Storage

Extensions that persist data (cache, rate limits, usage, budget) use a shared storage backend. Three backends are available.

Memory (default)

In-memory storage using concurrent hash maps. Fast, but data is lost on restart.

[storage]
kind = "memory"

This is the default when no [storage] section is present. No feature flag required.

SQLite

Persistent storage using SQLite via async pooled connections.

[storage]
kind = "sqlite"
path = "crabllm.db"

Requires the storage-sqlite feature:

cargo install crabllm --features storage-sqlite

The database file is created automatically if it doesn’t exist. Uses two tables (kv and counters) with atomic increment via INSERT ... ON CONFLICT ... RETURNING.

Redis

Remote persistent storage using Redis async multiplexed connections.

[storage]
kind = "redis"
path = "redis://127.0.0.1:6379"

Requires the storage-redis feature:

cargo install crabllm --features storage-redis

Supports standard Redis URLs. Increment maps to INCRBY, key listing uses SCAN with prefix glob patterns.

How Extensions Use Storage

Each extension namespaces its keys with a 4-byte prefix to avoid collisions: