Prototype CHOAM Nexus Collection trade and inventory Discoveries

An unallied player holding CHOAM Nexus while CHOAM is absent can now discard one Worthless card during Spice Collection for two bank spice. The server spends both physical cards once, exposes only private legal card choices, and persists an already-paid discard receipt. Human controls and all four AI profiles share the action. The after-victory inspection alternative remains missing; normal unfinished modes and publication stay gated.

Independent review caught and fixed a queued Grumman Collection lock mismatch. Focused tests cover Basic/Advanced, actual card custody, private controls, all AI profiles, stale and wrong-mode rejection, Truthtrance and Grumman locks, JSON corruption/replay, competing production SQLite writes and private seat restoration.

A separate bounded acquisition helper recorded all seven Discovery Spice Cards, eight tokens and exact physical card placements from publisher-authored sources. Discovery runtime remains missing.

Validation: types, lint, 4,217 offline tests, production build and 40 HTTP tests passed. Durations: check 139298 ms; build 6617 ms; HTTP 24329 ms. Source fingerprint dfdaaf8bafe69acd31c9d0afc13f7a0d070da43deb544f091e95fe840b399493; private report under ~/.local/share/dune/checkpoints/20260913-choam-nexus-trade/verification/report.json. Browser reference search, Prototyped label and related Collection link checked. All 95 opening saved rooms unchanged; 30 HTTP test rooms added, 125 total. No server restart or database reset.

Efficiency counter: 59,982,405 at batch start; 60,581,959 after broad verification, delta 599,554 aggregate tokens before final preservation/Git/usage checks. One newly playable function plus the acquired Discovery inventory; this is not full CHOAM or Nexus compliance.

docs/RULE_DECISIONS.md

@@ -14,6 +14,7 @@ Updated 13 September 2026. This is the authoritative navigation index for existi
 | Nexus lifecycle | Twelve physical cards, phase draw/replacement and alliance forfeiture; native Cunning, absent-faction Secret Ally and Betrayal have separate effects. No blanket Karama immunity. | [Common source contract](NEXUS_CARD_RULES.md), [lifecycle runtime](NEXUS_CARD_RUNTIME.md) |
 | Nexus faction effects | Preserve physical custody, original faction identity and durable effect receipts; use each printed family instead of borrowing another faction's rules by analogy. | [Atreides](NEXUS_ATREIDES_RULES.md), [Harkonnen](NEXUS_HARKONNEN_RULES.md), [BG](NEXUS_BENE_GESSERIT_RULES.md), [Emperor](NEXUS_EMPEROR_RULES.md), [Fremen](NEXUS_FREMEN_RULES.md), [Guild](NEXUS_GUILD_RULES.md) |
 | Expansion Nexus families | Source audit coverage does not imply every panel is playable; consult later runtime records in the status log. | [Ixian Cunning](NEXUS_IXIAN_CUNNING_RULES.md), [Ixian replacement](NEXUS_IXIAN_REPLACEMENT_RULES.md), [Tleilaxu](NEXUS_TLEILAXU_RULES.md), [CHOAM](NEXUS_CHOAM_RULES.md), [Richese](NEXUS_RICHESE_RULES.md), [Ecaz](NEXUS_ECAZ_RULES.md), [Moritani](NEXUS_MORITANI_RULES.md) |
+| CHOAM Secret Ally | Absent-faction Collection trade spends one actual Worthless card and the Nexus for two bank spice. It is separate from native Cunning and Auditor; the battle inspection alternative remains missing. | [Prototype contract](NEXUS_CHOAM_SECRET_ALLY.md) |
 | Guild Secret Ally | One explicit Guild-priced ordinary shipment; borrowed prices/routes preserve native identity. Free Fremen reinforcement remains a separate choice. | [Route contract](NEXUS_GUILD_SECRET_ALLY_RULES.md), [verified runtime](NEXUS_GUILD_SECRET_ALLY_RUNTIME.md) |
 | Homeworld custody and mobility | Physical home/visitor groups, population thresholds, tariffs and transport permissions retain distinct sources; Homeworld immunity is not universal immunity. | [Homeworld rules](HOMEWORLD_RULES.md), [benefits](HOMEWORLD_BENEFITS_RULES.md), [mobility](HOMEWORLD_MOBILITY_RULES.md), [invasion](HOMEWORLD_INVASION_RULES.md), [Guild transport](GUILD_HOMEWORLD_TRANSPORT_RULES.md) |
 | Homeworld effects | Keep original payment/revival/placement identities and qualification observations; observations alone do not choose an occupied-benefit owner. | [Payments](HOMEWORLD_PAYMENT_INCOME_RULES.md), [card economy](HOMEWORLD_CARD_ECONOMY_RULES.md), [Collection](HOMEWORLD_COLLECTION_RULES.md), [revival deployment](HOMEWORLD_REVIVAL_DEPLOYMENT_RULES.md), [victory reinforcement](HOMEWORLD_VICTORY_REINFORCEMENT_RULES.md), [replacement](HOMEWORLD_REPLACEMENT_RULES.md), [Tupile](HOMEWORLD_TUPILE_INTELLIGENCE_RULES.md) |