diff --git a/client/css/styles.css b/client/css/styles.css
index 9592052..968d37f 100644
--- a/client/css/styles.css
+++ b/client/css/styles.css
@@ -140,3 +140,14 @@ textarea {
 
 #connectionStatus.connected    { background: #d4edda; border-color: #28a745; color: #155724; }
 #connectionStatus.disconnected { background: #f8d7da; border-color: #dc3545; color: #721c24; }
+
+/* ---- Connection test status ------------------------------- */
+#connectionTestStatus {
+    font-size: 13px;
+    padding: 4px 8px;
+    border-radius: 4px;
+}
+
+#connectionTestStatus.connection-testing { color: #856404; background: #fff3cd; }
+#connectionTestStatus.connection-success { color: #155724; background: #d4edda; }
+#connectionTestStatus.connection-error   { color: #721c24; background: #f8d7da; }
diff --git a/client/index.html b/client/index.html
index b60951d..df52399 100644
--- a/client/index.html
+++ b/client/index.html
@@ -90,13 +90,15 @@ <h2>Prompts and outputs</h2>
     <div id="output"></div>
 
     <hr>
-    <div style="margin:6px 0; display:flex; flex-wrap:wrap; gap:8px;">
+    <div style="margin:6px 0; display:flex; flex-wrap:wrap; gap:8px; align-items:center;">
         <label>LM Studio URL:
             <input id="baseUrlInput" type="text" size="40" placeholder="localhost:1234/v1">
         </label>
         <label>Model:
             <input id="modelInput" type="text" size="40" placeholder="qwen/qwen2.5-coder-3b-instruct">
         </label>
+        <button id="btnTestConnection" title="Test connection to LM Studio" aria-label="Test connection to LM Studio">Test Connection</button>
+        <span id="connectionTestStatus" aria-live="polite"></span>
     </div>
 
     <!-- Cytoscape.js (graph library) -->
diff --git a/client/js/app.js b/client/js/app.js
index 57e46d9..1a4907e 100644
--- a/client/js/app.js
+++ b/client/js/app.js
@@ -106,6 +106,17 @@ document.getElementById('btnImportJson').addEventListener('click', function () {
     vscode.postMessage({ command: 'importJSON' });
 });
 
+document.getElementById('btnTestConnection').addEventListener('click', function () {
+    const baseUrl = document.getElementById('baseUrlInput').value || '';
+    const model = document.getElementById('modelInput').value || '';
+    const statusEl = document.getElementById('connectionTestStatus');
+    if (statusEl) {
+        statusEl.textContent = 'Testing...';
+        statusEl.className = 'connection-testing';
+    }
+    vscode.postMessage({ command: 'testConnection', baseUrl: baseUrl, model: model });
+});
+
 /* =============================================================
    3.  General helpers
    ============================================================= */
@@ -264,6 +275,14 @@ window.addEventListener('message', function (event) {
         if (modelInput && message.LLMmodel) { modelInput.value = message.LLMmodel; }
     }
 
+    if (message.command === 'connectionTestResult') {
+        const statusEl = document.getElementById('connectionTestStatus');
+        if (statusEl) {
+            statusEl.textContent = message.message;
+            statusEl.className = message.success ? 'connection-success' : 'connection-error';
+        }
+    }
+
     if (message.command === 'leafSimilarities') {
         renderSimilarities(message.node, message.similarities);
         renderLizardMetrics(message.node);
diff --git a/media/webview.html b/media/webview.html
index a0b42b5..ddde021 100644
--- a/media/webview.html
+++ b/media/webview.html
@@ -143,6 +143,17 @@
         .swatch.other {
             background: var(--color-other);
         }
+
+        /* Connection test status */
+        #connectionTestStatus {
+            font-size: 13px;
+            padding: 4px 8px;
+            border-radius: 4px;
+        }
+
+        #connectionTestStatus.connection-testing { color: #856404; background: #fff3cd; }
+        #connectionTestStatus.connection-success { color: #155724; background: #d4edda; }
+        #connectionTestStatus.connection-error   { color: #721c24; background: #f8d7da; }
     </style>
 
 </head>
@@ -218,13 +229,15 @@ <h2>Code metrics</h2>
     <h2>Prompts and outputs</h2>
     <div id="output"></div>
     <hr>
-    <div style="margin:6px 0; display:flex; flex-wrap:wrap; gap:8px;">
+    <div style="margin:6px 0; display:flex; flex-wrap:wrap; gap:8px; align-items:center;">
         <label>LM_Studio URL:
             <input id="baseUrlInput" type="text" size="40" placeholder="http://localhost:1234/v1" />
         </label>
         <label>Model:
             <input id="modelInput" type="text" size="40" placeholder="qwen/qwen2.5-coder-3b-instruct" />
         </label>
+        <button id="btnTestConnection" title="Test connection to LM Studio" aria-label="Test connection to LM Studio">Test Connection</button>
+        <span id="connectionTestStatus" aria-live="polite"></span>
     </div>
 
     <script>
@@ -313,6 +326,17 @@ <h2>Prompts and outputs</h2>
             vscode.postMessage({ command: 'importJSON' });
         });
 
+        document.getElementById('btnTestConnection').addEventListener('click', () => {
+            const baseUrl = document.getElementById('baseUrlInput').value || '';
+            const model = document.getElementById('modelInput').value || '';
+            const statusEl = document.getElementById('connectionTestStatus');
+            if (statusEl) {
+                statusEl.textContent = 'Testing...';
+                statusEl.className = 'connection-testing';
+            }
+            vscode.postMessage({ command: 'testConnection', baseUrl, model });
+        });
+
         function sendPrompt() {
             const prompt = document.getElementById('prompt').value;
             const code = document.getElementById('code').value;
@@ -445,6 +469,14 @@ <h2>Prompts and outputs</h2>
                 if (modelInput && message.LLMmodel) modelInput.value = message.LLMmodel;
             }
 
+            if (message.command === 'connectionTestResult') {
+                const statusEl = document.getElementById('connectionTestStatus');
+                if (statusEl) {
+                    statusEl.textContent = message.message;
+                    statusEl.className = message.success ? 'connection-success' : 'connection-error';
+                }
+            }
+
             if (message.command === 'leafSimilarities') {
                 // message.node: comlete node selected
                 // message.similarities: [{ id, similarity }, ...]
diff --git a/src/extension.ts b/src/extension.ts
index a83b00a..0c53a48 100644
--- a/src/extension.ts
+++ b/src/extension.ts
@@ -552,6 +552,49 @@ export function activate(context: vscode.ExtensionContext) {
           return;
         }
 
+        if (message.command === 'testConnection') {
+          const testUrl = message.baseUrl || baseUrl;
+          const testModel = message.model || LLMmodel;
+          bonsaiLog('Testing connection to:', testUrl, 'with model:', testModel);
+          panel.webview.postMessage({ command: 'loading', text: 'Testing connection...' });
+
+          try {
+            // Validate URL format (should be host:port/path pattern)
+            if (!/^[\w.-]+(:\d+)?(\/[\w./]*)?$/.test(testUrl)) {
+              throw new Error('Invalid URL format. Expected format: host:port/path (e.g., localhost:1234/v1)');
+            }
+
+            const res = await fetch(`http://${testUrl}/chat/completions`, {
+              method: 'POST',
+              headers: {
+                'Content-Type': 'application/json',
+                'Authorization': 'Bearer lm-studio',
+              },
+              body: JSON.stringify({
+                model: testModel,
+                messages: [{ role: 'user', content: 'Say "connected" in one word.' }],
+                temperature: 0,
+                max_tokens: 10,
+                stream: false,
+              }),
+            });
+
+            if (!res.ok) {
+              const text = await res.text().catch(() => '');
+              throw new Error(`HTTP ${res.status} ${res.statusText}${text ? ` - ${text}` : ''}`);
+            }
+
+            const json: any = await res.json();
+            const output = json?.choices?.[0]?.message?.content?.trim?.() ?? '';
+            bonsaiLog('Connection test successful. Response:', output);
+            panel.webview.postMessage({ command: 'connectionTestResult', success: true, message: `✓ Connected! Model responded: "${output}"` });
+          } catch (err: any) {
+            bonsaiLog('Connection test failed:', err?.message || err);
+            panel.webview.postMessage({ command: 'connectionTestResult', success: false, message: `✗ Connection failed: ${err?.message || err}` });
+          }
+          return;
+        }
+
         if (message.command === 'generate') {
           const selectedNodeIdForPrompt = selectedNodeId;
           let code = message.code;
diff --git a/src/server.ts b/src/server.ts
index d16d78a..415bcbb 100644
--- a/src/server.ts
+++ b/src/server.ts
@@ -489,6 +489,49 @@ async function handleMessage(message: any): Promise<void> {
     bonsaiLog('Config updated – baseUrl:', baseUrl, 'model:', LLMmodel);
     return;
   }
+
+  if (message.command === 'testConnection') {
+    const testUrl = message.baseUrl || baseUrl;
+    const testModel = message.model || LLMmodel;
+    bonsaiLog('Testing connection to:', testUrl, 'with model:', testModel);
+    broadcast({ command: 'loading', text: 'Testing connection...' });
+
+    try {
+      // Validate URL format (should be host:port/path pattern)
+      if (!/^[\w.-]+(:\d+)?(\/[\w./]*)?$/.test(testUrl)) {
+        throw new Error('Invalid URL format. Expected format: host:port/path (e.g., localhost:1234/v1)');
+      }
+
+      const res = await fetch(`http://${testUrl}/chat/completions`, {
+        method: 'POST',
+        headers: {
+          'Content-Type': 'application/json',
+          'Authorization': 'Bearer lm-studio',
+        },
+        body: JSON.stringify({
+          model: testModel,
+          messages: [{ role: 'user', content: 'Say "connected" in one word.' }],
+          temperature: 0,
+          max_tokens: 10,
+          stream: false,
+        }),
+      });
+
+      if (!res.ok) {
+        const text = await res.text().catch(() => '');
+        throw new Error(`HTTP ${res.status} ${res.statusText}${text ? ` - ${text}` : ''}`);
+      }
+
+      const json: any = await res.json();
+      const output = json?.choices?.[0]?.message?.content?.trim?.() ?? '';
+      bonsaiLog('Connection test successful. Response:', output);
+      broadcast({ command: 'connectionTestResult', success: true, message: `✓ Connected! Model responded: "${output}"` });
+    } catch (err: any) {
+      bonsaiLog('Connection test failed:', err?.message || err);
+      broadcast({ command: 'connectionTestResult', success: false, message: `✗ Connection failed: ${err?.message || err}` });
+    }
+    return;
+  }
 }
 
 // ---------------------------------------------------------------------------