Mobile huddles disconnect on Auto-Lock; keep screen awake or support background calling

Describe the problem During a real team huddle on Buzz mobile for iPhone, the phone is allowed to auto-lock. Once the screen locks, the phone leaves the huddle even though the person did not choose Leave. This makes listening hands-free unreliable and looks like an unexpected disconnect.

This is a user-reported device observation. The lifecycle behavior below was verified against current upstream source; I have not independently reproduced screen locking on a physical phone.

Steps to reproduce

1. Join a team huddle in Buzz mobile, with another participant remaining connected.
2. Leave the app open and stop touching the screen while continuing the conversation/listening.
3. Let the phone's normal Auto-Lock timer lock the screen.
4. Observe the mobile participant leaving the huddle. Unlock and return to Buzz.

Manual screen lock and switching apps should also be included in regression testing, but the reported trigger is automatic lock.

Expected behavior An ongoing voice conversation should survive screen lock. If background calling remains outside the current MVP, prevent automatic screen sleep while a huddle is active and clearly explain that manually locking/backgrounding will leave the call. Restore normal screen behavior on every exit/failure/disposal path.

Version and platform

• Installed Buzz mobile version: 0.15.0, reported by the user; downloaded on 2026-09-17.
• Platform: iPhone (iOS). Exact iPhone model and iOS version are not yet known.
• Deployment: self-hosted community.
• Source checked: upstream main 4ab4f786085a23fe6126529861840eff6048ceee (2026-09-17). This is the investigated source revision, not a claim about the phone's installed build.

Source findings

• MobileHuddleController.build registers _leaveForBackground before relay pause and calls it on AppLifecycleState.paused or detached. _finishBackgroundLeave calls leave().
• Relay pause handling then disconnects the relay after its background grace period.
• Current iOS Info.plist has no UIBackgroundModes audio entry. The native media plugin uses a play-and-record voice-chat audio session, so simply removing the Dart leave callback would not be a complete, verified background-call fix.
• The merged mobile huddle MVP, #6056, explicitly scoped background calling out. This report requests a follow-up for the resulting Auto-Lock usability gap rather than assuming the foreground-only implementation was accidental.

Suggested validation Check automatic lock, manual lock, app switching, muted/listening-only participation, interruption/recovery, explicit leave and failed join on physical iOS/Android devices. Confirm participant membership and two-way audio, not just a surviving UI. If implementing a temporary keep-awake fix, verify it is released after all termination paths and never keeps the screen awake outside a call.

No exact matching open issue was found. #6511 concerns a desktop huddle ending after several minutes and appears distinct.