fork(fix): Clone AMLL 并修复 BUG

- 将AMLL Clone到本以地进行修复和优化(emm虽然这很不优雅但是暂时无时间做子模块和Fork)
- 修复在当前播放歌词行不可见的视口Seek会出现滚动偏移的问题

amll-local/packages/lyric/test/lys.test.ts

@@ -0,0 +1,136 @@
+import { describe, expect, it } from "vitest";
+import { parseLys, stringifyLys } from "../src/formats/lys";
+
+describe("lys", () => {
+	it("parses basic word-timestamped line", () => {
+		const lines = parseLys("[0]Hello(1000,500) World(1500,500)");
+
+		expect(lines).toHaveLength(1);
+		expect(lines[0].startTime).toBe(1000);
+		expect(lines[0].endTime).toBe(2000);
+		expect(lines[0].isBG).toBe(false);
+		expect(lines[0].isDuet).toBe(false);
+		expect(lines[0].words.map((w) => w.word)).toEqual(["Hello", " World"]);
+	});
+
+	it("parses bg + duet flags from prop and strips bg wrappers", () => {
+		const lines = parseLys("[8](Hello(1000,500)World(1500,500))");
+
+		expect(lines).toHaveLength(1);
+		expect(lines[0].isBG).toBe(true);
+		expect(lines[0].isDuet).toBe(true);
+		expect(lines[0].words.map((w) => w.word).join("")).toBe("HelloWorld");
+	});
+
+	it("handles CRLF and ignores lines without valid prop prefix", () => {
+		const lines = parseLys(
+			"no prop\r\n#comment\r\n{meta:true}\r\n[4]Hello(1000,500)World(1500,500)",
+		);
+
+		expect(lines).toHaveLength(1);
+		expect(lines[0].startTime).toBe(1000);
+		expect(lines[0].endTime).toBe(2000);
+	});
+
+	it("ignores lines with bad word timestamps", () => {
+		const lines = parseLys(
+			"[0]Hello(1000,500)\n[0]Bad(a,b)\n[0]AlsoBad(1000,-10)\n[0]World(2000,500)",
+		);
+
+		expect(lines).toHaveLength(2);
+		expect(lines[0].words.map((w) => w.word).join("")).toBe("Hello");
+		expect(lines[1].words.map((w) => w.word).join("")).toBe("World");
+	});
+
+	it("ignores empty lines and lines with only whitespace", () => {
+		const lines = parseLys(
+			"[0]   \n[3]\n[0]Hello(1000,500) World(1500,500)\n   \n\n[0]Next(2000,500) line(2500,500)\n   \n",
+		);
+		expect(lines).toHaveLength(2);
+		expect(lines[0].words[0].word).toBe("Hello");
+		expect(lines[1].words[0].word).toBe("Next");
+	});
+
+	it("stringifies words and preserves spaces", () => {
+		const result = stringifyLys([
+			{
+				startTime: 1000,
+				endTime: 2000,
+				words: [
+					{ startTime: 1000, endTime: 1500, word: "Hello", romanWord: "" },
+					{ startTime: 0, endTime: 0, word: " ", romanWord: "" },
+					{ startTime: 1500, endTime: 2000, word: "World", romanWord: "" },
+				],
+				translatedLyric: "",
+				romanLyric: "",
+				isBG: false,
+				isDuet: false,
+			},
+		]);
+
+		expect(result).toBe("[4]Hello (1000,500)World(1500,500)");
+	});
+
+	it("stringifies props according to duet/background presence", () => {
+		const result = stringifyLys([
+			{
+				startTime: 0,
+				endTime: 0,
+				words: [{ startTime: 1000, endTime: 1500, word: "A", romanWord: "" }],
+				translatedLyric: "",
+				romanLyric: "",
+				isBG: true,
+				isDuet: true,
+			},
+			{
+				startTime: 0,
+				endTime: 0,
+				words: [{ startTime: 2000, endTime: 2500, word: "B", romanWord: "" }],
+				translatedLyric: "",
+				romanLyric: "",
+				isBG: false,
+				isDuet: false,
+			},
+		]);
+
+		expect(result).toBe("[8]A(1000,500)\n[4]B(2000,500)");
+	});
+
+	it("normalizes invalid timestamps when stringifying", () => {
+		const result = stringifyLys([
+			{
+				startTime: 0,
+				endTime: 0,
+				words: [
+					{
+						startTime: Number.NaN,
+						endTime: Number.POSITIVE_INFINITY,
+						word: "Hello",
+						romanWord: "",
+					},
+					{
+						startTime: -1,
+						endTime: -2,
+						word: "World",
+						romanWord: "",
+					},
+				],
+				translatedLyric: "",
+				romanLyric: "",
+				isBG: false,
+				isDuet: false,
+			},
+		]);
+
+		expect(result).toBe("[4]Hello(0,0)World(0,0)");
+	});
+
+	it("keeps parse -> stringify -> parse stable for content and timing", () => {
+		const input = "[4]Hello(1000,500) World(1500,500)\n[8](Again(3000,500))";
+		const first = parseLys(input);
+		const text = stringifyLys(first);
+		const second = parseLys(text);
+
+		expect(second).toEqual(first);
+	});
+});