specifically need to ask for custom conversion rates

common/proto/accounting.proto

@@ -111,6 +111,13 @@ message PostJournalRequest {
   // creating. Must be empty when appending. Rejected when it falls at or before
   // the latest closed or approved accounting boundary for the profile.
   string accounting_date = 7;
+
+  // Convert this posting with the profile's own rate for the publication date
+  // instead of the ECB reference rate. False, the default, always uses ECB, even
+  // where a custom rate for that date exists. True requires one to have been
+  // entered: a missing rate is refused rather than silently converted at the
+  // official rate. Ignored when nothing needs converting.
+  bool use_custom_rate = 8;
 }
 
 message JournalLineInput {

common/proto/ecb.proto

@@ -37,10 +37,14 @@ message PreviewEcbConversionRequest {
   // conversion_context: transaction, statement, or decisive date.
   string anchor_date = 4;
 
-  // Required. Profile whose custom exchange rate table is consulted before the
-  // ECB observations, so the preview matches what posting into that profile
-  // would do.
+  // Required. Profile whose rates apply. Only consulted when use_custom_rate is
+  // set, but always required so a preview names the books it describes.
   string profile_name = 5;
+
+  // Preview the profile's own rate for the publication date rather than the ECB
+  // reference rate. Must match what the posting will ask for, or the preview
+  // describes a conversion that will not happen.
+  bool use_custom_rate = 6;
 }
 
 // The conversion and immutable local ECB observation that would be used now.