diff --git a/src/tools/AgentTool/builtInAgents.test.ts b/src/tools/AgentTool/builtInAgents.test.ts
new file mode 100644
index 00000000..35ebd98c
--- /dev/null
+++ b/src/tools/AgentTool/builtInAgents.test.ts
@@ -0,0 +1,50 @@
+import { afterEach, describe, expect, test } from 'bun:test'
+import {
+  setIsInteractive,
+} from '../../bootstrap/state.js'
+import {
+  areExplorePlanAgentsEnabled,
+  getBuiltInAgents,
+} from './builtInAgents.js'
+
+const originalDisableBuiltIns =
+  process.env.CLAUDE_AGENT_SDK_DISABLE_BUILTIN_AGENTS
+const originalEntrypoint = process.env.CLAUDE_CODE_ENTRYPOINT
+
+afterEach(() => {
+  if (originalDisableBuiltIns === undefined) {
+    delete process.env.CLAUDE_AGENT_SDK_DISABLE_BUILTIN_AGENTS
+  } else {
+    process.env.CLAUDE_AGENT_SDK_DISABLE_BUILTIN_AGENTS =
+      originalDisableBuiltIns
+  }
+
+  if (originalEntrypoint === undefined) {
+    delete process.env.CLAUDE_CODE_ENTRYPOINT
+  } else {
+    process.env.CLAUDE_CODE_ENTRYPOINT = originalEntrypoint
+  }
+
+  setIsInteractive(false)
+})
+
+describe('built-in agents', () => {
+  test('enables public built-in agents in external builds', () => {
+    setIsInteractive(true)
+
+    expect(areExplorePlanAgentsEnabled()).toBe(true)
+
+    const agentTypes = getBuiltInAgents().map(agent => agent.agentType)
+
+    expect(agentTypes).toContain('Explore')
+    expect(agentTypes).toContain('Plan')
+    expect(agentTypes).toContain('verification')
+  })
+
+  test('preserves SDK opt-out in noninteractive sessions', () => {
+    setIsInteractive(false)
+    process.env.CLAUDE_AGENT_SDK_DISABLE_BUILTIN_AGENTS = 'true'
+
+    expect(getBuiltInAgents()).toEqual([])
+  })
+})
diff --git a/src/tools/AgentTool/builtInAgents.ts b/src/tools/AgentTool/builtInAgents.ts
index 721dff96..9d2eb66e 100644
--- a/src/tools/AgentTool/builtInAgents.ts
+++ b/src/tools/AgentTool/builtInAgents.ts
@@ -11,14 +11,27 @@ import { VERIFICATION_AGENT } from './built-in/verificationAgent.js'
 import type { AgentDefinition } from './loadAgentsDir.js'
 
 export function areExplorePlanAgentsEnabled(): boolean {
+  if (process.env.USER_TYPE !== 'ant') {
+    return true
+  }
+
   if (feature('BUILTIN_EXPLORE_PLAN_AGENTS')) {
-    // 3P default: true — Bedrock/Vertex keep agents enabled (matches pre-experiment
-    // external behavior). A/B test treatment sets false to measure impact of removal.
     return getFeatureValue_CACHED_MAY_BE_STALE('tengu_amber_stoat', true)
   }
   return false
 }
 
+function isVerificationAgentEnabled(): boolean {
+  if (process.env.USER_TYPE !== 'ant') {
+    return true
+  }
+
+  if (feature('VERIFICATION_AGENT')) {
+    return getFeatureValue_CACHED_MAY_BE_STALE('tengu_hive_evidence', false)
+  }
+  return false
+}
+
 export function getBuiltInAgents(): AgentDefinition[] {
   // Allow disabling all built-in agents via env var (useful for SDK users who want a blank slate)
   // Only applies in noninteractive mode (SDK/API usage)
@@ -61,10 +74,7 @@ export function getBuiltInAgents(): AgentDefinition[] {
     agents.push(CLAUDE_CODE_GUIDE_AGENT)
   }
 
-  if (
-    feature('VERIFICATION_AGENT') &&
-    getFeatureValue_CACHED_MAY_BE_STALE('tengu_hive_evidence', false)
-  ) {
+  if (isVerificationAgentEnabled()) {
     agents.push(VERIFICATION_AGENT)
   }