> ## Documentation Index
> Fetch the complete documentation index at: https://docs.langstate.com/llms.txt
> Use this file to discover all available pages before exploring further.

# DAH-backed storage

> Internal directed acyclic hypergraph mechanics behind LangState state.

`State` stores fields in a `DirectedAcyclicHypergraph` (DAH). The DAH generalizes a directed acyclic graph by allowing a hyperedge with multiple source nodes and one target node.

## Node indexes

Each node contains:

* a generated UUID used for internal identity;
* a string path used for public lookup;
* an optional payload; and
* incoming hyperedges plus reverse dependent links.

The graph maintains both a UUID-to-node map and a path-to-UUID secondary index. `State.get_field()` and other public state methods address nodes by path.

## Hyperedge semantics

A target may have multiple incoming hyperedges. Readiness follows an **OR of AND groups**: a target is ready when any incoming hyperedge has all of its sources satisfied. Cycle checks treat each source-to-target relationship as a directed edge for ordering.

Single-parent field hierarchy uses one-source hyperedges. Callers can reach the underlying structure with `state.get_dah()` when they need multi-source relationships:

```python theme={null}
from core.state.canonical.state import CanonicalState

state = CanonicalState()
graph = state.get_dah()

graph.add_node("registrant.validated", True)
graph.add_node("event.selected", True)
graph.add_hyperedge(
    ["registrant.validated", "event.selected"],
    "registration.ready",
)
```

## State integration

`set_field()` automatically creates parent nodes and path-segment dependencies. `copy()` recreates nodes and hyperedges in a new state; interpretive state deep-copies its Pydantic field payloads.

`remove_field()` removes the selected node and incident hyperedges. It does not promise a recursive subtree delete, so remove descendant paths explicitly if that is the desired application behavior.

## Stability boundary

DAH classes are importable source modules and have direct unit coverage, but they are internal infrastructure within a source-only alpha. Prefer the `State` methods for application code unless the hypergraph operations are specifically required and tested by your integration.