diff --git a/MosswartMassacre/ViewXML/mainViewTabbed.xml b/MosswartMassacre/ViewXML/mainViewTabbed.xml
index c958f39..6ed6230 100644
--- a/MosswartMassacre/ViewXML/mainViewTabbed.xml
+++ b/MosswartMassacre/ViewXML/mainViewTabbed.xml
@@ -42,6 +42,9 @@
         <control progid="DecalControls.Checkbox" name="chkVitalSharingEnabled" left="20" top="110" width="200" height="20" text="Vital Sharing (cross-PC)" checked="false"/>
         <control progid="DecalControls.PushButton" name="btnVitalSharingOverlay" left="220" top="108" width="100" height="22" text="Open Overlay"/>
 
+        <!-- Verbose logging -->
+        <control progid="DecalControls.Checkbox" name="chkVerboseLogging" left="20" top="230" width="300" height="20" text="Verbose logging (vital sharing / VTank feed)" checked="false"/>
+
         <!-- Character tag setting -->
         <control progid="DecalControls.StaticText" name="lblCharTag" left="20" top="140" width="100" height="16" text="Character Tag:"/>
         <control progid="DecalControls.Edit" name="txtCharTag" left="125" top="138" width="150" height="20" text="default"/>
diff --git a/MosswartMassacre/Views/VVSTabbedMainView.cs b/MosswartMassacre/Views/VVSTabbedMainView.cs
index fe9573b..c30b35f 100644
--- a/MosswartMassacre/Views/VVSTabbedMainView.cs
+++ b/MosswartMassacre/Views/VVSTabbedMainView.cs
@@ -34,6 +34,7 @@ namespace MosswartMassacre.Views
         private HudCheckBox chkAutoUpdateEnabled;
         private HudCheckBox chkVitalSharingEnabled;
         private HudButton btnVitalSharingOverlay;
+        private HudCheckBox chkVerboseLogging;
         private HudTextBox txtCharTag;
         private HudTextBox txtVTankPath;
         #endregion
@@ -233,6 +234,7 @@ namespace MosswartMassacre.Views
                 chkAutoUpdateEnabled = GetControl<HudCheckBox>("chkAutoUpdateEnabled");
                 chkVitalSharingEnabled = GetControl<HudCheckBox>("chkVitalSharingEnabled");
                 btnVitalSharingOverlay = GetControl<HudButton>("btnVitalSharingOverlay");
+                chkVerboseLogging = GetControl<HudCheckBox>("chkVerboseLogging");
                 txtCharTag = GetControl<HudTextBox>("txtCharTag");
                 txtVTankPath = GetControl<HudTextBox>("txtVTankPath");
 
@@ -247,6 +249,8 @@ namespace MosswartMassacre.Views
                     chkVitalSharingEnabled.Change += OnVitalSharingSettingChanged;
                 if (btnVitalSharingOverlay != null)
                     btnVitalSharingOverlay.Hit += OnVitalSharingOverlayClicked;
+                if (chkVerboseLogging != null)
+                    chkVerboseLogging.Change += OnVerboseLoggingSettingChanged;
                 if (txtCharTag != null)
                     txtCharTag.Change += OnCharTagChanged;
                 if (txtVTankPath != null)
@@ -496,6 +500,19 @@ namespace MosswartMassacre.Views
             }
         }
 
+        private void OnVerboseLoggingSettingChanged(object sender, EventArgs e)
+        {
+            try
+            {
+                PluginSettings.Instance.VerboseLogging = chkVerboseLogging.Checked;
+                PluginCore.WriteToChat($"Verbose logging {(chkVerboseLogging.Checked ? "ENABLED" : "DISABLED")}.");
+            }
+            catch (Exception ex)
+            {
+                PluginCore.WriteToChat($"Error in verbose logging setting change: {ex.Message}");
+            }
+        }
+
         private void OnVTankPathChanged(object sender, EventArgs e)
         {
             try
@@ -651,6 +668,8 @@ namespace MosswartMassacre.Views
                 {
                     if (chkVitalSharingEnabled != null)
                         chkVitalSharingEnabled.Checked = PluginSettings.Instance.VitalSharingEnabled;
+                    if (chkVerboseLogging != null)
+                        chkVerboseLogging.Checked = PluginSettings.Instance.VerboseLogging;
                     if (chkRareMetaEnabled != null)
                         chkRareMetaEnabled.Checked = PluginSettings.Instance.RareMetaEnabled;
                     if (chkWebSocketEnabled != null)
diff --git a/MosswartMassacre/VitalSharingTracker.cs b/MosswartMassacre/VitalSharingTracker.cs
index 6a93b6b..d60f87a 100644
--- a/MosswartMassacre/VitalSharingTracker.cs
+++ b/MosswartMassacre/VitalSharingTracker.cs
@@ -259,7 +259,11 @@ namespace MosswartMassacre
             {
                 try
                 {
-                    if (vTank.Instance == null) return;
+                    if (vTank.Instance == null)
+                    {
+                        VerboseLog($"[VitalShare→VTank] SKIP HelperPlayerUpdate ({fromChar}): vTank.Instance is null");
+                        return;
+                    }
                     var info = new sPlayerInfoUpdate
                     {
                         PlayerID = playerId,
@@ -274,6 +278,7 @@ namespace MosswartMassacre
                         maxStam = maxS,
                     };
                     vTank.Instance.HelperPlayerUpdate(info);
+                    VerboseLog($"[VitalShare→VTank] HelperPlayerUpdate {fromChar} (0x{playerId:X8}) HP={curH}/{maxH} S={curS}/{maxS} M={curM}/{maxM}");
                 }
                 catch (Exception ex) { _logger?.Log($"[VitalShare] HelperPlayerUpdate error: {ex.Message}"); }
             });
@@ -320,9 +325,18 @@ namespace MosswartMassacre
             {
                 try
                 {
-                    if (vTank.Instance == null) return;
-                    if (!CoreManager.Current.Actions.IsValidObject(target)) return;
+                    if (vTank.Instance == null)
+                    {
+                        VerboseLog($"[VitalShare→VTank] SKIP LogCastAttempt (from {fromChar}): vTank.Instance is null");
+                        return;
+                    }
+                    if (!CoreManager.Current.Actions.IsValidObject(target))
+                    {
+                        VerboseLog($"[VitalShare→VTank] SKIP LogCastAttempt (from {fromChar}): target 0x{target:X8} not a valid object locally");
+                        return;
+                    }
                     vTank.Instance.LogCastAttempt(spellId, target, (int)skill);
+                    VerboseLog($"[VitalShare→VTank] LogCastAttempt from {fromChar}: spell={spellId} target=0x{target:X8} skill={(int)skill}");
                 }
                 catch (Exception ex) { _logger?.Log($"[VitalShare] LogCastAttempt error: {ex.Message}"); }
             });
@@ -343,9 +357,18 @@ namespace MosswartMassacre
             {
                 try
                 {
-                    if (vTank.Instance == null) return;
-                    if (!CoreManager.Current.Actions.IsValidObject(target)) return;
+                    if (vTank.Instance == null)
+                    {
+                        VerboseLog($"[VitalShare→VTank] SKIP LogSpellCast (from {fromChar}): vTank.Instance is null");
+                        return;
+                    }
+                    if (!CoreManager.Current.Actions.IsValidObject(target))
+                    {
+                        VerboseLog($"[VitalShare→VTank] SKIP LogSpellCast (from {fromChar}): target 0x{target:X8} not a valid object locally");
+                        return;
+                    }
                     vTank.Instance.LogSpellCast(target, spellId, duration);
+                    VerboseLog($"[VitalShare→VTank] LogSpellCast from {fromChar}: spell={spellId} target=0x{target:X8} duration={duration}ms");
                 }
                 catch (Exception ex) { _logger?.Log($"[VitalShare] LogSpellCast error: {ex.Message}"); }
             });
@@ -542,6 +565,7 @@ namespace MosswartMassacre
                     skill = skill,
                 };
                 _ = WebSocket.SendVitalShareAsync(payload);
+                VerboseLog($"[VitalShare] SEND share_cast_attempt spell={spellId} target=0x{target:X8} skill={(int)skill}");
             }
             catch (Exception ex)
             {
@@ -603,6 +627,7 @@ namespace MosswartMassacre
                     duration_ms = durationMs,
                 };
                 _ = WebSocket.SendVitalShareAsync(payload);
+                VerboseLog($"[VitalShare] SEND share_cast_success spell={spellId} target=0x{target:X8} duration={durationMs}ms");
             }
             catch (Exception ex)
             {
@@ -715,6 +740,24 @@ namespace MosswartMassacre
 
         // --- Helpers ---
 
+        /// <summary>
+        /// Logs a message routed to the plugin chat window, but ONLY when
+        /// PluginSettings.VerboseLogging is true. Used to trace every
+        /// VTank feeding event (HelperPlayerUpdate / LogCastAttempt /
+        /// LogSpellCast) so the user can verify cross-PC coordination is
+        /// actually reaching VTank.
+        /// </summary>
+        private void VerboseLog(string message)
+        {
+            try
+            {
+                if (!PluginSettings.IsInitialized) return;
+                if (!PluginSettings.Instance.VerboseLogging) return;
+                PluginCore.WriteToChat(message);
+            }
+            catch { }
+        }
+
         private string SafeCharacterName()
         {
             try { return CoreManager.Current.CharacterFilter.Name ?? ""; }
diff --git a/MosswartMassacre/bin/Release/MosswartMassacre.dll b/MosswartMassacre/bin/Release/MosswartMassacre.dll
index 70d1e1b..aaa74ff 100644
Binary files a/MosswartMassacre/bin/Release/MosswartMassacre.dll and b/MosswartMassacre/bin/Release/MosswartMassacre.dll differ