diff --git a/server-rs/crates/platform-image/src/pixel_art_snapper.rs b/server-rs/crates/platform-image/src/pixel_art_snapper.rs
index e22f63c22..cca5e58a2 100644
--- a/server-rs/crates/platform-image/src/pixel_art_snapper.rs
+++ b/server-rs/crates/platform-image/src/pixel_art_snapper.rs
@@ -588,10 +588,18 @@ fn estimate_step_size(profile: &[f64], config: SnapConfig) -> Option<f64> {
         return None;
     }
     let threshold = maximum * config.peak_threshold_multiplier;
+    // The profile is a two-span central difference, so a hard block edge between
+    // columns `b - 1` and `b` makes `profile[b - 1]` and `profile[b]` bitwise equal:
+    // both straddle the same edge and sum the same per-row terms in the same order.
+    // A strict comparison on both sides rejects both ends of that plateau, which is
+    // why perfectly snapped pixel art used to yield zero peaks. Accepting equality on
+    // the left keeps exactly one index per plateau — the right end, which is the real
+    // boundary — while a strict comparison on the right still rejects the interior of
+    // wider constant runs.
     let peaks = (1..profile.len().saturating_sub(1))
         .filter(|&index| {
             profile[index] > threshold
-                && profile[index] > profile[index - 1]
+                && profile[index] >= profile[index - 1]
                 && profile[index] > profile[index + 1]
         })
         .collect::<Vec<_>>();
@@ -694,7 +702,10 @@ fn walk(
         let mut best_index = start;
         let mut best_value = -1.0f64;
         for (index, value) in profile.iter().enumerate().take(end).skip(start) {
-            if *value > best_value {
+            // `>=` keeps the last index of an equal run, matching the plateau end that
+            // `estimate_step_size` selects. Picking the first index instead would place
+            // every cut one pixel left of the real block boundary.
+            if *value >= best_value {
                 best_value = *value;
                 best_index = index;
             }
@@ -878,7 +889,8 @@ fn snap_uniform_cuts(
             .take(end.min(profile.len().saturating_sub(1)) + 1)
             .skip(start)
         {
-            if *value > best_value {
+            // Same plateau-end convention as `walk`.
+            if *value >= best_value {
                 best_value = *value;
                 best_index = index;
             }