diff --git a/src/git/apiHandler.js b/src/git/apiHandler.js
index e2ab8c6..0ef827a 100644
--- a/src/git/apiHandler.js
+++ b/src/git/apiHandler.js
@@ -135,6 +135,28 @@ async function createRepoGitHub({
   if (license) {
     body.license_template = license;
   }
+
+  const githubErrorsToText = (errors) => {
+    if (!Array.isArray(errors) || errors.length === 0) return '';
+    return errors
+      .map(err => {
+        if (!err) return '';
+        if (typeof err === 'string') return err;
+        const field = err.field ? `${err.field}: ` : '';
+        const message = err.message || err.code || '';
+        return `${field}${message}`.trim();
+      })
+      .filter(Boolean)
+      .join('; ');
+  };
+
+  const isGithubRepoAlreadyExists = (msg, errors) => {
+    const text = `${String(msg || '')} ${githubErrorsToText(errors)}`.toLowerCase();
+    if (text.includes('already exists')) return true;
+    if (text.includes('already_exists')) return true;
+    if (text.includes('name already exists')) return true;
+    return false;
+  };
   
   try {
     const response = await axiosInstance.post('https://api.github.com/user/repos', body, {
@@ -151,10 +173,11 @@ async function createRepoGitHub({
         throw new Error('Authentifizierung fehlgeschlagen. Bitte überprüfen Sie Ihren GitHub-Token.');
       } else if (status === 422) {
         const msg = data?.message || 'Repository konnte nicht erstellt werden';
-        if (msg.includes('name already exists')) {
+        const details = githubErrorsToText(data?.errors);
+        if (isGithubRepoAlreadyExists(msg, data?.errors)) {
           throw new Error(`Ein Repository mit dem Namen "${name}" existiert bereits.`);
         }
-        throw new Error(`GitHub-Fehler: ${msg}`);
+        throw new Error(`GitHub-Fehler: ${msg}${details ? ` (${details})` : ''}`);
       } else if (status === 403) {
         throw new Error('Zugriff verweigert. Bitte überprüfen Sie Ihre Token-Berechtigungen.');
       } else {
@@ -1336,6 +1359,22 @@ async function getGithubCurrentUser({ token }) {
   return response.data;
 }
 
+async function githubRepoExists({ token, owner, repo }) {
+  if (!token) throw new Error('GitHub Token fehlt.');
+  if (!owner || !repo) throw new Error('Owner oder Repository fehlt.');
+
+  try {
+    await axiosInstance.get(`${GITHUB_API}/repos/${encodeURIComponent(owner)}/${encodeURIComponent(repo)}`, {
+      headers: githubHeaders(token),
+      timeout: 12000
+    });
+    return true;
+  } catch (error) {
+    if (error?.response?.status === 404) return false;
+    throw error;
+  }
+}
+
 async function getGithubUserHeatmap({ token, monthsBack = 20 }) {
   if (!token) throw new Error('GitHub Token fehlt.');
 
@@ -1870,6 +1909,16 @@ async function updateGithubRepoVisibility({ token, owner, repo, isPrivate }) {
   return response.data;
 }
 
+async function updateGithubRepoDefaultBranch({ token, owner, repo, defaultBranch }) {
+  if (!defaultBranch) throw new Error('Default-Branch fehlt.');
+  const response = await axiosInstance.patch(
+    `${GITHUB_API}/repos/${encodeURIComponent(owner)}/${encodeURIComponent(repo)}`,
+    { default_branch: String(defaultBranch).trim() },
+    { headers: githubHeaders(token), timeout: 15000 }
+  );
+  return response.data;
+}
+
 async function updateGithubRepoTopics({ token, owner, repo, topics }) {
   const response = await axiosInstance.put(
     `${GITHUB_API}/repos/${encodeURIComponent(owner)}/${encodeURIComponent(repo)}/topics`,
@@ -1947,6 +1996,7 @@ module.exports = {
   // GitHub API
   listGithubRepos,
   getGithubCurrentUser,
+  githubRepoExists,
   getGithubUserHeatmap,
   getGithubRepoContents,
   getGithubFileContent,
@@ -1962,6 +2012,7 @@ module.exports = {
   editGithubRelease,
   deleteGithubRelease,
   updateGithubRepoVisibility,
+  updateGithubRepoDefaultBranch,
   updateGithubRepoTopics,
   deleteGithubRepo
 };
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