feat: detect first-run terminal theme (#5385)

packages/tui/src/tui.ts

@@ -8,6 +8,7 @@ import * as path from "node:path";
 import { performance } from "node:perf_hooks";
 import { isKeyRelease, matchesKey } from "./keys.ts";
 import type { Terminal } from "./terminal.ts";
+import { isOsc11BackgroundColorResponse, parseOsc11BackgroundColor, type RgbColor } from "./terminal-colors.ts";
 import { deleteKittyImage, getCapabilities, isImageLine, setCellDimensions } from "./terminal-image.ts";
 import { extractSegments, normalizeTerminalOutput, sliceByColumn, sliceWithWidth, visibleWidth } from "./utils.ts";
 
@@ -82,6 +83,11 @@ export interface Component {
 
 type InputListenerResult = { consume?: boolean; data?: string } | undefined;
 type InputListener = (data: string) => InputListenerResult;
+type PendingOsc11BackgroundQuery = {
+	settled: boolean;
+	resolve: ((rgb: RgbColor | undefined) => void) | undefined;
+	timer: NodeJS.Timeout | undefined;
+};
 
 /**
  * Interface for components that can receive focus and display a hardware cursor.
@@ -303,6 +309,8 @@ export class TUI extends Container {
 	private previousViewportTop = 0; // Track previous viewport top for resize-aware cursor moves
 	private fullRedrawCount = 0;
 	private stopped = false;
+	private pendingOsc11BackgroundReplies = 0;
+	private pendingOsc11BackgroundQueries: PendingOsc11BackgroundQuery[] = [];
 
 	// Overlay stack for modal components rendered on top of base content
 	private focusOrderCounter = 0;
@@ -720,6 +728,10 @@ export class TUI extends Container {
 	}
 
 	private handleInput(data: string): void {
+		if (this.consumeOsc11BackgroundResponse(data)) {
+			return;
+		}
+
 		if (this.inputListeners.size > 0) {
 			let current = data;
 			for (const listener of this.inputListeners) {
@@ -788,6 +800,30 @@ export class TUI extends Container {
 		}
 	}
 
+	private consumeOsc11BackgroundResponse(data: string): boolean {
+		if (this.pendingOsc11BackgroundReplies <= 0) {
+			return false;
+		}
+
+		if (!isOsc11BackgroundColorResponse(data)) {
+			return false;
+		}
+
+		const rgb = parseOsc11BackgroundColor(data);
+		this.pendingOsc11BackgroundReplies -= 1;
+		const query = this.pendingOsc11BackgroundQueries.shift();
+		if (query && !query.settled) {
+			query.settled = true;
+			if (query.timer) {
+				clearTimeout(query.timer);
+				query.timer = undefined;
+			}
+			query.resolve?.(rgb);
+			query.resolve = undefined;
+		}
+		return true;
+	}
+
 	private consumeCellSizeResponse(data: string): boolean {
 		// Response format: ESC [ 6 ; height ; width t
 		const match = data.match(/^\x1b\[6;(\d+);(\d+)t$/);
@@ -1561,4 +1597,32 @@ export class TUI extends Container {
 			this.terminal.hideCursor();
 		}
 	}
+
+	/**
+	 * Query the terminal's default background color with OSC 11 (`ESC ] 11 ; ? BEL`).
+	 * @param timeoutMs Query timeout in milliseconds.
+	 * @returns Promise containing the parsed RGB color, or undefined if it times out or fails to parse.
+	 */
+	queryTerminalBackgroundColor({ timeoutMs }: { timeoutMs: number }): Promise<RgbColor | undefined> {
+		return new Promise((resolve) => {
+			const query: PendingOsc11BackgroundQuery = {
+				settled: false,
+				resolve,
+				timer: undefined,
+			};
+
+			query.timer = setTimeout(() => {
+				if (query.settled) {
+					return;
+				}
+				query.settled = true;
+				query.timer = undefined;
+				query.resolve?.(undefined);
+				query.resolve = undefined;
+			}, timeoutMs);
+			this.pendingOsc11BackgroundQueries.push(query);
+			this.pendingOsc11BackgroundReplies += 1;
+			this.terminal.write("\x1b]11;?\x07");
+		});
+	}
 }