Add CustomProvider for custom OpenAI compatible LLM providers

backend/src/dna/llm_providers/custom_provider.py

@@ -0,0 +1,27 @@
+"""Custom OpenAI Compatible LLM Provider.
+
+Custom OpenAI Compatible implementation of the LLM provider interface.
+"""
+
+import os
+
+from openai import AsyncOpenAI
+
+from dna.llm_providers.llm_provider_base import LLMProviderBase
+
+
+class CustomProvider(LLMProviderBase):
+    """Custom OpenAI Compatible implementation of the LLM provider."""
+
+    LLM_PROVIDER_NAME = "CUSTOM_LLM"
+
+    DEFAULT_MODEL = "gpt-oss-20b"
+    DEFAULT_URL = "http://localhost:11434/v1"
+
+    def _get_provider_client(self):
+        """Construct an instance of the LLM provider's client."""
+        return AsyncOpenAI(
+            api_key=self.api_key,
+            base_url=os.getenv(f"{self.LLM_PROVIDER_NAME}_URL", self.DEFAULT_URL),
+            timeout=self.timeout,
+        )

backend/src/dna/llm_providers/llm_provider_base.py

@@ -346,4 +346,9 @@ def get_llm_provider() -> LLMProviderBase:
 
         return OpenAIProvider()
 
+    if provider_type == "custom":
+        from dna.llm_providers.custom_provider import CustomProvider
+
+        return CustomProvider()
+
     raise ValueError(f"Unknown LLM provider: {provider_type}")