Both users starting a call in the same DM at once collapsed both attempts: two useSwitchOrStartDmCall instances (header outgoing + strip answer) race on the shared callEmbedAtom, the counter-ring surfaces during the outgoing embed's forming window, and answering it disposes+recreates the embed — putting two MembershipManagers on one (user,device) state-key, driving the SDK 'Missing own membership: force re-join' thrash. Fix per MatrixRTC canon (a call is co-presence, there is no 'answer'): a formingCallRoomIdAtom set synchronously before the outgoing awaits marks the room as forming; an incoming call for a room we already hold/are forming becomes a no-op (element-x model), the counter-ring is suppressed while forming, and the native-answer consumer won't tear down our forming call. Root + design from the internal research workflow. Not yet validated on device.
android.md: minSdk 26 correction + a Calls (Telecom) orientation section. telecom_migration.md: journal entry for the 2026-07-03 internal review — findings applied, the deferred set with rationale, and the on-device validation checklist.
