diff --git a/client/scripts/autoloads/game_state.gd b/client/scripts/autoloads/game_state.gd
index 8294f030b..d96294fd2 100644
--- a/client/scripts/autoloads/game_state.gd
+++ b/client/scripts/autoloads/game_state.gd
@@ -1,5 +1,7 @@
 extends Node
 
+signal game_id_changed(new_id: String)
+
 # Updated each frame from ObserverSnapshot data (Protocol format: {tick, entities, tiles}).
 # Entities use Protocol decoded format: {entity_id, x, y, z, kind: {variant, data}}.
 # Tiles use format: [{x, y, z, type}].
@@ -8,7 +10,10 @@ var current_snapshot: Dictionary = {}
 # D-085 (#258): Active game session identifier. Format: <YYYYMMDD>-<HHMMSS>-<hex6>
 # Set by SessionManager.new_game() or SessionManager.resume_game().
 # Empty string when no session is active (main menu state).
-var current_game_id: String = ""
+var current_game_id: String = "":
+	set(v):
+		current_game_id = v
+		game_id_changed.emit(v)
 var current_tick: int = 0
 var player_position: Vector2 = Vector2.ZERO
 var visible_entities: Array = []
diff --git a/client/scripts/autoloads/session_manager.gd b/client/scripts/autoloads/session_manager.gd
index a41c4b554..da1ddade7 100644
--- a/client/scripts/autoloads/session_manager.gd
+++ b/client/scripts/autoloads/session_manager.gd
@@ -22,7 +22,6 @@ func new_game() -> String:
 		now.hour, now.minute, now.second,
 	]
 	var rng := RandomNumberGenerator.new()
-	rng.randomize()
 	var hex_seed := "%06x" % (rng.randi() & 0xFFFFFF)
 	var game_id := "%s-%s" % [timestamp, hex_seed]
 	var save_path := SAVES_DIR + game_id + "/"
@@ -69,16 +68,15 @@ func list_game_dirs() -> Array:
 
 
 ## Show "Save before quitting?" confirmation dialog, then return to main menu.
-## node: the calling scene node (used as dialog parent).
 ## #554: The actual F5 save will be wired here once server supports SaveCommand.
-func quit_to_menu(node: Node) -> void:
+func quit_to_menu() -> void:
 	if _quit_dialog != null and is_instance_valid(_quit_dialog):
 		return  # Dialog already open
 	_quit_dialog = ConfirmationDialog.new()
 	_quit_dialog.dialog_text = UIStrings.get_text("menu.confirm_quit")
 	_quit_dialog.ok_button_text = UIStrings.get_text("menu.confirm_yes")
 	_quit_dialog.cancel_button_text = UIStrings.get_text("menu.confirm_no")
-	node.add_child(_quit_dialog)
+	get_tree().root.add_child(_quit_dialog)
 	_quit_dialog.confirmed.connect(_do_quit_to_menu)
 	_quit_dialog.canceled.connect(_cleanup_quit_dialog)
 	_quit_dialog.popup_centered()
diff --git a/client/scripts/autoloads/sim_bridge.gd b/client/scripts/autoloads/sim_bridge.gd
index f1d4f7fd0..5e7b52283 100644
--- a/client/scripts/autoloads/sim_bridge.gd
+++ b/client/scripts/autoloads/sim_bridge.gd
@@ -72,6 +72,9 @@ var _test_npc_relationship: String:
 	set(v):
 		if harness: harness.npc_relationship = v
 
+var _test_input_queue: Array:
+	get: return harness.input_queue if harness else []
+
 
 # -- Connection lifecycle ------------------------------------------------------
 
diff --git a/client/scripts/ui/debug_overlay.gd b/client/scripts/ui/debug_overlay.gd
index 041f92b0a..362e5758d 100644
--- a/client/scripts/ui/debug_overlay.gd
+++ b/client/scripts/ui/debug_overlay.gd
@@ -77,6 +77,15 @@ func _ready() -> void:
 	_dev_mode = OS.is_debug_build()
 	visible = false
 	_cached_font = ThemeDB.fallback_font
+	# Clear NPC path history on session change to prevent entity ID collisions
+	GameState.connect("game_id_changed", _on_game_id_changed)
+
+
+func _on_game_id_changed(_new_id: String) -> void:
+	_npc_paths.clear()
+	_tick_deltas.clear()
+	_tick_times.clear()
+	_last_tick_processed = -1
 
 
 func _unhandled_input(event: InputEvent) -> void:
diff --git a/client/ui/settings_dialog.gd b/client/ui/settings_dialog.gd
index 55ed74591..cbde721e3 100644
--- a/client/ui/settings_dialog.gd
+++ b/client/ui/settings_dialog.gd
@@ -163,7 +163,7 @@ func _draw() -> void:
 
 func _on_quit_to_menu() -> void:
 	close()
-	SessionManager.quit_to_menu(get_tree().root)
+	SessionManager.quit_to_menu()
 
 
 static func _format_db(db: float) -> String: