Initial commit: FastGPT Python SDK Phase 1

Implement core infrastructure:

- BaseClientMixin with retry logic and validation
- FastGPTClient base class with httpx
- ChatClient with 11 chat operation methods
- AppClient for analytics and logs
- Custom exceptions (APIError, AuthenticationError, etc.)
- Package configuration (pyproject.toml, setup.py)
- Documentation (README.md, CLAUDE.md)
- Basic usage examples

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

examples/basic_usage.py

@@ -0,0 +1,125 @@
+"""Basic usage example for FastGPT Python SDK."""
+
+from fastgpt_client import ChatClient
+from dotenv import load_dotenv
+import os
+
+load_dotenv()
+
+# Configure your API key and base URL
+API_KEY = os.getenv("API_KEY")
+BASE_URL = os.getenv("BASE_URL")
+
+
+def simple_chat():
+    """Simple chat completion example."""
+    with ChatClient(api_key=API_KEY, base_url=BASE_URL) as client:
+        response = client.create_chat_completion(
+            messages=[{"role": "user", "content": "Hello! What's AI?"}],
+            stream=False
+        )
+        response.raise_for_status()
+        result = response.json()
+
+        print("Response:", result['choices'][0]['message']['content'])
+
+
+def streaming_chat():
+    """Streaming chat completion example."""
+    import json
+
+    with ChatClient(api_key=API_KEY, base_url=BASE_URL) as client:
+        response = client.create_chat_completion(
+            messages=[{"role": "user", "content": "Tell me a short story"}],
+            stream=True
+        )
+
+        print("Streaming response: ", end="")
+        for line in response.iter_lines():
+            if line.startswith("data:"):
+                data = line[5:].strip()
+                if data and data != "[DONE]":
+                    chunk = json.loads(data)
+                    if "choices" in chunk and chunk["choices"]:
+                        delta = chunk["choices"][0].get("delta", {})
+                        content = delta.get("content", "")
+                        if content:
+                            print(content, end="", flush=True)
+        print()
+
+
+def chat_with_context():
+    """Chat with context using chatId example."""
+    with ChatClient(api_key=API_KEY, base_url=BASE_URL) as client:
+        chat_id = os.getenv("CHAT_ID")
+
+        # First message
+        print("User: What's AI?")
+        response = client.create_chat_completion(
+            messages=[{"role": "user", "content": "What's AI?"}],
+            chatId=chat_id,
+            stream=False
+        )
+        response.raise_for_status()
+        result = response.json()
+        print(f"AI: {result['choices'][0]['message']['content']}\n")
+
+        # Second message (continues the conversation)
+        print("User: Tell me more about it")
+        response = client.create_chat_completion(
+            messages=[{"role": "user", "content": "Tell me more about it"}],
+            chatId=chat_id,  # Same chatId maintains context
+            stream=False
+        )
+        response.raise_for_status()
+        result = response.json()
+        print(f"AI: {result['choices'][0]['message']['content']}")
+
+
+def get_histories():
+    """Get chat histories example."""
+    with ChatClient(api_key=API_KEY, base_url=BASE_URL) as client:
+        # You need to replace this with your actual app ID
+        app_id = os.getenv("APP_ID")
+
+        try:
+            histories = client.get_chat_histories(
+                appId=app_id,
+                offset=0,
+                pageSize=20,
+                source="api"
+            )
+            histories.raise_for_status()
+            data = histories.json()
+
+            print(f"Total chats: {data['data']['total']}")
+            for chat in data['data']['list']:
+                print(f"  - {chat['title']}: {chat['chatId']}")
+        except Exception as e:
+            print(f"Error: {e}")
+
+
+if __name__ == "__main__":
+    print("=== Simple Chat ===")
+    try:
+        simple_chat()
+    except Exception as e:
+        print(f"Error: {e}")
+
+    print("\n=== Streaming Chat ===")
+    try:
+        streaming_chat()
+    except Exception as e:
+        print(f"Error: {e}")
+
+    print("\n=== Chat with Context ===")
+    try:
+        chat_with_context()
+    except Exception as e:
+        print(f"Error: {e}")
+
+    print("\n=== Get Histories ===")
+    try:
+        get_histories()
+    except Exception as e:
+        print(f"Error: {e}")