The non-Android branch of CallEngine::start loaded the seed from
\$HOME/.wzp/identity directly, while register_signal in lib.rs goes
through the shared load_or_create_seed() helper which resolves via
APP_DATA_DIR → Tauri's app_data_dir(). On macOS those are two
completely different files:
register_signal → ~/Library/Application Support/com.wzp.desktop/.wzp/identity
CallEngine::start (old) → ~/.wzp/identity
On a fresh install they end up holding two different random seeds.
Register and CallEngine then derive two different fingerprints from
those seeds, and when a direct call comes in the relay routes it to
"you" under the register_signal fingerprint, but once CallEngine tries
to join the call-* room it advertises a DIFFERENT fingerprint — which
fails the call_registry ACL check on the relay side (only the two
authorised participants of a call can join its room). Silent hang, the
call never completes.
Android hit this bug earlier in the week and was fixed by switching
its CallEngine::start branch to `crate::load_or_create_seed()`.
Backport the same single-line change to the desktop branch so both
platforms share one identity source of truth.
Also bring the desktop branch up to parity with the android branch on
diagnostic logging:
- log CallEngine::start entry with relay/room/alias/quality/has_reuse
- log endpoint.local_addr on reuse / create
- log "QUIC connection established, performing handshake" between
connect() and perform_handshake() so a hang at either step is
immediately localisable
- map_err all three potential failure points (create_endpoint,
connect, perform_handshake) to an explicit error! trace