# Episteme (StemeDB)

A probabilistic knowledge graph database that stores Claims, not Facts. Append-only Merkle DAG with read-time resolution via Lenses.

**Core Concept:** "Git for Truth" - conflicting assertions coexist, resolved at query time through Consensus, Recency, Authority, or custom Lenses.

## Find Your Guide

| If you need to... | Read this |
|-------------------|-----------|
| **Understand the vision** | [vision.md](./vision.md) |
| **Understand architecture** | [architecture.md](./architecture.md) |
| **See the roadmap** | [roadmap.md](./roadmap.md) |
| **Write Rust code** | [.claude/guides/backend/rust-guidelines.md](.claude/guides/backend/rust-guidelines.md) |
| **Set up local dev** | [.claude/guides/local/setup.md](.claude/guides/local/setup.md) |
| **Run tests** | [.claude/guides/local/testing.md](.claude/guides/local/testing.md) |
| **Work on storage/DAG** | Load skill: `stemedb-core` |
| **Implement a Lens** | Load skill: `stemedb-lens` |
| **Plan a milestone** | `/plan-milestone` command |

## Critical Rules

- **Append-Only:** NEVER mutate existing Assertions. Create new ones.
- **Content-Addressed:** Assertion ID = BLAKE3 hash of content.
- **No Unwrap:** NEVER use `unwrap()` or `expect()` in production code.
- **Defensive Writes:** All writes go through WAL with fsync.
- **Zero-Copy:** Use `rkyv` for serialization.

## Quick Reference

```bash
# Build
cargo build --workspace

# Test
cargo test --workspace

# Lint (must pass before commit)
cargo clippy --workspace -- -D warnings
cargo fmt --check
```

## Specialized Agents

| Domain | Agent | When to use |
|--------|-------|-------------|
| General Rust | `primary-developer` | Feature implementation, refactoring |
| Code Quality | `rust-quality-engineer` | Reviews, test coverage, clippy |
| Storage | `storage-engine-architect` | WAL, LSM, crash recovery |
| Graph Engine | `rust-graph-engine-architect` | Lock-free structures, cache optimization |
| Defensive | `defensive-systems-architect` | Rate limiting, circuit breakers, hostile input |
| Lenses | `stemedb-lens-architect` | Query resolution, ranking algorithms |
| Planning | `stemedb-planner` | Milestone planning, roadmap |

## Architecture Overview

```
Write Path (Spine):           Read Path (Cortex):
[Agent] -> [Ingestion]        [Agent] <- [Lens Engine]
              |                              |
              v                              |
         [WAL/Fsync]                  [Index Lookup]
              |                              |
              v                              |
         [KV Store] <--------------------+
```

## Crates

| Crate | Purpose |
|-------|---------|
| `stemedb-core` | Assertion struct, types, storage traits |
| `stemedb-wal` | Write-ahead log (planned) |
| `stemedb-index` | Subject/Predicate indexing (planned) |
| `stemedb-lens` | Lens trait and implementations (planned) |