diff --git a/package-lock.json b/package-lock.json
index 08ce22f..694d8ec 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -1,12 +1,12 @@
 {
   "name": "source-doc",
-  "version": "0.2.1",
+  "version": "0.3.0",
   "lockfileVersion": 3,
   "requires": true,
   "packages": {
     "": {
       "name": "source-doc",
-      "version": "0.2.1",
+      "version": "0.3.0",
       "license": "MIT",
       "devDependencies": {
         "@types/glob": "^8.1.0",
diff --git a/src/explanationProvider.ts b/src/explanationProvider.ts
index f089275..8b8e142 100644
--- a/src/explanationProvider.ts
+++ b/src/explanationProvider.ts
@@ -78,13 +78,13 @@ export class ExplanationProvider implements vscode.Disposable {
             if (err instanceof vscode.LanguageModelError) {
                 switch (err.code) {
                     case 'NoPermissions':
-                        throw new Error('Copilot access denied. Please check your GitHub Copilot subscription.');
+                        throw new Error(`Copilot error (${err.code}): access denied. Please check your GitHub Copilot subscription.`);
                     case 'Blocked':
-                        throw new Error('Copilot request was blocked. Please check your GitHub Copilot settings.');
+                        throw new Error(`Copilot error (${err.code}): request was blocked. Please check your GitHub Copilot settings.`);
                     case 'NotFound':
-                        throw new Error('Copilot model not found. Please check your GitHub Copilot extension.');
+                        throw new Error(`Copilot error (${err.code}): model not found. Please check your GitHub Copilot extension.`);
                     case 'RequestFailed':
-                        throw new Error('Copilot request failed. Please try again.');
+                        throw new Error(`Copilot error (${err.code}): request failed. Please try again.`);
                     default:
                         throw new Error(`Copilot error (${err.code}): ${err.message}. Please check your GitHub Copilot extension.`);
                 }
@@ -93,6 +93,9 @@ export class ExplanationProvider implements vscode.Disposable {
         }
 
         result = result.trim();
+        if (token.isCancellationRequested) {
+            throw new vscode.CancellationError();
+        }
         if (!result) {
             throw new Error('Copilot returned an empty explanation. Please try again.');
         }
diff --git a/src/extension.ts b/src/extension.ts
index ae5141d..0b42d67 100644
--- a/src/extension.ts
+++ b/src/extension.ts
@@ -30,7 +30,13 @@ export function activate(context: vscode.ExtensionContext): void {
     );
 
     // ── Register CodeLens provider for each configured language ──────────────
-    registerCodeLensProviders(context, codeLensProvider);
+    // Track ALL registrations in languageRegistrations (not context.subscriptions)
+    // so the full set can be disposed when sourceDoc.languages changes.
+    let languageRegistrations: vscode.Disposable[] = [];
+    registerCodeLensProviders(codeLensProvider, languageRegistrations);
+
+    // Dispose the language registrations when the extension is deactivated.
+    context.subscriptions.push({ dispose: () => languageRegistrations.forEach(d => d.dispose()) });
 
     // Refresh lenses when the user switches to a different editor tab
     context.subscriptions.push(
@@ -43,14 +49,12 @@ export function activate(context: vscode.ExtensionContext): void {
     );
 
     // Re-register providers when sourceDoc.languages changes
-    let languageRegistrations: vscode.Disposable[] = [];
     context.subscriptions.push(
         vscode.workspace.onDidChangeConfiguration(e => {
             if (e.affectsConfiguration('sourceDoc.languages')) {
                 languageRegistrations.forEach(d => d.dispose());
                 languageRegistrations = [];
-                registerCodeLensProviders(context, codeLensProvider, languageRegistrations);
-                languageRegistrations.forEach(d => context.subscriptions.push(d));
+                registerCodeLensProviders(codeLensProvider, languageRegistrations);
             }
         }),
     );
@@ -206,9 +210,8 @@ export function deactivate(): void {
 // ── Helpers ───────────────────────────────────────────────────────────────────
 
 function registerCodeLensProviders(
-    context: vscode.ExtensionContext,
     provider: SourceDocCodeLensProvider,
-    into: vscode.Disposable[] = context.subscriptions as unknown as vscode.Disposable[],
+    into: vscode.Disposable[],
 ): void {
     const config = vscode.workspace.getConfiguration('sourceDoc');
     const languages = config.get<string[]>('languages') ?? [