feat: Add Double Battles

.gitignore

@@ -2,6 +2,9 @@
 cache/
 out/
 
+# Default forge gas snapshot (we use snapshots/ directory instead)
+.gas-snapshot
+
 # Ignores development broadcast logs
 !/broadcast
 /broadcast/*/31337/

CHANGELOG.md

@@ -0,0 +1,180 @@
+# Changelog
+
+## Double Battles Implementation
+
+This document summarizes all changes made to implement double battles support.
+
+---
+
+### Core Data Structure Changes
+
+#### `src/Enums.sol`
+- Added `GameMode` enum: `Singles`, `Doubles`
+
+#### `src/Structs.sol`
+- **`BattleArgs`** and **`Battle`**: Added `GameMode gameMode` field
+- **`BattleData`**: Added `slotSwitchFlagsAndGameMode` (packed field: lower 4 bits = per-slot switch flags, bit 4 = game mode)
+- **`BattleContext`** / **`BattleConfigView`**: Added `p0ActiveMonIndex0`, `p0ActiveMonIndex1`, `p1ActiveMonIndex0`, `p1ActiveMonIndex1`, `slotSwitchFlags`, `gameMode`
+
+#### `src/Constants.sol`
+- Added `GAME_MODE_BIT`, `SWITCH_FLAGS_MASK`, `ACTIVE_MON_INDEX_MASK` for packed storage
+
+---
+
+### New Files
+
+#### `src/BaseCommitManager.sol`
+Extracted shared commit/reveal logic from singles and doubles managers:
+- Common errors, events, and storage
+- Shared validation functions: `_validateCommit`, `_validateRevealPreconditions`, `_validateRevealTiming`, `_updateAfterReveal`, `_shouldAutoExecute`
+
+#### `src/DoublesCommitManager.sol`
+Commit/reveal manager for doubles handling 2 moves per player per turn:
+- `commitMoves(battleKey, moveHash)` - Single hash for both moves
+- `revealMoves(...)` - Reveal both slot moves with cross-slot switch validation
+
+---
+
+### Interface Changes
+
+#### `src/IEngine.sol`
+```solidity
+function getActiveMonIndexForSlot(bytes32 battleKey, uint256 playerIndex, uint256 slotIndex) external view returns (uint256);
+function getGameMode(bytes32 battleKey) external view returns (GameMode);
+function switchActiveMonForSlot(uint256 playerIndex, uint256 slotIndex, uint256 monToSwitchIndex) external;
+function setMoveForSlot(bytes32 battleKey, uint256 playerIndex, uint256 slotIndex, uint256 moveIndex, bytes32 salt, uint240 extraData) external;
+```
+
+#### `src/IValidator.sol`
+```solidity
+function validatePlayerMoveForSlot(bytes32 battleKey, uint256 moveIndex, uint256 playerIndex, uint256 slotIndex, uint240 extraData) external returns (bool);
+function validatePlayerMoveForSlotWithClaimed(bytes32 battleKey, uint256 moveIndex, uint256 playerIndex, uint256 slotIndex, uint240 extraData, uint256 claimedByOtherSlot) external returns (bool);
+function validateSpecificMoveSelection(bytes32 battleKey, uint256 moveIndex, uint256 playerIndex, uint256 slotIndex, uint240 extraData) external returns (bool);
+```
+
+---
+
+### Engine Changes
+
+#### Unified Active Mon Index Packing
+- Singles and doubles now use the same 4-bit-per-slot packing format
+- Singles uses slot 0 only; doubles uses slots 0 and 1
+- Removed deprecated `_packActiveMonIndices`, `_unpackActiveMonIndex`, `_setActiveMonIndex`
+- All code now uses `_unpackActiveMonIndexForSlot` and `_setActiveMonIndexForSlot`
+
+#### Slot-Aware Effect Execution
+- Added overloaded `_runEffects` accepting explicit `monIndex` parameter
+- Switch effects (`OnMonSwitchIn`, `OnMonSwitchOut`) pass the switching mon's index
+- `dealDamage` passes target mon index to `AfterDamage` effects
+- `updateMonState` passes affected mon index to `OnUpdateMonState` effects
+
+#### Slot-Aware Damage Calculations
+- `getDamageCalcContext` now accepts `attackerSlotIndex` and `defenderSlotIndex` parameters
+- `AttackCalculator._calculateDamage` and `_calculateDamageView` updated with slot parameters
+- Ensures doubles damage calculations use correct attacker/defender stats based on slot
+- All mon-specific attacks updated to pass explicit slot indices (singles use 0, 0)
+
+#### Doubles Execution Flow
+- `_executeDoubles` handles 4 moves per turn with priority/speed ordering
+- `_checkForGameOverOrKO_Doubles` checks both slots for each player
+- Per-slot switch flags track which slots need to switch after KOs
+
+---
+
+### Validator Changes
+
+#### `src/DefaultValidator.sol`
+- `validateSwitch` checks both slots in doubles mode
+- `validateSpecificMoveSelection` accepts `slotIndex` for correct mon lookup
+- `_getActiveMonIndexFromContext` helper for slot-aware active mon retrieval
+- Unified `_hasValidSwitchTargetForSlot` with optional `claimedByOtherSlot` parameter
+
+---
+
+### Test Coverage
+
+#### `test/DoublesValidationTest.sol` (36 tests)
+- Turn 0 switch requirements
+- KO'd slot handling (with/without valid switch targets)
+- Both slots KO'd scenarios (0, 1, or 2 reserves)
+- Single-player switch turns (one player switches, other attacks)
+- Force-switch moves targeting specific slots
+- Storage reuse between singles↔doubles transitions
+- Effects running on correct mon for both slots
+- Move validation using correct slot's mon stamina
+- AfterDamage effects healing correct mon
+- Slot 1 damage calculations (defender stats, attacker stats)
+
+#### `test/DoublesCommitManagerTest.sol` (11 tests)
+- Commit/reveal flow for doubles
+- Move execution ordering by priority and speed
+- Position tiebreaker for equal speed
+- Game over detection when all mons KO'd
+
+#### Test Mocks Added
+- `DoublesTargetedAttack` - Attack targeting specific opponent slot
+- `DoublesForceSwitchMove` - Force-switch specific opponent slot
+- `DoublesEffectAttack` - Apply effect to specific slot
+- `EffectApplyingAttack` - Generic effect applicator for testing
+- `MonIndexTrackingEffect` - Tracks which mon effects run on
+- `DoublesSlotAttack` - Attack using AttackCalculator with explicit slot parameters
+
+---
+
+### Client Usage
+
+#### Starting a Doubles Battle
+```solidity
+Battle memory battle = Battle({
+    // ... other fields ...
+    moveManager: address(doublesCommitManager),
+    gameMode: GameMode.Doubles
+});
+```
+
+#### Turn Flow
+```solidity
+// Commit hash of both moves
+bytes32 moveHash = keccak256(abi.encodePacked(
+    moveIndex0, extraData0,
+    moveIndex1, extraData1,
+    salt
+));
+doublesCommitManager.commitMoves(battleKey, moveHash);
+
+// Reveal both moves
+doublesCommitManager.revealMoves(battleKey, moveIndex0, extraData0, moveIndex1, extraData1, salt, true);
+```
+
+#### KO'd Slot Handling
+- KO'd slot with valid switch targets → must SWITCH
+- KO'd slot with no valid switch targets → must NO_OP
+- Both slots KO'd with one reserve → slot 0 switches, slot 1 NO_OPs
+
+---
+
+### Future Work
+
+#### Target Redirection
+When a target slot is KO'd mid-turn, moves targeting that slot should redirect or fail. Currently handled by individual move implementations.
+
+#### Move Targeting System
+- Standardize targeting semantics (self, ally, opponent slot 0/1, both opponents, all)
+- Consider `TargetType` enum and standardized `extraData` encoding
+
+#### Speed Tie Handling
+Currently uses basic speed comparison with position tiebreaker. May need explicit rules (random, player advantage).
+
+#### Ability/Effect Integration
+- Abilities affecting both slots (e.g., Intimidate)
+- Weather/terrain affecting 4 mons
+- Spread moves hitting multiple targets
+
+#### Execution Pattern Unification
+- Singles: `revealMove` → `execute` directly
+- Doubles: `revealMoves` → `setMoveForSlot` × 2 → `execute`
+- Consider unifying if performance permits
+
+#### Slot Information in Move Interface
+- `IMoveSet.move()` doesn't receive attacker's slot index
+- Limits slot-aware move logic in doubles

snapshots/EngineGasTest.json

@@ -1,17 +1,17 @@
 {
-  "B1_Execute": "973562",
-  "B1_Setup": "812723",
-  "B2_Execute": "753779",
-  "B2_Setup": "278155",
-  "Battle1_Execute": "494044",
-  "Battle1_Setup": "789140",
-  "Battle2_Execute": "408734",
-  "Battle2_Setup": "234804",
-  "FirstBattle": "3493668",
-  "Intermediary stuff": "44162",
-  "SecondBattle": "3586835",
-  "Setup 1": "1668829",
-  "Setup 2": "295644",
-  "Setup 3": "335644",
-  "ThirdBattle": "2904295"
+  "B1_Execute": "1020627",
+  "B1_Setup": "817509",
+  "B2_Execute": "795025",
+  "B2_Setup": "282847",
+  "Battle1_Execute": "512654",
+  "Battle1_Setup": "793925",
+  "Battle2_Execute": "427344",
+  "Battle2_Setup": "237589",
+  "FirstBattle": "3647997",
+  "Intermediary stuff": "43924",
+  "SecondBattle": "3765806",
+  "Setup 1": "1673640",
+  "Setup 2": "298473",
+  "Setup 3": "338195",
+  "ThirdBattle": "3058698"
 }

snapshots/MatchmakerTest.json

@@ -1,5 +1,5 @@
 {
-  "Accept1": "305380",
-  "Accept2": "33991",
-  "Propose1": "197148"
+  "Accept1": "307493",
+  "Accept2": "34420",
+  "Propose1": "199579"
 }