Function resolve_client_session_args 

pub fn resolve_client_session_args(
    cfg: &mut SessionConfig,
    client_cwd: &Path,
) -> Result<(), String>

Resolve path-like arguments in cfg against client_cwd.

• system: path-like → read file contents; path-like but missing → Err.
• prompt_manifest: canonicalize; missing → Err.

Called from both thin clients (tui/attach.rs, cmd/attach.rs) before sending Hello. The in-process path (resolve_system_prompt in agent-core) is unchanged.