Reduce answer review scroll redraws

Reviewed-on: admin/step3#15

scripts/ui/question_player.gd

@@ -60,6 +60,8 @@ var stem_plain_text := ""
 var explanation_plain_text := ""
 var highlight_drag_source := ""
 var timer_color_state := ""
+var last_timer_bar_value := -1.0
+var last_timer_display_seconds := -1
 var pending_correct_advance := false
 var question_text_scale := 1.0
 var presented_choices: Array = []
@@ -1268,6 +1270,8 @@ func _load_question() -> void:
 	flagged = false
 	selected_choice = ""
 	current_answer = {}
+	last_timer_bar_value = -1.0
+	last_timer_display_seconds = -1
 	flag_button.button_pressed = false
 	_refresh_toolbar_state()
 	_clear_answer_review()
@@ -1452,15 +1456,12 @@ func _skip_current_question() -> void:
 		return
 	if BlockSessionService.session_kind != "core":
 		if BlockSessionService.session_kind == "simulation":
+			selected_choice = ""
+			current_answer = {}
 			_save_simulation_current_response()
-		var target_index := _next_revisitable_index()
+		var target_index := _next_pending_simulation_index() if BlockSessionService.session_kind == "simulation" else _next_revisitable_index()
 		if target_index >= 0 and BlockSessionService.move_to(target_index):
 			_load_question()
-		elif BlockSessionService.session_kind == "simulation" and not simulation_submit_pending:
-			simulation_submit_pending = true
-			next_button.disabled = true
-			next_button.text = "Submitting..."
-			ExamSimulationService.submit_block()
 		else:
 			_finish()
 		return
@@ -1492,6 +1493,18 @@ func _next_revisitable_index() -> int:
 	return (BlockSessionService.current_index + 1) % question_count
 
 
+func _next_pending_simulation_index() -> int:
+	var question_count := BlockSessionService.active_questions.size()
+	if question_count == 0:
+		return -1
+	for offset in range(1, question_count + 1):
+		var candidate := (BlockSessionService.current_index + offset) % question_count
+		var answer = BlockSessionService.get_answer_for_index(candidate)
+		if answer == null or str(answer.get("selected_choice_id", "")) == "":
+			return candidate
+	return -1
+
+
 func _choice_gui_input(event: InputEvent, index: int) -> void:
 	if pending_correct_advance or followup_required or _is_correct_answer_locked():
 		return
@@ -1539,12 +1552,15 @@ func _toggle_eliminate_selected() -> void:
 
 func _submit_or_next() -> void:
 	if BlockSessionService.session_kind == "simulation":
+		if selected_choice == "":
+			return
 		_save_simulation_current_response()
-		if BlockSessionService.current_index + 1 < BlockSessionService.active_questions.size():
+		var pending_index := _next_pending_simulation_index()
-			BlockSessionService.move_next()
+		if pending_index >= 0:
+			BlockSessionService.move_to(pending_index)
 			_load_question()
 			return
-		elif not simulation_submit_pending:
+		if not simulation_submit_pending:
 			simulation_submit_pending = true
 			next_button.disabled = true
 			next_button.text = "Submitting..."
@@ -1706,6 +1722,9 @@ func _on_random_question_failed(message: String) -> void:
 
 
 func _show_answer_review() -> void:
+	if BlockSessionService.session_kind == "simulation":
+		_clear_answer_review()
+		return
 	_show_explanation()
 	_show_references(BlockSessionService.get_current_question().get("references", []))
 	_ensure_answer_review_followups()
@@ -1844,6 +1863,9 @@ func _render_review_followups() -> void:
 	if review_followups_content == null:
 		return
 	_clear_container_children(review_followups_content)
+	if BlockSessionService.session_kind == "simulation":
+		review_followups_section.visible = false
+		return
 	if not BlockSessionService.show_review_followups:
 		review_followups_section.visible = false
 		return
@@ -2076,7 +2098,10 @@ func _update_timer_bar() -> void:
 		return
 	var is_core_timer := BlockSessionService.session_kind == "core"
 	var ratio := BlockSessionService.get_session_timer_ratio()
-	timer_bar.value = ratio * 100.0
+	var next_value := ratio * 100.0
+	if last_timer_bar_value < 0.0 or absf(next_value - last_timer_bar_value) >= 0.1:
+		last_timer_bar_value = next_value
+		timer_bar.value = next_value
 	if is_core_timer and timer_label.visible:
 		_set_timer_display(int(floor(BlockSessionService.get_core_question_total_elapsed_seconds())))
 	var color_state := "blue"
@@ -2096,6 +2121,9 @@ func _set_timer_display(total_seconds: int) -> void:
 	if timer_label == null:
 		return
 	var safe_seconds := maxi(0, total_seconds)
+	if safe_seconds == last_timer_display_seconds:
+		return
+	last_timer_display_seconds = safe_seconds
 	timer_label.text = "%02d:%02d" % [int(floor(float(safe_seconds) / 60.0)), safe_seconds % 60]
 
 
@@ -3327,7 +3355,8 @@ func _refresh_submit_state() -> void:
 	if next_button == null:
 		return
 	if BlockSessionService.session_kind == "simulation":
-		next_button.disabled = false
+		next_button.disabled = selected_choice == ""
+		next_button.text = "Submit Block" if selected_choice != "" and _next_pending_simulation_index() < 0 else "Next"
 		return
 	if pending_correct_advance or followup_required:
 		next_button.disabled = true

tests/post_answer_review_test.gd

@@ -22,6 +22,7 @@ func _initialize() -> void:
 	_test_feedback_context_excludes_study_content()
 	_test_feedback_form_validation()
 	_test_revisitable_navigation_prefers_unanswered_questions()
+	_test_timer_text_avoids_redundant_frame_updates()
 	_test_submit_styles_keep_stable_geometry()
 	_test_core_timer_counts_up_and_remains_visible()
 	await _test_player_runtime_construction()
@@ -341,12 +342,34 @@ func _test_revisitable_navigation_prefers_unanswered_questions() -> void:
 	session.answers[1] = {"selected_choice_id": "B"}
 	session.current_index = 2
 	_assert(player._next_revisitable_index() == 0, "skip should wrap rather than reload the same unanswered question")
+	session.answers = [{"selected_choice_id": "A"}, null, {"selected_choice_id": "C"}]
+	session.current_index = 2
+	_assert(player._next_pending_simulation_index() == 1, "simulation should cycle an earlier skipped question back")
+	session.answers[1] = {"selected_choice_id": "B"}
+	_assert(player._next_pending_simulation_index() == -1, "simulation should submit only after every question has an answer")
+	session.answers[2] = {"selected_choice_id": ""}
+	session.current_index = 2
+	_assert(player._next_pending_simulation_index() == 2, "the only skipped simulation question should remain pending")
 	player.free()
 	session.active_questions = prior_questions
 	session.answers = prior_answers
 	session.current_index = prior_index
 
 
+func _test_timer_text_avoids_redundant_frame_updates() -> void:
+	var player = load("res://scripts/ui/question_player.gd").new()
+	player.timer_label = Label.new()
+	player._set_timer_display(65)
+	_assert(player.timer_label.text == "01:05", "timer should render a changed second")
+	player.timer_label.text = "unchanged"
+	player._set_timer_display(65)
+	_assert(player.timer_label.text == "unchanged", "timer should not rewrite its label every frame")
+	player._set_timer_display(66)
+	_assert(player.timer_label.text == "01:06", "timer should render the next changed second")
+	player.timer_label.free()
+	player.free()
+
+
 func _test_player_runtime_construction() -> void:
 	var host := Control.new()
 	root.add_child(host)