Pass per-stem name/description through to the stems payloads (#1013)

feedpak 1.16.0 (spec §5.3) added two OPTIONAL presentational fields to a
stems[] entry: `name` (display label, Readers fall back to the id) and
`description` (free text). The server dropped both while normalizing
manifest stems, so no client could ever display them.

Pass them through at the one place stem descriptors are built
(sloppak.load_song) and let both payload builders — the WS `ready` stems
list and the REST `/api/song/{f}?stems=1` preload list, which are pinned
against each other by test — carry them forward. Omit-when-absent, so a
stem without the fields does not grow null keys; non-string or blank
values are dropped rather than surfaced.

No behaviour change for existing packs or clients: the fields are
additive and every consumer that reads {id,url,default} keeps working
unchanged. The stems plugin / stem mixer display work lands separately.

Signed-off-by: topkoa <topkoa@gmail.com>
Co-authored-by: Claude Fable 5 <noreply@anthropic.com>

lib/routers/song.py

@@ -868,7 +868,8 @@ def _playable_stems_payload(filename: str, dlc) -> dict:
 
     return {
         "stems": [
-            {"id": s["id"], "url": _url(s["file"]), "default": s["default"]}
+            {"id": s["id"], "url": _url(s["file"]), "default": s["default"],
+             **{k: s[k] for k in ("name", "description") if k in s}}
             for s in loaded.stems
         ],
         "full_mix_url": _url(loaded.full_mix) if loaded.full_mix else None,

lib/routers/ws_highway.py

@@ -368,7 +368,9 @@ async def highway_ws(websocket: WebSocket, filename: str, arrangement: int = -1,
             q_fn = quote(filename, safe="")
             for s in loaded_slop.stems:
                 url = f"/api/sloppak/{q_fn}/file/{quote(s['file'])}"
-                stems_payload.append({"id": s["id"], "url": url, "default": s["default"]})
+                stems_payload.append(
+                    {"id": s["id"], "url": url, "default": s["default"],
+                     **{k: s[k] for k in ("name", "description") if k in s}})
             # Full-mix URL (served by the same /api/sloppak/.../file/ endpoint).
             if loaded_slop is not None and loaded_slop.full_mix:
                 full_mix_url = (

lib/sloppak.py

@@ -1114,11 +1114,19 @@ def load_song(
         sfile = str(s.get("file", ""))
         if not sid or not sfile:
             continue
-        stems.append({
+        entry = {
             "id": sid,
             "file": sfile,
             "default": stem_default_on(s.get("default", True)),
-        })
+        }
+        # Optional presentational fields (feedpak 1.16.0, spec §5.3). Omitted —
+        # not None — when absent, so payload builders can pass entries through
+        # without every stem growing null keys.
+        for key in ("name", "description"):
+            val = s.get(key)
+            if isinstance(val, str) and val.strip():
+                entry[key] = val
+        stems.append(entry)
 
     # The complete mixdown is a stem (spec §5.3), but it is not a *layer*: lift
     # it out so that no consumer of `stems` — the mixer, the library's stem