feat: Phase 10c — MSE video streaming (real-time playback)

Replace download-then-play VideoPlayer with MSE (MediaSource Extensions)
streaming. Node remuxes to fMP4 via ffmpeg, probes codecs with ffprobe,
and sends encrypted segments over DataChannel. Browser decrypts and
appends to SourceBuffer — playback starts within seconds.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

1 files changed, 62 insertions, 0 deletions

diff --git a/packages/meshbay-node/tests/test_webrtc_transport.py b/packages/meshbay-node/tests/test_webrtc_transport.py
index d3847ff..b6664e8 100644
--- a/packages/meshbay-node/tests/test_webrtc_transport.py
+++ b/packages/meshbay-node/tests/test_webrtc_transport.py
@@ -725,3 +725,65 @@ async def test_webrtc_stream_segment_missing_file(sk_node, sk_hub, gek, shared_d
 
     await browser_pc.close()
     await transport.close_all()
+
+
+@pytest.mark.asyncio
+async def test_webrtc_stream_request_missing_file(sk_node, sk_hub, gek, shared_dir):
+    """WebRTC DataChannel: stream_request for non-existent file returns error."""
+    hub_pk_pem = _hub_pk_pem(sk_hub)
+    indexer = DirectoryIndexer(root=shared_dir, group_id="g", sk_node=sk_node, gek=gek)
+    await indexer.initial_scan()
+
+    transport = WebRTCTransport(
+        sk_node=sk_node, hub_pk_pem=hub_pk_pem, gek=gek,
+        shared_root=shared_dir, index=indexer.index,
+        stun_servers=[],
+    )
+
+    browser_pc = RTCPeerConnection()
+    received = asyncio.Queue()
+    buf = bytearray()
+
+    channel = browser_pc.createDataChannel("mnp")
+
+    @channel.on("open")
+    def on_open():
+        channel.send(_pack({
+            "type": MNP.HANDSHAKE, "v": MNP_VERSION,
+            "token": _make_jwt(sk_hub),
+        }))
+
+    @channel.on("message")
+    def on_msg(message):
+        if isinstance(message, str):
+            message = message.encode()
+        buf.extend(message)
+        while len(buf) >= 4:
+            length = struct.unpack(">I", buf[:4])[0]
+            if len(buf) < 4 + length:
+                break
+            msg_bytes = bytes(buf[4:4 + length])
+            del buf[:4 + length]
+            received.put_nowait(msgpack.unpackb(msg_bytes, raw=False))
+
+    offer = await browser_pc.createOffer()
+    await browser_pc.setLocalDescription(offer)
+    answer_sdp, _ = await transport.handle_offer(
+        browser_pc.localDescription.sdp, "peer-mse")
+    await browser_pc.setRemoteDescription(
+        RTCSessionDescription(sdp=answer_sdp, type="answer"))
+
+    ack = await asyncio.wait_for(received.get(), timeout=5.0)
+    assert ack["type"] == MNP.HANDSHAKE_ACK
+
+    channel.send(_pack({
+        "type": MNP.STREAM_REQUEST, "v": MNP_VERSION,
+        "file_id": "nonexistent-file-id",
+    }))
+
+    msg = await asyncio.wait_for(received.get(), timeout=5.0)
+    assert msg["type"] == "error"
+    assert "not found" in msg["detail"].lower()
+
+    await browser_pc.close()
+    await transport.close_all()