file_security.rs resolves asset paths against CWD, not asset_root

[staging-devin-ai-integration]

Problem

When asset_root is set to a directory other than the process CWD, a path-space mismatch occurs:

• Asset handlers (audio/images/fonts/plugins) now store and serve files from <asset_root>/samples/...
• The API returns logical paths like samples/audio/user/clip.opus
• Downstream file-reader validation in file_security.rs (lines 29–44) resolves those logical paths against the process working directory, not asset_root

This means that if asset_root != CWD, selecting a returned asset path in a pipeline would either fail validation or read a stale file from <cwd>/samples/....

Current Impact

None in production. The asset_root field is hidden from the config schema (#[schemars(skip)]) and defaults to current_dir() when unset. It was introduced in #520 purely for test isolation (replacing figment::Jail CWD mutation with TempDir).

Fix needed if asset_root is ever promoted to user-facing config

file_security.rs path resolution and any other downstream consumers of samples/... paths would need to resolve against asset_root instead of (or in addition to) CWD.

Related

• PR refactor(assets): replace CWD-relative paths with configurable asset_root #520 — introduced asset_root
• Issue Refactor asset handlers to accept configurable asset root (eliminate hardcoded relative paths) #478 — the CWD race that motivated the refactor