## Title

`sprimo-tauri` settings window invoke errors for sprite-pack switch and always-on-top toggle.

## Severity

P1

## Environment

- OS: Windows
- App version/build: `sprimo-tauri` workspace runtime
- Renderer/backend details: Tauri UI settings pop-out window
- Evidence screenshots:
  - `issues/screenshots/issue3.png`
  - `issues/screenshots/issue3-b.png`

## Summary

When using the settings pop-out window, changing character or toggling always-on-top shows
invoke argument validation errors and the action fails to apply.

## Reproduction Steps

1. Start `sprimo-tauri` and open tray menu `Settings`.
2. Change `Character` selection.
3. Toggle `Always on top`.
4. Observe red error banner in settings window.

## Expected Result

- Character change applies successfully and updates active sprite pack.
- Always-on-top toggle applies successfully and updates main window z-order state.
- No invoke argument error appears.

## Actual Result

- Character change fails with:
  - `invalid args 'packIdOrPath' for command 'set_sprite_pack'`
- Always-on-top toggle fails with:
  - `invalid args 'alwaysOnTop' for command 'set_always_on_top'`

## Root Cause Analysis

- Frontend invoke payload keys were sent in snake_case (`pack_id_or_path`, `always_on_top`).
- Tauri JS invoke argument mapping for these Rust command parameter names expects camelCase
  keys (`packIdOrPath`, `alwaysOnTop`).
- Because the required keys were missing from Tauri's perspective, command handlers were not run.

## Fix Plan

1. Update settings invoke payload keys to Tauri-compatible camelCase names.
2. Add typed helper wrappers for settings invokes to centralize argument naming.
3. Rebuild UI and run Rust compile checks.
4. Perform runtime manual validation and capture after screenshot evidence.

## Implementation Notes

Implemented in `frontend/tauri-ui/src/main.tsx`:

1. Added typed invoke wrappers:
- `invokeSetSpritePack(packIdOrPath)`
- `invokeSetScale(scale)`
- `invokeSetVisibility(visible)`
- `invokeSetAlwaysOnTop(alwaysOnTop)`

2. Updated failing settings call sites to use wrappers and camelCase payload keys.

## Verification

### Commands Run

- [x] `npm --prefix frontend/tauri-ui run build`
- [x] `cargo check -p sprimo-tauri`

### Visual Checklist

- [x] Before screenshot(s): `issues/screenshots/issue3.png`
- [x] Before screenshot(s): `issues/screenshots/issue3-b.png`
- [ ] After screenshot(s): `issues/screenshots/issue3-after-YYYYMMDD-HHMMSS.png`

### Result

- Status: `Fix Implemented`
- Notes: compile/build checks pass; runtime visual verification still required.

## Status History

- `2026-02-14 00:00` - reporter - `Reported` - settings errors captured in `issue3.png` and `issue3-b.png`.
- `2026-02-14 00:00` - codex - `Triaged` - localized to invoke argument key mismatch.
- `2026-02-14 00:00` - codex - `Fix Implemented` - updated settings invoke keys to camelCase via typed wrappers.

## Closure

- Current Status: `Fix Implemented`
- Close Date:
- Owner:
- Linked PR/commit: