fix: resolve the checkout root correctly inside a git worktree

packages/core/src/-private/repo-info.ts

@@ -1,7 +1,41 @@
+import fs from 'fs';
 import path from 'path';
 import getRepoInfo from 'git-repo-info';
 import GitHost from 'hosted-git-info';
 
+/**
+ * Resolves the top level of the checkout that `target` lives in.
+ *
+ * `git-repo-info` documents that its `root` points at the original copy rather
+ * than the worktree when called from inside a linked worktree. Using it
+ * directly makes the relative path below include the worktree's own location,
+ * producing edit URLs for paths that do not exist on the remote.
+ *
+ * A worktree's metadata directory holds a `gitdir` file pointing at that
+ * worktree's `.git` file, and its parent is the top level we want. Outside a
+ * worktree `worktreeGitDir` and `commonGitDir` are the same, so there is
+ * nothing to correct.
+ */
+function getCheckoutRoot(target: string): string {
+  const { root, commonGitDir, worktreeGitDir } = getRepoInfo(target);
+
+  if (!worktreeGitDir || worktreeGitDir === commonGitDir) {
+    return root;
+  }
+
+  try {
+    const gitdir = fs.readFileSync(path.join(worktreeGitDir, 'gitdir'), 'utf8').trim();
+
+    if (gitdir) {
+      return path.dirname(gitdir);
+    }
+  } catch {
+    // No readable `gitdir` pointer, so fall back to the reported root.
+  }
+
+  return root;
+}
+
 // A whitelist, not a fallback: `getTreePath` only knows two URL shapes, Bitbucket's
 // and the `/edit/` form GitHub and GitLab accept. Every other host hosted-git-info can
 // parse (gist, sourcehut, anything a future release adds) would otherwise be handed a
@@ -30,7 +64,7 @@ export function getRepoEditUrl(root: string, repoURL: string, branch = 'master')
   let result: string | null = null;
 
   try {
-    const gitRoot = getRepoInfo(root).root;
+    const gitRoot = getCheckoutRoot(root);
     const repo = GitHost.fromUrl(repoURL);
     const relative = path.relative(gitRoot, root);
     const tree = getTreePath(repo, branch, relative);

packages/core/tests/repo-info-worktree.test.ts

@@ -0,0 +1,51 @@
+import fs from 'fs';
+import os from 'os';
+import path from 'path';
+import { execFileSync } from 'child_process';
+import { getRepoEditUrl } from '../src/-private/repo-info.js';
+
+/**
+ * `git-repo-info` reports the *original* checkout's root when called from
+ * inside a linked worktree, which used to leak the worktree's own location into
+ * every edit URL. CI runs in a normal checkout, so without this test that
+ * regression would be invisible there.
+ */
+describe('getRepoEditUrl in a git worktree', () => {
+  // realpath matters: on macOS os.tmpdir() is a symlink and git records the
+  // resolved path, so comparing against the unresolved one would break.
+  const tmp = fs.realpathSync(fs.mkdtempSync(path.join(os.tmpdir(), 'docfy-worktree-')));
+  const mainCheckout = path.join(tmp, 'main');
+  const worktree = path.join(tmp, 'linked');
+  const expected = 'https://github.com/user/repo/edit/main/docs/{filepath}';
+
+  beforeAll(() => {
+    const git = (...args: string[]): void => {
+      execFileSync('git', args, { cwd: mainCheckout, stdio: 'pipe' });
+    };
+
+    fs.mkdirSync(path.join(mainCheckout, 'docs'), { recursive: true });
+    git('init', '-b', 'main');
+    git('config', 'user.email', 'test@example.com');
+    git('config', 'user.name', 'Docfy Test');
+    fs.writeFileSync(path.join(mainCheckout, 'docs', 'index.md'), '# Hello\n');
+    git('add', '.');
+    git('commit', '-m', 'init');
+    git('worktree', 'add', worktree, '-b', 'feature');
+  });
+
+  afterAll(() => {
+    fs.rmSync(tmp, { recursive: true, force: true });
+  });
+
+  test('the edit url does not include the worktree location', () => {
+    expect(
+      getRepoEditUrl(path.join(worktree, 'docs'), 'https://github.com/user/repo', 'main')
+    ).toBe(expected);
+  });
+
+  test('the same source path resolves identically in the main checkout', () => {
+    expect(
+      getRepoEditUrl(path.join(mainCheckout, 'docs'), 'https://github.com/user/repo', 'main')
+    ).toBe(expected);
+  });
+});