Drive battle rounds through cutscene items, fix render/init bugs

Adds BATTLE_START, BATTLE_SET_STATE and BATTLE_WAIT_SELECTION cutscene
items so a battle's state transitions (opening -> pre-round -> selection
-> executing) are chained through the running cutscene, with
cutsceneSystemInsertItemsNext/InsertItems splitting "splice" from
"splice and advance immediately". Adds battlestateselection's
get-current-fighter/player-attack/player-flee API backing the battle UI,
and battleMoveGetIdByName for JSON-authored ability lookups.

Fixes: off-by-one in battleMoveInit that let the first-defined move
alias BATTLE_MOVE_ID_NULL; a segfault in scenebattle.c from rendering
unfilled (NULL) fighter slots; stale battleGetCurrentFighter/
battlePlayerAttack/battlePlayerFlee references in the battle UI.

Adds assertions across the battle/scene/UI code for fighter-index
bounds and non-null invariants. Updates battletest.jsonc for the new
BATTLE_START item schema.

Co-Authored-By: Claude Sonnet 5 <[email protected]>

assets/cutscenes/battletest.jsonc

@@ -1,24 +1,22 @@
 {
   "items": [
     {
-      "type": "START_BATTLE",
-      "encounterType": "REGULAR",
-      "fleeAvailable": true,
+      "type": "BATTLE_START",
       "enemies": [
         {
-          "stats": { "attack": 8, "defense": 4, "magic": 0, "speed": 5, "luck": 2 },
-          "healthMax": 30,
-          "mpMax": 0
+          "stats": {
+            "attack": 8, "defense": 4, "magic": 0, "speed": 5, "luck": 2,
+            "healthMax": 30, "mpMax": 0
+          },
+          "abilities": ["fire"]
         },
         {
-          "stats": { "attack": 6, "defense": 3, "magic": 0, "speed": 7, "luck": 2 },
-          "healthMax": 20,
-          "mpMax": 0
+          "stats": {
+            "attack": 6, "defense": 3, "magic": 0, "speed": 7, "luck": 2,
+            "healthMax": 20, "mpMax": 0
+          }
         }
       ]
-    },
-    {
-      "type": "REGULAR_BATTLE"
     }
   ]
 }

src/dusk/rpg/battle/battle.c

@@ -9,6 +9,7 @@
 #include "assert/assert.h"
 #include "util/memory.h"
 #include "rpg/cutscene/cutscenesystem.h"
+#include "scene/scene.h"
 
 battle_t BATTLE;
 
@@ -22,7 +23,8 @@ void battleStart(
   assertNotNull(fighters, "Fighters cannot be NULL");
 
   #if DUSK_ASSERTIONS
-    // Must be at least two non null fighter present.
+    // Must be at least two non null fighter present, may need to ensure they
+    // are from seperate teams also.
     uint8_t nonNullCount = 0;
     for(uint8_t i = 0; i < BATTLE_FIGHTER_POS_COUNT; i++) {
       if(fighters[i] != NULL) nonNullCount++;
@@ -39,18 +41,38 @@ void battleStart(
     sizeof(battlefighter_t *) * BATTLE_FIGHTER_POS_COUNT
   );
 
-  // Call init on opening state.
-  BATTLE.state = BATTLE_STATE_OPENING;
+  // Enter the opening state.
+  battleSetState(BATTLE_STATE_OPENING);
+
+  // Change scene
+  sceneSet(SCENE_TYPE_BATTLE);
+}
+
+void battleSetState(const battlestate_t next) {
+  assertTrue(next < BATTLE_STATE_COUNT, "Invalid battle state");
+  assertNotNull(BATTLE_STATE_FUNCTIONS[next].init, "Missing state init function");
+  assertNotNull(BATTLE_STATE_FUNCTIONS[next].update, "Missing state update function");
+  assertNotNull(BATTLE_STATE_FUNCTIONS[next].dispose, "Missing state dispose function");
+
+  if(BATTLE.state != BATTLE_STATE_NULL) {
+    BATTLE_STATE_FUNCTIONS[BATTLE.state].dispose();
+  }
+  BATTLE.state = next;
   BATTLE_STATE_FUNCTIONS[BATTLE.state].init();
 }
 
 void battleUpdate(void) {
   if(BATTLE.state == BATTLE_STATE_NULL) return;
+  assertTrue(BATTLE.state < BATTLE_STATE_COUNT, "Invalid battle state");
+  assertNotNull(BATTLE_STATE_FUNCTIONS[BATTLE.state].update, "Missing state update function");
+
   BATTLE_STATE_FUNCTIONS[BATTLE.state].update();
 }
 
 void battleDispose(void) {
   if(BATTLE.state == BATTLE_STATE_NULL) return;
+  assertTrue(BATTLE.state < BATTLE_STATE_COUNT, "Invalid battle state");
+  assertNotNull(BATTLE_STATE_FUNCTIONS[BATTLE.state].dispose, "Missing state dispose function");
 
   BATTLE_STATE_FUNCTIONS[BATTLE.state].dispose();
   memoryZero(&BATTLE, sizeof(battle_t));

src/dusk/rpg/battle/battle.h

@@ -49,6 +49,14 @@ void battleStart(
   battlefighter_t *fighters[BATTLE_FIGHTER_POS_COUNT]
 );
 
+/**
+ * Transitions the battle to a new state: disposes the current state (if
+ * any) and initializes next.
+ *
+ * @param next The state to transition to.
+ */
+void battleSetState(const battlestate_t next);
+
 /**
  * Updates the battle system.
  */

src/dusk/rpg/battle/move/battlemove.c

@@ -8,6 +8,7 @@
 #include "battlemove.h"
 #include "asset/asset.h"
 #include "asset/loader/assetloader.h"
+#include "assert/assert.h"
 #include "util/memory.h"
 #include "util/string.h"
 #include <string.h>
@@ -17,7 +18,7 @@ uint8_t BATTLE_MOVE_COUNT;
 
 errorret_t battleMoveInit(void) {
   memoryZero(BATTLE_MOVES, sizeof(BATTLE_MOVES));
-  BATTLE_MOVE_COUNT = BATTLE_MOVE_ID_NULL;
+  BATTLE_MOVE_COUNT = BATTLE_MOVE_ID_NULL + 1;// Reserve NULL.
 
   // Get moves JSON.
   assetentry_t *entry = assetLock(
@@ -126,3 +127,13 @@ errorret_t battleMoveInit(void) {
   assetUnlockEntry(entry);
   errorOk();
 }
+
+battlemoveid_t battleMoveGetIdByName(const char_t *name) {
+  assertNotNull(name, "name must not be NULL");
+
+  for(battlemoveid_t id = BATTLE_MOVE_ID_NULL + 1; id < BATTLE_MOVE_COUNT; id++) {
+    if(stringEquals(BATTLE_MOVES[id].name, name)) return id;
+  }
+
+  return BATTLE_MOVE_ID_NULL;
+}

src/dusk/rpg/battle/move/battlemove.h

@@ -32,3 +32,11 @@ extern battleability_t BATTLE_MOVES[BATTLE_MOVE_COUNT_MAX];
  * @return Any error that occurs.
  */
 errorret_t battleMoveInit(void);
+
+/**
+ * Finds a move's id by name (exact match).
+ *
+ * @param name The move name to search for.
+ * @return The matching move's id, or BATTLE_MOVE_ID_NULL if not found.
+ */
+battlemoveid_t battleMoveGetIdByName(const char_t *name);

src/dusk/rpg/battle/state/battlestateopening.c

@@ -6,9 +6,17 @@
  */
 
 #include "battlestateopening.h"
+#include "rpg/cutscene/item/cutsceneitem.h"
+#include "rpg/cutscene/cutscenesystem.h"
 
 void battleStateOpeningInit(void) {
-
+  const cutsceneitem_t items[] = {
+    {
+      .type = CUTSCENE_ITEM_TYPE_BATTLE_SET_STATE,
+      .battleSetState = { .state = BATTLE_STATE_PRE_ROUND }
+    }
+  };
+  cutsceneSystemInsertItemsNext(items, sizeof(items) / sizeof(cutsceneitem_t));
 }
 
 void battleStateOpeningUpdate(void) {

src/dusk/rpg/battle/state/battlestatepreround.c

@@ -6,9 +6,20 @@
  */
 
 #include "battlestatepreround.h"
+#include "rpg/cutscene/item/cutsceneitem.h"
+#include "rpg/cutscene/cutscenesystem.h"
 
 void battleStatePreRoundInit(void) {
-
+  const cutsceneitem_t items[] = {
+    {
+      .type = CUTSCENE_ITEM_TYPE_BATTLE_SET_STATE,
+      .battleSetState = { .state = BATTLE_STATE_SELECTION }
+    },
+    {
+      .type = CUTSCENE_ITEM_TYPE_BATTLE_WAIT_SELECTION
+    }
+  };
+  cutsceneSystemInsertItemsNext(items, sizeof(items) / sizeof(cutsceneitem_t));
 }
 
 void battleStatePreRoundUpdate(void) {

src/dusk/rpg/battle/state/battlestateselection.c

@@ -6,15 +6,114 @@
  */
 
 #include "battlestateselection.h"
+#include "rpg/battle/battle.h"
+#include "rpg/cutscene/item/cutsceneitem.h"
+#include "rpg/cutscene/cutscenesystem.h"
+#include "assert/assert.h"
+
+// TEMPORARY: hardcoded pending a real moves.jsonc-backed registry lookup.
+#define BATTLE_MOVE_ID_ATTACK ((battlemoveid_t)1)
 
 void battleStateSelectionInit(void) {
-
+  BATTLE.stateData.selection.selectionIndex = 0;
 }
 
 void battleStateSelectionUpdate(void) {
+  battlestateselection_t *state = &BATTLE.stateData.selection;
 
+  while(state->selectionIndex < BATTLE_FIGHTER_POS_COUNT) {
+    const uint8_t fighterIndex = state->selectionIndex;
+    if(!battleStateSelectionFighterNeedsDecision(fighterIndex)) {
+      state->selectionIndex++;
+      continue;
+    }
+
+    battlefighter_t *fighter = BATTLE.fighters[fighterIndex];
+    if(fighter->controller != BATTLE_FIGHTER_CONTROLLER_AI) {
+      // Player-controlled: wait for battleStateSelectionPlayerAttack/Flee.
+      return;
+    }
+
+    const battlefighterteam_t enemyTeam =
+      fighter->team == BATTLE_FIGHTER_TEAM_ALLY ?
+        BATTLE_FIGHTER_TEAM_ENEMY : BATTLE_FIGHTER_TEAM_ALLY;
+
+    uint8_t targetIndex = 0xFF;
+    for(uint8_t i = 0; i < BATTLE_FIGHTER_POS_COUNT; i++) {
+      battlefighter_t *candidate = BATTLE.fighters[i];
+      if(candidate == NULL) continue;
+      if(candidate->team != enemyTeam) continue;
+      if(!battleFighterIsAlive(candidate)) continue;
+      targetIndex = i;
+      break;
+    }
+
+    if(targetIndex != 0xFF) {
+      battleStateSelectionQueueAttack(fighterIndex, targetIndex);
+    }
+    state->selectionIndex++;
+  }
+
+  const cutsceneitem_t items[] = {
+    {
+      .type = CUTSCENE_ITEM_TYPE_BATTLE_SET_STATE,
+      .battleSetState = { .state = BATTLE_STATE_EXECUTING }
+    }
+  };
+  cutsceneSystemInsertItems(items, sizeof(items) / sizeof(cutsceneitem_t));
 }
 
 void battleStateSelectionDispose(void) {
 
 }
+
+bool_t battleStateSelectionFighterNeedsDecision(const uint8_t fighterIndex) {
+  assertTrue(fighterIndex < BATTLE_FIGHTER_POS_COUNT, "fighterIndex out of bounds");
+
+  battlefighter_t *fighter = BATTLE.fighters[fighterIndex];
+  if(fighter == NULL) return false;
+  if(!battleFighterIsAlive(fighter)) return false;
+
+  return BATTLE.actionsPending[fighterIndex].move == BATTLE_MOVE_ID_NULL;
+}
+
+void battleStateSelectionQueueAttack(
+  const uint8_t fighterIndex,
+  const uint8_t targetIndex
+) {
+  assertTrue(fighterIndex < BATTLE_FIGHTER_POS_COUNT, "fighterIndex out of bounds");
+  assertTrue(targetIndex < BATTLE_FIGHTER_POS_COUNT, "targetIndex out of bounds");
+  assertNotNull(BATTLE.fighters[fighterIndex], "Fighter cannot be NULL");
+  assertNotNull(BATTLE.fighters[targetIndex], "Target cannot be NULL");
+
+  battlemoveaction_t *action = &BATTLE.actionsPending[fighterIndex];
+  action->move = BATTLE_MOVE_ID_ATTACK;
+  action->targets[0] = targetIndex;
+  action->user = BATTLE.fighters[fighterIndex];
+}
+
+battlefighter_t *battleStateSelectionGetCurrentFighter(void) {
+  if(BATTLE.state != BATTLE_STATE_SELECTION) return NULL;
+
+  const uint8_t index = BATTLE.stateData.selection.selectionIndex;
+  if(index >= BATTLE_FIGHTER_POS_COUNT) return NULL;
+
+  return BATTLE.fighters[index];
+}
+
+void battleStateSelectionPlayerAttack(const uint8_t targetIndex) {
+  battlefighter_t *fighter = battleStateSelectionGetCurrentFighter();
+  if(fighter == NULL) return;
+
+  battleStateSelectionQueueAttack(
+    BATTLE.stateData.selection.selectionIndex, targetIndex
+  );
+  BATTLE.stateData.selection.selectionIndex++;
+}
+
+void battleStateSelectionPlayerFlee(void) {
+  battlefighter_t *fighter = battleStateSelectionGetCurrentFighter();
+  if(fighter == NULL) return;
+
+  battleSetState(BATTLE_STATE_FLED);
+}

src/dusk/rpg/battle/state/battlestateselection.h

@@ -6,10 +6,12 @@
  */
 
 #pragma once
-#include "dusk.h"
+#include "rpg/battle/fighter/battlefighter.h"
 
 typedef struct {
-
+  // Cursor into BATTLE.fighters (by position index) for the fighter
+  // currently deciding a move this round.
+  uint8_t selectionIndex;
 } battlestateselection_t;
 
 /**
@@ -18,7 +20,11 @@ typedef struct {
 void battleStateSelectionInit(void);
 
 /**
- * Updates BATTLE_STATE_SELECTION for one frame.
+ * Updates BATTLE_STATE_SELECTION for one frame: auto-decides for every
+ * AI-controlled fighter the cursor passes, stopping once it reaches a
+ * player-controlled fighter awaiting input (see
+ * battleStateSelectionGetCurrentFighter), or transitions to
+ * BATTLE_STATE_EXECUTING once every position has decided.
  */
 void battleStateSelectionUpdate(void);
 
@@ -26,3 +32,49 @@ void battleStateSelectionUpdate(void);
  * Called when the battle leaves BATTLE_STATE_SELECTION.
  */
 void battleStateSelectionDispose(void);
+
+/**
+ * Checks whether the fighter at fighterIndex is a live, undecided
+ * candidate that BATTLE_STATE_SELECTION should still be deciding a move
+ * for.
+ *
+ * @param fighterIndex Index into BATTLE.fighters to check.
+ * @return True if the fighter is alive and has no move queued yet.
+ */
+bool_t battleStateSelectionFighterNeedsDecision(const uint8_t fighterIndex);
+
+/**
+ * Queues a basic attack from fighterIndex against targetIndex.
+ *
+ * @param fighterIndex Index into BATTLE.fighters of the deciding fighter.
+ * @param targetIndex Index into BATTLE.fighters of the target.
+ */
+void battleStateSelectionQueueAttack(
+  const uint8_t fighterIndex,
+  const uint8_t targetIndex
+);
+
+/**
+ * Returns the fighter currently awaiting a decision in
+ * BATTLE_STATE_SELECTION.
+ *
+ * @return Pointer to the fighter awaiting a decision, or NULL if the
+ *         battle isn't in BATTLE_STATE_SELECTION or every position has
+ *         already decided.
+ */
+battlefighter_t *battleStateSelectionGetCurrentFighter(void);
+
+/**
+ * Submits the currently-selecting fighter's attack against a target, if
+ * the battle is in BATTLE_STATE_SELECTION and awaiting a decision. Queues
+ * the move and advances the selection cursor.
+ *
+ * @param targetIndex Index into BATTLE.fighters of the target.
+ */
+void battleStateSelectionPlayerAttack(const uint8_t targetIndex);
+
+/**
+ * Ends the battle immediately with BATTLE_STATE_FLED, if the battle is in
+ * BATTLE_STATE_SELECTION and awaiting a decision.
+ */
+void battleStateSelectionPlayerFlee(void);

src/dusk/rpg/cutscene/cutscenesystem.c

@@ -87,20 +87,34 @@ void cutsceneSystemStartCutsceneAndGoToMarker(
   cutsceneGoTo(marker);
 }
 
-void cutsceneSystemInsertCutscene(const cutscene_t *cutscene) {
-  assertNotNull(cutscene, "Cutscene cannot be NULL");
+void cutsceneSystemInsertItemsNext(
+  const cutsceneitem_t *items,
+  const size_t itemCount
+) {
+  assertNotNull(items, "Items cannot be NULL");
   assertNotNull(
     CUTSCENE_SYSTEM.scene,
-    "cutsceneSystemInsertCutscene called with no cutscene running"
+    "cutsceneSystemInsertItemsNext called with no cutscene running"
   );
 
   cutsceneAppendNext(
-    CUTSCENE_SYSTEM.scene, CUTSCENE_SYSTEM.currentItem,
-    cutscene->items, cutscene->itemCount
+    CUTSCENE_SYSTEM.scene, CUTSCENE_SYSTEM.currentItem, items, itemCount
   );
+}
+
+void cutsceneSystemInsertItems(
+  const cutsceneitem_t *items,
+  const size_t itemCount
+) {
+  cutsceneSystemInsertItemsNext(items, itemCount);
   cutsceneSystemNext();
 }
 
+void cutsceneSystemInsertCutscene(const cutscene_t *cutscene) {
+  assertNotNull(cutscene, "Cutscene cannot be NULL");
+  cutsceneSystemInsertItems(cutscene->items, cutscene->itemCount);
+}
+
 void cutsceneSystemLoad(const char_t *file) {
   assertNotNull(file, "File cannot be NULL");
 

src/dusk/rpg/cutscene/cutscenesystem.h

@@ -109,6 +109,32 @@ void cutsceneSystemStartCutsceneAndGoToMarker(
   const char_t *marker
 );
 
+/**
+ * Splices items into the running cutscene so that items[0] becomes the
+ * very next item, without otherwise disturbing the currently-running
+ * item's progress.
+ *
+ * @param items Items to splice in.
+ * @param itemCount Number of items in items.
+ */
+void cutsceneSystemInsertItemsNext(
+  const cutsceneitem_t *items,
+  const size_t itemCount
+);
+
+/**
+ * Splices items into the running cutscene right after the current item
+ * (see cutsceneSystemInsertItemsNext), then immediately advances into the
+ * first spliced item.
+ *
+ * @param items Items to splice in.
+ * @param itemCount Number of items in items.
+ */
+void cutsceneSystemInsertItems(
+  const cutsceneitem_t *items,
+  const size_t itemCount
+);
+
 /**
  * Splices cutscene's items into the running cutscene.
  *

src/dusk/rpg/cutscene/item/CMakeLists.txt

@@ -16,6 +16,7 @@ add_subdirectory(entity)
 add_subdirectory(item)
 add_subdirectory(maparea)
 add_subdirectory(ui)
+add_subdirectory(battle)
 add_subdirectory(save)
 add_subdirectory(audio)
 add_subdirectory(json)

src/dusk/rpg/cutscene/item/battle/CMakeLists.txt

@@ -0,0 +1,11 @@
+# Copyright (c) 2026 Dominic Masters
+#
+# This software is released under the MIT License.
+# https://opensource.org/licenses/MIT
+
+target_sources(${DUSK_LIBRARY_TARGET_NAME}
+  PUBLIC
+    cutscenebattlestart.c
+    cutscenebattlesetstate.c
+    cutscenebattlewaitselection.c
+)

src/dusk/rpg/cutscene/item/battle/cutscenebattlesetstate.c

@@ -0,0 +1,41 @@
+/**
+ * Copyright (c) 2026 Dominic Masters
+ *
+ * This software is released under the MIT License.
+ * https://opensource.org/licenses/MIT
+ */
+
+#include "rpg/cutscene/item/cutsceneitem.h"
+#include "rpg/battle/battle.h"
+#include "rpg/cutscene/item/json/cutscenejsonbattlestate.h"
+#include "assert/assert.h"
+
+void cutsceneBattleSetStateStart(
+  const cutsceneitem_t *item,
+  cutsceneitemdata_t *data
+) {
+  assertNotNull(item, "item cannot be NULL");
+  battleSetState(item->battleSetState.state);
+}
+
+bool_t cutsceneBattleSetStateUpdate(
+  const cutsceneitem_t *item,
+  cutsceneitemdata_t *data
+) {
+  return true;
+}
+
+errorret_t cutsceneBattleSetStateLoad(
+  yyjson_val *itemObj,
+  cutsceneitem_t *item
+) {
+  battlestate_t state;
+  if(!cutsceneJsonLookupBattleState(
+    yyjson_get_str(yyjson_obj_get(itemObj, "state")), &state
+  )) {
+    errorThrow("Cutscene item (BATTLE_SET_STATE): invalid 'state'");
+  }
+  item->battleSetState.state = state;
+
+  errorOk();
+}

src/dusk/rpg/cutscene/item/battle/cutscenebattlesetstate.h

@@ -0,0 +1,50 @@
+/**
+ * Copyright (c) 2026 Dominic Masters
+ *
+ * This software is released under the MIT License.
+ * https://opensource.org/licenses/MIT
+ */
+
+#pragma once
+#include "rpg/battle/state/battlestate.h"
+#include "rpg/cutscene/item/cutsceneitembase.h"
+
+typedef struct {
+  battlestate_t state;
+} cutscenebattlesetstate_t;
+
+/**
+ * Starts a BATTLE_SET_STATE item, transitioning the battle to the
+ * configured state immediately.
+ *
+ * @param item The cutscene item.
+ * @param data Runtime data storage.
+ */
+void cutsceneBattleSetStateStart(
+  const cutsceneitem_t *item,
+  cutsceneitemdata_t *data
+);
+
+/**
+ * Updates a BATTLE_SET_STATE item (always completes immediately).
+ *
+ * @param item The cutscene item.
+ * @param data Runtime data storage.
+ * @returns true always.
+ */
+bool_t cutsceneBattleSetStateUpdate(
+  const cutsceneitem_t *item,
+  cutsceneitemdata_t *data
+);
+
+/**
+ * Parses a BATTLE_SET_STATE cutscene item's JSON fields into item.
+ *
+ * @param itemObj The item's JSON object.
+ * @param item Destination item, already zeroed by the caller.
+ * @return Error code indicating success or failure of the parse.
+ */
+errorret_t cutsceneBattleSetStateLoad(
+  yyjson_val *itemObj,
+  cutsceneitem_t *item
+);

src/dusk/rpg/cutscene/item/battle/cutscenebattlestart.c

@@ -0,0 +1,144 @@
+/**
+ * Copyright (c) 2026 Dominic Masters
+ *
+ * This software is released under the MIT License.
+ * https://opensource.org/licenses/MIT
+ */
+
+#include "rpg/cutscene/item/cutsceneitem.h"
+#include "rpg/battle/battle.h"
+#include "rpg/battle/party.h"
+#include "assert/assert.h"
+#include "util/memory.h"
+
+battlefighter_t CUTSCENE_BATTLE_START_ENEMY_POOL[
+  CUTSCENE_BATTLE_START_ENEMY_COUNT_MAX
+];
+
+void cutsceneBattleStartStart(
+  const cutsceneitem_t *item,
+  cutsceneitemdata_t *data
+) {
+  assertNotNull(item, "item cannot be NULL");
+
+  const cutscenebattlestart_t *config = &item->battleStart;
+  assertTrue(
+    config->enemyCount <= CUTSCENE_BATTLE_START_ENEMY_COUNT_MAX,
+    "enemyCount out of bounds"
+  );
+
+  battlefighter_t *fighters[BATTLE_FIGHTER_POS_COUNT] = { 0 };
+
+  memoryZero(
+    CUTSCENE_BATTLE_START_ENEMY_POOL,
+    sizeof(CUTSCENE_BATTLE_START_ENEMY_POOL)
+  );
+  for(uint8_t i = 0; i < config->enemyCount; i++) {
+    const cutscenebattlestartenemy_t *enemyConfig = &config->enemies[i];
+    battlefighter_t *enemy = &CUTSCENE_BATTLE_START_ENEMY_POOL[i];
+
+    battleFighterInit(
+      enemy, BATTLE_FIGHTER_TEAM_ENEMY, BATTLE_FIGHTER_CONTROLLER_AI,
+      enemyConfig->stats
+    );
+    for(uint8_t a = 0; a < enemyConfig->abilityCount; a++) {
+      battleFighterAbilityAdd(enemy, enemyConfig->abilities[a]);
+    }
+
+    fighters[i] = enemy;
+  }
+
+  for(uint8_t i = 0; i < PARTY_ACTIVE_SIZE_MAX; i++) {
+    battlefighter_t *member = partyGetOrderMember(i);
+    if(member == NULL) continue;
+
+    fighters[BATTLE_FIGHTER_POS_4 + i] = member;
+  }
+
+  battleStart(fighters);
+}
+
+bool_t cutsceneBattleStartUpdate(
+  const cutsceneitem_t *item,
+  cutsceneitemdata_t *data
+) {
+  return true;
+}
+
+errorret_t cutsceneBattleStartLoad(
+  yyjson_val *itemObj,
+  cutsceneitem_t *item
+) {
+  yyjson_val *enemies = yyjson_obj_get(itemObj, "enemies");
+  size_t enemyCount = yyjson_arr_size(enemies);
+  if(
+    !yyjson_is_arr(enemies) || enemyCount == 0 ||
+    enemyCount > CUTSCENE_BATTLE_START_ENEMY_COUNT_MAX
+  ) {
+    errorThrow(
+      "Cutscene item (BATTLE_START): 'enemies' must have 1-%u entries",
+      (uint32_t)CUTSCENE_BATTLE_START_ENEMY_COUNT_MAX
+    );
+  }
+  item->battleStart.enemyCount = (uint8_t)enemyCount;
+
+  yyjson_arr_iter iter = yyjson_arr_iter_with(enemies);
+  yyjson_val *enemyVal;
+  size_t e = 0;
+  while((enemyVal = yyjson_arr_iter_next(&iter)) != NULL) {
+    cutscenebattlestartenemy_t *enemy = &item->battleStart.enemies[e];
+
+    yyjson_val *stats = yyjson_obj_get(enemyVal, "stats");
+    if(!yyjson_is_obj(stats)) {
+      errorThrow(
+        "Cutscene item (BATTLE_START): enemies[%u] is missing 'stats'",
+        (uint32_t)e
+      );
+    }
+    enemy->stats.attack = (uint16_t)yyjson_get_int(yyjson_obj_get(stats, "attack"));
+    enemy->stats.defense = (uint16_t)yyjson_get_int(yyjson_obj_get(stats, "defense"));
+    enemy->stats.magic = (uint16_t)yyjson_get_int(yyjson_obj_get(stats, "magic"));
+    enemy->stats.speed = (uint16_t)yyjson_get_int(yyjson_obj_get(stats, "speed"));
+    enemy->stats.luck = (uint16_t)yyjson_get_int(yyjson_obj_get(stats, "luck"));
+    enemy->stats.healthMax = (uint16_t)yyjson_get_int(yyjson_obj_get(stats, "healthMax"));
+    enemy->stats.mpMax = (uint16_t)yyjson_get_int(yyjson_obj_get(stats, "mpMax"));
+
+    yyjson_val *abilities = yyjson_obj_get(enemyVal, "abilities");
+    if(abilities != NULL) {
+      size_t abilityCount = yyjson_arr_size(abilities);
+      if(
+        !yyjson_is_arr(abilities) ||
+        abilityCount > BATTLE_FIGHTER_ABILITY_COUNT_MAX
+      ) {
+        errorThrow(
+          "Cutscene item (BATTLE_START): enemies[%u].abilities must have "
+          "0-%u entries",
+          (uint32_t)e, (uint32_t)BATTLE_FIGHTER_ABILITY_COUNT_MAX
+        );
+      }
+
+      yyjson_arr_iter abilityIter = yyjson_arr_iter_with(abilities);
+      yyjson_val *abilityVal;
+      size_t a = 0;
+      while((abilityVal = yyjson_arr_iter_next(&abilityIter)) != NULL) {
+        const char_t *name = yyjson_get_str(abilityVal);
+        battlemoveid_t ability = name == NULL
+          ? BATTLE_MOVE_ID_NULL : battleMoveGetIdByName(name);
+        if(ability == BATTLE_MOVE_ID_NULL) {
+          errorThrow(
+            "Cutscene item (BATTLE_START): enemies[%u].abilities[%u] is "
+            "invalid",
+            (uint32_t)e, (uint32_t)a
+          );
+        }
+        enemy->abilities[a] = ability;
+        a++;
+      }
+      enemy->abilityCount = (uint8_t)abilityCount;
+    }
+
+    e++;
+  }
+
+  errorOk();
+}

src/dusk/rpg/cutscene/item/battle/cutscenebattlestart.h

@@ -0,0 +1,62 @@
+/**
+ * Copyright (c) 2026 Dominic Masters
+ *
+ * This software is released under the MIT License.
+ * https://opensource.org/licenses/MIT
+ */
+
+#pragma once
+#include "rpg/battle/fighter/battlefighter.h"
+#include "rpg/cutscene/item/cutsceneitembase.h"
+
+// Enemies always occupy the left-side positions (BATTLE_FIGHTER_POS_0-3).
+#define CUTSCENE_BATTLE_START_ENEMY_COUNT_MAX 4
+
+typedef struct {
+  battlefighterstats_t stats;
+  battlemoveid_t abilities[BATTLE_FIGHTER_ABILITY_COUNT_MAX];
+  uint8_t abilityCount;
+} cutscenebattlestartenemy_t;
+
+typedef struct {
+  cutscenebattlestartenemy_t enemies[CUTSCENE_BATTLE_START_ENEMY_COUNT_MAX];
+  uint8_t enemyCount;
+} cutscenebattlestart_t;
+
+/**
+ * Starts a BATTLE_START item: spawns the configured enemies, fills the
+ * remaining positions with the active party (via partyGetOrderMember), and
+ * calls battleStart. Always completes immediately - the battle scene takes
+ * over from here.
+ *
+ * @param item The cutscene item.
+ * @param data Runtime data storage.
+ */
+void cutsceneBattleStartStart(
+  const cutsceneitem_t *item,
+  cutsceneitemdata_t *data
+);
+
+/**
+ * Updates a BATTLE_START item (always completes immediately).
+ *
+ * @param item The cutscene item.
+ * @param data Runtime data storage.
+ * @returns true always.
+ */
+bool_t cutsceneBattleStartUpdate(
+  const cutsceneitem_t *item,
+  cutsceneitemdata_t *data
+);
+
+/**
+ * Parses a BATTLE_START cutscene item's JSON fields into item.
+ *
+ * @param itemObj The item's JSON object.
+ * @param item Destination item, already zeroed by the caller.
+ * @return Error code indicating success or failure of the parse.
+ */
+errorret_t cutsceneBattleStartLoad(
+  yyjson_val *itemObj,
+  cutsceneitem_t *item
+);

src/dusk/rpg/cutscene/item/battle/cutscenebattlewaitselection.c

@@ -0,0 +1,16 @@
+/**
+ * Copyright (c) 2026 Dominic Masters
+ *
+ * This software is released under the MIT License.
+ * https://opensource.org/licenses/MIT
+ */
+
+#include "rpg/cutscene/item/cutsceneitem.h"
+#include "rpg/battle/battle.h"
+
+bool_t cutsceneBattleWaitSelectionUpdate(
+  const cutsceneitem_t *item,
+  cutsceneitemdata_t *data
+) {
+  return BATTLE.state != BATTLE_STATE_SELECTION;
+}

src/dusk/rpg/cutscene/item/battle/cutscenebattlewaitselection.h

@@ -0,0 +1,25 @@
+/**
+ * Copyright (c) 2026 Dominic Masters
+ *
+ * This software is released under the MIT License.
+ * https://opensource.org/licenses/MIT
+ */
+
+#pragma once
+#include "rpg/cutscene/item/cutsceneitembase.h"
+
+/**
+ * Updates a BATTLE_WAIT_SELECTION step, completing once the battle is no
+ * longer in BATTLE_STATE_SELECTION -- i.e. every fighter has decided a
+ * move (moving on to BATTLE_STATE_EXECUTING) or the selecting fighter has
+ * fled (moving on to BATTLE_STATE_FLED). Has no Start callback -- there's
+ * nothing to do until selection actually finishes.
+ *
+ * @param item The cutscene item.
+ * @param data Runtime data storage.
+ * @returns true once BATTLE.state is no longer BATTLE_STATE_SELECTION.
+ */
+bool_t cutsceneBattleWaitSelectionUpdate(
+  const cutsceneitem_t *item,
+  cutsceneitemdata_t *data
+);

src/dusk/rpg/cutscene/item/cutsceneitem.c

@@ -244,6 +244,27 @@ cutsceneitemcallbacks_t CUTSCENE_ITEM_CALLBACKS[CUTSCENE_ITEM_TYPE_COUNT] = {
     .load = cutsceneMapAreaWaitLoad
   },
 
+  // Battle
+  [CUTSCENE_ITEM_TYPE_BATTLE_START] = {
+    .init = cutsceneBattleStartStart,
+    .update = cutsceneBattleStartUpdate,
+    .jsonName = "BATTLE_START",
+    .load = cutsceneBattleStartLoad
+  },
+
+  [CUTSCENE_ITEM_TYPE_BATTLE_SET_STATE] = {
+    .init = cutsceneBattleSetStateStart,
+    .update = cutsceneBattleSetStateUpdate,
+    .jsonName = "BATTLE_SET_STATE",
+    .load = cutsceneBattleSetStateLoad
+  },
+
+  [CUTSCENE_ITEM_TYPE_BATTLE_WAIT_SELECTION] = {
+    .update = cutsceneBattleWaitSelectionUpdate,
+    .jsonName = "BATTLE_WAIT_SELECTION",
+    .load = cutsceneItemLoadNoop
+  },
+
   // Save
   [CUTSCENE_ITEM_TYPE_SAVE_DEVICE_CHECK] = {
     .init = cutsceneSaveDeviceCheckStart,

src/dusk/rpg/cutscene/item/cutsceneitem.h

@@ -40,6 +40,9 @@
 #include "maparea/cutscenemapareaadd.h"
 #include "maparea/cutscenemaparearemove.h"
 #include "maparea/cutscenemapareawait.h"
+#include "battle/cutscenebattlestart.h"
+#include "battle/cutscenebattlesetstate.h"
+#include "battle/cutscenebattlewaitselection.h"
 #include "save/cutscenesavedevicecheck.h"
 #include "save/cutscenesaveloadallslots.h"
 #include "audio/cutsceneaudioplay.h"
@@ -112,6 +115,8 @@ struct cutsceneitem_s {
     cutscenemapareaadd_t mapAreaAdd;
     cutscenemaparearemove_t mapAreaRemove;
     cutscenemapareawait_t mapAreaWait;
+    cutscenebattlestart_t battleStart;
+    cutscenebattlesetstate_t battleSetState;
     cutsceneemoji_t emoji;
     cutsceneshake_t shake;
     cutscenemodal_t modal;

src/dusk/rpg/cutscene/item/cutsceneitembase.h

@@ -59,6 +59,11 @@ typedef enum {
   CUTSCENE_ITEM_TYPE_MAP_AREA_REMOVE,
   CUTSCENE_ITEM_TYPE_MAP_AREA_WAIT,
 
+  // Battle
+  CUTSCENE_ITEM_TYPE_BATTLE_START,
+  CUTSCENE_ITEM_TYPE_BATTLE_SET_STATE,
+  CUTSCENE_ITEM_TYPE_BATTLE_WAIT_SELECTION,
+
   // Save
   CUTSCENE_ITEM_TYPE_SAVE_DEVICE_CHECK,
   CUTSCENE_ITEM_TYPE_SAVE_LOAD_ALL_SLOTS,

src/dusk/rpg/cutscene/item/json/CMakeLists.txt

@@ -14,6 +14,7 @@ target_sources(${DUSK_LIBRARY_TARGET_NAME}
     cutscenejsonemoji.c
     cutscenejsonentitytype.c
     cutscenejsonentitydir.c
+    cutscenejsonbattlestate.c
     cutscenejsonscenetype.c
     cutscenejsonuiscreentype.c
     cutscenejsonaudiochannel.c

src/dusk/rpg/cutscene/item/json/cutscenejsonbattlestate.c

@@ -0,0 +1,38 @@
+/**
+ * Copyright (c) 2026 Dominic Masters
+ *
+ * This software is released under the MIT License.
+ * https://opensource.org/licenses/MIT
+ */
+
+#include "cutscenejsonbattlestate.h"
+#include "cutscenejsonenum.h"
+
+static const cutscenejsonenumentry_t CUTSCENE_JSON_BATTLE_STATE_TABLE[] = {
+  { "OPENING", BATTLE_STATE_OPENING },
+  { "PRE_ROUND", BATTLE_STATE_PRE_ROUND },
+  { "SELECTION", BATTLE_STATE_SELECTION },
+  { "EXECUTING", BATTLE_STATE_EXECUTING },
+  { "POST_ROUND", BATTLE_STATE_POST_ROUND },
+  { "LOST", BATTLE_STATE_LOST },
+  { "WON", BATTLE_STATE_WON },
+  { "FLED", BATTLE_STATE_FLED },
+  { "ENDING", BATTLE_STATE_ENDING },
+};
+#define CUTSCENE_JSON_BATTLE_STATE_TABLE_COUNT \
+  (sizeof(CUTSCENE_JSON_BATTLE_STATE_TABLE) / sizeof(cutscenejsonenumentry_t))
+
+bool_t cutsceneJsonLookupBattleState(
+  const char_t *name,
+  battlestate_t *out
+) {
+  int32_t value;
+  if(!cutsceneJsonLookupEnumInsensitive(
+    CUTSCENE_JSON_BATTLE_STATE_TABLE,
+    CUTSCENE_JSON_BATTLE_STATE_TABLE_COUNT, name, &value
+  )) {
+    return false;
+  }
+  *out = (battlestate_t)value;
+  return true;
+}

src/dusk/rpg/cutscene/item/json/cutscenejsonbattlestate.h

@@ -0,0 +1,21 @@
+/**
+ * Copyright (c) 2026 Dominic Masters
+ *
+ * This software is released under the MIT License.
+ * https://opensource.org/licenses/MIT
+ */
+
+#pragma once
+#include "rpg/battle/state/battlestate.h"
+
+/**
+ * Looks up name (case-insensitive) against every battlestate_t name.
+ *
+ * @param name Name to search for.
+ * @param out Set to the matching state on success.
+ * @return true if a matching entry was found, false otherwise.
+ */
+bool_t cutsceneJsonLookupBattleState(
+  const char_t *name,
+  battlestate_t *out
+);

src/dusk/scene/battle/scenebattle.c

@@ -6,6 +6,7 @@
  */
 
 #include "scenebattle.h"
+#include "assert/assert.h"
 #include "display/display.h"
 #include "display/displaystate.h"
 #include "display/shader/shader.h"
@@ -80,6 +81,10 @@ void sceneBattleWorldToScreen(
   vec3 renderPos,
   vec2 out
 ) {
+  assertNotNull(battle, "battle cannot be NULL");
+  assertNotNull(renderPos, "renderPos cannot be NULL");
+  assertNotNull(out, "out cannot be NULL");
+
   mat4 viewProj;
   glm_mat4_mul(battle->projection, battle->eye, viewProj);
 
@@ -94,15 +99,20 @@ void sceneBattleWorldToScreen(
 }
 
 void sceneBattleGetFighterPosition(const uint8_t fighterIndex, vec3 out) {
+  assertTrue(fighterIndex < BATTLE_FIGHTER_POS_COUNT, "fighterIndex out of bounds");
   const battlefighter_t *fighter = BATTLE.fighters[fighterIndex];
+  assertNotNull(fighter, "Fighter cannot be NULL");
+  assertNotNull(out, "out cannot be NULL");
 
   // Ordinal (and count) of this fighter among its living-slot teammates,
   // in slot order, so each team lays out as an evenly spaced row.
   uint8_t ordinal = 0;
   uint8_t teamCount = 0;
   for(uint8_t i = 0; i < BATTLE_FIGHTER_POS_COUNT; i++) {
-    if(BATTLE.fighters[i]->status == BATTLE_FIGHTER_STATUS_NULL) continue;
-    if(BATTLE.fighters[i]->team != fighter->team) continue;
+    const battlefighter_t *candidate = BATTLE.fighters[i];
+    if(candidate == NULL) continue;
+    if(candidate->status == BATTLE_FIGHTER_STATUS_NULL) continue;
+    if(candidate->team != fighter->team) continue;
     if(i < fighterIndex) ordinal++;
     teamCount++;
   }
@@ -119,7 +129,9 @@ void sceneBattleGetFighterPosition(const uint8_t fighterIndex, vec3 out) {
 }
 
 errorret_t sceneBattleDrawFighter(const uint8_t fighterIndex) {
+  assertTrue(fighterIndex < BATTLE_FIGHTER_POS_COUNT, "fighterIndex out of bounds");
   const battlefighter_t *fighter = BATTLE.fighters[fighterIndex];
+  if(fighter == NULL) errorOk();
   if(fighter->status == BATTLE_FIGHTER_STATUS_NULL) errorOk();
 
   vec3 position;

src/dusk/ui/screen/battle/uibattlehud.c

@@ -42,12 +42,13 @@ errorret_t uiBattleHudInit(void) {
 }
 
 errorret_t uiBattleHudDraw(void) {
-  if(BATTLE.state == BATTLE_STATE_NONE) errorOk();
+  if(BATTLE.state == BATTLE_STATE_NULL) errorOk();
 
   scenebattle_t *battle = &SCENE.data.battle;
 
   for(uint8_t i = 0; i < BATTLE_FIGHTER_POS_COUNT; i++) {
     const battlefighter_t *fighter = BATTLE.fighters[i];
+    if(fighter == NULL) continue;
     if(fighter->status == BATTLE_FIGHTER_STATUS_NULL) continue;
 
     vec3 position;

src/dusk/ui/screen/battle/uibattlemenu.c

@@ -22,13 +22,14 @@ void uiBattleMenuTargetSelected(
   const uint8_t index,
   const uimenuitem_t *item
 ) {
-  battlePlayerAttack(UI_BATTLE_MENU.targetFighterIndex[index]);
+  assertTrue(index < UI_BATTLE_MENU_TARGET_ITEM_COUNT, "index out of bounds");
+  battleStateSelectionPlayerAttack(UI_BATTLE_MENU.targetFighterIndex[index]);
   uiMenuClose(&UI_BATTLE_MENU.targetMenu);
   uiMenuClose(&UI_BATTLE_MENU.actionMenu);
 }
 
 void uiBattleMenuOpenTargets(void) {
-  battlefighter_t *current = battleGetCurrentFighter();
+  battlefighter_t *current = battleStateSelectionGetCurrentFighter();
   if(current == NULL) return;
 
   const battlefighterteam_t enemyTeam =
@@ -42,6 +43,7 @@ void uiBattleMenuOpenTargets(void) {
 
   for(uint8_t i = 0; i < BATTLE_FIGHTER_POS_COUNT; i++) {
     battlefighter_t *candidate = BATTLE.fighters[i];
+    if(candidate == NULL) continue;
     if(candidate->team != enemyTeam) continue;
     if(!battleFighterIsAlive(candidate)) continue;
 
@@ -71,7 +73,7 @@ void uiBattleMenuActionSelected(
       break;
 
     case UI_BATTLE_MENU_ACTION_INDEX_FLEE:
-      battlePlayerFlee();
+      battleStateSelectionPlayerFlee();
       uiMenuClose(&UI_BATTLE_MENU.actionMenu);
       break;
 
@@ -116,7 +118,7 @@ errorret_t uiBattleMenuInit(void) {
 errorret_t uiBattleMenuUpdate(void) {
   if(uiMenuIsActive(&UI_BATTLE_MENU.actionMenu)) errorOk();
 
-  battlefighter_t *current = battleGetCurrentFighter();
+  battlefighter_t *current = battleStateSelectionGetCurrentFighter();
   if(current == NULL) errorOk();
   if(current->controller != BATTLE_FIGHTER_CONTROLLER_PLAYER) errorOk();