fix(athena): harden council registration with duplicate detection and count validation

Three registration improvements: gate council member registration on Athena enablement, throw on duplicate council member keys instead of silent overwrite, and disable council mode when valid members drop below 2 after model parsing.

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

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

src/agents/builtin-agents.ts

@@ -19,6 +19,7 @@ import {
   fetchAvailableModels,
   readConnectedProvidersCache,
   readProviderModelsCache,
+  log,
 } from "../shared"
 import { CATEGORY_DESCRIPTIONS } from "../tools/delegate-task/constants"
 import { mergeCategories } from "../shared/merge-categories"
@@ -201,13 +202,13 @@ export async function createBuiltinAgents(
     result["atlas"] = atlasConfig
   }
 
-  if (councilConfig && councilConfig.members.length >= 2) {
+  if (councilConfig && councilConfig.members.length >= 2 && result["athena"]) {
     const { agents: councilAgents, registeredKeys } = registerCouncilMemberAgents(councilConfig)
     for (const [key, config] of Object.entries(councilAgents)) {
       result[key] = config
     }
 
-    if (result["athena"] && registeredKeys.length > 0) {
+    if (registeredKeys.length > 0) {
       const memberList = registeredKeys.map((key) => `- "${key}"`).join("\n")
       const councilTaskInstructions = `\n\n## Registered Council Members (use these as subagent_type in task calls)\n\n${memberList}`
       result["athena"] = {
@@ -215,6 +216,8 @@ export async function createBuiltinAgents(
         prompt: (result["athena"].prompt ?? "") + councilTaskInstructions,
       }
     }
+  } else if (councilConfig && councilConfig.members.length >= 2 && !result["athena"]) {
+    log("[builtin-agents] Skipping council member registration — Athena is disabled")
   }
 
   return result

src/agents/builtin-agents/council-member-agents.test.ts

@@ -0,0 +1,63 @@
+import { describe, expect, test } from "bun:test"
+import { registerCouncilMemberAgents } from "./council-member-agents"
+
+describe("council-member-agents", () => {
+  test("throws on duplicate model without name", () => {
+    //#given
+    const config = {
+      members: [
+        { model: "openai/gpt-5.3-codex" },
+        { model: "openai/gpt-5.3-codex" },
+      ],
+    }
+    //#when + #then
+    expect(() => registerCouncilMemberAgents(config)).toThrow("already registered")
+  })
+
+  test("registers different models without error", () => {
+    //#given
+    const config = {
+      members: [
+        { model: "openai/gpt-5.3-codex" },
+        { model: "anthropic/claude-opus-4-6" },
+      ],
+    }
+    //#when
+    const result = registerCouncilMemberAgents(config)
+    //#then
+    expect(result.registeredKeys).toHaveLength(2)
+    expect(result.registeredKeys).toContain("Council: GPT 5.3 Codex")
+    expect(result.registeredKeys).toContain("Council: Claude Opus 4.6")
+  })
+
+  test("allows same model with different names", () => {
+    //#given
+    const config = {
+      members: [
+        { model: "openai/gpt-5.3-codex", name: "GPT Codex" },
+        { model: "openai/gpt-5.3-codex", name: "Codex GPT" },
+      ],
+    }
+    //#when
+    const result = registerCouncilMemberAgents(config)
+    //#then
+    expect(result.registeredKeys).toHaveLength(2)
+    expect(result.agents).toHaveProperty("Council: GPT Codex")
+    expect(result.agents).toHaveProperty("Council: Codex GPT")
+  })
+
+  test("returns empty when valid members below 2", () => {
+    //#given - one valid model, one invalid (no slash separator)
+    const config = {
+      members: [
+        { model: "openai/gpt-5.3-codex" },
+        { model: "invalid-no-slash" },
+      ],
+    }
+    //#when
+    const result = registerCouncilMemberAgents(config)
+    //#then
+    expect(result.registeredKeys).toHaveLength(0)
+    expect(result.agents).toEqual({})
+  })
+})

src/agents/builtin-agents/council-member-agents.ts

@@ -71,11 +71,19 @@ export function registerCouncilMemberAgents(
     const friendlyName = member.name ?? humanizeModelId(member.model)
     const description = `Council member: ${friendlyName} (${member.model}). Independent read-only code analyst for Athena council. (OhMyOpenCode)`
 
+    if (agents[key]) {
+      const existingModel = agents[key].model ?? "unknown"
+      throw new Error(
+        `Council member key "${key}" is already registered (model: ${existingModel}). Use distinct "name" fields to avoid collisions.`
+      )
+    }
+
     agents[key] = {
       ...config,
       description,
       model: member.model,
       ...(member.variant ? { variant: member.variant } : {}),
+      ...(member.temperature !== undefined ? { temperature: member.temperature } : {}),
     }
 
     registeredKeys.push(key)
@@ -87,5 +95,10 @@ export function registerCouncilMemberAgents(
     })
   }
 
+  if (registeredKeys.length < 2) {
+    log("[council-member-agents] Fewer than 2 valid council members after model parsing — disabling council mode")
+    return { agents: {}, registeredKeys: [] }
+  }
+
   return { agents, registeredKeys }
 }