fix(hir): preserve shared cells in class capture refresh

changelog.d/8896-class-capture-refresh.md

@@ -0,0 +1,3 @@
+Preserve shared mutable capture cells when refreshing per-evaluation class
+expressions, restoring dynamic construction when a fresh class captures an
+assigned dependency through its heritage or members.

crates/perry-hir/src/lower/shared_mutable_capture.rs

@@ -967,6 +967,27 @@ fn rewrite_expr(expr: &mut Expr, shared: &HashSet<LocalId>, index_uses: &HashSet
         // Capture sites snapshot the WHOLE handle (the array). Leave the bare
         // `LocalGet(id)` capture args alone; still rewrite non-capture children.
         Expr::RegisterClassCaptures { .. } => return,
+        // Release follow-up: the end-of-body refresh for a fresh class
+        // object carries the same capture-param-ordered handles as the initial
+        // `ClassExprFresh` snapshot. A shared-mutable capture is a one-element
+        // array cell, so refreshing with `id[0]` replaces the cell with its
+        // current scalar value. The constructor still treats the refreshed
+        // slot as a cell and reads `[0]`, producing `undefined`. Preserve bare
+        // shared-cell handles in `captures`, while still rewriting the owner
+        // expression and any non-capture children normally.
+        Expr::RefreshClassExprCaptures {
+            class_value,
+            captures,
+        } => {
+            rewrite_expr(class_value, shared, index_uses);
+            for capture in captures.iter_mut() {
+                if matches!(capture, Expr::LocalGet(id) if index_uses.contains(id)) {
+                    continue;
+                }
+                rewrite_expr(capture, shared, index_uses);
+            }
+            return;
+        }
         // #6497: the per-evaluation fresh-binding path (#6470) carries the
         // same capture-param-ordered `LocalGet` args as RegisterClassCaptures
         // — they too must snapshot the WHOLE box handle. Rewriting them to

crates/perry-hir/src/lower/tests.rs

@@ -1187,6 +1187,50 @@ fn fresh_class_declaration_collision_keeps_lexical_binding() {
     }));
 }
 
+/// A fresh class's end-of-body capture refresh must preserve the whole
+/// one-element shared-mutable cell, matching the initial `ClassExprFresh`
+/// snapshot. Refreshing with `cell[0]` stores the scalar value, while lifted
+/// members still read the constructor capture as `capture[0]`.
+#[test]
+fn fresh_class_refresh_keeps_shared_capture_cell_handle() {
+    let source = r#"
+        const exported = (() => {
+            let dep;
+            dep = { default: "ok" };
+            const holder = {};
+            holder.default = class {
+                read() { return dep.default; }
+            };
+            return holder.default;
+        })();
+    "#;
+    let module = perry_parser::parse_typescript(source, "t.ts").expect("source parses");
+    let hir = super::lower_module(&module, "t", "t.ts").expect("source lowers");
+    let compact: String = format!("{:#?}", hir.init)
+        .chars()
+        .filter(|ch| !ch.is_whitespace())
+        .collect();
+
+    let mut remainder = compact.as_str();
+    let mut refreshes = 0usize;
+    while let Some(offset) = remainder.find("RefreshClassExprCaptures{") {
+        remainder = &remainder[offset + "RefreshClassExprCaptures{".len()..];
+        let captures = remainder
+            .find("captures:[")
+            .map(|index| &remainder[index + "captures:[".len()..])
+            .expect("refresh includes a captures vector");
+        assert!(
+            captures.starts_with("LocalGet("),
+            "fresh-class refresh must carry the shared cell handle, not an indexed value: {captures}"
+        );
+        refreshes += 1;
+    }
+    assert!(
+        refreshes > 0,
+        "fixture must emit at least one fresh-class refresh"
+    );
+}
+
 /// Companion (the case the depth rule must NOT break): a module-scope `class e`
 /// and a factory-local `let e` holding a different constructor. JS says the
 /// nearer local wins, so `new e()` inside the factory must still construct the