omnigraph/docs/architecture.md
Ragnor Comerford a335d98854
Refactor AGENTS.md from encyclopedia to map; move spec into docs/
Splits the 990-line AGENTS.md into a 184-line map (architecture,
where-to-find index, always-on invariants, capability matrix,
maintenance contract) plus 18 new docs/*.md files holding the deep
content per topic (storage, schema and query languages, indexes,
embeddings, branches/commits, runs, merge, changes, execution, policy,
server, CLI reference, audit, errors, CI, constants, v0.3.1 notes).

Adds scripts/check-agents-md.sh and a check_agents_md CI job that
verifies every docs/ link in AGENTS.md resolves and every doc in the
canonical set is linked. CLAUDE.md remains a symlink to AGENTS.md.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
2026-04-28 23:31:08 +02:00

69 lines
6 KiB
Markdown

# Architecture
OmniGraph is a typed property-graph engine built as a coordination layer over many Lance datasets, with Git-style branches and commits across the whole graph, multi-modal querying (vector + FTS + BM25 + RRF + graph traversal) in one runtime, an HTTP server with Cedar policy, and a CLI driven by a single `omnigraph.yaml`.
## Stack
```
┌──────────────────────────────────────────────────────────────────┐
│ CLI (omnigraph) HTTP Server (omnigraph-server, Axum) │
│ - 13 cmd families - REST + OpenAPI │
│ - Aliases, configs - Bearer auth + Cedar policy │
└──────────────────────────────┬───────────────────────────────────┘
┌──────────────────────────────▼───────────────────────────────────┐
│ omnigraph-compiler │
│ - Pest grammars: schema.pest, query.pest │
│ - Catalog (Node/Edge/Interface types) │
│ - IR + lowering (NodeScan / Expand / Filter / AntiJoin) │
│ - Schema migration planner │
│ - Embedding client (OpenAI-style for query-time normalization) │
└──────────────────────────────┬───────────────────────────────────┘
┌──────────────────────────────▼───────────────────────────────────┐
│ omnigraph (engine) │
│ - GraphCoordinator + ManifestRepo (__manifest) │
│ - CommitGraph (_graph_commits.lance) │
│ - RunRegistry (_graph_runs.lance, __run__ branches) │
│ - GraphIndex (CSR/CSC) + RuntimeCache (LRU 8) │
│ - exec::query / mutation / merge │
│ - Embedding client (Gemini for runtime ingest) │
└──────────────────────────────┬───────────────────────────────────┘
┌──────────────────────────────▼───────────────────────────────────┐
│ Lance 4.x (per-table dataset) │
│ - Columnar (Arrow) storage, fragments │
│ - Manifest versions per dataset │
│ - Per-dataset branches (copy-on-write) │
│ - Indexes: BTREE, Inverted (FTS/BM25), IVF/HNSW vector │
│ - merge_insert (upsert), append, delete │
│ - compact_files, cleanup_old_versions │
└──────────────────────────────┬───────────────────────────────────┘
┌──────────────────────────────▼───────────────────────────────────┐
│ Object store: local FS, S3, RustFS, MinIO, S3-compatible │
└──────────────────────────────────────────────────────────────────┘
```
## L1 / L2 framing
Throughout the docs, capabilities are split into:
- **L1 — Inherited from Lance**: what OmniGraph gets "for free" by sitting on top of the Lance dataset format (columnar Arrow storage, per-dataset versions and branches, index types, `merge_insert`, `compact_files` / `cleanup_old_versions`).
- **L2 — Added by OmniGraph**: typing (schema language), graph semantics, multi-dataset coordination via `__manifest`, graph-level branches and commits, the `.gq` query language and IR, the topology index, the HTTP server, Cedar policy, the CLI.
## Concurrency model
- **MVCC**: every Lance write bumps a per-dataset version; the OmniGraph manifest version coordinates which sub-table versions are visible together.
- **Snapshot isolation**: a query holds one `Snapshot` for its lifetime; concurrent writes don't leak in.
- **Cross-branch isolation**: copy-on-write means readers and writers on different branches don't block each other.
- **Run isolation**: each transactional run lives on its own `__run__<id>` branch.
- **Schema-apply lock**: `__schema_apply_lock__` system branch serializes schema migrations.
- **Fail-points** (`failpoints` cargo feature): `failpoints::maybe_fail("operation.step")?` in `branch_create`, publish, etc., for deterministic failure injection in tests.
## Workspace crates
- `omnigraph-compiler` — schema and query grammars, catalog, IR, lowering, type checker, lint, migration planner, OpenAI-style embedding client.
- `omnigraph` (engine, published as `omnigraph-engine` on crates.io since v0.2.2) — the Lance-backed runtime: manifest, commit graph, run registry, snapshot, exec, merge, loader, Gemini embedding client.
- `omnigraph-cli` — the `omnigraph` binary.
- `omnigraph-server` — the `omnigraph-server` binary (Axum HTTP server).