test: integration tests for NIP-04 Encrypted Direct Messages (Kind 4) #506

Summary

NIP-04 encrypted direct messages (kind 4) are listed in the relay's supported NIPs but have no integration test coverage. The flow differs from kind 1 in that messages are targeted to a recipient via a p tag, and access control (if any) hinges on that tag.

What to test

• Alice publishes a kind 4 event with Bob's pubkey in a p tag → accepted and stored
• Alice can retrieve her sent DM by event ID
• Bob subscribes with a filter for #p matching his pubkey → receives Alice's DM
• A third party (Charlie) subscribed to Bob's pubkey filter should not receive the encrypted content differently (relay stores and forwards the ciphertext as-is)
• Duplicate kind 4 event submission → returns duplicate: command result

Relevant code

• src/constants/base.ts — EventKinds.ENCRYPTED_DIRECT_MESSAGE
• src/handlers/event-strategies/default-event-strategy.ts

Suggested location

test/integration/features/nip-04/nip-04.feature