diff --git a/codegraph-kernel/src/resolve/mod.rs b/codegraph-kernel/src/resolve/mod.rs
index f00a04b89..fb8401a6b 100644
--- a/codegraph-kernel/src/resolve/mod.rs
+++ b/codegraph-kernel/src/resolve/mod.rs
@@ -706,6 +706,11 @@ pub struct KernelResolver {
     ts_imported_type_memo: HashMap<(String, String), Option<String>>,
     /// `(package, type)` → the project file declaring the package with that type in it.
     ts_ambient_memo: HashMap<(String, String), Option<String>>,
+    /// `file` → its ambient/global scope scan (None when unreadable). The
+    /// scan parses the file and ambient-module lookup walks every `.d.ts`
+    /// once per import, so each file is scanned once and shared — upstream
+    /// memoizes the same way (TS_GLOBAL_SCOPES).
+    ts_scope_memo: HashMap<String, Option<Rc<ts_known::TsScopeScan>>>,
     /// `(file, type as written)` → what the name names there.
     ts_named_type_memo: HashMap<(String, String), ts_known::TsNamedType>,
     /// Whether the project declares a `createInstance` returning an `InstanceType` of its constructor argument.
@@ -935,6 +940,7 @@ impl KernelResolver {
             ts_field_reading: HashSet::new(),
             ts_imported_type_memo: HashMap::new(),
             ts_ambient_memo: HashMap::new(),
+            ts_scope_memo: HashMap::new(),
             ts_named_type_memo: HashMap::new(),
             ts_create_instance_declared: None,
             python_bound_memo: HashMap::new(),
diff --git a/codegraph-kernel/src/resolve/ts_known.rs b/codegraph-kernel/src/resolve/ts_known.rs
index a6cd234f0..92a257447 100644
--- a/codegraph-kernel/src/resolve/ts_known.rs
+++ b/codegraph-kernel/src/resolve/ts_known.rs
@@ -489,7 +489,16 @@ pub(super) struct TsScopeScan {
 }
 
 impl KernelResolver {
-    pub(super) fn ts_scope_scan(&mut self, file: &str, r: &ResolveRefIn) -> Option<TsScopeScan> {
+    pub(super) fn ts_scope_scan(&mut self, file: &str, r: &ResolveRefIn) -> Option<Rc<TsScopeScan>> {
+        if let Some(memo) = self.ts_scope_memo.get(file) {
+            return memo.clone();
+        }
+        let scan = self.ts_scope_scan_uncached(file, r).map(Rc::new);
+        self.ts_scope_memo.insert(file.to_string(), scan.clone());
+        scan
+    }
+
+    fn ts_scope_scan_uncached(&mut self, file: &str, r: &ResolveRefIn) -> Option<TsScopeScan> {
         let source = self.read_file(file)?;
         let mut site = r.clone(); site.file_path = file.to_string(); site.language = "typescript".to_string();
         let tree = self.js_binding_tree(&source, &site)?;