feat(lsp): add background daemon for language servers

src/client.ts

@@ -60,6 +60,10 @@ export class LspClient {
   // can await readiness.
   private progressTokens = new Set<string | number>();
   private progressListeners = new Set<() => void>();
+  // Per-URI Version Counter - LSP requires monotonically increasing
+  // version numbers in didOpen/didChange. We track them so the daemon
+  // can resync files via notifyChange after on-disk edits.
+  private versions = new Map<string, number>();
 
   constructor(private readonly server: ServerConfig) {}
 
@@ -182,9 +186,12 @@ export class LspClient {
 
   // Open Document - Reads the file from disk and sends didOpen. Most
   // servers require this before they'll answer hover/definition/etc.
+  // Idempotent-ish: callers should track whether they've already opened
+  // a URI and prefer notifyChange for subsequent syncs.
   openDocument(filePath: string): string {
     const uri = pathToUri(filePath);
     const text = fs.readFileSync(filePath, "utf8");
+    this.versions.set(uri, 1);
     this.conn.sendNotification("textDocument/didOpen", {
       textDocument: {
         uri,
@@ -196,11 +203,32 @@ export class LspClient {
     return uri;
   }
 
+  // Notify Change - Re-reads the file from disk and sends a full-text
+  // didChange. Used by the daemon to keep the server in sync after the
+  // agent's edit/write tools modify a file.
+  notifyChange(filePath: string): string {
+    const uri = pathToUri(filePath);
+    const text = fs.readFileSync(filePath, "utf8");
+    const version = (this.versions.get(uri) ?? 1) + 1;
+    this.versions.set(uri, version);
+    this.conn.sendNotification("textDocument/didChange", {
+      textDocument: { uri, version },
+      contentChanges: [{ text }],
+    });
+    return uri;
+  }
+
   // Send Raw LSP Request - Passthrough used by the command dispatcher.
   sendRequest<R = unknown>(method: string, params: unknown): Promise<R> {
     return this.conn.sendRequest(method, params) as Promise<R>;
   }
 
+  // Clear Diagnostics - Drops the cached diagnostics for a URI so callers
+  // can force waitForDiagnostics to await a fresh publish after didChange.
+  clearDiagnostics(uri: string): void {
+    this.diagnostics.delete(uri);
+  }
+
   // Wait For Diagnostics - Resolves on the first publish for `uri` or
   // after `timeoutMs`. Returns whatever we have for that URI.
   async waitForDiagnostics(