Add R backend-controlled format options to data explorer

crates/amalthea/src/comm/data_explorer_comm.rs

@@ -92,9 +92,12 @@ pub struct BackendState {
 	/// requests. This parameter may change.
 	pub connected: Option<bool>,
 
-	/// Optional experimental parameter to provide an explanation when
-	/// connected=false. This parameter may change.
-	pub error_message: Option<String>
+    /// Optional experimental parameter to provide an explanation when
+    /// connected=false. This parameter may change.
+    pub error_message: Option<String>,
+
+    /// Optional formatting options for frontend display
+    pub format_options: Option<FormatOptions>,
 }
 
 /// Schema for a column in a table

crates/ark/src/data_explorer/r_data_explorer.rs

@@ -72,6 +72,7 @@ use crossbeam::channel::Sender;
 use crossbeam::select;
 use harp::exec::RFunction;
 use harp::exec::RFunctionExt;
+use harp::get_option;
 use harp::object::RObject;
 use harp::r_symbol;
 use harp::table_kind;
@@ -1159,6 +1160,7 @@ impl RDataExplorer {
                     }]),
                 },
             },
+            format_options: Some(Self::current_format_options()),
         };
         Ok(DataExplorerBackendReply::GetStateReply(state))
     }
@@ -1299,6 +1301,18 @@ impl RDataExplorer {
         // Call the conversion function with resolved sort keys
         convert_to_code::convert_to_code(params, object_name, &resolved_sort_keys)
     }
+
+    fn current_format_options() -> FormatOptions {
+        let scipen: i64 = get_option("scipen").try_into().unwrap_or(0);
+        let max_integral_digits = (7 + scipen).clamp(1, 20);
+        FormatOptions {
+            large_num_digits: 2,
+            small_num_digits: 4,
+            max_integral_digits,
+            max_value_length: 1000,
+            thousands_sep: None,
+        }
+    }
 }
 
 /// Open an R object in the data viewer.