# ADR-021: Edge identity uses consumer-defined keys

## Status

Accepted

## Context

Edges need unique identity within a graph. Auto-generated UUIDs vs consumer-defined keys affect how edges are referenced and updated.

## Decision

Edges use `(graphId, key)` as their unique identity, where `key` is consumer-defined. This matches the metagraph model where consumers control identifiers. For anonymous edges (common in simple graphs), `key` can be auto-generated.

## Consequences

- Consumers can reference edges by meaningful keys (e.g., `"call-001→call-002"`)
- Updates use the consumer's key, not a generated UUID
- Anonymous edges can have null or auto-generated keys

## References

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