diff --git a/src/memory/retrieval/fast.rs b/src/memory/retrieval/fast.rs
index 2322b9a..318552e 100644
--- a/src/memory/retrieval/fast.rs
+++ b/src/memory/retrieval/fast.rs
@@ -208,7 +208,7 @@ fn resolve_local(
     let mut hits = Vec::new();
     for (id, _) in ordered {
         if let Some(mut hit) = by_id.remove(&id) {
-            if source_scope.is_some_and(|scope| !scope.contains(&hit.tree_scope)) {
+            if source_scope.is_some_and(|scope| !source_scope_allows(scope, &hit.tree_scope)) {
                 continue;
             }
             hit.score = coverage.get(&id).copied().unwrap_or_default();
@@ -239,7 +239,9 @@ async fn dense(
     )
     .await?;
     if let Some(scope) = source_scope {
-        response.hits.retain(|hit| scope.contains(&hit.tree_scope));
+        response
+            .hits
+            .retain(|hit| source_scope_allows(scope, &hit.tree_scope));
     }
     let total = response.hits.len();
     response.hits.truncate(limit);
@@ -282,6 +284,19 @@ fn dedup_ids(ids: impl Iterator<Item = String>) -> Vec<String> {
     ids.filter(|id| seen.insert(id.clone())).collect()
 }
 
+fn source_scope_allows(scope: &HashSet<String>, tree_scope: &str) -> bool {
+    if scope.contains(tree_scope) {
+        return true;
+    }
+    extract_mem_src_id(tree_scope).is_some_and(|id| scope.contains(id))
+}
+
+fn extract_mem_src_id(value: &str) -> Option<&str> {
+    let rest = value.strip_prefix("mem_src:")?;
+    let (id, _) = rest.split_once(':')?;
+    (!id.is_empty()).then_some(id)
+}
+
 #[cfg(test)]
 #[path = "fast_tests.rs"]
 mod tests;
diff --git a/src/memory/retrieval/source.rs b/src/memory/retrieval/source.rs
index fffeb78..077f00f 100644
--- a/src/memory/retrieval/source.rs
+++ b/src/memory/retrieval/source.rs
@@ -236,6 +236,9 @@ fn scope_matches_kind(scope: &str, kind_prefix: &str) -> bool {
     if lower.starts_with(&format!("{kind_prefix}:")) {
         return true;
     }
+    if kind_prefix == SourceKind::Document.as_str() && lower.starts_with("mem_src:") {
+        return true;
+    }
     PLATFORM_KINDS
         .iter()
         .any(|(platform, kind)| *kind == kind_prefix && lower.starts_with(&format!("{platform}:")))
diff --git a/src/memory/retrieval/source_tests.rs b/src/memory/retrieval/source_tests.rs
index 343aded..b8d0e3d 100644
--- a/src/memory/retrieval/source_tests.rs
+++ b/src/memory/retrieval/source_tests.rs
@@ -195,6 +195,10 @@ fn scope_prefix_matching_known_platforms() {
     assert!(scope_matches_kind("gmail:alice", "email"));
     assert!(scope_matches_kind("notion:page123", "document"));
     assert!(scope_matches_kind("linear:conn-1:issue-abc", "document"));
+    assert!(scope_matches_kind(
+        "mem_src:src-folder-9:Slides_Notes/example.md",
+        "document"
+    ));
     assert!(!scope_matches_kind("slack:#eng", "email"));
     assert!(scope_matches_kind("chat:custom", "chat"));
 }