diff --git a/gateway/whatsapp_identity.py b/gateway/whatsapp_identity.py
index 7a0efe4e9f9..19fade10b4e 100644
--- a/gateway/whatsapp_identity.py
+++ b/gateway/whatsapp_identity.py
@@ -42,7 +42,7 @@ logger = logging.getLogger(__name__)
 # full-width digits / Unicode word chars can't sneak through.
 _SAFE_IDENTIFIER_RE = re.compile(r"^[A-Za-z0-9@.+\-]+$")
 
-from hermes_constants import get_hermes_home
+from hermes_constants import get_hermes_dir
 
 
 def normalize_whatsapp_identifier(value: str) -> str:
@@ -133,7 +133,7 @@ def expand_whatsapp_aliases(identifier: str) -> Set[str]:
     if not normalized:
         return set()
 
-    session_dir = get_hermes_home() / "whatsapp" / "session"
+    session_dir = get_hermes_dir("platforms/whatsapp/session", "whatsapp/session")
     resolved: Set[str] = set()
     queue = [normalized]
 
diff --git a/tests/gateway/test_whatsapp_identity.py b/tests/gateway/test_whatsapp_identity.py
new file mode 100644
index 00000000000..6fa6f840364
--- /dev/null
+++ b/tests/gateway/test_whatsapp_identity.py
@@ -0,0 +1,37 @@
+"""Tests for gateway.whatsapp_identity alias resolution path."""
+
+import json
+
+from gateway.whatsapp_identity import expand_whatsapp_aliases
+
+
+def test_aliases_resolve_on_modern_platforms_layout(tmp_path, monkeypatch):
+    tmp_home = tmp_path / "hermes-home"
+    mapping_dir = tmp_home / "platforms" / "whatsapp" / "session"
+    mapping_dir.mkdir(parents=True, exist_ok=True)
+    (mapping_dir / "lid-mapping-999999999999999.json").write_text(
+        json.dumps("15551234567@s.whatsapp.net"),
+        encoding="utf-8",
+    )
+    monkeypatch.setenv("HERMES_HOME", str(tmp_home))
+
+    assert expand_whatsapp_aliases("999999999999999@lid") == {
+        "999999999999999",
+        "15551234567",
+    }
+
+
+def test_aliases_resolve_on_legacy_layout(tmp_path, monkeypatch):
+    tmp_home = tmp_path / "hermes-home"
+    mapping_dir = tmp_home / "whatsapp" / "session"
+    mapping_dir.mkdir(parents=True, exist_ok=True)
+    (mapping_dir / "lid-mapping-999999999999999.json").write_text(
+        json.dumps("15551234567@s.whatsapp.net"),
+        encoding="utf-8",
+    )
+    monkeypatch.setenv("HERMES_HOME", str(tmp_home))
+
+    assert expand_whatsapp_aliases("999999999999999@lid") == {
+        "999999999999999",
+        "15551234567",
+    }