diff --git a/autoload/global.gd b/autoload/global.gd
index 7ce7a15..5746961 100644
--- a/autoload/global.gd
+++ b/autoload/global.gd
@@ -59,8 +59,23 @@ func get_description(item_id: String, items: Array = []) -> String:
 
 func format_number(value: float, digits: int = 0) -> String:
     if value == 0: return ""
-    if value < 10_000:
-        return "%.*f" % [digits, value]
+    # Keep ordinary quantities readable, grouping thousands with spaces.
+    # Scientific notation is reserved for values whose fixed form would be
+    # unwieldy in the UI.
+    if absf(value) < 1_000_000_000.0:
+        var fixed: String = "%.*f" % [digits, value]
+        var parts: PackedStringArray = fixed.split(".", true)
+        var integer: String = parts[0]
+        var sign: String = ""
+        if integer.begins_with("-") or integer.begins_with("+"):
+            sign = integer.left(1)
+            integer = integer.substr(1)
+        var grouped: String = ""
+        while integer.length() > 3:
+            grouped = " " + integer.right(3) + grouped
+            integer = integer.left(integer.length() - 3)
+        grouped = sign + integer + grouped
+        return grouped + ("." + parts[1] if parts.size() > 1 else "")
 
     var exp_value = int(floor(log(abs(value)) / log(10.0)))
     var mantissa = value / pow(10.0, exp_value)
diff --git a/autoload/save_manager.gd b/autoload/save_manager.gd
index 5cd1666..ba5b0f7 100644
--- a/autoload/save_manager.gd
+++ b/autoload/save_manager.gd
@@ -5,7 +5,7 @@ extends Node
 const SETTING_SECTION := "Settings"
 const SAVE_PATH = "user://settings.cfg"
 
-const FORMAT_VERSION: int = 1
+const FORMAT_VERSION: int = 2
 const SimulationTime = preload("res://world/owniverse/simulation_time.gd")
 const STATE_VERSION: String = SimulationTime.STATE_VERSION
 var last_error: String = ""
@@ -113,44 +113,44 @@ func _plain_tree(value: Variant) -> bool:
 
 ## Return a diagnostic path on failure; an empty string means the structure is valid.
 func validate_data(data: Variant) -> String:
-    if not data is Dictionary or not data.get("state") is Dictionary:
+    if not data is Dictionary or not _plain_tree(data):
+        return "save must contain plain finite values"
+    if data.get("format_version") != FORMAT_VERSION or not data.get("app_version") is String:
+        return "unsupported save format"
+    if not data.get("ui") is Dictionary or not data.ui.get("current_page") is int or data.ui.current_page < 0:
+        return "invalid ui.current_page"
+    if not data.get("state") is Dictionary:
         return "state must be a Dictionary"
-    if not _plain_tree(data):
-        return "unsupported value or non-finite number"
-    # Legacy files contained only {state}; accept their known state schema.
-    if data.has("format_version") and (not data.format_version is int or data.format_version != FORMAT_VERSION):
-        return "unsupported format_version"
-    if data.has("ui"):
-        if not data.ui is Dictionary or not data.ui.get("current_page") is int or data.ui.current_page < 0:
-            return "invalid ui.current_page"
     var saved: Dictionary = data.state
-    if saved.get("version") not in [STATE_VERSION, SimulationTime.LEGACY_VERSION]:
+    var required := [
+        "version", "time", "speed", "speed_in_year", "energy", "batches", "batch_origins",
+        "binds", "amount", "distribution", "auto_resources", "auto_star_deficits",
+        "production_remainders", "resource_remainders", "evolution_remainders", "life_remainders",
+        "planet_remainders", "blast_remainders", "destruction_remainders", "civilization_remainders",
+        "civilization_stats", "civilization_homes", "ethics", "stats",
+    ]
+    if saved.size() != required.size():
+        return "unsupported state structure"
+    for field in required:
+        if not saved.has(field):
+            return "missing state." + field
+    if saved.version != STATE_VERSION:
         return "unsupported state.version"
-    if not saved.get("time") is Dictionary:
-        return "state.time must be a Dictionary"
-    if not _number(saved.time.get("datetime")) or not _number(saved.time.get("year")):
+    if not saved.time is Dictionary or not _number(saved.time.get("datetime")) or not _number(saved.time.get("year")):
         return "invalid state.time"
-    if not is_finite(float(saved.time.datetime) * 10.0):
-        return "state.time exceeds supported precision range"
-    var expected_year: float = SimulationTime.processed_year(saved.time.datetime)
-    if saved.version == SimulationTime.LEGACY_VERSION:
-        expected_year = floorf(saved.time.datetime)
-    if saved.time.year != expected_year:
-        return "state.time.year does not match the processed time for this version"
-    if not _number(saved.get("speed"), true) or saved.speed < 1 or saved.speed > Global.SPEED_LIMIT:
+    if not is_finite(float(saved.time.datetime) * 10.0) or saved.time.year != SimulationTime.processed_year(saved.time.datetime):
+        return "invalid processed time"
+    if not _number(saved.speed, true) or saved.speed < 1 or saved.speed > Global.SPEED_LIMIT:
         return "invalid state.speed"
-    if not _number(saved.get("speed_in_year")) or saved.speed_in_year != pow(10.0, saved.speed - 1):
+    if not _number(saved.speed_in_year) or saved.speed_in_year != pow(10.0, saved.speed - 1):
         return "invalid state.speed_in_year"
-    if not _number(saved.get("energy"), true):
-        return "invalid state.energy"
-    if not _number_map(saved.get("amount"), true):
-        return "invalid state.amount"
-    if not saved.get("stats") is Dictionary or not _number_map(saved.stats.get("total_amount"), true):
+    if not _number(saved.energy, true) or not _number_map(saved.amount, true):
+        return "invalid state resources"
+    if not saved.stats is Dictionary or not _number_map(saved.stats.get("total_amount"), true):
         return "invalid state.stats.total_amount"
-    for id in saved.amount:
-        if not saved.stats.total_amount.has(id):
-            return "missing total_amount for " + id
-    if not saved.get("binds") is Dictionary or not saved.get("batches") is Dictionary:
+    if saved.amount.keys() != saved.stats.total_amount.keys():
+        return "amount and total_amount keys differ"
+    if not saved.binds is Dictionary or not saved.batches is Dictionary:
         return "state.binds and state.batches must be Dictionaries"
     for owner_id in saved.binds:
         if not saved.amount.has(owner_id) or not _number_map(saved.binds[owner_id], true):
@@ -162,57 +162,42 @@ func validate_data(data: Variant) -> String:
         if not saved.amount.has(id) or not saved.batches[id] is Array:
             return "invalid state.batches." + id
         for batch in saved.batches[id]:
-            if not batch is Dictionary:
-                return "batch must be a Dictionary"
-            if not _number(batch.get("amount"), true) or not _number(batch.get("start_year")) or not _number(batch.get("end_year")):
+            if not batch is Dictionary or not _number(batch.get("amount"), true) or not _number(batch.get("start_year")) or not _number(batch.get("end_year")):
                 return "invalid batch in " + id
             if batch.end_year < batch.start_year:
                 return "reversed batch interval in " + id
-            if batch.has("created_from") or batch.has("created_to"):
-                if not _number(batch.get("created_from")) or not _number(batch.get("created_to")):
-                    return "invalid batch creation interval in " + id
-                if batch.created_to <= batch.created_from or batch.start_year < batch.created_from:
-                    return "reversed batch creation interval in " + id
-            if batch.has("processed_until"):
-                if not _number(batch.processed_until) or batch.processed_until < batch.start_year or batch.processed_until > batch.end_year:
-                    return "invalid batch.processed_until in " + id
+            if batch.has("created_from") != batch.has("created_to"):
+                return "incomplete batch creation interval in " + id
+            if batch.has("created_from") and (not _number(batch.created_from) or not _number(batch.created_to) or batch.created_to <= batch.created_from or batch.start_year < batch.created_from):
+                return "invalid batch creation interval in " + id
+            if batch.has("processed_until") and (not _number(batch.processed_until) or batch.processed_until < batch.start_year or batch.processed_until > batch.end_year):
+                return "invalid batch.processed_until in " + id
             if batch.has("withdraw_remainder") and (not _number(batch.withdraw_remainder) or batch.withdraw_remainder > batch.amount):
                 return "invalid batch.withdraw_remainder in " + id
-    for field in ["batch_origins", "distribution", "auto_resources", "production_remainders", "auto_star_deficits", "evolution_remainders", "planet_remainders", "blast_remainders", "destruction_remainders"]:
-        if saved.has(field) and not _number_map(saved[field], field == "auto_resources", field != "auto_star_deficits"):
+    for field in ["batch_origins", "distribution", "production_remainders", "evolution_remainders", "planet_remainders", "blast_remainders", "destruction_remainders", "life_remainders", "civilization_remainders", "civilization_stats"]:
+        if not _number_map(saved[field], false, false):
             return "invalid state." + field
-    if saved.has("ethics"):
-        if not saved.ethics is Dictionary:
-            return "invalid state.ethics"
-        for id in saved.ethics:
-            if not Global.CivilizationRules.has(id) or not _number_map(saved.ethics[id], true):
-                return "invalid state.ethics." + str(id)
-            for ethic in saved.ethics[id]:
-                if ethic not in ["m", "l", "w", "d", "c", "b"]:
-                    return "invalid ethic " + str(ethic)
-    if saved.has("life_version") and saved.life_version not in [1, 2, 3]:
-        return "invalid state.life_version"
-    if saved.has("civilization_remainders") and not _number_map(saved.civilization_remainders, false, false):
-        return "invalid state.civilization_remainders"
-    if saved.has("civilization_stats") and not _number_map(saved.civilization_stats):
-        return "invalid state.civilization_stats"
-    if saved.has("civilization_homes"):
-        if not saved.civilization_homes is Dictionary:
-            return "invalid state.civilization_homes"
-        for id in saved.civilization_homes:
-            if not _number_map(saved.civilization_homes[id], true):
-                return "invalid civilization homes"
-    if saved.has("life_remainders") and not _number_map(saved.life_remainders, false, false):
-        return "invalid state.life_remainders"
-    if saved.has("resource_remainders"):
-        if not saved.resource_remainders is Dictionary:
-            return "invalid state.resource_remainders"
-        for channel in ["basic", "automatic"]:
-            # Signed allocation errors are valid, even though resource balances are whole.
-            if not _number_map(saved.resource_remainders.get(channel), false, false):
-                return "invalid state.resource_remainders." + channel
+    if not _number_map(saved.auto_resources, true) or not _number_map(saved.auto_star_deficits, false, false):
+        return "invalid automatic production state"
+    if not saved.resource_remainders is Dictionary or saved.resource_remainders.keys().size() != 2 or not saved.resource_remainders.has("basic") or not saved.resource_remainders.has("automatic"):
+        return "invalid state.resource_remainders"
+    for channel in ["basic", "automatic"]:
+        if not _number_map(saved.resource_remainders[channel], false, false):
+            return "invalid state.resource_remainders." + channel
+    if not saved.ethics is Dictionary or not saved.civilization_homes is Dictionary:
+        return "invalid civilization state"
+    for id in saved.ethics:
+        if not Global.CivilizationRules.has(id) or not _number_map(saved.ethics[id], true):
+            return "invalid state.ethics." + str(id)
+        for ethic in saved.ethics[id]:
+            if ethic not in ["m", "l", "w", "d", "c", "b"]:
+                return "invalid ethic " + str(ethic)
+    for id in saved.civilization_homes:
+        if not _number_map(saved.civilization_homes[id], true):
+            return "invalid civilization homes"
     return ""
 
+
 #endregion
 
 
diff --git a/stage/stage.gd b/stage/stage.gd
index a504eef..803e294 100644
--- a/stage/stage.gd
+++ b/stage/stage.gd
@@ -86,7 +86,10 @@ var locked_items: Array = []
 
 
 func set_datetime(value: float):
-    date_time.text = Global.format_number(value, 5) if value != 0.0 else "0.0"
+    # Simulation time advances in tenths of a year; displaying five decimal
+    # places only adds zeroes and suggests precision the simulation does not
+    # have.
+    date_time.text = Global.format_number(value, 1) if value != 0.0 else "0.0"
 
 #region Item manipulations: update and visibility
 
@@ -403,12 +406,9 @@ func load_data() -> bool:
             SaveManager.blocked_saves["owniverse"] = true
             push_error("Save is missing the current entity: " + id)
             return false
-    var complete: Dictionary = owniverse.state.duplicate(true)
-    complete.merge(restored, true)
-    owniverse.state = complete
-    owniverse.new_state = complete
+    owniverse.state = restored
+    owniverse.new_state = restored.duplicate(true)
     owniverse.initialize_life_batches()
-    owniverse.migrate_time_precision()
     owniverse.refresh_item_amounts()
     pending_page = clampi(int(game_data.get("ui", {}).get("current_page", 0)), 0, PAGE_COUNT - 1)
     _restore_page.call_deferred()
diff --git a/tests/README.md b/tests/README.md
index af7192c..4fe941d 100644
--- a/tests/README.md
+++ b/tests/README.md
@@ -8,14 +8,14 @@ godot --headless --path Owniverse.GI --script res://tests/test_time.gd
 
 Команда выполняется из общей папки проектов. Тесты используют искусственные состояния; сохранение игрока не читается и не перезаписывается.
 
-Проверяются границы десятых долей года, производство ресурсов на этих границах, накопление дробного остатка, скорости 1–10 000 лет/сек, продолжение после загрузки, недопустимые интервалы и миграция сохранений.
+Проверяются границы десятых долей года, производство ресурсов на этих границах, накопление дробного остатка, скорости 1–10 000 лет/сек, продолжение после загрузки и недопустимые интервалы.
 
 Схема состояния `0.1.1` хранит:
 
 - `time.datetime` — накопленный возраст, включая необработанную дробную часть;
 - `time.year` — последний рассчитанный возраст с точностью до десятой доли года.
 
-Сохранения `0.1.0` проходят старую проверку целого года. При загрузке стадией игры оставшийся промежуток до последней десятой рассчитывается ровно один раз, после чего применяется версия `0.1.1`. Оставшаяся часть меньше 0,1 года сохраняется.
+Сохранения используют только актуальную структуру состояния и не поддерживают прежние форматы.
 
 ## Согласованные правила эволюции
 
@@ -55,7 +55,7 @@ godot --headless --path Owniverse.GI --script res://tests/test_life.gd
 
 Проверяются абиогенез, деградация, повторные попытки без создания дополнительных планет, появление C0.0 на прежней звезде, остатки вероятностей, сохранение/продолжение, однократная инициализация старых планет и отсутствие воскрешения после бластов.
 
-Проверка загрузки этических правил, миграции распределений и отделения космических цивилизаций:
+Проверка загрузки этических правил, распределений и отделения космических цивилизаций:
 
 ```sh
 godot --headless --path Owniverse.GI --script res://tests/test_civilization_state.gd
@@ -70,4 +70,4 @@ godot --headless --path Owniverse.GI --script res://tests/test_civilization_stat
 godot --headless --path Owniverse.GI --script res://tests/test_civilization_evolution.gd
 ```
 
-Проверяются реальные коэффициенты C0.2, войны и побочный ущерб C2.0, замена планет колониями с сохранением хозяина, дипломатическое влияние, бонус периода от структур и деградация при их отсутствии. Ускоренная модель проходит все стадии C0.2 → C4.4 → Ct. Проверки контролируют сохранение населения, целочисленность этик, валидацию сохранения и детерминированное продолжение после сериализации. Миграция часов цивилизаций использует `life_version = 3`.
+Проверяются реальные коэффициенты C0.2, войны и побочный ущерб C2.0, замена планет колониями с сохранением хозяина, дипломатическое влияние, бонус периода от структур и деградация при их отсутствии. Ускоренная модель проходит все стадии C0.2 → C4.4 → Ct. Проверки контролируют сохранение населения, целочисленность этик, валидацию сохранения и детерминированное продолжение после сериализации.
diff --git a/tests/test_civilization_evolution.gd b/tests/test_civilization_evolution.gd
index f96ea5b..2819149 100644
--- a/tests/test_civilization_evolution.gd
+++ b/tests/test_civilization_evolution.gd
@@ -52,7 +52,7 @@ func invariants(world) -> void:
         check(sum_ethics(world, id) == physical.get(id, 0.0), "Ethics equal physical population for " + id)
         for n in world.state.ethics[id].values():
             if n < 0.0 or n != floorf(n): check(false, "Invalid ethic amount")
-    check(root.get_node("SaveManager").validate_data({"state": world.state}) == "", "Civilization state validates")
+    check(root.get_node("SaveManager").validate_data({"format_version": 2, "app_version": "", "ui": {"current_page": 0}, "state": world.state}) == "", "Civilization state validates")
 
 func run() -> void:
     var global: Node = root.get_node("Global")
diff --git a/tests/test_civilization_state.gd b/tests/test_civilization_state.gd
index 4099645..a37654c 100644
--- a/tests/test_civilization_state.gd
+++ b/tests/test_civilization_state.gd
@@ -58,7 +58,7 @@ func run() -> void:
     world.state.amount["C0.2"] = 3.0
     world.initialize_life_batches()
     check(world.state.ethics["C0.2"].m == 3.0, "Losses reduce ethics without inventing population")
-    check(root.get_node("SaveManager").validate_data({"state": world.state}) == "", "Ethics state validates")
+    check(root.get_node("SaveManager").validate_data({"format_version": 2, "app_version": "", "ui": {"current_page": 0}, "state": world.state}) == "", "Ethics state validates")
     var restored = fixture()
     restored.state = bytes_to_var(var_to_bytes(world.state))
     restored.initialize_life_batches()
@@ -116,7 +116,7 @@ func run() -> void:
     world.initialize_life_batches()
     check(world.state.amount["C4.2"] == 2.0, "SMBH capacity uses stellar mass equivalent")
     check(world._physical_amounts(world.state)["C1.9"] == 1.0, "Unsupported civilization degrades through missing habitat families")
-    check(root.get_node("SaveManager").validate_data({"state": world.state}) == "", "Capacity-limited state validates")
+    check(root.get_node("SaveManager").validate_data({"format_version": 2, "app_version": "", "ui": {"current_page": 0}, "state": world.state}) == "", "Capacity-limited state validates")
     dispose(world)
 
     world = fixture()
diff --git a/tests/test_group_index.gd b/tests/test_group_index.gd
new file mode 100644
index 0000000..deab3f1
--- /dev/null
+++ b/tests/test_group_index.gd
@@ -0,0 +1,58 @@
+extends SceneTree
+const Clock = preload("res://world/owniverse/simulation_time.gd")
+var checks: int = 0
+var failures: int = 0
+
+func _initialize() -> void:
+    call_deferred("run")
+
+func check(condition: bool, message: String) -> void:
+    checks += 1
+    if not condition:
+        failures += 1
+        push_error(message)
+
+func fixture():
+    var world = load("res://world/owniverse/owniverse.gd").new()
+    var global: Node = root.get_node("Global")
+    for id in global.OwniverseEntities:
+        var entity = load("res://world/owniverse/owniverse_entity.gd").new(global.OwniverseEntities[id])
+        world.entities[id] = entity
+        world.state.amount[id] = 0.0
+        world.state.stats.total_amount[id] = 0.0
+        if entity.group_as != "":
+            world.state.amount[entity.group_as] = 0.0
+            world.state.stats.total_amount[entity.group_as] = 0.0
+    world.entities["N"].life_product = {}
+    world.entities["N"].product_per_year_type = "H"
+    world.entities["N"].product_per_year_amount = 10.0
+    world.entities["N"].auto = 0.0
+    world.state.amount.N = 1.0
+    return world
+
+func dispose(world) -> void:
+    for entity in world.entities.values():
+        entity.free()
+    world.free()
+
+func run() -> void:
+    var world = fixture()
+    for id in world.entities:
+        var expected: Array = []
+        for key in world.entities:
+            if world.entities[key].group_as == id:
+                expected.append(key)
+        check(world._is_group(id) == (not expected.is_empty()), "Group classification: " + id)
+        check(world._members(id) == (expected if not expected.is_empty() else [id]), "Group members: " + id)
+    var members: Array = world._members("Star")
+    members.clear()
+    check(not world._members("Star").is_empty(), "Returned members are independent")
+    world.entities.N.group_as = "TestGroup"
+    world.rebuild_group_index()
+    check(world._members("TestGroup") == ["N"], "Explicit definition reload")
+    world.entities.N.free()
+    world.entities.erase("N")
+    check(not world._is_group("TestGroup"), "Removed definition invalidates index")
+    print("Group index: %d checks, %d failures" % [checks, failures])
+    dispose(world)
+    quit(1 if failures else 0)
diff --git a/tests/test_group_index.gd.uid b/tests/test_group_index.gd.uid
new file mode 100644
index 0000000..e40e3eb
--- /dev/null
+++ b/tests/test_group_index.gd.uid
@@ -0,0 +1 @@
+uid://bykrkembtacbw
diff --git a/tests/test_life.gd b/tests/test_life.gd
index d56cd5a..cb5d057 100644
--- a/tests/test_life.gd
+++ b/tests/test_life.gd
@@ -53,7 +53,7 @@ func run() -> void:
     check(world.state.batches.HP.size() > 0, "Survivors get next attempt")
     var physical: Dictionary = world._physical_amounts(world.state)
     check(physical.HP + physical.EON1 + physical.RP == 40000.0, "Life conserves planets")
-    check(root.get_node("SaveManager").validate_data({"state": world.state}) == "", "Life save validates")
+    check(root.get_node("SaveManager").validate_data({"format_version": 2, "app_version": "", "ui": {"current_page": 0}, "state": world.state}) == "", "Life save validates")
     var restored = fixture()
     restored.state = bytes_to_var(var_to_bytes(world.state))
     world._evolve_batches(world.state, 11e6)
@@ -100,13 +100,12 @@ func run() -> void:
     dispose(world)
     world = fixture()
     world.state.time = {"datetime": 123.4, "year": 123.4}
-    world.state.life_version = 1
     world.state.amount["C0.0"] = 40000.0
     world.initialize_life_batches()
-    check(world.state.life_version == 3 and world.state.batches["C0.0"][0].created_from == 123.4, "Previous life saves receive missing civilization cohorts")
+    check(world.state.batches["C0.0"][0].created_from == 123.4, "Civilization cohorts begin at the current time")
     before = world.state.duplicate(true)
     world.initialize_life_batches()
-    check(world.state == before, "Second life migration is idempotent")
+    check(world.state == before, "Life batch initialization is idempotent")
     world._evolve_batches(world.state, 2173.4)
     check(world.state.amount["C0.1"] == 700.0 and world.state.amount.EON5 == 1000.0, "C0.0 progresses and degrades by Unity rates")
     check(world.state.amount["C0.0"] == 38300.0, "C0.0 remainder stays alive")
@@ -118,7 +117,7 @@ func run() -> void:
     world._evolve_batches(world.state, 2050.0)
     check(world.state.binds.RD["C0.2"] == 700.0, "C0.1 reaches ethical civilization without losing host")
     check(world.state.binds.RD["C0.0"] == 1000.0, "C0.1 degradation follows Unity")
-    check(root.get_node("SaveManager").validate_data({"state": world.state}) == "", "Extended life save validates")
+    check(root.get_node("SaveManager").validate_data({"format_version": 2, "app_version": "", "ui": {"current_page": 0}, "state": world.state}) == "", "Extended life save validates")
     dispose(world)
     print("Life: %d checks, %d failures" % [checks, failures])
     quit(0 if failures == 0 else 1)
diff --git a/tests/test_production_transaction.gd b/tests/test_production_transaction.gd
new file mode 100644
index 0000000..ae1576a
--- /dev/null
+++ b/tests/test_production_transaction.gd
@@ -0,0 +1,58 @@
+extends SceneTree
+const Clock = preload("res://world/owniverse/simulation_time.gd")
+var checks: int = 0
+var failures: int = 0
+
+func _initialize() -> void:
+    call_deferred("run")
+
+func check(condition: bool, message: String) -> void:
+    checks += 1
+    if not condition:
+        failures += 1
+        push_error(message)
+
+func fixture():
+    var world = load("res://world/owniverse/owniverse.gd").new()
+    var global: Node = root.get_node("Global")
+    for id in global.OwniverseEntities:
+        var entity = load("res://world/owniverse/owniverse_entity.gd").new(global.OwniverseEntities[id])
+        world.entities[id] = entity
+        world.state.amount[id] = 0.0
+        world.state.stats.total_amount[id] = 0.0
+        if entity.group_as != "":
+            world.state.amount[entity.group_as] = 0.0
+            world.state.stats.total_amount[entity.group_as] = 0.0
+    world.entities["N"].life_product = {}
+    world.entities["N"].product_per_year_type = "H"
+    world.entities["N"].product_per_year_amount = 10.0
+    world.entities["N"].auto = 0.0
+    world.state.amount.N = 1.0
+    return world
+
+func dispose(world) -> void:
+    for entity in world.entities.values():
+        entity.free()
+    world.free()
+
+func run() -> void:
+    var world = fixture()
+    world.initialize_life_batches()
+    world.entities.N.cost = {"H": 2.0}
+    world.entities.N.bind = {"S": 3.0}
+    world.state.amount.H = 10.0
+    world.state.amount.S = 0.0
+    world.state.auto_resources = {"H": 10.0}
+    world.state.batches.H = [{"amount": 10.0, "start_year": 1.0, "end_year": 2.0}]
+    var before: Dictionary = world.state.duplicate(true)
+    check(not world._try_production(world.state, world.entities.N, 1.0, true), "Binding failure rejects production")
+    check(world.state == before, "Failure preserves costs, batches and budget")
+    world.state.amount.S = 10.0
+    var old_batches: Array = world.state.batches.H
+    check(world._try_production(world.state, world.entities.N, 2.0, true), "Funded production succeeds")
+    check(world.state.amount.H == 6.0 and world.state.amount.S == 4.0, "Exact cost and binding")
+    check(world.state.auto_resources.H == 6.0, "Exact automatic budget")
+    check(old_batches[0].amount == 10.0 and world.state.batches.H[0].amount == 6.0, "Consumed batches isolated")
+    print("Transaction: %d checks, %d failures" % [checks, failures])
+    dispose(world)
+    quit(1 if failures else 0)
diff --git a/tests/test_production_transaction.gd.uid b/tests/test_production_transaction.gd.uid
new file mode 100644
index 0000000..013d4ce
--- /dev/null
+++ b/tests/test_production_transaction.gd.uid
@@ -0,0 +1 @@
+uid://byjixspismsnh
diff --git a/tests/test_stellar_rules.gd b/tests/test_stellar_rules.gd
index 76e9011..7b9f875 100644
--- a/tests/test_stellar_rules.gd
+++ b/tests/test_stellar_rules.gd
@@ -84,7 +84,7 @@ func run() -> void:
     check(world.state.binds.RD.GG == 16.0 and world.state.binds.RD.AB == 120.0, "Planet multiplicity applied")
     check(world.state.amount.HP == 0.0 and world.state.stats.total_amount.HP == 1.0, "Created planets are bound, counted once")
     var saves: Node = root.get_node("SaveManager")
-    check(saves.validate_data({"state": world.state}) == "", "Planet carry save validates")
+    check(saves.validate_data({"format_version": 2, "app_version": "", "ui": {"current_page": 0}, "state": world.state}) == "", "Planet carry save validates")
     restored = fixture()
     restored.state = bytes_to_var(var_to_bytes(world.state))
     world._create_planets(world.state, "RD", 37.0, 0.0, 0.0, 0.7)
@@ -106,7 +106,7 @@ func run() -> void:
     check(world.state.amount.RP == 0.0 and world.state.amount["C1.3"] == 0.0, "Inherited planets never become free")
     world._evolve_batches(world.state, lifespan + width)
     check(world.state.binds.RD["C1.3"] == 0.0 and world.state.binds.TWD["C1.3"] == 4.0, "No planets left at extinct parent type")
-    check(saves.validate_data({"state": world.state}) == "", "Inherited state validates")
+    check(saves.validate_data({"format_version": 2, "app_version": "", "ui": {"current_page": 0}, "state": world.state}) == "", "Inherited state validates")
     dispose(world)
 
     world = fixture()
@@ -146,7 +146,7 @@ func run() -> void:
     check(world.state.amount.SN == 0.0 and world.state.amount.LNS == 1.0, "Supernova produces a remnant")
     check(world.state.amount.H == 8.0 and world.state.amount.He == 50.0 and world.state.amount.Met == 11.0, "Supernova returns table resources")
     check(not world.state.amount.has("blast"), "Supernova dispatches blast output")
-    check(saves.validate_data({"state": world.state}) == "", "Blast state validates")
+    check(saves.validate_data({"format_version": 2, "app_version": "", "ui": {"current_page": 0}, "state": world.state}) == "", "Blast state validates")
     dispose(world)
 
     world = fixture()
diff --git a/tests/test_time.gd b/tests/test_time.gd
index b958f81..36e40cc 100644
--- a/tests/test_time.gd
+++ b/tests/test_time.gd
@@ -50,10 +50,10 @@ func run() -> void:
     for invalid in [0.0, -1.0, NAN, INF, 1e308]:
         world.evolute(invalid)
         check(world.state == before, "Invalid/overflow interval rejected")
-    check(saves.validate_data({"state": world.state}) == "", "Fractional save is valid")
+    check(saves.validate_data({"format_version": 2, "app_version": "", "ui": {"current_page": 0}, "state": world.state}) == "", "Fractional save is valid")
     var invalid_save: Dictionary = world.state.duplicate(true)
     invalid_save.time.year = 0.25
-    check(saves.validate_data({"state": invalid_save}) != "", "Reject inconsistent fractional clock")
+    check(saves.validate_data({"format_version": 2, "app_version": "", "ui": {"current_page": 0}, "state": invalid_save}) != "", "Reject inconsistent fractional clock")
     dispose(world)
 
     for fps in [30, 60, 144]:
@@ -76,26 +76,7 @@ func run() -> void:
     dispose(world)
 
     world = fixture()
-    world.state.version = "0.1.0"
-    world.state.time = {"datetime": 0.45, "year": 0.0}
-    check(saves.validate_data({"state": world.state}) == "", "Accept legacy integer-year save")
-    world.migrate_time_precision()
-    check(world.state.version == "0.1.1", "Migrate schema version")
-    check(world.state.time.year == 0.4 and world.state.time.datetime == 0.45, "Keep unprocessed sub-tenth remainder")
-    check(world.state.amount.H == 4.0, "Migration processes pending legacy time")
-    check(saves.validate_data({"state": world.state}) == "", "Migrated state validates")
-    before = world.state.duplicate(true)
-    world.migrate_time_precision()
-    check(world.state == before, "Migration is idempotent")
-    # Verify in-memory save roundtrip without touching the player's save.
-    var restored = fixture()
-    restored.state = bytes_to_var(var_to_bytes(world.state))
-    world.evolute(0.05)
-    restored.evolute(0.05)
-    check(world.state == restored.state, "Save continuation preserves time and production")
-    check(world.state.time.year == 0.5 and world.state.amount.H == 5.0, "No double-counted migration time")
     dispose(world)
-    dispose(restored)
 
     world = fixture()
     world.entities.N.output_and = {"He": 1.0}
@@ -106,5 +87,5 @@ func run() -> void:
     dispose(world)
     check(Clock.processed_year(0.099) == 0.0, "Do not round a genuine incomplete tenth forward")
     check(Clock.processed_year(1e9 + 0.45) == 1e9 + 0.4, "Large ages preserve fractional precision")
-    print("Time migration: %d checks, %d failures" % [checks, failures])
+    print("Time state: %d checks, %d failures" % [checks, failures])
     quit(0 if failures == 0 else 1)
diff --git a/world/owniverse/owniverse.gd b/world/owniverse/owniverse.gd
index 71e8d18..254ad92 100644
--- a/world/owniverse/owniverse.gd
+++ b/world/owniverse/owniverse.gd
@@ -10,6 +10,9 @@ var entities: Dictionary[String, OwniverseEntity] = {}
 var entity_groups: Dictionary[String, Array] = {}
 var entity_event_groups: Dictionary[String, Array] = {}
 
+var _group_members: Dictionary = {}
+var _indexed_entity_count: int = -1
+
 var items_to_update: Dictionary[String, float] = {}
 
 var auto_production: Array = []
@@ -32,6 +35,18 @@ var state: Dictionary = {
     'amount': {},
     'distribution': {},
     'auto_resources': {},
+    'auto_star_deficits': {},
+    'production_remainders': {},
+    'resource_remainders': {'basic': {}, 'automatic': {}},
+    'evolution_remainders': {},
+    'life_remainders': {},
+    'planet_remainders': {},
+    'blast_remainders': {},
+    'destruction_remainders': {},
+    'civilization_remainders': {},
+    'civilization_stats': {},
+    'civilization_homes': {},
+    'ethics': {},
     'stats': {
         'total_amount': {},
     }
@@ -57,19 +72,9 @@ func evolute(delta: float) -> void:
     _evolute_to_datetime(datetime)
 
 
-## Legacy saves may have up to 0.9 unprocessed years. Process them exactly once,
-## without changing accumulated time or discarding production/evolution.
-func migrate_time_precision() -> void:
-    if state.version == SimulationTime.LEGACY_VERSION:
-        _evolute_to_datetime(float(state.time.datetime))
-
-
-# Old saves have counts but no life ages. Start only missing cohorts at load time.
 func initialize_life_batches() -> void:
     CivilizationState.detach_space_civilizations(state, Global.CivilizationRules)
     CivilizationState.enforce_capacity(self, state, Global.CivilizationRules, state.time.datetime)
-    if state.get("life_version", 0) >= 3:
-        return
     var physical: Dictionary = _physical_amounts(state)
     for id in entities:
         if entities[id].life_rule.is_empty():
@@ -78,19 +83,22 @@ func initialize_life_batches() -> void:
         for batch: Dictionary in state.batches.get(id, []):
             tracked += batch.amount
         _append_batch(state, id, maxf(0.0, physical.get(id, 0.0) - tracked), state.time.datetime, state.time.datetime)
-    state.life_version = 3
     new_state = state
 
 
 func _evolute_to_datetime(datetime: float) -> void:
-    initialize_life_batches()
+    # Reconcile only when simulation advances.
+    # Fractional frame updates cannot change capacity or populations.
+    var processed_year: float = SimulationTime.processed_year(datetime)
+    if processed_year > state.time.year:
+        initialize_life_batches()
     var previous: Dictionary = state
     var next: Dictionary = previous.duplicate_deep()
     next.version = SimulationTime.STATE_VERSION
     next.speed = clampi(int(previous.speed), 1, Global.SPEED_LIMIT)
     next.speed_in_year = pow(10.0, next.speed - 1)
     var from_year: float = previous.time.year
-    var to_year: float = SimulationTime.processed_year(datetime)
+    var to_year: float = processed_year
     if to_year > from_year:
         var quantities: Dictionary = _physical_amounts(previous)
         var distribution: Dictionary = _normalize_distribution(quantities)
@@ -147,13 +155,26 @@ func _add_time_delta(delta: float) -> Dictionary:
     return {"datetime": new_datetime, "year": SimulationTime.processed_year(new_datetime)}
 
 
+## Rebuild after changing group_as or replacing definitions without changing their count.
+## Adding/removing definitions is detected automatically during initialization.
+func rebuild_group_index() -> void:
+    _group_members.clear()
+    for id in entities:
+        var group: String = entities[id].group_as
+        if not _group_members.has(group):
+            _group_members[group] = []
+        _group_members[group].append(id)
+    _indexed_entity_count = entities.size()
+
+
+func _ensure_group_index() -> void:
+    if _indexed_entity_count != entities.size():
+        rebuild_group_index()
+
+
 func _is_group(id: String) -> bool:
-    if entity_groups.has(id):
-        return true
-    for entity: OwniverseEntity in entities.values():
-        if entity.group_as == id:
-            return true
-    return false
+    _ensure_group_index()
+    return entity_groups.has(id) or _group_members.has(id)
 
 
 func _physical_amounts(source: Dictionary) -> Dictionary:
@@ -171,11 +192,8 @@ func _physical_amounts(source: Dictionary) -> Dictionary:
 func _members(id: String) -> Array:
     if not _is_group(id):
         return [id]
-    var members: Array = []
-    for key in entities:
-        if entities[key].group_as == id:
-            members.append(key)
-    return members
+    # Callers may modify the returned array without changing the index.
+    return _group_members.get(id, []).duplicate()
 
 
 func _available(source: Dictionary, id: String) -> float:
@@ -342,6 +360,12 @@ func _append_batch(target: Dictionary, id: String, amount: float,
     var window_index: float = floorf((cursor - origin) / batch_duration)
     if origin + (window_index + 1.0) * batch_duration <= cursor:
         window_index += 1.0
+    var batches_by_start: Dictionary = {}
+    for existing: Dictionary in batches:
+        var start: float = existing.get("created_from", -INF)
+        if not batches_by_start.has(start):
+            batches_by_start[start] = []
+        batches_by_start[start].append(existing)
     while true:
         var window_start: float = origin + window_index * batch_duration
         var window_end: float = origin + (window_index + 1.0) * batch_duration
@@ -353,7 +377,7 @@ func _append_batch(target: Dictionary, id: String, amount: float,
         if duration > 0.0 and part_end < created_to:
             part_amount = floorf(amount * (part_end - created_from) / duration) - (amount - remaining_amount)
         var batch: Dictionary = {}
-        for existing: Dictionary in batches:
+        for existing: Dictionary in batches_by_start.get(window_start, []):
             if existing.get("created_from", -INF) == window_start and existing.start_year == window_start + lifespan and existing.end_year == window_end + lifespan:
                 batch = existing
                 break
@@ -366,6 +390,9 @@ func _append_batch(target: Dictionary, id: String, amount: float,
                 "amount": 0.0,
             }
             batches.append(batch)
+            if not batches_by_start.has(window_start):
+                batches_by_start[window_start] = []
+            batches_by_start[window_start].append(batch)
         batch.amount += part_amount
         remaining_amount -= part_amount
         if duration == 0.0 or part_end >= created_to:
@@ -548,12 +575,13 @@ func _produce_newborn_lifetime(target: Dictionary, id: String, count: float,
     if products.is_empty() or count <= 0.0:
         return
     var object_years: float = count * maxf(0.0, to_year - (born_from + born_to) * 0.5)
+    var previous_amounts: Dictionary = {}
+    for old: Dictionary in before_batches:
+        var start: float = old.get("created_from", -INF)
+        if not previous_amounts.has(start):
+            previous_amounts[start] = old.amount
     for batch: Dictionary in target.batches.get(id, []):
-        var added: float = batch.amount
-        for old: Dictionary in before_batches:
-            if old.get("created_from", -INF) == batch.get("created_from", INF):
-                added -= old.amount
-                break
+        var added: float = batch.amount - previous_amounts.get(batch.get("created_from", INF), 0.0)
         object_years -= maxf(0.0, added) * _expired_years(to_year, batch.start_year, batch.end_year)
     object_years = maxf(0.0, object_years)
     for resource in products:
@@ -623,7 +651,10 @@ func _evolve_batches(target: Dictionary, to_year: float) -> void:
 func _evolve_batch_generation(target: Dictionary, to_year: float) -> bool:
     var quantities: Dictionary = _physical_amounts(target)
     var expired: Dictionary = {}
-    var preview: Dictionary = target.duplicate(true)
+    var preview: Dictionary = {"batches": {}}
+    for id in target.batches:
+        if entities.has(id) and entities[id].destroy_level > 0:
+            preview.batches[id] = target.batches[id].duplicate(true)
     for id in target.batches.keys():
         if not entities.has(id) or entities[id].destroy_level <= 0:
             continue
@@ -741,7 +772,11 @@ func _evolve_batch_generation(target: Dictionary, to_year: float) -> bool:
 
 # Plan all bindings on a copy, reserving specific types before broader groups.
 func _bind_full(target: Dictionary, amounts: Dictionary) -> bool:
-    var trial: Dictionary = target.duplicate(true)
+    # Binding only mutates free amounts and owners' holdings.
+    var trial: Dictionary = {
+        "amount": target.amount.duplicate(),
+        "binds": target.binds.duplicate(true),
+    }
     var requests: Array = []
     for owner_id in amounts:
         if not entities.has(owner_id):
@@ -777,7 +812,12 @@ func _try_production(target: Dictionary, entity: OwniverseEntity, amount: float,
         automatic: bool = false) -> bool:
     if amount <= 0.0 or amount != floorf(amount):
         return false
-    var trial: Dictionary = target.duplicate(true)
+    var trial: Dictionary = target.duplicate()
+    trial.amount = target.amount.duplicate()
+    trial.binds = target.binds.duplicate(true)
+    trial.auto_resources = target.auto_resources.duplicate()
+    trial.batches = target.batches.duplicate()
+    var copied_batches: Dictionary = {}
     for resource in entity.cost:
         var cost: float = roundf(maxf(0.0, entity.cost[resource]) * amount)
         if automatic and trial.auto_resources.get(resource, 0.0) < cost:
@@ -792,6 +832,10 @@ func _try_production(target: Dictionary, entity: OwniverseEntity, amount: float,
         if automatic:
             trial.auto_resources[resource] = maxf(0.0, trial.auto_resources.get(resource, 0.0) - cost)
         for id in taken:
+            # Isolate only batches actually touched by this transaction.
+            if trial.batches.has(id) and not copied_batches.has(id):
+                trial.batches[id] = trial.batches[id].duplicate(true)
+                copied_batches[id] = true
             var factor: float = 1.0 - taken[id] / before[id] if before.get(id, 0.0) > 0.0 else 0.0
             _scale_batches(trial, id, factor)
     if not _bind_new_owners(trial, {entity.id: amount}, true):
diff --git a/world/owniverse/simulation_time.gd b/world/owniverse/simulation_time.gd
index 1007f21..83773ee 100644
--- a/world/owniverse/simulation_time.gd
+++ b/world/owniverse/simulation_time.gd
@@ -1,7 +1,6 @@
 extends RefCounted
 ## datetime is accumulated time; year is the last processed tenth of a year.
 const STATE_VERSION: String = "0.1.1"
-const LEGACY_VERSION: String = "0.1.0"
 
 static func processed_year(datetime: float) -> float:
     # Remove only sub-nanotick accumulation noise at decimal boundaries.