feat(athena): register council members as task-callable subagents

Each council member from config is now registered as a named agent (e.g. 'Council: Claude Opus 4.6') via registerCouncilMemberAgents(). Adds humanizeModelId() to derive friendly display names from model IDs. Athena's prompt gets the member list appended so it can call task(subagent_type=...) for each.

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

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

src/agents/builtin-agents.ts

@@ -28,6 +28,8 @@ import { collectPendingBuiltinAgents } from "./builtin-agents/general-agents"
 import { maybeCreateSisyphusConfig } from "./builtin-agents/sisyphus-agent"
 import { maybeCreateHephaestusConfig } from "./builtin-agents/hephaestus-agent"
 import { maybeCreateAtlasConfig } from "./builtin-agents/atlas-agent"
+import { registerCouncilMemberAgents } from "./builtin-agents/council-member-agents"
+import type { CouncilConfig } from "./athena/types"
 
 type AgentSource = AgentFactory | AgentConfig
 
@@ -76,7 +78,8 @@ export async function createBuiltinAgents(
   uiSelectedModel?: string,
   disabledSkills?: Set<string>,
   useTaskSystem = false,
-  disableOmoEnv = false
+  disableOmoEnv = false,
+  councilConfig?: CouncilConfig
 ): Promise<Record<string, AgentConfig>> {
 
   const connectedProviders = readConnectedProvidersCache()
@@ -183,5 +186,21 @@ export async function createBuiltinAgents(
     result["atlas"] = atlasConfig
   }
 
+  if (councilConfig && councilConfig.members.length >= 2) {
+    const { agents: councilAgents, registeredKeys } = registerCouncilMemberAgents(councilConfig)
+    for (const [key, config] of Object.entries(councilAgents)) {
+      result[key] = config
+    }
+
+    if (result["athena"] && 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"] = {
+        ...result["athena"],
+        prompt: (result["athena"].prompt ?? "") + councilTaskInstructions,
+      }
+    }
+  }
+
   return result
 }