diff --git a/crates/bgz-tensor/tests/palette_immutable_salience_probe.rs b/crates/bgz-tensor/tests/palette_immutable_salience_probe.rs
new file mode 100644
index 000000000..e345a957c
--- /dev/null
+++ b/crates/bgz-tensor/tests/palette_immutable_salience_probe.rs
@@ -0,0 +1,37 @@
+//! Read-only Palette256 frame and PCDVQ salience contract.
+//! This does not assert that dropping weak signals eliminates hallucinations.
+use bgz_tensor::{Base17, WeightPalette};
+
+fn axis(axis: usize, amplitude: i16) -> Base17 {
+    let mut dims = [0i16; 17];
+    dims[axis] = amplitude;
+    Base17 { dims }
+}
+
+#[test]
+fn directional_signal_has_higher_salience_than_same_amplitude_detail() {
+    let origin = axis(0, 0);
+    let directional = axis(0, 8);
+    let detail = axis(16, 8);
+    assert_eq!(origin.l1(&directional), origin.l1(&detail));
+    assert_eq!(origin.l1_weighted(&directional), 20 * 8);
+    assert_eq!(origin.l1_weighted(&detail), 8);
+}
+
+#[test]
+fn inference_reads_do_not_retrain_the_baked_reference() {
+    let rows = [axis(0, 0), axis(0, 12), axis(16, 2), axis(0, -12)];
+    let palette = WeightPalette::build(&rows, 3);
+    let original_entries = palette.entries.clone();
+    let original_radii = palette.radii.clone();
+    let original_counts = palette.counts.clone();
+    for _ in 0..64 {
+        for row in &rows {
+            let assignment = palette.assign(row);
+            assert!((assignment.index as usize) < palette.len());
+        }
+    }
+    assert_eq!(palette.entries, original_entries);
+    assert_eq!(palette.radii, original_radii);
+    assert_eq!(palette.counts, original_counts);
+}