diff --git a/src/openhuman/memory_sync/composio/providers/github/provider.rs b/src/openhuman/memory_sync/composio/providers/github/provider.rs
index e69328f1e..e07c86924 100644
--- a/src/openhuman/memory_sync/composio/providers/github/provider.rs
+++ b/src/openhuman/memory_sync/composio/providers/github/provider.rs
@@ -197,12 +197,7 @@ impl ComposioProvider for GitHubProvider {
         };
 
         // Build the base search query.
-        let query = match &state.cursor {
-            Some(cursor) => {
-                format!("involves:{login} updated:>{cursor}")
-            }
-            None => format!("involves:{login}"),
-        };
+        let query = build_search_query(&login, state.cursor.as_deref());
 
         let mut total_fetched: usize = 0;
         let mut total_persisted: usize = 0;
@@ -423,3 +418,21 @@ impl GitHubProvider {
         })
     }
 }
+
+/// Build the GitHub Search-Issues query for an incremental sync.
+///
+/// `involves:` is GitHub's logical-OR over `author`, `assignee`, `mentions`,
+/// and `commenter`, so the result set covers every item the connected user
+/// has standing in — not only items explicitly assigned to them. When a
+/// cursor from a prior sync is present, an `updated:>{cursor}` clause is
+/// appended so the next page request only returns items changed since.
+///
+/// Kept as a free function (rather than inline in `sync()`) so the query
+/// contract — specifically the `involves:` qualifier — can be asserted by
+/// unit tests without spinning up the full sync pipeline.
+pub(super) fn build_search_query(login: &str, cursor: Option<&str>) -> String {
+    match cursor {
+        Some(cursor) => format!("involves:{login} updated:>{cursor}"),
+        None => format!("involves:{login}"),
+    }
+}
diff --git a/src/openhuman/memory_sync/composio/providers/github/tests.rs b/src/openhuman/memory_sync/composio/providers/github/tests.rs
index 7dafed462..32cceadfd 100644
--- a/src/openhuman/memory_sync/composio/providers/github/tests.rs
+++ b/src/openhuman/memory_sync/composio/providers/github/tests.rs
@@ -1,5 +1,6 @@
 //! Unit tests for the GitHub Composio provider.
 
+use super::provider::build_search_query;
 use super::sync::{
     extract_issue_id, extract_issue_title, extract_issue_updated_at, extract_issues,
     extract_user_login,
@@ -179,3 +180,45 @@ fn default_impl_matches_new() {
         b.curated_tools().map(<[_]>::len),
     );
 }
+
+// ── build_search_query ──────────────────────────────────────────────────────
+//
+// Regression coverage for #2418: the GitHub Memory Provider must scope the
+// periodic sync to `involves:{login}` — GitHub's logical-OR over `author`,
+// `assignee`, `mentions`, and `commenter` — rather than the narrower
+// `assignee:{login}`. Without these assertions the qualifier could silently
+// regress to assignee-only and lose author / mention / commenter coverage
+// for OSS contributors who are rarely explicitly assigned.
+
+#[test]
+fn build_search_query_uses_involves_qualifier_without_cursor() {
+    let query = build_search_query("octocat", None);
+    assert_eq!(query, "involves:octocat");
+}
+
+#[test]
+fn build_search_query_does_not_fall_back_to_assignee_qualifier() {
+    let query = build_search_query("octocat", None);
+    assert!(
+        !query.contains("assignee:"),
+        "query must not use the narrower assignee-only qualifier (see #2418): {query}"
+    );
+    assert!(query.starts_with("involves:"));
+}
+
+#[test]
+fn build_search_query_appends_updated_clause_when_cursor_present() {
+    let query = build_search_query("octocat", Some("2026-05-25T00:00:00Z"));
+    assert_eq!(
+        query,
+        "involves:octocat updated:>2026-05-25T00:00:00Z",
+        "cursor must be threaded through as an updated:> clause so incremental syncs only refetch changed items"
+    );
+}
+
+#[test]
+fn build_search_query_interpolates_login_verbatim() {
+    let query = build_search_query("Hyphen-User_99", Some("2026-01-02T03:04:05Z"));
+    assert!(query.contains("involves:Hyphen-User_99"));
+    assert!(query.contains("updated:>2026-01-02T03:04:05Z"));
+}