fix(cursor): exposed mounted xd devices to cursor-agent

Forwarded the session xd registry into Cursor provider tool contexts.

Routed Cursor MCP execution through the mounted registry fallback and added regression coverage for built-in devices and external MCP tools.

Fixes #5650

packages/agent/test/agent-side-request-context.test.ts

@@ -2,6 +2,7 @@ import { describe, expect, it, mock } from "bun:test";
 import { type AssistantMessage, type Context, z } from "@oh-my-pi/pi-ai";
 import { createMockModel } from "@oh-my-pi/pi-ai/providers/mock";
 import { AssistantMessageEventStream } from "@oh-my-pi/pi-ai/utils/event-stream";
+import { buildModel } from "@oh-my-pi/pi-catalog/build";
 import { Agent } from "../src/agent";
 import type { AgentTool } from "../src/types";
 
@@ -39,6 +40,19 @@ function testAssistantMessage(text: string): AssistantMessage {
 	};
 }
 
+const cursorModel = buildModel({
+	id: "cursor-test",
+	name: "Cursor Test",
+	api: "cursor-agent",
+	provider: "cursor",
+	baseUrl: "https://example.invalid",
+	reasoning: false,
+	input: ["text"],
+	cost: { input: 0, output: 0, cacheRead: 0, cacheWrite: 0 },
+	contextWindow: 8_192,
+	maxTokens: 2_048,
+});
+
 describe("Agent — buildSideRequestContext", () => {
 	const model = createMockModel({ responses: [] });
 	const tool: AgentTool = {
@@ -109,6 +123,43 @@ describe("Agent — buildSideRequestContext", () => {
 		});
 	});
 
+	it("adds mounted Cursor tools to main and side provider contexts", async () => {
+		await withNativeDialectEnv(async () => {
+			const mountedTool: AgentTool = {
+				...tool,
+				name: "mcp__fixture_report",
+				label: "Fixture Report",
+			};
+			let mainContext: Context | undefined;
+			const agent = new Agent({
+				initialState: {
+					model: cursorModel,
+					systemPrompt: ["system"],
+					tools: [tool],
+				},
+				getCursorTools: () => [tool, mountedTool],
+				streamFn: (_model, context) => {
+					mainContext = context;
+					const stream = new AssistantMessageEventStream();
+					queueMicrotask(() => {
+						const message = testAssistantMessage("ok");
+						stream.push({ type: "text_delta", contentIndex: 0, delta: "ok", partial: message });
+						stream.push({ type: "done", reason: "stop", message });
+					});
+					return stream;
+				},
+			});
+
+			await agent.prompt("Q?");
+			const sideContext = await agent.buildSideRequestContext([
+				{ role: "user", content: [{ type: "text", text: "Q?" }], timestamp: Date.now() },
+			]);
+
+			expect(mainContext?.tools?.map(entry => entry.name)).toEqual(["test_tool", "mcp__fixture_report"]);
+			expect(sideContext.tools?.map(entry => entry.name)).toEqual(["test_tool", "mcp__fixture_report"]);
+		});
+	});
+
 	it("returns empty tools when owned dialect is active", async () => {
 		const agent = new Agent({
 			initialState: {