fix(agents): add anti-duplication rules to Prometheus and Metis agents

- Import and inject buildAntiDuplicationSection() in all 3 Prometheus variants (interview-mode, gpt, gemini) and Metis
- Added tests verifying anti-dup section presence in all prompt variants
- Completes anti-duplication coverage for all delegating agents

src/agents/prometheus-prompt.test.ts

@@ -1,5 +1,7 @@
 import { describe, test, expect } from "bun:test"
 import { PROMETHEUS_SYSTEM_PROMPT } from "./prometheus"
+import { PROMETHEUS_GPT_SYSTEM_PROMPT } from "./prometheus/gpt"
+import { PROMETHEUS_GEMINI_SYSTEM_PROMPT } from "./prometheus/gemini"
 
 describe("PROMETHEUS_SYSTEM_PROMPT Momus invocation policy", () => {
   test("should direct providing ONLY the file path string when invoking Momus", () => {
@@ -82,3 +84,22 @@ describe("PROMETHEUS_SYSTEM_PROMPT zero human intervention", () => {
     expect(lowerPrompt).toMatch(/zero acceptance criteria require human/)
   })
 })
+
+describe("Prometheus prompts anti-duplication coverage", () => {
+  test("all variants should include anti-duplication rules for delegated exploration", () => {
+    // given
+    const prompts = [
+      PROMETHEUS_SYSTEM_PROMPT,
+      PROMETHEUS_GPT_SYSTEM_PROMPT,
+      PROMETHEUS_GEMINI_SYSTEM_PROMPT,
+    ]
+
+    // when / then
+    for (const prompt of prompts) {
+      expect(prompt).toContain("<Anti_Duplication>")
+      expect(prompt).toContain("Anti-Duplication Rule")
+      expect(prompt).toContain("DO NOT perform the same search yourself")
+      expect(prompt).toContain("non-overlapping work")
+    }
+  })
+})