fix(node,client): query TMDB only once a language is chosen, in that languageHEADmain

TMDB fiches are fetched lazily, on browse, and the fetch used to run whatever
the moment it was first triggered — routinely before the operator had opened
settings and picked a language, so it queried in TMDB's English default. Then
the fiche was cached by tmdb_id alone, with no note of language and a 30-day
TTL, so switching to the intended language afterwards changed nothing: the
English fiche was served until it expired. The operator's only recourse was to
find and wipe the cache by hand (found live 2026-09-26: a whole library indexed
in English although "Français" had been chosen).

Two rules now, both there to make the first fetch the right language rather
than English-then-corrected, and to stop the doubled requests that eventually
get a node rate-limited:

- No language configured, no query. media_meta_req/season_meta_req answer
  confidence 0 and make no TMDB call while tmdb_language is unset; the fetch
  waits for the operator's choice, so the first (and only) query is in it.
  English is now a first-class choice (en-US), not the default of skipping the
  setting.
- Changing the language wipes the metadata cache (ops.set_tmdb_config), so the
  new language takes effect on an already-browsed library. The file->tmdb
  matches are language-independent and kept. The client refetches on the
  tmdb_config_ack that carries the new language, so the grid updates without a
  page reload.

docs/MESHBAY_DESIGN.md §9.7 states both rules; tests cover the gate and the
cache wipe, and two existing handler harnesses now declare a language.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

1 files changed, 20 insertions, 0 deletions

diff --git a/packages/meshbay-node/src/meshbay_node/ops/apps.py b/packages/meshbay-node/src/meshbay_node/ops/apps.py
index 0e4f6dd..fbd984d 100644
--- a/packages/meshbay-node/src/meshbay_node/ops/apps.py
+++ b/packages/meshbay-node/src/meshbay_node/ops/apps.py
@@ -53,6 +53,13 @@ async def set_tmdb_config(state: dict, token: str | None = None,
     `language`.
     """
     roster = _roster(state)
+    # Whether the *language* actually changes decides whether the cached
+    # fiches must go (below) — read the old value before overwriting it.
+    # "" (default/English) and None (unset) are the same language here.
+    language_changed = False
+    if language is not None:
+        _, old_language = await roster.tmdb_config()
+        language_changed = (language or None) != (old_language or None)
     await roster.set_tmdb_config(token, language, set_by=state.get("node_user_id", ""))
     # `token=None` means "leave whatever was there" (§ set_tmdb_config's own
     # docstring) — so the customized flag only changes when a value (a real
@@ -61,6 +68,19 @@ async def set_tmdb_config(state: dict, token: str | None = None,
         state["tmdb_token_customized"] = bool(token)
     if language is not None:
         state["tmdb_language"] = language
+    # A cached TMDB fiche is stored under its tmdb_id alone and carries no note
+    # of the language it was fetched in (there is only one node-wide language),
+    # so changing the language leaves every fiche stale for its 30-day TTL.
+    # Drop the metadata cache here so the next media_meta_req refetches in the
+    # new language — this is what makes the setting take on a library that was
+    # already browsed, instead of the operator having to find a cache to clear.
+    # The matches (file_tmdb) are language-independent and kept.
+    if language_changed:
+        media_cache = state.get("media_cache")
+        if media_cache is not None:
+            removed = await media_cache.clear_tmdb_metadata()
+            log.info("TMDB language changed to %s: cleared %d cached fiche(s)",
+                     language or "(default)", removed)
     log.info("TMDB config: custom_token=%s language=%s",
              bool(token), language or state.get("tmdb_language", ""))
     return {