feature: Phase 18.3 — Opus delivery transport (?format= stream + seek sidecar endpoint)

DeepDrftPublic.Client/Clients/TrackMediaClient.cs

@@ -2,6 +2,7 @@ using System.Net;
 using System.Net.Http.Headers;
 using System.Net.Http.Json;
 using DeepDrftModels.DTOs;
+using DeepDrftModels.Enums;
 using Microsoft.Extensions.DependencyInjection;
 using NetBlocks.Models;
 
@@ -45,23 +46,37 @@ public class TrackMediaClient
     }
 
     /// <summary>
-    /// Fetches the WAV stream for a track via an HTTP Range request starting at a
+    /// Fetches the audio stream for a track via an HTTP Range request starting at a
     /// file-absolute byte offset. <paramref name="byteOffset"/> is the position from
-    /// the start of the file on disk (including the WAV header) — callers seeking into
-    /// audio data must add the header size themselves. The cancellation token aborts
-    /// the in-flight server connection rather than leaving the server draining bytes
-    /// into a dead socket.
+    /// the start of the file on disk (including any container/header bytes) — callers
+    /// seeking into audio data must add the header size themselves. The cancellation
+    /// token aborts the in-flight server connection rather than leaving the server
+    /// draining bytes into a dead socket.
+    /// <para>
+    /// <paramref name="format"/> selects the delivery rendering (Phase 18): the default
+    /// <see cref="AudioFormat.Lossless"/> sends no <c>format</c> query param, so existing
+    /// callers hit the byte-identical pre-Phase-18 endpoint; <see cref="AudioFormat.Opus"/>
+    /// requests the low-data Ogg Opus artifact, which the server resolves and falls back to
+    /// lossless when absent (C2). The response <see cref="TrackMediaResponse.ContentType"/>
+    /// reports the format actually served, so the JS decoder dispatches on the real bytes.
+    /// </para>
     /// </summary>
     public async Task<ApiResult<TrackMediaResponse>> GetTrackMedia(
         string trackId,
         long byteOffset = 0,
+        AudioFormat format = AudioFormat.Lossless,
         CancellationToken cancellationToken = default)
     {
         try
         {
             // Same URL for every seek — only the Range header differs. byteOffset 0 is
             // not special-cased: "bytes=0-" requests the whole file from the start.
-            using var request = new HttpRequestMessage(HttpMethod.Get, $"api/track/{trackId}");
+            // Lossless omits the format param entirely so the request is byte-identical to
+            // the pre-Phase-18 endpoint; only Opus appends ?format=opus.
+            var uri = format == AudioFormat.Lossless
+                ? $"api/track/{trackId}"
+                : $"api/track/{trackId}?format={format.ToString().ToLowerInvariant()}";
+            using var request = new HttpRequestMessage(HttpMethod.Get, uri);
             request.Headers.Range = new RangeHeaderValue(byteOffset, null);
 
             // Use HttpCompletionOption.ResponseHeadersRead to get stream immediately
@@ -115,4 +130,33 @@ public class TrackMediaClient
             return ApiResult<WaveformProfileDto>.CreateFailResult(e.Message);
         }
     }
+
+    /// <summary>
+    /// Fetches a track's Opus seek/setup sidecar — the combined OpusHead/OpusTags setup header plus the
+    /// granule→byte seek index (Phase 18). The caller (18.5 player wiring) fetches this once on track load
+    /// and parses it into the JS-side OpusSeekData before issuing any Opus seek. A 404 means no Opus
+    /// artifact / sidecar exists for the track (legacy row, not backfilled, or transcode failed); callers
+    /// treat that as "this track has no Opus seek data — stay on lossless" rather than an error, so it
+    /// surfaces as a fail result with a stable message rather than throwing (mirrors GetWaveformProfileAsync).
+    /// </summary>
+    public async Task<ApiResult<byte[]>> GetOpusSidecarAsync(string trackId, CancellationToken cancellationToken = default)
+    {
+        try
+        {
+            var response = await _http.GetAsync($"api/track/{trackId}/opus/seekdata", cancellationToken);
+            if (response.StatusCode == HttpStatusCode.NotFound)
+            {
+                return ApiResult<byte[]>.CreateFailResult("No Opus sidecar available");
+            }
+
+            response.EnsureSuccessStatusCode();
+
+            var bytes = await response.Content.ReadAsByteArrayAsync(cancellationToken);
+            return ApiResult<byte[]>.CreatePassResult(bytes);
+        }
+        catch (Exception e)
+        {
+            return ApiResult<byte[]>.CreateFailResult(e.Message);
+        }
+    }
 }