diff --git a/src/github/validation/actor.ts b/src/github/validation/actor.ts
index 2599254..36be2ff 100644
--- a/src/github/validation/actor.ts
+++ b/src/github/validation/actor.ts
@@ -6,11 +6,11 @@
  */
 
 import type { Octokit } from "@octokit/rest";
-import type { ParsedGitHubContext } from "../context";
+import type { GitHubContext } from "../context";
 
 export async function checkHumanActor(
   octokit: Octokit,
-  githubContext: ParsedGitHubContext,
+  githubContext: GitHubContext,
 ) {
   // Fetch user information from GitHub API
   const { data: userData } = await octokit.users.getByUsername({
diff --git a/src/modes/agent/index.ts b/src/modes/agent/index.ts
index 1b992a7..59b78b4 100644
--- a/src/modes/agent/index.ts
+++ b/src/modes/agent/index.ts
@@ -8,6 +8,7 @@ import {
   configureGitAuth,
   setupSshSigning,
 } from "../../github/operations/git-config";
+import { checkHumanActor } from "../../github/validation/actor";
 import type { GitHubContext } from "../../github/context";
 import { isEntityContext } from "../../github/context";
 
@@ -80,7 +81,14 @@ export const agentMode: Mode = {
     return false;
   },
 
-  async prepare({ context, githubToken }: ModeOptions): Promise<ModeResult> {
+  async prepare({
+    context,
+    octokit,
+    githubToken,
+  }: ModeOptions): Promise<ModeResult> {
+    // Check if actor is human (prevents bot-triggered loops)
+    await checkHumanActor(octokit.rest, context);
+
     // Configure git authentication for agent mode (same as tag mode)
     // SSH signing takes precedence if provided
     const useSshSigning = !!context.inputs.sshSigningKey;
diff --git a/test/modes/agent.test.ts b/test/modes/agent.test.ts
index 16e3796..25bf844 100644
--- a/test/modes/agent.test.ts
+++ b/test/modes/agent.test.ts
@@ -145,12 +145,12 @@ describe("Agent Mode", () => {
         users: {
           getAuthenticated: mock(() =>
             Promise.resolve({
-              data: { login: "test-user", id: 12345 },
+              data: { login: "test-user", id: 12345, type: "User" },
             }),
           ),
           getByUsername: mock(() =>
             Promise.resolve({
-              data: { login: "test-user", id: 12345 },
+              data: { login: "test-user", id: 12345, type: "User" },
             }),
           ),
         },
@@ -187,6 +187,65 @@ describe("Agent Mode", () => {
       process.env.GITHUB_REF_NAME = originalRefName;
   });
 
+  test("prepare method rejects bot actors without allowed_bots", async () => {
+    const contextWithPrompts = createMockAutomationContext({
+      eventName: "workflow_dispatch",
+    });
+    contextWithPrompts.actor = "claude[bot]";
+    contextWithPrompts.inputs.allowedBots = "";
+
+    const mockOctokit = {
+      rest: {
+        users: {
+          getByUsername: mock(() =>
+            Promise.resolve({
+              data: { login: "claude[bot]", id: 12345, type: "Bot" },
+            }),
+          ),
+        },
+      },
+    } as any;
+
+    await expect(
+      agentMode.prepare({
+        context: contextWithPrompts,
+        octokit: mockOctokit,
+        githubToken: "test-token",
+      }),
+    ).rejects.toThrow(
+      "Workflow initiated by non-human actor: claude (type: Bot)",
+    );
+  });
+
+  test("prepare method allows bot actors when in allowed_bots list", async () => {
+    const contextWithPrompts = createMockAutomationContext({
+      eventName: "workflow_dispatch",
+    });
+    contextWithPrompts.actor = "dependabot[bot]";
+    contextWithPrompts.inputs.allowedBots = "dependabot";
+
+    const mockOctokit = {
+      rest: {
+        users: {
+          getByUsername: mock(() =>
+            Promise.resolve({
+              data: { login: "dependabot[bot]", id: 12345, type: "Bot" },
+            }),
+          ),
+        },
+      },
+    } as any;
+
+    // Should not throw - bot is in allowed list
+    await expect(
+      agentMode.prepare({
+        context: contextWithPrompts,
+        octokit: mockOctokit,
+        githubToken: "test-token",
+      }),
+    ).resolves.toBeDefined();
+  });
+
   test("prepare method creates prompt file with correct content", async () => {
     const contextWithPrompts = createMockAutomationContext({
       eventName: "workflow_dispatch",
@@ -199,12 +258,12 @@ describe("Agent Mode", () => {
         users: {
           getAuthenticated: mock(() =>
             Promise.resolve({
-              data: { login: "test-user", id: 12345 },
+              data: { login: "test-user", id: 12345, type: "User" },
             }),
           ),
           getByUsername: mock(() =>
             Promise.resolve({
-              data: { login: "test-user", id: 12345 },
+              data: { login: "test-user", id: 12345, type: "User" },
             }),
           ),
         },