Add Basic group alliance preview to lobby

docs/OPTIONAL_ALLIANCE_VICTORY.md

@@ -1,5 +1,31 @@
 # Optional three-stronghold alliance victory
 
+## Basic classic group lobby preview — 29 October 2026
+
+**Prototyped / Partial.** A host may explicitly select a group-alliance
+development preview in a fresh Basic game with three or more classic faction
+seats. The available variants are a maximum of three members with four
+strongholds, a maximum of three with three strongholds, or any number of
+members with three strongholds. Changing the setting clears human readiness.
+The separate short-alliance option, two-controller setup, Advanced, expansions
+and other optional modules are excluded from this initial lobby entry.
+
+Start creates the empty group ledger through the ordinary setup path; it does
+not modify existing games. Existing pair offers, unanimous group admission and
+leave, the staged faction benefits and minimal bot paths then apply. The game
+and lobby warn that group timing, benefits and other interactions remain
+unfinished. This preview does not certify complete group rules or open normal
+mode/publication gates; historical statements below that no lobby could create
+a ledger describe earlier checkpoints.
+
+The [focused journey](../tests/coalition-preview-lobby.test.ts) uses genuine
+public start, setup and first-turn actions; only the unopened Spice deck order
+is chosen to reach the next Nexus. Pair formation, group consent and bot
+proposals use native actions; the resulting alliance continues through the
+following turn to the next Storm. It also covers settings, readiness and invalid
+starts. Full group games, later interactions, expansion and Advanced entry,
+and deployed acceptance remain open.
+
 ## Group Fremen–Guild shipment answer — 29 October 2026
 
 **Prototyped / Partial.** In the staged Basic group, a Fremen member can