README: document v0.4 symmetric presence chirp design + bump status

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

README.md

@@ -1,10 +1,15 @@
 # tether
 
-Phone ↔ laptop clipboard relay. **v0.1 / MVP.**
+Phone ↔ laptop clipboard relay. **v0.3 — WebRTC P2P working.**
 
-Today this is an HTTP+SSE broadcast bus. The roadmap is what makes it
-interesting: WebRTC for true P2P, Sign in with Apple for cross-device
-identity, mDNS for same-LAN discovery, end-to-end encryption baked in.
+Today: an HTTP+SSE broadcast bus that also bootstraps WebRTC DataChannels
+between participants. Once paired, clipboard text flows direct
+peer-to-peer with DTLS encryption — the server never sees the payload.
+
+The roadmap is what makes it interesting: symmetric presence chirps for
+self-healing mesh discovery, Sign in with Apple for cross-device
+identity, mDNS for zero-config same-LAN discovery, file drop, system
+tray UX.
 
 ```
 phone (web UI)              tether-server                tether-client
@@ -50,13 +55,37 @@ the buttons.
 
 | Phase | What | Why |
 |---|---|---|
-| **v0.1 (now)** | HTTP+SSE relay, single broadcast bus | Prove the shape end-to-end |
-| v0.2 | mDNS service advertisement, QR pairing | Zero-config discovery |
-| v0.3 | WebRTC data channel (Pion) — clients negotiate P2P after seeing each other via the server's signaling | True low-latency E2E (DTLS) |
-| v0.4 | Sign in with Apple OAuth → stable `sub` ties multiple devices to one trust circle | Identity without account/password |
-| v0.5 | OS clipboard hook on client (read + write) — phone copy → laptop paste appears automatically | The actual Universal-Clipboard UX |
-| v0.6 | File drop (large blob over WebRTC), encrypted at-rest history | Snapdrop-like UX bundled in |
-| v1.0 | macOS / Windows clients, push notifications when off-network, packaged installers | Product |
+| ✅ v0.1 | HTTP+SSE relay, single broadcast bus | Prove the shape end-to-end |
+| ✅ v0.2 | `/metrics` endpoint, server-side observability | Latency/throughput visibility |
+| ✅ v0.3 | WebRTC DataChannel (Pion ↔ browser RTCPeerConnection), peer chirps offer until paired | True P2P with mandatory DTLS encryption |
+| **v0.4 (next)** | **Symmetric presence chirps** — every participant (peer, browser, future Mac) broadcasts `{type:"presence", from, role, capabilities}` every 10-15s. Lets peers/browsers self-discover, auto-upgrade SSE→RTC, detect dead participants via heartbeat timeout. Pairs N-way (mesh, not star). | Self-healing discovery without the "happen to be open at the right moment" timing trap of v0.3's single-direction chirp |
+| v0.5 | mDNS service advertisement + QR pairing | Zero-config same-LAN discovery |
+| v0.6 | Sign in with Apple OAuth → stable `sub` ties multiple devices to one trust circle | Identity without account/password |
+| v0.7 | OS clipboard hook on client (read + write) — phone copy → laptop paste appears automatically | The actual Universal-Clipboard UX (current v0.3 has *write* on receive; missing the *read* on local change) |
+| v0.8 | File drop (large blob over WebRTC), encrypted at-rest history | Snapdrop-like UX bundled in |
+| v0.9 | Mouse/keyboard handoff (Synergy-style) using the same authenticated peer set + DataChannel | Universal Control for the rest of us |
+| v1.0 | macOS / Windows tray UX, push notifications when off-network, packaged installers | Product |
+
+### Note on v0.4 presence chirps
+
+The current peer's "chirp every 5s while unpaired" only solves
+one-direction late-joining. The full pattern is **symmetric**:
+
+```
+Every participant emits:
+    {type: "presence", from: <peerID>, role: "peer" | "browser",
+     capabilities: ["clipboard", "filedrop", "cursor"], ts: …}
+every 10-15s on the bus.
+
+Maintains  Map<peerID, lastSeen> table on each side.
+- New peer presence seen by browser → wait for offer.
+- New browser presence seen by peer → post targeted offer.
+- After RTC opens → drop chirp rate to 60s "alive" heartbeats.
+- lastSeen > 30s → mark dead, restart discovery.
+```
+
+Once that's in, the system becomes properly mesh-shaped — N devices can
+all auto-pair, see each other in the UI, drop a file to any one, etc.
 
 ## Why E2E by default
 
@@ -73,14 +102,14 @@ privacy-respecting identity provider that returns a stable per-app
 subject ID. Devices that authenticate to the same `sub` are in the same
 trust circle automatically. No passwords, no per-app account.
 
-## What this isn't
+## What this isn't (yet)
 
-- Not a Snapdrop clone (no file drop yet)
-- Not KDE Connect (no OS integration yet)
-- Not Pushbullet (no server-side persistence)
-- Not yet WebRTC (v0.1 is HTTP relay)
+- Not a Snapdrop clone — no file drop (v0.8 roadmap)
+- Not KDE Connect — no system-wide integration on the laptop side beyond clipboard (v0.7+)
+- Not Pushbullet — server never sees data, no persistence
+- Not Universal Control — but the mouse/keyboard handoff is on the roadmap (v0.9)
 
-But the foundation is right.
+The foundation is right: bus → signaling → WebRTC → mesh → identity.
 
 ## License