fix(lsp): accepted dynamic capability registration

- Accepted client/registerCapability and client/unregisterCapability server requests so Expert can continue startup before semantic requests.\n- Allowed JSON-RPC string ids on LSP request/response handling.\n- Added a regression test for dynamic registration gating hover.\n\nFixes #3029

packages/coding-agent/CHANGELOG.md

@@ -2,6 +2,10 @@
 
 ## [Unreleased]
 
+### Fixed
+
+- Fixed LSP servers that dynamically register capabilities, including Expert, hanging semantic requests after `client/registerCapability` was rejected ([#3029](https://github.com/can1357/oh-my-pi/issues/3029)).
+
 ## [16.1.0] - 2026-06-19
 
 ### Added

packages/coding-agent/src/lsp/client.ts

@@ -5,6 +5,7 @@ import { applyWorkspaceEdit } from "./edits";
 import { getLspmuxCommand, isLspmuxSupported } from "./lspmux";
 import type {
 	LspClient,
+	LspJsonRpcId,
 	LspJsonRpcNotification,
 	LspJsonRpcRequest,
 	LspJsonRpcResponse,
@@ -416,7 +417,6 @@ function currentWorkspaceFolders(client: LspClient): Array<{ uri: string; name:
  * Handle workspace/workspaceFolders requests from the server.
  */
 async function handleWorkspaceFoldersRequest(client: LspClient, message: LspJsonRpcRequest): Promise<void> {
-	if (typeof message.id !== "number") return;
 	await sendResponse(client, message.id, currentWorkspaceFolders(client), "workspace/workspaceFolders");
 }
 
@@ -424,7 +424,6 @@ async function handleWorkspaceFoldersRequest(client: LspClient, message: LspJson
  * Handle workspace/configuration requests from the server.
  */
 async function handleConfigurationRequest(client: LspClient, message: LspJsonRpcRequest): Promise<void> {
-	if (typeof message.id !== "number") return;
 	const params = message.params as { items?: Array<{ section?: string }> };
 	const items = params?.items ?? [];
 	const result = items.map(item => {
@@ -438,7 +437,6 @@ async function handleConfigurationRequest(client: LspClient, message: LspJsonRpc
  * Handle workspace/applyEdit requests from the server.
  */
 async function handleApplyEditRequest(client: LspClient, message: LspJsonRpcRequest): Promise<void> {
-	if (typeof message.id !== "number") return;
 	const params = message.params as { edit?: WorkspaceEdit };
 	if (!params?.edit) {
 		await sendResponse(
@@ -475,13 +473,15 @@ async function handleServerRequest(client: LspClient, message: LspJsonRpcRequest
 		return;
 	}
 	if (message.method === "window/workDoneProgress/create") {
-		// Accept progress token registration from the server
-		if (typeof message.id === "number") {
-			await sendResponse(client, message.id, null, message.method);
-		}
+		// Accept progress token registration from the server.
+		await sendResponse(client, message.id, null, message.method);
+		return;
+	}
+	if (message.method === "client/registerCapability" || message.method === "client/unregisterCapability") {
+		// Some servers block semantic requests until dynamic registration succeeds.
+		await sendResponse(client, message.id, null, message.method);
 		return;
 	}
-	if (typeof message.id !== "number") return;
 	await sendResponse(client, message.id, null, message.method, {
 		code: -32601,
 		message: `Method not found: ${message.method}`,
@@ -493,7 +493,7 @@ async function handleServerRequest(client: LspClient, message: LspJsonRpcRequest
  */
 async function sendResponse(
 	client: LspClient,
-	id: number,
+	id: LspJsonRpcId,
 	result: unknown,
 	method: string,
 	error?: { code: number; message: string; data?: unknown },

packages/coding-agent/src/lsp/types.ts

@@ -399,7 +399,7 @@ export interface LspClient {
 	diagnostics: Map<string, PublishedDiagnostics>;
 	diagnosticsVersion: number;
 	openFiles: Map<string, OpenFile>;
-	pendingRequests: Map<number, PendingRequest>;
+	pendingRequests: Map<number | string, PendingRequest>;
 	messageBuffer: Uint8Array;
 	isReading: boolean;
 	/** Lifecycle state: "connecting" until initialize completes, then "ready"; "error" on init failure or reader death. */
@@ -420,16 +420,19 @@ export interface LspClient {
 // JSON-RPC Protocol Types
 // =============================================================================
 
+/** JSON-RPC request/response identifier accepted by LSP peers. */
+export type LspJsonRpcId = number | string;
+
 export interface LspJsonRpcRequest {
 	jsonrpc: "2.0";
-	id: number;
+	id: LspJsonRpcId;
 	method: string;
 	params: unknown;
 }
 
 export interface LspJsonRpcResponse {
 	jsonrpc: "2.0";
-	id?: number;
+	id?: LspJsonRpcId;
 	result?: unknown;
 	error?: { code: number; message: string; data?: unknown };
 }

packages/coding-agent/test/tools/lsp-regressions.test.ts

@@ -308,6 +308,78 @@ describe("lsp regressions", () => {
 		}
 	});
 
+	it("accepts dynamic capability registration before semantic requests", async () => {
+		const tempDir = TempDir.createSync("@omp-lsp-dynamic-registration-");
+		try {
+			let dynamicRegistrationAccepted = false;
+			const server = installFakeLsp((message, srv) => {
+				if (message.method === "initialize") {
+					srv.send({ jsonrpc: "2.0", id: message.id, result: { capabilities: { hoverProvider: true } } });
+				} else if (message.method === "initialized") {
+					srv.send({
+						jsonrpc: "2.0",
+						id: 9002,
+						method: "client/registerCapability",
+						params: {
+							registrations: [
+								{
+									id: "-42",
+									method: "workspace/didChangeWatchedFiles",
+									registerOptions: {
+										watchers: [{ globPattern: "**/mix.lock" }, { globPattern: "**/*.{ex,exs}" }],
+									},
+								},
+							],
+						},
+					});
+					srv.send({
+						jsonrpc: "2.0",
+						id: "expert-unregister-1",
+						method: "client/unregisterCapability",
+						params: { unregisterations: [{ id: "-42", method: "workspace/didChangeWatchedFiles" }] },
+					});
+				} else if (message.id === 9002 && message.method === undefined) {
+					dynamicRegistrationAccepted = message.error === undefined;
+				} else if (message.method === "textDocument/hover" && dynamicRegistrationAccepted) {
+					srv.send({ jsonrpc: "2.0", id: message.id, result: { contents: "Atas.version()" } });
+				} else if (message.method === "shutdown") {
+					srv.send({ jsonrpc: "2.0", id: message.id, result: null });
+				} else if (message.method === "exit") {
+					srv.exit(0);
+				}
+			});
+
+			const config: ServerConfig = {
+				command: "fake-lsp",
+				fileTypes: ["ex"],
+				rootMarkers: [],
+			};
+
+			const client = await lspClient.getOrCreateClient(config, tempDir.path(), 1_000);
+			const registerResponse = await server.waitFor(message => message.id === 9002 && message.method === undefined);
+			const unregisterResponse = await server.waitFor(
+				message => message.id === "expert-unregister-1" && message.method === undefined,
+			);
+			expect(registerResponse.error).toBeUndefined();
+			expect(unregisterResponse.error).toBeUndefined();
+			const result = await lspClient.sendRequest(
+				client,
+				"textDocument/hover",
+				{
+					textDocument: { uri: fileToUri(path.join(tempDir.path(), "lib", "atas.ex")) },
+					position: { line: 0, character: 0 },
+				},
+				undefined,
+				50,
+			);
+
+			expect(result).toEqual({ contents: "Atas.version()" });
+		} finally {
+			await lspClient.shutdownAll();
+			tempDir.removeSync();
+		}
+	});
+
 	it("opens rust-analyzer Cargo workspace files before polling workspace readiness", async () => {
 		const tempDir = TempDir.createSync("@omp-lsp-rust-workspace-");
 		try {