Add Per-Keyspace Typed Keys

CLAUDE.md

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+# CLAUDE.md
+
+This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.
+
+## Project Overview
+
+Datacake is a batteries-included framework for building fault-tolerant distributed data systems in Rust. It implements eventually consistent replication using CRDTs (Conflict-free Replicated Data Types) with hybrid logical clocks, designed as an alternative to Raft consensus for specific use cases.
+
+## Commands
+
+### Building and Testing
+- `cargo build` - Build the entire workspace
+- `cargo test --workspace --exclude simulation-tests --features test-utils` - Run main test suite
+- `cargo test --doc --workspace --exclude simulation-tests --features test-utils` - Run documentation tests
+- `cargo nextest run --workspace --exclude simulation-tests --retries 3 --features test-utils` - Run tests with nextest (preferred)
+- `cargo nextest run -p simulation-tests --retries 3` - Run simulation tests separately
+
+### Code Quality
+- `cargo fmt --all -- --check` - Check code formatting (use nightly toolchain)
+- `cargo clippy --workspace --all-features --tests --examples --bins -- -Dclippy::todo` - Run clippy lints
+- `cargo hack check --all --ignore-private --each-feature --no-dev-deps` - Check feature combinations
+
+### Development Requirements
+- Protobuf compiler (`protoc`) is required for building
+- `cargo-hack` tool needed for feature checking: `cargo install cargo-hack`
+- `cargo-nextest` tool recommended for testing: `cargo install cargo-nextest`
+
+## Architecture
+
+### Workspace Structure
+Datacake is organized as a Cargo workspace with the following key crates:
+
+- **`datacake-crdt`** - Core CRDT implementation with HLCTimestamp (Hybrid Logical Clock)
+- **`datacake-node`** - Cluster membership system built on chitchat (scuttlebutt gossip protocol)
+- **`datacake-rpc`** - Zero-copy RPC framework using HTTP/2 and rkyv serialization
+- **`datacake-eventual-consistency`** - High-level eventually consistent store framework
+- **`datacake-sqlite`** - Pre-built SQLite storage implementation
+- **`datacake-lmdb`** - Pre-built LMDB storage implementation
+
+### Core Concepts
+
+**Node Architecture**: Datacake uses a node-based architecture where each node runs a membership system, RPC server, and can have multiple extensions attached at runtime.
+
+**Extensions System**: The framework follows an extension pattern where storage backends and replication logic are implemented as `ClusterExtension` traits that can be added to nodes dynamically.
+
+**CRDT-Based Replication**: State synchronization uses ORSwot (Observed-Remove Set without Tombstones) CRDTs with hybrid logical clocks for causality tracking.
+
+**Storage Abstraction**: The `Storage` trait defines the interface for persistent backends, with implementations for SQLite and LMDB provided.
+
+### Key Files
+
+- `src/lib.rs` - Main crate re-exports with feature gates
+- `datacake-eventual-consistency/src/storage.rs` - Core storage trait definition
+- `datacake-node/src/lib.rs` - Node membership and extension system
+- `datacake-crdt/src/orswot.rs` - CRDT implementation
+- `datacake-rpc/src/` - RPC framework implementation
+
+## Development Guidelines
+
+### Features and Optional Dependencies
+The project uses extensive feature flags. Default features include `datacake-crdt`, `datacake-rpc`, `datacake-eventual-consistency`, and `datacake-node`. Storage backends (SQLite/LMDB) and rkyv serialization support are optional.
+
+### Testing Strategy
+- Unit tests for individual components
+- Integration tests in `datacake-eventual-consistency/tests/`
+- Simulation tests in `simulation-tests/` crate for distributed scenarios
+- Test utilities provided in `test-helper/` crate
+
+### Code Style
+- Uses rustfmt with custom configuration in `rustfmt.toml`
+- Max width: 89 characters
+- Nightly rustfmt features enabled
+- Clippy with strict linting including `-Dclippy::todo`
+
+## Examples
+
+Check the `examples/` directory for practical implementations:
+- `examples/replicated-kv/` - A distributed key-value store built on SQLite