fix(xtream): guard conflicted favorites and explicit replacements

docs/architecture/portal-detail-navigation.md

@@ -94,7 +94,9 @@ handler as the header Back.
   so the correct detail host still opens without switching playlist context.
 - Dashboard `Global Favorites` and `Recently Watched` widgets hand off Xtream and
   Stalker movies/series into the matching global collection route with detail
-  pre-opened.
+  pre-opened. Unavailable favorites instead open the all-playlists collection
+  filtered to that content type, with no detail handoff, so an active different
+  playlist cannot hide the saved entry.
 - The dashboard hero CTA and the Continue Watching cards' explicit "Resume
   episode" ⋮ action for Xtream and Stalker series carry a one-shot
   season/episode resume target. The collection-owned detail consumes it after

docs/architecture/xtream-portal-compatibility.md

@@ -110,6 +110,16 @@ Favorites and Recent reads/writes share this resolution. Recent/detail backdrop
 writes check the actual catalog evidence, never the resolved collection row
 which already carries saved identity. Browsing, reload and re-export therefore
 cannot replace an imported snapshot merely because a provider reused its ID.
+A known browser identity conflict marks the retained snapshot unavailable, so
+collection and dashboard detail actions cannot open the replacement under the
+saved title. This survives reload and clears only when the saved identity is
+confirmed again. Explicit removal remains available. After removal, deliberately
+favoriting the current item may replace the old snapshot (including legacy key
+aliases); that replacement must persist before the new reference is saved, so
+storage failure cannot silently resurrect the old title. Ordinary optional
+snapshot-cache writes retain their existing quota behavior. The explicit browser
+favorite writer loads on demand; after loading, reference and snapshot writes
+run synchronously against fresh storage so concurrent additions are not lost.
 Initial browser imports and deferred retries share `PwaXtreamBackupStorage`;
 `PwaXtreamBackupStateService` supplies its injected storage for the importer.
 Both write the lists first and require the nested favorite snapshots to persist