diff --git a/src/game/engine/src/autoloads/turn_manager.gd b/src/game/engine/src/autoloads/turn_manager.gd
index 49e1b4be..f19abc81 100644
--- a/src/game/engine/src/autoloads/turn_manager.gd
+++ b/src/game/engine/src/autoloads/turn_manager.gd
@@ -293,6 +293,14 @@ func next_player() -> void:
 				var fauna_grid: RefCounted = climate_node.get("_grid") as RefCounted
 				if fauna_grid != null:
 					EcologyState.tick(fauna_grid, GameState.map_seed + GameState.turn_number)
+					# Increment 3b: world-event dispatch (geological / biological /
+					# anomalous) against the SAME live grid, after climate + ecology
+					# ticks. Accumulates per-tile eco-damage into WorldsimState's
+					# eco_map (persisted in the save). Production thresholds make
+					# events deliberately rare; this is the missing worldsim layer.
+					WorldsimState.dispatch(
+						fauna_grid, GameState.turn_number, GameState.map_seed
+					)
 		GameState.current_player_index = 0
 		GameState.turn_number += 1
 		# Check victory conditions after all players have moved
diff --git a/src/game/engine/src/autoloads/worldsim_state.gd b/src/game/engine/src/autoloads/worldsim_state.gd
new file mode 100644
index 00000000..03de1979
--- /dev/null
+++ b/src/game/engine/src/autoloads/worldsim_state.gd
@@ -0,0 +1,76 @@
+extends Node
+
+## Session-scoped GdWorldSim singleton (Increment 3b).
+##
+## Owns the continuous-worldsim EVENT layer that runs after the per-turn climate
+## + ecology ticks: geological / biological / anomalous event dispatch, which
+## accumulates per-tile eco-damage into an owned `eco_map`. This is the layer
+## the live `turn_manager.gd::next_player()` was missing — climate and ecology
+## (incl. migration) already tick via ClimatePhysics + EcologyState, but no
+## world events fired in-game.
+##
+## Lifecycle:
+##   _ready()              → reset() builds a fresh GdWorldSim + loads thresholds
+##   dispatch(grid, seed)  → one world-event pass against the LIVE grid
+##                           (read-modify-write; see GdWorldSim::dispatch_on_grid)
+##   to_save_json()/restore_from_save_json() → eco_map save round-trip
+##
+## Thresholds are loaded from the canonical JSON pack (Rail 2) at production
+## rates — events are deliberately rare (~0.003/turn seismic). Proof scenes /
+## tests boost thresholds so events fire reliably in a short run.
+
+const GEO_THRESHOLDS_PATH: String = "res://public/resources/events/geological_thresholds.json"
+const BIO_THRESHOLDS_PATH: String = (
+	"res://public/games/age-of-dwarves/data/balance/biological_events.json"
+)
+
+var worldsim: RefCounted = null
+
+
+func _ready() -> void:
+	reset()
+
+
+## Discard the current GdWorldSim and build a fresh one with production
+## thresholds loaded. Called on new game / load so eco_map does not carry across
+## sessions (the saved eco_map is injected via restore_from_save_json on load).
+func reset() -> void:
+	if not ClassDB.class_exists("GdWorldSim"):
+		worldsim = null
+		return
+	worldsim = ClassDB.instantiate("GdWorldSim") as RefCounted
+	var geo: String = FileAccess.get_file_as_string(GEO_THRESHOLDS_PATH)
+	var bio: String = FileAccess.get_file_as_string(BIO_THRESHOLDS_PATH)
+	# Anomalous has no authored JSON yet — pass "" to keep Rust Default.
+	worldsim.call("load_thresholds_from_json", geo, bio, "")
+
+
+## Run one world-event dispatch pass against the live shared grid. Caller is
+## `turn_manager.gd::next_player()` after the climate + ecology ticks. Returns
+## the number of events dispatched this turn.
+func dispatch(grid: RefCounted, turn: int, seed: int) -> int:
+	if worldsim == null or grid == null:
+		return 0
+	return int(worldsim.call("dispatch_on_grid", grid, turn, seed))
+
+
+## Serialize the eco-damage map for the save envelope. Empty string when no
+## worldsim is active.
+func to_save_json() -> String:
+	if worldsim == null:
+		return ""
+	return String(worldsim.call("eco_map_to_json"))
+
+
+## Restore the eco-damage map from a save envelope payload. No-op on empty input.
+func restore_from_save_json(json: String) -> void:
+	if worldsim == null or json.is_empty():
+		return
+	worldsim.call("restore_eco_map_from_json", json)
+
+
+## Tiles carrying accumulated eco-damage — cheap probe for HUD / tests.
+func eco_damage_tile_count() -> int:
+	if worldsim == null:
+		return 0
+	return int(worldsim.call("eco_map_len"))
diff --git a/src/game/engine/src/autoloads/worldsim_state.gd.uid b/src/game/engine/src/autoloads/worldsim_state.gd.uid
new file mode 100644
index 00000000..df590a7a
--- /dev/null
+++ b/src/game/engine/src/autoloads/worldsim_state.gd.uid
@@ -0,0 +1 @@
+uid://b8d8hc2h052uk