# ADR-022: Composite foreign keys for node references

## Status

Accepted

## Context

Edges reference source and target nodes. A simple `sourceNodeId` FK would work but doesn't capture the composite key model.

## Decision

Edges reference nodes via composite FKs: `(graphId, sourceNodeKey) → (nodes.graphId, nodes.key)`. This ensures referential integrity within a graph and cascades node deletions to connected edges.

## Consequences

- Deleting a node cascades to all its edges
- Edges cannot reference nodes in a different graph
- Composite FKs match the metagraph identity model `(graphId, key)`

## References

- [sqlite-host.md](../sqlite-host.md)