subagents (written by an agent, for an agent)

so meta.

gadget-drone/data/prompts/subagent/explore/system.md

@@ -8,8 +8,6 @@ You are spawned as a child process by the Master Control Console (MCC) in Gadget
 
 You will generally be tasked with exploring a software repository to learn about the software architecture, how things are imlemented, the structure of a class and it's methods, the order of operations as they are performed by the software, or even just read and summarize documentation looking for a specific piece of knowledge for the MCC.
 
-{{tool_aggression}}
-
 This is your job.
 
 ### CHAT SESSION

gadget-drone/data/prompts/subagent/general/system.md

@@ -8,8 +8,6 @@ You are spawned as a child process by the Master Control Console (MCC) in Gadget
 
 You will generally be tasked with exploring a software repository to learn about the software architecture, how things are imlemented, the structure of a class and it's methods, or even just read and summarize documentation looking for a specific piece of knowledge for the MCC.
 
-{{tool_aggression}}
-
 This is your job.
 
 ### CHAT SESSION

gadget-drone/src/services/agent.ts

@@ -2,23 +2,30 @@
 // Copyright (C) 2026 Rob Colbert <rob.colbert@openplatform.us>
 // Licensed under the Apache License, Version 2.0
 
+import path from "node:path";
+import fs from "node:fs/promises";
+
 import env from "../config/env.ts";
 
 import { Socket } from "socket.io-client";
 import {
-  IAiChatOptions,
+  type IAiChatOptions,
-  IAiChatResponse,
+  type IAiChatResponse,
-  IAiResponseStreamFn,
+  type IAiResponseStreamFn,
+  type IAiTool,
   type IContextChatMessage,
 } from "@gadget/ai";
 import {
-  IChatSession,
+  type IAiProvider,
-  IChatTurn,
+  type IChatSession,
-  IUser,
+  type IChatTurn,
-  ServerToClientEvents,
+  type IChatSubagentProcess,
-  ClientToServerEvents,
+  type IChatToolCall,
+  type IUser,
+  type ServerToClientEvents,
+  type ClientToServerEvents,
   ChatSessionMode,
-  IProject,
+  type IProject,
 } from "@gadget/api";
 
 import AiService from "./ai.ts";
@@ -40,6 +47,7 @@ import {
   PlanFileWriteTool,
   PlanListTool,
   ShellExecTool,
+  SubagentTool,
   type DroneToolboxEnvironment,
 } from "../tools/index.ts";
 
@@ -65,6 +73,8 @@ const toolboxEnv: DroneToolboxEnvironment = {
 
 class AgentService extends GadgetService {
   private toolbox = new AiToolbox(toolboxEnv);
+  private currentWorkOrder: IAgentWorkOrder | null = null;
+  private currentSocket: DroneSocket | null = null;
 
   get name(): string {
     return "AgentService";
@@ -109,10 +119,17 @@ class AgentService extends GadgetService {
     this.toolbox.register(new PlanFileEditTool(this.toolbox), [ChatSessionMode.Plan]);
     this.toolbox.register(new PlanListTool(this.toolbox), [ChatSessionMode.Plan]);
 
+    // Chat tools — subagent spawning: available in all modes
+    const subagentTool = new SubagentTool(this.toolbox);
+    subagentTool.setSpawner((agentType, prompt) => this.spawnSubagent(agentType, prompt));
+    this.toolbox.register(subagentTool, readOnlyModes);
+
     this.log.info("started");
   }
 
   async stop(): Promise<void> {
+    this.currentWorkOrder = null;
+    this.currentSocket = null;
     this.log.info("stopped");
   }
 
@@ -120,6 +137,9 @@ class AgentService extends GadgetService {
     workOrder: IAgentWorkOrder,
     socket: DroneSocket,
   ): Promise<void> {
+    this.currentWorkOrder = workOrder;
+    this.currentSocket = socket;
+
     const { turn } = workOrder;
     let toolCallCount = 0;
     let inputTokens = 0;
@@ -433,6 +453,259 @@ class AgentService extends GadgetService {
       cacheDir,
     });
   }
+
+  async spawnSubagent(
+    agentType: string,
+    prompt: string,
+  ): Promise<string> {
+    const workOrder = this.currentWorkOrder;
+    if (!workOrder) {
+      return JSON.stringify({
+        success: false,
+        error: "OPERATION_FAILED",
+        message: "No active work order. Subagent cannot be spawned outside of a work order.",
+      });
+    }
+
+    const turn = workOrder.turn;
+    const session = turn.session as IChatSession;
+
+    if (!session.user) {
+      return JSON.stringify({
+        success: false,
+        error: "OPERATION_FAILED",
+        message: "ChatSession must be populated with user data.",
+      });
+    }
+
+    const user = session.user as IUser;
+    const provider = turn.provider as IAiProvider;
+
+    if (!provider || typeof provider === "string") {
+      return JSON.stringify({
+        success: false,
+        error: "OPERATION_FAILED",
+        message: "Turn provider must be populated.",
+      });
+    }
+
+    // Build the subagent loop
+    const startTime = Date.now();
+    const systemPrompt = await this.buildSubagentSystemPrompt(agentType);
+    const messages: IContextChatMessage[] = [
+      { createdAt: new Date(), role: "system", content: systemPrompt },
+      { createdAt: new Date(), role: "user", content: prompt },
+    ];
+
+    const tools = this.getToolsForSubagent(agentType);
+    const streamHandler = this.currentSocket
+      ? this.makeStreamHandler(this.currentSocket)
+      : undefined;
+
+    let fullResponse = "";
+    let fullThinking = "";
+    const subagentToolCalls: IChatToolCall[] = [];
+    let toolCallCount = 0;
+    let inputTokens = 0;
+    let outputTokens = 0;
+    let thinkingTokenCount = 0;
+
+    try {
+      let continueLoop = true;
+      while (continueLoop) {
+        continueLoop = false;
+
+        const chatOptions: IAiChatOptions = {
+          context: messages,
+          tools,
+        };
+
+        this.log.info("subagent loop iteration", {
+          agentType,
+          messagesCount: messages.length,
+          toolsAvailable: tools.map((t) => t.name),
+        });
+
+        const response = await AiService.chat(
+          provider,
+          {
+            modelId: turn.llm,
+            params: { reasoning: false, temperature: 0.8, topP: 0.9, topK: 40 },
+          },
+          chatOptions,
+          streamHandler,
+        );
+
+        if (response.doneReason === "load" && !response.response && !response.thinking) {
+          throw new Error("Subagent model failed to respond (still loading or error)");
+        }
+
+        inputTokens += response.stats?.tokenCounts?.input ?? 0;
+        if (response.thinking) {
+          thinkingTokenCount += Math.ceil(response.thinking.length / 4);
+        }
+        if (response.response) {
+          fullResponse += response.response;
+          outputTokens += Math.ceil(response.response.length / 4);
+        }
+        if (response.thinking) {
+          fullThinking = (fullThinking + response.thinking).trim();
+        }
+
+        // Process tool calls
+        if (response.toolCalls && response.toolCalls.length > 0) {
+          continueLoop = true;
+          toolCallCount += response.toolCalls.length;
+
+          messages.push({
+            createdAt: new Date(),
+            role: "assistant",
+            content: response.response,
+          });
+
+          for (const toolCall of response.toolCalls) {
+            const toolArgsRaw = toolCall.function.arguments;
+            const result = await this.executeTool(
+              toolCall.function.name,
+              toolArgsRaw,
+            );
+
+            subagentToolCalls.push({
+              callId: toolCall.callId,
+              name: toolCall.function.name,
+              parameters: toolArgsRaw,
+              response: result,
+            });
+
+            messages.push({
+              createdAt: new Date(),
+              role: "tool",
+              callId: toolCall.callId,
+              toolName: toolCall.function.name,
+              content: result,
+            });
+
+            inputTokens += Math.ceil(toolArgsRaw.length / 4);
+            outputTokens += Math.ceil(result.length / 4);
+          }
+        }
+      }
+
+      // Ensure we have a response if the subagent only made tool calls
+      if (!fullResponse.trim()) {
+        if (toolCallCount > 0) {
+          fullResponse = `Subagent task completed. Executed ${toolCallCount} tool calls to perform the requested actions.`;
+        } else {
+          fullResponse = "Subagent task completed without additional actions.";
+        }
+      }
+
+      const endTime = Date.now();
+      const durationMs = endTime - startTime;
+      const durationSeconds = Math.floor(durationMs / 1000);
+      const minutes = Math.floor(durationSeconds / 60);
+      const seconds = durationSeconds % 60;
+      const durationLabel = `${String(minutes).padStart(2, "0")}:${String(seconds).padStart(2, "00")}`;
+
+      const result: IChatSubagentProcess = {
+        prompt,
+        thinking: fullThinking || undefined,
+        response: fullResponse,
+        toolCalls: subagentToolCalls,
+        stats: {
+          toolCallCount,
+          inputTokens,
+          thinkingTokenCount,
+          responseTokens: outputTokens,
+          durationMs,
+          durationLabel,
+        },
+      };
+
+      return JSON.stringify({ success: true, data: result });
+    } catch (error) {
+      const errorMessage = error instanceof Error ? error.message : String(error);
+      this.log.error("subagent execution failed", { agentType, error: errorMessage });
+
+      return JSON.stringify({
+        success: false,
+        error: "SUBAGENT_FAILED",
+        message: errorMessage,
+      });
+    }
+  }
+
+  private getToolsForSubagent(agentType: string): IAiTool[] {
+    const mode = agentType === "explore"
+      ? ChatSessionMode.Plan
+      : ChatSessionMode.Build;
+
+    const tools = Array.from(this.toolbox.getModeSet(mode) || []);
+
+    if (agentType === "explore") {
+      return tools.filter((t) =>
+        !t.name.startsWith("plan_") &&
+        t.name !== "subagent"
+      );
+    }
+
+    return tools.filter((t) => t.name !== "subagent");
+  }
+
+  private async buildSubagentSystemPrompt(agentType: string): Promise<string> {
+    const promptDir = path.resolve(env.installDir, "data", "prompts", "subagent", agentType);
+    const templatePath = path.join(promptDir, "system.md");
+
+    let template: string;
+    try {
+      template = await fs.readFile(templatePath, "utf-8");
+    } catch {
+      this.log.error("subagent prompt template not found", { agentType, templatePath });
+      throw new Error(`Subagent prompt template not found: ${templatePath}`);
+    }
+
+    const workOrder = this.currentWorkOrder;
+    if (!workOrder) return template;
+
+    const session = workOrder.turn.session as IChatSession;
+    const user = session?.user as IUser | undefined;
+    const project = session?.project as IProject | undefined;
+    const provider = workOrder.turn.provider as IAiProvider | undefined;
+
+    // Build session block matching the format used in gadget-code's buildSystemPrompt
+    const sessionBlock = [
+      `Session ID: ${session?._id ?? "unknown"}`,
+      `Session Name: ${session?.name ?? "unknown"}`,
+      `Session Created: ${session?.createdAt?.toISOString() ?? "unknown"}`,
+      `AI Provider: ${provider?.name ?? "unknown"}`,
+      `AI API: ${provider?.apiType ?? "unknown"}`,
+      `Model: ${workOrder.turn.llm}`,
+      `Project: ${project?.name ?? "unknown"}`,
+    ].join("\n");
+
+    const personaBlock = [
+      `User ID: ${user?._id ?? "unknown"}`,
+      `Name: ${user?.displayName ?? "unknown"}`,
+      `Is Admin: ${user?.flags?.isAdmin ? "Yes" : "No"}`,
+    ].join("\n");
+
+    template = template.replace("{{session_block}}", sessionBlock);
+    template = template.replace("{{persona_block}}", personaBlock);
+
+    // Append AGENTS.md if available in the project root
+    try {
+      const projectRoot = this.toolbox.env.workspace?.projectDir;
+      if (projectRoot) {
+        const agentsMdPath = path.join(projectRoot, "AGENTS.md");
+        const agentsMd = await fs.readFile(agentsMdPath, "utf-8");
+        template += "\n\n## AGENT CONFIGURATION\n\n" + agentsMd;
+      }
+    } catch {
+      // AGENTS.md not found or inaccessible - that's fine
+    }
+
+    return template;
+  }
 }
 
 export { AgentService };

gadget-drone/src/tools/chat/index.ts

@@ -0,0 +1,4 @@
+// Copyright (C) 2026 Rob Colbert <rob.colbert@openplatform.us>
+// Licensed under the Apache License, Version 2.0
+
+export { SubagentTool } from "./subagent.ts";

gadget-drone/src/tools/chat/subagent.ts

@@ -0,0 +1,108 @@
+// Copyright (C) 2026 Rob Colbert <rob.colbert@openplatform.us>
+// Licensed under the Apache License, Version 2.0
+
+import type { IAiLogger, IToolArguments, IToolDefinition } from "@gadget/ai";
+import { formatError } from "@gadget/ai";
+import { DroneTool } from "../tool.ts";
+
+const VALID_AGENT_TYPES = ["explore", "general"] as const;
+type AgentType = (typeof VALID_AGENT_TYPES)[number];
+
+export class SubagentTool extends DroneTool {
+  private _spawnSubagent: ((agentType: string, prompt: string) => Promise<string>) | null = null;
+
+  setSpawner(fn: typeof this._spawnSubagent): void {
+    this._spawnSubagent = fn;
+  }
+
+  get name(): string {
+    return "subagent";
+  }
+
+  get category(): string {
+    return "chat";
+  }
+
+  get definition(): IToolDefinition {
+    return {
+      type: "function",
+      function: {
+        name: this.name,
+        description:
+          "Spawn a subagent to perform a specific task. The subagent will execute the task and return its result. Use 'explore' agent type for research and information gathering tasks. Use 'general' agent type for general-purpose task execution.",
+        parameters: {
+          type: "object",
+          properties: {
+            agent_type: {
+              type: "string",
+              enum: [...VALID_AGENT_TYPES],
+              description:
+                "The type of subagent to spawn. Use 'explore' for research and information gathering. Use 'general' for general-purpose task execution.",
+            },
+            prompt: {
+              type: "string",
+              description:
+                "The task description and instructions for the subagent. Be specific about what information to find or what task to perform.",
+            },
+          },
+          required: ["agent_type", "prompt"],
+        },
+      },
+    };
+  }
+
+  async execute(args: IToolArguments, logger: IAiLogger): Promise<string> {
+    const { agent_type, prompt } = args;
+
+    if (!agent_type) {
+      return formatError({
+        code: "MISSING_PARAMETER",
+        message: "The 'agent_type' parameter is required.",
+        parameter: "agent_type",
+        expected: "Either 'explore' or 'general'",
+        recoveryHint: "Specify either 'explore' or 'general' for the agent_type parameter.",
+      });
+    }
+
+    if (!VALID_AGENT_TYPES.includes(agent_type as AgentType)) {
+      return formatError({
+        code: "INVALID_PARAMETER",
+        message: `Invalid agent_type: '${agent_type}'. Must be one of: ${VALID_AGENT_TYPES.join(", ")}`,
+        parameter: "agent_type",
+        expected: `One of: ${VALID_AGENT_TYPES.join(", ")}`,
+        recoveryHint: "Use 'explore' for research tasks or 'general' for general tasks.",
+      });
+    }
+
+    if (!prompt || typeof prompt !== "string") {
+      return formatError({
+        code: "MISSING_PARAMETER",
+        message: "The 'prompt' parameter is required and must be a string.",
+        parameter: "prompt",
+        expected: "A non-empty string describing the task for the subagent.",
+        recoveryHint: "Provide specific instructions for the subagent to execute.",
+      });
+    }
+
+    if (!this._spawnSubagent) {
+      return formatError({
+        code: "OPERATION_FAILED",
+        message: "SubagentTool has not been initialized with a spawner function.",
+      });
+    }
+
+    logger.debug("spawning subagent", { agentType: agent_type, promptLength: (prompt as string).length });
+
+    try {
+      return await this._spawnSubagent(agent_type as string, prompt as string);
+    } catch (error) {
+      const message = error instanceof Error ? error.message : String(error);
+      logger.error("subagent execution failed", { agentType: agent_type, error: message });
+      return JSON.stringify({
+        success: false,
+        error: "SUBAGENT_FAILED",
+        message,
+      });
+    }
+  }
+}

gadget-drone/src/tools/index.ts

@@ -3,6 +3,7 @@
 
 export { AiToolbox, type DroneToolboxEnvironment } from "./toolbox.ts";
 export { DroneTool } from "./tool.ts";
+export * from "./chat/index.ts";
 export * from "./system/index.ts";
 export * from "./network/index.ts";
 export * from "./plan/index.ts";