feat(coding-agent): improve terminal theme detection

packages/coding-agent/test/theme-detection.test.ts

@@ -0,0 +1,49 @@
+import { describe, expect, it } from "vitest";
+import {
+	detectTerminalBackground,
+	getThemeForRgbColor,
+	parseOsc11BackgroundColor,
+} from "../src/modes/interactive/theme/theme.js";
+
+describe("detectTerminalBackground", () => {
+	it("uses the COLORFGBG background color index", () => {
+		expect(detectTerminalBackground({ env: { COLORFGBG: "0;15" } })).toMatchObject({
+			theme: "light",
+			source: "COLORFGBG",
+			confidence: "high",
+		});
+		expect(detectTerminalBackground({ env: { COLORFGBG: "15;0" } })).toMatchObject({
+			theme: "dark",
+			source: "COLORFGBG",
+			confidence: "high",
+		});
+	});
+
+	it("uses the last COLORFGBG field as the background", () => {
+		expect(detectTerminalBackground({ env: { COLORFGBG: "0;7;15" } }).theme).toBe("light");
+	});
+
+	it("defaults to dark without terminal background hints", () => {
+		expect(detectTerminalBackground({ env: {} })).toMatchObject({
+			theme: "dark",
+			source: "fallback",
+			confidence: "low",
+		});
+	});
+});
+
+describe("parseOsc11BackgroundColor", () => {
+	it("parses 16-bit OSC 11 rgb responses", () => {
+		expect(parseOsc11BackgroundColor("\x1b]11;rgb:0000/8000/ffff\x07")).toEqual({ r: 0, g: 128, b: 255 });
+	});
+
+	it("parses OSC 11 hex responses", () => {
+		expect(parseOsc11BackgroundColor("\x1b]11;#ffffff\x1b\\")).toEqual({ r: 255, g: 255, b: 255 });
+		expect(parseOsc11BackgroundColor("\x1b]11;#000000\x07")).toEqual({ r: 0, g: 0, b: 0 });
+	});
+
+	it("classifies RGB colors by luminance", () => {
+		expect(getThemeForRgbColor({ r: 8, g: 8, b: 8 })).toBe("dark");
+		expect(getThemeForRgbColor({ r: 250, g: 250, b: 250 })).toBe("light");
+	});
+});