Files
9router/open-sse/utils/cursorProtobuf.js
2026-03-11 11:59:07 +07:00

887 lines
28 KiB
JavaScript

/**
* Cursor Protobuf Encoder/Decoder
* Implements ConnectRPC protobuf wire format for Cursor API
*/
import { v4 as uuidv4 } from "uuid";
import zlib from "zlib";
const DEBUG = process.env.CURSOR_PROTOBUF_DEBUG === "1";
const log = (tag, ...args) => DEBUG && console.log(`[PROTOBUF:${tag}]`, ...args);
const textDecoder = new TextDecoder();
const PROTOBUF_SCHEMA_VERSION = "1.1.3";
// ==================== SCHEMAS ====================
const WIRE_TYPE = { VARINT: 0, FIXED64: 1, LEN: 2, FIXED32: 5 };
const ROLE = { USER: 1, ASSISTANT: 2 };
const UNIFIED_MODE = { CHAT: 1, AGENT: 2 };
const THINKING_LEVEL = { UNSPECIFIED: 0, MEDIUM: 1, HIGH: 2 };
const CLIENT_SIDE_TOOL_V2 = { MCP: 19 };
const CLIENT_SIDE_TOOL_V2_MCP = 19;
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,
TOOL_RESULT_TOOL_CALL: 11,
TOOL_RESULT_MODEL_CALL_ID: 12,
// ClientSideToolV2Result (nested inside ToolResult.result)
CLIENT_RESULT_TOOL: 1,
CLIENT_RESULT_MCP_RESULT: 28,
CLIENT_RESULT_TOOL_CALL_ID: 35,
CLIENT_RESULT_MODEL_CALL_ID: 48,
CLIENT_RESULT_TOOL_INDEX: 49,
// MCPResult (nested inside ClientSideToolV2Result.mcp_result)
MCP_RESULT_SELECTED_TOOL: 1,
MCP_RESULT_RESULT: 2,
// ClientSideToolV2Call (nested inside ToolResult.tool_call)
CLIENT_CALL_TOOL: 1,
CLIENT_CALL_MCP_PARAMS: 27,
CLIENT_CALL_TOOL_CALL_ID: 3,
CLIENT_CALL_NAME: 9,
CLIENT_CALL_RAW_ARGS: 10,
CLIENT_CALL_TOOL_INDEX: 48,
CLIENT_CALL_MODEL_CALL_ID: 49,
// 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_IS_LAST_ALT: 15,
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
};
// Known response field numbers — used to detect unknown fields from protocol updates
const KNOWN_RESPONSE_FIELDS = new Set([
FIELD.TOOL_CALL,
FIELD.RESPONSE,
FIELD.TOOL_ID,
FIELD.TOOL_NAME,
FIELD.TOOL_RAW_ARGS,
FIELD.TOOL_IS_LAST,
FIELD.TOOL_MCP_PARAMS,
FIELD.RESPONSE_TEXT,
FIELD.THINKING
]);
// ==================== PRIMITIVE ENCODING ====================
export function encodeVarint(value) {
const bytes = [];
while (value >= 0x80) {
bytes.push((value & 0x7F) | 0x80);
value >>>= 7;
}
bytes.push(value & 0x7F);
return new Uint8Array(bytes);
}
export function encodeField(fieldNum, wireType, value) {
const tag = (fieldNum << 3) | wireType;
const tagBytes = encodeVarint(tag);
if (wireType === WIRE_TYPE.VARINT) {
const valueBytes = encodeVarint(value);
return concatArrays(tagBytes, valueBytes);
}
if (wireType === WIRE_TYPE.LEN) {
const dataBytes = typeof value === "string"
? new TextEncoder().encode(value)
: value instanceof Uint8Array ? value
: Buffer.isBuffer(value) ? new Uint8Array(value)
: new Uint8Array(0);
const lengthBytes = encodeVarint(dataBytes.length);
return concatArrays(tagBytes, lengthBytes, dataBytes);
}
return new Uint8Array(0);
}
function concatArrays(...arrays) {
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;
}
// ==================== MESSAGE ENCODING ====================
/**
* Format tool name: "toolName" → "mcp_custom_toolName"
* Also handles: "mcp__server__tool" → "mcp_server_tool"
*/
function formatToolName(name) {
const base = typeof name === "string" && name.length > 0 ? name : "tool";
if (base.startsWith("mcp__")) {
const rest = base.slice("mcp__".length);
const splitIdx = rest.indexOf("__");
if (splitIdx >= 0) {
const server = rest.slice(0, splitIdx) || "custom";
const toolName = rest.slice(splitIdx + 2) || "tool";
return `mcp_${server}_${toolName}`;
}
return `mcp_custom_${rest || "tool"}`;
}
if (base.startsWith("mcp_")) return base;
return `mcp_custom_${base}`;
}
/**
* Parse formatted tool name: "mcp_server_tool" → { serverName, selectedTool }
*/
function parseToolName(formattedName) {
if (typeof formattedName !== "string" || !formattedName.startsWith("mcp_")) {
return { serverName: "custom", selectedTool: formattedName || "tool" };
}
const tail = formattedName.slice("mcp_".length);
const splitIdx = tail.indexOf("_");
if (splitIdx < 0) {
return { serverName: "custom", selectedTool: tail || "tool" };
}
return {
serverName: tail.slice(0, splitIdx) || "custom",
selectedTool: tail.slice(splitIdx + 1) || "tool"
};
}
/**
* Parse tool_call_id into { toolCallId, modelCallId }
* Cursor uses "\nmc_" delimiter for model_call_id
*/
function parseToolId(id) {
const delimiter = "\nmc_";
const idx = id.indexOf(delimiter);
if (idx >= 0) {
return { toolCallId: id.slice(0, idx), modelCallId: id.slice(idx + delimiter.length) };
}
return { toolCallId: id, modelCallId: null };
}
/**
* Encode MCPResult proto: { selected_tool, result }
*/
function encodeMcpResult(selectedTool, resultContent) {
return concatArrays(
encodeField(FIELD.MCPR_SELECTED_TOOL, WIRE_TYPE.LEN, selectedTool),
encodeField(FIELD.MCPR_RESULT, WIRE_TYPE.LEN, resultContent)
);
}
/**
* Encode ClientSideToolV2Result proto: { tool, mcp_result, call_id, model_call_id, tool_index }
* Represents the result of executing a tool
*/
function encodeClientSideToolV2Result(toolCallId, modelCallId, selectedTool, resultContent, toolIndex = 1) {
return concatArrays(
encodeField(FIELD.CV2R_TOOL, WIRE_TYPE.VARINT, CLIENT_SIDE_TOOL_V2_MCP),
encodeField(FIELD.CV2R_MCP_RESULT, WIRE_TYPE.LEN, encodeMcpResult(selectedTool, resultContent)),
encodeField(FIELD.CV2R_CALL_ID, WIRE_TYPE.LEN, toolCallId),
...(modelCallId ? [encodeField(FIELD.CV2R_MODEL_CALL_ID, WIRE_TYPE.LEN, modelCallId)] : []),
encodeField(FIELD.CV2R_TOOL_INDEX, WIRE_TYPE.VARINT, toolIndex > 0 ? toolIndex : 1)
);
}
/**
* Encode MCPParams.Tool nested inside ClientSideToolV2Call
*/
function encodeMcpParamsForCall(toolName, rawArgs, serverName) {
const tool = concatArrays(
encodeField(FIELD.MCP_TOOL_NAME, WIRE_TYPE.LEN, toolName),
encodeField(FIELD.MCP_TOOL_PARAMS, WIRE_TYPE.LEN, rawArgs),
encodeField(FIELD.MCP_TOOL_SERVER, WIRE_TYPE.LEN, serverName)
);
return encodeField(FIELD.MCP_TOOLS_LIST, WIRE_TYPE.LEN, tool);
}
/**
* Encode ClientSideToolV2Call proto: { tool, mcp_params, call_id, name, raw_args, tool_index, model_call_id }
* Represents a tool call definition
*/
function encodeClientSideToolV2Call(toolCallId, toolName, selectedTool, serverName, rawArgs, modelCallId, toolIndex = 1) {
return concatArrays(
encodeField(FIELD.CV2C_TOOL, WIRE_TYPE.VARINT, CLIENT_SIDE_TOOL_V2_MCP),
encodeField(FIELD.CV2C_MCP_PARAMS, WIRE_TYPE.LEN, encodeMcpParamsForCall(selectedTool, rawArgs, serverName)),
encodeField(FIELD.CV2C_CALL_ID, WIRE_TYPE.LEN, toolCallId),
encodeField(FIELD.CV2C_NAME, WIRE_TYPE.LEN, toolName),
encodeField(FIELD.CV2C_RAW_ARGS, WIRE_TYPE.LEN, rawArgs),
encodeField(FIELD.CV2C_TOOL_INDEX, WIRE_TYPE.VARINT, toolIndex > 0 ? toolIndex : 1),
...(modelCallId ? [encodeField(FIELD.CV2C_MODEL_CALL_ID, WIRE_TYPE.LEN, modelCallId)] : [])
);
}
/**
* Encode ConversationMessage.ToolResult with full structure
* Matches Cursor proto: tool_call_id, tool_name, tool_index, raw_args, result, tool_call
*/
export function encodeToolResult(toolResult) {
const originalName = toolResult.tool_name || toolResult.name || "";
const toolName = formatToolName(originalName);
const rawArgs = toolResult.raw_args || "{}";
const resultContent = toolResult.result_content || toolResult.result || "";
const { toolCallId, modelCallId } = parseToolId(toolResult.tool_call_id || "");
const toolIndex = toolResult.tool_index || toolResult.index || 1;
// Parse tool name to extract server and selected tool
const { serverName, selectedTool } = parseToolName(toolName);
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 > 0 ? toolIndex : 1),
...(modelCallId ? [encodeField(FIELD.TOOL_RESULT_MODEL_CALL_ID, WIRE_TYPE.LEN, modelCallId)] : []),
encodeField(FIELD.TOOL_RESULT_RAW_ARGS, WIRE_TYPE.LEN, rawArgs),
encodeField(FIELD.TOOL_RESULT_RESULT, WIRE_TYPE.LEN,
encodeClientSideToolV2Result(toolCallId, modelCallId, selectedTool, resultContent, toolIndex)
),
encodeField(FIELD.TOOL_RESULT_TOOL_CALL, WIRE_TYPE.LEN,
encodeClientSideToolV2Call(toolCallId, toolName, selectedTool, serverName, rawArgs, modelCallId, toolIndex)
)
);
}
export function encodeMessage(content, role, messageId, chatModeEnum = null, isLast = false, hasTools = false, toolResults = [], serverBubbleId = null) {
const hasToolResults = toolResults.length > 0;
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),
// Only include server_bubble_id if explicitly provided (last assistant message only)
...(serverBubbleId ? [encodeField(FIELD.MSG_SERVER_BUBBLE_ID, WIRE_TYPE.LEN, serverBubbleId)] : []),
...(hasToolResults ? 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))] : [])
);
}
export function encodeInstruction(text) {
return text ? encodeField(FIELD.INSTRUCTION_TEXT, WIRE_TYPE.LEN, text) : new Uint8Array(0);
}
export function encodeModel(modelName) {
return concatArrays(
encodeField(FIELD.MODEL_NAME, WIRE_TYPE.LEN, modelName),
encodeField(FIELD.MODEL_EMPTY, WIRE_TYPE.LEN, new Uint8Array(0))
);
}
export function encodeCursorSetting() {
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)
);
}
export function encodeMetadata() {
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())
);
}
export function encodeMessageId(messageId, role, summaryId = null) {
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)
);
}
export function encodeMcpTool(tool) {
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")
);
}
// ==================== REQUEST BUILDING ====================
export function encodeRequest(messages, modelName, tools = [], reasoningEffort = null) {
const hasTools = tools?.length > 0;
const isAgentic = hasTools;
const formattedMessages = [];
const messageIds = [];
const normalizedMessages = [];
// Guardrail: split mixed assistant payload into separate assistant messages
// This prevents protobuf encoding errors when tool calls and results are in same message
for (let i = 0; i < messages.length; i++) {
const msg = messages[i];
const hasToolCalls = Array.isArray(msg?.tool_calls) && msg.tool_calls.length > 0;
const hasToolResults = Array.isArray(msg?.tool_results) && msg.tool_results.length > 0;
if (msg?.role === "assistant" && hasToolCalls && hasToolResults) {
log(
"ENCODE",
`normalizing mixed assistant tool payload at msg[${i}] (calls=${msg.tool_calls.length}, results=${msg.tool_results.length})`
);
// Keep assistant tool call message without embedded results
normalizedMessages.push({
...msg,
tool_results: []
});
// Avoid inserting duplicate assistant tool-result message if next one already matches
const nextMsg = messages[i + 1];
const nextHasToolResults =
nextMsg?.role === "assistant" &&
Array.isArray(nextMsg?.tool_results) &&
nextMsg.tool_results.length > 0;
const currentIds = new Set(
msg.tool_results.map(tr => tr?.tool_call_id).filter(id => typeof id === "string")
);
const nextIds = new Set(
(nextMsg?.tool_results || [])
.map(tr => tr?.tool_call_id)
.filter(id => typeof id === "string")
);
let sameIds = currentIds.size > 0 && currentIds.size === nextIds.size;
if (sameIds) {
for (const id of currentIds) {
if (!nextIds.has(id)) {
sameIds = false;
break;
}
}
}
if (!(nextHasToolResults && sameIds)) {
normalizedMessages.push({
role: "assistant",
content: "",
tool_results: msg.tool_results
});
}
continue;
}
normalizedMessages.push(msg);
}
// Prepare messages
for (let i = 0; i < normalizedMessages.length; i++) {
const msg = normalizedMessages[i];
const role = msg.role === "user" ? ROLE.USER : ROLE.ASSISTANT;
const msgId = uuidv4();
const isLast = i === normalizedMessages.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 = THINKING_LEVEL.UNSPECIFIED;
if (reasoningEffort === "medium") thinkingLevel = THINKING_LEVEL.MEDIUM;
else if (reasoningEffort === "high") thinkingLevel = THINKING_LEVEL.HIGH;
// Build request
return concatArrays(
// Messages
...formattedMessages.map(fm =>
encodeField(FIELD.MESSAGES, WIRE_TYPE.LEN,
encodeMessage(fm.content, fm.role, fm.messageId, null, fm.isLast, fm.hasTools, fm.toolResults)
)
),
// Static fields
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, uuidv4()),
encodeField(FIELD.METADATA, WIRE_TYPE.LEN, encodeMetadata()),
// Tool-related fields
encodeField(FIELD.IS_AGENTIC, WIRE_TYPE.VARINT, isAgentic ? 1 : 0),
...(isAgentic ? [encodeField(FIELD.SUPPORTED_TOOLS, WIRE_TYPE.LEN, encodeVarint(1))] : []),
// Message IDs
...messageIds.map(mid =>
encodeField(FIELD.MESSAGE_IDS, WIRE_TYPE.LEN, encodeMessageId(mid.messageId, mid.role))
),
// MCP Tools
...(tools?.length > 0 ? tools.map(tool =>
encodeField(FIELD.MCP_TOOLS, WIRE_TYPE.LEN, encodeMcpTool(tool))
) : []),
// Mode fields
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")
);
}
export function buildChatRequest(messages, modelName, tools = [], reasoningEffort = null) {
return encodeField(FIELD.REQUEST, WIRE_TYPE.LEN, encodeRequest(messages, modelName, tools, reasoningEffort));
}
/**
* Encode a tool result as ClientSideToolV2Result (field 2 of StreamUnifiedChatRequestWithTools)
* This is sent as a SEPARATE request frame, not inside conversation messages.
* Proto: StreamUnifiedChatRequestWithTools.client_side_tool_v2_result = 2
*/
export function buildToolResultRequest(toolResult) {
const { toolCallId, modelCallId } = parseToolId(toolResult.tool_call_id || "");
const rawName = toolResult.tool_name || "";
const resultContent = toolResult.result_content || "";
// selected_tool = raw tool name (e.g. "Write", "Read") per cursor-api Rust source:
// McpResult { selected_tool: tool_name, result } where tool_name is the mcpParams.tools[0].name
// which is the name AFTER server prefix stripping (e.g. "custom_Write" -> name = "Write")
// Actually cursor-api uses: name = tool_name.slice_unchecked(d+1..) → raw name without "custom_"
// So selected_tool = raw tool name without any prefix
const selectedTool = rawName.startsWith("mcp_custom_")
? rawName.slice("mcp_custom_".length)
: rawName.startsWith("mcp_")
? rawName.slice(4)
: rawName;
// ClientSideToolV2Result per proto:
// field 1 (tool): varint = 19 (MCP)
// field 28 (mcp_result): LEN { field 1: selected_tool, field 2: result }
// field 35 (tool_call_id): string
// field 48 (model_call_id): string (optional)
// NO tool_index (None in Rust source: encode_tool_result sets tool_index: None)
const cv2Result = concatArrays(
encodeField(FIELD.CV2R_TOOL, WIRE_TYPE.VARINT, CLIENT_SIDE_TOOL_V2_MCP),
encodeField(FIELD.CV2R_MCP_RESULT, WIRE_TYPE.LEN, encodeMcpResult(selectedTool, resultContent)),
encodeField(FIELD.CV2R_CALL_ID, WIRE_TYPE.LEN, toolCallId),
...(modelCallId ? [encodeField(FIELD.CV2R_MODEL_CALL_ID, WIRE_TYPE.LEN, modelCallId)] : [])
// tool_index intentionally omitted (None per Rust source)
);
// StreamUnifiedChatRequestWithTools: field 2 = client_side_tool_v2_result
return encodeField(2, WIRE_TYPE.LEN, cv2Result);
}
export function wrapConnectRPCFrame(payload, compress = false) {
let finalPayload = payload;
let flags = 0x00;
if (compress) {
finalPayload = new Uint8Array(zlib.gzipSync(Buffer.from(payload)));
flags = 0x01;
}
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;
}
export function generateCursorBody(messages, modelName, tools = [], reasoningEffort = null) {
log("BODY", `Generating: ${messages.length} msgs, model=${modelName}, tools=${tools.length}, reasoning=${reasoningEffort || "none"}`);
const protobuf = buildChatRequest(messages, modelName, tools, reasoningEffort);
const framed = wrapConnectRPCFrame(protobuf, false); // Cursor doesn't support compressed requests
log("BODY", `Protobuf=${protobuf.length}B, Framed=${framed.length}B`);
return framed;
}
/**
* Generate a framed tool result body to send as a separate request frame.
* Uses field 2 (client_side_tool_v2_result) of StreamUnifiedChatRequestWithTools.
*/
export function generateToolResultBody(toolResult) {
const protobuf = buildToolResultRequest(toolResult);
return wrapConnectRPCFrame(protobuf, false);
}
// ==================== PRIMITIVE DECODING ====================
export function decodeVarint(buffer, offset) {
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];
}
export function decodeField(buffer, offset) {
if (offset >= buffer.length) return [null, null, null, offset];
const [tag, pos1] = decodeVarint(buffer, offset);
const fieldNum = tag >> 3;
const wireType = tag & 0x07;
let value;
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];
}
export function decodeMessage(data) {
const fields = new Map();
let pos = 0;
while (pos < data.length) {
const [fieldNum, wireType, value, newPos] = decodeField(data, pos);
if (fieldNum === null) break;
if (!fields.has(fieldNum)) fields.set(fieldNum, []);
fields.get(fieldNum).push({ wireType, value });
pos = newPos;
}
return fields;
}
// ==================== RESPONSE PARSING ====================
export function parseConnectRPCFrame(buffer) {
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) {
try {
payload = new Uint8Array(zlib.gunzipSync(Buffer.from(payload)));
} catch (err) {
log("PARSE", `Decompression failed: ${err.message}`);
}
}
return { flags, length, payload, consumed: 5 + length };
}
function extractToolCall(toolCallData) {
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);
toolCallId = fullId.split("\n")[0]; // Cursor returns multi-line ID, take first line
}
// Extract tool name
if (toolCall.has(FIELD.TOOL_NAME)) {
toolName = new TextDecoder().decode(toolCall.get(FIELD.TOOL_NAME)[0].value);
}
// Extract is_last flag
if (toolCall.has(FIELD.TOOL_IS_LAST)) {
isLast = toolCall.get(FIELD.TOOL_IS_LAST)[0].value !== 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);
if (mcpParams.has(FIELD.MCP_TOOLS_LIST)) {
const tool = decodeMessage(mcpParams.get(FIELD.MCP_TOOLS_LIST)[0].value);
if (tool.has(FIELD.MCP_NESTED_NAME)) {
toolName = new TextDecoder().decode(tool.get(FIELD.MCP_NESTED_NAME)[0].value);
}
if (tool.has(FIELD.MCP_NESTED_PARAMS)) {
rawArgs = new TextDecoder().decode(tool.get(FIELD.MCP_NESTED_PARAMS)[0].value);
}
}
} catch (err) {
log("EXTRACT", `MCP parse error: ${err.message}`);
}
}
// Fallback to raw_args
if (!rawArgs && toolCall.has(FIELD.TOOL_RAW_ARGS)) {
rawArgs = new TextDecoder().decode(toolCall.get(FIELD.TOOL_RAW_ARGS)[0].value);
}
if (toolCallId && toolName) {
return {
id: toolCallId,
type: "function",
function: {
name: toolName,
arguments: rawArgs || "{}"
},
isLast
};
}
return null;
}
function extractTextAndThinking(responseData) {
const nested = decodeMessage(responseData);
let text = null;
let thinking = null;
// Extract text
if (nested.has(FIELD.RESPONSE_TEXT)) {
text = new TextDecoder().decode(nested.get(FIELD.RESPONSE_TEXT)[0].value);
}
// Extract thinking
if (nested.has(FIELD.THINKING)) {
try {
const thinkingMsg = decodeMessage(nested.get(FIELD.THINKING)[0].value);
if (thinkingMsg.has(FIELD.THINKING_TEXT)) {
thinking = new TextDecoder().decode(thinkingMsg.get(FIELD.THINKING_TEXT)[0].value);
}
} catch (err) {
log("EXTRACT", `Thinking parse error: ${err.message}`);
}
}
return { text, thinking };
}
export function extractTextFromResponse(payload) {
try {
const fields = decodeMessage(payload);
// Warn about unknown field numbers — may indicate a Cursor protocol update
for (const fieldNum of fields.keys()) {
if (!KNOWN_RESPONSE_FIELDS.has(fieldNum)) {
log(
"SCHEMA",
`Unknown response field #${fieldNum} detected. Schema v${PROTOBUF_SCHEMA_VERSION} may be outdated.`
);
}
}
// Field 1: ClientSideToolV2Call
if (fields.has(FIELD.TOOL_CALL)) {
const toolCall = extractToolCall(fields.get(FIELD.TOOL_CALL)[0].value);
if (toolCall) {
log("EXTRACT", `Tool call: ${toolCall.function.name}`);
return { text: null, error: null, toolCall, thinking: null };
}
}
// Field 2: StreamUnifiedChatResponse
if (fields.has(FIELD.RESPONSE)) {
const { text, thinking } = extractTextAndThinking(fields.get(FIELD.RESPONSE)[0].value);
if (text || thinking) {
return { text, error: null, toolCall: null, thinking };
}
}
return { text: null, error: null, toolCall: null, thinking: null };
} catch (err) {
log("EXTRACT", `Decode failed (schema v${PROTOBUF_SCHEMA_VERSION}): ${err.message}`);
return {
text: null,
error: null,
toolCall: null,
thinking: null,
raw: Buffer.from(payload).toString("base64"),
decodeError: err.message
};
}
}
// ==================== EXPORTS ====================
export default {
encodeVarint,
encodeField,
encodeMessage,
buildChatRequest,
wrapConnectRPCFrame,
generateCursorBody,
decodeVarint,
decodeField,
decodeMessage,
parseConnectRPCFrame,
extractTextFromResponse
};