[markusbrand]

Summary

Fixes a reproducible IPC argument deserialization bug in the desktop client (client-tauri) where creating a user from the Settings UI consistently fails with:
command api_create_user missing required key firstName

Root Cause

In client-tauri/src/Settings.tsx, handleCreateUser invokes Tauri command api_create_user using snake_case arguments:

await invoke("api_create_user", {
  email: newUserEmail,
  first_name: newUserFirst,
  last_name: newUserLast,
});

However, Tauri v2's #[tauri::command] procedural macro converts Rust parameter names (email, first_name, last_name) to lowerCamelCase (email, firstName, lastName) for IPC argument deserialization. Because Settings.tsx supplied first_name and last_name, Tauri rejected the call at runtime before invoking the backend.

Changes

• Updated client-tauri/src/Settings.tsx to include firstName: newUserFirst and lastName: newUserLast, while also retaining first_name and last_name for defense-in-depth compatibility.
• Added OpenSpec change artifacts in openspec/changes/fix-client-create-user-ipc-arguments/ tracking proposal, delta specs, design, and verified tasks.

Verification

• (cd client-tauri && npm run build): TypeScript compilation and Vite packaging passed cleanly.
• (cd client-tauri/src-tauri && cargo test): All 21 unit tests passed.