diff --git a/TESTING.md b/TESTING.md
index d961a96..a28c919 100644
--- a/TESTING.md
+++ b/TESTING.md
@@ -8,7 +8,7 @@
 > Prerequisites: SSH tunnel is active on port 8787. Open http://localhost:8787 in browser.
 > Server health check: curl http://127.0.0.1:8787/health should return {"status":"ok"}.
 >
-> Automated coverage: 1353 tests collected via `pytest tests/ --collect-only -q`. Includes onboarding coverage for bootstrap/static wizard presence, real provider config persistence (`config.yaml` + `.env`), the `/api/onboarding/*` backend, the onboarding skip/existing-config guard, and CSS regression coverage for smooth thinking/tool card disclosure animation.
+> Automated coverage: 1578 tests collected via `pytest tests/ --collect-only -q`. Includes onboarding coverage for bootstrap/static wizard presence, real provider config persistence (`config.yaml` + `.env`), the `/api/onboarding/*` backend, the onboarding skip/existing-config guard, and CSS regression coverage for smooth thinking/tool card disclosure animation.
 > Run: `pytest tests/ -v --timeout=60`
 >
 > Local regression focus: verify that a previously closed workspace panel stays visually closed from first paint through boot completion on desktop refresh; there should be no brief open-then-close flash.
diff --git a/tests/_pytest_port.py b/tests/_pytest_port.py
index 19afc6a..ce687b3 100644
--- a/tests/_pytest_port.py
+++ b/tests/_pytest_port.py
@@ -40,3 +40,7 @@ TEST_STATE_DIR = pathlib.Path(os.environ.get(
     'HERMES_WEBUI_TEST_STATE_DIR',
     str(_HERMES_HOME / _auto_state_dir_name(_REPO_ROOT))
 ))
+
+# Default model injected by conftest — tests that mutate the default model
+# must restore to this value so later tests see a consistent baseline.
+TEST_DEFAULT_MODEL = os.environ.get('HERMES_WEBUI_DEFAULT_MODEL', 'openai/gpt-5.4-mini')
diff --git a/tests/test_sprint12.py b/tests/test_sprint12.py
index 7e3ec0a..25e5560 100644
--- a/tests/test_sprint12.py
+++ b/tests/test_sprint12.py
@@ -3,7 +3,7 @@ Sprint 12 Tests: settings panel, session pinning, session import, SSE reconnect.
 """
 import json, pathlib, urllib.error, urllib.request, urllib.parse
 
-from tests._pytest_port import BASE
+from tests._pytest_port import BASE, TEST_DEFAULT_MODEL
 
 
 def get(path):
@@ -40,8 +40,6 @@ def test_settings_get_returns_defaults():
 
 def test_default_model_updates_hermes_config():
     """POST /api/default-model updates the effective Hermes default model."""
-    original, _ = get("/api/models")
-    original_model = original.get("default_model") or ""
     try:
         d, status = post("/api/default-model", {"model": "anthropic/claude-sonnet-4.6"})
         assert status == 200
@@ -50,9 +48,9 @@ def test_default_model_updates_hermes_config():
         # Both should resolve to the same model (may differ in prefix normalization)
         assert 'claude-sonnet-4.6' in d2['default_model']
     finally:
-        # Always restore — regardless of test ordering or failures
-        if original_model:
-            post("/api/default-model", {"model": original_model})
+        # Always restore to the conftest-injected default so later tests see
+        # a consistent baseline regardless of test ordering.
+        post("/api/default-model", {"model": TEST_DEFAULT_MODEL})
 
 
 def test_settings_does_not_persist_default_model():