Add Nexus alliance and shared-victory practice

Expand the internal introduction to nine lessons and seven Basic exercises. The four-player Nexus example teaches incoming consent, outgoing accepted and unanswered offers, withdrawal, unilateral breaks and the ordinary three-solo/four-allied stronghold target. Formation shows prospective progress; victory appears only at an explicit later Mentat check on the unchanged teaching board. Fixed responses demonstrate legal choices without refining live AI.

Extract ordinary pairing into quoteNexusAlliance used by both practice and engine. Keep phase and Homeworld checks, alliance dates, Nexus-card forfeiture, readiness and history in the authoritative engine. Use production strongholdProgress and quoteVictory for the example; physical forces remain separately owned. No mode, expansion or publication gate changes.

Version 4 practice saves migrate all five v1, seven v2 and eight v3 lesson identities and preserve prior auction, movement, combat, Traitor and collection choices. Alliance inputs are whitelisted and semantically replayed, with impossible action sequences and phase order rejected. Nine new regression tests cover helper immutability, live engine side effects, all 24 offered practice combinations, prior-version migration and saved continuation. Existing Nexus-card forfeiture tests also pass.

Independent review found no material defect. Required types, lint, 4934 offline tests and production build pass on stable final source. Browser checks confirm old completed-auction migration, keyboard consent, formed and pending refresh restoration, withdrawal/break, closed-Nexus controls, three-stronghold shortfall and four-stronghold joint win with saved result. Controls fit a 390px viewport at 309px wide and at least44px high; viewport reset. No external lesson links. Screenshot capture remains unavailable, so visual screenshot acceptance remains unverified. Fixed lessons do not certify the full curriculum, live AI strength or all rules interactions.

The local development server was confirmed stopped by refused localhost connection and no matching processes. Started it once against the existing database without migration/reset. The existing K2V47CSN QA seat restored in setup with owning Atreides private hand/Traitors and rival privacy intact; its Hard Guild and circle6 remained visible. All 1337 rooms, 2805 seats and every original recovery/entry/handover/delegation/migration row are unchanged. SQLite integrity and foreign keys pass. No human play was interrupted, no recurring automation installed and no usage check or AI calibration run. HTTP/auth/schema source did not change; offline checks include recovery tests, and no broad HTTP suite was rerun.

Private evidence: 20260921-alliance-practice. Full rules, expansion, multiplayer and presentation goal remains incomplete.
Verified source tree: 9c74a3141aca4e049e0734209b96f68ee0e6d0e127a155a2a7562a79ea8a1a6b

docs/CURRENT_STATUS.md

@@ -1,27 +1,27 @@
 # Current development status
 
-Updated 20 September 2026. **The full twelve-faction goal is unfinished. Basic
+Updated 21 September 2026. **The full twelve-faction goal is unfinished. Basic
 is playable; public Advanced and unfinished expansion/module starts remain
 gated.** Prototypes do not open completion or publication gates.
 
 ## Current checkpoint and work
 
-Latest delivered checkpoint: `b9718ac`, [lobby AI configuration](LOBBY_AI_CONFIGURATION.md).
-Types, lint, **4,916 offline tests**, production build and **46 HTTP tests** passed.
-All 1,262 baseline rooms and 2,644 seats stayed unchanged; the new preservation
-baseline contains 1,337 rooms and 2,805 seats. No restart was needed.
-The preceding `b21b2bc` connects [one-use AI permission](SEAT_AI_PERMISSION.md).
-The `8f7a62c` policy checkpoint removed the
-usage cutoff and deferred AI refinement until feature completion, with three
-adjacent 75% win-rate targets. Earlier evidence remains in the
-[implementation history](IMPLEMENTATION_STATUS.md).
+Latest delivered checkpoint: `b7ec940`, [interactive bidding](INTERACTIVE_INTRODUCTION.md).
+Types, lint, **4,925 offline tests** and production build passed. All 1,337 rooms,
+2,805 seats and existing recovery/entry/handover/delegation rows stayed unchanged.
+The preceding `b9718ac` connects [lobby AI configuration](LOBBY_AI_CONFIGURATION.md)
+and `b21b2bc` connects [one-use AI permission](SEAT_AI_PERMISSION.md).
+The `8f7a62c` policy checkpoint removed the usage cutoff and deferred AI refinement
+until feature completion, with three adjacent 75% win-rate targets. Earlier
+evidence remains in the [implementation history](IMPLEMENTATION_STATUS.md).
 
-Current work: [interactive bidding](INTERACTIVE_INTRODUCTION.md) connects the
-eighth lesson to shared ordinary-auction calculations, private purchase inspection
-and versioned saved practice. No AI strategy is changed. Independent review and
-final browser/check/build/preservation evidence belong to the source-bound private
-report and Git message. Alliances, faction/Advanced/expansion teaching and broader
-disconnected-seat acceptance remain unfinished.
+Current work: [interactive alliance practice](INTERACTIVE_INTRODUCTION.md) adds
+the ninth lesson, ordinary Nexus consent/break choices and later shared stronghold
+victory through production quotes. Versioned practice migrates all earlier lesson
+positions and choices. No AI strategy is changed. Final independent review,
+browser/check/build/preservation and Git evidence belong to its private report.
+Alliance powers, faction/Advanced/expansion teaching and broader disconnected-seat
+acceptance remain unfinished.
 
 A bounded remaining-effect audit found that the reviewed faction/Nexus candidates
 still cross recorded pending rulings. Continue independent features rather than

docs/IMPLEMENTATION_STATUS.md

@@ -1,5 +1,18 @@
 # Dune implementation status
 
+## 21 September 2026 — Interactive Nexus alliance practice
+
+The [introduction](INTERACTIVE_INTRODUCTION.md) now connects nine lessons and seven
+Basic examples. A four-player Nexus teaches mutual consent, unanswered offers,
+withdrawal and unilateral alliance breaks. An explicit later Mentat check contrasts
+three shared strongholds with the ordinary four-stronghold joint victory. Shared
+production pairing, progress and victory quotes preserve physical force ownership.
+The live engine retains phase/expansion checks and card forfeiture. Version 4
+practice saves preserve all prior lesson identities and committed choices.
+Focused engine comparisons, migration and rejection checks accompany independent
+review and final source-bound browser/check/build/preservation/Git evidence in the
+private checkpoint. Broader teaching and all mode/publication gates remain open work.
+
 ## 20 September 2026 — Interactive ordinary bidding practice
 
 The [introduction](INTERACTIVE_INTRODUCTION.md) now connects eight lessons and six

docs/INTERACTIVE_INTRODUCTION.md

@@ -1,12 +1,12 @@
 # Interactive introduction
 
-20 September 2026. **Prototyped; partial teaching coverage.** `/learn` is linked
+21 September 2026. **Prototyped; partial teaching coverage.** `/learn` is linked
 from the lobby and rules reference. It adds the previously missing guided
 introduction alongside the reference's existing standalone practice wheel.
 
-Eight navigable lessons cover public/private table information and the phase
-sequence, bidding, shipment budgets, movement, sealed battle plans, Traitor calls, spice
-collection and joining or recovering a saved table. Six independent Basic practice positions let a player
+Nine navigable lessons cover public/private table information and the phase
+sequence, ordinary Nexus alliances, bidding, shipment budgets, movement, sealed battle plans, Traitor calls, spice
+collection and joining or recovering a saved table. Seven independent Basic practice positions let a player
 change inputs, commit, inspect results and retry. These positions are deliberately
 separate examples rather than a complete game or an authoritative live room.
 
@@ -40,6 +40,36 @@ that a prior passer can bid again. Direct PDF retrieval returned 403, so no new
 binary/visual source inspection is claimed. Links remain developer provenance;
 the player lesson links only to internal rules.
 
+The Nexus position uses four base factions and two or one Emperor strongholds.
+Players accept an incoming offer, make an offer to a fixed accepting/waiting
+partner, stay unallied, withdraw an unanswered offer or break a formed alliance.
+Closing the Nexus locks these decisions. A separate explicit teaching step
+checks the unchanged board at a later Mentat Pause; it does not simulate the
+intervening phases or award a victory at the moment of alliance formation.
+Three shared strongholds fall short; four qualify for both allies.
+
+`quoteNexusAlliance` extracts existing ordinary offer/pairing behavior into a
+shared pure quote. The live engine retains phase authorization, Homeworld
+restrictions, alliance dates, Nexus Card forfeiture, readiness and history.
+`strongholdProgress` and `quoteVictory` supply the teaching result. Physical
+forces stay with their original owner. The response scripts are local teaching
+scenarios, not changes to live AI. Funding, alliance powers, movement restrictions,
+special victory and expansion exceptions are not simulated in this example.
+The base rulebook's Alliances (Nexus) and Mentat Pause sections remain the rule
+authority; fresh publisher-indexed rulebook/quick-start results confirm the
+ordinary two-member/four-stronghold contract. No new ambiguous ruling is inferred.
+
+The version 4 save whitelists alliance choices and validates the bounded
+opening/offer/withdraw/break sequence and phase order. Prior lesson identities,
+auction history and every other accepted practice choice remain intact.
+`tests/introduction-alliance.test.ts` compares all 24 offered scenario/holding/
+action combinations with actual engine alliance transitions, checks later victory,
+JSON continuation, closed-Nexus rejection and every version 3 lesson migration.
+`tests/nexus-alliance.test.ts` checks pure immutability and live-engine integration;
+existing Nexus Card forfeiture tests cover the retained expansion side effects.
+Final independent review, browser, source-bound checks and saved-game preservation
+are recorded in the private checkpoint and Git message.
+
 The movement position starts with five ordinary forces in Red Chasm. It compares
 range one with range three from a separate Arrakeen occupant, exact sectors,
 storm exclusion and a stronghold already occupied by two other factions. Accepted
@@ -51,10 +81,10 @@ actual authoritative `applyAction` transitions; no live movement rule changed.
 The existing wheel, keyboard controls and card inspectors remain available.
 Lesson changes focus the heading; responsive columns stack on small screens.
 Browser storage contains only a versioned, validated set of lesson choices under
-`dune-introduction-v1`. Version 3 payloads explicitly migrate all five version 1
-and seven version 2 lesson positions to the same lesson after insertion,
-preserving prior choices and committed outcomes. New bidding fields start at
-their defaults; version 1 also receives movement/Traitor defaults. Hot updates
+`dune-introduction-v1`. Version 4 payloads explicitly migrate all five version 1,
+seven version 2 and eight version 3 lesson positions to the same lesson after insertion,
+preserving prior choices and committed outcomes. New alliance fields start at their defaults for every older version.
+Versions 1 and 2 receive bidding defaults; version 1 also receives movement/Traitor defaults. Hot updates
 remount the lesson state to apply this migration. Only the player's bid/pass
 history is saved; deterministic replay validates the complete auction and rejects
 underbids, overspending, full-hand actions and actions after the auction ends.
@@ -87,7 +117,7 @@ re-entry, finite termination and integer/funding limits. Final source-bound
 browser/check/build and preservation evidence for bidding belongs to its private
 checkpoint and Git message.
 
-This does not replace a full interactive curriculum. Alliances, broader movement/arrival powers, faction lessons, Advanced
+This does not replace a full interactive curriculum. Alliance powers, broader movement/arrival powers, faction lessons, Advanced
 support and expansion lessons remain future work. The expanded lessons retain
 Partial/Prototyped coverage. Final browser/check/build, preservation and Git
 evidence for this follow-up belong to its source-bound private checkpoint. No rules mode, expansion or publication gate is opened.