From d8b69a9f8e4f84b38cc43fc371e0f87ac8fac4d1 Mon Sep 17 00:00:00 2001
From: n0dasalt <n0dasalt@gmail.com>
Date: Sat, 31 Jan 2026 16:17:04 +0900
Subject: [PATCH] Fix: Prevent 'Webview is disposed' error on reopening preview
 - Filter disposed panels in getPanel() - Remove disposed panels from
 webviewPanels array - Fixes #8

---
 src/MarkwhenTimelineEditorProvider.ts | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/src/MarkwhenTimelineEditorProvider.ts b/src/MarkwhenTimelineEditorProvider.ts
index f173ebb..5250816 100644
--- a/src/MarkwhenTimelineEditorProvider.ts
+++ b/src/MarkwhenTimelineEditorProvider.ts
@@ -16,7 +16,15 @@ import { DisplayScale } from "./utilities/dateTimeUtilities";
 
 export let webviewPanels = [] as vscode.WebviewPanel[];
 const getPanel = () => {
-  return webviewPanels[webviewPanels.length - 1];
+  const validPanels = webviewPanels.filter(panel => {
+    try {
+      panel.webview.postMessage({});
+      return true;
+    } catch {
+      return false;
+    }
+  });
+  return validPanels[validPanels.length - 1];
 };
 
 export class MarkwhenTimelineEditorProvider
@@ -252,8 +260,9 @@ export class MarkwhenTimelineEditorProvider
       }
     };
 
-    getPanel().onDidDispose(() => {
+    webviewPanel.onDidDispose(() => {
       changeDocumentSubscription.dispose();
+      webviewPanels = webviewPanels.filter(panel => panel !== webviewPanel);
     });
 
     this.updateWebview();