fix: implement LSP server restart mechanism for Justfile changes (#4)

- Add automatic LSP client restart when Justfile is modified/created/deleted
- Enhance error handling with user notifications and restart after 3+ errors
- Add diagnostic monitoring to ensure problems appear in VS Code Problems panel
- Fix issue where syntax errors persist after Justfile fixes

Closes #3

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-authored-by: Claude <[email protected]>

Author: elasticdotventures

src/client.ts

@@ -85,10 +85,18 @@ export async function createLanguageClient(context: vscode.ExtensionContext): Pr
         errorHandler: {
             error: (error, message, count) => {
                 console.error(`[justlang-lsp] LSP Error (${count}):`, error, message);
+                vscode.window.showErrorMessage(`Just LSP Error: ${error?.message || error}`);
+                
+                // After 3 errors, try to restart
+                if (count !== undefined && count >= 3) {
+                    console.warn('[justlang-lsp] Too many errors, attempting restart');
+                    return { action: ErrorAction.Shutdown };
+                }
                 return { action: ErrorAction.Continue };
             },
             closed: () => {
-                console.warn('[justlang-lsp] LSP connection closed');
+                console.warn('[justlang-lsp] LSP connection closed unexpectedly');
+                vscode.window.showWarningMessage('Just Language Server connection closed, attempting restart...');
                 return { action: CloseAction.Restart };
             }
         }
@@ -122,6 +130,15 @@ export async function createLanguageClient(context: vscode.ExtensionContext): Pr
             console.log(`[justlang-lsp] Server message: ${params.message}`);
         });
 
+        // Monitor diagnostics to ensure they're being published
+        client.onNotification('textDocument/publishDiagnostics', (params) => {
+            console.log(`[justlang-lsp] Publishing diagnostics for ${params.uri}: ${params.diagnostics.length} issues`);
+            if (params.diagnostics.length > 0) {
+                // Show Problems panel when diagnostics are published
+                vscode.commands.executeCommand('workbench.action.problems.focus');
+            }
+        });
+
         // Handle server-to-client commands
         client.onRequest('workspace/executeCommand', async (params) => {
             console.log(`[justlang-lsp] Execute command request: ${params.command}`, params.arguments);

src/extension.ts

@@ -95,6 +95,23 @@ export function activate(context: vscode.ExtensionContext) {
 
     if (enableLsp) {
         startLsp();
+        
+        // Watch for Justfile changes and restart LSP if needed
+        const justfileWatcher = vscode.workspace.createFileSystemWatcher('**/*.{just,justfile,Justfile}');
+        
+        const restartLspOnFileChange = async () => {
+            if (client) {
+                logger.info('Justfile changed, restarting LSP client', 'Extension');
+                await stopLsp();
+                await startLsp();
+            }
+        };
+        
+        justfileWatcher.onDidChange(restartLspOnFileChange);
+        justfileWatcher.onDidCreate(restartLspOnFileChange);
+        justfileWatcher.onDidDelete(restartLspOnFileChange);
+        
+        context.subscriptions.push(justfileWatcher);
     } else {
         logger.info('LSP subsystem disabled by configuration', 'Extension');
     }