fix(local-audio): reference-aware cleanup, upload quota, stricter validation

Uploaded local files were deleted whenever a track left the current slot,
with no check on whether the file was still needed — causing data loss in
several flows. Replace with reference-aware cleanup: a file is deleted only
once it has been played AND is no longer referenced by ANY bot's queue
(BotManager.getReferencedLocalSongIds wired into the provider via
setInUseResolver), with the sweep run AFTER each queue mutation.

Fixes:
- play-song replay no longer deletes the file it is about to play
- loop / repeat-all / prev no longer destroy uploads mid-cycle
- a shared upload queued on multiple bots is not deleted while still in use
- !play / play-playlist / play-album clean the whole replaced queue, and an
  empty/failed playlist/album load keeps the previous queue + files intact
- bound disk use with an upload quota (evict oldest UNREFERENCED files)
- validate uploads by extension against the audio whitelist (never trust the
  client Content-Type); the stored extension is always a known audio type

Deletion now unlinks the file FIRST and drops the record only on success,
with a bounded non-blocking retry for briefly-locked files (Windows/ffmpeg),
so a failed unlink never orphans a file or diverges index.json. The quota
never evicts the just-uploaded file, and long filenames keep their extension.

Adds src/music/local.test.ts covering the cleanup lifecycle, quota eviction,
and upload validation.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/music/local.test.ts

@@ -0,0 +1,221 @@
+import { describe, it, expect, beforeEach, afterEach } from "vitest";
+import { mkdtempSync, rmSync, existsSync, writeFileSync } from "node:fs";
+import { tmpdir } from "node:os";
+import { join } from "node:path";
+import { LocalMusicProvider } from "./local.js";
+
+let dir: string;
+
+beforeEach(() => {
+  dir = mkdtempSync(join(tmpdir(), "local-audio-test-"));
+});
+
+afterEach(() => {
+  rmSync(dir, { recursive: true, force: true });
+});
+
+// Seed real files + an index.json so we can exercise the cleanup lifecycle
+// without invoking the ffmpeg duration probe that uploadAudio runs.
+function makeRecord(id: string, bytes = 16) {
+  const filePath = join(dir, `${id}.mp3`);
+  writeFileSync(filePath, Buffer.alloc(bytes, 1));
+  return {
+    id,
+    name: id,
+    artist: "本地上传",
+    album: "本地音乐",
+    duration: 0,
+    coverUrl: "",
+    platform: "local" as const,
+    filePath,
+    originalName: `${id}.mp3`,
+    uploadedAt: "1970-01-01T00:00:00.000Z",
+    size: bytes,
+    mimeType: "audio/mpeg",
+  };
+}
+
+function seed(records: ReturnType<typeof makeRecord>[]) {
+  writeFileSync(join(dir, "index.json"), JSON.stringify(records), "utf8");
+}
+
+describe("LocalMusicProvider cleanup lifecycle", () => {
+  it("sweep keeps referenced and never-played files, deletes only played+unreferenced", async () => {
+    const a = makeRecord("a");
+    const b = makeRecord("b");
+    const c = makeRecord("c");
+    seed([a, b, c]);
+    const p = new LocalMusicProvider(dir);
+    const refs = new Set<string>(["a"]); // "a" still sits in a queue somewhere
+    p.setInUseResolver(() => refs);
+
+    await p.getSongUrl("a"); // played, but referenced
+    await p.getSongUrl("b"); // played and unreferenced
+    // "c" was never played (e.g. uploaded but not queued)
+
+    const deleted = p.sweepUnreferenced();
+
+    expect(deleted).toEqual(["b"]);
+    expect(existsSync(a.filePath)).toBe(true); // referenced → kept
+    expect(existsSync(b.filePath)).toBe(false); // played + unreferenced → deleted
+    expect(existsSync(c.filePath)).toBe(true); // never played → kept
+  });
+
+  it("a played song still in the queue survives the sweep and stays replayable (loop / prev)", async () => {
+    const a = makeRecord("a");
+    seed([a]);
+    const p = new LocalMusicProvider(dir);
+    const refs = new Set<string>(["a"]); // loop queue still references it
+    p.setInUseResolver(() => refs);
+
+    await p.getSongUrl("a"); // first pass plays it
+    p.sweepUnreferenced(); // "playback_finished" sweep
+
+    expect(existsSync(a.filePath)).toBe(true);
+    expect((await p.getSongUrl("a"))?.url).toBe(a.filePath); // next loop pass works
+  });
+
+  it("re-playing a queued local song does not delete it (play-song order)", async () => {
+    const a = makeRecord("a");
+    seed([a]);
+    const p = new LocalMusicProvider(dir);
+    // Mirror the fixed endpoint order: the song is (re)added to the queue
+    // BEFORE the sweep runs, so it is referenced when we sweep.
+    const refs = new Set<string>(["a"]);
+    p.setInUseResolver(() => refs);
+
+    await p.getSongUrl("a"); // played once
+    p.sweepUnreferenced(); // sweep fired after the replay re-queued it
+    expect(existsSync(a.filePath)).toBe(true);
+    expect(await p.getSongUrl("a")).not.toBeNull();
+  });
+
+  it("deletes a played file once it leaves every queue", async () => {
+    const a = makeRecord("a");
+    seed([a]);
+    const p = new LocalMusicProvider(dir);
+    let refs = new Set<string>(["a"]);
+    p.setInUseResolver(() => refs);
+
+    await p.getSongUrl("a");
+    p.sweepUnreferenced();
+    expect(existsSync(a.filePath)).toBe(true); // still queued
+
+    refs = new Set<string>(); // queue cleared
+    p.sweepUnreferenced();
+    expect(existsSync(a.filePath)).toBe(false); // now removed
+    expect(await p.getSongUrl("a")).toBeNull();
+  });
+
+  it("never deletes anything when the reference resolver throws", async () => {
+    const a = makeRecord("a");
+    seed([a]);
+    const p = new LocalMusicProvider(dir);
+    p.setInUseResolver(() => {
+      throw new Error("manager unavailable");
+    });
+    await p.getSongUrl("a");
+    expect(p.sweepUnreferenced()).toEqual([]);
+    expect(existsSync(a.filePath)).toBe(true);
+  });
+});
+
+describe("LocalMusicProvider upload validation", () => {
+  it("rejects a spoofed Content-Type with a non-audio extension", async () => {
+    const p = new LocalMusicProvider(dir);
+    await expect(
+      p.uploadAudio({
+        buffer: Buffer.from("malicious"),
+        originalName: "evil.exe",
+        mimeType: "application/octet-stream",
+      }),
+    ).rejects.toThrow();
+  });
+
+  it("rejects an unknown extension even when the mime claims audio", async () => {
+    const p = new LocalMusicProvider(dir);
+    await expect(
+      p.uploadAudio({
+        buffer: Buffer.from("x"),
+        originalName: "evil.html",
+        mimeType: "audio/mpeg",
+      }),
+    ).rejects.toThrow();
+  });
+
+  it("rejects an empty file", async () => {
+    const p = new LocalMusicProvider(dir);
+    await expect(
+      p.uploadAudio({ buffer: Buffer.alloc(0), originalName: "a.mp3" }),
+    ).rejects.toThrow();
+  });
+});
+
+describe("LocalMusicProvider quota", () => {
+  it("evicts oldest unreferenced uploads beyond maxFiles", async () => {
+    const a = makeRecord("a");
+    const b = makeRecord("b");
+    seed([b, a]); // newest-first: b newer than a
+    const p = new LocalMusicProvider(dir, { maxFiles: 2 });
+    p.setInUseResolver(() => new Set<string>());
+
+    // Upload a third valid file → over the 2-file cap → evict the oldest ("a").
+    await p.uploadAudio({
+      buffer: Buffer.alloc(16, 7),
+      originalName: "c.mp3",
+      mimeType: "audio/mpeg",
+    });
+
+    expect(existsSync(a.filePath)).toBe(false); // oldest evicted
+    expect(existsSync(b.filePath)).toBe(true);
+    const result = await p.search("");
+    expect(result.songs.map((s) => s.id).sort()).not.toContain("a");
+  });
+
+  it("does not evict a referenced upload even when over the cap", async () => {
+    const a = makeRecord("a");
+    const b = makeRecord("b");
+    seed([b, a]);
+    const p = new LocalMusicProvider(dir, { maxFiles: 1 });
+    p.setInUseResolver(() => new Set<string>(["a"])); // "a" is queued
+
+    await p.uploadAudio({
+      buffer: Buffer.alloc(16, 7),
+      originalName: "c.mp3",
+      mimeType: "audio/mpeg",
+    });
+
+    expect(existsSync(a.filePath)).toBe(true); // protected: still queued
+  });
+
+  it("never evicts the just-uploaded file, even when every older file is referenced", async () => {
+    const a = makeRecord("a");
+    seed([a]);
+    const p = new LocalMusicProvider(dir, { maxFiles: 1 });
+    p.setInUseResolver(() => new Set<string>(["a"])); // the only older file is queued
+
+    const song = await p.uploadAudio({
+      buffer: Buffer.alloc(16, 7),
+      originalName: "c.mp3",
+      mimeType: "audio/mpeg",
+    });
+
+    // The returned song must actually exist and be playable — not a phantom.
+    expect(await p.getSongUrl(song.id)).not.toBeNull();
+  });
+});
+
+describe("LocalMusicProvider filename handling", () => {
+  it("accepts a long filename without dropping its extension", async () => {
+    const p = new LocalMusicProvider(dir);
+    const longName = "x".repeat(300) + ".mp3";
+    // Must not throw the "unsupported format" error — the extension survives.
+    const song = await p.uploadAudio({
+      buffer: Buffer.alloc(16, 1),
+      originalName: longName,
+      mimeType: "audio/mpeg",
+    });
+    expect(song.id).toBeTruthy();
+    expect(await p.getSongUrl(song.id)).not.toBeNull();
+  });
+});