Fix mixed-deck Nexus Betrayal continuations

docs/NEXUS_CARD_RULES.md

@@ -856,6 +856,28 @@ new collect action or played-game conversion is added. Existing supported
 ordinary module/native envelopes now inherit the same normal band; no new
 combination is admitted. [Current activation and limits](SPICE_BANKER_RUNTIME.md#mandatory-ordinary-skills-default--17-october-2026).
 
+## Basic mixed-deck Nexus reactions — 30 October 2026
+
+**Prototyped / Partial.** Supported public selected-deck Nexus starts can
+contain native Ixians, Harkonnen and Richese. Ixian Betrayal now validates
+the selected Ix/CHOAM/Ecaz deck and the separate Richese cache even without
+the independent Ecaz card variant. Basic Harkonnen Betrayal validates the
+selected physical cards, native leader Traitors and the Ix Cheap Hero Traitor.
+The existing provisional counter and neutral acknowledgement ordering applies.
+An owed Harkonnen replacement remains pending through the initial Ix
+phase-opening window and is drawn once when Mentat actually begins. Advanced
+selected-deck Harkonnen reactions remain unfinished: their original traitor
+calls continue without this Nexus interruption. Starts that never initialized
+the reaction still retain their existing boundary.
+
+Public-start journeys use genuine setup, worm, Nexus draw, Ixian auction and
+Harkonnen battle; unopened deck order and, for battle, a conserved traitor
+transfer and force placement are staged. Pure helper tests additionally cover
+the Cheap Hero identity. Other rosters, nested effects, complete games and
+deployed acceptance remain open. Public Semuta/Nexus activation is deferred
+because the marker currently suppresses existing Emperor Nexus effects and
+Sapho order; the separate audit initializer is unchanged.
+
 ## Semuta with original native Nexus — 11 October 2026
 
 Fresh `semuta --nexus-cards` composes native Richese with the original