diff --git a/src/editor/action_history.gd b/src/editor/action_history.gd
index 9e5467b..cd4cf50 100644
--- a/src/editor/action_history.gd
+++ b/src/editor/action_history.gd
@@ -79,12 +79,15 @@ func commit(desc: String, before: Dictionary, after: Dictionary, merge_tag: Stri
 
 
 ## Letzte Aktion zurücknehmen. Rückgabe: Beschreibung ("" = nichts da).
+## Restore läuft IN-PLACE: doc["objects"] etc. behalten ihre Identität (Array/
+## Dict-Objekt wird geleert und neu befüllt) — bezogene Referenzen (Tests,
+## Ansichten) werden nicht zu Stale-Schnappschüssen.
 func undo() -> String:
 	if not can_undo():
 		return ""
 	var entry: Dictionary = entries[index]
 	for key in entry["before"]:
-		doc[key] = entry["before"][key].duplicate(true) if entry["before"][key] != null else null
+		_restore_block(key, entry["before"][key])
 	index -= 1
 	return str(entry.get("desc", ""))
 
@@ -96,5 +99,25 @@ func redo() -> String:
 	index += 1
 	var entry: Dictionary = entries[index]
 	for key in entry["after"]:
-		doc[key] = entry["after"][key].duplicate(true) if entry["after"][key] != null else null
-	return str(entry.get("desc", ""))
\ No newline at end of file
+		_restore_block(key, entry["after"][key])
+	return str(entry.get("desc", ""))
+
+
+func _restore_block(key: String, value: Variant) -> void:
+	if value == null:
+		doc.erase(key)
+		return
+	# Ganzen Block (Array/Dict) in-place neu befüllen — Identität bleibt erhalten.
+	var source: Variant = value.duplicate(true)
+	if source is Array:
+		var arr: Array = doc.get(key, [])
+		arr.clear()
+		arr.append_array(source)
+		doc[key] = arr
+	elif source is Dictionary:
+		var dict: Dictionary = doc.get(key, {})
+		dict.clear()
+		dict.merge(source)
+		doc[key] = dict
+	else:
+		doc[key] = source
\ No newline at end of file
diff --git a/tests/test_ux.gd b/tests/test_ux.gd
index 045af33..5d39d15 100644
--- a/tests/test_ux.gd
+++ b/tests/test_ux.gd
@@ -212,10 +212,11 @@ func _test_terrain_height() -> void:
 		"heightmap_r16_b64": Marshalls.raw_to_base64(bytes),
 	}
 	var doc2 := {"terrain": slope}
-	_check(absf(SvmapDocument.terrain_height_at(doc2, 0.0, 0.0) - 0.0) < 0.5, "Gradient: Nordkante ≈ 0 m")
-	var mid := SvmapDocument.terrain_height_at(doc2, 0.0, 80.0)
-	_check(absf(mid - 50.0) < 1.0, "Gradient: Mitte ≈ 50 m (ist %.1f)" % mid)
-	_check(absf(SvmapDocument.terrain_height_at(doc2, 0.0, 160.0) - 100.0) < 0.5, "Gradient: Südkante ≈ 100 m")
+	_check(absf(SvmapDocument.terrain_height_at(doc2, 0.0, -80.0) - 0.0) < 0.5, "Gradient: Nordkante (z=-80) ≈ 0 m")
+	var mid := SvmapDocument.terrain_height_at(doc2, 0.0, 0.0)
+	_check(absf(mid - 50.0) < 1.0, "Gradient: Mitte (z=0) ≈ 50 m (ist %.1f)" % mid)
+	_check(absf(SvmapDocument.terrain_height_at(doc2, 0.0, 80.0) - 100.0) < 0.5, "Gradient: Südkante (z=+80) ≈ 100 m")
+	_check(absf(SvmapDocument.terrain_height_at(doc2, 0.0, 160.0) - 100.0) < 0.5, "Hinter der Kante wird geclampt (100 m)")
 	_check(absf(SvmapDocument.terrain_height_at(doc2, 5000.0, -900.0) - 0.0) < 0.6, "Außerhalb-Query wird geclampt (keine Abstürze)")