diff --git a/molecule_agent/client.py b/molecule_agent/client.py
index d198215..f4f0713 100644
--- a/molecule_agent/client.py
+++ b/molecule_agent/client.py
@@ -498,6 +498,7 @@ class RemoteAgentClient:
         reported = self.reported_url or "remote://no-inbound"
         resp = self._session.post(
             f"{self.platform_url}/registry/register",
+            headers=self._auth_headers(),
             json={
                 "id": self.workspace_id,
                 "url": reported,
@@ -1061,13 +1062,14 @@ class RemoteAgentClient:
         """
         key = idempotency_key if idempotency_key else make_idempotency_key(task)
         resp = self._session.post(
-            f"{self.platform_url}/workspaces/{target_id}/delegate",
+            f"{self.platform_url}/workspaces/{self.workspace_id}/delegate",
             headers={
                 **self._auth_headers(),
                 "X-Workspace-ID": self.workspace_id,
                 "Content-Type": "application/json",
             },
             json={
+                "target_id": target_id,
                 "task": task,
                 "idempotency_key": key,
             },
@@ -1305,4 +1307,3 @@ __all__ = [
     "verify_plugin_sha256",
     "make_idempotency_key",
 ]
-
diff --git a/tests/test_remote_agent.py b/tests/test_remote_agent.py
index 4abed2a..5f1bb35 100644
--- a/tests/test_remote_agent.py
+++ b/tests/test_remote_agent.py
@@ -117,6 +117,36 @@ def test_register_saves_token_when_issued(client: RemoteAgentClient):
     assert kwargs["json"]["agent_card"] == {"name": "test-agent"}
 
 
+def test_register_sends_saas_routing_headers(tmp_token_dir: Path):
+    session = MagicMock()
+    c = RemoteAgentClient(
+        workspace_id="ws-saas",
+        platform_url="https://tenant.example.com",
+        org_id="org-uuid-123",
+        origin="https://tenant.example.com",
+        token_dir=tmp_token_dir,
+        session=session,
+    )
+    session.post.return_value = FakeResponse(200, {"status": "registered"})
+
+    c.register()
+
+    kwargs = session.post.call_args[1]
+    assert kwargs["headers"]["X-Molecule-Org-Id"] == "org-uuid-123"
+    assert kwargs["headers"]["Origin"] == "https://tenant.example.com"
+    assert "Authorization" not in kwargs["headers"]
+
+
+def test_register_includes_cached_token_when_present(client: RemoteAgentClient):
+    client.save_token("cached-token")
+    client._session.post.return_value = FakeResponse(200, {"status": "registered"})
+
+    client.register()
+
+    kwargs = client._session.post.call_args[1]
+    assert kwargs["headers"]["Authorization"] == "Bearer cached-token"
+
+
 def test_register_keeps_cached_token_when_platform_omits(client: RemoteAgentClient):
     # Simulate re-register of an already-tokened workspace: platform returns
     # no auth_token, SDK must keep using the cached one.
@@ -773,7 +803,7 @@ from molecule_agent.client import make_idempotency_key, strip_a2a_boundary
 
 
 def test_delegate_posts_task_and_idempotency_key(client: RemoteAgentClient):
-    """delegate() sends task + auto-generated idempotency_key to /delegate."""
+    """delegate() sends source in URL and target_id in the body."""
     client.save_token("tok")
     client._session.post.return_value = FakeResponse(200, {"status": "ok"})
 
@@ -781,8 +811,9 @@ def test_delegate_posts_task_and_idempotency_key(client: RemoteAgentClient):
 
     assert result["status"] == "ok"
     url = client._session.post.call_args[0][0]
-    assert url == "http://platform.test/workspaces/peer-ws/delegate"
+    assert url == "http://platform.test/workspaces/ws-abc-123/delegate"
     body = client._session.post.call_args[1]["json"]
+    assert body["target_id"] == "peer-ws"
     assert body["task"] == "index the docs"
     assert body["idempotency_key"] is not None
     assert len(body["idempotency_key"]) == 64  # SHA-256 hex