fix(github_copilot): preserve system prompts and auto-add headers

docs/my-website/docs/providers/github_copilot.md

@@ -35,11 +35,10 @@ from litellm import completion
 
 response = completion(
     model="github_copilot/gpt-4",
-    messages=[{"role": "user", "content": "Write a Python function to calculate fibonacci numbers"}],
-    extra_headers={
-        "editor-version": "vscode/1.85.1",
-        "Copilot-Integration-Id": "vscode-chat"
-    }
+    messages=[
+        {"role": "system", "content": "You are a helpful coding assistant"},
+        {"role": "user", "content": "Write a Python function to calculate fibonacci numbers"}
+    ]
 )
 print(response)
 ```
@@ -50,11 +49,7 @@ from litellm import completion
 stream = completion(
     model="github_copilot/gpt-4",
     messages=[{"role": "user", "content": "Explain async/await in Python"}],
-    stream=True,
-    extra_headers={
-        "editor-version": "vscode/1.85.1",
-        "Copilot-Integration-Id": "vscode-chat"
-    }
+    stream=True
 )
 
 for chunk in stream:
@@ -134,11 +129,7 @@ client = OpenAI(
 # Non-streaming response
 response = client.chat.completions.create(
     model="github_copilot/gpt-4",
-    messages=[{"role": "user", "content": "How do I optimize this SQL query?"}],
-    extra_headers={
-        "editor-version": "vscode/1.85.1",
-        "Copilot-Integration-Id": "vscode-chat"
-    }
+    messages=[{"role": "user", "content": "How do I optimize this SQL query?"}]
 )
 
 print(response.choices[0].message.content)
@@ -156,11 +147,7 @@ response = litellm.completion(
     model="litellm_proxy/github_copilot/gpt-4",
     messages=[{"role": "user", "content": "Review this code for bugs"}],
     api_base="http://localhost:4000",
-    api_key="your-proxy-api-key",
-    extra_headers={
-        "editor-version": "vscode/1.85.1",
-        "Copilot-Integration-Id": "vscode-chat"
-    }
+    api_key="your-proxy-api-key"
 )
 
 print(response.choices[0].message.content)
@@ -174,8 +161,6 @@ print(response.choices[0].message.content)
 curl http://localhost:4000/v1/chat/completions \
   -H "Content-Type: application/json" \
   -H "Authorization: Bearer your-proxy-api-key" \
-  -H "editor-version: vscode/1.85.1" \
-  -H "Copilot-Integration-Id: vscode-chat" \
   -d '{
     "model": "github_copilot/gpt-4",
     "messages": [{"role": "user", "content": "Explain this error message"}]
@@ -211,9 +196,11 @@ export GITHUB_COPILOT_API_KEY_FILE="api-key.json"
 
 ### Headers
 
-GitHub Copilot supports various editor-specific headers:
+LiteLLM automatically injects the required GitHub Copilot headers (simulating VSCode). You don't need to specify them manually.
 
-```python showLineNumbers title="Common Headers"
+If you want to override the defaults (e.g., to simulate a different editor), you can use `extra_headers`:
+
+```python showLineNumbers title="Custom Headers (Optional)"
 extra_headers = {
     "editor-version": "vscode/1.85.1",           # Editor version
     "editor-plugin-version": "copilot/1.155.0",  # Plugin version

docs/my-website/docs/proxy/config_settings.md

@@ -94,7 +94,7 @@ litellm_settings:
       # /chat/completions, /completions, /embeddings, /audio/transcriptions
     mode: default_off # if default_off, you need to opt in to caching on a per call basis
     ttl: 600 # ttl for caching
-    disable_copilot_system_to_assistant: False # If false (default), converts all 'system' role messages to 'assistant' for GitHub Copilot compatibility. Set to true to disable this behavior.
+    disable_copilot_system_to_assistant: False # DEPRECATED - GitHub Copilot API supports system prompts.
 
 callback_settings:
   otel:
@@ -197,7 +197,7 @@ router_settings:
 | disable_add_transform_inline_image_block | boolean | For Fireworks AI models - if true, turns off the auto-add of `#transform=inline` to the url of the image_url, if the model is not a vision model. |
 | disable_hf_tokenizer_download | boolean | If true, it defaults to using the openai tokenizer for all models (including huggingface models). |
 | enable_json_schema_validation | boolean | If true, enables json schema validation for all requests. |
-| disable_copilot_system_to_assistant | boolean | If false (default), converts all 'system' role messages to 'assistant' for GitHub Copilot compatibility. Set to true to disable this behavior. Useful for tools (like Claude Code) that send system messages, which Copilot does not support. |
+| disable_copilot_system_to_assistant | boolean | **DEPRECATED** - GitHub Copilot API supports system prompts. |
 
 ### general_settings - Reference
 

litellm/llms/github_copilot/chat/transformation.py

@@ -5,7 +5,7 @@
 from litellm.types.llms.openai import AllMessageValues
 
 from ..authenticator import Authenticator
-from ..common_utils import GetAPIKeyError, GITHUB_COPILOT_API_BASE
+from ..common_utils import GetAPIKeyError, GITHUB_COPILOT_API_BASE, get_copilot_default_headers
 
 
 class GithubCopilotConfig(OpenAIConfig):
@@ -43,15 +43,8 @@ def _transform_messages(
         messages,
         model: str,
     ):
-        import litellm
-
-        disable_copilot_system_to_assistant = (
-            litellm.disable_copilot_system_to_assistant
-        )
-        if not disable_copilot_system_to_assistant:
-            for message in messages:
-                if "role" in message and message["role"] == "system":
-                    cast(Any, message)["role"] = "assistant"
+        # GitHub Copilot API now supports system prompts for all models (Claude, GPT, etc.)
+        # No conversion needed - just return messages as-is
         return messages
 
     def validate_environment(
@@ -69,6 +62,14 @@ def validate_environment(
             headers, model, messages, optional_params, litellm_params, api_key, api_base
         )
 
+        # Add Copilot-specific headers (editor-version, user-agent, etc.)
+        try:
+            copilot_api_key = self.authenticator.get_api_key()
+            copilot_headers = get_copilot_default_headers(copilot_api_key)
+            validated_headers = {**copilot_headers, **validated_headers}
+        except GetAPIKeyError:
+            pass  # Will be handled later in the request flow
+
         # Add X-Initiator header based on message roles
         initiator = self._determine_initiator(messages)
         validated_headers["X-Initiator"] = initiator

litellm/main.py

@@ -2442,6 +2442,20 @@ def completion(  # type: ignore # noqa: PLR0915
 
             headers = headers or litellm.headers
 
+            # Add GitHub Copilot headers (same as /responses endpoint does)
+            if custom_llm_provider == "github_copilot":
+                from litellm.llms.github_copilot.common_utils import (
+                    get_copilot_default_headers,
+                )
+                from litellm.llms.github_copilot.authenticator import Authenticator
+
+                copilot_auth = Authenticator()
+                copilot_api_key = copilot_auth.get_api_key()
+                copilot_headers = get_copilot_default_headers(copilot_api_key)
+                if extra_headers:
+                    copilot_headers.update(extra_headers)
+                extra_headers = copilot_headers
+
             if extra_headers is not None:
                 optional_params["extra_headers"] = extra_headers