diff --git a/tests/test_litigation_providers.py b/tests/test_litigation_providers.py
new file mode 100644
index 0000000..251e1ad
--- /dev/null
+++ b/tests/test_litigation_providers.py
@@ -0,0 +1,64 @@
+"""Regression tests for litigation LLM provider factory."""
+
+from __future__ import annotations
+
+import pytest
+
+from litigation.providers.factory import (
+    _openrouter_extra_body,
+    _openrouter_headers,
+    get_provider,
+)
+from litigation.providers.ollama_provider import OllamaProvider
+from litigation.providers.openai_compat_provider import OpenAICompatProvider
+
+
+def test_get_provider_ollama() -> None:
+    provider = get_provider("ollama", "llama3", ollama_base_url="http://localhost:11434")
+    assert isinstance(provider, OllamaProvider)
+    assert provider.model == "llama3"
+    assert provider.base_url == "http://localhost:11434"
+
+
+def test_get_provider_lm_studio() -> None:
+    provider = get_provider("lm_studio", "local-model")
+    assert isinstance(provider, OpenAICompatProvider)
+    assert provider.model == "local-model"
+    assert provider.api_key == "lm-studio"
+    assert provider.base_url == "http://localhost:1234/v1"
+
+
+def test_get_provider_openrouter_with_config(monkeypatch: pytest.MonkeyPatch) -> None:
+    monkeypatch.setenv("OPENROUTER_API_KEY", "test-key")
+    cfg = {
+        "app_attribution": {"http_referer": "https://example.com", "x_title": "Court App"},
+        "provider": {"sort": "price"},
+        "user": "uid-42",
+    }
+    provider = get_provider("openrouter", "anthropic/claude", openrouter_config=cfg)
+    assert isinstance(provider, OpenAICompatProvider)
+    assert provider.api_key == "test-key"
+    assert provider.default_headers["HTTP-Referer"] == "https://example.com"
+    assert provider.default_headers["X-Title"] == "Court App"
+    assert provider.extra_body["provider"] == {"sort": "price"}
+    assert provider.extra_body["user"] == "uid-42"
+
+
+def test_get_provider_openrouter_missing_api_key(monkeypatch: pytest.MonkeyPatch) -> None:
+    monkeypatch.delenv("OPENROUTER_API_KEY", raising=False)
+    with pytest.raises(ValueError, match="OPENROUTER_API_KEY"):
+        get_provider("openrouter", "model")
+
+
+def test_get_provider_unknown_raises() -> None:
+    with pytest.raises(ValueError, match="Unknown provider"):
+        get_provider("azure", "model")
+
+
+def test_openrouter_headers_skips_invalid_attribution() -> None:
+    assert _openrouter_headers({"app_attribution": "not-a-dict"}) == {}
+
+
+def test_openrouter_extra_body_skips_empty_provider_prefs() -> None:
+    assert _openrouter_extra_body({"provider": {}}) == {}
+    assert _openrouter_extra_body({"user": ""}) == {}