Ask squeue for the single purpose reason code

CHANGELOG.md

@@ -7,6 +7,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Fixed
+
+- The `Reason` column asks `squeue` for `%r` rather than the dual-purpose `%R`, which returns the allocated nodes for anything that is not pending or failed. It now says why a job is in its current state instead of repeating the `Node` column on every running row, sorting by it sorts by the reason, and a job with no reason shows the usual `-` instead of `None`.
+
 ## [0.2.0] - 2026-08-28
 
 ### Added

src/backend/query.rs

@@ -192,7 +192,11 @@ pub fn decode_squeue_output(raw: &str, fmt: &str) -> Vec<Job> {
                 "%V" => job.submit_time = Some(val),
                 "%S" => job.start_time = Some(val),
                 "%e" => job.end_time = Some(val),
-                "%R" => job.reason = Some(val),
+                // squeue prints "None" when a job has no reason, which the
+                // table shows as the same "-" placeholder as any other unset
+                // cell. %R is deliberately not accepted here: it returns the
+                // nodelist for anything that is not pending or failed.
+                "%r" => job.reason = (val != "None").then_some(val),
                 _ => {}
             }
         }

src/views/fields.rs

@@ -74,7 +74,7 @@ impl JobField {
             JobField::SubmitTime => "%V",
             JobField::StartTime => "%S",
             JobField::EndTime => "%e",
-            JobField::PendReason => "%R",
+            JobField::PendReason => "%r",
         }
     }
 

tests/parsing.rs

@@ -59,7 +59,7 @@ fn blank_lines_are_skipped() {
 }
 
 /// Every column the UI can request must decode into a field; otherwise the
-/// column silently renders empty (the bug the `%R` column once had).
+/// column silently renders empty.
 #[test]
 fn every_field_code_is_decoded() {
     for field in JobField::enumerate() {
@@ -77,3 +77,26 @@ fn every_field_code_is_decoded() {
         );
     }
 }
+
+/// `%R` is dual purpose: for a running job it returns the allocated nodes,
+/// so a Reason column built on it just repeats the Node column.
+#[test]
+fn the_reason_column_asks_for_the_single_purpose_code() {
+    assert_eq!(JobField::PendReason.format_code(), "%r");
+}
+
+#[test]
+fn reason_decodes_for_a_pending_job() {
+    let raw = line(&["1002", "N/A", "Priority"]);
+    let jobs = decode_squeue_output(&raw, &["%i", "%N", "%r"].join(FIELD_SEP));
+    assert_eq!(jobs[0].reason.as_deref(), Some("Priority"));
+}
+
+/// `squeue` writes "None" rather than an empty cell for a job with no reason,
+/// and the table shows an unset reason as the same "-" as any other blank.
+#[test]
+fn a_reason_of_none_reads_as_unset() {
+    let raw = line(&["1001", "None"]);
+    let jobs = decode_squeue_output(&raw, &["%i", "%r"].join(FIELD_SEP));
+    assert_eq!(jobs[0].reason, None);
+}