Util for getting active request (#1110)

I'm preparing to do some work to add more metadata to the execute
request, and am adding this to make it easy to inspect it.

<img width="809" height="737" alt="image"
src="https://github.com/user-attachments/assets/bea0ff60-6b92-4e55-99ab-fd5bb8a1f2fa"
/>

Author: jmcphers

crates/ark/src/console/console_repl.rs

@@ -721,6 +721,11 @@ impl Console {
         }
     }
 
+    /// Get the active execute request, if any.
+    pub(crate) fn get_active_execute_request(&self) -> Option<&ExecuteRequest> {
+        self.active_request.as_ref().map(|req| &req.request)
+    }
+
     /// Get the current execution context if an active request exists.
     /// Returns (execution_id, code) tuple where execution_id is the Jupyter message ID.
     pub(crate) fn get_execution_context(&self) -> Option<(String, String)> {
@@ -2790,3 +2795,16 @@ unsafe extern "C-unwind" fn ps_get_virtual_document(uri: SEXP) -> anyhow::Result
         None => Ok(RObject::null().sexp),
     }
 }
+
+/// Returns the currently active execute request as an R named list,
+/// or NULL if no execute request is in flight.
+#[harp::register]
+pub unsafe extern "C-unwind" fn ps_get_active_request() -> anyhow::Result<SEXP> {
+    let Some(req) = Console::get().get_active_execute_request() else {
+        return Ok(libr::R_NilValue);
+    };
+
+    let json = serde_json::to_value(req)?;
+    let r_obj = RObject::try_from(json)?;
+    Ok(r_obj.sexp)
+}

crates/ark/src/modules/positron/utils.R

@@ -56,6 +56,14 @@
     ark_version
 }
 
+# Return the active (in flight) execute_request data structure; useful for
+# inspecting what metadata has been sent from the front end.
+#
+# Internal utility; invoke with: `.ps.internal(active_request())`
+active_request <- function() {
+    .ps.Call("ps_get_active_request")
+}
+
 # Sleep that doesn't check for interrupts to test an unresponsive runtime.
 #' @export
 .ps.deep_sleep <- function(secs) {