fix(hermes_cli): keep TTS/setup xAI OAuth from switching active chat provider

Save side-tool OAuth tokens without promoting xai-oauth via active_provider
or model.provider so hermes setup tts login no longer hijacks inference routing.

tests/hermes_cli/test_auth_xai_oauth_provider.py

@@ -281,6 +281,40 @@ def test_save_and_read_xai_oauth_tokens_roundtrip(tmp_path, monkeypatch):
     assert data["discovery"]["token_endpoint"] == "https://auth.x.ai/oauth2/token"
 
 
+def test_save_xai_oauth_tokens_set_active_false_preserves_active_provider(
+    tmp_path, monkeypatch
+):
+    """Side-tool credential saves must not flip auth.json active_provider."""
+    hermes_home = tmp_path / "hermes"
+    hermes_home.mkdir(parents=True, exist_ok=True)
+    auth_path = hermes_home / "auth.json"
+    auth_path.write_text(
+        json.dumps(
+            {
+                "version": 1,
+                "active_provider": "openrouter",
+                "providers": {},
+            }
+        )
+    )
+    monkeypatch.setenv("HERMES_HOME", str(hermes_home))
+
+    _save_xai_oauth_tokens(
+        {
+            "access_token": "side-tool-at",
+            "refresh_token": "side-tool-rt",
+            "id_token": "",
+            "token_type": "Bearer",
+        },
+        discovery={"token_endpoint": "https://auth.x.ai/oauth2/token"},
+        set_active=False,
+    )
+
+    raw = json.loads(auth_path.read_text())
+    assert raw["active_provider"] == "openrouter"
+    assert raw["providers"]["xai-oauth"]["tokens"]["access_token"] == "side-tool-at"
+
+
 def test_read_xai_oauth_tokens_missing(tmp_path, monkeypatch):
     hermes_home = tmp_path / "hermes"
     hermes_home.mkdir(parents=True, exist_ok=True)

tests/hermes_cli/test_setup_tts_xai_oauth.py

@@ -0,0 +1,78 @@
+"""Regression: TTS/setup xAI OAuth must not hijack the active chat provider."""
+
+import json
+
+import yaml
+
+
+def test_run_xai_oauth_login_from_setup_does_not_hijack_active_provider(
+    tmp_path, monkeypatch
+):
+    """TTS/setup OAuth must save tokens without switching chat inference routing.
+
+    Regression: `_run_xai_oauth_login_from_setup` used to call
+    `_update_config_for_provider("xai-oauth")` (and token save flipped
+    `active_provider`), so `hermes setup tts` OAuth login hijacked the main
+    chat provider.
+    """
+    hermes_home = tmp_path / "hermes"
+    hermes_home.mkdir(parents=True, exist_ok=True)
+    monkeypatch.setenv("HERMES_HOME", str(hermes_home))
+
+    auth_path = hermes_home / "auth.json"
+    auth_path.write_text(
+        json.dumps(
+            {
+                "version": 1,
+                "active_provider": "openrouter",
+                "providers": {},
+            }
+        ),
+        encoding="utf-8",
+    )
+    config_path = hermes_home / "config.yaml"
+    config_path.write_text(
+        yaml.safe_dump(
+            {
+                "model": {
+                    "provider": "openrouter",
+                    "default": "anthropic/claude-sonnet-4",
+                    "base_url": "https://openrouter.ai/api/v1",
+                },
+                "tts": {"provider": "edge"},
+            }
+        ),
+        encoding="utf-8",
+    )
+
+    monkeypatch.setattr(
+        "hermes_cli.auth._xai_oauth_device_code_login",
+        lambda **kwargs: {
+            "tokens": {
+                "access_token": "tts-xai-access",
+                "refresh_token": "tts-xai-refresh",
+                "id_token": "",
+                "token_type": "Bearer",
+            },
+            "discovery": {"token_endpoint": "https://auth.x.ai/oauth2/token"},
+            "redirect_uri": "",
+            "base_url": "https://api.x.ai/v1",
+            "last_refresh": "2026-07-25T12:00:00Z",
+        },
+    )
+    monkeypatch.setattr("hermes_cli.auth._is_remote_session", lambda: True)
+
+    from hermes_cli.setup import _run_xai_oauth_login_from_setup
+
+    assert _run_xai_oauth_login_from_setup() is True
+
+    auth = json.loads(auth_path.read_text(encoding="utf-8"))
+    assert auth["active_provider"] == "openrouter"
+    xai_state = auth["providers"]["xai-oauth"]
+    assert xai_state["tokens"]["access_token"] == "tts-xai-access"
+    assert xai_state["tokens"]["refresh_token"] == "tts-xai-refresh"
+
+    config = yaml.safe_load(config_path.read_text(encoding="utf-8"))
+    assert config["model"]["provider"] == "openrouter"
+    assert config["model"]["base_url"] == "https://openrouter.ai/api/v1"
+    assert config["model"]["default"] == "anthropic/claude-sonnet-4"