From 7e46002b20dbfe6af261fddcd31eda636c9c62e6 Mon Sep 17 00:00:00 2001
From: Nucleic <andrew@blakeslee.me>
Date: Sat, 18 Jul 2026 22:07:15 -0700
Subject: [PATCH] Merge nucleic/lucid-glass-bison-viwq into dev

---
 .../NucleicRemote/Models/HostConnection.swift  | 16 ++++++++++++----
 .../NucleicRemote/Net/NetworkPathMonitor.swift | 18 +++++++++++++++++-
 2 files changed, 29 insertions(+), 5 deletions(-)

diff --git a/NucleicRemote/NucleicRemote/Models/HostConnection.swift b/NucleicRemote/NucleicRemote/Models/HostConnection.swift
index 9048257..581d2e9 100644
--- a/NucleicRemote/NucleicRemote/Models/HostConnection.swift
+++ b/NucleicRemote/NucleicRemote/Models/HostConnection.swift
@@ -1097,10 +1097,18 @@ final class HostConnection {
             reconnect(to: host)
             return
         }
-        // Live over a fallback transport (tailnet/relay) and a LAN path just reappeared (rejoined the
-        // Mac's Wi-Fi) → the return leg of the switch above. The tunnel survives the interface change
-        // on its own, so nothing else would ever re-plan back down to the direct path — probe LAN and
-        // swap to it if the Mac actually answers here.
+        // Live over a fallback transport (tailnet/relay) and the path just changed. On cellular this
+        // is a tower roam that may have rebound our IP and silently killed the WebSocket — the tunnel
+        // does NOT reliably survive an IP rebind, contrary to the interface-swap case. Don't trust the
+        // stale `.connected`: fast-probe it and re-dial the instant it fails to answer (sub-second),
+        // rather than waiting out the 25s relay ping / 55s keepalive / URLSession's own detection.
+        // `revalidate` also runs `maybeUpgradeToLAN`, so the LAN return leg (rejoined the Mac's Wi-Fi)
+        // is still covered here.
+        if connectivity.isLive, activeTransport != .lan {
+            revalidate()
+            return
+        }
+        // Live over LAN (or a path change with nothing to re-probe) → just try the LAN return leg.
         maybeUpgradeToLAN()
     }
 
diff --git a/NucleicRemote/NucleicRemote/Net/NetworkPathMonitor.swift b/NucleicRemote/NucleicRemote/Net/NetworkPathMonitor.swift
index fef5172..84e7ffb 100644
--- a/NucleicRemote/NucleicRemote/Net/NetworkPathMonitor.swift
+++ b/NucleicRemote/NucleicRemote/Net/NetworkPathMonitor.swift
@@ -26,6 +26,13 @@ final class NetworkPathMonitor: ObservableObject {
     private let queue = DispatchQueue(label: "nucleic.remote.path")
     private var started = false
 
+    /// A coarse fingerprint of the last path, so a *same-class* transition (a cellular tower roam
+    /// that reprovisions the pdp interface, a Wi‑Fi interface swap) fires `onChange` too — not just
+    /// the LAN/satisfied flips. Without this, a roam that keeps the path `satisfied` on `.cellular`
+    /// leaves both booleans unchanged and the proactive re‑plan never fires, so a silently‑rebound
+    /// socket is only caught by the slow reactive keepalive.
+    private var lastSignature = ""
+
     func start() {
         guard !started else { return }
         started = true
@@ -43,9 +50,18 @@ final class NetworkPathMonitor: ObservableObject {
         let lan = path.status == .satisfied
             && (path.usesInterfaceType(.wifi) || path.usesInterfaceType(.wiredEthernet))
         let satisfied = path.status == .satisfied
-        let changed = lan != canUseLAN || satisfied != isSatisfied
+        // Also move on a same‑class transition (cellular tower roam, Wi‑Fi interface swap) so a live
+        // relay/tailnet tunnel gets re‑validated instead of waiting out socket‑death detection. The
+        // interface identity + expensiveness/constrained flags are what `NWPath` surfaces on a
+        // handoff; the IP itself isn't exposed, so this is best‑effort — the follow‑on probe is the
+        // gate, and it's cheap on a still‑healthy link.
+        let signature = "\(path.status)|"
+            + path.availableInterfaces.map { "\($0.name)#\($0.index)" }.joined(separator: ",")
+            + "|\(path.isExpensive)|\(path.isConstrained)"
+        let changed = lan != canUseLAN || satisfied != isSatisfied || signature != lastSignature
         canUseLAN = lan
         isSatisfied = satisfied
+        lastSignature = signature
         if changed { onChange?() }
     }
 }