diff --git a/assets/js/hooks/Mapper/components/mapInterface/widgets/SystemStructures/SystemStructuresDialog/SystemStructuresDialog.tsx b/assets/js/hooks/Mapper/components/mapInterface/widgets/SystemStructures/SystemStructuresDialog/SystemStructuresDialog.tsx
index 597ba637..f39c41cc 100644
--- a/assets/js/hooks/Mapper/components/mapInterface/widgets/SystemStructures/SystemStructuresDialog/SystemStructuresDialog.tsx
+++ b/assets/js/hooks/Mapper/components/mapInterface/widgets/SystemStructures/SystemStructuresDialog/SystemStructuresDialog.tsx
@@ -30,9 +30,6 @@ export const SystemStructuresDialog: React.FC<StructuresEditDialogProps> = ({
 
   const { outCommand } = useMapRootState();
 
-  const [prevQuery, setPrevQuery] = useState('');
-  const [prevResults, setPrevResults] = useState<{ label: string; value: string }[]>([]);
-
   useEffect(() => {
     if (structure) {
       setEditData(structure);
@@ -46,34 +43,24 @@ export const SystemStructuresDialog: React.FC<StructuresEditDialogProps> = ({
   // Searching corporation owners via auto-complete
   const searchOwners = useCallback(
     async (e: { query: string }) => {
-      const newQuery = e.query.trim();
-      if (!newQuery) {
+      const query = e.query.trim();
+      if (!query) {
         setOwnerSuggestions([]);
         return;
       }
 
-      // If user typed more text but we have partial match in prevResults
-      if (newQuery.startsWith(prevQuery) && prevResults.length > 0) {
-        const filtered = prevResults.filter(item => item.label.toLowerCase().includes(newQuery.toLowerCase()));
-        setOwnerSuggestions(filtered);
-        return;
-      }
-
       try {
-        // TODO fix it
         const { results = [] } = await outCommand({
           type: OutCommand.getCorporationNames,
-          data: { search: newQuery },
+          data: { search: query },
         });
         setOwnerSuggestions(results);
-        setPrevQuery(newQuery);
-        setPrevResults(results);
       } catch (err) {
         console.error('Failed to fetch owners:', err);
         setOwnerSuggestions([]);
       }
     },
-    [prevQuery, prevResults, outCommand],
+    [outCommand],
   );
 
   const handleChange = (field: keyof StructureItem, val: string | Date) => {
@@ -122,7 +109,6 @@ export const SystemStructuresDialog: React.FC<StructuresEditDialogProps> = ({
     // fetch corporation ticker if we have an ownerId
     if (editData.ownerId) {
       try {
-        // TODO fix it
         const { ticker } = await outCommand({
           type: OutCommand.getCorporationTicker,
           data: { corp_id: editData.ownerId },
diff --git a/lib/wanderer_app/map/operations/signatures.ex b/lib/wanderer_app/map/operations/signatures.ex
index 1909177f..7fdbcd30 100644
--- a/lib/wanderer_app/map/operations/signatures.ex
+++ b/lib/wanderer_app/map/operations/signatures.ex
@@ -5,9 +5,36 @@ defmodule WandererApp.Map.Operations.Signatures do
 
   require Logger
   alias WandererApp.Map.Operations
-  alias WandererApp.Api.{MapSystem, MapSystemSignature}
+  alias WandererApp.Api.{Character, MapSystem, MapSystemSignature}
   alias WandererApp.Map.Server
 
+  # Private helper to validate character_eve_id from params
+  # If character_eve_id is provided in params, validates it exists in the system
+  # If not provided, falls back to the owner's character ID
+  @spec validate_character_eve_id(map(), String.t()) ::
+          {:ok, String.t()} | {:error, :invalid_character}
+  defp validate_character_eve_id(params, fallback_char_id) do
+    case Map.get(params, "character_eve_id") do
+      nil ->
+        # No character_eve_id provided, use fallback (owner's character)
+        {:ok, fallback_char_id}
+
+      provided_char_id when is_binary(provided_char_id) ->
+        # Validate the provided character_eve_id exists
+        case Character.by_eve_id(provided_char_id) do
+          {:ok, _character} ->
+            {:ok, provided_char_id}
+
+          _ ->
+            {:error, :invalid_character}
+        end
+
+      _ ->
+        # Invalid format
+        {:error, :invalid_character}
+    end
+  end
+
   @spec list_signatures(String.t()) :: [map()]
   def list_signatures(map_id) do
     systems = Operations.list_systems(map_id)
@@ -42,10 +69,11 @@ defmodule WandererApp.Map.Operations.Signatures do
       )
       when is_integer(solar_system_id) do
     # Convert solar_system_id to system_id for internal use
-    with {:ok, system} <- MapSystem.by_map_id_and_solar_system_id(map_id, solar_system_id) do
+    with {:ok, system} <- MapSystem.by_map_id_and_solar_system_id(map_id, solar_system_id),
+         {:ok, validated_char_id} <- validate_character_eve_id(params, char_id) do
       attrs =
         params
-        |> Map.put("character_eve_id", char_id)
+        |> Map.put("character_eve_id", validated_char_id)
         |> Map.put("system_id", system.id)
         |> Map.delete("solar_system_id")
 
@@ -54,7 +82,7 @@ defmodule WandererApp.Map.Operations.Signatures do
              updated_signatures: [],
              removed_signatures: [],
              solar_system_id: solar_system_id,
-             character_id: char_id,
+             character_id: validated_char_id,
              user_id: user_id,
              delete_connection_with_sigs: false
            }) do
@@ -86,6 +114,10 @@ defmodule WandererApp.Map.Operations.Signatures do
           {:error, :unexpected_error}
       end
     else
+      {:error, :invalid_character} ->
+        Logger.error("[create_signature] Invalid character_eve_id provided")
+        {:error, :invalid_character}
+
       _ ->
         Logger.error(
           "[create_signature] System not found for solar_system_id: #{solar_system_id}"
@@ -112,7 +144,8 @@ defmodule WandererApp.Map.Operations.Signatures do
         params
       ) do
     with {:ok, sig} <- MapSystemSignature.by_id(sig_id),
-         {:ok, system} <- MapSystem.by_id(sig.system_id) do
+         {:ok, system} <- MapSystem.by_id(sig.system_id),
+         {:ok, validated_char_id} <- validate_character_eve_id(params, char_id) do
       base = %{
         "eve_id" => sig.eve_id,
         "name" => sig.name,
@@ -120,7 +153,7 @@ defmodule WandererApp.Map.Operations.Signatures do
         "group" => sig.group,
         "type" => sig.type,
         "custom_info" => sig.custom_info,
-        "character_eve_id" => char_id,
+        "character_eve_id" => validated_char_id,
         "description" => sig.description,
         "linked_system_id" => sig.linked_system_id
       }
@@ -133,7 +166,7 @@ defmodule WandererApp.Map.Operations.Signatures do
           updated_signatures: [attrs],
           removed_signatures: [],
           solar_system_id: system.solar_system_id,
-          character_id: char_id,
+          character_id: validated_char_id,
           user_id: user_id,
           delete_connection_with_sigs: false
         })
@@ -151,6 +184,10 @@ defmodule WandererApp.Map.Operations.Signatures do
         _ -> {:ok, attrs}
       end
     else
+      {:error, :invalid_character} ->
+        Logger.error("[update_signature] Invalid character_eve_id provided")
+        {:error, :invalid_character}
+
       err ->
         Logger.error("[update_signature] Unexpected error: #{inspect(err)}")
         {:error, :unexpected_error}
diff --git a/lib/wanderer_app_web/controllers/map_system_api_controller.ex b/lib/wanderer_app_web/controllers/map_system_api_controller.ex
index e184c50b..94f53284 100644
--- a/lib/wanderer_app_web/controllers/map_system_api_controller.ex
+++ b/lib/wanderer_app_web/controllers/map_system_api_controller.ex
@@ -441,18 +441,19 @@ defmodule WandererAppWeb.MapSystemAPIController do
   )
 
   def show(%{assigns: %{map_id: map_id}} = conn, %{"id" => id}) do
-    with {:ok, system_uuid} <- APIUtils.validate_uuid(id),
-         {:ok, system} <- WandererApp.Api.MapSystem.by_id(system_uuid) do
-      # Verify the system belongs to the requested map
-      if system.map_id == map_id do
-        APIUtils.respond_data(conn, APIUtils.map_system_to_json(system))
-      else
+    # Look up by solar_system_id (EVE Online integer ID)
+    case APIUtils.parse_int(id) do
+      {:ok, solar_system_id} ->
+        case Operations.get_system(map_id, solar_system_id) do
+          {:ok, system} ->
+            APIUtils.respond_data(conn, APIUtils.map_system_to_json(system))
+
+          {:error, :not_found} ->
+            {:error, :not_found}
+        end
+
+      {:error, _} ->
         {:error, :not_found}
-      end
-    else
-      {:error, %Ash.Error.Query.NotFound{}} -> {:error, :not_found}
-      {:error, _} -> {:error, :not_found}
-      error -> error
     end
   end
 
@@ -472,8 +473,22 @@ defmodule WandererAppWeb.MapSystemAPIController do
   )
 
   def create(conn, params) do
-    systems = Map.get(params, "systems", [])
-    connections = Map.get(params, "connections", [])
+    # Support both batch format {"systems": [...], "connections": [...]}
+    # and single system format {"solar_system_id": ..., ...}
+    {systems, connections} =
+      cond do
+        Map.has_key?(params, "systems") ->
+          # Batch format
+          {Map.get(params, "systems", []), Map.get(params, "connections", [])}
+
+        Map.has_key?(params, "solar_system_id") or Map.has_key?(params, :solar_system_id) ->
+          # Single system format - wrap it in an array
+          {[params], []}
+
+        true ->
+          # Empty request
+          {[], []}
+      end
 
     case Operations.upsert_systems_and_connections(conn, systems, connections) do
       {:ok, result} ->
diff --git a/lib/wanderer_app_web/router.ex b/lib/wanderer_app_web/router.ex
index 3ca6c05f..4fab1eb4 100644
--- a/lib/wanderer_app_web/router.ex
+++ b/lib/wanderer_app_web/router.ex
@@ -595,7 +595,7 @@ defmodule WandererAppWeb.Router do
   # while maintaining 100% backward compatibility with existing /api/* routes
   #
   scope "/api/v1" do
-    pipe_through :api_v1
+    pipe_through [:api_v1, :api_map]
 
     # Custom combined endpoints
     get "/maps/:map_id/systems_and_connections",