Fix: Add git authentication to agent mode

Agent mode now fetches the authenticated user (claude[bot] when using Claude App token)
and configures git identity properly, matching the behavior of tag mode.

This fixes the issue where commits in agent mode were failing due to missing git identity.

src/modes/agent/index.ts

@@ -4,6 +4,7 @@ import type { Mode, ModeOptions, ModeResult } from "../types";
 import type { PreparedContext } from "../../create-prompt/types";
 import { prepareMcpConfig } from "../../mcp/install-mcp-server";
 import { parseAllowedTools } from "./parse-tools";
+import { configureGitAuth } from "../../github/operations/git-config";
 
 /**
  * Agent mode implementation.
@@ -41,7 +42,26 @@ export const agentMode: Mode = {
     return false;
   },
 
-  async prepare({ context, githubToken }: ModeOptions): Promise<ModeResult> {
+  async prepare({ context, githubToken, octokit }: ModeOptions): Promise<ModeResult> {
+    // Configure git authentication for agent mode (same as tag mode)
+    // Fetch the authenticated user to set proper git identity
+    if (!context.inputs.useCommitSigning) {
+      try {
+        // Get the authenticated user (will be claude[bot] when using Claude App token)
+        const { data: authenticatedUser } = await octokit.rest.users.getAuthenticated();
+        const user = {
+          login: authenticatedUser.login,
+          id: authenticatedUser.id,
+        };
+        
+        // Configure git with the authenticated user's identity
+        await configureGitAuth(githubToken, context, user);
+      } catch (error) {
+        console.error("Failed to configure git authentication:", error);
+        // Continue anyway - git operations may still work with default config
+      }
+    }
+
     // Create prompt directory
     await mkdir(`${process.env.RUNNER_TEMP || "/tmp"}/claude-prompts`, {
       recursive: true,