Nostr Kinds — Design and Schema

Load this skill when:

• Minting a new event kind for a Ditto feature.
• Extending an existing NIP with new tags.
• Deciding whether an existing NIP covers a use case or whether a custom kind is warranted.
• Documenting a custom kind or extension in NIP.md.

Not this skill — if an existing NIP/kind covers your use case and you only need to render it in Ditto's UI, use the nostr-kind-rendering skill instead.

Choosing Between Existing NIPs and Custom Kinds

1. Thorough NIP review first. Browse the NIP index, then read candidate NIPs in detail. The goal is to find the closest existing solution.
2. Prefer extending existing NIPs over creating custom kinds, even at the cost of minor schema compromises. Custom kinds fragment the ecosystem.
3. When an existing NIP is close but not perfect, use its kind as the base and add domain-specific tags. Document the extension in NIP.md.
4. Only mint a new kind when no existing NIP covers the core functionality, the data structure is fundamentally different, or the use case requires different storage characteristics (regular vs. replaceable vs. addressable).
5. If a tool to generate a new kind number is available, you MUST call it. Never pick an arbitrary number.
6. Custom kinds MUST include a NIP-31 alt tag with a human-readable description of the event's purpose.

Example decision:

Need: Equipment marketplace for farmers
Options:
  1. NIP-15 (Marketplace)   — too structured for peer-to-peer sales
  2. NIP-99 (Classifieds)   — good fit, extensible with farming tags
  3. Custom kind            — perfect fit, no interoperability

Decision: NIP-99 + farming-specific tags.

Kind Ranges

An event's kind number determines storage semantics:

• Regular (1000 ≤ kind < 10000) — stored permanently by relays. Notes, articles, etc.
• Replaceable (10000 ≤ kind < 20000) — only the latest event per pubkey+kind is kept. Profile metadata, contact lists, mute lists.
• Addressable (30000 ≤ kind < 40000) — identified by pubkey+kind+d-tag; only the latest per combo is kept. Long-form content, products, definitions.

Kinds below 1000 are "legacy"; storage is per-kind (e.g. kind 1 is regular, kind 3 is replaceable).

Tag Design Principles

• Kind = schema, tags = semantics. Don't mint a new kind just to represent a different category of the same data.
• Relays only index single-letter tags. Use t for categories so filters like '#t': ['electronics'] work at the relay level. Multi-letter tags (product_type, etc.) force inefficient client-side filtering.
• Filter at the relay, not in JavaScript:

```ts // ❌ Fetch everything, filter locally const events = await nostr.query([{ kinds: [30402] }]); const filtered = events.filter((e) => hasTag(e, 'product_type', 'electronics'));

// ✅ Filter at the relay const events = await nostr.query([{ kinds: [30402], '#t': ['electronics'] }]); ```

• For Ditto-specific niches (community apps, regional variants), tag events with a t value and query on it. Don't do this for generic platforms — it would silo content.

Content vs. Tags

• content — large freeform text or existing industry-standard JSON (GeoJSON, FHIR, Tiled maps). Kind 0 is the one exception where structured JSON goes in content.
• Tags — queryable metadata, structured data, anything you might filter on.
• Empty content is fine. content: "" is idiomatic for tag-only events.
• If you need to filter by a field, it must be a tag — relays don't index content.

// ✅ Queryable
{ "kind": 30402, "content": "",
  "tags": [["d", "product-123"], ["title", "Camera"], ["price", "250"], ["t", "photography"]] }

// ❌ Structured data buried in content
{ "kind": 30402, "content": "{\"title\":\"Camera\",\"price\":250}", "tags": [["d", "product-123"]] }

NIP.md

NIP.md documents Ditto's custom kinds and any extensions to existing NIPs. Whenever you mint a new kind or change a custom schema, create or update NIP.md with the tag list, content format, and intended usage. If a kind you add is effectively the same shape as an existing NIP, note the NIP reference rather than duplicating the spec.

Standard NIPs (like NIP-84 Highlights, NIP-23 Articles) do not go in NIP.md — only Ditto-custom kinds and Ditto-specific extensions.

After Designing — What's Next?

Once you've settled on a kind number and tag shape, you still need to render it in Ditto's UI. Load the nostr-kind-rendering skill for the full multi-location registration checklist (feed cards, detail pages, embedded previews, kind-label maps, notifications, feed-toggle registration).