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# Architecture

Storage has two runtime paths: filesystem access and upload persistence.

## Filesystem access flow

1. `fs()` calls `FileSystemFactory::get()`
2. config is imported if needed
3. requested adapter (or `fs.default`) is resolved
4. adapter is wrapped in `FileSystem`
5. wrapper is cached per adapter name in the process

Practical effect: repeated `fs('local')` calls reuse the same wrapper instance.

## Wrapper model

`FileSystem` is a delegating wrapper around one adapter.

Unsupported adapter methods are rejected with exceptions instead of being ignored.

## Upload flow

`UploadedFile` runs this sequence:

1. parse upload metadata
2. detect extension + MIME from the local temp file
3. load MIME policy (defaults + optional config)
4. validate the temp file and destination strategy
5. write locally or forward the temp file content to a remote adapter
6. optionally run post-save image modification against the saved path

Practical effect: upload inspection and staging still depend on the local adapter, even when the final destination is remote.

## Cloud composition

Cloud backends are composed from:

* adapter implementation
* cloud app/token service wiring from config

This keeps app-level usage consistent (`fs()` + wrapper API) while backend auth/token lifecycle stays in services/config.


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