diff --git a/common/proto/accounting.proto b/common/proto/accounting.proto
index be33939a..4003240d 100644
--- a/common/proto/accounting.proto
+++ b/common/proto/accounting.proto
@@ -433,16 +433,18 @@ message OpeningBalanceAccountMapping {
   string created_by_user_id = 14;
 }
 
-// A predecessor account still holding value that no mapping carries into the
-// target period. Closing the target period drops these balances silently, so
-// each one is either an account left to map or one deliberately closed out.
-message UnmappedSourceAccount {
+// A portion of a predecessor account's value that no mapping carries into the
+// target period. Closing the target period drops this value, so each entry must
+// either be covered by a broader mapping or deliberately closed out.
+message UnmappedSourceBalance {
   int64 source_period_id = 1;
   string source_profile_name = 2;
   repeated string source_account_segments = 3;
   string currency = 4;
-  // Signed balance uses the debit-positive convention, and is never zero.
-  string closing_balance = 5;
+  // Signed portion not covered by a mapping, using the debit-positive
+  // convention. This is never zero and may be less than the account's
+  // aggregate closing balance when descendants are mapped separately.
+  string unmapped_balance = 5;
   OpeningBalanceStatus status = 6;
 }
 
@@ -453,5 +455,5 @@ message ListOpeningBalanceAccountsResponse {
   // account path. Populated once the period carries balances by explicit
   // mapping only, which happens when the predecessor belongs to another
   // profile or when the period has at least one mapping of its own.
-  repeated UnmappedSourceAccount unmapped_source_accounts = 2;
+  repeated UnmappedSourceBalance unmapped_source_balances = 2;
 }
diff --git a/common/src/proto/descriptor.bin b/common/src/proto/descriptor.bin
index e9e23e75..0f01c031 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.accounting.rs b/common/src/proto/komp_ac.accounting.rs
index 65a336ea..49894310 100644
--- a/common/src/proto/komp_ac.accounting.rs
+++ b/common/src/proto/komp_ac.accounting.rs
@@ -476,11 +476,11 @@ pub struct OpeningBalanceAccountMapping {
     #[prost(string, tag = "14")]
     pub created_by_user_id: ::prost::alloc::string::String,
 }
-/// A predecessor account still holding value that no mapping carries into the
-/// target period. Closing the target period drops these balances silently, so
-/// each one is either an account left to map or one deliberately closed out.
+/// A portion of a predecessor account's value that no mapping carries into the
+/// target period. Closing the target period drops this value, so each entry must
+/// either be covered by a broader mapping or deliberately closed out.
 #[derive(Clone, PartialEq, Eq, Hash, ::prost::Message)]
-pub struct UnmappedSourceAccount {
+pub struct UnmappedSourceBalance {
     #[prost(int64, tag = "1")]
     pub source_period_id: i64,
     #[prost(string, tag = "2")]
@@ -491,9 +491,11 @@ pub struct UnmappedSourceAccount {
     >,
     #[prost(string, tag = "4")]
     pub currency: ::prost::alloc::string::String,
-    /// Signed balance uses the debit-positive convention, and is never zero.
+    /// Signed portion not covered by a mapping, using the debit-positive
+    /// convention. This is never zero and may be less than the account's
+    /// aggregate closing balance when descendants are mapped separately.
     #[prost(string, tag = "5")]
-    pub closing_balance: ::prost::alloc::string::String,
+    pub unmapped_balance: ::prost::alloc::string::String,
     #[prost(enumeration = "OpeningBalanceStatus", tag = "6")]
     pub status: i32,
 }
@@ -506,7 +508,7 @@ pub struct ListOpeningBalanceAccountsResponse {
     /// mapping only, which happens when the predecessor belongs to another
     /// profile or when the period has at least one mapping of its own.
     #[prost(message, repeated, tag = "2")]
-    pub unmapped_source_accounts: ::prost::alloc::vec::Vec<UnmappedSourceAccount>,
+    pub unmapped_source_balances: ::prost::alloc::vec::Vec<UnmappedSourceBalance>,
 }
 #[derive(Clone, Copy, Debug, PartialEq, Eq, Hash, PartialOrd, Ord, ::prost::Enumeration)]
 #[repr(i32)]