feat(vscode): add full chat interface to OpenClaude extension (#608)

Add a Claude Code-like chat experience to the VS Code extension with:
- Streaming chat panel (sidebar + editor tab) with markdown rendering
- Tool use visualization with inline diffs (replace/with display)
- Session history browser with JSONL transcript parsing
- Thinking block indicator with elapsed time and token count
- Clickable file paths that open in the editor
- Permission mode setting (acceptEdits default)
- Multi-turn conversation support via NDJSON stream-json protocol
- Status bar with live activity indicators
- Ctrl+Shift+L keybinding to open chat panel

Made-with: Cursor

Co-authored-by: henriquepasquini2 <henriquepasquini2@users.noreply.github.com>

vscode-extension/openclaude-vscode/src/chat/diffController.js

@@ -0,0 +1,90 @@
+/**
+ * diffController — provides a TextDocumentContentProvider for virtual
+ * diff documents and helpers to open VS Code's native diff editor when
+ * tool use involves file edits.
+ */
+
+const vscode = require('vscode');
+
+const SCHEME = 'openclaude-diff';
+let contentStore = new Map();
+
+class DiffContentProvider {
+  constructor() {
+    this._onDidChange = new vscode.EventEmitter();
+    this.onDidChange = this._onDidChange.event;
+  }
+
+  provideTextDocumentContent(uri) {
+    return contentStore.get(uri.toString()) || '';
+  }
+
+  update(uri) {
+    this._onDidChange.fire(uri);
+  }
+
+  dispose() {
+    this._onDidChange.dispose();
+  }
+}
+
+function storeContent(id, content) {
+  const uri = vscode.Uri.parse(`${SCHEME}:/${id}`);
+  contentStore.set(uri.toString(), content);
+  return uri;
+}
+
+function clearContent(id) {
+  const uri = vscode.Uri.parse(`${SCHEME}:/${id}`);
+  contentStore.delete(uri.toString());
+}
+
+function clearAll() {
+  contentStore.clear();
+}
+
+/**
+ * Opens a diff view between original and modified content.
+ * @param {object} opts
+ * @param {string} opts.filePath - Display path (for the title)
+ * @param {string} opts.original - Original file content
+ * @param {string} opts.modified - Modified file content
+ * @param {string} [opts.toolUseId] - Unique ID for this diff
+ */
+async function openDiff({ filePath, original, modified, toolUseId }) {
+  const id = toolUseId || Math.random().toString(36).slice(2, 10);
+  const originalUri = storeContent(`original-${id}`, original || '');
+  const modifiedUri = storeContent(`modified-${id}`, modified || '');
+  const shortName = filePath ? filePath.split(/[\\/]/).pop() : 'file';
+  const title = `${shortName} (OpenClaude Diff)`;
+
+  await vscode.commands.executeCommand('vscode.diff', originalUri, modifiedUri, title);
+}
+
+/**
+ * Opens a diff between a real file on disk and modified content from
+ * a tool use result.
+ * @param {object} opts
+ * @param {string} opts.filePath - Absolute path to the real file
+ * @param {string} opts.modified - Modified content
+ * @param {string} [opts.toolUseId]
+ */
+async function openFileDiff({ filePath, modified, toolUseId }) {
+  const id = toolUseId || Math.random().toString(36).slice(2, 10);
+  const fileUri = vscode.Uri.file(filePath);
+  const modifiedUri = storeContent(`modified-${id}`, modified || '');
+  const shortName = filePath.split(/[\\/]/).pop() || 'file';
+  const title = `${shortName} (OpenClaude Edit)`;
+
+  await vscode.commands.executeCommand('vscode.diff', fileUri, modifiedUri, title);
+}
+
+module.exports = {
+  DiffContentProvider,
+  SCHEME,
+  openDiff,
+  openFileDiff,
+  storeContent,
+  clearContent,
+  clearAll,
+};