fix(ios): iOS 27 DDI mount loops on Hangup failure (mount succeeds, cleanup rejected)

[maatheusgois-dd]

Summary

GADS v5.7.0 fails to set up iOS 27 (beta) devices. The DDI mount succeeds, but go-ios's trailing Hangup cleanup command fails because iOS 27 closes the mobile_image_mounter lockdown connection immediately after the mount. GADS treats this cleanup error as a fatal mount failure and resets the device in a ~12s retry loop, never reaching WDA.

Device

Field	Value
Device	iPhone 14 (iPhone14,7)
UDID	00008110-00040994117A602E
iOS	27.0 (27A5209h)
Xcode	26.3 (17C529)
GADS	v5.7.0
go-ios	v1.0.202

Error

Failed to mount Developer Disk Image (DDI) for device `00008110-00040994117A602E` - failed to mount DDI: MountImage: HangUp command failed: Write: only 0 bytes were written instead of 229

Repeats every ~12s in an infinite retry loop.

Root cause

The go-ios personalized DDI mount flow (personalized_image_mounter.go:67-130) is:

1. Query identifiers → get nonce → get Apple TSS signature
2. sendUploadRequest → stream DMG bytes → waitForUploadComplete
3. mountPersonalizedImage ← the actual mount; returns nil (succeeds)
4. hangUp ← sends {"Command":"Hangup"} over the same lockdown connection

On iOS 27, the device closes the mobile_image_mounter lockdown connection immediately after step 3 succeeds. Step 4's write gets 0 bytes → Write: only 0 bytes were written instead of 229 → wrapped as MountImage: HangUp command failed.

GADS's mountDeveloperImage() (provider/devices/ios.go:104) treats any non-"already mounted" error as fatal and calls resetWithError, which resets the device and triggers the retry loop — even though the DDI is already mounted.

This is not a lockdown-vs-CoreDevice protocol issue. The MountImage/Personalized plist command works; only the trailing Hangup is rejected. Xcode's devicectl uses CoreDevice and never sends Hangup, so it doesn't hit this.

Note: the latest go-ios (v1.0.218) adds a QueryPersonalizationManifest optimization but still sends the same Hangup — so bumping go-ios alone won't fix this.

Fix

When imagemounter.MountImage fails with "HangUp command failed", log a warning and re-connect to verify the DDI is mounted via ListImages. If an image is mounted, proceed to WDA. If verification fails, reset as before.

if strings.Contains(err.Error(), "HangUp command failed") {
    logger.ProviderLogger.LogWarn("ios_device_setup", ...)
    return d.verifyDDIMounted()
}

verifyDDIMounted opens a fresh NewImageMounter + ListImages on a new lockdown connection, independent of the closed mounter connection.

Verification

• go build ./provider/devices/ ✅
• go vet ./provider/devices/ ✅
• Live device verification not yet done — needs the iPhone 14 on iOS 27. The fix is testable by confirming setup proceeds past DDI mount to setupTunnelIfNeeded() → WDA install.

Related

• Bump go-ios dependency (currently v1.0.202) for iOS 26.x support #309 (go-ios bump for iOS 26.x) — related but distinct; this is an iOS 27-specific hangup-tolerance issue
• go-ios upstream: the hangUp call is at ios/imagemounter/imagemounter.go:180 (v1.0.202)