feat: let the viewer pick the audio track

The streaming path mapped 0:a:0 unconditionally, so a dubbed film played in
whichever language was muxed first and the others were unreachable. The node
now enumerates the tracks in stream_init and honours audio_track in
stream_req; switching is the seek path, since one ffmpeg carries one track.

MNP 3.2, additive: the player draws its selector from the node's own list and
never from a version number, so an older node is never asked for a track it
would ignore. MNP_MIN_SUPPORTED does not move.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

6 files changed, 425 insertions, 41 deletions

diff --git a/packages/meshbay-node/src/meshbay_node/indexer/enrich.py b/packages/meshbay-node/src/meshbay_node/indexer/enrich.py
index 19ab9ce..6eeb1ef 100644
--- a/packages/meshbay-node/src/meshbay_node/indexer/enrich.py
+++ b/packages/meshbay-node/src/meshbay_node/indexer/enrich.py
@@ -238,11 +238,12 @@ class Enricher:
                 duration = cached_meta["duration"]
             else:
                 try:
-                    _codec, duration, _has_audio, width, height, _raw = await asyncio.wait_for(
+                    probe = await asyncio.wait_for(
                         probe_video(str(file_path)), timeout=PROBE_TIMEOUT_SECS)
+                    duration = probe.duration
                     fields["duration"] = int(duration) if duration else None
-                    fields["width"] = width
-                    fields["height"] = height
+                    fields["width"] = probe.width
+                    fields["height"] = probe.height
                 except Exception as e:
                     log.warning("Probe failed for %s: %s", file_path, e)
                 await self._media_cache.put_video_meta(
diff --git a/packages/meshbay-node/src/meshbay_node/media_probe.py b/packages/meshbay-node/src/meshbay_node/media_probe.py
index ad668fa..7858ebe 100644
--- a/packages/meshbay-node/src/meshbay_node/media_probe.py
+++ b/packages/meshbay-node/src/meshbay_node/media_probe.py
@@ -8,6 +8,7 @@ already imports from) can call it too without a circular import.
 
 import asyncio
 import json
+from dataclasses import dataclass, field
 
 _H264_PROFILES = {"Baseline": "42", "Main": "4d", "High": "64", "High 10": "6e"}
 
@@ -21,12 +22,46 @@ _H264_PROFILES = {"Baseline": "42", "Main": "4d", "High": "64", "High 10": "6e"}
 BROWSER_INCOMPATIBLE_VIDEO_CODECS = frozenset({"hevc"})
 
 
-async def probe_video(
-    path: str,
-) -> tuple[str | None, float, bool, int | None, int | None, str | None]:
+@dataclass(frozen=True)
+class AudioTrack:
     """
-    Probe video file with ffprobe, return (MSE codec string, duration,
-    has_audio, width, height, raw video codec name).
+    One selectable audio track.
+
+    **`ordinal` is the position among the audio streams, not the container
+    stream index**, because that is what `-map 0:a:<n>` takes. A file whose
+    audio sits at container indices 1, 2 and 3 has ordinals 0, 1 and 2, and
+    mapping `0:a:1` on the container index would silently serve the third
+    track — the failure this field's name exists to prevent.
+    """
+    ordinal: int
+    language: str | None
+    title: str | None
+    codec_name: str | None
+    channels: int | None
+
+
+@dataclass
+class VideoProbe:
+    """
+    What one ffprobe call says about a video file.
+
+    A dataclass rather than the tuple this used to return: the tuple had six
+    positional fields, `has_audio` sat third and `raw_codec_name` sixth, and
+    adding a seventh for the track list would have made every call site a
+    counting exercise.
+    """
+    codec: str | None
+    duration: float
+    has_audio: bool
+    width: int | None
+    height: int | None
+    raw_codec_name: str | None
+    audio_tracks: list[AudioTrack] = field(default_factory=list)
+
+
+async def probe_video(path: str) -> VideoProbe:
+    """
+    Probe a video file with ffprobe.
 
     The audio half of the codec string is always "mp4a.40.2" (AAC-LC) or
     absent — never the source's real audio codec — because the streaming
@@ -51,6 +86,13 @@ async def probe_video(
     H264. It answered it by refusing until 2026-09-09, which read to the
     operator as a broken file rather than as an unwired code path.
 
+    **Every audio track is reported, not just the first.** The streaming path
+    transcodes audio unconditionally, so serving the second track costs exactly
+    what serving the first costs and the choice is the viewer's to make; a
+    library of dubbed films is one where the first track is a language half the
+    group does not want. `has_audio` stays as the single question the muxing
+    decisions ask, and is now `bool(audio_tracks)`.
+
     width/height come from the same ffprobe call (one extra `-show_entries`
     field, no second process spawn) — resolution is deliberately never
     guessed from the filename (docs/mediacenter.md §3.5).
@@ -58,7 +100,9 @@ async def probe_video(
     from meshbay_node.platform import ffprobe_cmd
     proc = await asyncio.create_subprocess_exec(
         ffprobe_cmd(), "-v", "error",
-        "-show_entries", "stream=codec_name,profile,level,codec_type,width,height",
+        "-show_entries",
+        "stream=codec_name,profile,level,codec_type,width,height,channels",
+        "-show_entries", "stream_tags=language,title",
         "-show_entries", "format=duration",
         "-of", "json", path,
         stdout=asyncio.subprocess.PIPE, stderr=asyncio.subprocess.PIPE,
@@ -69,9 +113,9 @@ async def probe_video(
 
     v_codec = ""
     raw_codec_name: str | None = None
-    has_audio = False
     width: int | None = None
     height: int | None = None
+    audio_tracks: list[AudioTrack] = []
     for s in info.get("streams", []):
         if s.get("codec_type") == "video" and not v_codec:
             cn = s.get("codec_name", "")
@@ -89,9 +133,26 @@ async def probe_video(
             width = s.get("width")
             height = s.get("height")
         elif s.get("codec_type") == "audio":
-            has_audio = True
+            tags = s.get("tags") or {}
+            audio_tracks.append(AudioTrack(
+                # Counted here, never read from `s["index"]` — see AudioTrack.
+                ordinal=len(audio_tracks),
+                language=(tags.get("language") or "").strip() or None,
+                title=(tags.get("title") or "").strip() or None,
+                codec_name=s.get("codec_name") or None,
+                channels=s.get("channels"),
+            ))
 
-    if not v_codec:
-        return None, duration, has_audio, width, height, raw_codec_name
-    codec = f"{v_codec},mp4a.40.2" if has_audio else v_codec
-    return codec, duration, has_audio, width, height, raw_codec_name
+    has_audio = bool(audio_tracks)
+    codec = None
+    if v_codec:
+        codec = f"{v_codec},mp4a.40.2" if has_audio else v_codec
+    return VideoProbe(
+        codec=codec,
+        duration=duration,
+        has_audio=has_audio,
+        width=width,
+        height=height,
+        raw_codec_name=raw_codec_name,
+        audio_tracks=audio_tracks,
+    )
diff --git a/packages/meshbay-node/src/meshbay_node/transport/webrtc_server.py b/packages/meshbay-node/src/meshbay_node/transport/webrtc_server.py
index 99ba3c9..b39941d 100644
--- a/packages/meshbay-node/src/meshbay_node/transport/webrtc_server.py
+++ b/packages/meshbay-node/src/meshbay_node/transport/webrtc_server.py
@@ -5948,11 +5948,14 @@ class WebRTCPeerSession:
         file_hash = bytes.fromhex(entry.id)
 
         try:
-            codec_str, duration, has_audio, _width, _height, raw_video_codec = \
-                await _probe_video(str(file_path))
+            probe = await _probe_video(str(file_path))
         except Exception as e:
             self._send({"type": "error", "detail": f"Probe failed: {e}"})
             return
+        codec_str = probe.codec
+        duration = probe.duration
+        has_audio = probe.has_audio
+        raw_video_codec = probe.raw_codec_name
 
         # No video stream at all is the only thing this path cannot serve, and
         # it is the only thing refused here. A source with no MSE codec string
@@ -6051,8 +6054,23 @@ class WebRTCPeerSession:
             codec_str = "avc1.640029,mp4a.40.2" if has_audio else "avc1.640029"
         else:
             codec_args = ["-c:v", "copy"]
+        # Which audio track. A dubbed film carries several and the first one is
+        # not a neutral default — it is whatever the person who muxed the file
+        # happened to put first, which across a real library is overwhelmingly
+        # one language. Out of range falls back to the first rather than
+        # refusing: the client's list comes from a `stream_init` that may
+        # predate the file being replaced on disk, and a viewer who asked for
+        # the second track of a file that now has one wants the film, not an
+        # error. `stream_init` says which track was actually used, the same way
+        # it says which `start` was actually used and for the same reason.
+        try:
+            audio_track = int(msg.get("audio_track", 0) or 0)
+        except (TypeError, ValueError):
+            audio_track = 0
+        if not 0 <= audio_track < len(probe.audio_tracks):
+            audio_track = 0
         if has_audio:
-            map_args += ["-map", "0:a:0"]
+            map_args += ["-map", f"0:a:{audio_track}"]
             # Downmixed to stereo: a WEB-DL's 5.1 track becomes 6-channel AAC
             # with no "-ac", which ffprobe and VLC accept fine but which some
             # browsers' MSE decoder rejects outright once real fragments are
@@ -6081,6 +6099,22 @@ class WebRTCPeerSession:
             # this is what the client adds back (`SourceBuffer.timestampOffset`)
             # to put the fragments where they belong on the timeline.
             "start": start,
+            # The track list is how a client discovers that this node can
+            # switch language at all — there is no version check anywhere in
+            # the player. A node that does not send it gets no selector, and
+            # the client then never sends `audio_track` to a peer that would
+            # ignore it and serve the wrong language without saying so.
+            "audio_tracks": [
+                {
+                    "i": tr.ordinal,
+                    "lang": tr.language,
+                    "title": tr.title,
+                    "codec": tr.codec_name,
+                    "ch": tr.channels,
+                }
+                for tr in probe.audio_tracks
+            ],
+            "audio_track": audio_track if has_audio else None,
         })
 
         # A client that says nothing gets the old behaviour, which is why this
@@ -6097,8 +6131,10 @@ class WebRTCPeerSession:
         self._stream_started_at = time.monotonic()
         self._stream_segments = 0
         reason = "eof"
-        log.info("stream: stream_init sent file=%s paced=%s credits=%d start=%.1fs",
-                 file_id[:12], paced, self._stream_credit, start)
+        log.info("stream: stream_init sent file=%s paced=%s credits=%d start=%.1fs "
+                 "audio=%s/%d",
+                 file_id[:12], paced, self._stream_credit, start,
+                 audio_track if has_audio else "-", len(probe.audio_tracks))
         try:
             while True:
                 if paced and not await self._await_stream_credit():
diff --git a/packages/meshbay-node/tests/test_stream_audio_track_selection.py b/packages/meshbay-node/tests/test_stream_audio_track_selection.py
new file mode 100644
index 0000000..53781f9
--- /dev/null
+++ b/packages/meshbay-node/tests/test_stream_audio_track_selection.py
@@ -0,0 +1,285 @@
+"""
+The viewer picks which audio track is streamed.
+
+A dubbed film carries several audio tracks and the streaming path used to map
+`0:a:0` unconditionally, so it played in whichever language happened to be
+muxed first. Across a real library that is overwhelmingly one language, and the
+others could not be reached at all.
+
+The tracks here are told apart by **amplitude**, not by their tags: each is the
+same tone at a different volume, so an assertion about which track was served
+is measured from the decoded audio of the reassembled stream and cannot be
+satisfied by mapping the wrong one. Tags would only prove that the node copied
+a string it was given.
+
+Like the other streaming tests, these spawn real ffmpeg/ffprobe against small
+synthetic files rather than asserting against the source text.
+"""
+
+import re
+import shutil
+import subprocess
+from pathlib import Path
+
+import pytest
+from cryptography.hazmat.primitives.asymmetric.ed25519 import Ed25519PrivateKey
+
+from meshbay_common.crypto import generate_gek
+from meshbay_common.webcrypto import chunk_key_aes, decrypt_chunk_aes
+from meshbay_node.indexer.group_index import GroupIndex
+from meshbay_node.transport.webrtc_server import WebRTCPeerSession, _probe_video
+
+from conftest import needs_subprocess, one_root
+
+_HAVE_FFMPEG = shutil.which("ffmpeg") and shutil.which("ffprobe")
+pytestmark = [
+    pytest.mark.asyncio,
+    pytest.mark.skipif(not _HAVE_FFMPEG, reason="ffmpeg/ffprobe not installed"),
+    needs_subprocess,
+]
+
+# Each track's tone is attenuated by a different amount, far enough apart that
+# an AAC round trip cannot blur one into another. Index in this list is the
+# audio ordinal the node is asked for.
+_TRACK_GAIN = [1.0, 0.1, 0.01]          # 0 dB, -20 dB, -40 dB
+_TRACK_LANG = ["fre", "eng", "spa"]
+_TRACK_TITLE = ["Surround", "Original", None]
+
+
+def _make_multitrack_clip(path: Path) -> None:
+    """~1s of H264 video plus three audio tracks at descending volumes.
+
+    The video is muxed first, so the audio streams sit at container indices 1,
+    2 and 3 while their audio *ordinals* are 0, 1 and 2 — the gap that
+    `-map 0:a:<n>` is indexed by and that a probe reading `s["index"]` would
+    get wrong.
+    """
+    args = ["ffmpeg", "-hide_banner", "-loglevel", "error", "-y",
+            "-f", "lavfi", "-i", "testsrc=size=320x240:rate=25:duration=1"]
+    for gain in _TRACK_GAIN:
+        args += ["-f", "lavfi",
+                 "-i", f"sine=frequency=440:duration=1:sample_rate=48000,"
+                       f"volume={gain}"]
+    args += ["-map", "0:v:0"]
+    for i in range(len(_TRACK_GAIN)):
+        args += ["-map", f"{i + 1}:a:0"]
+    args += ["-c:v", "libx264", "-preset", "ultrafast", "-c:a", "aac"]
+    for i, lang in enumerate(_TRACK_LANG):
+        args += [f"-metadata:s:a:{i}", f"language={lang}"]
+        if _TRACK_TITLE[i]:
+            args += [f"-metadata:s:a:{i}", f"title={_TRACK_TITLE[i]}"]
+    args.append(str(path))
+    subprocess.run(args, check=True, capture_output=True)
+
+
+def _session(tmp_path: Path, video_path: Path, gek: bytes):
+    import blake3
+    file_bytes = video_path.read_bytes()
+    file_id = blake3.blake3(file_bytes).hexdigest()
+
+    sk_node = Ed25519PrivateKey.generate()
+    index = GroupIndex(group_id="g" * 32, sk_node=sk_node, gek=gek)
+    from meshbay_common.protocol import IndexEntry
+    index.add_entry(IndexEntry(
+        id=file_id, name=video_path.name, path=video_path.parent.name,
+        size=len(file_bytes), type="video", added_at=0))
+
+    session = WebRTCPeerSession.__new__(WebRTCPeerSession)
+    session._ctx = {
+        "roots": one_root(video_path.parent),
+        "index": index,
+        "gek": gek,
+        "sk_node": sk_node,
+        "max_concurrent_streams": 4,
+    }
+    session._group_id = None
+    session._user_id = "tester"
+    session._stream_stopped = False
+    session._stream_keepalives = 0
+    session.sent = []
+    session._send = session.sent.append
+    session._audit = lambda *a, **k: None
+    return session, file_id
+
+
+def _reassemble(sent: list[dict], gek: bytes, file_id: str) -> bytes:
+    file_hash = bytes.fromhex(file_id)
+    segments = sorted(
+        (m for m in sent if m.get("type") == "stream_data"),
+        key=lambda m: m["segment_index"])
+    out = b""
+    for m in segments:
+        key = chunk_key_aes(gek, file_hash, m["segment_index"])
+        out += decrypt_chunk_aes(key, m["nonce"], m["ct"])
+    return out
+
+
+def _mean_volume_db(path: Path) -> float:
+    """What ffmpeg's volumedetect measures in the decoded audio."""
+    proc = subprocess.run(
+        ["ffmpeg", "-hide_banner", "-i", str(path), "-af", "volumedetect",
+         "-f", "null", "-"],
+        capture_output=True, text=True)
+    m = re.search(r"mean_volume:\s*(-?\d+(?:\.\d+)?) dB", proc.stderr)
+    assert m, f"volumedetect said nothing usable: {proc.stderr[-400:]}"
+    return float(m.group(1))
+
+
+async def _stream(tmp_path: Path, clip: Path, msg_extra: dict):
+    gek = generate_gek()
+    session, file_id = _session(tmp_path, clip, gek)
+    await session._stream_video_inner(
+        {"file_id": file_id, "start": 0, "credits": 0, **msg_extra})
+    errors = [m for m in session.sent if m.get("type") == "error"]
+    assert not errors, f"streaming must not fail: {errors}"
+    init = next(m for m in session.sent if m.get("type") == "stream_init")
+    return session, file_id, gek, init
+
+
+async def _streamed_volume(tmp_path: Path, clip: Path, msg_extra: dict, tag: str):
+    session, file_id, gek, init = await _stream(tmp_path, clip, msg_extra)
+    out = tmp_path / f"out-{tag}.mp4"
+    out.write_bytes(_reassemble(session.sent, gek, file_id))
+    return _mean_volume_db(out), init
+
+
+async def test_probe_enumerates_every_track_by_ordinal_not_container_index(tmp_path):
+    """The trap this feature is one wrong line away from.
+
+    `-map 0:a:1` counts audio streams; `s["index"]` counts every stream in the
+    container. With a video stream muxed first the two never agree, and a probe
+    reporting container indices would make the client ask for track 1 and be
+    served track 2 — silently, since both are real audio.
+    """
+    clip = tmp_path / "clip.mkv"
+    _make_multitrack_clip(clip)
+
+    probe = await _probe_video(str(clip))
+
+    assert [tr.ordinal for tr in probe.audio_tracks] == [0, 1, 2]
+    assert [tr.language for tr in probe.audio_tracks] == _TRACK_LANG
+    assert probe.has_audio is True
+    # The container really does disagree, or the assertion above proves nothing.
+    raw = subprocess.run(
+        ["ffprobe", "-v", "error", "-select_streams", "a",
+         "-show_entries", "stream=index", "-of", "csv=p=0", str(clip)],
+        check=True, capture_output=True, text=True)
+    assert [int(x) for x in raw.stdout.split()] == [1, 2, 3], (
+        "the fixture must put audio at container indices that differ from the "
+        "ordinals, or it cannot tell the two apart")
+
+
+async def test_probe_reports_the_title_tag_when_the_muxer_wrote_one(tmp_path):
+    """Two tracks in one language are one menu entry repeated without it."""
+    clip = tmp_path / "clip.mkv"
+    _make_multitrack_clip(clip)
+
+    probe = await _probe_video(str(clip))
+
+    assert [tr.title for tr in probe.audio_tracks] == _TRACK_TITLE
+    assert all(tr.channels == 1 for tr in probe.audio_tracks)
+
+
+async def test_the_requested_audio_track_is_the_one_streamed(tmp_path):
+    """Measured from the decoded audio, not from a tag the node echoed back."""
+    clip = tmp_path / "clip.mkv"
+    _make_multitrack_clip(clip)
+
+    first, init_first = await _streamed_volume(tmp_path, clip, {"audio_track": 0}, "0")
+    third, init_third = await _streamed_volume(tmp_path, clip, {"audio_track": 2}, "2")
+
+    assert init_first["audio_track"] == 0
+    assert init_third["audio_track"] == 2
+    # -40 dB of attenuation between them; anything under 15 dB of measured
+    # separation means the same track was served twice.
+    assert first - third > 15, (
+        f"track 0 ({first} dB) and track 2 ({third} dB) decoded to the same "
+        "loudness, so the requested track was not the one mapped")
+
+
+async def test_no_audio_track_asked_for_still_means_the_first(tmp_path):
+    """A client that says nothing gets exactly what it got before."""
+    clip = tmp_path / "clip.mkv"
+    _make_multitrack_clip(clip)
+
+    silent, init_silent = await _streamed_volume(tmp_path, clip, {}, "default")
+    explicit, _ = await _streamed_volume(tmp_path, clip, {"audio_track": 0}, "explicit")
+
+    assert init_silent["audio_track"] == 0
+    assert abs(silent - explicit) < 2
+
+
+async def test_an_out_of_range_track_falls_back_to_the_first_and_says_so(tmp_path):
+    """The client's list can predate the file being replaced on disk.
+
+    A viewer who asked for the second track of a file that now has one wants
+    the film, not an error — and `stream_init` has to report the track actually
+    used, the same way it reports the `start` actually used.
+    """
+    clip = tmp_path / "clip.mkv"
+    _make_multitrack_clip(clip)
+
+    got, init = await _streamed_volume(tmp_path, clip, {"audio_track": 9}, "oob")
+    expected, _ = await _streamed_volume(tmp_path, clip, {"audio_track": 0}, "base")
+
+    assert init["audio_track"] == 0, "stream_init must not echo the impossible request"
+    assert abs(got - expected) < 2
+
+
+async def test_a_malformed_track_number_is_not_an_error(tmp_path):
+    clip = tmp_path / "clip.mkv"
+    _make_multitrack_clip(clip)
+
+    for bad in ("two", None, -1, 1.5):
+        _, _, _, init = await _stream(tmp_path, clip, {"audio_track": bad})
+        assert init["audio_track"] in (0, 1), f"{bad!r} produced {init['audio_track']!r}"
+
+
+async def test_stream_init_lists_the_tracks_for_the_client_to_choose_from(tmp_path):
+    """The list is the whole capability negotiation.
+
+    The player draws its selector from this and from nothing else — there is no
+    version check in it — so a node that sends no list gets no selector and is
+    never sent an `audio_track` it would ignore and answer in the wrong
+    language.
+    """
+    clip = tmp_path / "clip.mkv"
+    _make_multitrack_clip(clip)
+
+    _, _, _, init = await _stream(tmp_path, clip, {})
+
+    assert [tr["i"] for tr in init["audio_tracks"]] == [0, 1, 2]
+    assert [tr["lang"] for tr in init["audio_tracks"]] == _TRACK_LANG
+    assert init["audio_tracks"][0]["title"] == "Surround"
+    assert init["audio_tracks"][2]["title"] is None
+
+
+async def test_a_single_track_file_reports_a_list_of_one(tmp_path):
+    """Not an empty list: the player decides on length, and a one-entry list is
+    how it knows there is nothing to choose rather than nothing to report."""
+    clip = tmp_path / "mono.mkv"
+    subprocess.run(
+        ["ffmpeg", "-hide_banner", "-loglevel", "error", "-y",
+         "-f", "lavfi", "-i", "testsrc=size=320x240:rate=25:duration=1",
+         "-f", "lavfi", "-i", "sine=frequency=440:duration=1:sample_rate=48000",
+         "-c:v", "libx264", "-preset", "ultrafast", "-c:a", "aac", str(clip)],
+        check=True, capture_output=True)
+
+    _, _, _, init = await _stream(tmp_path, clip, {})
+
+    assert len(init["audio_tracks"]) == 1
+    assert init["audio_track"] == 0
+
+
+async def test_a_file_with_no_audio_reports_no_track_at_all(tmp_path):
+    clip = tmp_path / "silent.mkv"
+    subprocess.run(
+        ["ffmpeg", "-hide_banner", "-loglevel", "error", "-y",
+         "-f", "lavfi", "-i", "testsrc=size=320x240:rate=25:duration=1",
+         "-c:v", "libx264", "-preset", "ultrafast", "-an", str(clip)],
+        check=True, capture_output=True)
+
+    _, _, _, init = await _stream(tmp_path, clip, {"audio_track": 1})
+
+    assert init["audio_tracks"] == []
+    assert init["audio_track"] is None
diff --git a/packages/meshbay-node/tests/test_stream_audio_transcode.py b/packages/meshbay-node/tests/test_stream_audio_transcode.py
index 959cc91..92518ba 100644
--- a/packages/meshbay-node/tests/test_stream_audio_transcode.py
+++ b/packages/meshbay-node/tests/test_stream_audio_transcode.py
@@ -150,15 +150,15 @@ async def test_probe_video_reports_aac_regardless_of_source_audio_codec(tmp_path
     clip = tmp_path / "clip.mkv"
     _make_clip(clip, acodec="eac3", channels=6)
 
-    codec, duration, has_audio, width, height, raw_codec = await _probe_video(str(clip))
+    probe = await _probe_video(str(clip))
 
-    assert has_audio is True
-    assert duration > 0
-    assert codec is not None
-    assert "eac3" not in codec and "ec-3" not in codec
-    assert "mp4a.40.2" in codec
-    assert (width, height) == (320, 240)
-    assert raw_codec == "h264"
+    assert probe.has_audio is True
+    assert probe.duration > 0
+    assert probe.codec is not None
+    assert "eac3" not in probe.codec and "ec-3" not in probe.codec
+    assert "mp4a.40.2" in probe.codec
+    assert (probe.width, probe.height) == (320, 240)
+    assert probe.raw_codec_name == "h264"
 
 
 async def test_probe_video_handles_no_audio_track(tmp_path):
@@ -170,10 +170,11 @@ async def test_probe_video_handles_no_audio_track(tmp_path):
         check=True, capture_output=True,
     )
 
-    codec, duration, has_audio, width, height, raw_codec = await _probe_video(str(clip))
+    probe = await _probe_video(str(clip))
 
-    assert has_audio is False
-    assert codec is not None and "," not in codec, \
+    assert probe.has_audio is False
+    assert probe.audio_tracks == []
+    assert probe.codec is not None and "," not in probe.codec, \
         "no audio track must not produce a dangling ',' or a fake audio codec"
-    assert (width, height) == (320, 240)
-    assert raw_codec == "h264"
+    assert (probe.width, probe.height) == (320, 240)
+    assert probe.raw_codec_name == "h264"
diff --git a/packages/meshbay-node/tests/test_stream_video_transcode.py b/packages/meshbay-node/tests/test_stream_video_transcode.py
index 69f4c2d..b165af4 100644
--- a/packages/meshbay-node/tests/test_stream_video_transcode.py
+++ b/packages/meshbay-node/tests/test_stream_video_transcode.py
@@ -191,10 +191,10 @@ async def test_probe_video_reports_raw_codec_name_for_hevc(tmp_path):
     clip = tmp_path / "clip.mkv"
     _make_hevc_clip(clip)
 
-    codec, duration, has_audio, width, height, raw_codec = await _probe_video(str(clip))
+    probe = await _probe_video(str(clip))
 
-    assert raw_codec == "hevc"
-    assert codec is not None and codec.startswith("hev1.")
+    assert probe.raw_codec_name == "hevc"
+    assert probe.codec is not None and probe.codec.startswith("hev1.")
 
 
 @needs_mp3
@@ -206,13 +206,13 @@ async def test_probe_video_reports_no_codec_string_for_mpeg4(tmp_path):
     clip = tmp_path / "clip.avi"
     _make_mpeg4_clip(clip)
 
-    codec, duration, has_audio, width, height, raw_codec = await _probe_video(str(clip))
+    probe = await _probe_video(str(clip))
 
-    assert raw_codec == "mpeg4"
-    assert codec is None, (
+    assert probe.raw_codec_name == "mpeg4"
+    assert probe.codec is None, (
         "a codec string for MPEG-4 Part 2 would be one no browser can act on")
-    assert has_audio is True
-    assert (width, height) == (320, 240)
+    assert probe.has_audio is True
+    assert (probe.width, probe.height) == (320, 240)
 
 
 @needs_mp3