Merge branch 'main' into 0.75.0-branch

# Conflicts:
#	.github/workflows/golang-test-linux.yml
#	client/internal/routemanager/manager.go
#	client/internal/routeselector/routeselector.go
#	client/ui/client_ui.go
#	client/ui/const.go
#	client/ui/event_handler.go

client/internal/routeselector/routeselector.go

@@ -115,6 +115,35 @@ func (rs *RouteSelector) DeselectAllRoutes() {
 	clear(rs.selectedRoutes)
 }
 
+// SetExclusiveExitNode atomically makes preferred the only selected exit node
+// among exitIDs: every other ID in exitIDs is deselected and preferred (when
+// non-empty) is selected, all under a single lock. Holding the lock across the
+// whole reconciliation prevents a concurrent DeselectAllRoutes from interleaving
+// between the deselect and select steps and being silently undone. A global
+// deselect-all is left untouched so the user's "all off" stays in effect;
+// non-exit routes are never referenced, so their selection is preserved.
+func (rs *RouteSelector) SetExclusiveExitNode(preferred route.NetID, exitIDs []route.NetID) {
+	rs.mu.Lock()
+	defer rs.mu.Unlock()
+
+	if rs.deselectAll {
+		return
+	}
+
+	for _, id := range exitIDs {
+		if id == preferred {
+			continue
+		}
+		rs.deselectedRoutes[id] = struct{}{}
+		delete(rs.selectedRoutes, id)
+	}
+
+	if preferred != "" {
+		delete(rs.deselectedRoutes, preferred)
+		rs.selectedRoutes[preferred] = struct{}{}
+	}
+}
+
 // IsDeselectAll reports whether the global "deselect all" flag is set, i.e. the
 // user explicitly disabled every route. Callers enforcing per-route invariants
 // (e.g. single exit node) should leave the selection untouched when it is.