Keep fallback active while adding queued media

web/backend/src/MediaPlayer.ts

@@ -76,6 +76,7 @@ export class MediaPlayer {
     private activeEntryId: number | null = null;
     private activeUrl: string | null = null;
     private fallbackSuppressedUntilStart = false;
+    private fallbackPendingUrl: string | null = null;
     private browserUrl: string | null = null;
     private browserFallback = new ChromiumFallback((url) => {
         if (this.browserUrl === url) {
@@ -384,7 +385,10 @@ export class MediaPlayer {
     }
 
     public async append(url: string) {
-        await this.loadFile(url, "append-play");
+        const mode = this.browserUrl || this.fallbackPendingUrl || this.browserFallback.isRunning
+            ? "append"
+            : "append-play";
+        await this.loadFile(url, mode);
     }
 
     public async replace(url: string) {
@@ -740,6 +744,7 @@ export class MediaPlayer {
                             const hadBrowser = !!this.browserUrl || this.browserFallback.isRunning;
                             this.activeAttemptGeneration++;
                             this.fallbackSuppressedUntilStart = false;
+                            this.fallbackPendingUrl = null;
                             this.browserUrl = null;
                             if (hadBrowser) void this.browserFallback.stop();
                             const entryId = typeof response.playlist_entry_id === "number"
@@ -805,6 +810,7 @@ export class MediaPlayer {
         if (this.fallbackCandidates.has(file) &&
             (entryId === this.activeEntryId || (this.activeEntryId === null && !this.fallbackSuppressedUntilStart)) &&
             attemptGeneration === this.activeAttemptGeneration) {
+            this.fallbackPendingUrl = file;
             void this.startBrowserFallback(file, attemptGeneration, entryId);
         }
     }
@@ -851,6 +857,10 @@ export class MediaPlayer {
             }
         } catch (error) {
             console.error(`Failed to start Chromium fallback for ${url}:`, error);
+        } finally {
+            if (generation === this.activeAttemptGeneration && this.fallbackPendingUrl === url) {
+                this.fallbackPendingUrl = null;
+            }
         }
     }
 
@@ -860,6 +870,7 @@ export class MediaPlayer {
         this.activeEntryId = null;
         this.activeUrl = null;
         this.currentFile = null;
+        this.fallbackPendingUrl = null;
         this.browserUrl = null;
         await this.browserFallback.stop();
     }

web/backend/test/MediaPlayerFallback.test.cjs

@@ -5,6 +5,7 @@ const { MediaPlayer } = require("../build/MediaPlayer");
 const makePlayer = (url = "https://example.test/watch?v=abc", playlist = [{ id: 42, filename: url }]) => {
   const player = Object.create(MediaPlayer.prototype);
   const starts = [];
+  const commands = [];
   let stops = 0;
   const state = {
     eventSubscribers: [],
@@ -38,13 +39,14 @@ const makePlayer = (url = "https://example.test/watch?v=abc", playlist = [{ id:
       player.browserFallback.isRunning = false;
     },
   };
-  player.writeCommand = async (command) => {
+  player.writeCommand = async (command, args) => {
+    commands.push([command, args]);
     if (command === "loadfile") return { error: "success" };
     if (command === "get_property") return { data: playlist };
     return { error: "success" };
   };
   player.fetchMetadataAndNotify = async () => undefined;
-  return { player, starts, get stops() { return stops; }, set playlist(value) { playlist = value; } };
+  return { player, starts, commands, get stops() { return stops; }, set playlist(value) { playlist = value; } };
 };
 
 const begin = (player, entryId = 42) => player.receiveData(`${JSON.stringify({ event: "start-file", playlist_entry_id: entryId })}\n`);
@@ -84,12 +86,13 @@ test("actual MPV error opens the exact original URL and mirrors indeterminate st
 test("queue append leaves active A eligible when queued B is added", async () => {
   const a = "https://example.test/a";
   const b = "https://example.test/b";
-  const { player, starts } = makePlayer(a, [{ id: 42, filename: a }]);
+  const { player, starts, commands } = makePlayer(a, [{ id: 42, filename: a }]);
   player.fallbackCandidates.add(a);
   player.entryCandidates.set(42, a);
   begin(player, 42);
   await player.append(b);
   await settle();
+  assert.equal(commands.filter(([name]) => name === "loadfile").at(-1)[1][1], "append-play");
   send(player, { reason: "error", file_error: "failed A" }, 42);
   await settle();
   assert.deepEqual(starts, [a]);
@@ -97,6 +100,22 @@ test("queue append leaves active A eligible when queued B is added", async () =>
   assert.equal(player.fallbackCandidates.has(b), true);
 });
 
+test("queue append during fallback startup keeps browser A open without starting B", async () => {
+  const a = "https://example.test/a";
+  const b = "https://example.test/b";
+  const { player, starts, commands } = makePlayer(a, [{ id: 42, filename: a }]);
+  player.fallbackCandidates.add(a);
+  player.entryCandidates.set(42, a);
+  begin(player, 42);
+  send(player, { reason: "error", file_error: "failed A" }, 42);
+  await player.append(b);
+  await settle();
+  const load = commands.filter(([name]) => name === "loadfile").at(-1);
+  assert.equal(load[1][1], "append");
+  assert.deepEqual(starts, [a]);
+  assert.equal(player.browserUrl, a);
+});
+
 test("append then skipTo keeps the selected entry eligible for its actual MPV error", async () => {
   const url = "https://example.test/shared-original?x=1&y=2";
   const { player, starts } = makePlayer(url, [{ id: 42, filename: url }]);