refactor(core): single SelfPresence self-state builder

Core reconstructed PeerState in five command branches (join, mute
toggle, avatar change, screen-share start/stop), each repeating the full
field list. Factor a SelfPresence struct holding the sticky identity
fields (name + avatar) with a to_state(is_muted, addr, sharing) builder
that folds in the volatile per-announce fields, so the PeerState literal
lives in one place. This is the precondition for adding a broadcast
game-presence field without editing every call site.

No behavior change. +1 unit test (359 lib total path).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/network/mod.rs

@@ -41,6 +41,43 @@ pub struct PeerState {
     pub avatar: crate::avatar::Avatar,
 }
 
+/// The locally-owned, "sticky" pieces of our own presence: the identity fields
+/// that change only on explicit user action and persist for the whole core
+/// session. The remaining `PeerState` fields are *volatile* — mute state, current
+/// `addr`, and the active screen-share ticket are read fresh at each announce — so
+/// they are passed into [`SelfPresence::to_state`] rather than stored here.
+///
+/// This is the single source of truth for building our own `PeerState`: core
+/// reconstructs self-state in several command branches (join, mute toggle, avatar
+/// change, screen-share start/stop), and centralizing the `PeerState` literal here
+/// means a new presence field is added in exactly one place instead of at every
+/// call site.
+#[derive(Debug, Clone, Default)]
+pub struct SelfPresence {
+    pub name: String,
+    pub avatar: crate::avatar::Avatar,
+}
+
+impl SelfPresence {
+    /// Combine the sticky identity fields with the volatile per-announce fields
+    /// (`is_muted`, current `addr`, active-share `sharing` ticket) into a full
+    /// `PeerState` ready to announce over the gossip presence plane.
+    pub fn to_state(
+        &self,
+        is_muted: bool,
+        addr: iroh::EndpointAddr,
+        sharing: Option<String>,
+    ) -> PeerState {
+        PeerState {
+            name: self.name.clone(),
+            is_muted,
+            addr,
+            sharing,
+            avatar: self.avatar.clone(),
+        }
+    }
+}
+
 #[derive(Debug, Clone)]
 pub enum RoomEvent {
     PeerJoined(EndpointId, PeerState),
@@ -358,6 +395,27 @@ mod tests {
         assert_eq!(PeerSpeakTicket::restamp("not-a-ticket", EndpointAddr::from(me)), "not-a-ticket");
     }
 
+    #[test]
+    fn self_presence_builds_peer_state_with_volatile_fields() {
+        let addr = EndpointAddr::from(SecretKey::generate().public());
+        let presence = SelfPresence {
+            name: "Alice".to_string(),
+            avatar: crate::avatar::Avatar::default(),
+        };
+        // Volatile fields come from the call; sticky fields from the struct.
+        let muted = presence.to_state(true, addr.clone(), Some("ticket".to_string()));
+        assert_eq!(muted.name, "Alice");
+        assert!(muted.is_muted);
+        assert_eq!(muted.addr.id, addr.id);
+        assert_eq!(muted.sharing.as_deref(), Some("ticket"));
+        assert_eq!(muted.avatar, crate::avatar::Avatar::default());
+        // The same sticky presence yields different volatile fields per announce.
+        let unmuted = presence.to_state(false, addr.clone(), None);
+        assert!(!unmuted.is_muted);
+        assert_eq!(unmuted.sharing, None);
+        assert_eq!(unmuted.name, muted.name);
+    }
+
     #[test]
     fn test_peer_state_serde_round_trip() {
         let original = sample_peer_state();