SetCVar and RegisterCVar read their arguments as 1.12.1 does: a number as %.14g text, "0" for a value with no string form, the reference usage text, realmList/realmName/scriptMemory read-only in the world, and CVAR_UPDATE fired inside the call for every token (#557)

`SetCVar` and `RegisterCVar` now read their arguments as the reference's bindings do (`0x488c10`, `0x488b00`):

- a number is stored as Lua's `%.14g` text (`luaV_tostring` `0x6f7c80`), so the stock Sound slider's 0.4 stores `"0.40000000596046"`;
- a value with no string form (nil, absent, boolean, table) stores `"0"` (`0x488c98`, `0x488b6f`), so unticking a stock Sound options box no longer raises and music can be switched off there;
- the reference's usage texts (`0x84235c`, `0x8422e8`);
- `realmList`, `realmName` and `scriptMemory` are read-only to Lua `SetCVar` in the world (`0x48f566`-`0x48f584`), and host writes still land;
- `CVAR_UPDATE` fires inside the call for every string token, changed or not (`0x488cad`-`0x488cd5`, `SignalEvent2` `0x703f50`).

Verified: 7 new VM tests, a stock Sound window test off the chain and a world-entry read-only test, each failing with the change undone; `scripts/gates.sh` green. Built on macOS; no platform seam touched.

Fixes #167
Fixes #139
Fixes #547

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

crates/benilla-app/src/ui_script/lifecycle.rs

@@ -306,6 +306,13 @@ pub(crate) fn load_ingame_ui_on_world_entry(world: &mut World) {
         .and_then(|r| r.realm.as_ref().map(|r| r.name.clone()))
         .unwrap_or_default();
     script.set_realm_name(&realm);
+    // `CGGameUI::InitializeGame` flags these read-only before `UI_Init` loads anything
+    // (`0x48f566`-`0x48f584`), so an in-game `SetCVar` of one raises, logout handlers included;
+    // `ShutdownGame` clears them (`0x491240`), and here the flags die with this VM. The host's
+    // own realm writes are engine writes, which the flag does not stop.
+    for name in benilla_ui::script::IN_WORLD_READ_ONLY_CVARS {
+        script.set_cvar_read_only(name, true);
+    }
     // The player too, before the addon walk. The record first: the reference's
     // `UnitName`/`UnitRace`/`UnitClass`/`UnitSex` read only a copy of the char-enum row made at the
     // Enter World commit (`0x5abd9e`) and never cleared, and each rebuilt VM is told once. The

crates/benilla-app/src/ui_script/options_tests.rs

@@ -3567,8 +3567,7 @@ fn the_status_bar_text_row_pins_the_numerals_the_moment_it_is_clicked() {
         s.take_cvar_changes(),
         vec![("statusBarText".to_string(), "1".to_string())]
     );
-    // No repaint and no XP tick: only the queued `CVAR_UPDATE`.
-    s.tick(0.0);
+    // No repaint, no XP tick and no frame: only the `CVAR_UPDATE` the click fired.
     assert!(
         s.eval::<bool>("return MainMenuBarExpText:IsShown()")
             .unwrap(),
@@ -3577,7 +3576,6 @@ fn the_status_bar_text_row_pins_the_numerals_the_moment_it_is_clicked() {
 
     s.run("BenillaOptionsFrameContainerBodyInterfaceRowStatusTextCheck:Click()")
         .unwrap();
-    s.tick(0.0);
     assert!(!s
         .eval::<bool>("return MainMenuBarExpText:IsShown()")
         .unwrap());

crates/benilla-app/src/ui_script/shipped_xml_tests.rs

@@ -1453,6 +1453,54 @@ fn the_stock_sound_options_window_loads_hidden_and_the_alias_is_gone() {
     );
 }
 
+/// The stock Sound window's boxes write `this:GetChecked()` as is (`SoundOptionsFrame.lua:82`),
+/// which is nil once unticked, and `SetCVar` stores that as "0" (`0x488c98`); its sliders write
+/// `GetValue()`, a single-precision number stored as Lua's `%.14g` text (`0x6f7c80`).
+#[test]
+fn the_stock_sound_window_turns_a_box_off_and_stores_a_slider_as_lua_text() {
+    let _data = benilla_formats::wow_data_or_skip!();
+    let mut s = benilla_ui::script::UiScript::new().unwrap();
+    s.set_screen_size(1024.0, 768.0);
+    s.set_unit(
+        "player",
+        Some(benilla_ui::script::UnitState {
+            exists: true,
+            name: Some("Probefour".into()),
+            level: 60,
+            ..Default::default()
+        }),
+    );
+    let failures = super::load_default_ui(&s);
+    assert!(failures.is_empty(), "manifest load errors: {failures:#?}");
+    s.set_cvar_host("EnableMusic", "1");
+    s.run("this = SoundOptionsFrameOkay SoundOptionsFrame_Load()")
+        .unwrap();
+    let _ = s.take_cvar_changes();
+    let checked = "return SoundOptionsFrameCheckButton5:GetChecked() and true or false";
+    assert!(s.eval::<bool>(checked).unwrap(), "Enable Music starts on");
+
+    s.run("SoundOptionsFrameCheckButton5:Click()").unwrap();
+    assert!(s.errors().is_empty(), "script errors: {:?}", s.errors());
+    assert!(!s.eval::<bool>(checked).unwrap());
+    assert_eq!(
+        s.take_cvar_changes(),
+        vec![("EnableMusic".to_string(), "0".to_string())],
+        "the unticked box turns music off"
+    );
+    s.run("SoundOptionsFrameCheckButton5:Click()").unwrap();
+    assert_eq!(
+        s.take_cvar_changes(),
+        vec![("EnableMusic".to_string(), "1".to_string())]
+    );
+
+    s.run("SoundOptionsFrameSlider3:SetValue(0.4)").unwrap();
+    assert_eq!(
+        s.eval::<String>("return GetCVar(\"MusicVolume\")").unwrap(),
+        "0.40000000596046"
+    );
+    assert!(s.errors().is_empty(), "script errors: {:?}", s.errors());
+}
+
 /// The stock Video Options window loads hidden (`OptionsFrame.xml:5`) and owns the `OptionsFrame`
 /// name; ours is `BenillaOptionsFrame`, which the ESC menu opens and the stock "options window
 /// open?" consumers see only through the `GameMenuFrame.xml` wrappers.

crates/benilla-app/src/ui_script/world_entry_tests.rs

@@ -270,6 +270,50 @@ fn the_login_arms_the_world_latch_and_the_logout_spends_it() {
     let _ = std::fs::remove_dir_all(&tmp);
 }
 
+/// `CGGameUI::InitializeGame` flags `realmList`, `realmName` and `scriptMemory` read-only for the
+/// world session (`0x48f566`-`0x48f584`) and `ShutdownGame` clears them (`0x491240`): an
+/// in-game `SetCVar` of one raises, through a reload too, and the character screen's does not.
+#[test]
+fn the_realm_cvars_are_read_only_to_lua_only_in_the_world() {
+    let _l = ENV_LOCK
+        .lock()
+        .unwrap_or_else(std::sync::PoisonError::into_inner);
+    let (tmp, _c, _h) = hermetic_probe("readonly");
+    let mut world = booted_world();
+    world.init_resource::<super::LeavingWorldArmed>();
+    let set = |world: &World, chunk: &str| {
+        let s = world.non_send_resource::<benilla_ui::script::UiScript>();
+        // A bare test world has no registry to seed the VM from.
+        s.register_cvars(crate::cvars::registered_pairs());
+        s.run(chunk).map_err(|e| e.to_string())
+    };
+
+    assert_eq!(
+        set(&world, "SetCVar(\"realmList\", \"glue.example.org\")"),
+        Ok(()),
+        "the character screen's VM may write it"
+    );
+
+    log_in_as(&mut world, "Onehunter", 1);
+    for name in ["realmList", "realmName"] {
+        let err = set(&world, &format!("SetCVar({name:?}, \"x\")")).expect_err(name);
+        assert!(err.contains(&format!("\"{name}\" is read-only")), "{err}");
+    }
+    assert_eq!(set(&world, "SetCVar(\"MusicVolume\", 0.5)"), Ok(()));
+
+    reload(&mut world, crate::char_select::ClientState::InWorld);
+    assert!(
+        set(&world, "SetCVar(\"realmList\", \"x\")").is_err(),
+        "a reload keeps the flag, as the reference's rows keep theirs"
+    );
+
+    super::end_ui_session(&mut world);
+    assert_eq!(set(&world, "SetCVar(\"realmList\", \"x\")"), Ok(()));
+
+    drop(world);
+    let _ = std::fs::remove_dir_all(&tmp);
+}
+
 /// The reference's one guard in the shutdown tail: `0x490bd0` tests the active player's GUID pair
 /// (`0x490bee call 0x468550`, `0x490bf3 or eax,edx`) and with none jumps (`0x490bf5 je 0x490c25`)
 /// past only the `PLAYER_LEAVING_WORLD` fire, `0x490c20 call 0x490a80`; in-world roots fire both.