Function createFileOnBranch

src/utils/github.ts:270–333

(
  token: string,
  owner: string,
  repo: string,
  branch: string,
  filePath: string,
  content: string,
  message: string
)

 * Commit a single file to a branch using the low-level Git Data API.
 */
export async function createFileOnBranch(
  token: string,
  owner: string,
  repo: string,
  branch: string,
  filePath: string,
  content: string,
  message: string
) {
  const base = `/repos/${owner}/${repo}`;
  const jsonHeaders = { 'Content-Type': 'application/json' };

  // Step 1: Get the current commit SHA
  const refRes = await ghFetch(`${base}/git/ref/heads/${encodeURIComponent(branch)}`, token);
  if (!refRes.ok) await handleGitError(refRes, 'Failed to get branch ref');
  const refData = await refRes.json();
  const latestCommitSHA: string = refData.object.sha;

  // Step 2: Get the tree SHA
  const commitRes = await ghFetch(`${base}/git/commits/${latestCommitSHA}`, token);
  if (!commitRes.ok) await handleGitError(commitRes, 'Failed to get commit');
  const commitData = await commitRes.json();
  const baseTreeSHA: string = commitData.tree.sha;

  // Step 3: Create a blob
  const base64Content = utf8ToBase64(content);
  const blobRes = await ghFetch(`${base}/git/blobs`, token, {
    method: 'POST',
    body: JSON.stringify({ content: base64Content, encoding: 'base64' }),
    headers: jsonHeaders,
  });
  if (!blobRes.ok) await handleGitError(blobRes, 'Failed to create blob');
  const blobData = await blobRes.json();

  // Step 4: Create a new tree
  const treeRes = await ghFetch(`${base}/git/trees`, token, {
    method: 'POST',
    body: JSON.stringify({
      base_tree: baseTreeSHA,
      tree: [{ path: filePath, mode: '100644', type: 'blob', sha: blobData.sha }],
    }),
    headers: jsonHeaders,
  });
  if (!treeRes.ok) await handleGitError(treeRes, 'Failed to create tree');
  const treeData = await treeRes.json();

  // Step 5: Create a new commit
  const newCommitRes = await ghFetch(`${base}/git/commits`, token, {
    method: 'POST',
    body: JSON.stringify({ message, tree: treeData.sha, parents: [latestCommitSHA] }),
    headers: jsonHeaders,
  });
  if (!newCommitRes.ok) await handleGitError(newCommitRes, 'Failed to create commit');
  const newCommitData = await newCommitRes.json();

  // Step 6: Update the branch ref (force: true to avoid "not a fast forward" errors)
  const updateRefRes = await ghFetch(`${base}/git/refs/heads/${encodeURIComponent(branch)}`, token, {
    method: 'PATCH',