fix: CheckWeaponAvail — double deref weapon table, fix condition logic

Two bugs in the agent-generated port:
1. DDGame+0x510 is a POINTER to the weapon table (needs double deref),
not an inline offset. Was reading from wrong memory.
2. Condition was inverted: (777C==0 || entry!=0) → main path with
super weapon checks. The else branch (777C!=0 && entry==0) returns
-2 or 0. Original code had these swapped.

All 7 usercall InitGameState sub-functions now ported and passing:
- SpriteGfxTable__Init, RingBuffer__Init (Group A)
- InitTeamScoring, InitAllianceData (Group B)
- InitTurnState, IsSuperWeapon, InitLandscapeFlags, CheckWeaponAvail (Group C)

Headful + headless replay tests PASS.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

crates/openwa-core/src/engine/game_state_init.rs

@@ -383,35 +383,36 @@ pub unsafe fn check_weapon_avail(ddgame: *mut u8, weapon_index: u32) -> i32 {
         _ => {}
     }
 
-    // Step 2: Check weapon table entry
-    // weapon_table_entry is at ddgame+0x510 + 0x10 + weapon_index*0x1D0
-    let weapon_table_entry =
-        *(ddgame.add(0x510 + 0x10 + (weapon_index as usize) * 0x1D0) as *const u8);
-
-    if *(ddgame.add(0x777C) as *const u32) == 0 && weapon_table_entry == 0 {
-        if game_version > 0x29 && *(game_info.add(0xD959) as *const u8) != 0 {
-            return -2;
+    // Step 2: Branch on weapon table entry + DDGame+0x777C
+    // DDGame+0x510 is a POINTER to the weapon table (double deref)
+    let weapon_table = *(ddgame.add(0x510) as *const *const u8);
+    let weapon_entry = *(weapon_table.add(0x10 + (weapon_index as usize) * 0x1D0) as *const i32);
+
+    if *(ddgame.add(0x777C) as *const i32) == 0 || weapon_entry != 0 {
+        // Main path: check super weapon, 7E25, etc.
+        let super_result = is_super_weapon(weapon_index, *(ddgame.add(0x7E3F) as *const u8));
+        // After is_super_weapon, re-read ddgame (ECX may change in original — doesn't matter in Rust)
+        if super_result != 0 && *(game_info.add(0xD93C) as *const u8) == 0 {
+            // (game_version < 0x2A) - 1: if < 0x2A → 1-1=0, else → 0-1=-1
+            return (game_version < 0x2A) as i32 - 1;
         }
-        return 0;
-    }
 
-    // Step 3: Super weapon check
-    let super_result = is_super_weapon(weapon_index, *(ddgame.add(0x7E3F) as *const u8));
-    if super_result != 0 && *(game_info.add(0xD93C) as *const u8) == 0 {
-        // (game_version < 0x2A) - 1: if version < 0x2A → 0, else → -1
-        return if game_version < 0x2A { 0 } else { -1 };
-    }
+        if *(ddgame.add(0x7E25) as *const u8) == 0 {
+            return 1;
+        }
 
-    // Step 4: Check DDGame+0x7E25 and weapon_index condition
-    if *(ddgame.add(0x7E25) as *const u8) == 0 {
-        return 1;
+        // Check if weapon_index == (0x19 - (game_info+0xD956 != 0))
+        let d956_nonzero = (*(game_info.add(0xD956) as *const u8) != 0) as u32;
+        if weapon_index != 0x19 - d956_nonzero {
+            return 1;
+        }
+
+        return 0;
     }
 
-    // weapon_index != (0x19 - (game_info+0xD956 != 0))
-    let d956_nonzero = *(game_info.add(0xD956) as *const u8) != 0;
-    let threshold = 0x19u32 - d956_nonzero as u32;
-    if weapon_index != threshold {
-        return 1;
+    // Else branch: 777C != 0 AND weapon_entry == 0
+    if game_version > 0x29 && *(game_info.add(0xD959) as *const u8) != 0 {
+        return -2;
     }
 
     0

crates/openwa-wormkit/src/replacements/ddgame_init.rs

@@ -235,8 +235,11 @@ pub fn install() -> Result<(), String> {
             init_turn_state_trampoline as *const (),
         )?;
 
-        // TODO: CheckWeaponAvail has a porting bug — disabled until fixed
-        // hook::install("DDGame__CheckWeaponAvail", va::CHECK_WEAPON_AVAIL, check_weapon_avail_trampoline as *const ())?;
+        hook::install(
+            "DDGame__CheckWeaponAvail",
+            va::CHECK_WEAPON_AVAIL,
+            check_weapon_avail_trampoline as *const (),
+        )?;
 
         hook::install(
             "CGameTask__InitLandscapeFlags",