Merge pull request fuergaosi233#31 from teremterem/transparent-anthropic-proxy

Add "transparent Anthropic proxy" mode with PREFERRED_PROVIDER=anthropic

Author: winstondu

.env.example

@@ -4,19 +4,25 @@ OPENAI_API_KEY="sk-..."
 GEMINI_API_KEY="your-google-ai-studio-key"
 
 # Optional: Provider Preference and Model Mapping
-# Controls which provider (google or openai) is preferred for mapping haiku/sonnet.
+# Controls which provider (google, openai, or anthropic) is preferred for mapping haiku/sonnet.
 # Defaults to openai if not set.
+# Set to "anthropic" for "just an Anthropic proxy" mode (no remapping)
 PREFERRED_PROVIDER="openai"
 OPENAI_BASE_URL="https://api.openai.com/v1"
 
 # Optional: Specify the exact models to map haiku/sonnet to.
 # If PREFERRED_PROVIDER=google, these MUST be valid Gemini model names known to the server.
 # Defaults to gemini-2.5-pro-preview-03-25 and gemini-2.0-flash if PREFERRED_PROVIDER=google.
 # Defaults to gpt-4.1 and gpt-4.1-mini if PREFERRED_PROVIDER=openai.
+# These are IGNORED when PREFERRED_PROVIDER=anthropic (models are not remapped).
 # BIG_MODEL="gpt-4.1"
 # SMALL_MODEL="gpt-4.1-mini"
 
 # Example Google mapping:
 # PREFERRED_PROVIDER="google"
 # BIG_MODEL="gemini-2.5-pro-preview-03-25"
 # SMALL_MODEL="gemini-2.0-flash"
+
+# Example "just an Anthropic proxy" mode:
+# PREFERRED_PROVIDER="anthropic"
+# (BIG_MODEL and SMALL_MODEL are ignored in this mode)

README.md

@@ -1,8 +1,8 @@
 # Anthropic API Proxy for Gemini & OpenAI Models 🔄
 
-**Use Anthropic clients (like Claude Code) with Gemini or OpenAI backends.** 🤝
+**Use Anthropic clients (like Claude Code) with Gemini, OpenAI, or direct Anthropic backends.** 🤝
 
-A proxy server that lets you use Anthropic clients with Gemini or OpenAI models via LiteLLM. 🌉
+A proxy server that lets you use Anthropic clients with Gemini, OpenAI, or Anthropic models themselves (a transparent proxy of sorts), all via LiteLLM. 🌉
 
 
 ![Anthropic API Proxy](pic.png)
@@ -39,13 +39,14 @@ A proxy server that lets you use Anthropic clients with Gemini or OpenAI models
    *   `ANTHROPIC_API_KEY`: (Optional) Needed only if proxying *to* Anthropic models.
    *   `OPENAI_API_KEY`: Your OpenAI API key (Required if using the default OpenAI preference or as fallback).
    *   `GEMINI_API_KEY`: Your Google AI Studio (Gemini) API key (Required if PREFERRED_PROVIDER=google).
-   *   `PREFERRED_PROVIDER` (Optional): Set to `openai` (default) or `google`. This determines the primary backend for mapping `haiku`/`sonnet`.
-   *   `BIG_MODEL` (Optional): The model to map `sonnet` requests to. Defaults to `gpt-4.1` (if `PREFERRED_PROVIDER=openai`) or `gemini-2.5-pro-preview-03-25`.
-   *   `SMALL_MODEL` (Optional): The model to map `haiku` requests to. Defaults to `gpt-4.1-mini` (if `PREFERRED_PROVIDER=openai`) or `gemini-2.0-flash`.
+   *   `PREFERRED_PROVIDER` (Optional): Set to `openai` (default), `google`, or `anthropic`. This determines the primary backend for mapping `haiku`/`sonnet`.
+   *   `BIG_MODEL` (Optional): The model to map `sonnet` requests to. Defaults to `gpt-4.1` (if `PREFERRED_PROVIDER=openai`) or `gemini-2.5-pro-preview-03-25`. Ignored when `PREFERRED_PROVIDER=anthropic`.
+   *   `SMALL_MODEL` (Optional): The model to map `haiku` requests to. Defaults to `gpt-4.1-mini` (if `PREFERRED_PROVIDER=openai`) or `gemini-2.0-flash`. Ignored when `PREFERRED_PROVIDER=anthropic`.
 
    **Mapping Logic:**
    - If `PREFERRED_PROVIDER=openai` (default), `haiku`/`sonnet` map to `SMALL_MODEL`/`BIG_MODEL` prefixed with `openai/`.
    - If `PREFERRED_PROVIDER=google`, `haiku`/`sonnet` map to `SMALL_MODEL`/`BIG_MODEL` prefixed with `gemini/` *if* those models are in the server's known `GEMINI_MODELS` list (otherwise falls back to OpenAI mapping).
+   - If `PREFERRED_PROVIDER=anthropic`, `haiku`/`sonnet` requests are passed directly to Anthropic with the `anthropic/` prefix without remapping to different models.
 
 4. **Run the server**:
    ```bash
@@ -132,7 +133,17 @@ PREFERRED_PROVIDER="google"
 # SMALL_MODEL="gemini-2.0-flash" # Optional, it's the default for Google pref
 ```
 
-**Example 3: Use Specific OpenAI Models**
+**Example 3: Use Direct Anthropic ("Just an Anthropic Proxy" Mode)**
+```dotenv
+ANTHROPIC_API_KEY="sk-ant-..."
+PREFERRED_PROVIDER="anthropic"
+# BIG_MODEL and SMALL_MODEL are ignored in this mode
+# haiku/sonnet requests are passed directly to Anthropic models
+```
+
+*Use case: This mode enables you to use the proxy infrastructure (for logging, middleware, request/response processing, etc.) while still using actual Anthropic models rather than being forced to remap to OpenAI or Gemini.*
+
+**Example 4: Use Specific OpenAI Models**
 ```dotenv
 OPENAI_API_KEY="your-openai-key"
 GEMINI_API_KEY="your-google-key"

server.py

@@ -208,8 +208,13 @@ def validate_model_field(cls, v, info): # Renamed to avoid conflict
 
         # --- Mapping Logic --- START ---
         mapped = False
+        if PREFERRED_PROVIDER == "anthropic":
+            # Don't remap to big/small models, just add the prefix
+            new_model = f"anthropic/{clean_v}"
+            mapped = True
+
         # Map Haiku to SMALL_MODEL based on provider preference
-        if 'haiku' in clean_v.lower():
+        elif 'haiku' in clean_v.lower():
             if PREFERRED_PROVIDER == "google" and SMALL_MODEL in GEMINI_MODELS:
                 new_model = f"gemini/{SMALL_MODEL}"
                 mapped = True