Multi-device commands ignore device parameter on iOS 17+ physical devices

[partboost-coder]

Bug Description

When using multiple physical iOS 17+ devices, all MCP tool calls ignore the device parameter and route commands to the first device in the list instead of the specified device.

Environment

• mobile-mcp version: 0.0.39 and 0.0.40 (both affected)
• iOS version: 26.1 / 26.2 (iOS 17+ devices requiring go-ios tunnel)
• go-ios: Installed at /Users/matt/go/bin/ios
• Platform: macOS Darwin 24.6.0
• MCP SDK: @modelcontextprotocol/sdk

Steps to Reproduce

1. Connect multiple physical iOS 17+ devices
2. Verify devices are listed correctly:

mobile_list_available_devices
// Returns: iPad (00008132-...), iPad (2) (00008130-001202...), Cobra (00008130-001E0D...)

3. Send command to specific device:

mobile_open_url({ device: "00008130-001202823CC0001C", url: "https://example.com" })

4. Expected: URL opens on iPad (2)
5. Actual: URL opens on iPad (first device in list)

Evidence

When go-ios executes, it logs:

"no udid specified using first device in list"

This indicates mobile-mcp is NOT passing the device ID to go-ios when executing commands on physical iOS 17+ devices.

Tested Scenarios

Tool	Device Param	Expected Device	Actual Device
mobile_open_url	00008130-001202823CC0001C	iPad (2)	iPad
mobile_open_url	00008132-0012694E0EF9001C	iPad	iPad
mobile_open_url	00008130-001E0D802E42001C	Cobra	iPad
mobile_take_screenshot	00008130-001202823CC0001C	iPad (2)	iPad
mobile_list_elements_on_screen	00008130-001202823CC0001C	iPad (2)	iPad

All commands route to the same device regardless of the device parameter.

Workaround Attempted

• Pinning to version 0.0.39 (same issue)
• Adding explicit device selection via mobile_use_device tool (tool doesn't exist)
• Restarting go-ios tunnels (no effect)

Expected Behavior

The device parameter should be passed to go-ios so commands execute on the correct physical device.

Additional Context

• This was working on Jan 15, 2026 around 3:49 AM PST with @latest (which was 0.0.39 at the time)
• v0.0.40 was released Jan 15 at 7:18 PM PST
• Multi-device support may have regressed, or there's an intermittent issue with device session management

Suggested Fix

Ensure the device UDID is passed to go-ios when executing commands. The go-ios CLI accepts -u or --udid flag:

ios <command> --udid=<device-id>

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🔗 Related PRs

#241 - feat: move iphone-simulator calls to use mobilecli binary [merged]

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[gmegidish]

Hey @partboost-coder . Sorry for this bug. We're moving away from using go-ios directly, and instead will launch mobilecli (https://github.com/mobile-next/mobilecli) which incorporates go-ios within it. The purpose is that when mobilecli is launching webdriveragent, it remembers which local ports point to which remote device.

What happens right now, is that you have to set up the proxy yourself, and then mobile-mcp has no idea how to connect to the 2nd device. We're already done with the development, we're just checking a few things and it's almost out. We already migrated iOS Simulator code to be using mobilecli instead of assuming port 8090 is wda. You can already have 10 simulators running concurrently, and mobile-mcp will work with all of them at the same time.

We'll make a major version bump soon. Please drop by onto our Slack if you want to discuss further. I'd also be interested in hearing about your usecases.