diff --git a/global.json b/global.json
index 67d23d48..c3152d8c 100644
--- a/global.json
+++ b/global.json
@@ -3,7 +3,7 @@
     "Uno.Sdk": "6.5.31"
   },
   "sdk": {
-    "version": "10.0.202",
+    "version": "10.0.103",
     "rollForward": "latestPatch",
     "allowPrerelease": false
   }
diff --git a/src/SalmonEgg.Presentation.Core/Services/Chat/AcpConnectionSessionRegistry.cs b/src/SalmonEgg.Presentation.Core/Services/Chat/AcpConnectionSessionRegistry.cs
index a1d27587..38791a06 100644
--- a/src/SalmonEgg.Presentation.Core/Services/Chat/AcpConnectionSessionRegistry.cs
+++ b/src/SalmonEgg.Presentation.Core/Services/Chat/AcpConnectionSessionRegistry.cs
@@ -53,6 +53,7 @@ public sealed class InMemoryAcpConnectionSessionRegistry : IAcpConnectionSession
 {
     private readonly object _gate = new();
     private readonly Dictionary<string, AcpConnectionSession> _sessionsByProfile = new(StringComparer.Ordinal);
+    private readonly Dictionary<IChatService, string> _profileIdByService = new();
 
     /// <inheritdoc />
     public event Action<string, bool>? ProfileConnectionChanged;
@@ -70,13 +71,10 @@ public bool TryGetProfileId(IChatService service, out string profileId)
         ArgumentNullException.ThrowIfNull(service);
         lock (_gate)
         {
-            foreach (var pair in _sessionsByProfile)
+            if (_profileIdByService.TryGetValue(service, out var foundProfileId))
             {
-                if (ReferenceEquals(pair.Value.Service, service))
-                {
-                    profileId = pair.Key;
-                    return true;
-                }
+                profileId = foundProfileId;
+                return true;
             }
         }
 
@@ -89,10 +87,16 @@ public void Upsert(AcpConnectionSession session)
         ArgumentNullException.ThrowIfNull(session);
         lock (_gate)
         {
+            if (_sessionsByProfile.TryGetValue(session.ProfileId, out var existingSession) && !ReferenceEquals(existingSession.Service, session.Service))
+            {
+                _profileIdByService.Remove(existingSession.Service);
+            }
+
             _sessionsByProfile[session.ProfileId] = session with
             {
                 LastUsedUtc = session.LastUsedUtc == default ? DateTime.UtcNow : session.LastUsedUtc
             };
+            _profileIdByService[session.Service] = session.ProfileId;
         }
 
         // Raise outside the lock to avoid potential deadlocks from re-entrant subscribers.
@@ -104,7 +108,15 @@ public bool RemoveByProfile(string profileId)
         bool removed;
         lock (_gate)
         {
-            removed = _sessionsByProfile.Remove(profileId);
+            if (_sessionsByProfile.TryGetValue(profileId, out var session))
+            {
+                _profileIdByService.Remove(session.Service);
+                removed = _sessionsByProfile.Remove(profileId);
+            }
+            else
+            {
+                removed = false;
+            }
         }
 
         if (removed)
@@ -123,15 +135,12 @@ public bool RemoveByService(IChatService service, out string profileId)
 
         lock (_gate)
         {
-            foreach (var pair in _sessionsByProfile)
+            if (_profileIdByService.TryGetValue(service, out var foundProfileId))
             {
-                if (ReferenceEquals(pair.Value.Service, service))
-                {
-                    profileId = pair.Key;
-                    _sessionsByProfile.Remove(pair.Key);
-                    removed = true;
-                    break;
-                }
+                profileId = foundProfileId;
+                _profileIdByService.Remove(service);
+                _sessionsByProfile.Remove(profileId);
+                removed = true;
             }
         }
 
@@ -164,7 +173,11 @@ public IReadOnlyList<AcpConnectionSession> RemoveWhere(Func<AcpConnectionSession
 
             foreach (var key in keysToRemove)
             {
-                _sessionsByProfile.Remove(key);
+                if (_sessionsByProfile.TryGetValue(key, out var session))
+                {
+                    _profileIdByService.Remove(session.Service);
+                    _sessionsByProfile.Remove(key);
+                }
             }
         }