From 44e9ddad45dae080d3eefaf878233b659d641ff2 Mon Sep 17 00:00:00 2001
From: prxnvt <53838599+prxnvt@users.noreply.github.com>
Date: Sun, 1 Nov 2026 12:33:22 -0500
Subject: [PATCH] Engine: a Python result cut by the adoption budget takes its
 cached spill with it

When a file's cached Python spills were larger than the adoption budget, the
cells past it kept only their own value, but their spill ranges and spilled
values stayed on the sheet, which went on showing values no result held. The
spill of such a cell is now cleared, as for a dropped result; the warning is
unchanged.
---
 crates/engine/src/io.rs                 |  5 ++++
 crates/engine/src/tests/python_files.rs | 34 +++++++++++++++++++++++++
 2 files changed, 39 insertions(+)

diff --git a/crates/engine/src/io.rs b/crates/engine/src/io.rs
index 2622f0ae8..7e8aa1da7 100644
--- a/crates/engine/src/io.rs
+++ b/crates/engine/src/io.rs
@@ -168,6 +168,11 @@ pub fn adopt_python(wb: &mut Workbook) -> Vec<String> {
         for (anchor, range) in spills {
             let Some(left) = budget.checked_sub(range.count()) else {
                 skipped += 1;
+                // The cell keeps only its own value, so its cached spill goes too: the sheet would
+                // otherwise show spilled values that no result holds.
+                if let Some(r) = sh.spill_ranges.remove(&anchor) {
+                    sh.clear_spill(r);
+                }
                 continue;
             };
             budget = left;
diff --git a/crates/engine/src/tests/python_files.rs b/crates/engine/src/tests/python_files.rs
index 00b597445..6870664f2 100644
--- a/crates/engine/src/tests/python_files.rs
+++ b/crates/engine/src/tests/python_files.rs
@@ -260,6 +260,40 @@ fn many_cells_naming_one_long_script_take_from_one_budget() {
     assert_eq!(sh.value(CellRef::parse("A20000").unwrap()), Value::Number(1.0), "the others keep their values");
 }
 
+#[test]
+fn a_result_cut_by_the_budget_takes_its_cached_spill_with_it() {
+    // Five Python cells each with a cached 1,000 x 1,000 spill: the budget rebuilds four results;
+    // the fifth cell keeps only its own value, and its spilled values no longer show.
+    let mut wb = Workbook::new();
+    let sh = wb.sheet_mut(0).unwrap();
+    for i in 0..5u32 {
+        let anchor = CellRef::new(0, i * 1_000);
+        sh.set_cell(anchor, Cell { py: Some(Arc::new(PyCode::new("x"))), ..Cell::value(Value::Number(1.0)) });
+        sh.spill_ranges.insert(anchor, RangeRef::new(anchor, CellRef::new(999, i * 1_000 + 999)));
+        sh.spill.insert(CellRef::new(1, i * 1_000), Value::Number(7.0));
+        sh.spill.insert(CellRef::new(999, i * 1_000 + 999), Value::Number(8.0));
+    }
+    let warnings = crate::io::adopt_python(&mut wb);
+    assert!(warnings.iter().any(|w| w.contains("Python")), "{warnings:?}");
+    let sh = wb.sheet(0).unwrap();
+    let mut cut = 0;
+    for i in 0..5u32 {
+        let anchor = CellRef::new(0, i * 1_000);
+        let rebuilt = sh.cell(anchor).and_then(|c| c.py.as_ref()).is_some_and(|p| p.output.is_some());
+        let (below, corner) = (sh.value(CellRef::new(1, i * 1_000)), sh.value(CellRef::new(999, i * 1_000 + 999)));
+        if rebuilt {
+            assert_eq!((below, corner), (Value::Number(7.0), Value::Number(8.0)), "a result within the budget keeps its spill");
+            assert!(sh.spill_ranges.contains_key(&anchor));
+        } else {
+            cut += 1;
+            assert_eq!((below, corner), (Value::Empty, Value::Empty), "no stale spilled values beyond the anchor");
+            assert!(!sh.spill_ranges.contains_key(&anchor));
+            assert_eq!(sh.value(anchor), Value::Number(1.0), "the cell keeps its own cached value");
+        }
+    }
+    assert_eq!(cut, 1);
+}
+
 #[test]
 fn native_json_keeps_python_cells_and_their_results() {
     let (mut s, long) = build();