diff --git a/changelog.d/7039-codegen-determinism.md b/changelog.d/7039-codegen-determinism.md
new file mode 100644
index 0000000000..2f6281e227
--- /dev/null
+++ b/changelog.d/7039-codegen-determinism.md
@@ -0,0 +1,13 @@
+Fixed non-deterministic LLVM IR: `emit_artifacts` iterated `hir.closure_source_text`
+(a `HashMap`) when emitting retained closure-source constants, so the `@.str.N`
+numbering of those constants was a per-process permutation — the same input
+compiled to different IR on every run.
+
+This was not cosmetic. It silently invalidates any A/B comparison of raw LLVM IR,
+a technique several representation-selection and GC investigations relied on for
+evidence. PR #7037 hit it directly: its first proof that `--opt-report` was
+observational passed on nondeterministic output and had to be redone with four
+runs per arm and a normalizer.
+
+Measured over 6 compiles of one file (md5 of the concatenated per-module `.ll`):
+5 distinct hashes before, 1 after. Emission order is the only thing that changes.
diff --git a/crates/perry-codegen/src/codegen/artifacts.rs b/crates/perry-codegen/src/codegen/artifacts.rs
index 015fadd153..865230483c 100644
--- a/crates/perry-codegen/src/codegen/artifacts.rs
+++ b/crates/perry-codegen/src/codegen/artifacts.rs
@@ -1858,10 +1858,23 @@ pub(super) fn emit_module_artifacts(c: ModuleArtifactsCtx<'_>) -> Result<()> {
             }
         }
     }
-    for (func_id, src) in &hir.closure_source_text {
-        if registered_fn_ids.contains(func_id) || !materialized_closure_ids.contains(func_id) {
-            continue;
-        }
+    // Sorted, NOT raw `HashMap` iteration (#7038). The loop above walks
+    // `hir.functions` (a `Vec`) and is already deterministic; this one keyed off
+    // the map's iteration order, so the `@.str.N` numbering of the emitted
+    // string constants was a per-process permutation. Same input, different
+    // `.ll` on every run — which silently invalidates any A/B that compares raw
+    // IR, a technique several representation and GC investigations relied on.
+    // Emission order is the only thing that changes; sorting by `FuncId` makes
+    // it stable without altering what is emitted.
+    let mut materialized_closure_sources: Vec<(&perry_hir::types::FuncId, &String)> = hir
+        .closure_source_text
+        .iter()
+        .filter(|(func_id, _)| {
+            !registered_fn_ids.contains(*func_id) && materialized_closure_ids.contains(*func_id)
+        })
+        .collect();
+    materialized_closure_sources.sort_by_key(|(func_id, _)| **func_id);
+    for (func_id, src) in materialized_closure_sources {
         let sym = format!("perry_closure_{}__{}", module_prefix, func_id);
         user_fn_source.push((sym, src.clone()));
     }