feat(node,hub): add Videos group app (poster grid, flat list, TMDB metadata)

Implements docs/mediacenter.md: a "Videos" group application built on the
existing files index rather than a separate catalogue. On the node side,
new indexer enrichment (technical probe, filename/season parsing, thumbnail
generation) runs per-file once an operator has chosen a video_root for the
group, plus a TMDB client for on-demand poster/metadata lookups (never
client-side, thumbnails delivered over the existing chunk path). On the hub
side, a new video-app.js renders a lazily-mounted poster grid or a
thumbnail-only flat list, with TMDB entirely optional per group.

Along the way: the global apps registry now drives Settings' default-tab
picker instead of a hardcoded list, and the video_root is configured from
group Settings (like uploads) rather than from Files, with the node
refusing to run any TMDB/thumbnail work until one is set.

Fixes several bugs found via live testing against a real library, notably
a race between two effects writing the same "image ready" state that could
leave a poster grid spinning forever on a same-tab revisit — see
mediacenter.md §5.4 for the full account of each one.

1 files changed, 159 insertions, 0 deletions

diff --git a/packages/meshbay-node/src/meshbay_node/tmdb.py b/packages/meshbay-node/src/meshbay_node/tmdb.py
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+"""
+TMDB (themoviedb.org) client for the Videos group app.
+
+Called only by the node, never by a client (docs/mediacenter.md §2): the
+node holds the one credential and makes the one request per unique title,
+shared by every member. Token resolution order (§5.5):
+
+  1. an operator-supplied token (roster.py group_settings, group_id="")
+  2. the MESHBAY_TMDB_DEFAULT_TOKEN environment variable
+  3. none — TMDB lookups are inert (callers get an empty result, never an
+     exception, so a node with no token configured just serves thumbnails)
+
+The real secret (whichever token resolves) never appears in source control:
+there is no literal fallback value in this file. See mediacenter.md's
+implementation notes on why a shipped default is a deployment concern, not
+a code concern.
+
+Results also come back in whatever language the operator configured
+(roster.py's `tmdb_language`, e.g. "fr-FR") — one language for the whole
+node, same reasoning as the token: one shared cache, not a per-viewer
+request. Omitted entirely when unset, which lets TMDB fall back to its own
+default (English) rather than this client guessing one.
+"""
+
+import difflib
+import logging
+import os
+import re
+
+import httpx
+
+from meshbay_node.roster import Roster
+
+log = logging.getLogger(__name__)
+
+_BASE_URL = "https://api.themoviedb.org/3/"
+_IMAGE_BASE = "https://image.tmdb.org/t/p/w500"
+_TIMEOUT = 10.0
+_DEFAULT_TOKEN_ENV = "MESHBAY_TMDB_DEFAULT_TOKEN"
+
+
+def _normalize(s: str) -> str:
+    s = s.lower()
+    s = re.sub(r"[^a-z0-9àâäéèêëïîôöùûüçñ ]+", " ", s)
+    return re.sub(r"\s+", " ", s).strip()
+
+
+def _best_match(query_title: str, results: list[dict], keys: tuple[str, ...]) -> tuple[dict | None, float]:
+    """
+    Trusts TMDB's own ranking (§3.3's last row — a locally-recomputed
+    re-rank picked a coincidentally-closer-looking wrong show once): only
+    the top result is considered. The similarity ratio is returned purely
+    as a confidence signal for the caller's fallback decision, never used
+    to pick a different candidate.
+    """
+    if not results:
+        return None, 0.0
+    top = results[0]
+    qn = _normalize(query_title)
+    best_ratio = 0.0
+    for k in keys:
+        val = top.get(k)
+        if val:
+            best_ratio = max(best_ratio, difflib.SequenceMatcher(None, qn, _normalize(str(val))).ratio())
+    return top, best_ratio
+
+
+class TmdbClient:
+    """One instance per node, holding the resolved token and an httpx client."""
+
+    def __init__(self, roster: Roster | None = None,
+                 transport: httpx.AsyncBaseTransport | None = None):
+        self._roster = roster
+        # `transport` is a test-only seam (httpx.MockTransport) — production
+        # callers never pass it, and httpx.AsyncClient defaults to real
+        # network I/O when it's None.
+        self._client = httpx.AsyncClient(timeout=_TIMEOUT, transport=transport)
+
+    async def close(self) -> None:
+        await self._client.aclose()
+
+    async def _resolve(self) -> tuple[bool, str | None, str | None]:
+        """Returns (enabled, token, language). token/language are None when unset."""
+        if self._roster is not None:
+            enabled, custom_token, language = await self._roster.tmdb_config()
+        else:
+            enabled, custom_token, language = True, None, None
+        token = custom_token or os.environ.get(_DEFAULT_TOKEN_ENV) or None
+        return enabled and bool(token), token, language
+
+    async def _get(self, path: str, params: dict) -> dict | None:
+        enabled, token, language = await self._resolve()
+        if not enabled:
+            return None
+        if language and "language" not in params:
+            params = {**params, "language": language}
+        try:
+            resp = await self._client.get(
+                _BASE_URL + path, params=params,
+                headers={"Authorization": f"Bearer {token}", "accept": "application/json"},
+            )
+            resp.raise_for_status()
+            return resp.json()
+        except httpx.HTTPError as e:
+            log.warning("TMDB request failed (%s): %s", path, e)
+            return None
+
+    @staticmethod
+    def poster_url(path: str | None) -> str | None:
+        return f"{_IMAGE_BASE}{path}" if path else None
+
+    async def fetch_image(self, url: str) -> bytes | None:
+        """Fetches a poster/backdrop image. Unauthenticated — image.tmdb.org needs no token."""
+        try:
+            resp = await self._client.get(url, timeout=_TIMEOUT)
+            resp.raise_for_status()
+            return resp.content
+        except httpx.HTTPError as e:
+            log.warning("TMDB image fetch failed (%s): %s", url, e)
+            return None
+
+    async def search_movie(self, title: str, year: int | None = None) -> tuple[dict | None, float]:
+        params = {"query": title, "include_adult": "false"}
+        if year:
+            params["year"] = year
+        data = await self._get("search/movie", params)
+        results = (data or {}).get("results", [])
+        return _best_match(title, results, ("title", "original_title"))
+
+    async def search_tv(self, title: str) -> tuple[dict | None, float]:
+        data = await self._get("search/tv", {"query": title})
+        results = (data or {}).get("results", [])
+        return _best_match(title, results, ("name", "original_name"))
+
+    async def tv_season(self, tmdb_id: str | int, season: int) -> dict | None:
+        return await self._get(f"tv/{tmdb_id}/season/{season}", {})
+
+    async def movie_details(self, tmdb_id: str | int, language: str | None = None) -> dict | None:
+        """
+        Full details, not the search result: search/movie doesn't return
+        `runtime` or genre names (only `genre_ids`) at all.
+
+        `language`, when given, overrides the configured one — used for the
+        English fallback fetch (§ below): TMDB itself doesn't fall back
+        server-side for an untranslated field, it just returns "" for it,
+        the same gap the TMDB website itself papers over client-side.
+        """
+        params = {"language": language} if language else {}
+        return await self._get(f"movie/{tmdb_id}", params)
+
+    async def tv_details(self, tmdb_id: str | int, language: str | None = None) -> dict | None:
+        params = {"language": language} if language else {}
+        return await self._get(f"tv/{tmdb_id}", params)
+
+    async def movie_credits(self, tmdb_id: str | int) -> dict | None:
+        return await self._get(f"movie/{tmdb_id}/credits", {})
+
+    async def tv_credits(self, tmdb_id: str | int) -> dict | None:
+        return await self._get(f"tv/{tmdb_id}/credits", {})