port bezel theme system into the theme crate

crates/theme/src/registry.rs

@@ -5,7 +5,7 @@ use std::sync::Arc;
 use anyhow::{Context as AnyhowContext, Error};
 use gpui::{App, AppContext, AssetSource, Context, Entity, Global, SharedString};
 
-use crate::ThemeFamily;
+use crate::{ThemeFamily, ThemeMode};
 
 pub fn init(cx: &mut App) {
     ThemeRegistry::set_global(cx.new(ThemeRegistry::new), cx);
@@ -57,8 +57,11 @@ impl ThemeRegistry {
         // Load the theme file from the assets
         let content = asset.load(path)?.context("Theme not found")?;
 
-        // Parse the JSON content into a Theme Family struct
-        let theme: ThemeFamily = serde_json::from_slice(&content)?;
+        // Parse the JSON content into a Theme Family struct, and re-derive the
+        // tokens from the legacy fields the file carries.
+        let mut theme: ThemeFamily = serde_json::from_slice(&content)?;
+        theme.light.rederive_tokens(ThemeMode::Light);
+        theme.dark.rederive_tokens(ThemeMode::Dark);
 
         Ok(theme)
     }