diff --git a/client b/client
index da1557a2..827e6a40 160000
--- a/client
+++ b/client
@@ -1 +1 @@
-Subproject commit da1557a2d4a08be07f7c3af93529aa240a060744
+Subproject commit 827e6a408a9f3df5f306461d3ade22f08e957c62
diff --git a/common/proto/accounting.proto b/common/proto/accounting.proto
index 534324ba..ae298c70 100644
--- a/common/proto/accounting.proto
+++ b/common/proto/accounting.proto
@@ -76,7 +76,8 @@ service Accounting {
 
 message EnsureAccountRequest {
   string profile_name = 1;
-  repeated string segments = 2;
+  // Slash-delimited root-to-leaf account path, for example "123/12/1".
+  string account = 2;
   // Currency accepted by source postings to the leaf account. Empty uses the
   // profile accounting currency. Missing ancestors are created in the profile
   // accounting currency.
@@ -87,9 +88,8 @@ message Account {
   int64 id = 1;
   optional int64 parent_account_id = 2;
   string segment = 3;
-  // Root-to-leaf path of this account. Same shape as the request that created
-  // it; the server never joins segments into a delimited code.
-  repeated string segments = 4;
+  // Slash-delimited root-to-leaf account path.
+  string account = 4;
   string denomination_currency = 5;
 }
 
@@ -161,9 +161,8 @@ message PostJournalRequest {
 
 message JournalLineInput {
   JournalSide side = 1;
-  // Parsed account path segments. The client owns presentation parsing; the
-  // server accepts no delimiter-encoded account string.
-  repeated string account_segments = 2;
+  // Slash-delimited root-to-leaf account path.
+  string account = 2;
   string amount = 3;
   string description = 4;
 }
@@ -281,8 +280,8 @@ message JournalLine {
   int64 id = 1;
   int32 line_number = 2;
   JournalSide side = 3;
-  // Root-to-leaf path of the posted account, as sent on JournalLineInput.
-  repeated string account_segments = 4;
+  // Slash-delimited root-to-leaf path of the posted account.
+  string account = 4;
   string amount = 5;
   string description = 6;
   bool deleted = 7;
@@ -379,8 +378,8 @@ message ListPeriodBalancesRequest {
 
 message PeriodBalance {
   int64 period_id = 1;
-  // Root-to-leaf path of the account this frozen balance belongs to.
-  repeated string account_segments = 2;
+  // Slash-delimited root-to-leaf path of this frozen balance's account.
+  string account = 2;
   string currency = 3;
   // Signed nets use debit-positive convention.
   string opening_balance = 4;
@@ -393,7 +392,7 @@ message PeriodDenominationBalance {
   int64 period_id = 1;
   // Exact denominated account. Unlike book balances, this quantity is not
   // rolled up into parent accounts with a different denomination.
-  repeated string account_segments = 2;
+  string account = 2;
   string denomination_currency = 3;
   // Signed nets use debit-positive convention and remain in the denomination
   // currency without conversion during carry-forward.
@@ -424,13 +423,13 @@ message MapOpeningBalanceAccountRequest {
   // Open period whose profile receives the opening balance. Its configured
   // previous_period_id identifies the source profile and period.
   int64 target_period_id = 1;
-  repeated string source_account_segments = 2;
-  repeated string target_account_segments = 3;
+  string source_account = 2;
+  string target_account = 3;
 }
 
 message UnmapOpeningBalanceAccountRequest {
   int64 target_period_id = 1;
-  repeated string target_account_segments = 2;
+  string target_account = 2;
 }
 
 message UnmapOpeningBalanceAccountResponse {
@@ -453,9 +452,9 @@ message OpeningBalanceAccountMapping {
   int64 target_period_id = 1;
   int64 source_period_id = 2;
   string source_profile_name = 3;
-  repeated string source_account_segments = 4;
+  string source_account = 4;
   string target_profile_name = 5;
-  repeated string target_account_segments = 6;
+  string target_account = 6;
   string currency = 7;
   // Signed balances use the debit-positive convention.
   string opening_balance = 8;
@@ -478,7 +477,7 @@ message OpeningBalanceAccountMapping {
 message UnmappedSourceBalance {
   int64 source_period_id = 1;
   string source_profile_name = 2;
-  repeated string source_account_segments = 3;
+  string source_account = 3;
   string currency = 4;
   // Signed portion not covered by a mapping, using the debit-positive
   // convention. This is never zero and may be less than the account's
@@ -490,7 +489,7 @@ message UnmappedSourceBalance {
 message UnmappedSourceDenominationBalance {
   int64 source_period_id = 1;
   string source_profile_name = 2;
-  repeated string source_account_segments = 3;
+  string source_account = 3;
   string denomination_currency = 4;
   // Exact foreign-currency quantity that no mapping carries forward.
   string unmapped_quantity = 5;
diff --git a/common/proto/table_structure.proto b/common/proto/table_structure.proto
index 70ea77b7..df653545 100644
--- a/common/proto/table_structure.proto
+++ b/common/proto/table_structure.proto
@@ -46,14 +46,14 @@ message GetTableStructureResponse {
 message TableStructureResponse {
   // Columns of the physical table, including system columns (id, deleted,
   // created_at, row_revision), user-defined columns, and any foreign-key columns such as
-  // named by whoever declared each link, plus the dedicated "account_id" on
+  // named by whoever declared each link, plus the dedicated "account" on
   // ACCOUNTING-enabled tables. May be empty if the physical table is missing.
   repeated TableColumn columns = 1;
 }
 
 // One physical column entry as reported by information_schema.
 message TableColumn {
-  // Column name exactly as defined in PostgreSQL.
+  // Public column name. Physical account_id columns are exposed as account.
   string name = 1;
 
   // Normalized data type string derived from information_schema:
diff --git a/common/proto/tables_data.proto b/common/proto/tables_data.proto
index 2d95c3fe..968851bb 100644
--- a/common/proto/tables_data.proto
+++ b/common/proto/tables_data.proto
@@ -62,7 +62,7 @@ service TablesData {
   // - Validates profile and table definition
   // - Returns all columns as strings (COALESCE(col::TEXT, '') AS col)
   //   including: id, deleted, row_revision, all user-defined columns, and FK columns
-  //   named by whoever declared each link, plus "account_id" on
+  //   named by whoever declared each link, plus "account" on
   //   ACCOUNTING-enabled tables
   // - Fails with NOT_FOUND if record does not exist or is soft-deleted
   // - If the physical table is missing but the definition exists, returns INTERNAL
@@ -102,7 +102,7 @@ message PostTableDataRequest {
   // - System/FK columns:
   //    • "deleted" (BOOLEAN), optional; default FALSE if not provided
   //    • one BIGINT per link, named by whoever declared it
-  //    • "account_id" (BIGINT) on ACCOUNTING-enabled tables
+  //    • "account" (slash-delimited account string) on ACCOUNTING-enabled tables
   //
   // Type expectations by SQL type:
   // - TEXT: string value; empty string is treated as NULL
@@ -251,7 +251,7 @@ message GetTableDataResponse {
   // - id, deleted
   // - all user-defined columns from the table definition
   // - one column per link, named by whoever declared it
-  // - account_id for ACCOUNTING-enabled tables
+  // - account for ACCOUNTING-enabled tables
   //
   // All values are returned as TEXT via col::TEXT and COALESCEed to empty string
   // (NULL becomes ""). The row is returned only if deleted = FALSE.
diff --git a/common/src/proto/descriptor.bin b/common/src/proto/descriptor.bin
index a0411d5e..e106dc3f 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 15e13f9d..f0278312 100644
--- a/common/src/proto/komp_ac.accounting.rs
+++ b/common/src/proto/komp_ac.accounting.rs
@@ -3,8 +3,9 @@
 pub struct EnsureAccountRequest {
     #[prost(string, tag = "1")]
     pub profile_name: ::prost::alloc::string::String,
-    #[prost(string, repeated, tag = "2")]
-    pub segments: ::prost::alloc::vec::Vec<::prost::alloc::string::String>,
+    /// Slash-delimited root-to-leaf account path, for example "123/12/1".
+    #[prost(string, tag = "2")]
+    pub account: ::prost::alloc::string::String,
     /// Currency accepted by source postings to the leaf account. Empty uses the
     /// profile accounting currency. Missing ancestors are created in the profile
     /// accounting currency.
@@ -19,10 +20,9 @@ pub struct Account {
     pub parent_account_id: ::core::option::Option<i64>,
     #[prost(string, tag = "3")]
     pub segment: ::prost::alloc::string::String,
-    /// Root-to-leaf path of this account. Same shape as the request that created
-    /// it; the server never joins segments into a delimited code.
-    #[prost(string, repeated, tag = "4")]
-    pub segments: ::prost::alloc::vec::Vec<::prost::alloc::string::String>,
+    /// Slash-delimited root-to-leaf account path.
+    #[prost(string, tag = "4")]
+    pub account: ::prost::alloc::string::String,
     #[prost(string, tag = "5")]
     pub denomination_currency: ::prost::alloc::string::String,
 }
@@ -68,10 +68,9 @@ pub struct PostJournalRequest {
 pub struct JournalLineInput {
     #[prost(enumeration = "JournalSide", tag = "1")]
     pub side: i32,
-    /// Parsed account path segments. The client owns presentation parsing; the
-    /// server accepts no delimiter-encoded account string.
-    #[prost(string, repeated, tag = "2")]
-    pub account_segments: ::prost::alloc::vec::Vec<::prost::alloc::string::String>,
+    /// Slash-delimited root-to-leaf account path.
+    #[prost(string, tag = "2")]
+    pub account: ::prost::alloc::string::String,
     #[prost(string, tag = "3")]
     pub amount: ::prost::alloc::string::String,
     #[prost(string, tag = "4")]
@@ -238,9 +237,9 @@ pub struct JournalLine {
     pub line_number: i32,
     #[prost(enumeration = "JournalSide", tag = "3")]
     pub side: i32,
-    /// Root-to-leaf path of the posted account, as sent on JournalLineInput.
-    #[prost(string, repeated, tag = "4")]
-    pub account_segments: ::prost::alloc::vec::Vec<::prost::alloc::string::String>,
+    /// Slash-delimited root-to-leaf path of the posted account.
+    #[prost(string, tag = "4")]
+    pub account: ::prost::alloc::string::String,
     #[prost(string, tag = "5")]
     pub amount: ::prost::alloc::string::String,
     #[prost(string, tag = "6")]
@@ -386,9 +385,9 @@ pub struct ListPeriodBalancesRequest {
 pub struct PeriodBalance {
     #[prost(int64, tag = "1")]
     pub period_id: i64,
-    /// Root-to-leaf path of the account this frozen balance belongs to.
-    #[prost(string, repeated, tag = "2")]
-    pub account_segments: ::prost::alloc::vec::Vec<::prost::alloc::string::String>,
+    /// Slash-delimited root-to-leaf path of this frozen balance's account.
+    #[prost(string, tag = "2")]
+    pub account: ::prost::alloc::string::String,
     #[prost(string, tag = "3")]
     pub currency: ::prost::alloc::string::String,
     /// Signed nets use debit-positive convention.
@@ -407,8 +406,8 @@ pub struct PeriodDenominationBalance {
     pub period_id: i64,
     /// Exact denominated account. Unlike book balances, this quantity is not
     /// rolled up into parent accounts with a different denomination.
-    #[prost(string, repeated, tag = "2")]
-    pub account_segments: ::prost::alloc::vec::Vec<::prost::alloc::string::String>,
+    #[prost(string, tag = "2")]
+    pub account: ::prost::alloc::string::String,
     #[prost(string, tag = "3")]
     pub denomination_currency: ::prost::alloc::string::String,
     /// Signed nets use debit-positive convention and remain in the denomination
@@ -453,23 +452,17 @@ pub struct MapOpeningBalanceAccountRequest {
     /// previous_period_id identifies the source profile and period.
     #[prost(int64, tag = "1")]
     pub target_period_id: i64,
-    #[prost(string, repeated, tag = "2")]
-    pub source_account_segments: ::prost::alloc::vec::Vec<
-        ::prost::alloc::string::String,
-    >,
-    #[prost(string, repeated, tag = "3")]
-    pub target_account_segments: ::prost::alloc::vec::Vec<
-        ::prost::alloc::string::String,
-    >,
+    #[prost(string, tag = "2")]
+    pub source_account: ::prost::alloc::string::String,
+    #[prost(string, tag = "3")]
+    pub target_account: ::prost::alloc::string::String,
 }
 #[derive(Clone, PartialEq, Eq, Hash, ::prost::Message)]
 pub struct UnmapOpeningBalanceAccountRequest {
     #[prost(int64, tag = "1")]
     pub target_period_id: i64,
-    #[prost(string, repeated, tag = "2")]
-    pub target_account_segments: ::prost::alloc::vec::Vec<
-        ::prost::alloc::string::String,
-    >,
+    #[prost(string, tag = "2")]
+    pub target_account: ::prost::alloc::string::String,
 }
 #[derive(Clone, Copy, PartialEq, Eq, Hash, ::prost::Message)]
 pub struct UnmapOpeningBalanceAccountResponse {
@@ -489,16 +482,12 @@ pub struct OpeningBalanceAccountMapping {
     pub source_period_id: i64,
     #[prost(string, tag = "3")]
     pub source_profile_name: ::prost::alloc::string::String,
-    #[prost(string, repeated, tag = "4")]
-    pub source_account_segments: ::prost::alloc::vec::Vec<
-        ::prost::alloc::string::String,
-    >,
+    #[prost(string, tag = "4")]
+    pub source_account: ::prost::alloc::string::String,
     #[prost(string, tag = "5")]
     pub target_profile_name: ::prost::alloc::string::String,
-    #[prost(string, repeated, tag = "6")]
-    pub target_account_segments: ::prost::alloc::vec::Vec<
-        ::prost::alloc::string::String,
-    >,
+    #[prost(string, tag = "6")]
+    pub target_account: ::prost::alloc::string::String,
     #[prost(string, tag = "7")]
     pub currency: ::prost::alloc::string::String,
     /// Signed balances use the debit-positive convention.
@@ -536,10 +525,8 @@ pub struct UnmappedSourceBalance {
     pub source_period_id: i64,
     #[prost(string, tag = "2")]
     pub source_profile_name: ::prost::alloc::string::String,
-    #[prost(string, repeated, tag = "3")]
-    pub source_account_segments: ::prost::alloc::vec::Vec<
-        ::prost::alloc::string::String,
-    >,
+    #[prost(string, tag = "3")]
+    pub source_account: ::prost::alloc::string::String,
     #[prost(string, tag = "4")]
     pub currency: ::prost::alloc::string::String,
     /// Signed portion not covered by a mapping, using the debit-positive
@@ -556,10 +543,8 @@ pub struct UnmappedSourceDenominationBalance {
     pub source_period_id: i64,
     #[prost(string, tag = "2")]
     pub source_profile_name: ::prost::alloc::string::String,
-    #[prost(string, repeated, tag = "3")]
-    pub source_account_segments: ::prost::alloc::vec::Vec<
-        ::prost::alloc::string::String,
-    >,
+    #[prost(string, tag = "3")]
+    pub source_account: ::prost::alloc::string::String,
     #[prost(string, tag = "4")]
     pub denomination_currency: ::prost::alloc::string::String,
     /// Exact foreign-currency quantity that no mapping carries forward.
diff --git a/common/src/proto/komp_ac.table_structure.rs b/common/src/proto/komp_ac.table_structure.rs
index 1d17cade..6f49055c 100644
--- a/common/src/proto/komp_ac.table_structure.rs
+++ b/common/src/proto/komp_ac.table_structure.rs
@@ -26,7 +26,7 @@ pub struct GetTableStructureResponse {
 pub struct TableStructureResponse {
     /// Columns of the physical table, including system columns (id, deleted,
     /// created_at, row_revision), user-defined columns, and any foreign-key columns such as
-    /// named by whoever declared each link, plus the dedicated "account_id" on
+    /// named by whoever declared each link, plus the dedicated "account" on
     /// ACCOUNTING-enabled tables. May be empty if the physical table is missing.
     #[prost(message, repeated, tag = "1")]
     pub columns: ::prost::alloc::vec::Vec<TableColumn>,
@@ -34,7 +34,7 @@ pub struct TableStructureResponse {
 /// One physical column entry as reported by information_schema.
 #[derive(Clone, PartialEq, Eq, Hash, ::prost::Message)]
 pub struct TableColumn {
-    /// Column name exactly as defined in PostgreSQL.
+    /// Public column name. Physical account_id columns are exposed as account.
     #[prost(string, tag = "1")]
     pub name: ::prost::alloc::string::String,
     /// Normalized data type string derived from information_schema:
diff --git a/common/src/proto/komp_ac.tables_data.rs b/common/src/proto/komp_ac.tables_data.rs
index ef531db7..deebf2d7 100644
--- a/common/src/proto/komp_ac.tables_data.rs
+++ b/common/src/proto/komp_ac.tables_data.rs
@@ -18,7 +18,7 @@ pub struct PostTableDataRequest {
     /// * System/FK columns:
     ///   • "deleted" (BOOLEAN), optional; default FALSE if not provided
     ///   • one BIGINT per link, named by whoever declared it
-    ///   • "account_id" (BIGINT) on ACCOUNTING-enabled tables
+    ///   • "account" (slash-delimited account string) on ACCOUNTING-enabled tables
     ///
     /// Type expectations by SQL type:
     ///
@@ -191,7 +191,7 @@ pub struct GetTableDataResponse {
     /// * id, deleted
     /// * all user-defined columns from the table definition
     /// * one column per link, named by whoever declared it
-    /// * account_id for ACCOUNTING-enabled tables
+    /// * account for ACCOUNTING-enabled tables
     ///
     /// All values are returned as TEXT via col::TEXT and COALESCEed to empty string
     /// (NULL becomes ""). The row is returned only if deleted = FALSE.
@@ -482,7 +482,7 @@ pub mod tables_data_client {
         /// * Validates profile and table definition
         /// * Returns all columns as strings (COALESCE(col::TEXT, '') AS col)
         ///  including: id, deleted, row_revision, all user-defined columns, and FK columns
-        ///  named by whoever declared each link, plus "account_id" on
+        ///  named by whoever declared each link, plus "account" on
         ///  ACCOUNTING-enabled tables
         /// * Fails with NOT_FOUND if record does not exist or is soft-deleted
         /// * If the physical table is missing but the definition exists, returns INTERNAL
@@ -675,7 +675,7 @@ pub mod tables_data_server {
         /// * Validates profile and table definition
         /// * Returns all columns as strings (COALESCE(col::TEXT, '') AS col)
         ///  including: id, deleted, row_revision, all user-defined columns, and FK columns
-        ///  named by whoever declared each link, plus "account_id" on
+        ///  named by whoever declared each link, plus "account" on
         ///  ACCOUNTING-enabled tables
         /// * Fails with NOT_FOUND if record does not exist or is soft-deleted
         /// * If the physical table is missing but the definition exists, returns INTERNAL
diff --git a/common/src/system_column.rs b/common/src/system_column.rs
index 0a09c3cb..23171634 100644
--- a/common/src/system_column.rs
+++ b/common/src/system_column.rs
@@ -43,6 +43,7 @@ pub const TRAILING_SYSTEM_COLUMNS: [SystemColumn; 1] = [SystemColumn {
 /// Its declaration names that profile's schema, so it is built where the
 /// profile is known rather than spelled out here.
 pub const ACCOUNT_REFERENCE_COLUMN: &str = "account_id";
+pub const ACCOUNT_API_COLUMN: &str = "account";
 
 /// Every system column name, whether or not the column is on a given table.
 ///
@@ -59,12 +60,13 @@ pub fn system_column_names() -> impl Iterator<Item = &'static str> {
 /// Whether `name` is a system column: a name that is safe to show a client
 /// as-is, and that a user may not claim for a column alias or a table.
 pub fn is_system_column(name: &str) -> bool {
-    system_column_names().any(|system_name| system_name == name)
+    name == ACCOUNT_API_COLUMN || system_column_names().any(|system_name| system_name == name)
 }
 
 /// The system column names in a message, as `'id', 'deleted', ...`.
 pub fn system_column_name_list() -> String {
     system_column_names()
+        .chain(std::iter::once(ACCOUNT_API_COLUMN))
         .map(|name| format!("'{name}'"))
         .collect::<Vec<_>>()
         .join(", ")
@@ -73,7 +75,8 @@ pub fn system_column_name_list() -> String {
 #[cfg(test)]
 mod tests {
     use super::{
-        ACCOUNT_REFERENCE_COLUMN, is_system_column, system_column_name_list, system_column_names,
+        ACCOUNT_API_COLUMN, ACCOUNT_REFERENCE_COLUMN, is_system_column, system_column_name_list,
+        system_column_names,
     };
 
     #[test]
@@ -86,6 +89,7 @@ mod tests {
     #[test]
     fn a_conditional_column_is_reserved_on_every_table() {
         assert!(is_system_column(ACCOUNT_REFERENCE_COLUMN));
+        assert!(is_system_column(ACCOUNT_API_COLUMN));
     }
 
     #[test]
@@ -98,7 +102,7 @@ mod tests {
     fn the_name_list_reads_as_a_sentence_fragment() {
         assert_eq!(
             system_column_name_list(),
-            "'id', 'deleted', 'row_revision', 'created_at', 'account_id'"
+            "'id', 'deleted', 'row_revision', 'created_at', 'account_id', 'account'"
         );
     }
 }
diff --git a/server b/server
index 1fe9ffa7..d29f1305 160000
--- a/server
+++ b/server
@@ -1 +1 @@
-Subproject commit 1fe9ffa75942f81d511506d4855f66e945071d69
+Subproject commit d29f130523766cf7beb44e478950aca558fa2b23