Shutter

Web Content Distillation Service

Open. Capture. Close.

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Overview

Shutter is a web content distillation layer that sits between LLM agents and raw web pages. It fetches URLs, uses a cheap/fast LLM to extract only the relevant content based on a query, and returns clean, focused results.

Two key benefits:

1. Token efficiency — Agents get 200 tokens instead of 20,000
2. Prompt injection defense — Raw page content never reaches the driver model; injections never make it past the aperture

Quick Start

Installation

# Install via UV (recommended)
uv add grove-shutter

# Or via pip
pip install grove-shutter

# Or run directly without installing
uvx grove-shutter --help

First Run Setup

# Interactive setup (creates ~/.shutter/config.toml)
shutter setup

# Or set environment variables
export OPENROUTER_API_KEY="sk-or-v1-..."
export TAVILY_API_KEY="tvly-..."  # optional, for enhanced fetching

CLI Usage

# Basic extraction
shutter "https://stripe.com/pricing" -q "What are the transaction fees?"

# Choose model tier
shutter "https://docs.python.org/3/library/asyncio.html" -q "How do I create a task?" --model code

# View offenders list
shutter offenders

# Clear offenders list
shutter clear-offenders

Programmatic Usage

from grove_shutter import shutter

result = await shutter(
    url="https://stripe.com/pricing",
    query="What are the transaction fees?",
    model="fast",
    max_tokens=500
)

print(result.extracted)
# Output: "2.9% + 30¢ per successful card charge. Additional 0.5% for..."

# Check for prompt injection
if result.prompt_injection:
    print(f"Injection detected: {result.prompt_injection.type}")
    print(f"Confidence: {result.prompt_injection.confidence}")

Configuration

Configuration File

Shutter stores configuration at ~/.shutter/config.toml:

[api]
openrouter_key = "sk-or-v1-..."
tavily_key = "tvly-..."  # optional

[defaults]
model = "fast"
max_tokens = 500
timeout = 30000

# Optional: Tune prompt injection detection
[canary]
block_threshold = 0.6  # 0.0-1.0, lower = more sensitive

[canary.weights]
# Override confidence weights for specific patterns
instruction_override = 0.95
role_hijack = 0.40  # Lower if you get false positives on "act as" content

Response Format

Clean Extraction

{
  "url": "https://stripe.com/pricing",
  "extracted": "2.9% + 30¢ per successful card charge. Additional 0.5% for manually entered cards. 1.5% for international cards.",
  "tokens_input": 24500,
  "tokens_output": 42,
  "model_used": "openai/gpt-oss-120b",
  "prompt_injection": null
}

Prompt Injection Detected

{
  "url": "https://malicious.example.com",
  "extracted": null,
  "tokens_input": 8200,
  "tokens_output": 0,
  "model_used": "",
  "prompt_injection": {
    "detected": true,
    "type": "instruction_override",
    "snippet": "...IGNORE ALL PREVIOUS INSTRUCTIONS...",
    "domain_flagged": true,
    "confidence": 0.95,
    "signals": ["instruction_override:0.95"]
  }
}

The prompt_injection object includes:

• confidence: 0.0-1.0 score indicating detection certainty
• signals: List of contributing detection signals for debugging
• domain_flagged: Whether the domain was added to the offenders list

Model Tiers

Tier	Use Case	Model	Speed
fast	Quick extractions, simple queries	openai/gpt-oss-120b (Cerebras)	~2000 tok/s
accurate	Complex extraction, nuanced content	deepseek/deepseek-v3.2	~200 tok/s
research	Web-optimized, longer analysis	alibaba/tongyi-deepresearch-30b-a3b	~150 tok/s
code	Technical docs, code extraction	minimax/minimax-m2.1	~300 tok/s

How It Works

Fetch Chain

Shutter uses a smart fetch chain for JavaScript-rendered content:

1. Jina Reader (primary) — Free JS rendering via r.jina.ai/{url}
2. Tavily (fallback) — SDK-based JS rendering (requires API key)
3. Basic httpx (final) — Direct HTML fetch with trafilatura extraction

Prompt Injection Defense

Shutter uses a 2-phase Canary approach with confidence scoring:

Phase 1: Heuristic Checks (free)

• 17 weighted regex patterns for injection attempts
• Unicode hidden character detection
• Base64 payload detection
• Multi-pattern boost (2+ matches = higher confidence)

Phase 2: LLM Canary (only if heuristics inconclusive)

• Minimal extraction (100 tokens) with output analysis
• Detects instruction-following and topic deviation
• Cost: ~$0.001

If confidence exceeds the threshold (default 0.6), extraction is blocked and the domain is flagged.

Offenders List

Shutter maintains a persistent SQLite database of flagged domains:

• Location: ~/.shutter/offenders.db
• Skip conditions:
  • 3+ detections on the domain
  • Single detection with confidence ≥ 0.90
  • 2+ detections with average confidence ≥ 0.80

This creates trial-and-error defense that improves over time.

Development

Setup

# Clone the repository
git clone https://github.com/AutumnsGrove/Shutter.git
cd Shutter

# Install dependencies with UV
uv sync --dev

# Run tests
uv run pytest

# Format code
uv run black src/ tests/
uv run ruff check src/ tests/

Test Coverage

# Run with coverage
uv run pytest --cov=grove_shutter --cov-report=term-missing

# Current: 120 tests passing

Roadmap

v1.0 — Python Production (Current)

• Core fetch + extraction with OpenRouter
• Jina/Tavily fetch chain for JS rendering
• Canary-based prompt injection detection
• Confidence scoring (0.0-1.0)
• Config-based weight overrides
• SQLite offenders list with smart thresholds
• CLI with setup, offenders commands
• PyPI release (grove-shutter)

v1.5 — Cloudflare Port

• TypeScript Workers implementation
• D1 shared offenders list
• HTTP API with authentication
• NPM package (@groveengine/shutter)

v2.0 — Search

• Multi-URL search queries
• Additional providers (Exa, Brave)
• Result aggregation and deduplication

v3.0 — Caching & Intelligence

• Content caching (R2)
• Injection pattern learning
• Vectorize integration

License

MIT

Links

• Repository: github.com/AutumnsGrove/Shutter
• Documentation: docs/SPEC.md
• Issues: github.com/AutumnsGrove/Shutter/issues

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A shutter controls what reaches the lens. Open it, and light floods in—everything, all at once, overwhelming. But a photographer doesn't want everything. They want the shot. The shutter opens precisely when needed, captures exactly what's in frame, and closes before the noise can follow.