Improve mesh relaying, presence, and DM robustness; signed public msgs; reachability UI; quicker announces; store-and-forward (#527)

* Sign public broadcasts; verify relayed messages via persisted signing keys; keep scheduled relays in sparse graphs and speed their jitter; persist announce signing key for offline auth; add short backoff after disconnect errors to reduce reconnect thrash

* Add connected vs reachable model: retain peers after link drop, expire after reachability window; expose all peers in snapshots; compute isReachable in UI; add meshReachable state and sorting; avoid removing peers on link events; notify UI on stale removals

* ContentView: handle new .meshReachable connection state in header icon switch (exhaustive switch fix)

* Logs: tag relayed announces as 'Reachable via mesh' and annotate public message logs with (direct|mesh) path for easier field analysis

* Fix syntax error: remove stray else/log inserted into writeOrEnqueue; keep logs clean

* UI: use 'point.3.connected.trianglepath.dotted' for mesh-reachable; change people count to include connected+reachable (exclude Nostr-only)

* UI: switch to 'point.3.filled.connected.trianglepath.dotted' for mesh-reachable icons in list and header

* Reachability: reduce retention to 21s for all peers (verified and unverified) to minimize stale presence

* mesh DMs/acks: route to reachable peers; queue READ/DELIVERED until handshake; add Transport.isPeerReachable; UI: hide offline non-mutuals; DM header: better name fallback + show transport + encryption icons; fix NostrTransport conformance

* Verification sheet: compute encryption status and fingerprint using short mesh ID mapping (fix 'not encrypted/handshake' for DMs with stable key)

* Announce cadence: faster discovery (4s), sparse 15±4s, dense 30±8s; initial 0.6s; post-subscribe 50ms; min-force 150ms; maintenance 5s; proactive announces on handshake + recent-traffic nudge

* Relay: increase broadcast TTL cap in sparse graphs to 6; tighten jitter for handshake (10–35ms) and directed (20–60ms) relays

* Range/robustness: store-and-forward for directed packets (15s) with flush on new links + periodic; announces: no subset + afterglow re-announce on first-seen; adaptive scanning: force ON when <=2 neighbors or recent traffic

* Fix warnings: remove unused msgID and unused mutable var in directed spool flush

* Announces: TTL 7 (sparse only) via RelayController; no fanout subset for announces; neighbor-change rebroadcast of last 2–3 announces. Fragments: faster pacing (5ms global, 4ms directed).

* Peer list: real-time icon updates by publishing snapshots on connectivity checks; add unread message indicator (envelope) next to peers with unread DMs

* UI: unread envelope uses orange; hasUnreadMessages checks Nostr conv key for peers with known Nostr pubkeys (geohash DM consistency)

* Logs/robustness: debounce disconnect notifications (1.5s), debounce 'reconnected' logs (2s), add weak-link cooldown after timeouts on very weak RSSI (<= -90)

* Peer icons: faster, accurate reachability\n\n- Run connectivity checks every maintenance tick (5s)\n- Publish peer snapshots on central unsubscribe for instant UI refresh\n- Lower inactivity timeout to 8s and disconnect debounce to 0.9s\n- Gate reachability on mesh-attached (>=1 direct link); no links => no reachable peers\n- Keep 21s retention for verified/unverified, but only when attached to mesh\n\nImproves list responsiveness when walking out of range and prevents stale 'reachable' states when isolated.

---------

Co-authored-by: jack <jackjackbits@users.noreply.github.com>

bitchat/Services/MessageRouter.swift

@@ -37,11 +37,11 @@ final class MessageRouter {
     }
 
     func sendPrivate(_ content: String, to peerID: String, recipientNickname: String, messageID: String) {
-        let hasMesh = mesh.isPeerConnected(peerID)
-        let hasEstablished = mesh.getNoiseService().hasEstablishedSession(with: peerID)
-        if hasMesh && hasEstablished {
-            SecureLogger.log("Routing PM via mesh to \(peerID.prefix(8))… id=\(messageID.prefix(8))…",
+        let reachableMesh = mesh.isPeerReachable(peerID)
+        if reachableMesh {
+            SecureLogger.log("Routing PM via mesh (reachable) to \(peerID.prefix(8))… id=\(messageID.prefix(8))…",
                             category: SecureLogger.session, level: .debug)
+            // BLEService will initiate a handshake if needed and queue the message
             mesh.sendPrivateMessage(content, to: peerID, recipientNickname: recipientNickname, messageID: messageID)
         } else if canSendViaNostr(peerID: peerID) {
             SecureLogger.log("Routing PM via Nostr to \(peerID.prefix(8))… id=\(messageID.prefix(8))…",
@@ -57,9 +57,9 @@ final class MessageRouter {
     }
 
     func sendReadReceipt(_ receipt: ReadReceipt, to peerID: String) {
-        // Prefer mesh only if a Noise session is established; else use Nostr to avoid handshakeRequired spam
-        if mesh.isPeerConnected(peerID) && mesh.getNoiseService().hasEstablishedSession(with: peerID) {
-            SecureLogger.log("Routing READ ack via mesh to \(peerID.prefix(8))… id=\(receipt.originalMessageID.prefix(8))…",
+        // Prefer mesh for reachable peers; BLE will queue if handshake is needed
+        if mesh.isPeerReachable(peerID) {
+            SecureLogger.log("Routing READ ack via mesh (reachable) to \(peerID.prefix(8))… id=\(receipt.originalMessageID.prefix(8))…",
                             category: SecureLogger.session, level: .debug)
             mesh.sendReadReceipt(receipt, to: peerID)
         } else {
@@ -70,7 +70,9 @@ final class MessageRouter {
     }
 
     func sendDeliveryAck(_ messageID: String, to peerID: String) {
-        if mesh.isPeerConnected(peerID) && mesh.getNoiseService().hasEstablishedSession(with: peerID) {
+        if mesh.isPeerReachable(peerID) {
+            SecureLogger.log("Routing DELIVERED ack via mesh (reachable) to \(peerID.prefix(8))… id=\(messageID.prefix(8))…",
+                            category: SecureLogger.session, level: .debug)
             mesh.sendDeliveryAck(for: messageID, to: peerID)
         } else {
             nostr.sendDeliveryAck(for: messageID, to: peerID)
@@ -101,7 +103,7 @@ final class MessageRouter {
                         category: SecureLogger.session, level: .debug)
         // Prefer mesh if connected; else try Nostr if mapping exists
         for (content, nickname, messageID) in queued {
-            if mesh.isPeerConnected(peerID) {
+            if mesh.isPeerReachable(peerID) {
                 SecureLogger.log("Outbox -> mesh for \(peerID.prefix(8))… id=\(messageID.prefix(8))…",
                                 category: SecureLogger.session, level: .debug)
                 mesh.sendPrivateMessage(content, to: peerID, recipientNickname: nickname, messageID: messageID)