diff --git a/action.yml b/action.yml
index 1a0d1a0..005f0e7 100644
--- a/action.yml
+++ b/action.yml
@@ -42,7 +42,10 @@ inputs:
 
   # Auth configuration
   anthropic_api_key:
-    description: "Anthropic API key (required for direct API, not needed for Bedrock/Vertex)"
+    description: "Anthropic API key (required for direct API, not needed for Bedrock/Vertex). Set to 'use-oauth' when using claude_credentials"
+    required: false
+  claude_credentials:
+    description: "Claude OAuth credentials JSON for Claude AI Max subscription authentication"
     required: false
   gitea_token:
     description: "Gitea token with repo and pull request permissions (defaults to GITHUB_TOKEN)"
@@ -96,6 +99,8 @@ runs:
         GITHUB_TOKEN: ${{ github.token }}
         GITHUB_RUN_ID: ${{ github.run_id }}
         GITEA_API_URL: ${{ env.GITHUB_SERVER_URL }}
+        ANTHROPIC_API_KEY: ${{ inputs.anthropic_api_key }}
+        CLAUDE_CREDENTIALS: ${{ inputs.claude_credentials }}
 
     - name: Run Claude Code
       id: claude-code
@@ -123,6 +128,7 @@ runs:
         USE_BEDROCK: ${{ inputs.use_bedrock }}
         USE_VERTEX: ${{ inputs.use_vertex }}
         ANTHROPIC_API_KEY: ${{ inputs.anthropic_api_key }}
+        CLAUDE_CREDENTIALS: ${{ inputs.claude_credentials }}
 
         # GitHub token for repository access
         GITHUB_TOKEN: ${{ steps.prepare.outputs.GITHUB_TOKEN }}
diff --git a/src/claude/oauth-setup.ts b/src/claude/oauth-setup.ts
new file mode 100644
index 0000000..f9d3a41
--- /dev/null
+++ b/src/claude/oauth-setup.ts
@@ -0,0 +1,59 @@
+import { mkdir, writeFile } from "fs/promises";
+import { join } from "path";
+import { homedir } from "os";
+
+interface OAuthCredentials {
+  accessToken: string;
+  refreshToken: string;
+  expiresAt: string;
+}
+
+interface ClaudeCredentialsInput {
+  claudeAiOauth: {
+    accessToken: string;
+    refreshToken: string;
+    expiresAt: number;
+    scopes: string[];
+  };
+}
+
+export async function setupOAuthCredentials(credentialsJson: string) {
+  try {
+    // Parse the credentials JSON
+    const parsedCredentials: ClaudeCredentialsInput = JSON.parse(credentialsJson);
+    
+    if (!parsedCredentials.claudeAiOauth) {
+      throw new Error("Invalid credentials format: missing claudeAiOauth");
+    }
+
+    const { accessToken, refreshToken, expiresAt } = parsedCredentials.claudeAiOauth;
+    
+    if (!accessToken || !refreshToken || !expiresAt) {
+      throw new Error("Invalid credentials format: missing required OAuth fields");
+    }
+
+    const claudeDir = join(homedir(), ".claude");
+    const credentialsPath = join(claudeDir, ".credentials.json");
+
+    // Create the .claude directory if it doesn't exist
+    await mkdir(claudeDir, { recursive: true });
+
+    // Create the credentials JSON structure
+    const credentialsData = {
+      claudeAiOauth: {
+        accessToken,
+        refreshToken,
+        expiresAt,
+        scopes: ["user:inference", "user:profile"],
+      },
+    };
+
+    // Write the credentials file
+    await writeFile(credentialsPath, JSON.stringify(credentialsData, null, 2));
+
+    console.log(`OAuth credentials written to ${credentialsPath}`);
+  } catch (error) {
+    const errorMessage = error instanceof Error ? error.message : String(error);
+    throw new Error(`Failed to setup OAuth credentials: ${errorMessage}`);
+  }
+}
\ No newline at end of file
diff --git a/src/entrypoints/prepare.ts b/src/entrypoints/prepare.ts
index 2f3ec12..5b0d497 100644
--- a/src/entrypoints/prepare.ts
+++ b/src/entrypoints/prepare.ts
@@ -18,17 +18,27 @@ import { createPrompt } from "../create-prompt";
 import { createClient } from "../github/api/client";
 import { fetchGitHubData } from "../github/data/fetcher";
 import { parseGitHubContext } from "../github/context";
+import { setupOAuthCredentials } from "../claude/oauth-setup";
 
 async function run() {
   try {
-    // Step 1: Setup GitHub token
+    // Step 1: Setup OAuth credentials if provided
+    const claudeCredentials = process.env.CLAUDE_CREDENTIALS;
+    const anthropicApiKey = process.env.ANTHROPIC_API_KEY;
+    
+    if (claudeCredentials && anthropicApiKey === "use-oauth") {
+      await setupOAuthCredentials(claudeCredentials);
+      console.log("OAuth credentials configured for Claude AI Max subscription");
+    }
+
+    // Step 2: Setup GitHub token
     const githubToken = await setupGitHubToken();
     const client = createClient(githubToken);
 
-    // Step 2: Parse GitHub context (once for all operations)
+    // Step 3: Parse GitHub context (once for all operations)
     const context = parseGitHubContext();
 
-    // Step 3: Check write permissions
+    // Step 4: Check write permissions
     const hasWritePermissions = await checkWritePermissions(
       client.api,
       context,
@@ -39,7 +49,7 @@ async function run() {
       );
     }
 
-    // Step 4: Check trigger conditions
+    // Step 5: Check trigger conditions
     const containsTrigger = await checkTriggerAction(context);
 
     // Set outputs that are always needed
@@ -51,14 +61,14 @@ async function run() {
       return;
     }
 
-    // Step 5: Check if actor is human
+    // Step 6: Check if actor is human
     await checkHumanActor(client.api, context);
 
-    // Step 6: Create initial tracking comment
+    // Step 7: Create initial tracking comment
     const commentId = await createInitialComment(client.api, context);
     core.setOutput("claude_comment_id", commentId.toString());
 
-    // Step 7: Fetch GitHub data (once for both branch setup and prompt creation)
+    // Step 8: Fetch GitHub data (once for both branch setup and prompt creation)
     const githubData = await fetchGitHubData({
       client: client,
       repository: `${context.repository.owner}/${context.repository.repo}`,
@@ -66,14 +76,14 @@ async function run() {
       isPR: context.isPR,
     });
 
-    // Step 8: Setup branch
+    // Step 9: Setup branch
     const branchInfo = await setupBranch(client, githubData, context);
     core.setOutput("BASE_BRANCH", branchInfo.baseBranch);
     if (branchInfo.claudeBranch) {
       core.setOutput("CLAUDE_BRANCH", branchInfo.claudeBranch);
     }
 
-    // Step 9: Update initial comment with branch link (only if a claude branch was created)
+    // Step 10: Update initial comment with branch link (only if a claude branch was created)
     if (branchInfo.claudeBranch) {
       await updateTrackingComment(
         client,
@@ -83,7 +93,7 @@ async function run() {
       );
     }
 
-    // Step 10: Create prompt file
+    // Step 11: Create prompt file
     await createPrompt(
       commentId,
       branchInfo.baseBranch,
@@ -92,7 +102,7 @@ async function run() {
       context,
     );
 
-    // Step 11: Get MCP configuration
+    // Step 12: Get MCP configuration
     const mcpConfig = await prepareMcpConfig(
       githubToken,
       context.repository.owner,