World Graph

The second of ArcFlow's seven layers. Owns everything a graph engine is uniquely good at — identity, topology, mutable state, and the catalog that binds graph queries to whichever storage holds the underlying rows.

The World Graph is what makes ArcFlow a graph database rather than a column store with extra steps. It holds the adjacency lists, the label indexes, the vector indexes, the entity-resolution merges, the charting overlays, the live signals — every fact that can change after it was first written.

What lives here#

If a class is mutable — a charter correcting a play call, a telemetry correction, a derived embedding, an entity-resolution merge, a live signal — it lives in the Graph. If it is an immutable observation, it lives in the Perception Lake.

Why topology stays in the Graph#

Even when both endpoints of an edge are observation rows in the Lake, the edge itself is owned by the Graph. A (:Frame)-[:TRACKED]->(:Frame) relationship is two Lake-resident endpoints plus one Graph-resident edge. The graph engine holds the adjacency in a compressed CSR (compressed-sparse-row) layout; the Lake holds the row payloads.

This decoupling means new observations arriving in the Lake do not require Graph mutation. New edges discovered in post-processing require Graph mutation but no Lake change. Each side evolves at its own pace.

Identity is graph-resident#

Every node — Lake-resident or Graph-resident — has a stable identity owned by the Graph. The catalog resolves an identity to one of two shapes:

• Direct — (partition, row_offset) for exact-row lookup.
• Predicate — (partition, row_predicate) for property-scoped lookup such as entity_id = 'Unit-01'.

A Cypher pattern that touches a Lake-resident label compiles down to a Lake scan; one that touches a Graph-resident label runs against the in-memory tables. The agent writes the same query either way.

Why this matters for agents#

The World Graph is the durable, queryable shape an agent reasons against. It owns:

• Identity — a stable ID an agent can carry across sessions, conversations, and replay windows.
• Connectivity — the edges that turn "rows" into "a world."
• Mutable state — the only place an agent can record a correction, a merge, a derived fact.
• Indexes — the structures that make "find entities like this one" a sub-second operation.

Combined with the Perception Lake, this gives agents two surfaces with one schema: heavy columnar scans go to the Lake, low-latency graph traversal stays in the Graph, and the catalog hides the boundary at query time.

The three boundary rules#

The Lake ↔ Graph boundary is governed by three mechanical rules — see Perception Lake for the full statement. Summary:

• R1 — Identity owned by Graph.
• R2 — Mutability bright-line; Lake = immutable, Graph = mutable.
• R3 — Topology owned by Graph, exclusively.

Apply R2 first; the first rule that resolves wins.

See also#

• Perception Lake — the immutable-observation sibling layer.
• Graph Model — the node / edge / property data model.
• Persistence & WAL — how Graph mutations become durable.
• Snapshot-Pinned Reads — how a reader sees a consistent point-in-time view across both layers.