Refactor mergePullRequest to use GraphQL for auto-merge functionality

Author: DaleSeo

handlers/merge_prs.js

@@ -150,32 +150,90 @@ export async function mergePrs(request, env) {
 }
 
 async function mergePullRequest(owner, repo, prNumber, mergeMethod, token, sha) {
-  const response = await fetch(
-    `https://api.github.com/repos/${owner}/${repo}/pulls/${prNumber}/merge`,
-    {
-      method: "PUT",
-      headers: {
-        ...getGitHubHeaders(token),
-        "Content-Type": "application/json",
-      },
-      body: JSON.stringify({
-        merge_method: mergeMethod,
-        sha,
-      }),
+  // 1. PR의 GraphQL node ID 조회
+  const nodeId = await getPullRequestNodeId(owner, repo, prNumber, token);
+  if (!nodeId) {
+    return {
+      merged: false,
+      error: "Failed to get PR node ID",
+    };
+  }
+
+  // 2. Merge method 매핑 (REST → GraphQL)
+  const graphqlMergeMethod = {
+    merge: "MERGE",
+    squash: "SQUASH",
+    rebase: "REBASE",
+  }[mergeMethod] || "MERGE";
+
+  // 3. Auto-merge 활성화 (Merge Queue 사용)
+  const mutation = `
+    mutation {
+      enablePullRequestAutoMerge(input: {
+        pullRequestId: "${nodeId}"
+        mergeMethod: ${graphqlMergeMethod}
+      }) {
+        pullRequest {
+          id
+          number
+          autoMergeRequest {
+            enabledAt
+            mergeMethod
+          }
+        }
+      }
     }
-  );
+  `;
+
+  const response = await fetch("https://api.github.com/graphql", {
+    method: "POST",
+    headers: {
+      ...getGitHubHeaders(token),
+      "Content-Type": "application/json",
+    },
+    body: JSON.stringify({ query: mutation }),
+  });
+
+  const result = await safeJson(response);
 
-  const payload = await safeJson(response);
-  if (response.ok && payload?.merged) {
-    return { merged: true, sha: payload.sha };
+  if (response.ok && result.data?.enablePullRequestAutoMerge?.pullRequest) {
+    return {
+      merged: true,
+      autoMergeEnabled: true,
+      sha: sha,
+    };
   }
 
   return {
     merged: false,
-    error: payload?.message || "Merge failed",
+    error: result.errors?.[0]?.message || "Auto-merge failed",
   };
 }
 
+async function getPullRequestNodeId(owner, repo, prNumber, token) {
+  const query = `
+    query {
+      repository(owner: "${owner}", name: "${repo}") {
+        pullRequest(number: ${prNumber}) {
+          id
+        }
+      }
+    }
+  `;
+
+  const response = await fetch("https://api.github.com/graphql", {
+    method: "POST",
+    headers: {
+      ...getGitHubHeaders(token),
+      "Content-Type": "application/json",
+    },
+    body: JSON.stringify({ query }),
+  });
+
+  const result = await safeJson(response);
+  return result.data?.repository?.pullRequest?.id || null;
+}
+
 async function getMergeableState(owner, repo, prNumber, token) {
   const prDetails = await getPullRequestDetails(owner, repo, prNumber, token);