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/TransportConfig.swift

@@ -62,7 +62,7 @@ enum TransportConfig {
     static let uiRecentCutoffFiveMinutesSeconds: TimeInterval = 5 * 60
 
     // BLE maintenance & thresholds
-    static let bleMaintenanceInterval: TimeInterval = 10.0
+    static let bleMaintenanceInterval: TimeInterval = 5.0
     static let bleMaintenanceLeewaySeconds: Int = 1
     static let bleIsolationRelaxThresholdSeconds: TimeInterval = 60
     static let bleRecentTimeoutWindowSeconds: TimeInterval = 60
@@ -71,23 +71,32 @@ enum TransportConfig {
     static let bleRSSIIsolatedRelaxed: Int = -92
     static let bleRSSIConnectedThreshold: Int = -85
     static let bleRSSIHighTimeoutThreshold: Int = -80
-    static let blePeerInactivityTimeoutSeconds: TimeInterval = 20.0
+    // How long without seeing traffic before we sanity-check the direct link
+    // Lowered to make connected→reachable icon changes react faster when walking out of range
+    static let blePeerInactivityTimeoutSeconds: TimeInterval = 8.0
+    // How long to retain a peer as "reachable" (not directly connected) since lastSeen
+    static let bleReachabilityRetentionVerifiedSeconds: TimeInterval = 21.0    // 21s for verified/favorites
+    static let bleReachabilityRetentionUnverifiedSeconds: TimeInterval = 21.0  // 21s for unknown/unverified
     static let bleFragmentLifetimeSeconds: TimeInterval = 30.0
     static let bleIngressRecordLifetimeSeconds: TimeInterval = 3.0
     static let bleConnectTimeoutBackoffWindowSeconds: TimeInterval = 120.0
     static let bleRecentPacketWindowSeconds: TimeInterval = 30.0
     static let bleRecentPacketWindowMaxCount: Int = 100
+    // Keep scanning fully ON when we saw traffic very recently
+    static let bleRecentTrafficForceScanSeconds: TimeInterval = 10.0
     static let bleThreadSleepWriteShortDelaySeconds: TimeInterval = 0.05
     static let bleExpectedWritePerFragmentMs: Int = 8
     static let bleExpectedWriteMaxMs: Int = 2000
-    static let bleFragmentSpacingMs: Int = 6
-    static let bleAnnounceIntervalSeconds: TimeInterval = 10.0
+    // Faster fragment pacing; use slightly tighter spacing for directed trains
+    static let bleFragmentSpacingMs: Int = 5
+    static let bleFragmentSpacingDirectedMs: Int = 4
+    static let bleAnnounceIntervalSeconds: TimeInterval = 4.0
     static let bleDutyOnDurationDense: TimeInterval = 3.0
     static let bleDutyOffDurationDense: TimeInterval = 15.0
-    static let bleConnectedAnnounceBaseSecondsDense: TimeInterval = 90.0
-    static let bleConnectedAnnounceBaseSecondsSparse: TimeInterval = 45.0
-    static let bleConnectedAnnounceJitterDense: TimeInterval = 20.0
-    static let bleConnectedAnnounceJitterSparse: TimeInterval = 7.5
+    static let bleConnectedAnnounceBaseSecondsDense: TimeInterval = 30.0
+    static let bleConnectedAnnounceBaseSecondsSparse: TimeInterval = 15.0
+    static let bleConnectedAnnounceJitterDense: TimeInterval = 8.0
+    static let bleConnectedAnnounceJitterSparse: TimeInterval = 4.0
 
     // Location
     static let locationDistanceFilterMeters: Double = 1000
@@ -126,12 +135,24 @@ enum TransportConfig {
     static let geoRelayFetchIntervalSeconds: TimeInterval = 60 * 60 * 24
 
     // BLE operational delays
-    static let bleInitialAnnounceDelaySeconds: TimeInterval = 2.0
+    static let bleInitialAnnounceDelaySeconds: TimeInterval = 0.6
     static let bleConnectTimeoutSeconds: TimeInterval = 8.0
     static let bleRestartScanDelaySeconds: TimeInterval = 0.1
-    static let blePostSubscribeAnnounceDelaySeconds: TimeInterval = 0.1
+    static let blePostSubscribeAnnounceDelaySeconds: TimeInterval = 0.05
     static let blePostAnnounceDelaySeconds: TimeInterval = 0.4
-    static let bleForceAnnounceMinIntervalSeconds: TimeInterval = 0.2
+    static let bleForceAnnounceMinIntervalSeconds: TimeInterval = 0.15
+
+    // Store-and-forward for directed packets at relays
+    static let bleDirectedSpoolWindowSeconds: TimeInterval = 15.0
+
+    // Log/UI debounce windows
+    // Shorter debounce so UI reacts faster while still suppressing duplicate callbacks
+    static let bleDisconnectNotifyDebounceSeconds: TimeInterval = 0.9
+    static let bleReconnectLogDebounceSeconds: TimeInterval = 2.0
+
+    // Weak-link cooldown after connection timeouts
+    static let bleWeakLinkCooldownSeconds: TimeInterval = 30.0
+    static let bleWeakLinkRSSICutoff: Int = -90
 
     // Content hashing / formatting
     static let contentKeyPrefixLength: Int = 256