Fix Mastodon import for archives with nested root folder

[obenland]

Fixes https://wordpress.org/support/topic/import-mastodon-beta/page/2/#post-18741275

Proposed changes:

• Handle Mastodon archive exports that wrap all files in a root folder (e.g., archive-name/outbox.json instead of outbox.json at root level).
• Use $wp_filesystem->exists() instead of dirlist() for checking outbox.json existence (more efficient).
• Use $wp_filesystem->get_contents() instead of file_get_contents() for consistency with the rest of the codebase and to remove phpcs ignore comment.

Other information:

• Have you written new tests for your changes, if applicable?

Testing instructions:

1. Export your archive from Mastodon (Preferences > Import and Export > Request your archive).
2. Go to Tools > Import > Mastodon.
3. Upload a Mastodon archive ZIP that has files nested in a root folder.
4. Verify the import proceeds without "The archive does not contain an Outbox file" error.

Changelog entry

• Automatically create a changelog entry from the details below.

Changelog Entry Details

Significance

• Patch
• Minor
• Major

Type

• Added - for new features
• Changed - for changes in existing functionality
• Deprecated - for soon-to-be removed features
• Removed - for now removed features
• Fixed - for any bug fixes
• Security - in case of vulnerabilities

Message

Fix Mastodon import for archives with nested root folder.

[Copilot]

Pull request overview

This PR fixes an issue where Mastodon archive imports fail when the archive contains a nested root folder structure. The fix detects and handles archives where files are wrapped in a single root directory (e.g., archive-name/outbox.json) instead of being at the root level.

Key Changes:

• Added maybe_unwrap_archive() method to detect and handle nested archive structures
• Replaced dirlist() check with $wp_filesystem->exists() for better performance
• Replaced file_get_contents() with $wp_filesystem->get_contents() for consistency

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
includes/wp-admin/import/class-mastodon.php	Added archive unwrapping logic and improved file system operations for consistency
.github/changelog/2581-from-description	Added changelog entry documenting the bug fix

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[pfefferle]

Is it possible to somehow test this with a unittest?

[obenland]

Is it possible to somehow test this with a unittest?

It is! Fixed in b17eede.