Fix theme updating when VS Code auto theme detection is on (#864)

Fix math formula color detection with autoDetectColorScheme setting

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: elliot <elliot.evans@posit.co>

Author: 3 people

.gitignore

@@ -17,3 +17,4 @@ public/dist
 /.luarc.json
 .vscode-test
 *.vsix
+*.timestamp-*.mjs

apps/lsp/src/config.ts

@@ -36,13 +36,15 @@ export interface Settings {
   readonly workbench: {
     readonly colorTheme: string;
   };
+  // from the host, not from a user setting. undefined if not yet received computed value.
+  computedThemeKind?: 'dark' | 'light';
   readonly quarto: {
     readonly logLevel: LogLevel;
     readonly path: string;
     readonly mathjax: {
       readonly scale: number;
       readonly extensions: MathjaxSupportedExtension[];
-    }
+    };
     readonly symbols: {
       readonly exportToWorkspace: 'default' | 'all' | 'none';
     };
@@ -83,8 +85,9 @@ export interface Settings {
 function defaultSettings(): Settings {
   return {
     workbench: {
-      colorTheme: 'Dark+'
+      colorTheme: 'Dark+',
     },
+    computedThemeKind: undefined,
     quarto: {
       logLevel: LogLevel.Warn,
       path: "",
@@ -125,7 +128,7 @@ function defaultSettings(): Settings {
         }
       }
     }
-  }
+  };
 }
 
 
@@ -182,6 +185,7 @@ export class ConfigurationManager extends Disposable {
         }
       }
     };
+
     this._onDidChangeConfiguration.fire(this._settings);
   }
 
@@ -207,6 +211,13 @@ export class ConfigurationManager extends Disposable {
   public getSettings(): Settings {
     return this._settings;
   }
+
+  public setComputedThemeKind(kind: "light" | "dark") {
+    if (this._settings.computedThemeKind !== kind) {
+      this._settings.computedThemeKind = kind;
+      this._onDidChangeConfiguration.fire(this._settings);
+    }
+  }
 }
 
 export function lsConfiguration(configManager: ConfigurationManager): LsConfiguration {
@@ -232,7 +243,12 @@ export function lsConfiguration(configManager: ConfigurationManager): LsConfigur
     },
     get colorTheme(): "light" | "dark" {
       const settings = configManager.getSettings();
-      return settings.workbench.colorTheme.includes("Light") ? "light" : "dark";
+      if (settings.computedThemeKind !== undefined) {
+        return settings.computedThemeKind;
+      }
+      else {
+        return settings.workbench.colorTheme.includes("Light") ? "light" : "dark";
+      }
     },
     get mathjaxScale(): number {
       return configManager.getSettings().quarto.mathjax.scale;
@@ -243,7 +259,7 @@ export function lsConfiguration(configManager: ConfigurationManager): LsConfigur
     get exportSymbolsToWorkspace(): 'default' | 'all' | 'none' {
       return configManager.getSettings().quarto.symbols.exportToWorkspace;
     }
-  }
+  };
 }
 
 export function getDiagnosticsOptions(configManager: ConfigurationManager): DiagnosticOptions {

apps/lsp/src/index.ts

@@ -214,6 +214,10 @@ connection.onInitialize((params: InitializeParams) => {
   };
 });
 
+// listen for color theme changes from the client
+connection.onNotification("quarto/didChangeActiveColorTheme", (params: { kind: 'light' | 'dark'; }) => {
+  configManager.setComputedThemeKind(params.kind);
+});
 // further config dependent initialization
 connection.onInitialized(async () => {
   logger.logNotification('initialized');
@@ -224,6 +228,7 @@ connection.onInitialized(async () => {
     logger.setConfigurationManager(configManager);
   }
 
+
   // initialize connection to quarto
   const workspaceFolders = await connection.workspace.getWorkspaceFolders();
   const workspaceDir = workspaceFolders?.length

apps/vscode/CHANGELOG.md

@@ -8,6 +8,7 @@
 
 - Fixed a bug where code blocks inside complex div structures (e.g., many `::: {.notes}` divs without preceding blank lines) were not detected as executable cells (<https://github.com/quarto-dev/quarto/pull/875>).
 - Added a public API that other extensions can query to get the Quarto CLI path, version, and availability (<https://github.com/quarto-dev/quarto/pull/879>).
+- Fixed a bug where the `autoDetectColorScheme` setting could cause equation previews to have a dark text on dark background and vice versa (<https://github.com/quarto-dev/quarto/pull/864/changes>)
 
 
 ## 1.127.0 (Release on 2025-12-17)

apps/vscode/src/lsp/client.ts

@@ -24,7 +24,9 @@ import {
   Definition,
   LogOutputChannel,
   Uri,
-  Diagnostic
+  Diagnostic,
+  window,
+  ColorThemeKind
 } from "vscode";
 import {
   LanguageClient,
@@ -153,12 +155,29 @@ export async function activateLsp(
     clientOptions
   );
 
+  // Helper to send current theme to LSP server
+  const sendThemeNotification = () => {
+    if (client) {
+      const kind = (window.activeColorTheme.kind === ColorThemeKind.Light || window.activeColorTheme.kind === ColorThemeKind.HighContrastLight) ? "light" : "dark";
+      client.sendNotification("quarto/didChangeActiveColorTheme", { kind });
+    }
+  };
+
+  // Listen for theme changes and notify the server
+  context.subscriptions.push(
+    window.onDidChangeActiveColorTheme(() => {
+      sendThemeNotification();
+    })
+  );
+
   // return once the server is running
   return new Promise<LanguageClient>((resolve, reject) => {
 
     const handler = client.onDidChangeState(e => {
       if (e.newState === State.Running) {
         handler.dispose();
+        // Send computed theme on startup
+        sendThemeNotification();
         resolve(client);
       } else if (e.newState === State.Stopped) {
         reject(new Error("Failed to start Quarto LSP Server"));