diff --git a/common/build.rs b/common/build.rs
index 938f402e..fffebf01 100644
--- a/common/build.rs
+++ b/common/build.rs
@@ -38,6 +38,10 @@ fn main() -> Result<(), Box<dyn std::error::Error>> {
             ".komp_ac.table_validation.FieldValidation.locked",
             "#[serde(default)]",
         )
+        .field_attribute(
+            ".komp_ac.table_validation.UpdateFieldValidationRequest.update_mask",
+            "#[serde(skip)]",
+        )
         .field_attribute(
             ".komp_ac.table_definition.ColumnDefinition.boolean_ledger",
             "#[serde(default, alias = \"boolean_ledger_operator\")]",
diff --git a/common/proto/table_validation.proto b/common/proto/table_validation.proto
index c6187bc1..d449f1e0 100644
--- a/common/proto/table_validation.proto
+++ b/common/proto/table_validation.proto
@@ -2,6 +2,8 @@
 syntax = "proto3";
 package komp_ac.table_validation;
 
+import "google/protobuf/field_mask.proto";
+
 // This proto is the canonical server-side storage and distribution contract for
 // client validation configuration.
 //
@@ -189,6 +191,11 @@ message UpdateFieldValidationRequest {
   string tableName = 2;
   string dataKey = 3;
   FieldValidation validation = 4;
+
+  // Omitted keeps the legacy full-replacement behavior. Otherwise, only the
+  // selected FieldValidation properties are changed; selecting an absent
+  // message property deliberately removes it.
+  google.protobuf.FieldMask update_mask = 5;
 }
 
 message UpdateFieldValidationResponse {
diff --git a/common/src/proto/descriptor.bin b/common/src/proto/descriptor.bin
index 2e2427d9..d5dd41f1 100644
Binary files a/common/src/proto/descriptor.bin and b/common/src/proto/descriptor.bin differ
diff --git a/common/src/proto/komp_ac.table_validation.rs b/common/src/proto/komp_ac.table_validation.rs
index 9069662f..5401c5a5 100644
--- a/common/src/proto/komp_ac.table_validation.rs
+++ b/common/src/proto/komp_ac.table_validation.rs
@@ -159,6 +159,12 @@ pub struct UpdateFieldValidationRequest {
     pub data_key: ::prost::alloc::string::String,
     #[prost(message, optional, tag = "4")]
     pub validation: ::core::option::Option<FieldValidation>,
+    /// Omitted keeps the legacy full-replacement behavior. Otherwise, only the
+    /// selected FieldValidation properties are changed; selecting an absent
+    /// message property deliberately removes it.
+    #[prost(message, optional, tag = "5")]
+    #[serde(skip)]
+    pub update_mask: ::core::option::Option<::prost_types::FieldMask>,
 }
 #[derive(serde::Serialize, serde::Deserialize)]
 #[derive(Clone, PartialEq, Eq, Hash, ::prost::Message)]
diff --git a/komp-app/src/grpc.rs b/komp-app/src/grpc.rs
index a9183764..544a1c2f 100644
--- a/komp-app/src/grpc.rs
+++ b/komp-app/src/grpc.rs
@@ -257,6 +257,7 @@ impl GrpcClient {
             table_name,
             data_key,
             validation: Some(validation),
+            update_mask: None,
         };
         let request = self.authenticated_request(req)?;
         let resp = self
diff --git a/server b/server
index 825a5bcf..7bb3706e 160000
--- a/server
+++ b/server
@@ -1 +1 @@
-Subproject commit 825a5bcf321655ba3821718eae817982f1e40e5d
+Subproject commit 7bb3706ec6e670e1e7d6495d2f699d50a9bc41e3
diff --git a/web/src/pages/add_validation/state.rs b/web/src/pages/add_validation/state.rs
index 3cd3a17c..d3c770a1 100644
--- a/web/src/pages/add_validation/state.rs
+++ b/web/src/pages/add_validation/state.rs
@@ -109,6 +109,7 @@ impl ValidationForm {
             table_name,
             data_key: data_key.clone(),
             validation: Some(self.validation(locale, data_key)?),
+            update_mask: None,
         })
     }