fix: prevent agents from duplicating delegated subagent work

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

src/agents/anti-duplication.test.ts

@@ -0,0 +1,92 @@
+/// <reference types="bun-types" />
+
+import { describe, it, expect } from "bun:test"
+import { buildAntiDuplicationSection } from "./dynamic-agent-prompt-builder"
+
+describe("buildAntiDuplicationSection", () => {
+  it("#given no arguments #when building anti-duplication section #then returns comprehensive rule section", () => {
+    //#given: no special configuration needed
+
+    //#when: building the anti-duplication section
+    const result = buildAntiDuplicationSection()
+
+    //#then: should contain the anti-duplication rule with all key concepts
+    expect(result).toContain("Anti-Duplication Rule")
+    expect(result).toContain("CRITICAL")
+    expect(result).toContain("DO NOT perform the same search yourself")
+  })
+
+  it("#given no arguments #when building #then explicitly forbids manual re-search after delegation", () => {
+    //#given: no special configuration
+
+    //#when: building the section
+    const result = buildAntiDuplicationSection()
+
+    //#then: should explicitly list forbidden behaviors
+    expect(result).toContain("FORBIDDEN")
+    expect(result).toContain("manually grep/search for the same information")
+    expect(result).toContain("Re-doing the research")
+  })
+
+  it("#given no arguments #when building #then allows non-overlapping work", () => {
+    //#given: no special configuration
+
+    //#when: building the section
+    const result = buildAntiDuplicationSection()
+
+    //#then: should explicitly allow non-overlapping work
+    expect(result).toContain("ALLOWED")
+    expect(result).toContain("non-overlapping work")
+    expect(result).toContain("work that doesn't depend on the delegated research")
+  })
+
+  it("#given no arguments #when building #then includes wait-for-results instructions", () => {
+    //#given: no special configuration
+
+    //#when: building the section
+    const result = buildAntiDuplicationSection()
+
+    //#then: should include instructions for waiting properly
+    expect(result).toContain("Wait for Results Properly")
+    expect(result).toContain("End your response")
+    expect(result).toContain("Wait for the completion notification")
+    expect(result).toContain("background_output")
+  })
+
+  it("#given no arguments #when building #then explains why this matters", () => {
+    //#given: no special configuration
+
+    //#when: building the section
+    const result = buildAntiDuplicationSection()
+
+    //#then: should explain the purpose
+    expect(result).toContain("Why This Matters")
+    expect(result).toContain("Wasted tokens")
+    expect(result).toContain("Confusion")
+    expect(result).toContain("Efficiency")
+  })
+
+  it("#given no arguments #when building #then provides code examples", () => {
+    //#given: no special configuration
+
+    //#when: building the section
+    const result = buildAntiDuplicationSection()
+
+    //#then: should include examples
+    expect(result).toContain("Example")
+    expect(result).toContain("WRONG")
+    expect(result).toContain("CORRECT")
+    expect(result).toContain("task(subagent_type=")
+  })
+
+  it("#given no arguments #when building #then uses proper markdown formatting", () => {
+    //#given: no special configuration
+
+    //#when: building the section
+    const result = buildAntiDuplicationSection()
+
+    //#then: should be wrapped in Anti_Duplication tag
+    expect(result).toContain("<Anti_Duplication>")
+    expect(result).toContain("</Anti_Duplication>")
+  })
+})