offline movements

backend/cmd/server/main.go

@@ -119,6 +119,8 @@ func main() {
 		}
 		hub.SendToHero(heroID, "adventure_log_line", line)
 	})
+	engine.SetDigestStore(digestStore)
+	engine.SetHeroSubscriber(hub.IsHeroConnected)
 
 	// Hub callbacks: on connect, load hero and register movement; on disconnect, persist.
 	hub.OnConnect = func(heroID int64) {
@@ -130,11 +132,12 @@ func main() {
 		engine.RegisterHeroMovement(hero)
 	}
 	hub.OnDisconnect = func(heroID int64, remainingSameHero int) {
-		engine.HeroSocketDetached(heroID, remainingSameHero == 0)
+		disconnectAt := time.Now()
+		engine.HeroSocketDetached(heroID, remainingSameHero == 0, disconnectAt)
 		if remainingSameHero == 0 {
 			dctx, cancel := context.WithTimeout(context.Background(), 3*time.Second)
 			defer cancel()
-			if err := heroStore.SetWsDisconnectedAt(dctx, heroID, time.Now()); err != nil {
+			if err := heroStore.SetWsDisconnectedAt(dctx, heroID, disconnectAt); err != nil {
 				logger.Warn("set ws_disconnected_at", "hero_id", heroID, "error", err)
 			}
 		}
@@ -177,24 +180,20 @@ func main() {
 		}
 	}()
 
-	// Start game engine.
-	go func() {
-		if err := engine.Run(ctx); err != nil && err != context.Canceled {
-			logger.Error("game engine error", "error", err)
-		}
-	}()
-
 	// Record server start time for catch-up gap calculation.
 	serverStartedAt := time.Now()
-	offlineSim := game.NewOfflineSimulator(heroStore, logStore, questStore, roadGraph, logger, func() bool {
-		return engine.IsTimePaused()
-	}, engine.HeroHasActiveMovement).
+	bootstrapSim := game.NewOfflineSimulator(heroStore, logStore, questStore, roadGraph, logger, nil, nil).
 		WithCombatTickRate(engine.TickRate()).
 		WithRewardStores(gearStore, achievementStore, taskStore).
 		WithDigestStore(digestStore)
+	bootCtx, bootCancel := context.WithTimeout(ctx, 3*time.Minute)
+	game.BootstrapResidentHeroes(bootCtx, engine, heroStore, bootstrapSim, 500, logger)
+	bootCancel()
+
+	// Start game engine (after resident heroes are registered).
 	go func() {
-		if err := offlineSim.Run(ctx); err != nil && err != context.Canceled {
-			logger.Error("offline simulator error", "error", err)
+		if err := engine.Run(ctx); err != nil && err != context.Canceled {
+			logger.Error("game engine error", "error", err)
 		}
 	}()
 

backend/internal/game/engine.go

@@ -77,8 +77,17 @@ type Engine struct {
 
 	// npcAlmsHandler runs when the client accepts a wandering merchant offer (WS).
 	npcAlmsHandler func(context.Context, int64) error
+
+	digestStore *storage.OfflineDigestStore
+	// heroSubscriber reports whether the hero has at least one WebSocket client (optional).
+	heroSubscriber func(heroID int64) bool
+	// lastDisconnectedFullSave tracks periodic DB full saves for heroes without a WS subscriber.
+	lastDisconnectedFullSave map[int64]time.Time
 }
 
+// offlineDisconnectedFullSaveInterval is how often we persist a full hero row when no WS client is connected.
+const offlineDisconnectedFullSaveInterval = 30 * time.Second
+
 // NewEngine creates a new game engine with the given tick rate.
 func NewEngine(tickRate time.Duration, eventCh chan model.CombatEvent, logger *slog.Logger) *Engine {
 	e := &Engine{
@@ -89,6 +98,7 @@ func NewEngine(tickRate time.Duration, eventCh chan model.CombatEvent, logger *s
 		incomingCh:                 make(chan IncomingMessage, 256),
 		eventCh:                    eventCh,
 		logger:                     logger,
+		lastDisconnectedFullSave:   make(map[int64]time.Time),
 	}
 	heap.Init(&e.queue)
 	return e
@@ -98,7 +108,24 @@ func (e *Engine) GetMovements(heroId int64) *HeroMovement {
 	return e.movements[heroId]
 }
 
-// HeroHasActiveMovement is true while the hero has an in-engine movement session (typically WebSocket-connected).
+// MergeResidentHeroState copies the authoritative in-engine hero into dst after SyncToHero.
+// Returns false if the hero is not resident. Used by REST init so the client sees the same state the Engine simulates.
+func (e *Engine) MergeResidentHeroState(dst *model.Hero) bool {
+	if dst == nil {
+		return false
+	}
+	e.mu.RLock()
+	hm := e.movements[dst.ID]
+	e.mu.RUnlock()
+	if hm == nil || hm.Hero == nil {
+		return false
+	}
+	hm.SyncToHero()
+	*dst = *hm.Hero
+	return true
+}
+
+// HeroHasActiveMovement is true while the hero has an in-engine movement session (resident world actor).
 func (e *Engine) HeroHasActiveMovement(heroID int64) bool {
 	e.mu.RLock()
 	defer e.mu.RUnlock()
@@ -272,6 +299,28 @@ func (e *Engine) SetAdventureLog(w AdventureLogWriter) {
 	e.adventureLog = w
 }
 
+// SetDigestStore wires persistent offline digest accumulation (after disconnect grace).
+func (e *Engine) SetDigestStore(d *storage.OfflineDigestStore) {
+	e.mu.Lock()
+	defer e.mu.Unlock()
+	e.digestStore = d
+}
+
+// SetHeroSubscriber sets an optional callback: return true if the hero has at least one WebSocket client.
+// Used for periodic full saves when the world keeps simulating without a subscriber.
+func (e *Engine) SetHeroSubscriber(fn func(heroID int64) bool) {
+	e.mu.Lock()
+	defer e.mu.Unlock()
+	e.heroSubscriber = fn
+}
+
+func (e *Engine) applyOfflineDigest(ctx context.Context, heroID int64, hero *model.Hero, now time.Time, delta storage.OfflineDigestDelta) {
+	if e.digestStore == nil || hero == nil || !OfflineDigestCollecting(hero.WsDisconnectedAt, now) {
+		return
+	}
+	_ = e.digestStore.ApplyDelta(ctx, heroID, delta)
+}
+
 // IncomingCh returns the channel for routing client WS commands into the engine.
 func (e *Engine) IncomingCh() chan<- IncomingMessage {
 	return e.incomingCh
@@ -594,6 +643,7 @@ func (e *Engine) RegisterHeroMovement(hero *model.Hero) {
 	// Reconnect while the previous socket is still tearing down: keep live movement so we
 	// do not replace (x,y) and route with a stale DB snapshot.
 	if existing, ok := e.movements[hero.ID]; ok {
+		existing.Hero.WsDisconnectedAt = hero.WsDisconnectedAt
 		existing.Hero.EnsureGearMap()
 		existing.Hero.RefreshDerivedCombatStats(now)
 		e.logger.Info("hero movement reattached (existing session)",
@@ -621,6 +671,19 @@ func (e *Engine) RegisterHeroMovement(hero *model.Hero) {
 	hm.MarkTownPausePersisted(hm.townPausePersistSignature())
 	hm.SyncToHero()
 
+	// DB said fighting but engine has no combat (e.g. after restart): attach a new encounter.
+	if hm.State == model.StateFighting {
+		if _, exists := e.combats[hero.ID]; !exists {
+			en := PickEnemyForLevel(hero.Level)
+			if en.Slug != "" {
+				e.startCombatLocked(hm.Hero, &en)
+			} else {
+				hm.State = model.StateWalking
+				hm.Hero.State = model.StateWalking
+			}
+		}
+	}
+
 	e.logger.Info("hero movement registered",
 		"hero_id", hero.ID,
 		"state", hm.State,
@@ -647,15 +710,16 @@ func (e *Engine) RegisterHeroMovement(hero *model.Hero) {
 	}
 }
 
-// HeroSocketDetached persists hero state on every WS disconnect and removes in-memory
-// movement only when lastConnection is true (no other tabs/sockets for this hero).
-func (e *Engine) HeroSocketDetached(heroID int64, lastConnection bool) {
+// HeroSocketDetached persists hero state on every WS disconnect. Movement and combat stay in the engine
+// so the world keeps simulating; disconnectedAt is stored on the in-memory hero for offline digest timing.
+func (e *Engine) HeroSocketDetached(heroID int64, lastConnection bool, disconnectedAt time.Time) {
 	e.mu.Lock()
 	hm, ok := e.movements[heroID]
 	if ok {
 		hm.SyncToHero()
-		if lastConnection {
-			delete(e.movements, heroID)
+		if lastConnection && !disconnectedAt.IsZero() && hm.Hero != nil {
+			t := disconnectedAt
+			hm.Hero.WsDisconnectedAt = &t
 		}
 	}
 	var heroSnap *model.Hero
@@ -1225,11 +1289,15 @@ func (e *Engine) GetCombat(heroID int64) (*model.CombatState, bool) {
 	return cs, ok
 }
 
-// processCombatTick is the 100ms combat processing tick.
+// processCombatTick is the combat processing tick (typically 100ms cadence).
 func (e *Engine) processCombatTick(now time.Time) {
 	e.mu.Lock()
 	defer e.mu.Unlock()
+	e.processCombatTickLocked(now)
+}
 
+// processCombatTickLocked runs combat logic; caller must hold e.mu.
+func (e *Engine) processCombatTickLocked(now time.Time) {
 	// Heroes resting or touring town must not keep fighting in the background.
 	var purgeCombat []int64
 	for heroID := range e.combats {
@@ -1299,6 +1367,9 @@ func (e *Engine) processCombatTick(now time.Time) {
 			if hm, ok := e.movements[heroID]; ok {
 				hm.Die()
 			}
+			dctx, cancel := context.WithTimeout(context.Background(), 2*time.Second)
+			e.applyOfflineDigest(dctx, heroID, cs.Hero, now, storage.OfflineDigestDelta{Deaths: 1})
+			cancel()
 			delete(e.combats, heroID)
 		}
 	}
@@ -1462,6 +1533,9 @@ func (e *Engine) processEnemyAttack(cs *model.CombatState, now time.Time) {
 		if hm, ok := e.movements[cs.HeroID]; ok {
 			hm.Die()
 		}
+		dctx, cancel := context.WithTimeout(context.Background(), 2*time.Second)
+		e.applyOfflineDigest(dctx, cs.HeroID, cs.Hero, now, storage.OfflineDigestDelta{Deaths: 1})
+		cancel()
 		delete(e.combats, cs.HeroID)
 
 		e.logger.Info("hero died",
@@ -1515,6 +1589,18 @@ func (e *Engine) handleEnemyDeath(cs *model.CombatState, now time.Time) {
 		victoryDrops = e.onEnemyDeath(hero, enemy, now)
 	}
 
+	if hero != nil {
+		dctx, cancel := context.WithTimeout(context.Background(), 2*time.Second)
+		e.applyOfflineDigest(dctx, cs.HeroID, hero, now, storage.OfflineDigestDelta{
+			MonstersKilled: 1,
+			XPGained:       enemy.XPReward,
+			GoldGained:     model.SumGoldFromLootDrops(victoryDrops),
+			LevelsGained:   hero.Level - oldLevel,
+			LootAppend:     NonGoldLootForDigest(victoryDrops),
+		})
+		cancel()
+	}
+
 	e.emitEvent(model.CombatEvent{
 		Type:      "combat_end",
 		HeroID:    cs.HeroID,
@@ -1572,6 +1658,50 @@ func (e *Engine) handleEnemyDeath(cs *model.CombatState, now time.Time) {
 	)
 }
 
+// processAutoReviveLocked revives dead heroes after AutoReviveAfterMs downtime. Caller holds e.mu.
+func (e *Engine) processAutoReviveLocked(now time.Time) {
+	if e.heroStore == nil {
+		return
+	}
+	gap := time.Duration(tuning.Get().AutoReviveAfterMs) * time.Millisecond
+	for heroID, hm := range e.movements {
+		if hm == nil || hm.Hero == nil {
+			continue
+		}
+		h := hm.Hero
+		if h.State != model.StateDead && h.HP > 0 {
+			continue
+		}
+		if now.Sub(h.UpdatedAt) <= gap {
+			continue
+		}
+		h.HP = int(float64(h.MaxHP) * tuning.Get().ReviveHpPercent)
+		if h.HP < 1 {
+			h.HP = 1
+		}
+		h.State = model.StateWalking
+		h.Debuffs = nil
+		hm.State = model.StateWalking
+		hm.SyncToHero()
+		dctx, cancel := context.WithTimeout(context.Background(), 2*time.Second)
+		e.applyOfflineDigest(dctx, heroID, h, now, storage.OfflineDigestDelta{Revives: 1})
+		cancel()
+		if e.adventureLog != nil {
+			e.adventureLog(heroID, model.AdventureLogLine{
+				Event: &model.AdventureLogEvent{
+					Code: model.LogAutoReviveAfterSec,
+					Args: map[string]any{"seconds": int64(gap.Round(time.Second) / time.Second)},
+				},
+			})
+		}
+		ctx, cancelSave := context.WithTimeout(context.Background(), 5*time.Second)
+		if err := e.heroStore.Save(ctx, h); err != nil && e.logger != nil {
+			e.logger.Error("persist hero after auto-revive", "hero_id", heroID, "error", err)
+		}
+		cancelSave()
+	}
+}
+
 // processMovementTick advances all walking heroes and checks for encounters.
 // Runs on the configured movement cadence.
 func (e *Engine) processMovementTick(now time.Time) {
@@ -1582,6 +1712,8 @@ func (e *Engine) processMovementTick(now time.Time) {
 		return
 	}
 
+	e.processAutoReviveLocked(now)
+
 	startCombat := func(hm *HeroMovement, enemy *model.Enemy, t time.Time) {
 		e.startCombatLocked(hm.Hero, enemy)
 	}
@@ -1612,6 +1744,21 @@ func (e *Engine) processMovementTick(now time.Time) {
 			hm.MarkTownPausePersisted(sig)
 			e.syncTownSessionRedis(heroID, hm)
 		}
+		if e.heroStore != nil && e.heroSubscriber != nil && hm.Hero != nil && !e.heroSubscriber(heroID) {
+			last := e.lastDisconnectedFullSave[heroID]
+			if last.IsZero() || now.Sub(last) >= offlineDisconnectedFullSaveInterval {
+				hm.SyncToHero()
+				ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
+				if err := e.heroStore.Save(ctx, hm.Hero); err != nil {
+					if e.logger != nil {
+						e.logger.Error("persist disconnected resident hero", "hero_id", heroID, "error", err)
+					}
+				} else {
+					e.lastDisconnectedFullSave[heroID] = now
+				}
+				cancel()
+			}
+		}
 	}
 }
 

backend/internal/game/offline.go

@@ -13,9 +13,19 @@ import (
 	"github.com/denisovdennis/autohero/internal/tuning"
 )
 
-// OfflineSimulator runs periodic background ticks for heroes that are offline,
-// advancing movement the same way as the online engine (without WebSocket payloads)
-// and resolving random encounters with SimulateOneFight.
+// OfflineDigestGrace is the delay after the last WS disconnect before offline events count toward the digest.
+const OfflineDigestGrace = 30 * time.Second
+
+// OfflineDigestCollecting is true when digest deltas should be applied (disconnect + grace elapsed).
+func OfflineDigestCollecting(disconnect *time.Time, now time.Time) bool {
+	if disconnect == nil {
+		return false
+	}
+	return !now.Before(disconnect.Add(OfflineDigestGrace))
+}
+
+// OfflineSimulator holds dependencies for one-shot wall-time catch-up (server downtime, cold-start bootstrap).
+// Live progression runs in the Engine for all resident heroes.
 type OfflineSimulator struct {
 	store          *storage.HeroStore
 	logStore       *storage.LogStore
@@ -35,9 +45,8 @@ type OfflineSimulator struct {
 	digestStore *storage.OfflineDigestStore
 }
 
-// NewOfflineSimulator creates a new OfflineSimulator that ticks every 30 seconds.
-// isPaused may be nil; if it returns true, offline catch-up is skipped (aligned with engine pause).
-// skipIfLive may be nil; if it returns true for a hero id, that hero is skipped this tick.
+// NewOfflineSimulator builds a catch-up runner used by BootstrapResidentHeroes and REST init gap recovery.
+// isPaused and skipIfLive are optional filters for SimulateHeroAt callers; Run() is a no-op.
 func NewOfflineSimulator(store *storage.HeroStore, logStore *storage.LogStore, questStore *storage.QuestStore, graph *RoadGraph, logger *slog.Logger, isPaused func() bool, skipIfLive func(heroID int64) bool) *OfflineSimulator {
 	return &OfflineSimulator{
 		store:          store,
@@ -75,8 +84,8 @@ func (s *OfflineSimulator) WithDigestStore(d *storage.OfflineDigestStore) *Offli
 	return s
 }
 
-// nonGoldLootForDigest keeps equipment/potion lines only; gold belongs in gold_gained counter.
-func nonGoldLootForDigest(drops []model.LootDrop) []model.LootDrop {
+// NonGoldLootForDigest keeps equipment/potion lines only; gold belongs in gold_gained counter.
+func NonGoldLootForDigest(drops []model.LootDrop) []model.LootDrop {
 	if len(drops) == 0 {
 		return nil
 	}
@@ -93,58 +102,18 @@ func nonGoldLootForDigest(drops []model.LootDrop) []model.LootDrop {
 	return out
 }
 
-// Run starts the offline simulation loop. It blocks until the context is cancelled.
+// Run is a no-op waiter: progression runs in the game Engine for all resident heroes.
+// Kept so callers can block on the same context lifecycle as before.
 func (s *OfflineSimulator) Run(ctx context.Context) error {
-	ticker := time.NewTicker(s.interval)
-	defer ticker.Stop()
-
-	s.logger.Info("offline simulator started", "interval", s.interval)
-
-	for {
-		select {
-		case <-ctx.Done():
-			s.logger.Info("offline simulator shutting down")
-			return ctx.Err()
-		case <-ticker.C:
-			s.processTick(ctx)
-		}
-	}
-}
-
-// processTick finds all offline heroes and simulates one fight for each.
-func (s *OfflineSimulator) processTick(ctx context.Context) {
-	if s.isPaused != nil && s.isPaused() {
-		return
-	}
-	heroes, err := s.store.ListOfflineHeroes(ctx, s.interval*2, 100)
-	if err != nil {
-		s.logger.Error("offline simulator: failed to list offline heroes", "error", err)
-		return
-	}
-
-	if len(heroes) == 0 {
-		return
-	}
-
-	s.logger.Debug("offline simulator tick", "offline_heroes", len(heroes))
-
-	for _, hero := range heroes {
-		if s.skipIfLive != nil && s.skipIfLive(hero.ID) {
-			continue
-		}
-		if err := s.simulateHeroTick(ctx, hero, time.Now(), true); err != nil {
-			s.logger.Error("offline simulator: hero tick failed",
-				"hero_id", hero.ID,
-				"error", err,
-			)
-			// Continue with other heroes — don't crash on one failure.
-		}
+	<-ctx.Done()
+	if s.logger != nil {
+		s.logger.Info("offline simulator stub shutting down (engine-authoritative world)")
 	}
+	return ctx.Err()
 }
 
 // simulateHeroTick catches up movement in configured movement-tick steps from hero.UpdatedAt to now,
-// then persists. Random encounters use the same rolls as online; combat is resolved
-// synchronously via SimulateOneFight (no WebSocket).
+// then persists. Encounters resolve combat via SimulateOneFight (batch-only; live play uses Engine combat).
 func (s *OfflineSimulator) simulateHeroTick(ctx context.Context, hero *model.Hero, now time.Time, persist bool) error {
 
 	// Auto-revive after configured downtime (autoReviveAfterMs).
@@ -162,7 +131,7 @@ func (s *OfflineSimulator) simulateHeroTick(ctx context.Context, hero *model.Her
 				Args: map[string]any{"seconds": int64(gap.Round(time.Second) / time.Second)},
 			},
 		})
-		if s.digestStore != nil {
+		if s.digestStore != nil && OfflineDigestCollecting(hero.WsDisconnectedAt, now) {
 			_ = s.digestStore.ApplyDelta(ctx, hero.ID, storage.OfflineDigestDelta{Revives: 1})
 		}
 	}
@@ -198,7 +167,7 @@ func (s *OfflineSimulator) simulateHeroTick(ctx context.Context, hero *model.Her
 		rewardDeps := s.rewardDeps(tickNow)
 		levelBefore := hm.Hero.Level
 		survived, en, xpGained, goldGained, drops := SimulateOneFight(hm.Hero, tickNow, enemy, s.graph, s.combatTickRate, rewardDeps)
-		if s.digestStore != nil {
+		if s.digestStore != nil && OfflineDigestCollecting(hm.Hero.WsDisconnectedAt, tickNow) {
 			if survived {
 				levelGain := hm.Hero.Level - levelBefore
 				_ = s.digestStore.ApplyDelta(ctx, hm.Hero.ID, storage.OfflineDigestDelta{
@@ -206,7 +175,7 @@ func (s *OfflineSimulator) simulateHeroTick(ctx context.Context, hero *model.Her
 					XPGained:       xpGained,
 					GoldGained:     goldGained,
 					LevelsGained:   levelGain,
-					LootAppend:     nonGoldLootForDigest(drops),
+					LootAppend:     NonGoldLootForDigest(drops),
 				})
 			} else {
 				_ = s.digestStore.ApplyDelta(ctx, hm.Hero.ID, storage.OfflineDigestDelta{Deaths: 1})

backend/internal/game/offline_test.go

@@ -7,6 +7,21 @@ import (
 	"github.com/denisovdennis/autohero/internal/model"
 )
 
+func TestOfflineDigestCollecting(t *testing.T) {
+	now := time.Date(2026, 4, 1, 12, 0, 0, 0, time.UTC)
+	recent := now.Add(-20 * time.Second)
+	if OfflineDigestCollecting(&recent, now) {
+		t.Error("expected false before grace window")
+	}
+	old := now.Add(-2 * time.Minute)
+	if !OfflineDigestCollecting(&old, now) {
+		t.Error("expected true after grace window")
+	}
+	if OfflineDigestCollecting(nil, now) {
+		t.Error("expected false when disconnect time is nil")
+	}
+}
+
 func TestSimulateOneFight_HeroSurvives(t *testing.T) {
 	hero := &model.Hero{
 		Level: 1, XP: 0,
@@ -122,14 +137,14 @@ func TestNonGoldLootForDigest(t *testing.T) {
 		{ItemType: "potion", Rarity: model.RarityCommon},
 		{ItemType: "gold", Rarity: model.RarityCommon, GoldAmount: 5},
 	}
-	out := nonGoldLootForDigest(drops)
+	out := NonGoldLootForDigest(drops)
 	if len(out) != 1 || out[0].ItemType != "potion" {
 		t.Fatalf("want single potion line, got %#v", out)
 	}
-	if nonGoldLootForDigest(nil) != nil {
+	if NonGoldLootForDigest(nil) != nil {
 		t.Fatal("nil in -> nil out")
 	}
-	if nonGoldLootForDigest([]model.LootDrop{{ItemType: "gold", GoldAmount: 1}}) != nil {
+	if NonGoldLootForDigest([]model.LootDrop{{ItemType: "gold", GoldAmount: 1}}) != nil {
 		t.Fatal("gold-only -> nil")
 	}
 }

backend/internal/handler/game.go

@@ -193,6 +193,11 @@ func (h *GameHandler) GetHero(w http.ResponseWriter, r *http.Request) {
 			h.logger.Warn("failed to persist buff charges init/rollover", "hero_id", hero.ID, "error", err)
 		}
 	}
+	if h.engine != nil && !h.engine.IsTimePaused() && h.engine.MergeResidentHeroState(hero) {
+		if err := h.store.Save(r.Context(), hero); err != nil {
+			h.logger.Warn("failed to persist engine-merged hero on get", "hero_id", hero.ID, "error", err)
+		}
+	}
 	hero.RefreshDerivedCombatStats(now)
 	writeHeroJSON(w, http.StatusOK, hero)
 }
@@ -757,6 +762,10 @@ func (h *GameHandler) catchUpOfflineGap(ctx context.Context, hero *model.Hero) b
 	if h.engine != nil && h.engine.IsTimePaused() {
 		return false
 	}
+	// Engine already advanced this hero since process start; do not run batch SimulateOneFight (second combat path).
+	if h.engine != nil && h.engine.HeroHasActiveMovement(hero.ID) {
+		return false
+	}
 	gapDuration := h.serverStartedAt.Sub(hero.UpdatedAt)
 	if gapDuration < 30*time.Second {
 		return false
@@ -838,6 +847,13 @@ func (h *GameHandler) InitHero(w http.ResponseWriter, r *http.Request) {
 		}
 	}
 
+	// Resident heroes: single source of truth is the Engine (same ticks as WS observers).
+	if h.engine != nil && !simFrozen && h.engine.MergeResidentHeroState(hero) {
+		if err := h.store.Save(r.Context(), hero); err != nil {
+			h.logger.Warn("failed to persist engine-merged hero on init", "hero_id", hero.ID, "error", err)
+		}
+	}
+
 	// Catch-up simulation: cover the gap between hero.UpdatedAt and serverStartedAt
 	// (the period when the server was down and the offline simulator wasn't running).
 	offlineDuration := time.Since(hero.UpdatedAt)

backend/internal/handler/ws.go

@@ -105,7 +105,7 @@ func (h *Hub) Run() {
 			h.mu.Unlock()
 			h.logger.Info("client disconnected", "hero_id", heroID, "remaining_same_hero", remaining)
 
-			// Always persist; engine drops in-memory movement only when remaining == 0.
+			// Always persist; engine keeps simulating movement/combat without a subscriber.
 			// Synchronous so a reconnect that loads from DB sees the latest save.
 			if existed && h.OnDisconnect != nil {
 				h.OnDisconnect(heroID, remaining)
@@ -135,6 +135,9 @@ func (h *Hub) BroadcastEvent(event model.CombatEvent) {
 
 // SendToHero sends a typed message to all WebSocket connections for a specific hero.
 func (h *Hub) SendToHero(heroID int64, msgType string, payload any) {
+	if !h.IsHeroConnected(heroID) {
+		return
+	}
 	if msgType == "hero_state" {
 		if hero, ok := payload.(*model.Hero); ok {
 			model.AttachDebuffCatalogForClient(hero)

backend/internal/storage/hero_store.go

@@ -713,6 +713,55 @@ func (s *HeroStore) ListOfflineHeroes(ctx context.Context, offlineThreshold time
 	return heroes, nil
 }
 
+// ListHeroesForEngineBootstrap returns heroes that should be loaded into the game engine after a cold start:
+// session ended (ws_disconnected_at set) and simulatable world state. Limit caps memory use.
+func (s *HeroStore) ListHeroesForEngineBootstrap(ctx context.Context, limit int) ([]*model.Hero, error) {
+	if limit <= 0 {
+		limit = 500
+	}
+	if limit > 2000 {
+		limit = 2000
+	}
+
+	query := heroSelectQuery + `
+		WHERE h.hp > 0 AND h.ws_disconnected_at IS NOT NULL
+		AND (
+			(h.state = 'walking'
+				AND (h.move_state IS NULL OR h.move_state NOT IN ('in_town', 'resting')))
+			OR h.state IN ('resting', 'in_town', 'fighting')
+		)
+		ORDER BY h.updated_at ASC
+		LIMIT $1
+	`
+
+	rows, err := s.pool.Query(ctx, query, limit)
+	if err != nil {
+		return nil, fmt.Errorf("list heroes for engine bootstrap: %w", err)
+	}
+	defer rows.Close()
+
+	var heroes []*model.Hero
+	for rows.Next() {
+		h, err := scanHeroFromRows(rows)
+		if err != nil {
+			return nil, fmt.Errorf("list heroes for engine bootstrap scan: %w", err)
+		}
+		heroes = append(heroes, h)
+	}
+	if err := rows.Err(); err != nil {
+		return nil, fmt.Errorf("list heroes for engine bootstrap rows: %w", err)
+	}
+	for _, h := range heroes {
+		if err := s.loadHeroGear(ctx, h); err != nil {
+			return nil, fmt.Errorf("list heroes for engine bootstrap load gear: %w", err)
+		}
+		if err := s.loadHeroInventory(ctx, h); err != nil {
+			return nil, fmt.Errorf("list heroes for engine bootstrap load inventory: %w", err)
+		}
+	}
+	return heroes, nil
+}
+
 // scanHeroFromRows scans the current row from pgx.Rows into a Hero struct.
 // Gear is loaded separately via loadHeroGear after scanning.
 func scanHeroFromRows(rows pgx.Rows) (*model.Hero, error) {