VS Code: decoration-based matching, Ctrl+K bindings, README overhaul (from dev f84517152b7f)

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

doc/edit/vscode/extension.js

@@ -167,6 +167,11 @@ function activate(context) {
     }
     const python = vscode.workspace.getConfiguration('klammertext').get('pythonPath') || 'python3';
     client = new LspClient(python, [serverPath], log);
+    client.proc.on('error', (err) => {
+        vscode.window.showWarningMessage(
+            'Klammertext: could not start the language server (' + err.message +
+            ') — check the klammertext.pythonPath setting.');
+    });
 
     const diagnostics = vscode.languages.createDiagnosticCollection('klammertext');
     context.subscriptions.push(diagnostics, output);
@@ -271,6 +276,58 @@ function activate(context) {
             },
         }));
 
+    // -- live match/mismatch decorations --
+    // Drawn on every cursor move from the server's klammertext/matchInfo.
+    // Deliberately NOT left to occurrence highlighting: VS Code only asks
+    // documentHighlight providers when the cursor is on a word, so a bare @
+    // close would never light up — and a mismatch could not show in red.
+    const matchDecoration = vscode.window.createTextEditorDecorationType({
+        border: '1px solid',
+        borderColor: new vscode.ThemeColor('editorBracketMatch.border'),
+        backgroundColor: new vscode.ThemeColor('editorBracketMatch.background'),
+    });
+    const mismatchDecoration = vscode.window.createTextEditorDecorationType({
+        border: '1px solid #ff5555',
+        fontWeight: 'bold',
+    });
+    context.subscriptions.push(matchDecoration, mismatchDecoration);
+
+    const updateMatchDecorations = (editor) => {
+        if (!editor || !isKt(editor.document)) return;
+        client.request('klammertext/matchInfo',
+            Object.assign(docParams(editor.document),
+                          { position: fromVsPosition(editor.selection.active) }))
+            .then((info) => {
+                if (!info) {
+                    editor.setDecorations(matchDecoration, []);
+                    editor.setDecorations(mismatchDecoration, []);
+                    return;
+                }
+                const ranges = [toVsRange(info.token)];
+                if (info.matchToken) ranges.push(toVsRange(info.matchToken));
+                if (info.mismatch) {
+                    editor.setDecorations(matchDecoration, []);
+                    editor.setDecorations(mismatchDecoration, ranges);
+                    if (info.message) {
+                        vscode.window.setStatusBarMessage(
+                            'Klammertext: ' + info.message, 5000);
+                    }
+                } else {
+                    editor.setDecorations(mismatchDecoration, []);
+                    editor.setDecorations(matchDecoration, ranges);
+                }
+            }, () => { /* server gone: leave decorations as they are */ });
+    };
+    let matchTimer = null;
+    context.subscriptions.push(
+        vscode.window.onDidChangeTextEditorSelection((event) => {
+            if (matchTimer) clearTimeout(matchTimer);
+            matchTimer = setTimeout(
+                () => updateMatchDecorations(event.textEditor), 50);
+        }),
+        vscode.window.onDidChangeActiveTextEditor(
+            (editor) => updateMatchDecorations(editor)));
+
     // -- commands --
     context.subscriptions.push(
         vscode.commands.registerCommand('klammertext.jumpToMatch', () => {