feat(folders): create a new folder while picking one to open

[Jonathan-Asher]

Summary

Adds New folder to the directory browser of the Open Folder dialog, so a project can start from an empty folder without leaving codeg: name the folder, and the browser moves into it, ready for Next. It works the same in the desktop app and in server/web mode, since the browser lists the filesystem of whichever host serves the workspace. The desktop app's native folder picker now also asks the macOS panel for its own New Folder button.

Behavior

• Browser.
  • A folder-plus button sits beside Home and Up at the start of the path box. It opens a name box at the top of the listing, with a line underneath naming the directory the folder will go in.
  • Enter or the check button creates the folder in the directory being listed. The browser then moves into it, so the path box holds the new folder and Next opens it as the workspace. Creating does not open anything by itself.
  • Escape or the X cancels and leaves the dialog open. The dialog dismisses on Escape from a capture listener on document, which runs before any handler on the input, so the browser claims Escape on window while the name box has focus.
  • A rejected name is explained under the box, which keeps what was typed. Editing the name clears the message. Navigating to another directory closes a half-typed box. While the request runs, the dialog's Next button is disabled.
  • After a folder is created, cached listings are dropped, so going back up shows the new folder.
  • DirectoryBrowser gets an opt-in allowCreateFolder prop. Only the Open Folder dialog's first step turns it on. Its link-targets step and the other pickers that embed the browser (clone destination, worktree path, project boot) are unchanged.
• Endpoint. create_directory(parentPath, name) is a Tauri command and POST /api/create_directory. Both call create_directory_core, which returns the new folder's path: the parent as given, joined with the name.
• Validation (CreateDirectoryError, a thiserror enum):
  • The name is trimmed. On every platform it is rejected if it is empty, . or .., or contains /, \, NUL or any other control character. On Windows it is also rejected if it contains < > : " | ? *, ends with a dot (Windows strips a trailing dot without saying so), or is a device name such as CON or nul.txt.
  • The parent must be an absolute path to an existing directory. A symlink to a directory is followed, as the browser follows one when it lists it.
  • Exactly one directory is created (create_dir, never create_dir_all). A missing parent is an error, and nothing above the new folder is created.
  • If an entry of that name already exists (a file, a directory, or a symlink, dangling or not), the request fails with "already exists". The entry is never reused and a symlink is never followed. create_dir also refuses an existing path, so a name taken between the check and the creation gets the same error.
  • Errors map onto the existing codes: invalid name or parent 400, missing parent 404, already exists 409, permission denied 403, any other I/O error 500. Each also carries an i18n key under DirectoryBrowser.newFolder.errors, and the browser renders it with toLocalizedErrorMessage. The new strings are translated in all ten locales.
• Native picker. openFileDialog passes canCreateDirectories: true for directory picks. tauri-plugin-dialog 2.6 already defaults this to true on macOS, so the call keeps current behavior in place rather than changing it. The Windows and Linux folder dialogs have a new-folder button of their own.
• Not included.
  • The directory browser has no root or allow-list in server mode. Like list_directory_entries, the endpoint can reach whatever the server process can, and it adds no restriction of its own.
  • No "git init" option. A folder opened without a repository already offers "Initialize Git repository" from the branch chip.

Verification

• Rust unit tests in commands::create_directory:
  • creating a folder, and the path returned;
  • trimming, and Unicode names;
  • an existing directory, an existing file, and a live or dangling symlink under that name;
  • empty names, ., .., and NUL and other control characters;
  • traversal through the name (../x, ..\x, a/b, absolute names);
  • a missing parent, with nothing created;
  • a relative, empty or file parent;
  • a symlinked parent;
  • a read-only parent;
  • the Windows rules, checked on every host;
  • the mapping to error codes, and every i18n key present in en.json.
• Vitest:
  • directory-browser.test.tsx:
    • the button appears only when the host asks for it;
    • Enter and the check button create the folder and move into it, and a confirm commits it;
    • the parent shows the new folder when going back up;
    • Escape cancels without closing the dialog;
    • blank names;
    • the localized already-exists and invalid-name errors, and the fallback message;
    • busy reporting, and no second submit while busy;
    • navigating away closes a draft;
    • Arabic.
  • workspace-folder-dialog.test.tsx: creating a folder and opening it with Next, and no New folder button when picking link targets.
  • platform.test.ts: directory picks ask for canCreateDirectories.
  • The existing i18n key-parity and ICU checks.
• Manual, in WebKit against codeg-server:
  • created a folder and opened it as a workspace;
  • an existing name, a name with a slash, and .. each showed their error;
  • Escape kept the dialog open;
  • the endpoint returned 200, 400, 404, 409 and 401 (without a token) as expected;
  • the Arabic, right-to-left UI.

[xintaofei]

codeg work task 287 is done — #881 (4 files, +292/-31).