external Chrome browser or launch a browser subagent for the panel URL. If the Auxiliary Pane is closed, you can surface a toggle pill for `mobile-dev.device-panel` using the `ui-plugin-navigation` skill.
+
+Never open the simulator backend's `baseUrl` (`127.0.0.1:46672`) or the `ui://mobile-dev/app.html` resource URI in a browser; neither is a standalone page.
+
+## Drive the app and verify UI changes
+
+Use the `agent-device` skill for `device_*` commands: `device_open`, `device_snapshot`, `device_click`, `device_fill`, `device_scroll`, `device_wait`, `device_screenshot`, and the rest. Use `mobile_install_app`, `mobile_launch_app`, `mobile_stop_app`, `mobile_open_url`, `mobile_set_app_permission`, `mobile_set_app_language`, and `mobile_send_push` for app lifecycle and system state.
+
+After a code change the user can see on screen, check it on the device and leave the app on the affected screen so they can see it in the panel.
+
+## Logs, storage, and performance
+
+- **Logs:** start `mobile_logs_session` with sources (`ios_Sim`, `android`, `ios_physical`, or `metro`), read with `mobile_read_logs`, and close with `mobile_logs_close` when done.
+- **App storage:** inspect UserDefaults, SharedPreferences, AsyncStorage, MMKV, Keychain, and SQLite with `mobile_app_storage`, `mobile_app_storage_table`, and `mobile_app_storage_file`.
+- **Performance:** record CPU, memory, and FPS with `mobile_record_performance`, finish with `mobile_finish_performance_recording`, and render or compare in chat with `mobile_render_performance_recording` and `mobile_compare_performance_recordings`. The chart renders in the chat; the device panel stays in the Auxiliary Pane.
diff --git a/apps/antigravity/skills/mobile-dev/references/missing-tools.md b/apps/antigravity/skills/mobile-dev/references/missing-tools.md
new file mode 100644
index 00000000..69a077b0
--- /dev/null
+++ b/apps/antigravity/skills/mobile-dev/references/missing-tools.md
@@ -0,0 +1,27 @@
+# Recover missing Mobile Dev tools
+
+Use this when the installed plugin's tools are unavailable. Diagnose and explain the
+setup problem in chat from the actual startup failure.
+
+Find the installed plugin root from the absolute path of the loaded `SKILL.md`: the
+skill is under `<plugin-root>/skills/mobile-dev/SKILL.md`. Inspect its
+`.antigravity-plugin/plugin.json` and `mcp_config.json`, and check whether the plugin
+is enabled in Antigravity. Use that installed copy rather than a source checkout or a
+guessed cache version.
+
+The server starts through `scripts/launch-node.sh`, which needs Node.js 22.19 or
+later and looks for it on `PATH` and in the usual Homebrew, nvm, fnm, Nix, Volta, mise and
+asdf locations. Run `/bin/sh "<plugin-root>/scripts/launch-node.sh" -p process.version`
+to see which Node it finds. If it reports that none was found, explain that Mobile
+Dev needs Node.js 22.19 or later and offer to install it: with `brew install node`
+when `brew` is available, otherwise from https://nodejs.org. Do not install it
+without the user's agreement. After the install, check the launcher again.
+
+Report the actual failure, or say what remains unknown. A generic timeout does not
+justify increasing the timeout. Keep diagnostics local; startup failures occur before
+the server's Sentry SDK starts.
+
+After resolving the startup failure, refresh MCP servers in Antigravity (or ask the
+user to restart Antigravity) so it can rediscover the server, then confirm the tools
+are available before resuming device work. Keep the original app task, and explain
+what remains blocked.
diff --git a/apps/antigravity/test/publish-release.test.ts b/apps/antigravity/test/publish-release.test.ts
new file mode 100644
index 00000000..9c658008
--- /dev/null
+++ b/apps/antigravity/test/publish-release.test.ts
@@ -0,0 +1,63 @@
+import assert from "node:assert/strict";
+import { execFileSync } from "node:child_process";
+import { mkdir, mkdtemp, readFile, rm, stat, writeFile } from "node:fs/promises";
+import { tmpdir } from "node:os";
+import { join } from "node:path";
+import { test, type TestContext } from "node:test";
+import { publishRelease } from "../tooling/publish-release.mjs";
+
+function git(directory: string, args: string[]) {
+  return execFileSync("git", args, { cwd: directory, encoding: "utf8", stdio: ["ignore", "pipe", "pipe"] });
+}
+
+async function fixture(t: TestContext) {
+  const directory = await mkdtemp(join(tmpdir(), "mobile-dev-antigravity-publish-test-"));
+  t.after(() => rm(directory, { recursive: true, force: true }));
+  const remote = join(directory, "remote.git");
+  const plugin = join(directory, "plugin");
+  git(directory, ["init", "--bare", remote]);
+  await mkdir(`${plugin}/.antigravity-plugin`, { recursive: true });
+  await mkdir(`${plugin}/sidecars/device-panel`, { recursive: true });
+  await mkdir(`${plugin}/dist/ios-fps`, { recursive: true });
+  await writeFile(`${plugin}/mcp_config.json`, '{"mcpServers":{}}');
+  await writeFile(`${plugin}/hooks.json`, '{"hooks":{}}');
+  await writeFile(`${plugin}/sidecars/device-panel/sidecar.json`, '{"id":"mobile-dev.device-panel"}');
+  await writeFile(`${plugin}/sidecars/launch.mjs`, "console.log('sidecar');\n");
+  await writeFile(`${plugin}/dist/server.mjs`, "console.log('server');\n");
+  await writeFile(`${plugin}/dist/ios-fps/mobile-dev-ios-fps`, "#!/bin/sh\n", { mode: 0o755 });
+  await writeFile(`${plugin}/dist/telemetry-environment.json`, '{"environment":"release"}');
+  await writeFile(`${plugin}/dist/app.html`, '<meta name="mobile-dev-environment" content="release">');
+  async function version(value: string, environment = "release") {
+    await writeFile(`${plugin}/dist/telemetry-environment.json`, JSON.stringify({ environment }));
+    await writeFile(`${plugin}/.antigravity-plugin/plugin.json`, JSON.stringify({
+      name: "mobile-dev", version: value, description: "Release fixture", author: { name: "Callstack", email: "hello@callstack.com" },
+    }));
+  }
+  async function checkout() {
+    const clone = join(directory, `clone-${Math.random().toString(36).slice(2)}`);
+    git(directory, ["clone", "--branch", "release/antigravity", remote, clone]);
+    return clone;
+  }
+  return { remote, plugin, version, checkout };
+}
+
+test("publishing puts the Antigravity extension beside its marketplace on release/antigravity", async t => {
+  const { remote, plugin, version, checkout } = await fixture(t);
+  await version("1.2.3");
+  assert.deepEqual(await publishRelease(plugin, "v1.2.3", remote), { published: true, version: "1.2.3", latest: "1.2.3" });
+  const clone = await checkout();
+  const catalog = JSON.parse(await readFile(join(clone, ".antigravity-plugin/marketplace.json"), "utf8"));
+  assert.equal(catalog.name, "mobile-dev");
+  assert.equal(JSON.parse(await readFile(join(clone, "mobile-dev/.antigravity-plugin/plugin.json"), "utf8")).version, "1.2.3");
+  assert.equal(JSON.parse(await readFile(join(clone, "mobile-dev/sidecars/device-panel/sidecar.json"), "utf8")).id, "mobile-dev.device-panel");
+  assert.equal((await stat(join(clone, "mobile-dev/dist/ios-fps/mobile-dev-ios-fps"))).mode & 0o111, 0o111);
+  assert.equal(git(clone, ["log", "-1", "--format=%s"]).trim(), "chore(release): release mobile-dev 1.2.3");
+});
+
+test("only a release build matching its tag is published", async t => {
+  const { remote, plugin, version } = await fixture(t);
+  await version("1.3.0");
+  await assert.rejects(publishRelease(plugin, "v1.2.9", remote), /must match the release tag/);
+  await version("1.3.0", "development");
+  await assert.rejects(publishRelease(plugin, "v1.3.0", remote), /requires a release build/);
+});
diff --git a/apps/antigravity/tooling/build.mjs b/apps/antigravity/tooling/build.mjs
new file mode 100644
index 00000000..4b20dc6b
--- /dev/null
+++ b/apps/antigravity/tooling/build.mjs
@@ -0,0 +1,17 @@
+import { copyFile } from "node:fs/promises";
+import { build } from "esbuild";
+import { serverBundleBanner } from "../../../tooling/server-bundle.mjs";
+
+export async function buildHost(outdir) {
+  await build({
+    entryPoints: ["apps/antigravity/server/index.ts"],
+    outfile: `${outdir}/server.mjs`,
+    bundle: true,
+    format: "esm",
+    platform: "node",
+    target: "node22",
+    sourcemap: "inline",
+    banner: { js: serverBundleBanner },
+  });
+  await copyFile("dist/browser-panel.html", `${outdir}/browser-panel.html`);
+}
diff --git a/apps/antigravity/tooling/publish-release.mjs b/apps/antigravity/tooling/publish-release.mjs
new file mode 100644
index 00000000..d19d96cb
--- /dev/null
+++ b/apps/antigravity/tooling/publish-release.mjs
@@ -0,0 +1,17 @@
+import { pluginMarketplace } from "../../../tooling/plugin-marketplace.mjs";
+import { publishFromCommandLine, publishPluginRelease } from "../../../tooling/release-branch.mjs";
+
+const release = {
+  manifestPath: ".antigravity-plugin/plugin.json",
+  requiredFiles: ["dist/server.mjs", "mcp_config.json", "hooks.json", "sidecars/device-panel/sidecar.json", "sidecars/launch.mjs"],
+  branch: "release/antigravity",
+  pluginPath: "mobile-dev",
+  catalogPath: ".antigravity-plugin/marketplace.json",
+  catalog: manifest => pluginMarketplace("mobile-dev", "Mobile Dev for Antigravity: iOS and Android device panel, control, logs, and performance charts.", manifest),
+};
+
+export function publishRelease(pluginDirectory, tag, remote, token) {
+  return publishPluginRelease(release, { pluginDirectory, tag, remote, token });
+}
+
+await publishFromCommandLine(import.meta.url, ({ pluginDirectory, tag, remote, token }) => publishRelease(pluginDirectory, tag, remote, token));
diff --git a/package-lock.json b/package-lock.json
index 7348b808..2d307166 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -14,6 +14,7 @@
         "packages/mcp-app",
         "packages/test-support",
         "apps/codex-plugin",
+        "apps/antigravity",
         "apps/claude",
         "apps/cursor",
         "apps/mac"
@@ -70,6 +71,10 @@
         "node": ">=22.19.0"
       }
     },
+    "apps/antigravity": {
+      "name": "@mobile-dev/antigravity",
+      "version": "0.0.0"
+    },
     "apps/claude": {
       "name": "@mobile-dev/claude",
       "version": "0.0.0"
@@ -1989,6 +1994,10 @@
         }
       }
     },
+    "node_modules/@mobile-dev/antigravity": {
+      "resolved": "apps/antigravity",
+      "link": true
+    },
     "node_modules/@mobile-dev/claude": {
       "resolved": "apps/claude",
       "link": true
diff --git a/package.json b/package.json
index afbba047..934e79ec 100644
--- a/package.json
+++ b/package.json
@@ -9,6 +9,7 @@
     "packages/mcp-app",
     "packages/test-support",
     "apps/codex-plugin",
+    "apps/antigravity",
     "apps/claude",
     "apps/cursor",
     "apps/mac"
@@ -48,6 +49,9 @@
     "test:ios-cpu": "node tooling/smoke-ios-cpu.mjs",
     "package": "node apps/codex-plugin/tooling/package.mjs",
     "package:release": "node apps/codex-plugin/tooling/package.mjs --release",
+    "antigravity:config": "node tooling/plugin-config.mjs antigravity",
+    "package:antigravity": "node tooling/package-plugin.mjs antigravity",
+    "test:antigravity": "node tooling/smoke-plugin.mjs antigravity",
     "claude:config": "node tooling/plugin-config.mjs claude",
     "package:claude": "node tooling/package-plugin.mjs claude",
     "test:claude": "node tooling/smoke-plugin.mjs claude",
diff --git a/packages/core/src/browser-panel.ts b/packages/core/src/browser-panel.ts
index 632816ad..1750af15 100644
--- a/packages/core/src/browser-panel.ts
+++ b/packages/core/src/browser-panel.ts
@@ -38,12 +38,20 @@ export type BrowserPanelOptions = {
    * server whose panel does not render inline (see createPanel's `inline`).
    */
   always?: boolean;
+  /** Called with the panel page URL when the server starts or opens the panel. */
+  onPage?: (url: string) => void | Promise<void>;
+  /** Customizes the instructions returned when a tool opens the panel page. */
+  instructions?: (url: string) => string;
 };
 
 /** Hosts without MCP Apps, or every host with `always`, can show the shared panel on a session-owned loopback page. */
-export function browserPanel({ template = PAGE, always = false }: BrowserPanelOptions = {}): ServerFeature {
+export function browserPanel({ template = PAGE, always = false, onPage, instructions: formatInstructions }: BrowserPanelOptions = {}): ServerFeature {
   return (server, { connections, onPanelOpen }) => {
     let page: Promise<PanelPage> | undefined;
+    if (onPage !== undefined && connections !== undefined) {
+      page = startPanelPage(connections, "other", template);
+      void page.then(opened => onPage(opened.url("mobile_open_simulator", {}))).catch(() => {});
+    }
     onPanelOpen(async ({ tool, target }) => {
       const capabilities = server.server.getClientCapabilities();
       if (connections === undefined || (always === false && getUiCapability(capabilities))) return;
@@ -52,7 +60,8 @@ export function browserPanel({ template = PAGE, always = false }: BrowserPanelOp
       page ??= startPanelPage(connections, host, template);
       const opened = await page;
       const url = opened.url(tool, target);
-      const instructions = `Mobile Dev's panel is a page to show beside the chat, not in it, and it is not open yet. Show it to the user now: open ${url} in your in-app browser or side panel, in the foreground, so the page is visible without another click. Opening a page can leave the browser pane hidden: when your host has a tool that brings its browser or preview pane into view, such as a show_pane tool for its preview pane, load it if needed and call it right after. Reuse a tab that already shows Mobile Dev. Open no other address for it, such as the backend's baseUrl. If you cannot open pages, give the user the link. The page shares the user's devices and what they add to chat through mobile_read_panel_context; read it before device work.`;
+      await onPage?.(url);
+      const instructions = formatInstructions?.(url) ?? `Mobile Dev's panel is a page to show beside the chat, not in it, and it is not open yet. Show it to the user now: open ${url} in your in-app browser or side panel, in the foreground, so the page is visible without another click. Opening a page can leave the browser pane hidden: when your host has a tool that brings its browser or preview pane into view, such as a show_pane tool for its preview pane, load it if needed and call it right after. Reuse a tab that already shows Mobile Dev. Open no other address for it, such as the backend's baseUrl. If you cannot open pages, give the user the link. The page shares the user's devices and what they add to chat through mobile_read_panel_context; read it before device work.`;
       return { url, instructions };
     });
     // A browser has no model context of its own, so the agent asks the server for it.
diff --git a/packages/core/src/panel-runtime.ts b/packages/core/src/panel-runtime.ts
index e3b3f070..739dab51 100644
--- a/packages/core/src/panel-runtime.ts
+++ b/packages/core/src/panel-runtime.ts
@@ -55,9 +55,10 @@ const STALE_MS = 60 * 60_000;
 const installed = /^\d+\.\d+\.\d+(?:-[\da-zA-Z.-]+)?-[0-9a-f]{12}$/;
 const run = promisify(execFile);
 
-/** The persistent folder for downloaded runtimes: the plugin's data folder in Claude Code, else the user's cache. */
+/** The persistent folder for downloaded runtimes: the plugin's data folder in the host, else the user's cache. */
 export function panelRuntimeDirectory(env: NodeJS.ProcessEnv = process.env) {
-  return env.CLAUDE_PLUGIN_DATA ? join(env.CLAUDE_PLUGIN_DATA, "panel-runtime") : join(homedir(), "Library", "Caches", "mobile-dev", "panel-runtime");
+  const data = env.CLAUDE_PLUGIN_DATA || env.PLUGIN_DATA;
+  return data ? join(data, "panel-runtime") : join(homedir(), "Library", "Caches", "mobile-dev", "panel-runtime");
 }
 
 /**
diff --git a/packages/core/test/browser-panel.test.ts b/packages/core/test/browser-panel.test.ts
index 25a705ea..5b7978e4 100644
--- a/packages/core/test/browser-panel.test.ts
+++ b/packages/core/test/browser-panel.test.ts
@@ -373,3 +373,33 @@ test("an oversized browser context update is refused without storing it", async
   assert.deepEqual(page.context(), []);
   await transport.terminateSession();
 });
+
+test("browserPanel notifies onPage on startup and when a panel tool runs, with custom instructions", async t => {
+  const directory = await mkdtemp(join(tmpdir(), "browser-panel-"));
+  const page = join(directory, "browser-panel.html");
+  await writeFile(page, "<html></html>");
+  const fake = await fakeBaguette();
+  const [hostSide, serverSide] = InMemoryTransport.createLinkedPair();
+  const shared = new SharedTransport(serverSide);
+  const seen: string[] = [];
+  const panel = createPanel({ baguette: new Baguette(fake.url), simulatorInput: fakeSimulatorInput(), inline: false });
+  const feature = browserPanel({
+    template: pathToFileURL(page),
+    always: true,
+    onPage: url => { seen.push(url); },
+    instructions: url => `Auxiliary Pane renders ${url} automatically.`,
+  });
+  const plugin = await createTestPlugin("<html></html>", { panel, features: [feature], connections: shared });
+  const host = new Client({ name: "antigravity-client", version: "1" });
+  await plugin.server.connect(shared);
+  await host.connect(hostSide);
+  t.after(async () => { await host.close(); await plugin.close(); await fake.close(); await rm(directory, { recursive: true, force: true }); });
+
+  await t.waitFor(() => assert.equal(seen.length, 1));
+  assert.equal(new URL(seen[0]).searchParams.get("tool"), "mobile_open_simulator");
+  const result = await host.callTool({ name: "mobile_open_workspace", arguments: {} });
+  assert.equal(seen.length, 2);
+  assert.equal(new URL(seen[1]).searchParams.get("tool"), "mobile_open_workspace");
+  const { browserPanel: opening } = result.structuredContent as { browserPanel: { url: string; instructions: string } };
+  assert.equal(opening.instructions, `Auxiliary Pane renders ${opening.url} automatically.`);
+});
diff --git a/packages/core/test/panel-runtime.test.ts b/packages/core/test/panel-runtime.test.ts
index 265834f6..38e60b73 100644
--- a/packages/core/test/panel-runtime.test.ts
+++ b/packages/core/test/panel-runtime.test.ts
@@ -137,7 +137,8 @@ test("a prerelease pins and installs its runtime like a release", async t => {
   assert.equal((await readdir(data)).length, 2);
 });
 
-test("Claude Code's plugin data folder holds the runtime when it provides one", () => {
+test("the host's plugin data folder holds the runtime when it provides one", () => {
   assert.equal(panelRuntimeDirectory({ CLAUDE_PLUGIN_DATA: "/data/mobile-dev" }), "/data/mobile-dev/panel-runtime");
+  assert.equal(panelRuntimeDirectory({ PLUGIN_DATA: "/data/antigravity" }), "/data/antigravity/panel-runtime");
   assert.match(panelRuntimeDirectory({}), /Library\/Caches\/mobile-dev\/panel-runtime$/);
 });
diff --git a/packages/mcp-app/src/browser-panel.ts b/packages/mcp-app/src/browser-panel.ts
index 3b8c6847..c50124fd 100644
--- a/packages/mcp-app/src/browser-panel.ts
+++ b/packages/mcp-app/src/browser-panel.ts
@@ -19,6 +19,8 @@ function notice(text: string) {
 /** A small MCP Apps host for the same shared panel the chat would otherwise render. */
 async function open() {
   const query = new URLSearchParams(location.search);
+  const sidecarToken = query.get("token");
+  const sidecarHeaders: Record<string, string> = sidecarToken ? { "x-sidecar-token": sidecarToken } : {};
   const toolName = query.get("tool") ?? "mobile_open_simulator";
   if (toolName !== "mobile_open_simulator" && toolName !== "mobile_open_workspace") {
     throw new Error("This link does not open a Mobile Dev panel.");
@@ -31,7 +33,11 @@ async function open() {
   const client = new Client({ name: "mobile-dev-browser-panel", version: PLUGIN_VERSION });
   const endpoint = new URL("mcp", location.href);
   const transport = new StreamableHTTPClientTransport(endpoint, {
-    fetch: (url, options) => fetch(url, { ...options, keepalive: options?.method === "DELETE" }),
+    fetch: (url, options) => fetch(url, {
+      ...options,
+      headers: sidecarToken ? { ...Object.fromEntries(new Headers(options?.headers).entries()), ...sidecarHeaders } : options?.headers,
+      keepalive: options?.method === "DELETE",
+    }),
   });
   let bridge: AppBridge | undefined;
   let heartbeat: ReturnType<typeof setInterval> | undefined;
@@ -53,6 +59,15 @@ async function open() {
   }
   function stopped(message: string) {
     if (disposed) return;
+    if (sidecarToken !== null && message === EXPIRED) {
+      const lastReload = Number(sessionStorage.getItem("mobile-dev-sidecar-reload") ?? "0");
+      if (Date.now() - lastReload > 3000) {
+        sessionStorage.setItem("mobile-dev-sidecar-reload", String(Date.now()));
+        dispose();
+        location.reload();
+        return;
+      }
+    }
     notice(message);
     dispose();
   }
@@ -108,7 +123,7 @@ async function open() {
       const sessionId = transport.sessionId;
       if (sessionId === undefined) throw new Error("Mobile Dev's browser connection is not ready.");
       const response = await fetch(new URL("context", location.href), {
-        method: "PUT", headers: { "content-type": "application/json", "mcp-session-id": sessionId },
+        method: "PUT", headers: { "content-type": "application/json", "mcp-session-id": sessionId, ...sidecarHeaders },
         body: JSON.stringify({ content: content ?? [] }),
       });
       if (response.status === 404) stopped(EXPIRED);
diff --git a/tooling/smoke-plugin.mjs b/tooling/smoke-plugin.mjs
index d1efc64f..92afa471 100644
--- a/tooling/smoke-plugin.mjs
+++ b/tooling/smoke-plugin.mjs
@@ -157,7 +157,8 @@ try {
   assert.equal(manifest.version, version);
   assert.equal(manifest.license, "MIT");
   await access(join(plugin, manifest.logo ?? manifest.icon));
-  const server = manifest.mcpServers["mobile-dev"];
+  const mcpConfig = host.mcpConfig ? JSON.parse(await readFile(join(plugin, host.mcpConfig), "utf8")) : manifest;
+  const server = mcpConfig.mcpServers["mobile-dev"];
   // The server runs with Node from PATH, or through the host's launcher, which also
   // finds Node where version managers install it.
   const launcher = server.command !== "node";
@@ -181,9 +182,10 @@ try {
   const PATH = `${dirname(process.execPath)}:/usr/bin:/bin:/usr/sbin:/sbin`;
   if (launcher) {
     // Its session check stays silent when Node is usable.
-    const hooks = JSON.parse(await readFile(join(plugin, "hooks/hooks.json"), "utf8"));
-    const [check] = hooks.hooks.SessionStart[0].hooks;
-    assert.equal(execFileSync("/bin/sh", ["-c", check.command], { env: { PATH, HOME: home, [host.root]: plugin }, encoding: "utf8" }), "");
+    const hooksPath = host.hooks ?? "hooks/hooks.json";
+    const hooks = JSON.parse(await readFile(join(plugin, hooksPath), "utf8"));
+    const [check] = hooks.hooks ? hooks.hooks.SessionStart[0].hooks : Object.values(hooks)[0].SessionStart;
+    assert.equal(execFileSync("/bin/sh", ["-c", check.command], { cwd: plugin, env: { PATH, HOME: home, [host.root]: plugin }, encoding: "utf8" }), "");
   }
   for (const environment of ["development", "release"]) {
     const env = { MOBILE_DEV_ENVIRONMENT: environment, [host.root]: plugin, ...launcher ? { PATH } : {} };