diff --git a/crates/omnigraph/src/loader/mod.rs b/crates/omnigraph/src/loader/mod.rs
index 6152072..a7aae28 100644
--- a/crates/omnigraph/src/loader/mod.rs
+++ b/crates/omnigraph/src/loader/mod.rs
@@ -1463,8 +1463,9 @@ pub(crate) fn enforce_unique_constraints_intra_batch(
             if any_null {
                 continue;
             }
-            // Unit separator (U+001F) keeps composite parts unambiguous; it
-            // cannot appear in the scalar renderings of supported types.
+            // Join on the unit separator (U+001F) — a control char highly
+            // unlikely to occur in real data, keeping composite keys
+            // effectively unambiguous (cf. `exec/merge.rs`, which uses `|`).
             let value = parts.join("\u{1f}");
             if let Some(prev_row) = seen.insert(value.clone(), row) {
                 return Err(OmniError::manifest(format!(