Brings iroh into the lib behind the `iroh-transport` feature (off by default, so
the UniFFI/xcframework/agent builds are byte-for-byte unchanged). When on,
core/src/iroh.rs's IrohTransport replaces the whole hand-rolled SSE/RTC/LAN stack:
- implements the existing Transport trait, emits the existing MeshEvents, so the
engine event loop and every client are untouched — the MeshEvent seam paying off
- iroh-gossip carries clipboard Messages + presence over a topic derived from the
room (sha256("tether:"+room)); iroh handles key-addressing, holepunch, relay
- bootstrap via TETHER_IROH_BOOTSTRAP env (v1 stopgap until the rendezvous lands)
Verified: `cargo run --features iroh-transport --example iroh_engine` → the real
Engine (unchanged Engine::new/start/send + MessageHandler) syncs a clipboard A→B,
E2E-decrypted, over gossip, with NO SSE/RTC/LAN/relay. Default build + default
examples stay clean; feature build is warning-free.
Remaining (roadmap M4): rendezvous for zero-config bootstrap, iroh-blobs for
files, make webrtc/mdns/reqwest optional for a lean iroh/wasm build, A/B vs the
legacy stack, then flip the feature default.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Patrick Ecord
b377a6708a
