feat: enhance VSCode API compatibility with fallback state management

webview/src/helpers/codeBlocks.ts

@@ -707,6 +707,8 @@ export function addTopLinePillLabel(builder: any[], lineEnd: number, labelText:
 }
 
 const quotedFenceOpeningLineRegex = /^[ \t]{0,3}(?:>[ \t]?)*[ \t]{0,3}(?:`{3,}|~{3,})/;
+const fenceLineRegex = /^[ \t]*[`~]{3,}.*$/;
+const quotedFencePrefixRegex = /^[ \t]{0,3}((?:>[ \t]?)*)[ \t]{0,3}(?:`{3,}|~{3,})/;
 
 export function addFenceOpeningLineMarker(builder: any[], state: EditorState, from: number, activeLines: Set<number>, addRange: Function, activeLineMarkerDeco: any, fenceMarkerDeco: any): void {
   const line = state.doc.lineAt(from);
@@ -797,15 +799,15 @@ export function addMermaidDiagramBlock(
 export function addCopyCodeButton(builder: any[], state: EditorState, from: number, to: number): void {
   const startLine = state.doc.lineAt(from);
   const endLine = state.doc.lineAt(Math.max(to - 1, from));
+  const quoteDepth = getQuotedFenceDepth(startLine.text);
 
   const codeLines: string[] = [];
   for (let lineNum = startLine.number + 1; lineNum <= endLine.number; lineNum += 1) {
     const line = state.doc.line(lineNum);
-    const lineText = line.text;
+    const lineText = stripLeadingQuotePrefix(line.text, quoteDepth);
 
     if (lineNum === endLine.number) {
-      const fenceMatch = /^[ \t]*[`~]{3,}.*$/.exec(lineText);
-      if (fenceMatch) {
+      if (fenceLineRegex.test(lineText)) {
         continue;
       }
     }
@@ -820,3 +822,24 @@ export function addCopyCodeButton(builder: any[], state: EditorState, from: numb
 
   addTopLineCopyButton(builder, startLine.to, codeContent);
 }
+
+function getQuotedFenceDepth(lineText: string): number {
+  const match = quotedFencePrefixRegex.exec(lineText);
+  if (!match) {
+    return 0;
+  }
+  return (match[1].match(/>/g) ?? []).length;
+}
+
+function stripLeadingQuotePrefix(lineText: string, quoteDepth: number): string {
+  if (quoteDepth <= 0) {
+    return lineText;
+  }
+
+  const prefixRe = new RegExp(`^[ \\t]{0,3}(?:>[ \\t]?){${quoteDepth}}`);
+  const match = prefixRe.exec(lineText);
+  if (!match) {
+    return lineText;
+  }
+  return lineText.slice(match[0].length);
+}

webview/src/index.ts

@@ -14,7 +14,53 @@ import { createExportHandler, type ExportHandlerContext } from './helpers/export
 
 type CreateEditorFactory = (typeof import('./editor'))['createEditor'];
 
-const vscode = acquireVsCodeApi();
+type CompatibleVsCodeWebviewApi = {
+  postMessage: (message: WebviewMessage) => void;
+  getState: () => unknown;
+  setState: (state: unknown) => void;
+};
+
+function createCompatibleVsCodeApi(): CompatibleVsCodeWebviewApi {
+  const hostApi = acquireVsCodeApi();
+  let fallbackState: unknown;
+
+  const getState = (): unknown => {
+    if (typeof hostApi.getState !== 'function') {
+      return fallbackState;
+    }
+
+    try {
+      const hostState = hostApi.getState();
+      if (hostState !== undefined) {
+        fallbackState = hostState;
+      }
+      return hostState;
+    } catch {
+      return fallbackState;
+    }
+  };
+
+  const setState = (state: unknown): void => {
+    fallbackState = state;
+    if (typeof hostApi.setState !== 'function') {
+      return;
+    }
+
+    try {
+      hostApi.setState(state);
+    } catch {
+      // Keep session-local fallback state when host persistence is unavailable.
+    }
+  };
+
+  return {
+    postMessage: (message: WebviewMessage) => hostApi.postMessage(message),
+    getState,
+    setState
+  };
+}
+
+const vscode = createCompatibleVsCodeApi();
 initializeImageHandling(vscode);
 initializeWikiLinkHandling(vscode);
 initializeLocalLinkHandling(vscode);

webview/src/types.d.ts

@@ -1,8 +1,8 @@
 declare function acquireVsCodeApi(): VsCodeWebviewApi;
 
 interface VsCodeWebviewApi {
-  getState(): unknown;
-  setState(state: unknown): void;
+  getState?(): unknown;
+  setState?(state: unknown): void;
   postMessage(message: WebviewMessage): void;
 }