Module writable_folder 

Cross-platform access to a user-chosen writable folder.

This is the write-side complement of crate::file_picker: where the choosers read content the user selects, this lets an app persist its own data into a folder the user grants — a local directory on desktop, a Storage Access Framework tree on Android — and read it back on later runs. The motivating use is cross-device sync, where each device writes a small document into a shared folder (e.g. on a Tailnet/WebDAV mount) and reads its peers’.

Two halves:

• crate::launcher::rememberWritableFolderLauncher presents the system chooser and hands back the opaque, durable handle string the app stores. The launcher owns the request across host recreation.
• open_writable_folder is synchronous and thread-safe. It rebuilds a WritableFolderStore from a stored handle, so a background worker can read and write without touching the UI thread.

Stores expose whole-file operations, FolderEntry display metadata, and chunked FolderReader/FolderWriter streams for payloads that should not be buffered. Read-only or unreachable folders surface as FolderError::ReadOnly / FolderError::Io so callers can degrade gracefully. Backends: desktop (std::fs), Android (SAF tree URIs), iOS (security-scoped bookmarks). The web has no writable-folder concept and returns FolderError::Unsupported.

Structs

FolderEntry

Display metadata for one file in a writable folder.

Enums

FolderError

Errors produced by writable-folder I/O.

Traits

FolderReader

Chunked reader over one file in a writable folder.

FolderWriter

Chunked writer over one file in a writable folder.

WritableFolderStore

Synchronous, thread-safe access to a user-chosen writable folder.

Functions

open_writable_folder

Reopens a writable folder from a stored handle. Synchronous and callable from any thread; returns None only when writable folders are unsupported here.

set_writable_folder_store_factory

Registers the platform store factory (Android, iOS). Called once at startup. No-op if already set.

Type Aliases

WritableFolderStoreRef

Shared handle to a WritableFolderStore.