> ## Documentation Index
> Fetch the complete documentation index at: https://docs.visualvortexcreatives.dev/llms.txt
> Use this file to discover all available pages before exploring further.

# Semantic Caching

> Stop paying for identical prompts using local vector caching

### Local Semantic Caching

TokenSense includes a local semantic cache powered by `sqlite-vec`. This cache intercepts requests before they hit the LLM provider, saving both cost and latency.

By storing prompt embeddings locally, TokenSense can instantly return identical past responses. This drops your latency to \~1ms and brings your API cost for duplicate questions to \$0.00.

### Usage

```python theme={null}
from tokensense import observe
from tokensense.cache import SQLiteVectorCache
import openai

# Initialize the cache database
cache = SQLiteVectorCache("./tokensense.db")

# Pass the cache to the observe wrapper
client = observe(openai.OpenAI(), cache=cache)

# First call: hits OpenAI API and incurs cost & latency
response1 = client.chat.completions.create(
    model="gpt-4o", 
    messages=[{"role": "user", "content": "Explain async/await"}]
)

# Second call: intercepted instantly, latency ~1ms, cost $0.00
response2 = client.chat.completions.create(
    model="gpt-4o", 
    messages=[{"role": "user", "content": "Explain async/await"}]
)
```

### How it works

1. TokenSense intercepts your prompt.
2. It generates an embedding for the prompt and performs a semantic search in your local SQLite vector database.
3. If an exact match is found within your defined similarity threshold, the cached response is immediately returned.
4. If no match is found, the request proceeds to the provider, and the new response is logged in the cache for future use.