Multi-agent system with coordinator, researcher, fact-checker, and writer

.github/workflows/ci.yml

@@ -0,0 +1,30 @@
+name: CI
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+    branches: [main]
+
+jobs:
+  typecheck:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-node@v4
+        with:
+          node-version: 22
+          cache: npm
+      - run: npm ci
+      - run: npm run typecheck
+
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-node@v4
+        with:
+          node-version: 22
+          cache: npm
+      - run: npm ci
+      - run: npm run build

README.md

@@ -4,21 +4,23 @@ Multi-agent system built on the Anthropic TypeScript SDK (`@anthropic-ai/sdk`).
 
 ## Architecture
 
-A **coordinator** agent (Opus 4.8) orchestrates two specialist subagents via tool calls:
+A **coordinator** agent (Opus 4.8) orchestrates three specialist subagents via tool calls:
 
 - `delegate_research(topic)` → research subagent (Haiku 4.5 + `web_search`) returns a JSON summary with sources.
+- `delegate_fact_check(topic)` → fact-checker subagent (Haiku 4.5) verifies findings for contradictions, unsupported claims, and gaps.
 - `delegate_writing(topic)` → writer subagent (Opus 4.8 + adaptive thinking) produces the final markdown report.
 
-Each subagent runs its own tool-runner loop. The coordinator decides when to fan out research and when to write.
+Each subagent runs its own loop. The coordinator follows a research → verify → write workflow.
 
 ```
 user request
      │
      ▼
 coordinator (Opus 4.8)
-  ├── delegate_research ──▶ researcher (Haiku 4.5 + web_search)
-  ├── delegate_research ──▶ researcher
-  └── delegate_writing  ──▶ writer (Opus 4.8)
+  ├── delegate_research    ──▶ researcher (Haiku 4.5 + web_search)
+  ├── delegate_research    ──▶ researcher
+  ├── delegate_fact_check  ──▶ fact-checker (Haiku 4.5)
+  └── delegate_writing     ──▶ writer (Opus 4.8)
 ```
 
 ## Setup
@@ -44,6 +46,7 @@ npm run research -- "TypeScript 5.7 changes"
 
 - `src/client.ts` — shared Anthropic client + model IDs.
 - `src/agents/researcher.ts` — research subagent (web search + structured summary tool).
+- `src/agents/fact-checker.ts` — fact-checker subagent (verifies findings before writing).
 - `src/agents/writer.ts` — writer subagent (adaptive thinking, no tools).
 - `src/coordinator.ts` — top-level coordinator exposing subagents as tools.
 - `src/index.ts` — CLI entry point.

package.json

@@ -11,12 +11,12 @@
     "typecheck": "tsc --noEmit"
   },
   "dependencies": {
-    "@anthropic-ai/sdk": "^0.88.0",
-    "zod": "^3.23.8"
+    "@anthropic-ai/sdk": "^0.105.0",
+    "zod": "^4.4.3"
   },
   "devDependencies": {
-    "@types/node": "^22.10.0",
+    "@types/node": "^26.0.0",
     "tsx": "^4.19.0",
-    "typescript": "^5.7.0"
+    "typescript": "^6.0.3"
   }
 }

src/agents/fact-checker.ts

@@ -0,0 +1,26 @@
+import { client, FAST_MODEL } from "../client.js";
+
+export async function factCheck(
+  topic: string,
+  findings: string[],
+): Promise<string> {
+  const response = await client.messages.create({
+    model: FAST_MODEL,
+    max_tokens: 4000,
+    system:
+      "You are a fact-checker subagent. Given a topic and research findings, identify any contradictions, unsupported claims, or gaps. Return a JSON object with: { verified: string[], disputed: string[], gaps: string[] }. Be concise.",
+    messages: [
+      {
+        role: "user",
+        content: `Topic: ${topic}\n\nFindings to verify:\n${findings
+          .map((f, i) => `[${i + 1}] ${f}`)
+          .join("\n\n")}\n\nAnalyze these findings now.`,
+      },
+    ],
+  });
+
+  return response.content
+    .filter((b) => b.type === "text")
+    .map((b) => (b.type === "text" ? b.text : ""))
+    .join("");
+}

src/coordinator.ts

@@ -3,6 +3,7 @@ import { z } from "zod";
 import { client, MODEL } from "./client.js";
 import { research } from "./agents/researcher.js";
 import { writeReport } from "./agents/writer.js";
+import { factCheck } from "./agents/fact-checker.js";
 
 // Hand-off pattern: the coordinator exposes subagents as tools.
 // Each tool call delegates to a specialized agent and returns its output.
@@ -23,6 +24,21 @@ const delegateResearch = betaZodTool({
   },
 });
 
+const delegateFactCheck = betaZodTool({
+  name: "delegate_fact_check",
+  description:
+    "Delegate fact-checking to the fact-checker subagent. Call after research and before writing to verify findings. Returns verified/disputed/gaps analysis.",
+  inputSchema: z.object({
+    topic: z.string(),
+  }),
+  run: async ({ topic }) => {
+    if (findings.length === 0) {
+      return "Error: call delegate_research at least once before fact-checking.";
+    }
+    return await factCheck(topic, findings);
+  },
+});
+
 const delegateWriting = betaZodTool({
   name: "delegate_writing",
   description:
@@ -44,12 +60,13 @@ export async function runCoordinator(userRequest: string): Promise<string> {
     max_tokens: 32000,
     thinking: { type: "adaptive" },
     output_config: { effort: "high" },
-    system: `You are a coordinator agent orchestrating two subagents:
+    system: `You are a coordinator agent orchestrating three subagents:
 - delegate_research(topic): fan-out research queries; call multiple times in parallel for independent subtopics.
-- delegate_writing(topic): once you have enough findings, produce the final report.
+- delegate_fact_check(topic): after research, verify findings for contradictions, unsupported claims, and gaps.
+- delegate_writing(topic): once findings are verified, produce the final report.
 
-Plan first, then delegate. Return the final report verbatim.`,
-    tools: [delegateResearch, delegateWriting],
+Workflow: research → fact-check → write. Return the final report verbatim.`,
+    tools: [delegateResearch, delegateFactCheck, delegateWriting],
     messages: [{ role: "user", content: userRequest }],
   });