diff --git a/src/cursor/cursor-executor.ts b/src/cursor/cursor-executor.ts
new file mode 100644
index 00000000..28ce9f55
--- /dev/null
+++ b/src/cursor/cursor-executor.ts
@@ -0,0 +1,786 @@
+/**
+ * Cursor Executor
+ * Handles HTTP/2 requests to Cursor API with protobuf encoding/decoding
+ */
+
+import * as crypto from "crypto";
+import * as zlib from "zlib";
+import type { IncomingHttpHeaders } from "http";
+import { generateCursorBody, extractTextFromResponse } from "./cursor-protobuf.js";
+import { buildCursorRequest } from "./cursor-translator.js";
+import type { CursorMessage, CursorTool } from "./cursor-protobuf-schema.js";
+
+/** Compression flags for response parsing */
+const COMPRESS_FLAG = {
+	NONE: 0x00,
+	GZIP: 0x01,
+	GZIP_ALT: 0x02,
+	GZIP_BOTH: 0x03,
+} as const;
+
+/** Cursor credentials structure */
+interface CursorCredentials {
+	accessToken: string;
+	providerSpecificData?: {
+		machineId?: string;
+		ghostMode?: boolean;
+	};
+}
+
+/** Executor parameters */
+interface ExecutorParams {
+	model: string;
+	body: {
+		messages: Array<{
+			role: string;
+			content: string | Array<{ type: string; text?: string }>;
+			name?: string;
+			tool_call_id?: string;
+			tool_calls?: Array<{
+				id: string;
+				type: string;
+				function: { name: string; arguments: string };
+			}>;
+		}>;
+		tools?: CursorTool[];
+		reasoning_effort?: string;
+	};
+	stream: boolean;
+	credentials: CursorCredentials;
+	signal?: AbortSignal;
+}
+
+/** HTTP/2 response structure */
+interface Http2Response {
+	status: number;
+	headers: IncomingHttpHeaders;
+	body: Buffer;
+}
+
+/** Detect cloud environment */
+function isCloudEnv(): boolean {
+	if (typeof caches !== "undefined" && typeof caches === "object") return true;
+	try {
+		// Check for EdgeRuntime without causing compilation error
+		if (typeof (globalThis as { EdgeRuntime?: string }).EdgeRuntime !== "undefined") return true;
+	} catch {
+		// Continue
+	}
+	return false;
+}
+
+/** Lazy import http2 */
+let http2Module: typeof import("http2") | null = null;
+async function getHttp2() {
+	if (http2Module) return http2Module;
+	if (!isCloudEnv()) {
+		try {
+			http2Module = await import("http2");
+			return http2Module;
+		} catch {
+			return null;
+		}
+	}
+	return null;
+}
+
+/**
+ * Decompress payload if needed
+ */
+function decompressPayload(payload: Buffer, flags: number): Buffer {
+	// Check if payload is JSON error
+	if (payload.length > 10 && payload[0] === 0x7b && payload[1] === 0x22) {
+		try {
+			const text = payload.toString("utf-8");
+			if (text.startsWith('{"error"')) {
+				return payload;
+			}
+		} catch {
+			// Continue
+		}
+	}
+
+	if (
+		flags === COMPRESS_FLAG.GZIP ||
+		flags === COMPRESS_FLAG.GZIP_ALT ||
+		flags === COMPRESS_FLAG.GZIP_BOTH
+	) {
+		try {
+			return zlib.gunzipSync(payload);
+		} catch {
+			return payload;
+		}
+	}
+	return payload;
+}
+
+/**
+ * Create error response from JSON error
+ */
+function createErrorResponse(jsonError: {
+	error?: {
+		code?: string;
+		message?: string;
+		details?: Array<{ debug?: { details?: { title?: string; detail?: string }; error?: string } }>;
+	};
+}): Response {
+	const errorMsg =
+		jsonError?.error?.details?.[0]?.debug?.details?.title ||
+		jsonError?.error?.details?.[0]?.debug?.details?.detail ||
+		jsonError?.error?.message ||
+		"API Error";
+
+	const isRateLimit = jsonError?.error?.code === "resource_exhausted";
+
+	return new Response(
+		JSON.stringify({
+			error: {
+				message: errorMsg,
+				type: isRateLimit ? "rate_limit_error" : "api_error",
+				code: jsonError?.error?.details?.[0]?.debug?.error || "unknown",
+			},
+		}),
+		{
+			status: isRateLimit ? 429 : 400,
+			headers: { "Content-Type": "application/json" },
+		}
+	);
+}
+
+export class CursorExecutor {
+	private readonly baseUrl = "https://api2.cursor.sh";
+	private readonly chatPath = "/aiserver.v1.AiService/StreamChat";
+
+	buildUrl(): string {
+		return `${this.baseUrl}${this.chatPath}`;
+	}
+
+	/**
+	 * Generate checksum using Jyh cipher (time-based XOR with rolling key seed=165)
+	 */
+	generateChecksum(machineId: string): string {
+		const timestamp = Math.floor(Date.now() / 1000000);
+		const byteArray = new Uint8Array([
+			(timestamp >> 40) & 0xff,
+			(timestamp >> 32) & 0xff,
+			(timestamp >> 24) & 0xff,
+			(timestamp >> 16) & 0xff,
+			(timestamp >> 8) & 0xff,
+			timestamp & 0xff,
+		]);
+
+		let t = 165;
+		for (let i = 0; i < byteArray.length; i++) {
+			byteArray[i] = ((byteArray[i] ^ t) + (i % 256)) & 0xff;
+			t = byteArray[i];
+		}
+
+		const alphabet = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_";
+		let encoded = "";
+
+		for (let i = 0; i < byteArray.length; i += 3) {
+			const a = byteArray[i];
+			const b = i + 1 < byteArray.length ? byteArray[i + 1] : 0;
+			const c = i + 2 < byteArray.length ? byteArray[i + 2] : 0;
+
+			encoded += alphabet[a >> 2];
+			encoded += alphabet[((a & 3) << 4) | (b >> 4)];
+
+			if (i + 1 < byteArray.length) {
+				encoded += alphabet[((b & 15) << 2) | (c >> 6)];
+			}
+			if (i + 2 < byteArray.length) {
+				encoded += alphabet[c & 63];
+			}
+		}
+
+		return `${encoded}${machineId}`;
+	}
+
+	buildHeaders(credentials: CursorCredentials): Record<string, string> {
+		const accessToken = credentials.accessToken;
+		const machineId = credentials.providerSpecificData?.machineId;
+		const ghostMode = credentials.providerSpecificData?.ghostMode !== false;
+
+		if (!machineId) {
+			throw new Error("Machine ID is required for Cursor API");
+		}
+
+		const cleanToken = accessToken.includes("::")
+			? accessToken.split("::")[1]
+			: accessToken;
+
+		return {
+			authorization: `Bearer ${cleanToken}`,
+			"connect-accept-encoding": "gzip",
+			"connect-protocol-version": "1",
+			"content-type": "application/connect+proto",
+			"user-agent": "connect-es/1.6.1",
+			"x-amzn-trace-id": `Root=${crypto.randomUUID()}`,
+			"x-client-key": crypto.createHash("sha256").update(cleanToken).digest("hex"),
+			"x-cursor-checksum": this.generateChecksum(machineId),
+			"x-cursor-client-version": "2.3.41",
+			"x-cursor-client-type": "ide",
+			"x-cursor-client-os":
+				process.platform === "win32"
+					? "windows"
+					: process.platform === "darwin"
+						? "macos"
+						: "linux",
+			"x-cursor-client-arch": process.arch === "arm64" ? "aarch64" : "x64",
+			"x-cursor-client-device-type": "desktop",
+			"x-cursor-config-version": crypto.randomUUID(),
+			"x-cursor-timezone":
+				Intl.DateTimeFormat().resolvedOptions().timeZone || "UTC",
+			"x-ghost-mode": ghostMode ? "true" : "false",
+			"x-request-id": crypto.randomUUID(),
+			"x-session-id": crypto
+				.createHash("sha256")
+				.update(cleanToken)
+				.digest("hex")
+				.substring(0, 36),
+		};
+	}
+
+	transformRequest(
+		model: string,
+		body: ExecutorParams["body"],
+		stream: boolean,
+		credentials: CursorCredentials
+	): Uint8Array {
+		const translatedBody = buildCursorRequest(model, body, stream, credentials);
+		const messages = translatedBody.messages || [];
+		const tools = (translatedBody.tools || body.tools || []) as CursorTool[];
+		const reasoningEffort = body.reasoning_effort || null;
+		return generateCursorBody(messages, model, tools, reasoningEffort);
+	}
+
+	async makeFetchRequest(
+		url: string,
+		headers: Record<string, string>,
+		body: Uint8Array,
+		signal?: AbortSignal
+	): Promise<Http2Response> {
+		const response = await fetch(url, {
+			method: "POST",
+			headers,
+			body,
+			signal,
+		});
+
+		const responseHeaders: Record<string, string> = {};
+		response.headers.forEach((value, key) => {
+			responseHeaders[key] = value;
+		});
+
+		return {
+			status: response.status,
+			headers: responseHeaders,
+			body: Buffer.from(await response.arrayBuffer()),
+		};
+	}
+
+	async makeHttp2Request(
+		url: string,
+		headers: Record<string, string>,
+		body: Uint8Array,
+		signal?: AbortSignal
+	): Promise<Http2Response> {
+		const http2 = await getHttp2();
+		if (!http2) {
+			throw new Error("http2 module not available");
+		}
+
+		return new Promise((resolve, reject) => {
+			const urlObj = new URL(url);
+			const client = http2.connect(`https://${urlObj.host}`);
+			const chunks: Buffer[] = [];
+			let responseHeaders: IncomingHttpHeaders = {};
+
+			client.on("error", reject);
+
+			const req = client.request({
+				":method": "POST",
+				":path": urlObj.pathname,
+				":authority": urlObj.host,
+				":scheme": "https",
+				...headers,
+			});
+
+			req.on("response", (hdrs) => {
+				responseHeaders = hdrs;
+			});
+			req.on("data", (chunk: Buffer) => {
+				chunks.push(chunk);
+			});
+			req.on("end", () => {
+				client.close();
+				resolve({
+					status: Number(responseHeaders[":status"]),
+					headers: responseHeaders,
+					body: Buffer.concat(chunks),
+				});
+			});
+			req.on("error", (err) => {
+				client.close();
+				reject(err);
+			});
+
+			if (signal) {
+				signal.addEventListener("abort", () => {
+					req.close();
+					client.close();
+					reject(new Error("Request aborted"));
+				});
+			}
+
+			req.write(body);
+			req.end();
+		});
+	}
+
+	async execute(params: ExecutorParams): Promise<{
+		response: Response;
+		url: string;
+		headers: Record<string, string>;
+		transformedBody: ExecutorParams["body"];
+	}> {
+		const { model, body, stream, credentials, signal } = params;
+		const url = this.buildUrl();
+		const headers = this.buildHeaders(credentials);
+		const transformedBody = this.transformRequest(model, body, stream, credentials);
+
+		try {
+			const http2 = await getHttp2();
+			const response = http2
+				? await this.makeHttp2Request(url, headers, transformedBody, signal)
+				: await this.makeFetchRequest(url, headers, transformedBody, signal);
+
+			if (response.status !== 200) {
+				const errorText = response.body?.toString() || "Unknown error";
+				const errorResponse = new Response(
+					JSON.stringify({
+						error: {
+							message: `[${response.status}]: ${errorText}`,
+							type: "invalid_request_error",
+							code: "",
+						},
+					}),
+					{
+						status: response.status,
+						headers: { "Content-Type": "application/json" },
+					}
+				);
+				return { response: errorResponse, url, headers, transformedBody: body };
+			}
+
+			const transformedResponse =
+				stream !== false
+					? this.transformProtobufToSSE(response.body, model, body)
+					: this.transformProtobufToJSON(response.body, model, body);
+
+			return { response: transformedResponse, url, headers, transformedBody: body };
+		} catch (error) {
+			const errorResponse = new Response(
+				JSON.stringify({
+					error: {
+						message: (error as Error).message,
+						type: "connection_error",
+						code: "",
+					},
+				}),
+				{
+					status: 500,
+					headers: { "Content-Type": "application/json" },
+				}
+			);
+			return { response: errorResponse, url, headers, transformedBody: body };
+		}
+	}
+
+	transformProtobufToJSON(
+		buffer: Buffer,
+		model: string,
+		body: ExecutorParams["body"]
+	): Response {
+		const responseId = `chatcmpl-cursor-${Date.now()}`;
+		const created = Math.floor(Date.now() / 1000);
+
+		let offset = 0;
+		let totalContent = "";
+		const toolCalls: Array<{
+			id: string;
+			type: string;
+			function: { name: string; arguments: string };
+		}> = [];
+		const toolCallsMap = new Map<
+			string,
+			{
+				id: string;
+				type: string;
+				function: { name: string; arguments: string };
+				isLast: boolean;
+				index: number;
+			}
+		>();
+
+		while (offset < buffer.length) {
+			if (offset + 5 > buffer.length) break;
+
+			const flags = buffer[offset];
+			const length = buffer.readUInt32BE(offset + 1);
+
+			if (offset + 5 + length > buffer.length) break;
+
+			let payload = buffer.slice(offset + 5, offset + 5 + length);
+			offset += 5 + length;
+
+			payload = decompressPayload(payload, flags);
+
+			try {
+				const text = payload.toString("utf-8");
+				if (text.startsWith("{") && text.includes('"error"')) {
+					return createErrorResponse(JSON.parse(text));
+				}
+			} catch {
+				// Continue
+			}
+
+			const result = extractTextFromResponse(new Uint8Array(payload));
+
+			if (result.error) {
+				return new Response(
+					JSON.stringify({
+						error: {
+							message: result.error,
+							type: "rate_limit_error",
+							code: "rate_limited",
+						},
+					}),
+					{
+						status: 429,
+						headers: { "Content-Type": "application/json" },
+					}
+				);
+			}
+
+			if (result.toolCall) {
+				const tc = result.toolCall;
+
+				if (toolCallsMap.has(tc.id)) {
+					const existing = toolCallsMap.get(tc.id)!;
+					existing.function.arguments += tc.function.arguments;
+					existing.isLast = tc.isLast;
+				} else {
+					toolCallsMap.set(tc.id, {
+						...tc,
+						index: toolCallsMap.size,
+					});
+				}
+
+				if (tc.isLast) {
+					const finalToolCall = toolCallsMap.get(tc.id)!;
+					toolCalls.push({
+						id: finalToolCall.id,
+						type: finalToolCall.type,
+						function: {
+							name: finalToolCall.function.name,
+							arguments: finalToolCall.function.arguments,
+						},
+					});
+				}
+			}
+
+			if (result.text) totalContent += result.text;
+		}
+
+		// Finalize remaining tool calls
+		for (const id of Array.from(toolCallsMap.keys())) {
+			const tc = toolCallsMap.get(id)!;
+			if (!toolCalls.find((t) => t.id === id)) {
+				toolCalls.push({
+					id: tc.id,
+					type: tc.type,
+					function: {
+						name: tc.function.name,
+						arguments: tc.function.arguments,
+					},
+				});
+			}
+		}
+
+		const message: {
+			role: string;
+			content: string | null;
+			tool_calls?: Array<{
+				id: string;
+				type: string;
+				function: { name: string; arguments: string };
+			}>;
+		} = {
+			role: "assistant",
+			content: totalContent || null,
+		};
+
+		if (toolCalls.length > 0) {
+			message.tool_calls = toolCalls;
+		}
+
+		const completion = {
+			id: responseId,
+			object: "chat.completion",
+			created,
+			model,
+			choices: [
+				{
+					index: 0,
+					message,
+					finish_reason: toolCalls.length > 0 ? "tool_calls" : "stop",
+				},
+			],
+			usage: {
+				prompt_tokens: 0,
+				completion_tokens: 0,
+				total_tokens: 0,
+			},
+		};
+
+		return new Response(JSON.stringify(completion), {
+			status: 200,
+			headers: { "Content-Type": "application/json" },
+		});
+	}
+
+	transformProtobufToSSE(
+		buffer: Buffer,
+		model: string,
+		body: ExecutorParams["body"]
+	): Response {
+		const responseId = `chatcmpl-cursor-${Date.now()}`;
+		const created = Math.floor(Date.now() / 1000);
+
+		const chunks: string[] = [];
+		let offset = 0;
+		let totalContent = "";
+		const toolCalls: Array<{
+			id: string;
+			type: string;
+			function: { name: string; arguments: string };
+			index: number;
+		}> = [];
+		const toolCallsMap = new Map<
+			string,
+			{
+				id: string;
+				type: string;
+				function: { name: string; arguments: string };
+				isLast: boolean;
+				index: number;
+			}
+		>();
+
+		while (offset < buffer.length) {
+			if (offset + 5 > buffer.length) break;
+
+			const flags = buffer[offset];
+			const length = buffer.readUInt32BE(offset + 1);
+
+			if (offset + 5 + length > buffer.length) break;
+
+			let payload = buffer.slice(offset + 5, offset + 5 + length);
+			offset += 5 + length;
+
+			payload = decompressPayload(payload, flags);
+
+			try {
+				const text = payload.toString("utf-8");
+				if (text.startsWith("{") && text.includes('"error"')) {
+					return createErrorResponse(JSON.parse(text));
+				}
+			} catch {
+				// Continue
+			}
+
+			const result = extractTextFromResponse(new Uint8Array(payload));
+
+			if (result.error) {
+				return new Response(
+					JSON.stringify({
+						error: {
+							message: result.error,
+							type: "rate_limit_error",
+							code: "rate_limited",
+						},
+					}),
+					{
+						status: 429,
+						headers: { "Content-Type": "application/json" },
+					}
+				);
+			}
+
+			if (result.toolCall) {
+				const tc = result.toolCall;
+
+				if (chunks.length === 0) {
+					chunks.push(
+						`data: ${JSON.stringify({
+							id: responseId,
+							object: "chat.completion.chunk",
+							created,
+							model,
+							choices: [
+								{
+									index: 0,
+									delta: { role: "assistant", content: "" },
+									finish_reason: null,
+								},
+							],
+						})}\n\n`
+					);
+				}
+
+				if (toolCallsMap.has(tc.id)) {
+					const existing = toolCallsMap.get(tc.id)!;
+					existing.function.arguments += tc.function.arguments;
+					existing.isLast = tc.isLast;
+
+					if (tc.function.arguments) {
+						chunks.push(
+							`data: ${JSON.stringify({
+								id: responseId,
+								object: "chat.completion.chunk",
+								created,
+								model,
+								choices: [
+									{
+										index: 0,
+										delta: {
+											tool_calls: [
+												{
+													index: existing.index,
+													id: tc.id,
+													type: "function",
+													function: {
+														name: tc.function.name,
+														arguments: tc.function.arguments,
+													},
+												},
+											],
+										},
+										finish_reason: null,
+									},
+								],
+							})}\n\n`
+						);
+					}
+				} else {
+					const toolCallIndex = toolCalls.length;
+					toolCalls.push({ ...tc, index: toolCallIndex });
+					toolCallsMap.set(tc.id, { ...tc, index: toolCallIndex });
+
+					chunks.push(
+						`data: ${JSON.stringify({
+							id: responseId,
+							object: "chat.completion.chunk",
+							created,
+							model,
+							choices: [
+								{
+									index: 0,
+									delta: {
+										tool_calls: [
+											{
+												index: toolCallIndex,
+												id: tc.id,
+												type: "function",
+												function: {
+													name: tc.function.name,
+													arguments: tc.function.arguments,
+												},
+											},
+										],
+									},
+									finish_reason: null,
+								},
+							],
+						})}\n\n`
+					);
+				}
+			}
+
+			if (result.text) {
+				totalContent += result.text;
+				chunks.push(
+					`data: ${JSON.stringify({
+						id: responseId,
+						object: "chat.completion.chunk",
+						created,
+						model,
+						choices: [
+							{
+								index: 0,
+								delta:
+									chunks.length === 0 && toolCalls.length === 0
+										? { role: "assistant", content: result.text }
+										: { content: result.text },
+								finish_reason: null,
+							},
+						],
+					})}\n\n`
+				);
+			}
+		}
+
+		if (chunks.length === 0 && toolCalls.length === 0) {
+			chunks.push(
+				`data: ${JSON.stringify({
+					id: responseId,
+					object: "chat.completion.chunk",
+					created,
+					model,
+					choices: [
+						{
+							index: 0,
+							delta: { role: "assistant", content: "" },
+							finish_reason: null,
+						},
+					],
+				})}\n\n`
+			);
+		}
+
+		chunks.push(
+			`data: ${JSON.stringify({
+				id: responseId,
+				object: "chat.completion.chunk",
+				created,
+				model,
+				choices: [
+					{
+						index: 0,
+						delta: {},
+						finish_reason: toolCalls.length > 0 ? "tool_calls" : "stop",
+					},
+				],
+				usage: {
+					prompt_tokens: 0,
+					completion_tokens: 0,
+					total_tokens: 0,
+				},
+			})}\n\n`
+		);
+		chunks.push("data: [DONE]\n\n");
+
+		return new Response(chunks.join(""), {
+			status: 200,
+			headers: {
+				"Content-Type": "text/event-stream",
+				"Cache-Control": "no-cache",
+				Connection: "keep-alive",
+			},
+		});
+	}
+}
+
+export default CursorExecutor;
diff --git a/src/cursor/cursor-protobuf-decoder.ts b/src/cursor/cursor-protobuf-decoder.ts
new file mode 100644
index 00000000..7b3e0d6a
--- /dev/null
+++ b/src/cursor/cursor-protobuf-decoder.ts
@@ -0,0 +1,301 @@
+/**
+ * Cursor Protobuf Decoder
+ * Implements ConnectRPC protobuf wire format decoding
+ */
+
+import * as zlib from "zlib";
+import {
+	WIRE_TYPE,
+	FIELD,
+	type WireType,
+} from "./cursor-protobuf-schema.js";
+
+/**
+ * Decode a varint from buffer
+ * Returns [value, newOffset]
+ */
+export function decodeVarint(
+	buffer: Uint8Array,
+	offset: number
+): [number, number] {
+	let result = 0;
+	let shift = 0;
+	let pos = offset;
+
+	while (pos < buffer.length) {
+		const b = buffer[pos];
+		result |= (b & 0x7f) << shift;
+		pos++;
+		if (!(b & 0x80)) break;
+		shift += 7;
+	}
+
+	return [result, pos];
+}
+
+/**
+ * Decode a single protobuf field
+ * Returns [fieldNum, wireType, value, newOffset]
+ */
+export function decodeField(
+	buffer: Uint8Array,
+	offset: number
+): [number | null, WireType | null, Uint8Array | number | null, number] {
+	if (offset >= buffer.length) {
+		return [null, null, null, offset];
+	}
+
+	const [tag, pos1] = decodeVarint(buffer, offset);
+	const fieldNum = tag >> 3;
+	const wireType = (tag & 0x07) as WireType;
+
+	let value: Uint8Array | number | null;
+	let pos = pos1;
+
+	if (wireType === WIRE_TYPE.VARINT) {
+		[value, pos] = decodeVarint(buffer, pos);
+	} else if (wireType === WIRE_TYPE.LEN) {
+		const [length, pos2] = decodeVarint(buffer, pos);
+		value = buffer.slice(pos2, pos2 + length);
+		pos = pos2 + length;
+	} else if (wireType === WIRE_TYPE.FIXED64) {
+		value = buffer.slice(pos, pos + 8);
+		pos += 8;
+	} else if (wireType === WIRE_TYPE.FIXED32) {
+		value = buffer.slice(pos, pos + 4);
+		pos += 4;
+	} else {
+		value = null;
+	}
+
+	return [fieldNum, wireType, value, pos];
+}
+
+/**
+ * Decode a protobuf message into a map of fields
+ */
+export function decodeMessage(
+	data: Uint8Array
+): Map<number, Array<{ wireType: WireType; value: Uint8Array | number }>> {
+	const fields = new Map<
+		number,
+		Array<{ wireType: WireType; value: Uint8Array | number }>
+	>();
+	let pos = 0;
+
+	while (pos < data.length) {
+		const [fieldNum, wireType, value, newPos] = decodeField(data, pos);
+		if (fieldNum === null || wireType === null || value === null) break;
+
+		if (!fields.has(fieldNum)) {
+			fields.set(fieldNum, []);
+		}
+		fields.get(fieldNum)!.push({ wireType, value: value as Uint8Array | number });
+		pos = newPos;
+	}
+
+	return fields;
+}
+
+/**
+ * Parse ConnectRPC frame from buffer
+ * Returns frame data or null if incomplete
+ */
+export function parseConnectRPCFrame(buffer: Buffer): {
+	flags: number;
+	length: number;
+	payload: Uint8Array;
+	consumed: number;
+} | null {
+	if (buffer.length < 5) return null;
+
+	const flags = buffer[0];
+	const length =
+		(buffer[1] << 24) | (buffer[2] << 16) | (buffer[3] << 8) | buffer[4];
+
+	if (buffer.length < 5 + length) return null;
+
+	let payload = buffer.slice(5, 5 + length);
+
+	// Decompress if gzip
+	if (flags === 0x01 || flags === 0x02 || flags === 0x03) {
+		try {
+			payload = Buffer.from(zlib.gunzipSync(payload));
+		} catch {
+			// Decompression failed, use raw payload
+		}
+	}
+
+	return {
+		flags,
+		length,
+		payload: new Uint8Array(payload),
+		consumed: 5 + length,
+	};
+}
+
+/**
+ * Extract tool call from protobuf data
+ */
+function extractToolCall(toolCallData: Uint8Array): {
+	id: string;
+	type: string;
+	function: { name: string; arguments: string };
+	isLast: boolean;
+} | null {
+	const toolCall = decodeMessage(toolCallData);
+	let toolCallId = "";
+	let toolName = "";
+	let rawArgs = "";
+	let isLast = false;
+
+	// Extract tool call ID
+	if (toolCall.has(FIELD.TOOL_ID)) {
+		const fullId = new TextDecoder().decode(
+			toolCall.get(FIELD.TOOL_ID)![0].value as Uint8Array
+		);
+		toolCallId = fullId.split("\n")[0]; // Take first line
+	}
+
+	// Extract tool name
+	if (toolCall.has(FIELD.TOOL_NAME)) {
+		toolName = new TextDecoder().decode(
+			toolCall.get(FIELD.TOOL_NAME)![0].value as Uint8Array
+		);
+	}
+
+	// Extract is_last flag
+	if (toolCall.has(FIELD.TOOL_IS_LAST)) {
+		isLast = (toolCall.get(FIELD.TOOL_IS_LAST)![0].value as number) !== 0;
+	}
+
+	// Extract MCP params - nested real tool info
+	if (toolCall.has(FIELD.TOOL_MCP_PARAMS)) {
+		try {
+			const mcpParams = decodeMessage(
+				toolCall.get(FIELD.TOOL_MCP_PARAMS)![0].value as Uint8Array
+			);
+
+			if (mcpParams.has(FIELD.MCP_TOOLS_LIST)) {
+				const tool = decodeMessage(
+					mcpParams.get(FIELD.MCP_TOOLS_LIST)![0].value as Uint8Array
+				);
+
+				if (tool.has(FIELD.MCP_NESTED_NAME)) {
+					toolName = new TextDecoder().decode(
+						tool.get(FIELD.MCP_NESTED_NAME)![0].value as Uint8Array
+					);
+				}
+
+				if (tool.has(FIELD.MCP_NESTED_PARAMS)) {
+					rawArgs = new TextDecoder().decode(
+						tool.get(FIELD.MCP_NESTED_PARAMS)![0].value as Uint8Array
+					);
+				}
+			}
+		} catch {
+			// MCP parse error, continue
+		}
+	}
+
+	// Fallback to raw_args
+	if (!rawArgs && toolCall.has(FIELD.TOOL_RAW_ARGS)) {
+		rawArgs = new TextDecoder().decode(
+			toolCall.get(FIELD.TOOL_RAW_ARGS)![0].value as Uint8Array
+		);
+	}
+
+	if (toolCallId && toolName) {
+		return {
+			id: toolCallId,
+			type: "function",
+			function: {
+				name: toolName,
+				arguments: rawArgs || "{}",
+			},
+			isLast,
+		};
+	}
+
+	return null;
+}
+
+/**
+ * Extract text and thinking from response data
+ */
+function extractTextAndThinking(
+	responseData: Uint8Array
+): { text: string | null; thinking: string | null } {
+	const nested = decodeMessage(responseData);
+	let text: string | null = null;
+	let thinking: string | null = null;
+
+	// Extract text
+	if (nested.has(FIELD.RESPONSE_TEXT)) {
+		text = new TextDecoder().decode(
+			nested.get(FIELD.RESPONSE_TEXT)![0].value as Uint8Array
+		);
+	}
+
+	// Extract thinking
+	if (nested.has(FIELD.THINKING)) {
+		try {
+			const thinkingMsg = decodeMessage(
+				nested.get(FIELD.THINKING)![0].value as Uint8Array
+			);
+			if (thinkingMsg.has(FIELD.THINKING_TEXT)) {
+				thinking = new TextDecoder().decode(
+					thinkingMsg.get(FIELD.THINKING_TEXT)![0].value as Uint8Array
+				);
+			}
+		} catch {
+			// Thinking parse error, continue
+		}
+	}
+
+	return { text, thinking };
+}
+
+/**
+ * Extract text and tool calls from response payload
+ */
+export function extractTextFromResponse(payload: Uint8Array): {
+	text: string | null;
+	error: string | null;
+	toolCall: {
+		id: string;
+		type: string;
+		function: { name: string; arguments: string };
+		isLast: boolean;
+	} | null;
+	thinking: string | null;
+} {
+	try {
+		const fields = decodeMessage(payload);
+
+		// Field 1: ClientSideToolV2Call
+		if (fields.has(FIELD.TOOL_CALL)) {
+			const toolCall = extractToolCall(
+				fields.get(FIELD.TOOL_CALL)![0].value as Uint8Array
+			);
+			if (toolCall) {
+				return { text: null, error: null, toolCall, thinking: null };
+			}
+		}
+
+		// Field 2: StreamUnifiedChatResponse
+		if (fields.has(FIELD.RESPONSE)) {
+			const { text, thinking } = extractTextAndThinking(
+				fields.get(FIELD.RESPONSE)![0].value as Uint8Array
+			);
+
+			if (text || thinking) {
+				return { text, error: null, toolCall: null, thinking };
+			}
+		}
+
+		return { text: null, error: null, toolCall: null, thinking: null };
+	} catch {
+		return { text: null, error: null, toolCall: null, thinking: null };
+	}
+}
diff --git a/src/cursor/cursor-protobuf-encoder.ts b/src/cursor/cursor-protobuf-encoder.ts
new file mode 100644
index 00000000..6958d219
--- /dev/null
+++ b/src/cursor/cursor-protobuf-encoder.ts
@@ -0,0 +1,262 @@
+/**
+ * Cursor Protobuf Encoder
+ * Implements ConnectRPC protobuf wire format encoding
+ */
+
+import { randomUUID } from "crypto";
+import * as zlib from "zlib";
+import {
+	WIRE_TYPE,
+	ROLE,
+	UNIFIED_MODE,
+	THINKING_LEVEL,
+	FIELD,
+	COMPRESS_FLAG,
+	type WireType,
+	type RoleType,
+	type ThinkingLevelType,
+	type CursorTool,
+	type CursorToolResult,
+	type CursorMessage,
+	type FormattedMessage,
+	type MessageId,
+} from "./cursor-protobuf-schema.js";
+
+/**
+ * Encode a varint (variable-length integer)
+ */
+export function encodeVarint(value: number): Uint8Array {
+	const bytes: number[] = [];
+	let val = value >>> 0; // Ensure unsigned
+	while (val >= 0x80) {
+		bytes.push((val & 0x7f) | 0x80);
+		val >>>= 7;
+	}
+	bytes.push(val & 0x7f);
+	return new Uint8Array(bytes);
+}
+
+/**
+ * Encode a protobuf field (tag + value)
+ */
+export function encodeField(
+	fieldNum: number,
+	wireType: WireType,
+	value: number | string | Uint8Array
+): Uint8Array {
+	const tag = (fieldNum << 3) | wireType;
+	const tagBytes = encodeVarint(tag);
+
+	if (wireType === WIRE_TYPE.VARINT) {
+		const valueBytes = encodeVarint(value as number);
+		return concatArrays(tagBytes, valueBytes);
+	}
+
+	if (wireType === WIRE_TYPE.LEN) {
+		const dataBytes =
+			typeof value === "string"
+				? new TextEncoder().encode(value)
+				: value instanceof Uint8Array
+					? value
+					: new Uint8Array(0);
+
+		const lengthBytes = encodeVarint(dataBytes.length);
+		return concatArrays(tagBytes, lengthBytes, dataBytes);
+	}
+
+	return new Uint8Array(0);
+}
+
+/**
+ * Concatenate multiple Uint8Arrays
+ */
+function concatArrays(...arrays: Uint8Array[]): Uint8Array {
+	const totalLength = arrays.reduce((sum, arr) => sum + arr.length, 0);
+	const result = new Uint8Array(totalLength);
+	let offset = 0;
+	for (const arr of arrays) {
+		result.set(arr, offset);
+		offset += arr.length;
+	}
+	return result;
+}
+
+/**
+ * Encode a tool result
+ */
+export function encodeToolResult(toolResult: CursorToolResult): Uint8Array {
+	const toolCallId = toolResult.tool_call_id || "";
+	const toolName = toolResult.name || "";
+	const toolIndex = toolResult.index || 0;
+	const rawArgs = toolResult.raw_args || "{}";
+
+	return concatArrays(
+		encodeField(FIELD.TOOL_RESULT_CALL_ID, WIRE_TYPE.LEN, toolCallId),
+		encodeField(FIELD.TOOL_RESULT_NAME, WIRE_TYPE.LEN, toolName),
+		encodeField(FIELD.TOOL_RESULT_INDEX, WIRE_TYPE.VARINT, toolIndex),
+		encodeField(FIELD.TOOL_RESULT_RAW_ARGS, WIRE_TYPE.LEN, rawArgs)
+	);
+}
+
+/**
+ * Encode a conversation message
+ */
+export function encodeMessage(
+	content: string,
+	role: RoleType,
+	messageId: string,
+	isLast: boolean,
+	hasTools: boolean,
+	toolResults: CursorToolResult[]
+): Uint8Array {
+	return concatArrays(
+		encodeField(FIELD.MSG_CONTENT, WIRE_TYPE.LEN, content),
+		encodeField(FIELD.MSG_ROLE, WIRE_TYPE.VARINT, role),
+		encodeField(FIELD.MSG_ID, WIRE_TYPE.LEN, messageId),
+		...(toolResults.length > 0
+			? toolResults.map((tr) =>
+					encodeField(
+						FIELD.MSG_TOOL_RESULTS,
+						WIRE_TYPE.LEN,
+						encodeToolResult(tr)
+					)
+				)
+			: []),
+		encodeField(FIELD.MSG_IS_AGENTIC, WIRE_TYPE.VARINT, hasTools ? 1 : 0),
+		encodeField(
+			FIELD.MSG_UNIFIED_MODE,
+			WIRE_TYPE.VARINT,
+			hasTools ? UNIFIED_MODE.AGENT : UNIFIED_MODE.CHAT
+		),
+		...(isLast && hasTools
+			? [
+					encodeField(
+						FIELD.MSG_SUPPORTED_TOOLS,
+						WIRE_TYPE.LEN,
+						encodeVarint(1)
+					),
+				]
+			: [])
+	);
+}
+
+/**
+ * Encode instruction text
+ */
+export function encodeInstruction(text: string): Uint8Array {
+	return text
+		? encodeField(FIELD.INSTRUCTION_TEXT, WIRE_TYPE.LEN, text)
+		: new Uint8Array(0);
+}
+
+/**
+ * Encode model information
+ */
+export function encodeModel(modelName: string): Uint8Array {
+	return concatArrays(
+		encodeField(FIELD.MODEL_NAME, WIRE_TYPE.LEN, modelName),
+		encodeField(FIELD.MODEL_EMPTY, WIRE_TYPE.LEN, new Uint8Array(0))
+	);
+}
+
+/**
+ * Encode cursor settings
+ */
+export function encodeCursorSetting(): Uint8Array {
+	const unknown6 = concatArrays(
+		encodeField(FIELD.SETTING6_FIELD_1, WIRE_TYPE.LEN, new Uint8Array(0)),
+		encodeField(FIELD.SETTING6_FIELD_2, WIRE_TYPE.LEN, new Uint8Array(0))
+	);
+
+	return concatArrays(
+		encodeField(FIELD.SETTING_PATH, WIRE_TYPE.LEN, "cursor\\aisettings"),
+		encodeField(FIELD.SETTING_UNKNOWN_3, WIRE_TYPE.LEN, new Uint8Array(0)),
+		encodeField(FIELD.SETTING_UNKNOWN_6, WIRE_TYPE.LEN, unknown6),
+		encodeField(FIELD.SETTING_UNKNOWN_8, WIRE_TYPE.VARINT, 1),
+		encodeField(FIELD.SETTING_UNKNOWN_9, WIRE_TYPE.VARINT, 1)
+	);
+}
+
+/**
+ * Encode metadata
+ */
+export function encodeMetadata(): Uint8Array {
+	return concatArrays(
+		encodeField(FIELD.META_PLATFORM, WIRE_TYPE.LEN, process.platform || "linux"),
+		encodeField(FIELD.META_ARCH, WIRE_TYPE.LEN, process.arch || "x64"),
+		encodeField(FIELD.META_VERSION, WIRE_TYPE.LEN, process.version || "v20.0.0"),
+		encodeField(FIELD.META_CWD, WIRE_TYPE.LEN, process.cwd() || "/"),
+		encodeField(FIELD.META_TIMESTAMP, WIRE_TYPE.LEN, new Date().toISOString())
+	);
+}
+
+/**
+ * Encode message ID
+ */
+export function encodeMessageId(
+	messageId: string,
+	role: RoleType,
+	summaryId?: string
+): Uint8Array {
+	return concatArrays(
+		encodeField(FIELD.MSGID_ID, WIRE_TYPE.LEN, messageId),
+		...(summaryId
+			? [encodeField(FIELD.MSGID_SUMMARY, WIRE_TYPE.LEN, summaryId)]
+			: []),
+		encodeField(FIELD.MSGID_ROLE, WIRE_TYPE.VARINT, role)
+	);
+}
+
+/**
+ * Encode MCP tool
+ */
+export function encodeMcpTool(tool: CursorTool): Uint8Array {
+	const toolName = tool.function?.name || tool.name || "";
+	const toolDesc = tool.function?.description || tool.description || "";
+	const inputSchema = tool.function?.parameters || tool.input_schema || {};
+
+	return concatArrays(
+		...(toolName
+			? [encodeField(FIELD.MCP_TOOL_NAME, WIRE_TYPE.LEN, toolName)]
+			: []),
+		...(toolDesc
+			? [encodeField(FIELD.MCP_TOOL_DESC, WIRE_TYPE.LEN, toolDesc)]
+			: []),
+		...(Object.keys(inputSchema).length > 0
+			? [
+					encodeField(
+						FIELD.MCP_TOOL_PARAMS,
+						WIRE_TYPE.LEN,
+						JSON.stringify(inputSchema)
+					),
+				]
+			: []),
+		encodeField(FIELD.MCP_TOOL_SERVER, WIRE_TYPE.LEN, "custom")
+	);
+}
+
+/**
+ * Wrap payload in ConnectRPC frame (5-byte header + payload)
+ */
+export function wrapConnectRPCFrame(
+	payload: Uint8Array,
+	compress = false
+): Uint8Array {
+	let finalPayload = payload;
+	let flags: number = COMPRESS_FLAG.NONE;
+
+	if (compress) {
+		finalPayload = new Uint8Array(zlib.gzipSync(Buffer.from(payload)));
+		flags = COMPRESS_FLAG.GZIP;
+	}
+
+	const frame = new Uint8Array(5 + finalPayload.length);
+	frame[0] = flags;
+	frame[1] = (finalPayload.length >> 24) & 0xff;
+	frame[2] = (finalPayload.length >> 16) & 0xff;
+	frame[3] = (finalPayload.length >> 8) & 0xff;
+	frame[4] = finalPayload.length & 0xff;
+	frame.set(finalPayload, 5);
+
+	return frame;
+}
diff --git a/src/cursor/cursor-protobuf-schema.ts b/src/cursor/cursor-protobuf-schema.ts
new file mode 100644
index 00000000..64034e61
--- /dev/null
+++ b/src/cursor/cursor-protobuf-schema.ts
@@ -0,0 +1,205 @@
+/**
+ * Cursor Protobuf Schema Constants
+ * Field definitions and wire types for ConnectRPC protocol
+ */
+
+/** Wire types for protobuf encoding */
+export const WIRE_TYPE = {
+	VARINT: 0,
+	FIXED64: 1,
+	LEN: 2,
+	FIXED32: 5,
+} as const;
+
+/** Message role constants */
+export const ROLE = {
+	USER: 1,
+	ASSISTANT: 2,
+} as const;
+
+/** Unified mode constants */
+export const UNIFIED_MODE = {
+	CHAT: 1,
+	AGENT: 2,
+} as const;
+
+/** Thinking level constants */
+export const THINKING_LEVEL = {
+	UNSPECIFIED: 0,
+	MEDIUM: 1,
+	HIGH: 2,
+} as const;
+
+/** Field numbers for all protobuf messages */
+export const FIELD = {
+	// StreamUnifiedChatRequestWithTools (top level)
+	REQUEST: 1,
+
+	// StreamUnifiedChatRequest
+	MESSAGES: 1,
+	UNKNOWN_2: 2,
+	INSTRUCTION: 3,
+	UNKNOWN_4: 4,
+	MODEL: 5,
+	WEB_TOOL: 8,
+	UNKNOWN_13: 13,
+	CURSOR_SETTING: 15,
+	UNKNOWN_19: 19,
+	CONVERSATION_ID: 23,
+	METADATA: 26,
+	IS_AGENTIC: 27,
+	SUPPORTED_TOOLS: 29,
+	MESSAGE_IDS: 30,
+	MCP_TOOLS: 34,
+	LARGE_CONTEXT: 35,
+	UNKNOWN_38: 38,
+	UNIFIED_MODE: 46,
+	UNKNOWN_47: 47,
+	SHOULD_DISABLE_TOOLS: 48,
+	THINKING_LEVEL: 49,
+	UNKNOWN_51: 51,
+	UNKNOWN_53: 53,
+	UNIFIED_MODE_NAME: 54,
+
+	// ConversationMessage
+	MSG_CONTENT: 1,
+	MSG_ROLE: 2,
+	MSG_ID: 13,
+	MSG_TOOL_RESULTS: 18,
+	MSG_IS_AGENTIC: 29,
+	MSG_UNIFIED_MODE: 47,
+	MSG_SUPPORTED_TOOLS: 51,
+
+	// ConversationMessage.ToolResult
+	TOOL_RESULT_CALL_ID: 1,
+	TOOL_RESULT_NAME: 2,
+	TOOL_RESULT_INDEX: 3,
+	TOOL_RESULT_RAW_ARGS: 5,
+	TOOL_RESULT_RESULT: 8,
+
+	// Model
+	MODEL_NAME: 1,
+	MODEL_EMPTY: 4,
+
+	// Instruction
+	INSTRUCTION_TEXT: 1,
+
+	// CursorSetting
+	SETTING_PATH: 1,
+	SETTING_UNKNOWN_3: 3,
+	SETTING_UNKNOWN_6: 6,
+	SETTING_UNKNOWN_8: 8,
+	SETTING_UNKNOWN_9: 9,
+
+	// CursorSetting.Unknown6
+	SETTING6_FIELD_1: 1,
+	SETTING6_FIELD_2: 2,
+
+	// Metadata
+	META_PLATFORM: 1,
+	META_ARCH: 2,
+	META_VERSION: 3,
+	META_CWD: 4,
+	META_TIMESTAMP: 5,
+
+	// MessageId
+	MSGID_ID: 1,
+	MSGID_SUMMARY: 2,
+	MSGID_ROLE: 3,
+
+	// MCPTool
+	MCP_TOOL_NAME: 1,
+	MCP_TOOL_DESC: 2,
+	MCP_TOOL_PARAMS: 3,
+	MCP_TOOL_SERVER: 4,
+
+	// StreamUnifiedChatResponseWithTools (response)
+	TOOL_CALL: 1,
+	RESPONSE: 2,
+
+	// ClientSideToolV2Call
+	TOOL_ID: 3,
+	TOOL_NAME: 9,
+	TOOL_RAW_ARGS: 10,
+	TOOL_IS_LAST: 11,
+	TOOL_MCP_PARAMS: 27,
+
+	// MCPParams
+	MCP_TOOLS_LIST: 1,
+
+	// MCPParams.Tool (nested)
+	MCP_NESTED_NAME: 1,
+	MCP_NESTED_PARAMS: 3,
+
+	// StreamUnifiedChatResponse
+	RESPONSE_TEXT: 1,
+	THINKING: 25,
+
+	// Thinking
+	THINKING_TEXT: 1,
+} as const;
+
+/** Type definitions */
+export type WireType = (typeof WIRE_TYPE)[keyof typeof WIRE_TYPE];
+export type RoleType = (typeof ROLE)[keyof typeof ROLE];
+export type UnifiedModeType = (typeof UNIFIED_MODE)[keyof typeof UNIFIED_MODE];
+export type ThinkingLevelType =
+	(typeof THINKING_LEVEL)[keyof typeof THINKING_LEVEL];
+export type FieldNumber = (typeof FIELD)[keyof typeof FIELD];
+
+/** Cursor tool definition */
+export interface CursorTool {
+	function?: {
+		name?: string;
+		description?: string;
+		parameters?: Record<string, unknown>;
+	};
+	name?: string;
+	description?: string;
+	input_schema?: Record<string, unknown>;
+}
+
+/** Cursor tool result */
+export interface CursorToolResult {
+	tool_call_id?: string;
+	name?: string;
+	index?: number;
+	raw_args?: string;
+}
+
+/** Cursor message format */
+export interface CursorMessage {
+	role: string;
+	content: string;
+	tool_results?: CursorToolResult[];
+	tool_calls?: Array<{
+		id: string;
+		type: string;
+		function: {
+			name: string;
+			arguments: string;
+		};
+	}>;
+}
+
+/** Formatted message for encoding */
+export interface FormattedMessage {
+	content: string;
+	role: RoleType;
+	messageId: string;
+	isLast: boolean;
+	hasTools: boolean;
+	toolResults: CursorToolResult[];
+}
+
+/** Message ID structure */
+export interface MessageId {
+	messageId: string;
+	role: RoleType;
+}
+
+/** Compression flags for ConnectRPC frames */
+export const COMPRESS_FLAG = {
+	NONE: 0x00,
+	GZIP: 0x01,
+} as const;
diff --git a/src/cursor/cursor-protobuf.ts b/src/cursor/cursor-protobuf.ts
new file mode 100644
index 00000000..60e4d588
--- /dev/null
+++ b/src/cursor/cursor-protobuf.ts
@@ -0,0 +1,212 @@
+/**
+ * Cursor Protobuf Main Module
+ * Exports encoder/decoder functions and builds complete requests
+ */
+
+import { randomUUID } from "crypto";
+import {
+	ROLE,
+	UNIFIED_MODE,
+	THINKING_LEVEL,
+	FIELD,
+	type CursorMessage,
+	type CursorTool,
+	type FormattedMessage,
+	type MessageId,
+	type ThinkingLevelType,
+} from "./cursor-protobuf-schema.js";
+import {
+	encodeField,
+	encodeVarint,
+	encodeMessage,
+	encodeInstruction,
+	encodeModel,
+	encodeCursorSetting,
+	encodeMetadata,
+	encodeMessageId,
+	encodeMcpTool,
+	wrapConnectRPCFrame,
+} from "./cursor-protobuf-encoder.js";
+import {
+	decodeVarint,
+	decodeField,
+	decodeMessage,
+	parseConnectRPCFrame,
+	extractTextFromResponse,
+} from "./cursor-protobuf-decoder.js";
+import { WIRE_TYPE } from "./cursor-protobuf-schema.js";
+
+/**
+ * Build complete chat request protobuf
+ */
+export function encodeRequest(
+	messages: CursorMessage[],
+	modelName: string,
+	tools: CursorTool[] = [],
+	reasoningEffort: string | null = null
+): Uint8Array {
+	const hasTools = tools?.length > 0;
+	const isAgentic = hasTools;
+	const formattedMessages: FormattedMessage[] = [];
+	const messageIds: MessageId[] = [];
+
+	// Prepare messages
+	for (let i = 0; i < messages.length; i++) {
+		const msg = messages[i];
+		const role = msg.role === "user" ? ROLE.USER : ROLE.ASSISTANT;
+		const msgId = randomUUID();
+		const isLast = i === messages.length - 1;
+
+		formattedMessages.push({
+			content: msg.content,
+			role,
+			messageId: msgId,
+			isLast,
+			hasTools,
+			toolResults: msg.tool_results || [],
+		});
+
+		messageIds.push({ messageId: msgId, role });
+	}
+
+	// Map reasoning effort to thinking level
+	let thinkingLevel: ThinkingLevelType = THINKING_LEVEL.UNSPECIFIED;
+	if (reasoningEffort === "medium") thinkingLevel = THINKING_LEVEL.MEDIUM;
+	else if (reasoningEffort === "high") thinkingLevel = THINKING_LEVEL.HIGH;
+
+	// Build arrays for messages and tools
+	const messageFields = formattedMessages.map((fm) =>
+		encodeField(
+			FIELD.MESSAGES,
+			WIRE_TYPE.LEN,
+			encodeMessage(
+				fm.content,
+				fm.role,
+				fm.messageId,
+				fm.isLast,
+				fm.hasTools,
+				fm.toolResults
+			)
+		)
+	);
+
+	const messageIdFields = messageIds.map((mid) =>
+		encodeField(
+			FIELD.MESSAGE_IDS,
+			WIRE_TYPE.LEN,
+			encodeMessageId(mid.messageId, mid.role)
+		)
+	);
+
+	const toolFields =
+		tools?.length > 0
+			? tools.map((tool) =>
+					encodeField(FIELD.MCP_TOOLS, WIRE_TYPE.LEN, encodeMcpTool(tool))
+				)
+			: [];
+
+	const supportedToolsField = isAgentic
+		? [encodeField(FIELD.SUPPORTED_TOOLS, WIRE_TYPE.LEN, encodeVarint(1))]
+		: [];
+
+	// Concatenate all parts
+	const parts: Uint8Array[] = [
+		...messageFields,
+		encodeField(FIELD.UNKNOWN_2, WIRE_TYPE.VARINT, 1),
+		encodeField(FIELD.INSTRUCTION, WIRE_TYPE.LEN, encodeInstruction("")),
+		encodeField(FIELD.UNKNOWN_4, WIRE_TYPE.VARINT, 1),
+		encodeField(FIELD.MODEL, WIRE_TYPE.LEN, encodeModel(modelName)),
+		encodeField(FIELD.WEB_TOOL, WIRE_TYPE.LEN, ""),
+		encodeField(FIELD.UNKNOWN_13, WIRE_TYPE.VARINT, 1),
+		encodeField(FIELD.CURSOR_SETTING, WIRE_TYPE.LEN, encodeCursorSetting()),
+		encodeField(FIELD.UNKNOWN_19, WIRE_TYPE.VARINT, 1),
+		encodeField(FIELD.CONVERSATION_ID, WIRE_TYPE.LEN, randomUUID()),
+		encodeField(FIELD.METADATA, WIRE_TYPE.LEN, encodeMetadata()),
+		encodeField(FIELD.IS_AGENTIC, WIRE_TYPE.VARINT, isAgentic ? 1 : 0),
+		...supportedToolsField,
+		...messageIdFields,
+		...toolFields,
+		encodeField(FIELD.LARGE_CONTEXT, WIRE_TYPE.VARINT, 0),
+		encodeField(FIELD.UNKNOWN_38, WIRE_TYPE.VARINT, 0),
+		encodeField(
+			FIELD.UNIFIED_MODE,
+			WIRE_TYPE.VARINT,
+			isAgentic ? UNIFIED_MODE.AGENT : UNIFIED_MODE.CHAT
+		),
+		encodeField(FIELD.UNKNOWN_47, WIRE_TYPE.LEN, ""),
+		encodeField(FIELD.SHOULD_DISABLE_TOOLS, WIRE_TYPE.VARINT, isAgentic ? 0 : 1),
+		encodeField(FIELD.THINKING_LEVEL, WIRE_TYPE.VARINT, thinkingLevel),
+		encodeField(FIELD.UNKNOWN_51, WIRE_TYPE.VARINT, 0),
+		encodeField(FIELD.UNKNOWN_53, WIRE_TYPE.VARINT, 1),
+		encodeField(
+			FIELD.UNIFIED_MODE_NAME,
+			WIRE_TYPE.LEN,
+			isAgentic ? "Agent" : "Ask"
+		),
+	];
+
+	return concatArrays(...parts);
+}
+
+/**
+ * Build chat request wrapped in top-level message
+ */
+export function buildChatRequest(
+	messages: CursorMessage[],
+	modelName: string,
+	tools: CursorTool[] = [],
+	reasoningEffort: string | null = null
+): Uint8Array {
+	return encodeField(
+		FIELD.REQUEST,
+		WIRE_TYPE.LEN,
+		encodeRequest(messages, modelName, tools, reasoningEffort)
+	);
+}
+
+/**
+ * Generate complete Cursor request body with ConnectRPC framing
+ */
+export function generateCursorBody(
+	messages: CursorMessage[],
+	modelName: string,
+	tools: CursorTool[] = [],
+	reasoningEffort: string | null = null
+): Uint8Array {
+	const protobuf = buildChatRequest(messages, modelName, tools, reasoningEffort);
+	const framed = wrapConnectRPCFrame(protobuf, false); // Cursor doesn't support compressed requests
+	return framed;
+}
+
+/**
+ * Concatenate multiple Uint8Arrays
+ */
+function concatArrays(...arrays: Uint8Array[]): Uint8Array {
+	const totalLength = arrays.reduce((sum, arr) => sum + arr.length, 0);
+	const result = new Uint8Array(totalLength);
+	let offset = 0;
+	for (const arr of arrays) {
+		result.set(arr, offset);
+		offset += arr.length;
+	}
+	return result;
+}
+
+// Re-export all functions
+export {
+	encodeVarint,
+	encodeField,
+	encodeMessage,
+	encodeInstruction,
+	encodeModel,
+	encodeCursorSetting,
+	encodeMetadata,
+	encodeMessageId,
+	encodeMcpTool,
+	wrapConnectRPCFrame,
+	decodeVarint,
+	decodeField,
+	decodeMessage,
+	parseConnectRPCFrame,
+	extractTextFromResponse,
+};
diff --git a/src/cursor/cursor-translator.ts b/src/cursor/cursor-translator.ts
new file mode 100644
index 00000000..e40d4d5d
--- /dev/null
+++ b/src/cursor/cursor-translator.ts
@@ -0,0 +1,145 @@
+/**
+ * OpenAI to Cursor Request Translator
+ * Converts OpenAI messages to Cursor format
+ */
+
+import type {
+	CursorMessage,
+	CursorToolResult,
+	CursorTool,
+} from "./cursor-protobuf-schema.js";
+
+/** OpenAI message format */
+interface OpenAIMessage {
+	role: string;
+	content: string | Array<{ type: string; text?: string }>;
+	name?: string;
+	tool_call_id?: string;
+	tool_calls?: Array<{
+		id: string;
+		type: string;
+		function: { name: string; arguments: string };
+	}>;
+}
+
+/** OpenAI request body */
+interface OpenAIRequestBody {
+	messages: OpenAIMessage[];
+	tools?: CursorTool[];
+	reasoning_effort?: string;
+}
+
+/**
+ * Convert OpenAI messages to Cursor format with native tool_results support
+ * - system → user with [System Instructions] prefix
+ * - tool → accumulate into tool_results array for next user/assistant message
+ * - assistant with tool_calls → keep tool_calls structure (Cursor supports it natively)
+ */
+function convertMessages(messages: OpenAIMessage[]): CursorMessage[] {
+	const result: CursorMessage[] = [];
+	let pendingToolResults: CursorToolResult[] = [];
+
+	for (let i = 0; i < messages.length; i++) {
+		const msg = messages[i];
+
+		if (msg.role === "system") {
+			result.push({
+				role: "user",
+				content: `[System Instructions]\n${msg.content}`,
+			});
+			continue;
+		}
+
+		if (msg.role === "tool") {
+			let toolContent = "";
+			if (typeof msg.content === "string") {
+				toolContent = msg.content;
+			} else if (Array.isArray(msg.content)) {
+				for (const part of msg.content) {
+					if (part.type === "text" && part.text) {
+						toolContent += part.text;
+					}
+				}
+			}
+
+			const toolName = msg.name || "tool";
+			const toolCallId = msg.tool_call_id || "";
+
+			// Accumulate tool result
+			pendingToolResults.push({
+				tool_call_id: toolCallId,
+				name: toolName,
+				index: pendingToolResults.length,
+				raw_args: toolContent,
+			});
+			continue;
+		}
+
+		if (msg.role === "user" || msg.role === "assistant") {
+			let content = "";
+
+			if (typeof msg.content === "string") {
+				content = msg.content;
+			} else if (Array.isArray(msg.content)) {
+				for (const part of msg.content) {
+					if (part.type === "text" && part.text) {
+						content += part.text;
+					}
+				}
+			}
+
+			// Keep tool_calls structure for assistant messages
+			if (msg.role === "assistant" && msg.tool_calls && msg.tool_calls.length > 0) {
+				const assistantMsg: CursorMessage = { role: "assistant", content: "" };
+				if (content) {
+					assistantMsg.content = content;
+				}
+				assistantMsg.tool_calls = msg.tool_calls;
+
+				// Attach pending tool results to assistant message with tool_calls
+				if (pendingToolResults.length > 0) {
+					assistantMsg.tool_results = pendingToolResults;
+					pendingToolResults = [];
+				}
+
+				result.push(assistantMsg);
+			} else if (content || pendingToolResults.length > 0) {
+				const msgObj: CursorMessage = {
+					role: msg.role,
+					content: content || "",
+				};
+
+				// Attach pending tool results to this message
+				if (pendingToolResults.length > 0) {
+					msgObj.tool_results = pendingToolResults;
+					pendingToolResults = [];
+				}
+
+				result.push(msgObj);
+			}
+		}
+	}
+
+	return result;
+}
+
+/**
+ * Transform OpenAI request to Cursor format
+ * Returns modified body with converted messages
+ */
+export function buildCursorRequest(
+	model: string,
+	body: OpenAIRequestBody,
+	stream: boolean,
+	credentials: unknown
+): {
+	messages: CursorMessage[];
+	tools?: CursorTool[];
+} {
+	const messages = convertMessages(body.messages || []);
+
+	return {
+		...body,
+		messages,
+	};
+}