feat(lsp): add background daemon for language servers

index.ts

@@ -1,12 +1,12 @@
 // LSP Extension - Registers tools that let the LLM query language servers
 // for hover, definition, references, completions, document symbols, and
-// diagnostics. Each tool spawns a short-lived server, runs one request,
-// and tears it down (same lifecycle as the CLI).
+// diagnostics. Tool calls are forwarded to the long-lived pi-lsp daemon
+// (autospawned on first use) so LSP servers stay warm across calls.
 import type { ExtensionAPI } from "@mariozechner/pi-coding-agent";
 import { Type } from "typebox";
 import * as path from "node:path";
-import { LspClient, uriToPath } from "./src/client.ts";
-import { pickServer, findRoot } from "./src/root.ts";
+import { uriToPath } from "./src/client.ts";
+import { daemonDiagnostics, daemonRequest } from "./src/daemonClient.ts";
 
 // Format Hover - Turn an LSP hover response into readable text.
 function formatHover(result: unknown): string {
@@ -202,47 +202,21 @@ function formatDiagnostics(result: unknown): string {
     .join("\n");
 }
 
-// Run LSP Request - Spawn a server, open the file, run one request, dispose.
-// Mirrors the CLI lifecycle: fresh server per request.
+// Run LSP Request - Forwards to the daemon, which owns the long-lived
+// LspClient cache and handles didOpen/didChange syncing. The daemon
+// injects textDocument.uri from the file path, so we omit it here.
 async function runLsp(
   filePath: string,
   method: string,
   params: Record<string, unknown>,
 ): Promise<unknown> {
-  const server = pickServer(filePath);
-  const rootDir = findRoot(filePath, server.rootMarkers);
-  const client = new LspClient(server);
-
-  try {
-    await client.start(rootDir);
-    const uri = client.openDocument(filePath);
-    await client.waitForReady();
-    // Populate textDocument.uri if the params have a textDocument field
-    if (params.textDocument && typeof params.textDocument === "object") {
-      params.textDocument = { ...params.textDocument, uri };
-    }
-    return client.sendRequest(method, params);
-  } finally {
-    // Fire-and-forget shutdown; don't wait for graceful exit.
-    void client.dispose();
-  }
+  return daemonRequest(filePath, method, params);
 }
 
-// Run LSP Diagnostics - Diagnostics arrive as a notification, so we use
-// the dedicated waitForDiagnostics helper instead of sendRequest.
+// Run LSP Diagnostics - Diagnostics arrive as a notification, so the
+// daemon has a dedicated op that waits for the next publish.
 async function runDiagnostics(filePath: string): Promise<unknown> {
-  const server = pickServer(filePath);
-  const rootDir = findRoot(filePath, server.rootMarkers);
-  const client = new LspClient(server);
-
-  try {
-    await client.start(rootDir);
-    const uri = client.openDocument(filePath);
-    await client.waitForReady();
-    return client.waitForDiagnostics(uri, 1500);
-  } finally {
-    void client.dispose();
-  }
+  return daemonDiagnostics(filePath, 1500);
 }
 
 // Shared Parameters Schema - All position-based tools accept file + optional
@@ -268,7 +242,6 @@ export default function (pi: ExtensionAPI) {
     async execute(_toolCallId, params, _signal, _onUpdate, ctx) {
       const filePath = path.resolve(ctx.cwd, params.file);
       const lspParams = {
-        textDocument: {},
         position: { line: params.line ?? 0, character: params.character ?? 0 },
       };
       const result = await runLsp(filePath, "textDocument/hover", lspParams);
@@ -289,7 +262,6 @@ export default function (pi: ExtensionAPI) {
     async execute(_toolCallId, params, _signal, _onUpdate, ctx) {
       const filePath = path.resolve(ctx.cwd, params.file);
       const lspParams = {
-        textDocument: {},
         position: { line: params.line ?? 0, character: params.character ?? 0 },
       };
       const result = await runLsp(
@@ -314,7 +286,6 @@ export default function (pi: ExtensionAPI) {
     async execute(_toolCallId, params, _signal, _onUpdate, ctx) {
       const filePath = path.resolve(ctx.cwd, params.file);
       const lspParams = {
-        textDocument: {},
         position: { line: params.line ?? 0, character: params.character ?? 0 },
         context: { includeDeclaration: true },
       };
@@ -340,7 +311,6 @@ export default function (pi: ExtensionAPI) {
     async execute(_toolCallId, params, _signal, _onUpdate, ctx) {
       const filePath = path.resolve(ctx.cwd, params.file);
       const lspParams = {
-        textDocument: {},
         position: { line: params.line ?? 0, character: params.character ?? 0 },
       };
       const result = await runLsp(
@@ -366,9 +336,11 @@ export default function (pi: ExtensionAPI) {
     }),
     async execute(_toolCallId, params, _signal, _onUpdate, ctx) {
       const filePath = path.resolve(ctx.cwd, params.file);
-      const result = await runLsp(filePath, "textDocument/documentSymbol", {
-        textDocument: {},
-      });
+      const result = await runLsp(
+        filePath,
+        "textDocument/documentSymbol",
+        {},
+      );
       return {
         content: [{ type: "text", text: formatDocumentSymbols(result) }],
         details: { raw: result },