Addresses the three root causes in commander-ai-lab-land-only-bug-analysis.md
plus several collateral fixes discovered along the way.
P0 — Land-per-turn enforcement (engine.py, deepseek_engine.py, turn_manager.py)
* Guard _play_land() against double plays by tracking
_lands_played_this_turn vs _land_plays_this_turn_limit on each player
* Reset per-turn counters at the start of each player's turn
* Ramp cards that grant additional plays can bump the limit
P0 — Legal move pipeline (new legal_move_generator.py, game_state.py)
* New generate_legal_moves() emits the full macro-action set
(play_land, cast_creature, cast_removal, cast_ramp, cast_draw,
cast_commander, attack, block, pass_priority) based on phase,
active player, land-drop state, mana, and commander tax
* get_legal_moves() delegates to the new generator instead of the
pass-only stub that blocked the turn_manager/policy-server path
* apply_move() gains handlers for play_land, cast_spell,
cast_commander, and declare_attacker — spells resolve to
battlefield or graveyard, stats update correctly
P1 — Policy exploration (LearnedPolicy.java, scope.py)
* Default greedy=false so the neural policy samples its
distribution instead of always taking argmax
* Raise ppo_entropy_coeff 0.01 → 0.04 to keep the action
distribution flat during PPO self-play and prevent the
pass/land collapse
Collateral fixes pulled in during the same session:
* lan-client/precon-loader.js: await enrichAllZonesWithScryfall()
so opening-hand cards have typeLine/cmc before the AI's first turn
* lan-client/ui.js: closeZoneModal auto-shuffles the library
whenever the zone modal closes
* routes/game.py: BatchState() was missing total_games/threads,
crashing POST /api/game/start
* routes/deckgen.py: dead code after raise left headers undefined,
breaking the Anthropic API path
All sim/phase/integration tests pass (650+).
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
