feat(settings): a real theme selector, and Graphite as a third theme

crates/moon-core/src/config/mod.rs

@@ -286,7 +286,7 @@ pub struct AppConfig {
     pub log_retention_days: u32,
     /// Addition to base UI font sizes in logical pixels. Defaults to +3.
     pub ui_font_delta: f32,
-    /// Dark/light MoonUI theme (plaintext settings.toml).
+    /// Interface theme mode (plaintext settings.toml); Graphite shares the dark colour set.
     pub ui_theme_mode: UiThemeMode,
     /// Overall UI geometry scale. Defaults to 1.0.
     pub ui_scale: f32,
@@ -307,11 +307,11 @@ pub struct AppConfig {
     pub(in crate::config) next_uid: UidCounter,
     /// Terminal hotkeys (plaintext hotkeys.toml).
     pub hotkeys: HotkeysConfig,
-    /// Chart theme per UI mode (dark/light) in separate portable theme.toml.
+    /// Chart theme per colour set (dark/light) in separate portable theme.toml.
     pub theme: ChartThemeSet,
-    /// Order-line styles per theme (dark/light) in separate portable orders.toml.
+    /// Order-line styles per colour set (dark/light) in separate portable orders.toml.
     pub orders: OrdersStyleSet,
-    /// Detect-type badges (code + per-type colors, per theme) in separate portable badges.json.
+    /// Detect-type badges (code plus per-type colours for each colour set) in badges.json.
     pub badges: BadgesConfig,
     /// Runtime flag (NOT serialized): `settings.toml` EXISTS but could not be read because of
     /// permissions, a share, or an unhydrated cloud placeholder, so memory holds DEFAULTS rather
@@ -893,9 +893,9 @@ impl AppConfig {
         !self.servers.is_empty() || self.next_uid.get() > Self::FIRST_ISSUED_UID
     }
 
-    /// Chart theme for the active UI mode (dark/light according to `ui_theme_mode`).
+    /// Chart theme for the active UI mode's colour set; Graphite uses the dark entry.
     pub fn chart_theme(&self) -> &ChartTheme {
-        self.theme.get(self.ui_theme_mode == UiThemeMode::Light)
+        self.theme.get(self.ui_theme_mode.is_light())
     }
 
     /// A group is meaningful only while at least one core references it. Do not save orphans,

crates/moon-core/src/config/moonbot_import/apply.rs

@@ -59,11 +59,19 @@ pub fn apply_local(
 fn apply_item(cfg: &mut AppConfig, item: &SettingChange) -> bool {
     match (&item.value, item.id.as_str()) {
         (PlannedValue::UiThemeLight(light), "ui.theme_mode") => {
-            cfg.ui_theme_mode = if *light {
-                UiThemeMode::Light
-            } else {
-                UiThemeMode::Dark
-            };
+            // The plan carries a theme as ONE BOOLEAN, so "dark" cannot say WHICH dark theme it
+            // means. Writing `Dark` unconditionally would convert Graphite to Dark — and it would
+            // do it on a row the preview marks `same` (`plan.rs:145` compares the same boolean),
+            // so the user is told nothing changes and then loses their theme. Move the mode only
+            // when the colour SET actually differs; importing "dark" onto a mode that already
+            // draws the dark set is genuinely a no-op.
+            if *light != cfg.ui_theme_mode.is_light() {
+                cfg.ui_theme_mode = if *light {
+                    UiThemeMode::Light
+                } else {
+                    UiThemeMode::Dark
+                };
+            }
             true
         }
         (PlannedValue::SplitParts(parts), "hotkey.split_parts") => {

crates/moon-core/src/config/schema.rs

@@ -121,14 +121,39 @@ pub fn clamp_chart_stack_height(value: u16) -> u16 {
     value.clamp(120, 2000)
 }
 
+/// Interface theme the user picked on the General tab.
+///
+/// THREE modes, but only TWO colour sets. `Graphite` is a middle theme — mid-tone neutral
+/// surfaces between `Dark`'s near-black and `Light` — and it shares the DARK set for badges,
+/// order styles, lines and the chart theme. Nothing here is a third table.
+///
+/// [`Self::is_light`] is the only sanctioned way to ask which set a mode draws. A bare equality
+/// test against the `Light` variant reads correctly today and then silently answers "not light,
+/// therefore dark" for a fourth variant added later — which is exactly how Graphite would have
+/// been handed the light set at half of its call sites.
 #[derive(Clone, Copy, Debug, Default, PartialEq, Eq, Hash, Serialize, Deserialize)]
 #[serde(rename_all = "lowercase")]
 pub enum UiThemeMode {
     Light,
+    /// Mid-tone neutral surfaces with light text; draws the DARK colour set.
+    Graphite,
     #[default]
     Dark,
 }
 
+impl UiThemeMode {
+    /// Whether this mode draws the LIGHT colour set.
+    ///
+    /// `Graphite` is dark-leaning and answers `false`, so every per-mode colour table
+    /// (`badges`, `orders`, `lines`, the chart theme) keeps its two entries.
+    ///
+    /// Returns:
+    ///     `true` only for [`UiThemeMode::Light`].
+    pub const fn is_light(self) -> bool {
+        matches!(self, UiThemeMode::Light)
+    }
+}
+
 /// Interface theme a profile receives when `settings.toml` has never been written.
 ///
 /// Deliberately NOT the `Default` of [`UiThemeMode`]. `Default` is what serde substitutes for an
@@ -314,7 +339,7 @@ pub struct SettingsFile {
     /// into 13 px at 1x without zooming the whole interface.
     #[serde(default = "default_ui_font_delta")]
     pub ui_font_delta: f32,
-    /// Dark/light MoonUI theme. This plaintext setting is neither a secret nor the chart theme.
+    /// Interface theme mode. Graphite shares dark colour data; this plaintext setting is not secret.
     #[serde(default)]
     pub ui_theme_mode: UiThemeMode,
     /// Overall UI geometry scale. It currently has no public control but is stored beside

crates/moon-core/src/config/schema/tests.rs

@@ -82,3 +82,32 @@ fn a_core_issued_strategy_id_cannot_break_the_whole_settings_file() {
         );
     }
 }
+
+/// Catches dropping `config/schema.rs:UiThemeMode`'s `serde(rename_all = "lowercase")`.
+/// Without it, Graphite persists as `"Graphite"`, which the same build cannot read from settings.
+#[test]
+fn graphite_theme_mode_round_trips_as_the_lowercase_settings_value() {
+    let stored = SettingsFile {
+        ui_theme_mode: UiThemeMode::Graphite,
+        ..SettingsFile::default()
+    };
+    let persisted = toml::to_string(&stored).expect("settings file must serialize");
+    assert!(
+        persisted
+            .lines()
+            .any(|line| line == "ui_theme_mode = \"graphite\""),
+        "settings.toml must persist the lowercase Graphite spelling"
+    );
+    let reread: SettingsFile =
+        toml::from_str("ui_theme_mode = \"graphite\"").expect("stored graphite must load");
+    assert_eq!(reread.ui_theme_mode, UiThemeMode::Graphite);
+}
+
+/// Catches changing `config/schema.rs:UiThemeMode::is_light` to include Graphite.
+/// That would route Graphite through every light color branch in badges, orders, lines, and charts.
+#[test]
+fn graphite_is_dark_while_light_remains_the_only_light_mode() {
+    assert!(UiThemeMode::Light.is_light());
+    assert!(!UiThemeMode::Graphite.is_light());
+    assert!(!UiThemeMode::Dark.is_light());
+}

crates/moon-core/src/config/tests.rs

@@ -1,6 +1,6 @@
 //! Runtime configuration-constructor regressions.
 
-use super::{AppConfig, BadgesConfig, ChartThemeSet, OrdersStyleSet};
+use super::{AppConfig, BadgesConfig, ChartThemeSet, OrdersStyleSet, UiThemeMode};
 
 /// Regression target: removing `ensure_server_group_configs` from
 /// `AppConfig::build_plaintext_config` leaves the environment-backed core without durable
@@ -111,3 +111,12 @@ fn a_plaintext_config_keeps_the_settings_it_was_given() {
     // quiet minute takes the screenshot with it.
     assert_eq!(config.main_idle_close_secs, 0);
 }
+
+/// Catches `config/mod.rs:AppConfig::chart_theme` treating Graphite as light.
+/// If it selects the light chart set, Graphite's dark interface paints charts with the wrong palette.
+#[test]
+fn graphite_chart_theme_uses_the_existing_dark_chart_set() {
+    let mut config = AppConfig::blank(None);
+    config.ui_theme_mode = UiThemeMode::Graphite;
+    assert_eq!(config.chart_theme(), &config.theme.dark);
+}