feat(examples): Add supervisor example

examples/src/createAgent/supervisor.ts

@@ -0,0 +1,374 @@
+/**
+ * Complete Personal Assistant Supervisor Example with Human-in-the-Loop
+ *
+ * This example demonstrates:
+ * 1. The tool calling pattern for multi-agent systems
+ * 2. Human-in-the-loop review of sensitive actions
+ * 3. Approve/edit/reject decisions for tool calls
+ *
+ * A supervisor agent coordinates specialized sub-agents (calendar and email)
+ * that are wrapped as tools, with human approval for sensitive operations.
+ *
+ * This example is designed to accompany the supervisor tutorial:
+ *
+ * https://docs.langchain.com/oss/javascript/langchain/supervisor
+ */
+
+import { ChatAnthropic } from "@langchain/anthropic";
+import { HumanMessage } from "@langchain/core/messages";
+import {
+  Command,
+  getCurrentTaskInput,
+  MemorySaver,
+} from "@langchain/langgraph";
+import { createAgent, humanInTheLoopMiddleware, tool } from "langchain";
+import { z } from "zod";
+
+// ============================================================================
+// Step 1: Define low-level API tools (stubbed)
+// ============================================================================
+
+const createCalendarEvent = tool(
+  async ({ title, startTime, endTime, attendees, location }) => {
+    // Stub: In practice, this would call Google Calendar API, Outlook API, etc.
+    return `Event created: ${title} from ${startTime} to ${endTime} with ${attendees.length} attendees`;
+  },
+  {
+    name: "create_calendar_event",
+    description: "Create a calendar event. Requires exact ISO datetime format.",
+    schema: z.object({
+      title: z.string(),
+      startTime: z.string().describe("ISO format: '2024-01-15T14:00:00'"),
+      endTime: z.string().describe("ISO format: '2024-01-15T15:00:00'"),
+      attendees: z.array(z.string()).describe("email addresses"),
+      location: z.string().optional().default(""),
+    }),
+  }
+);
+
+const sendEmail = tool(
+  async ({ to, subject, body, cc }) => {
+    // Stub: In practice, this would call SendGrid, Gmail API, etc.
+    return `Email sent to ${to.join(", ")} - Subject: ${subject}`;
+  },
+  {
+    name: "send_email",
+    description:
+      "Send an email via email API. Requires properly formatted addresses.",
+    schema: z.object({
+      to: z.array(z.string()).describe("email addresses"),
+      subject: z.string(),
+      body: z.string(),
+      cc: z.array(z.string()).optional().default([]),
+    }),
+  }
+);
+
+const getAvailableTimeSlots = tool(
+  async ({ attendees, date, durationMinutes }) => {
+    // Stub: In practice, this would query calendar APIs
+    return ["09:00", "14:00", "16:00"];
+  },
+  {
+    name: "get_available_time_slots",
+    description:
+      "Check calendar availability for given attendees on a specific date.",
+    schema: z.object({
+      attendees: z.array(z.string()),
+      date: z.string().describe("ISO format: '2024-01-15'"),
+      durationMinutes: z.number(),
+    }),
+  }
+);
+
+// ============================================================================
+// Step 2: Create specialized sub-agents with human-in-the-loop middleware
+// ============================================================================
+
+const llm = new ChatAnthropic({
+  model: "claude-sonnet-4-5-20250929",
+});
+
+const CALENDAR_AGENT_PROMPT = `
+You are a calendar scheduling assistant.
+Parse natural language scheduling requests (e.g., 'next Tuesday at 2pm')
+into proper ISO datetime formats.
+Use get_available_time_slots to check availability when needed.
+Use create_calendar_event to schedule events.
+Always confirm what was scheduled in your final response.
+`.trim();
+
+const EMAIL_AGENT_PROMPT = `
+You are an email assistant.
+Compose professional emails based on natural language requests.
+Extract recipient information and craft appropriate subject lines and body text.
+Use send_email to send the message.
+Always confirm what was sent in your final response.
+`.trim();
+
+const calendarAgent = createAgent({
+  model: llm,
+  tools: [createCalendarEvent, getAvailableTimeSlots],
+  systemPrompt: CALENDAR_AGENT_PROMPT,
+  middleware: [
+    humanInTheLoopMiddleware({
+      interruptOn: { create_calendar_event: true },
+      descriptionPrefix: "Calendar event pending approval",
+    }),
+  ],
+});
+
+const emailAgent = createAgent({
+  model: llm,
+  tools: [sendEmail],
+  systemPrompt: EMAIL_AGENT_PROMPT,
+  middleware: [
+    humanInTheLoopMiddleware({
+      interruptOn: { send_email: true },
+      descriptionPrefix: "Outbound email pending approval",
+    }),
+  ],
+});
+
+// ============================================================================
+// Step 3: Wrap sub-agents as tools for the supervisor
+// ============================================================================
+
+const scheduleEvent = tool(
+  async ({ request }, config) => {
+    // Customize context received by sub-agent
+    // Access full thread messages from the config
+    const currentMessages =
+      getCurrentTaskInput<InternalAgentState>(config).messages;
+
+    const originalUserMessage = currentMessages.find(HumanMessage.isInstance);
+
+    const prompt = `
+You are assisting with the following user inquiry:
+
+${originalUserMessage?.content || "No context available"}
+
+You are tasked with the following sub-request:
+
+${request}
+    `.trim();
+
+    const result = await calendarAgent.invoke({
+      messages: [{ role: "user", content: prompt }],
+    });
+    const lastMessage = result.messages[result.messages.length - 1];
+    return lastMessage.text;
+  },
+  {
+    name: "schedule_event",
+    description: `
+Schedule calendar events using natural language.
+
+Use this when the user wants to create, modify, or check calendar appointments.
+Handles date/time parsing, availability checking, and event creation.
+
+Input: Natural language scheduling request (e.g., 'meeting with design team next Tuesday at 2pm')
+    `.trim(),
+    schema: z.object({
+      request: z.string().describe("Natural language scheduling request"),
+    }),
+  }
+);
+
+const manageEmail = tool(
+  async ({ request }, config) => {
+    // Customize context received by sub-agent
+    // Access full thread messages from the config
+    const currentMessages =
+      getCurrentTaskInput<InternalAgentState>(config).messages;
+
+    const originalUserMessage = currentMessages.find(HumanMessage.isInstance);
+
+    const prompt = `
+You are assisting with the following user inquiry:
+
+${originalUserMessage?.content || "No context available"}
+
+You are tasked with the following sub-request:
+
+${request}
+    `.trim();
+
+    const result = await emailAgent.invoke({
+      messages: [{ role: "user", content: prompt }],
+    });
+    const lastMessage = result.messages[result.messages.length - 1];
+    return lastMessage.text;
+  },
+  {
+    name: "manage_email",
+    description: `
+Send emails using natural language.
+
+Use this when the user wants to send notifications, reminders, or any email communication.
+Handles recipient extraction, subject generation, and email composition.
+
+Input: Natural language email request (e.g., 'send them a reminder about the meeting')
+    `.trim(),
+    schema: z.object({
+      request: z.string().describe("Natural language email request"),
+    }),
+  }
+);
+
+// ============================================================================
+// Step 4: Create the supervisor agent with checkpointer
+// ============================================================================
+
+const SUPERVISOR_PROMPT = `
+You are a helpful personal assistant.
+You can schedule calendar events and send emails.
+Break down user requests into appropriate tool calls and coordinate the results.
+When a request involves multiple actions, use multiple tools in sequence.
+`.trim();
+
+const supervisorAgent = createAgent({
+  model: llm,
+  tools: [scheduleEvent, manageEmail],
+  systemPrompt: SUPERVISOR_PROMPT,
+  checkpointer: new MemorySaver(),
+});
+
+// ============================================================================
+// Step 5: Demonstrate the complete workflow with human-in-the-loop
+// ============================================================================
+
+async function main() {
+  const query =
+    "Schedule a meeting with the design team ([email protected], [email protected]) " +
+    "on January 28, 2025 at 2pm for 1 hour titled 'Design Review', " +
+    "and send them an email reminder about reviewing the new mockups.";
+
+  const config = { configurable: { thread_id: "6" } };
+
+  console.log("User Request:", query);
+  console.log(`\n${"=".repeat(80)}\n`);
+
+  // Initial stream - will interrupt for human approval
+  console.log("=== Initial Request (will interrupt for approval) ===\n");
+
+  const interrupts: any[] = [];
+  const stream = await supervisorAgent.stream(
+    { messages: [{ role: "user", content: query }] },
+    config
+  );
+
+  for await (const step of stream) {
+    for (const update of Object.values(step)) {
+      if (update && typeof update === "object" && "messages" in update) {
+        for (const message of (update as any).messages) {
+          console.log(message.prettyPrint());
+        }
+      } else if (Array.isArray(update)) {
+        const interrupt = update[0];
+        interrupts.push(interrupt);
+        console.log(`\nINTERRUPTED: ${interrupt.id}`);
+      }
+    }
+  }
+
+  // Inspect the interrupts
+  console.log(`\n${"=".repeat(80)}\n`);
+  console.log("=== Inspecting Interrupts ===\n");
+
+  for (const interrupt of interrupts) {
+    for (const request of interrupt.value.actionRequests) {
+      console.log(`INTERRUPTED: ${interrupt.id}`);
+      console.log(`${request.description}\n`);
+    }
+  }
+
+  // Build resume decisions: approve calendar, edit email subject
+  console.log(`${"=".repeat(80)}\n`);
+  console.log("=== Resuming with Decisions ===");
+  console.log("- Approving calendar event");
+  console.log("- Editing email subject to 'Mockups reminder'\n");
+
+  const resume: Record<string, any> = {};
+  for (const interrupt of interrupts) {
+    // Check which interrupt this is by inspecting the tool
+    const actionRequest = interrupt.value.actionRequests[0];
+
+    if (actionRequest.name === "send_email") {
+      // Edit email subject
+      const editedAction = { ...actionRequest };
+      editedAction.arguments.subject = "Mockups reminder";
+      resume[interrupt.id] = {
+        decisions: [{ type: "edit", editedAction }],
+      };
+    } else {
+      // Approve everything else
+      resume[interrupt.id] = { decisions: [{ type: "approve" }] };
+    }
+  }
+
+  const resumeStream = await supervisorAgent.stream(
+    new Command({ resume }),
+    config
+  );
+
+  const moreInterrupts: any[] = [];
+  for await (const step of resumeStream) {
+    for (const update of Object.values(step)) {
+      if (update && typeof update === "object" && "messages" in update) {
+        for (const message of (update as any).messages) {
+          console.log(message.prettyPrint());
+        }
+      } else if (Array.isArray(update)) {
+        const interrupt = update[0];
+        moreInterrupts.push(interrupt);
+        console.log(`\nINTERRUPTED: ${interrupt.id}`);
+      }
+    }
+  }
+
+  // Handle any additional interrupts (e.g., for the email)
+  if (moreInterrupts.length > 0) {
+    console.log(`\n${"=".repeat(80)}\n`);
+    console.log("=== Additional Interrupts (Email) ===\n");
+
+    for (const interrupt of moreInterrupts) {
+      for (const request of interrupt.value.actionRequests) {
+        console.log(`INTERRUPTED: ${interrupt.id}`);
+        console.log(`${request.description}\n`);
+      }
+    }
+
+    console.log(`${"=".repeat(80)}\n`);
+    console.log("=== Approving Email ===\n");
+
+    // Approve the email interrupt
+    const finalResume: Record<string, any> = {};
+    for (const interrupt of moreInterrupts) {
+      finalResume[interrupt.id] = { decisions: [{ type: "approve" }] };
+    }
+
+    const finalStream = await supervisorAgent.stream(
+      new Command({ resume: finalResume }),
+      config
+    );
+
+    for await (const step of finalStream) {
+      for (const update of Object.values(step)) {
+        if (update && typeof update === "object" && "messages" in update) {
+          for (const message of (update as any).messages) {
+            console.log(message.prettyPrint());
+          }
+        }
+      }
+    }
+  }
+
+  console.log(`\n${"=".repeat(80)}`);
+  console.log(
+    "\n✅ Complete! The supervisor coordinated both agents with human approval."
+  );
+}
+
+// Run the example
+main().catch(console.error);