diff --git a/crdt-sync/crdt_sync/tests/test_tool_seed_session_main.py b/crdt-sync/crdt_sync/tests/test_tool_seed_session_main.py
index 9b6360d..b3e5bfe 100644
--- a/crdt-sync/crdt_sync/tests/test_tool_seed_session_main.py
+++ b/crdt-sync/crdt_sync/tests/test_tool_seed_session_main.py
@@ -59,6 +59,25 @@ def test_home_guard_is_among_the_default_apps() -> None:
     assert "home_guard" in ss.DEFAULT_APPS
 
 
+def test_sufler_is_among_the_default_apps() -> None:
+    """Its PC TTS relay (``sufler_tts.relay.setup``) reads
+    ``~/.config/sufler/firebase_auth.json`` via ``credential_store_for``."""
+    assert "sufler" in ss.DEFAULT_APPS
+
+
+def test_the_app_flag_accepts_sufler() -> None:
+    """``--app sufler`` must parse (argparse choices come from DEFAULT_APPS)."""
+    with (
+        patch.object(ss.FirebaseConfig, "load", return_value=_CONFIG),
+        patch.object(git, "fetch_id_token", return_value=_ID_VALUE),
+        patch.object(ss, "seed_apps", return_value=["sufler"]) as seeded,
+    ):
+        code = ss.main([*_ARGV, "--app", "sufler"])
+
+    assert code == 0
+    assert seeded.call_args.args[2] == ("sufler",)
+
+
 def test_a_single_app_can_be_selected() -> None:
     """--app narrows the run, which is what a rerun after a failure uses."""
     with (
diff --git a/crdt-sync/tool/_seeded_apps.py b/crdt-sync/tool/_seeded_apps.py
index c0ffa04..450243e 100644
--- a/crdt-sync/tool/_seeded_apps.py
+++ b/crdt-sync/tool/_seeded_apps.py
@@ -55,4 +55,8 @@ DEFAULT_APPS: Final = (
     # ~/src/tutor: its PC worker answers the Flutter client's requests over
     # RTDB (/tutor/v1), headless, with a session of its own.
     "tutor",
+    # ~/src/sufler: its PC TTS relay (tts/sufler_tts/relay/setup.py) answers
+    # the Flutter client over RTDB (/sufler), headless, reading
+    # ~/.config/sufler/firebase_auth.json via credential_store_for("sufler").
+    "sufler",
 )