feat(node,hub): season-specific overviews, manual TMDB match correction, and wizard polish

Two operator-facing fixes for a real 3-season show whose automatic TMDB
match was wrong at the show level: per-season overview/air_date tabs in the
detail modal (falling back to the show-level text when a season's own is
empty), and a "Fix match…" search-and-correct affordance that re-resolves
every file sharing the corrected show's display_title. New signed op
OP_TMDB_OVERRIDE and two read-only pairs (season_meta_req/resp,
tmdb_search_req/resp), MNP_VERSION 0.5 -> 0.6.

Also: the create-group wizard gets a spinning indexing indicator and an
app-selection step, group settings default the TMDB language to the
operator's own locale (never as a global default), and a file renamed
mid-session now re-triggers title parsing instead of being silently
skipped by the enrichment dedup guard.

Fixes two bugs found during this work: the search overlay's z-index lost
to the base video-overlay class and rendered invisibly, and season_meta's
own empty overview didn't fall back to the show-level one.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01LAmyXtc6dAADsH23ydXQpY

4 files changed, 598 insertions, 0 deletions

diff --git a/packages/meshbay-node/tests/test_rename_reenrichment.py b/packages/meshbay-node/tests/test_rename_reenrichment.py
new file mode 100644
index 0000000..87e0d1a
--- /dev/null
+++ b/packages/meshbay-node/tests/test_rename_reenrichment.py
@@ -0,0 +1,163 @@
+"""
+Bug found live, 2026-08-24: an episode file first named in French (its
+release folder mixed languages across seasons) was renamed by the operator
+to match its English-named siblings — but kept showing as its own
+separate poster-grid card, and its own row in Flat list, indefinitely.
+
+`_enriched_attempted` (daemon.py) exists so that enrichment's own
+field-fill (duration/thumb_hash/display_title/... landing back via
+`_on_enriched`) does not re-trigger itself forever — but it also silently
+blocked the *new* filename from ever being title-parsed at all, since the
+file's content (and so its id) is unchanged by a rename. A rename/move is
+exactly the case `_reenrich_renamed_video_entries` exists to detect: same
+id, but `name` or `path` differs from the version last broadcast.
+"""
+
+import asyncio
+
+import pytest
+from cryptography.hazmat.primitives.asymmetric.ed25519 import Ed25519PrivateKey
+
+from meshbay_common.crypto import generate_gek
+from meshbay_node.config import Config, HubConfig, NodeConfig, GroupConfig, KeystoreConfig
+from meshbay_node.daemon import NodeDaemon
+from meshbay_node.indexer import DirectoryIndexer
+
+from conftest import one_root
+
+pytestmark = pytest.mark.asyncio
+
+
+def _free_port() -> int:
+    import socket
+    with socket.socket() as s:
+        s.bind(("127.0.0.1", 0))
+        return s.getsockname()[1]
+
+
+class _StubRoster:
+    async def video_root(self, group_id):
+        return "shared"
+
+
+class _SpyEnricher:
+    """Records which file ids were actually (re-)scheduled, without
+    needing a real ffmpeg/ffprobe pipeline for this test."""
+
+    def __init__(self):
+        self.spawned = []
+
+    def spawn(self, entry, file_path, on_done):
+        self.spawned.append(entry.id)
+
+        async def _noop():
+            return None
+
+        return asyncio.ensure_future(_noop())
+
+
+async def test_a_renamed_file_gets_re_enriched(tmp_path):
+    group_id = "a" * 32
+    shared = tmp_path / "shared"
+    shared.mkdir()
+    old_path = shared / "la-guerre-des-mondes-s03e02.mkv"
+    old_path.write_bytes(b"not a real video, just needs to be indexed as one")
+
+    config = Config(
+        hub=HubConfig(url="http://localhost:9999", username="testuser"),
+        node=NodeConfig(quic_port=_free_port(), ui_port=_free_port()),
+        groups=[GroupConfig(
+            id=group_id, name="test-group", shared_dir=str(shared),
+            visibility="private", quic_port=29016,
+        )],
+        keystore=KeystoreConfig(path=tmp_path / "keystore.enc"),
+        data_dir=tmp_path / "data",
+    )
+    daemon = NodeDaemon(config)
+    daemon._broadcast_coalesce_secs = 0.01
+    daemon._enricher = _SpyEnricher()
+    daemon._roster = _StubRoster()
+
+    indexer = DirectoryIndexer(
+        roots=one_root(shared), group_id=group_id,
+        sk_node=Ed25519PrivateKey.generate(), gek=generate_gek(),
+        # reconcile() below calls this itself — the initial scan doesn't
+        # (see test_startup_scan_enrichment.py), so that first broadcast is
+        # still triggered manually, matching _bg_scan's real sequence.
+        on_change=daemon._on_index_change)
+    await indexer.initial_scan()
+    await daemon._on_index_change(indexer)
+    await asyncio.sleep(0.05)
+
+    entry = next(iter(indexer.index.entries))
+    file_id = entry.id
+    assert daemon._enricher.spawned == [file_id], (
+        "the file must be scheduled for enrichment once, under its original name")
+
+    new_path = shared / "war-of-the-worlds-s03e02.mkv"
+    old_path.rename(new_path)
+    changed = await indexer.reconcile()
+    assert changed, "the rename must actually be picked up by reconcile()"
+    # The re-broadcast is a fire-and-forget task chained behind the
+    # coalescing timer, itself scheduling another fire-and-forget task —
+    # poll rather than guess a single sleep long enough for both hops.
+    for _ in range(30):
+        if len(daemon._enricher.spawned) >= 2:
+            break
+        await asyncio.sleep(0.02)
+
+    renamed_entry = indexer.index.get_entry(file_id)
+    assert renamed_entry is not None
+    assert renamed_entry.name == "war-of-the-worlds-s03e02.mkv"
+    assert daemon._enricher.spawned == [file_id, file_id], (
+        "a rename must re-schedule enrichment for the same file id — "
+        "_enriched_attempted must not permanently block the new filename "
+        "from ever being title-parsed")
+
+
+async def test_an_unrelated_update_does_not_re_trigger_enrichment(tmp_path):
+    """
+    The other half of the same fix: an update whose name/path did *not*
+    change (the ordinary case — enrichment's own field-fill, or the
+    reconcile sweep confirming a file unmodified) must not re-schedule
+    enrichment. Without this, `_on_enriched` merging a file's own results
+    back into the index would count as its own trigger and loop forever.
+    """
+    group_id = "a" * 32
+    shared = tmp_path / "shared"
+    shared.mkdir()
+    path = shared / "movie.mkv"
+    path.write_bytes(b"not a real video, just needs to be indexed as one")
+
+    config = Config(
+        hub=HubConfig(url="http://localhost:9999", username="testuser"),
+        node=NodeConfig(quic_port=_free_port(), ui_port=_free_port()),
+        groups=[GroupConfig(
+            id=group_id, name="test-group", shared_dir=str(shared),
+            visibility="private", quic_port=29017,
+        )],
+        keystore=KeystoreConfig(path=tmp_path / "keystore.enc"),
+        data_dir=tmp_path / "data",
+    )
+    daemon = NodeDaemon(config)
+    daemon._broadcast_coalesce_secs = 0.01
+    daemon._enricher = _SpyEnricher()
+    daemon._roster = _StubRoster()
+
+    indexer = DirectoryIndexer(
+        roots=one_root(shared), group_id=group_id,
+        sk_node=Ed25519PrivateKey.generate(), gek=generate_gek(),
+        on_change=daemon._on_index_change)
+    await indexer.initial_scan()
+    await daemon._on_index_change(indexer)
+    await asyncio.sleep(0.05)
+
+    entry = next(iter(indexer.index.entries))
+    assert daemon._enricher.spawned == [entry.id]
+
+    # A reconcile pass that finds nothing changed at all — not even a
+    # rename — must not re-schedule anything.
+    changed = await indexer.reconcile()
+    await asyncio.sleep(0.05)
+    assert not changed
+    assert daemon._enricher.spawned == [entry.id]
diff --git a/packages/meshbay-node/tests/test_season_and_search_requests.py b/packages/meshbay-node/tests/test_season_and_search_requests.py
new file mode 100644
index 0000000..8ba55fb
--- /dev/null
+++ b/packages/meshbay-node/tests/test_season_and_search_requests.py
@@ -0,0 +1,187 @@
+"""
+`_do_season_meta_request` (per-season TMDB overview/poster/air_date, for the
+season-tab view — docs/mediacenter.md §5.4's fix for a 3-season show whose
+overview read as season-3-specific for every season) and
+`_do_tmdb_search_request` (raw TMDB candidates for an operator correcting a
+wrong automatic match). Neither is a signed admin op — see each handler's own
+docstring for why — so these tests only exercise the read path, unlike
+test_tmdb_override_policy.py.
+"""
+
+import pytest
+
+from meshbay_common.protocol import MNP
+from meshbay_node.media_cache import MediaCache
+from meshbay_node.transport.webrtc_server import WebRTCPeerSession
+
+pytestmark = pytest.mark.asyncio
+
+
+def _session(media_cache=None, tmdb_client=None) -> WebRTCPeerSession:
+    session = WebRTCPeerSession.__new__(WebRTCPeerSession)
+    session._ctx = {"media_cache": media_cache, "tmdb_client": tmdb_client}
+    session.sent = []
+    session._send = session.sent.append
+    return session
+
+
+@pytest.fixture
+async def media_cache(tmp_path):
+    c = MediaCache(db_path=tmp_path / "media_cache.db")
+    await c.open()
+    yield c
+    await c.close()
+
+
+class FakeTmdbClient:
+    def __init__(self, season_json=None):
+        self.season_json = season_json
+        self.tv_season_calls = []
+        self.movie_search_calls = []
+        self.tv_search_calls = []
+
+    @staticmethod
+    def poster_url(path):
+        return f"https://image.tmdb.org/t/p/w500{path}"
+
+    async def fetch_image(self, url):
+        return b"jpeg-bytes-for-" + url.encode()
+
+    async def tv_season(self, tmdb_id, season, language=None):
+        self.tv_season_calls.append((tmdb_id, season, language))
+        return self.season_json
+
+    async def search_movie_results(self, title):
+        self.movie_search_calls.append(title)
+        return [{"id": 111, "title": title, "release_date": "2019-05-01", "poster_path": "/m.jpg"}]
+
+    async def search_tv_results(self, title):
+        self.tv_search_calls.append(title)
+        return [{"id": 222, "name": title, "first_air_date": "2021-03-01", "poster_path": "/t.jpg"}]
+
+
+# ── season_meta_req ──────────────────────────────────────────────────────────
+
+async def test_season_meta_missing_tmdb_id_is_refused():
+    session = _session()
+    await session._do_season_meta_request({"season": 1})
+    assert session.sent == [{"type": "error", "detail": "Missing tmdb_id or season"}]
+
+
+async def test_season_meta_non_int_season_is_refused():
+    session = _session()
+    await session._do_season_meta_request({"tmdb_id": "42", "season": "1"})
+    assert session.sent == [{"type": "error", "detail": "Missing tmdb_id or season"}]
+
+
+async def test_season_meta_with_no_cache_or_client_reports_zero_confidence():
+    session = _session(media_cache=None, tmdb_client=None)
+    await session._do_season_meta_request({"tmdb_id": "42", "season": 1})
+    assert session.sent == [{
+        "type": MNP.SEASON_META_RESP, "v": session.sent[0]["v"],
+        "tmdb_id": "42", "season": 1, "confidence": 0,
+    }]
+
+
+async def test_season_meta_cache_hit_skips_the_tmdb_call(media_cache):
+    await media_cache.set_season_meta("42", 3, {
+        "name": "Season 3", "overview": "cached overview", "air_date": "2023-01-01",
+        "poster_path": "/cached.jpg",
+    })
+    client = FakeTmdbClient()
+    session = _session(media_cache=media_cache, tmdb_client=client)
+
+    await session._do_season_meta_request({"tmdb_id": "42", "season": 3})
+
+    assert client.tv_season_calls == [], "a cached season must not be re-fetched"
+    resp = session.sent[0]
+    assert resp["type"] == MNP.SEASON_META_RESP
+    assert resp["confidence"] == 1.0
+    assert resp["overview"] == "cached overview"
+
+
+async def test_season_meta_cache_miss_fetches_and_caches(media_cache):
+    client = FakeTmdbClient(season_json={
+        "name": "Season 1", "overview": "fresh overview", "air_date": "2020-01-01",
+        "poster_path": "/fresh.jpg",
+    })
+    session = _session(media_cache=media_cache, tmdb_client=client)
+
+    await session._do_season_meta_request({"tmdb_id": "7", "season": 1})
+
+    assert client.tv_season_calls == [("7", 1, None)]
+    resp = session.sent[0]
+    assert resp["overview"] == "fresh overview"
+    assert resp["poster_thumb_hash"] is not None
+    cached = await media_cache.get_season_meta("7", 1)
+    assert cached["overview"] == "fresh overview", "a fetched season must be cached for next time"
+
+
+async def test_season_meta_empty_overview_falls_back_to_english(media_cache):
+    async def tv_season(tmdb_id, season, language=None):
+        if language == "en-US":
+            return {"name": "S1", "overview": "English overview", "air_date": "2020-01-01",
+                    "poster_path": "/p.jpg"}
+        return {"name": "S1", "overview": "", "air_date": "2020-01-01", "poster_path": "/p.jpg"}
+
+    client = FakeTmdbClient()
+    client.tv_season = tv_season
+    session = _session(media_cache=media_cache, tmdb_client=client)
+
+    await session._do_season_meta_request({"tmdb_id": "9", "season": 1})
+
+    assert session.sent[0]["overview"] == "English overview"
+
+
+# ── tmdb_search_req ──────────────────────────────────────────────────────────
+
+async def test_search_missing_query_is_refused():
+    session = _session()
+    await session._do_tmdb_search_request({"media_type": "movie"})
+    assert session.sent == [{"type": "error", "detail": "Missing query or media_type"}]
+
+
+async def test_search_bad_media_type_is_refused():
+    session = _session()
+    await session._do_tmdb_search_request({"query": "war", "media_type": "album"})
+    assert session.sent == [{"type": "error", "detail": "Missing query or media_type"}]
+
+
+async def test_search_with_no_cache_or_client_returns_empty_results():
+    session = _session(media_cache=None, tmdb_client=None)
+    await session._do_tmdb_search_request({"query": "war", "media_type": "tv"})
+    assert session.sent == [{
+        "type": MNP.TMDB_SEARCH_RESP, "v": session.sent[0]["v"],
+        "query": "war", "media_type": "tv", "results": [],
+    }]
+
+
+async def test_search_movie_calls_movie_search_and_echoes_media_type(media_cache):
+    client = FakeTmdbClient()
+    session = _session(media_cache=media_cache, tmdb_client=client)
+
+    await session._do_tmdb_search_request({"query": "War of the Worlds", "media_type": "movie"})
+
+    assert client.movie_search_calls == ["War of the Worlds"]
+    assert client.tv_search_calls == []
+    resp = session.sent[0]
+    assert resp["type"] == MNP.TMDB_SEARCH_RESP
+    assert resp["media_type"] == "movie", (
+        "media_type must be echoed back — otherwise a movie search and a tv "
+        "search for the same query are indistinguishable to the client's "
+        "keyed response matching (transport.js tmdb_search_resp handler)")
+    assert resp["results"] == [{
+        "tmdb_id": "111", "title": "War of the Worlds", "year": "2019",
+        "poster_thumb_hash": resp["results"][0]["poster_thumb_hash"],
+    }]
+
+
+async def test_search_tv_calls_tv_search(media_cache):
+    client = FakeTmdbClient()
+    session = _session(media_cache=media_cache, tmdb_client=client)
+
+    await session._do_tmdb_search_request({"query": "War of the Worlds", "media_type": "tv"})
+
+    assert client.tv_search_calls == ["War of the Worlds"]
+    assert client.movie_search_calls == []
+    assert session.sent[0]["media_type"] == "tv"
diff --git a/packages/meshbay-node/tests/test_tmdb_override_policy.py b/packages/meshbay-node/tests/test_tmdb_override_policy.py
new file mode 100644
index 0000000..b8fa6f9
--- /dev/null
+++ b/packages/meshbay-node/tests/test_tmdb_override_policy.py
@@ -0,0 +1,172 @@
+"""
+An operator correcting a wrong automatic TMDB match (found live: a real
+show's search consistently matched a season-3-specific promotional TMDB
+entry instead of the show itself). Signed like video_root/tmdb_config —
+it changes what every member sees, node-wide (media_cache is shared, not
+per-viewer) — and, once authorized, applies to every index entry sharing
+the representative file's display_title, the same grouping the poster
+grid itself uses (§3.4/§V6), not just the one file the operator happened
+to be looking at.
+"""
+
+import hashlib
+from pathlib import Path
+
+import pytest
+from cryptography.hazmat.primitives.asymmetric.ed25519 import Ed25519PrivateKey
+
+from meshbay_common.adminop import OP_TMDB_OVERRIDE
+from meshbay_common.protocol import IndexEntry, MNP
+from meshbay_node.indexer.group_index import GroupIndex
+from meshbay_node.media_cache import MediaCache
+from meshbay_node.transport.webrtc_server import WebRTCPeerSession
+
+from conftest import one_root
+
+pytestmark = pytest.mark.asyncio
+
+
+def _session(tmp_path: Path, user_id: str, *, operator: str | None = None) -> WebRTCPeerSession:
+    shared_root = tmp_path / "shared"
+    shared_root.mkdir(exist_ok=True)
+    index = GroupIndex(group_id="g" * 32, sk_node=Ed25519PrivateKey.generate())
+    ctx = {
+        "roots": one_root(shared_root),
+        "index": index,
+        "sk_node": index.sk_node,
+        "node_user_id": operator,
+    }
+    session = WebRTCPeerSession.__new__(WebRTCPeerSession)
+    session._ctx = ctx
+    session._group_id = None
+    session._user_id = user_id
+    session._pk_user = ""
+    session.sent = []
+    session._send = session.sent.append
+    session._audit = lambda *a, **k: None
+    return session
+
+
+def _entry(path: str, name: str, display_title: str) -> IndexEntry:
+    # A real id is a blake3 content hash; sha256 here is just a stand-in with
+    # the same property that matters for these tests — deterministic and
+    # effectively collision-free across the handful of entries a test builds.
+    # (`hash((path, name)) % 10` was tried here before and is NOT that: it's
+    # randomized per-process by PYTHONHASHSEED and collides constantly across
+    # only 10 possible values, silently dropping entries in GroupIndex's
+    # id-keyed dict.)
+    digest = hashlib.sha256(f"{path}/{name}".encode()).hexdigest()
+    return IndexEntry(
+        id=digest, name=name, path=path,
+        size=1, type="video", added_at=0, display_title=display_title,
+        season=1, episode=1,
+    )
+
+
+# ── Refused before a challenge is even issued ───────────────────────────────
+
+async def test_missing_path_is_refused(tmp_path):
+    session = _session(tmp_path, "op", operator="op")
+    session._has_admin_authority = lambda: True
+    issued = []
+    session._issue_admin_challenge = lambda op, subject: issued.append((op, subject))
+
+    session._do_tmdb_override({"tmdb_id": "123", "media_type": "tv"})
+
+    assert not issued
+    assert [m for m in session.sent if m.get("type") == "error"]
+
+
+async def test_missing_tmdb_id_is_refused(tmp_path):
+    session = _session(tmp_path, "op", operator="op")
+    session._ctx["index"].add_entry(_entry("shared", "ep.mkv", "Show"))
+    session._has_admin_authority = lambda: True
+    issued = []
+    session._issue_admin_challenge = lambda op, subject: issued.append((op, subject))
+
+    session._do_tmdb_override({"path": "shared", "media_type": "tv"})
+
+    assert not issued
+    assert [m for m in session.sent if m.get("type") == "error"]
+
+
+async def test_unknown_path_is_refused(tmp_path):
+    session = _session(tmp_path, "op", operator="op")
+    session._has_admin_authority = lambda: True
+    issued = []
+    session._issue_admin_challenge = lambda op, subject: issued.append((op, subject))
+
+    session._do_tmdb_override({"path": "nope", "tmdb_id": "123", "media_type": "tv"})
+
+    assert not issued
+    assert [m for m in session.sent if m.get("type") == "error"]
+
+
+async def test_a_request_with_nobody_to_authorize_it_is_refused(tmp_path):
+    session = _session(tmp_path, "member-1", operator="the-operator")
+    session._ctx["index"].add_entry(_entry("shared", "ep.mkv", "Show"))
+    session._has_admin_authority = lambda: False
+
+    session._do_tmdb_override({"path": "shared", "tmdb_id": "123", "media_type": "tv"})
+
+    assert [m for m in session.sent if m.get("type") == "error"]
+
+
+async def test_a_valid_request_is_signed(tmp_path):
+    session = _session(tmp_path, "op", operator="op")
+    session._ctx["index"].add_entry(_entry("shared", "ep.mkv", "War of the Worlds"))
+    session._has_admin_authority = lambda: True
+    issued = []
+    session._issue_admin_challenge = lambda op, subject: issued.append((op, subject))
+
+    session._do_tmdb_override({"path": "shared", "tmdb_id": "2255", "media_type": "tv"})
+
+    assert issued == [(OP_TMDB_OVERRIDE,
+                       "path=shared,tmdb_id=2255,media_type=tv")]
+
+
+# ── Applying the override ───────────────────────────────────────────────────
+
+async def test_override_updates_every_entry_sharing_the_display_title(tmp_path):
+    session = _session(tmp_path, "op", operator="op")
+    index = session._ctx["index"]
+    s1 = _entry("shared/S1", "s01e01.mkv", "War of the Worlds")
+    s2 = _entry("shared/S2", "s02e01.mkv", "War of the Worlds")
+    s3 = _entry("shared/S3", "s03e02.mkv", "War of the Worlds")
+    other_show = _entry("shared/Other", "ep.mkv", "A Different Show")
+    for e in (s1, s2, s3, other_show):
+        index.add_entry(e)
+
+    media_cache = MediaCache(db_path=tmp_path / "media_cache.db")
+    await media_cache.open()
+    try:
+        session._ctx["media_cache"] = media_cache
+        # Signature verification itself is exercised generically elsewhere
+        # (test_roster_pairing.py) — this test is about the policy once a
+        # signature is known good: which entries actually get updated, and
+        # who is told about it.
+        session._verify_admin_sig = lambda transcript, sig: _true()
+        peer = type("Peer", (), {"sent": []})()
+        peer._send = peer.sent.append
+        session._peer_registry = lambda: {"peer-1": peer}
+
+        await session._admin_exec_tmdb_override(
+            {"subject": "path=shared/S1,tmdb_id=999,media_type=tv"},
+            b"transcript", b"sig")
+
+        for e in (s1, s2, s3):
+            assert await media_cache.get_file_tmdb(e.id) == ("999", "tv"), (
+                "every entry sharing the representative file's display_title "
+                "must be corrected, not just the one the operator clicked on")
+        assert await media_cache.get_file_tmdb(other_show.id) is None, (
+            "a different show's own match must be left alone")
+        # The ack is broadcast to other connected peers, never echoed onto
+        # the requester's own `sent` — see the loop in
+        # _admin_exec_tmdb_override, which sends via each peer's own _send.
+        assert [m for m in peer.sent if m.get("type") == MNP.TMDB_OVERRIDE_ACK]
+    finally:
+        await media_cache.close()
+
+
+async def _true():
+    return True
diff --git a/packages/meshbay-node/tests/test_wizard_apps_endpoint.py b/packages/meshbay-node/tests/test_wizard_apps_endpoint.py
new file mode 100644
index 0000000..10ab489
--- /dev/null
+++ b/packages/meshbay-node/tests/test_wizard_apps_endpoint.py
@@ -0,0 +1,76 @@
+"""
+Create Group wizard: choosing which apps a brand-new group offers, before
+the (potentially long) initial scan — see app.js's CreateGroupWizard. This
+is a loopback-only, operator-authenticated endpoint (11.5.3), same shape as
+the existing member-upload one: a thin adapter over `ops.set_enabled_apps`,
+with only the validation `_do_apps_enabled` (the signed MNP front door)
+already does client-side in the wizard, but worth enforcing at this front
+door too since nothing else would.
+"""
+
+from pathlib import Path
+
+import pytest
+from cryptography.hazmat.primitives.asymmetric.ed25519 import Ed25519PrivateKey
+from fastapi.testclient import TestClient
+
+from conftest import one_root
+from meshbay_node.indexer.group_index import GroupIndex
+from meshbay_node.roster import Roster
+from meshbay_node.ui.app import create_ui_app
+
+pytestmark = pytest.mark.asyncio
+
+
+async def _client(tmp_path: Path):
+    shared = tmp_path / "shared"
+    shared.mkdir(exist_ok=True)
+    index = GroupIndex(group_id="g" * 32, sk_node=Ed25519PrivateKey.generate())
+    roster = Roster(db_path=tmp_path / "roster.db")
+    await roster.open()
+    state = {
+        "status": "running",
+        "groups_ctx": {"g" * 32: {"index": index, "roots": one_root(shared)}},
+        "indexes": {"g" * 32: index},
+        "roster": roster,
+    }
+    app = create_ui_app(state)
+    return TestClient(app), roster
+
+
+async def test_narrowing_the_apps_persists_to_the_roster(tmp_path):
+    client, roster = await _client(tmp_path)
+    try:
+        resp = client.put(f"/api/groups/{'g' * 32}/apps", json={"apps": ["files", "video"]})
+        assert resp.status_code == 200, resp.text
+        assert sorted(resp.json()["apps"]) == ["files", "video"]
+        assert sorted(await roster.enabled_apps("g" * 32)) == ["files", "video"]
+    finally:
+        await roster.close()
+
+
+async def test_empty_apps_list_is_refused(tmp_path):
+    client, roster = await _client(tmp_path)
+    try:
+        resp = client.put(f"/api/groups/{'g' * 32}/apps", json={"apps": []})
+        assert resp.status_code == 400
+    finally:
+        await roster.close()
+
+
+async def test_missing_apps_field_is_refused(tmp_path):
+    client, roster = await _client(tmp_path)
+    try:
+        resp = client.put(f"/api/groups/{'g' * 32}/apps", json={})
+        assert resp.status_code == 400
+    finally:
+        await roster.close()
+
+
+async def test_unhosted_group_is_refused(tmp_path):
+    client, roster = await _client(tmp_path)
+    try:
+        resp = client.put("/api/groups/" + "z" * 32 + "/apps", json={"apps": ["files"]})
+        assert resp.status_code == 404
+    finally:
+        await roster.close()