fix(webui): persist markdown video previews

tests/channels/test_websocket_media_route.py

@@ -155,6 +155,28 @@ def test_local_markdown_image_is_staged_and_rewritten(
     assert staged[0].read_bytes() == _PNG_BYTES
 
 
+def test_local_markdown_video_is_staged_and_rewritten(
+    bus: MagicMock,
+    tmp_path: Path,
+) -> None:
+    workspace = tmp_path / "workspace"
+    workspace.mkdir()
+    video_bytes = b"fake mp4"
+    (workspace / "nanobot-intro.mp4").write_bytes(video_bytes)
+    media = tmp_path / "media"
+    channel = _ch(bus, workspace_path=workspace, port=0)
+
+    with patch("nanobot.channels.websocket.get_media_dir", side_effect=_fake_media_dir(media)):
+        rewritten = channel._rewrite_local_markdown_images(
+            "The result:\n![nanobot-intro.mp4](nanobot-intro.mp4)"
+        )
+
+    assert "![nanobot-intro.mp4](/api/media/" in rewritten
+    staged = list((media / "websocket").iterdir())
+    assert len(staged) == 1
+    assert staged[0].read_bytes() == video_bytes
+
+
 def test_local_markdown_image_rejects_workspace_escape(
     bus: MagicMock,
     tmp_path: Path,

tests/utils/test_webui_transcript.py

@@ -66,6 +66,24 @@ def test_replay_uses_stream_end_final_text() -> None:
     assert msgs[1]["content"] == "![Diagram](/api/media/sig/payload)"
 
 
+def test_replay_infers_video_media_from_attachment_name() -> None:
+    msgs = replay_transcript_to_ui_messages(
+        [
+            {"event": "user", "chat_id": "t-video", "text": "render"},
+            {
+                "event": "message",
+                "chat_id": "t-video",
+                "text": "video ready",
+                "media_urls": [{"url": "/api/media/sig/payload", "name": "intro.mp4"}],
+            },
+        ],
+    )
+
+    assert msgs[1]["media"] == [
+        {"kind": "video", "url": "/api/media/sig/payload", "name": "intro.mp4"},
+    ]
+
+
 def test_replay_file_edit_event_creates_file_activity(tmp_path, monkeypatch) -> None:
     monkeypatch.setattr("nanobot.config.paths.get_data_dir", lambda: tmp_path)
     key = "websocket:t-file"