fix(api): widget throttling and orchestrator endpoints (#624)

Co-authored-by: Jason Woltje <jason@diversecanvas.com>
Co-committed-by: Jason Woltje <jason@diversecanvas.com>

apps/api/src/orchestrator/orchestrator.controller.ts

@@ -0,0 +1,115 @@
+import { Controller, Get, Res, UseGuards } from "@nestjs/common";
+import { AgentStatus } from "@prisma/client";
+import type { Response } from "express";
+import { AuthGuard } from "../auth/guards/auth.guard";
+import { PrismaService } from "../prisma/prisma.service";
+
+const AGENT_POLL_INTERVAL_MS = 5_000;
+const SSE_HEARTBEAT_MS = 15_000;
+
+interface OrchestratorAgentDto {
+  id: string;
+  name: string | null;
+  status: AgentStatus;
+  type: string;
+  createdAt: Date;
+}
+
+@Controller("orchestrator")
+@UseGuards(AuthGuard)
+export class OrchestratorController {
+  constructor(private readonly prisma: PrismaService) {}
+
+  @Get("agents")
+  async getAgents(): Promise<OrchestratorAgentDto[]> {
+    return this.fetchActiveAgents();
+  }
+
+  @Get("events")
+  async streamEvents(@Res() res: Response): Promise<void> {
+    res.setHeader("Content-Type", "text/event-stream");
+    res.setHeader("Cache-Control", "no-cache");
+    res.setHeader("Connection", "keep-alive");
+    res.setHeader("X-Accel-Buffering", "no");
+
+    if (typeof res.flushHeaders === "function") {
+      res.flushHeaders();
+    }
+
+    let isClosed = false;
+    let previousSnapshot = "";
+
+    const emitSnapshotIfChanged = async (): Promise<void> => {
+      if (isClosed) {
+        return;
+      }
+
+      try {
+        const agents = await this.fetchActiveAgents();
+        const snapshot = JSON.stringify(agents);
+
+        if (snapshot !== previousSnapshot) {
+          previousSnapshot = snapshot;
+          res.write(
+            `data: ${JSON.stringify({
+              type: "agents:updated",
+              agents,
+              timestamp: new Date().toISOString(),
+            })}\n\n`
+          );
+        }
+      } catch (error: unknown) {
+        const message = error instanceof Error ? error.message : String(error);
+        res.write(`event: error\n`);
+        res.write(`data: ${JSON.stringify({ error: message })}\n\n`);
+      }
+    };
+
+    await emitSnapshotIfChanged();
+
+    const pollInterval = setInterval(() => {
+      void emitSnapshotIfChanged();
+    }, AGENT_POLL_INTERVAL_MS);
+
+    const heartbeatInterval = setInterval(() => {
+      if (!isClosed) {
+        res.write(": keepalive\n\n");
+      }
+    }, SSE_HEARTBEAT_MS);
+
+    res.on("close", () => {
+      isClosed = true;
+      clearInterval(pollInterval);
+      clearInterval(heartbeatInterval);
+      res.end();
+    });
+  }
+
+  private async fetchActiveAgents(): Promise<OrchestratorAgentDto[]> {
+    const agents = await this.prisma.agent.findMany({
+      where: {
+        status: {
+          not: AgentStatus.TERMINATED,
+        },
+      },
+      orderBy: {
+        createdAt: "desc",
+      },
+      select: {
+        id: true,
+        name: true,
+        status: true,
+        role: true,
+        createdAt: true,
+      },
+    });
+
+    return agents.map((agent) => ({
+      id: agent.id,
+      name: agent.name,
+      status: agent.status,
+      type: agent.role ?? "agent",
+      createdAt: agent.createdAt,
+    }));
+  }
+}