fix(agent): honor model.default_headers for custom OpenAI-compatible providers (#40033)

Custom OpenAI-compatible endpoints sitting behind a gateway/WAF can reject the OpenAI Python SDK's default identifying headers (User-Agent: OpenAI/Python, X-Stainless-*) and return an opaque 502/4xx even though the same request body succeeds under curl. There was no supported way to override those headers. Add a model.default_headers config key whose values are merged onto the OpenAI client's default_headers, taking precedence over provider- and SDK-supplied defaults. Applied at client construction and on every credential swap / client rebuild so the override survives reconnects. No-op for native Anthropic / Bedrock modes and when unconfigured.
2026-06-07 02:02:40 -07:00
parent f5c3fc319c
commit a216ff839b
4 changed files with 158 additions and 0 deletions
@@ -176,6 +176,103 @@ def test_openrouter_headers_include_response_cache_when_enabled(mock_openai):
    assert headers["X-OpenRouter-Cache-TTL"] == "600"


+# ---------------------------------------------------------------------------
+# model.default_headers — user-configured overrides (#40033)
+# ---------------------------------------------------------------------------
+
+
+@patch("run_agent.OpenAI")
+def test_user_default_headers_override_sdk_user_agent(mock_openai):
+    """``model.default_headers`` lets a custom endpoint swap the OpenAI SDK
+    User-Agent that some gateways/WAFs reject (the #40033 reproduction)."""
+    mock_openai.return_value = MagicMock()
+    agent = AIAgent(
+        api_key="test-key",
+        base_url="http://localhost:8080/v1",
+        model="my-custom-model",
+        provider="custom",
+        quiet_mode=True,
+        skip_context_files=True,
+        skip_memory=True,
+    )
+
+    with patch("hermes_cli.config.load_config", return_value={
+        "model": {"default_headers": {"User-Agent": "curl/8.7.1", "X-Extra": "1"}},
+    }):
+        agent._apply_client_headers_for_base_url("http://localhost:8080/v1")
+
+    headers = agent._client_kwargs["default_headers"]
+    assert headers["User-Agent"] == "curl/8.7.1"
+    assert headers["X-Extra"] == "1"
+
+
+@patch("run_agent.OpenAI")
+def test_user_default_headers_win_over_provider_defaults(mock_openai):
+    """User headers take precedence but leave untouched provider defaults intact."""
+    mock_openai.return_value = MagicMock()
+    agent = AIAgent(
+        api_key="test-key",
+        base_url="https://openrouter.ai/api/v1",
+        model="test/model",
+        quiet_mode=True,
+        skip_context_files=True,
+        skip_memory=True,
+    )
+
+    with patch("hermes_cli.config.load_config", return_value={
+        "model": {"default_headers": {"X-Title": "MyApp"}},
+    }):
+        agent._apply_client_headers_for_base_url("https://openrouter.ai/api/v1")
+
+    headers = agent._client_kwargs["default_headers"]
+    assert headers["X-Title"] == "MyApp"  # user override wins
+    assert headers["HTTP-Referer"] == "https://hermes-agent.nousresearch.com"  # default preserved
+
+
+@patch("run_agent.OpenAI")
+def test_no_user_default_headers_leaves_provider_defaults_untouched(mock_openai):
+    mock_openai.return_value = MagicMock()
+    agent = AIAgent(
+        api_key="test-key",
+        base_url="https://openrouter.ai/api/v1",
+        model="test/model",
+        quiet_mode=True,
+        skip_context_files=True,
+        skip_memory=True,
+    )
+
+    with patch("hermes_cli.config.load_config", return_value={"model": {}}):
+        agent._apply_client_headers_for_base_url("https://openrouter.ai/api/v1")
+
+    headers = agent._client_kwargs["default_headers"]
+    assert headers["HTTP-Referer"] == "https://hermes-agent.nousresearch.com"
+    assert "User-Agent" not in headers  # nothing injected when unconfigured
+
+
+@patch("run_agent.OpenAI")
+def test_user_default_headers_skipped_for_anthropic_mode(mock_openai):
+    """Anthropic/Bedrock modes don't use the OpenAI client — never touched."""
+    mock_openai.return_value = MagicMock()
+    agent = AIAgent(
+        api_key="test-key",
+        base_url="http://localhost:8080/v1",
+        model="my-custom-model",
+        provider="custom",
+        quiet_mode=True,
+        skip_context_files=True,
+        skip_memory=True,
+    )
+    agent.api_mode = "anthropic_messages"
+    agent._client_kwargs = {}
+
+    with patch("hermes_cli.config.load_config", return_value={
+        "model": {"default_headers": {"User-Agent": "curl/8.7.1"}},
+    }):
+        agent._apply_user_default_headers()
+
+    assert "default_headers" not in agent._client_kwargs
+
+
@patch("run_agent.OpenAI")
 def test_openrouter_headers_no_cache_when_disabled(mock_openai):
    """When openrouter.response_cache is False, no cache headers are sent."""