Delve MCP

Instructions

Implementation Reference

• src/handlers/debug.ts:6-93 (handler)

  Handler function dispatched for 'trace' tool calls. Lacks specific implementation for 'trace' and will throw 'Unknown debug command' error.
  export async function handleDebugCommands(name: string, args: any) { switch (name) { case "debug": { const pkg = (args?.package as string) || "."; const buildFlags = args?.buildFlags as string | undefined; const cmdArgs: string[] = []; if (buildFlags) { cmdArgs.push("--build-flags", buildFlags); } const session = await startDebugSession("debug", pkg, cmdArgs); return { content: [{ type: "text", text: `Started debug session ${session.id} for package ${pkg}` }] }; } case "attach": { const pid = Number(args?.pid); if (!pid) { throw new Error("Process ID is required"); } const session = await startDebugSession("attach", pid.toString()); return { content: [{ type: "text", text: `Attached to process ${pid} with session ${session.id}` }] }; } case "exec": { const binary = String(args?.binary); const cmdArgs = (args?.args as string[]) || []; const session = await startDebugSession("exec", binary, cmdArgs); return { content: [{ type: "text", text: `Started debug session ${session.id} for binary ${binary}` }] }; } case "test": { const pkg = (args?.package as string) || "."; const testFlags = (args?.testFlags as string[]) || []; const session = await startDebugSession("test", pkg, ["--", ...testFlags]); return { content: [{ type: "text", text: `Started test debug session ${session.id} for package ${pkg}` }] }; } case "core": { const { executable, corePath } = args; const session = await startDebugSession("core", executable, [corePath]); return { content: [{ type: "text", text: `Started core dump analysis session ${session.id} for ${executable} with core ${corePath}` }] }; } case "dap": { const { clientAddr } = args; const cmdArgs = clientAddr ? ["--client-addr", clientAddr] : []; const session = await startDebugSession("dap", "", cmdArgs); return { content: [{ type: "text", text: `Started DAP server session ${session.id}${clientAddr ? ` connecting to ${clientAddr}` : ''}` }] }; } default: throw new Error("Unknown debug command"); }
• src/server.ts:320-348 (schema)

  Input schema and metadata for the 'trace' tool, listed in ListTools response.
  name: "trace", description: "Trace program execution", inputSchema: { type: "object", properties: { regexp: { type: "string", description: "Regular expression to match functions to trace" }, pkg: { type: "string", description: "Package to trace (defaults to .)" }, ebpf: { type: "boolean", description: "Use eBPF for tracing (experimental)" }, stack: { type: "number", description: "Show stack trace with given depth" }, pid: { type: "number", description: "Pid to attach to" } }, required: ["regexp"] } },
• src/server.ts:406-407 (registration)

  Dispatch logic in CallToolRequestSchema handler that routes 'trace' tool calls to handleDebugCommands.
  if (["debug", "attach", "exec", "test", "core", "dap", "replay", "trace"].includes(name)) { return handleDebugCommands(name, args);
• src/session.ts:35-64 (helper)

  Utility to start Delve debug session with given type ('trace') and arguments, spawning the 'dlv trace' process.
  export async function startDebugSession(type: string, target: string, args: string[] = []): Promise<DebugSession> { const port = await getAvailablePort(); const id = Math.random().toString(36).substring(7); const dlvArgs = [ type, "--headless", `--listen=:${port}`, "--accept-multiclient", "--api-version=2", target, ...args ]; const process = spawn("dlv", dlvArgs, { stdio: ["pipe", "pipe", "pipe"] }); const session: DebugSession = { id, type, target, process, port, breakpoints: new Map() }; sessions.set(id, session); return session; }
• src/types.ts:16-19 (schema)

  TypeScript type definition including 'trace' as a valid debug session type.
  export interface DebugSession { id: string; type: string; // 'debug' | 'attach' | 'exec' | 'test' | 'core' | 'replay' | 'trace' | 'dap' target: string;