diff --git a/scripts/build.ts b/scripts/build.ts
index 2982f1f8..52b7953c 100644
--- a/scripts/build.ts
+++ b/scripts/build.ts
@@ -29,7 +29,8 @@ const featureFlags: Record<string, boolean> = {
   ABLATION_BASELINE: false,
   DUMP_SYSTEM_PROMPT: false,
   CACHED_MICROCOMPACT: false,
-  COORDINATOR_MODE: false,
+  COORDINATOR_MODE: true,
+  BUILTIN_EXPLORE_PLAN_AGENTS: true,
   CONTEXT_COLLAPSE: false,
   COMMIT_ATTRIBUTION: false,
   TEAMMEM: false,
diff --git a/src/coordinator/workerAgent.ts b/src/coordinator/workerAgent.ts
new file mode 100644
index 00000000..8e65cf9c
--- /dev/null
+++ b/src/coordinator/workerAgent.ts
@@ -0,0 +1,18 @@
+import type { BuiltInAgentDefinition } from '../tools/AgentTool/loadAgentsDir.js'
+import { EXPLORE_AGENT } from '../tools/AgentTool/built-in/exploreAgent.js'
+import { GENERAL_PURPOSE_AGENT } from '../tools/AgentTool/built-in/generalPurposeAgent.js'
+import { PLAN_AGENT } from '../tools/AgentTool/built-in/planAgent.js'
+
+// The coordinator system prompt instructs the model to spawn workers with
+// subagent_type: "worker". This agent definition matches that type so
+// AgentTool.tsx can resolve it. It reuses GENERAL_PURPOSE_AGENT's capabilities.
+const WORKER_AGENT: BuiltInAgentDefinition = {
+  ...GENERAL_PURPOSE_AGENT,
+  agentType: 'worker',
+  whenToUse:
+    'Worker agent for coordinator mode. Executes tasks autonomously — research, implementation, or verification.',
+}
+
+export function getCoordinatorAgents(): BuiltInAgentDefinition[] {
+  return [WORKER_AGENT, GENERAL_PURPOSE_AGENT, EXPLORE_AGENT, PLAN_AGENT]
+}