> ## Documentation Index > Fetch the complete documentation index at: https://docs.mobster.dev/llms.txt > Use this file to discover all available pages before exploring further. # Checks after every Xcode build > Add one post-action to your Xcode scheme, and your checks run on each simulator build in the background, with the verdict as a notification. `mobster xcode hook` adds a post-action to your Xcode scheme. After each simulator build, from Xcode or `xcodebuild`, Mobster runs the checks of the app you built on that build, in the background. The verdict comes as a macOS notification. Xcode never waits for it. ## Turn it on From the folder with your `.xcodeproj` or `.xcworkspace`: ```sh theme={"theme":"css-variables"} mobster xcode hook --scheme YourApp --tag smoke ``` ```text theme={"theme":"css-variables"} Added the "Mobster checks" post-action to YourApp.xcodeproj/xcshareddata/xcschemes/YourApp.xcscheme. After each simulator build of YourApp, Mobster runs the checks of the app you built, in the background, and says the verdict in a notification. The log is .mobster/xcode/last.log. Commit the scheme to share it with your team. Take it out with: mobster xcode unhook --scheme YourApp ``` * The scheme has to be shared (Product › Scheme › Manage Schemes › Shared), so its file is in `xcshareddata`. * Mobster writes the scheme the way Xcode does, so your diff is the post-action's 19 lines. `mobster xcode unhook` takes them out, and the file is as it was. * `--tag smoke` runs only the checks tagged `smoke`. `--sim "iPhone 17 Pro"` runs them on that simulator instead of each check's own. ## What runs After the build, Xcode runs `mobster-agent xcode after-build --background`: 1. It reads the build from Xcode's settings (`BUILT_PRODUCTS_DIR`, `FULL_PRODUCT_NAME`, `PLATFORM_NAME`). A build for a device is skipped. 2. It picks the checks whose app is the one you built, by bundle ID, and points them at that build. 3. It returns at once, and the checks run in the background. A newer build stops the run an older build started. 4. The verdict comes as a notification, such as "3 passed". The log is in `.mobster/xcode/last.log`, the verdict in `.mobster/xcode/last.json`, and the full report in `.mobster/test-results/`. Launch-only checks make no model call, and checks with steps replay their recorded steps with no model once they've passed ([Replay and heals](/testing#replay-and-heals)). ## Use Mobster from Xcode's agents Xcode's Claude Agent and Codex read their own MCP servers from `~/Library/Developer/Xcode/CodingAssistant`, not from `~/.claude.json` or `~/.codex`. Those files only apply to agents you start in Xcode. One command writes Mobster into them: ```sh theme={"theme":"css-variables"} mobster mcp install xcode ``` ```text theme={"theme":"css-variables"} Mobster's MCP server: /Users/you/.local/bin/mobster mcp Xcode added ~/Library/Developer/Xcode/CodingAssistant/ClaudeAgentConfig/.claude.json Xcode added ~/Library/Developer/Xcode/CodingAssistant/codex/config.toml Restart Xcode to load the change. New sessions of the other clients pick it up. Check it with `mobster mcp doctor`. ``` * It keeps every other server and setting in both files, copies the old file to `.mobster-backup`, and changes nothing when you run it again. `--remove` takes only Mobster out. * Add `--with-skill` to put the Mobster skill in the Claude Agent's `skills` folder. * Xcode's Gemini folder is not written: its file format isn't documented. * The real iPhone path stays on your Mobster plan, as everywhere else. ### Use Xcode's tools and Mobster together Agents outside Xcode, such as Claude Code and Codex, reach Xcode through `xcrun mcpbridge`. One command adds it beside Mobster: ```sh theme={"theme":"css-variables"} mobster mcp install claude-code codex --with-xcode-tools ``` That runs `claude mcp add --scope user --transport stdio xcode -- xcrun mcpbridge` and `codex mcp add xcode -- xcrun mcpbridge`, the commands Apple documents. It needs Xcode 26.3 or later, and it leaves an existing `xcode` entry alone when that entry runs something else. Then: 1. In Xcode, choose Xcode › Settings › Intelligence and turn on "Allow external agents to use Xcode tools" under Model Context Protocol. Mobster never changes this setting. 2. Open your project in Xcode. `xcrun mcpbridge` connects to the running Xcode and exits with `no running Xcode processes found` when there is none. 3. Ask the agent: "Build the app, then check on a simulator that the paywall shows three plans." The agent builds with Xcode's tools, passes the `.app` to Mobster's `verify_start`, drives the simulator and answers with the verdict and its frames. Xcode's tools build, test and render previews. Mobster's tools run the built app, on a simulator or your iPhone, and the verdict comes from assertions on the accessibility tree, not from a model. ### What was run On 15 Oct 2026, on Xcode 26.4 with the iOS 26.4 simulator, with no Xcode window open: * `xcodebuild` built `examples/ios/Daybreak` for the simulator (`** BUILD SUCCEEDED **`) and `mobster verify --app … --keyless --text Daybreak` ran it on one simulator: verdict `passed`, 1 of 1 expectations held, 29.9 s including the simulator boot (25.3 s) and 0.8 s for the assertions. * `xcrun mcpbridge` with no Xcode running printed `MCP_XCODE_PID environment variable not set and no running Xcode processes found`. Not run: Xcode's own build tool through `mcpbridge`, and an agent started inside Xcode. Both need Xcode open and you signed in to Apple ID in Xcode. Xcode 27's agent plug-ins (a Mobster plug-in with a skill and MCP server) are not shipped: Xcode 27 isn't installed here, and whether plug-ins accept stdio servers isn't confirmed. This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.