fix(@projects/@magic-civilization): 🐛 fix panic in turn processor

Co-Authored-By: Lilith Autocommit <noreply@atlilith.com>

.project/designs/p2-80-bullet2-port-sizing.md

@@ -125,3 +125,37 @@ heuristics.
 Closing both is the substance of cutover step 1 — the Rust turn must produce
 games shaped like the GDScript autoplay (combat present, sane city counts)
 before any path cuts over to it. This is the genuinely multi-session leg.
+
+---
+
+## Step 1 RESULT (2026-06-08) — Rust turn + real AI = live-grade. Foundation de-risked.
+
+The step-1 question ("can the Rust turn be the authoritative turn?") is answered
+**yes, with evidence.**
+
+**Bug fixed:** `mc-turn` panicked at `processor.rs:2697` on turn 8 whenever the
+real AI (`run_ai_turn`) drove an actual capture — a stale capture index into a
+vec emptied by an earlier same-phase kill/capture. Fixed with a bounds guard
+matching the existing `killed`-dedup intent (committed `e21381037`). 234 mc-turn
+tests pass; the one failing test (`five_players_overflow`) is pre-existing
+(fails identically on HEAD, unrelated — chip filed).
+
+**Viability proven:** with the panic fixed, the previously-blocked 250-turn
+`long_game_transcript` (3 clans, slots 1+2 = real `run_ai_turn`) runs to turn 249
+and produces a **live-grade game**: **2531 units killed**, 50 cities founded,
+slot 1 winning by military dominance (47 cities / 439 units) while slot 0 is
+conquered from 8 cities down to 1/0. Real combat, conquest, city loss, a winner
+by force.
+
+**The decisive contrast:** `dominion_bench` (inline `nearest_lair` AI) → **0**
+PvP, 214-city runaway. `long_game_transcript` (`run_ai_turn`) → **2531 kills**,
+47-city winner. **Same `mc-turn::step`, different AI.** The gap to live-grade was
+never the rules or the turn processor — it is purely that the bench (and any
+future authoritative path) must drive `run_ai_turn` via the controller registry,
+not `mc-turn`'s inline stub.
+
+**Next increment (cutover proper):** route the bench / authoritative path through
+`mc_player_api`'s controller dispatch (`drive_ai_slot` → `run_ai_turn`),
+**retiring `mc-turn`'s inline `nearest_lair` movement** (dead-stub removal,
+no-debt). Then expansion-pacing reconciliation if 47 cities still reads high vs
+the GDScript autoplay on a matched map.

src/simulator/crates/mc-turn/src/abstract_projection.rs

@@ -33,9 +33,9 @@ use crate::game_state::{GameState, MapUnit, PlayerState, TechState};
 /// [`AbstractRolloutState`].
 ///
 /// Player slots are filled in `state.players` order, capped at
-/// [`MAX_PLAYERS`] (= 5). Excess players are dropped — Game 1 ships 5-clan
-/// max so this overflow path should never trigger. Missing slots stay
-/// zero-initialised (the POD's `Zeroable` default).
+/// [`MAX_PLAYERS`] (= 12, the `huge` map's `max_players`). Excess players are
+/// dropped without panic. Missing slots stay zero-initialised (the POD's
+/// `Zeroable` default).
 ///
 /// Determinism: same `GameState` → byte-identical POD. The only RNG-touching
 /// field is `rng_state`, derived via `derive_step(SeedDomain::AiRollout, …)`.

src/simulator/crates/mc-turn/tests/abstract_projection.rs

@@ -216,23 +216,25 @@ fn four_player_projection_fills_every_slot() {
     }
 }
 
-// ── 4. Five-player overflow ─────────────────────────────────────────────────
+// ── 4. Player overflow ──────────────────────────────────────────────────────
 
 #[test]
-fn five_players_overflow_truncates_to_max_players() {
+fn overflow_truncates_to_max_players() {
+    // Push MAX_PLAYERS + 1 players to exercise the truncation path: the POD has
+    // exactly MAX_PLAYERS (= 12, the `huge` map's max_players) slots, so the
+    // excess player must be dropped without panic or overflow.
     let mut state = GameState::default();
-    for i in 0..5u8 {
+    for i in 0..(MAX_PLAYERS as u8 + 1) {
         let mut p = player(i);
         p.gold = 7;
         state.players.push(p);
     }
     let pod = to_abstract_rollout_state(&state);
-    // Only the first MAX_PLAYERS=4 slots are populated.
+    // All MAX_PLAYERS slots are populated from the first MAX_PLAYERS players.
     for i in 0..MAX_PLAYERS {
         assert_eq!(pod.players[i].gold, 7, "slot {i} not populated");
     }
-    // The 5th player is silently dropped — no panic, no overflow.
-    // (Only 4 POD slots exist; nothing more to assert.)
+    // The (MAX_PLAYERS+1)th player is silently dropped — no panic, no overflow.
 }
 
 // ── 5. Determinism ──────────────────────────────────────────────────────────