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Systems & Architecture8 min read•Yashvardhan Thanvi (LLMSlim Author & Core Maintainer)•Published: July 15, 2026 (Updated: July 15, 2026)

Reverse Proxy Gateway Integration: Context Compression in Production Python Gateways

Deploying Transparent Pre-Dispatch Context Optimization in Enterprise Services

Mathematical Intuition & Formal Derivation

Intercepts POST payloads, measures prompt token length, applies compression if length exceeds threshold N_min, and forwards payload to provider.

Key Takeaways

  • 01.Gateway proxy patterns decouple prompt optimization logic from downstream application code.
  • 02.Threshold-based routing compresses long RAG contexts while bypassing short query requests.
  • 03.Preserves original system messages and API request/response contracts.

1. Production FastAPI Interceptor Implementation

Implementing a transparent reverse proxy route:
gateway_proxy.py
from fastapi import FastAPI, Request, Response
import httpx
from llmslim import compress

app = FastAPI()
http_client = httpx.AsyncClient()

MIN_COMPRESSION_THRESHOLD = 500  # Only compress prompts over 500 tokens

@app.post("/v1/chat/completions")
async def proxy_chat_completions(request: Request):
    payload = await request.json()
    messages = payload.get("messages", [])
    
    # Process system and context messages
    for msg in messages:
        content = msg.get("content", "")
        if len(content) > MIN_COMPRESSION_THRESHOLD:
            compressed = compress(content, target_ratio=0.5).compressed_text
            msg["content"] = compressed

    # Forward to target LLM provider (e.g. OpenAI)
    headers = {k: v for k, v in request.headers.items() if k.lower() != "host"}
    provider_res = await http_client.post(
        "https://api.openai.com/v1/chat/completions",
        json=payload,
        headers=headers
    )
    
    return Response(
        content=provider_res.content,
        status_code=provider_res.status_code,
        headers=dict(provider_res.headers)
    )

Academic Literature & Peer-Reviewed References