Searchable Events — the NIP-50 indexing surface

The contract

quartz/src/commonMain/kotlin/com/vitorpamplona/quartz/nip50Search/SearchableEvent.kt:

interface SearchableEvent {
    fun indexableContent(): String
}

One method; marker and extractor in one. An event kind is searchable iff its event class implements this interface and the class is wired into EventFactory (the stores probe searchability by kind through EventFactory.create — an unwired implementor is invisible).

Rules every implementation follows (keep them when adding one):

• Plain text out. Return the human-meaningful fields joined with "\n" (a handful of metadata-ish kinds use " "); no markup stripping is performed — markdown/asciidoc content goes in raw, JSON-content kinds (kind 0 metadata, marketplace stalls, channel info) parse first and join the extracted fields, never the raw JSON.
• Never throw, never null. There is no defensive wrapper at any call site; a throw aborts the insert transaction. Parsed-JSON implementations use ?.let { … } ?: "".
• Only public data. Encrypted content stays out (e.g. kind 30382 contact cards index only the public petname/summary/topics, never the NIP-44 payload).
• Typical shapes: content alone (~33 kinds); listOfNotNull(title(), content); listOfNotNull(title(), summary(), content); lists index title() + description().

The full kind table

references/searchable-kinds.md in this skill holds the authoritative table — every implementor with its kind number, class, and the exact indexableContent() expression (126 concrete classes / 129 kind values as of 2026-08). Diff that file at a version bump to answer "did the searchable set or any kind's indexed text change?".

Notables that surprise people:

• Kind 9735 (zap receipt) indexes the embedded zap request's content (zapRequest?.content.orEmpty()) — receipts are searchable by the zapper's comment.
• Kind 0 / 31990 index many profile fields space-joined (name, about, nip05, lud16, website, picture URL, …).
• Kind 30063 is claimed twice (ReleaseArtifactSetEvent in nip51Lists and the experimental SoftwareReleaseEvent); EventFactory resolves 30063 to ReleaseArtifactSetEvent, so title()\ndescription() is what actually gets indexed — SoftwareReleaseEvent.indexableContent() is dead on the store path.
• Poll kinds (1068, 6969) append each option label on its own line.

MANDATORY maintenance when you touch this surface

Adding SearchableEvent to a kind, removing it, or changing any indexableContent() body:

1. Update references/searchable-kinds.md in the same PR (external search engines — e.g. the Vespa-backed store's SearchExtractors — mirror this table at pin bumps; a silent change ships them stale search results).
2. Remember existing databases don't reindex themselves. Old rows keep their old (or missing) FTS text until IEventStore.reindexFullTextSearch() runs — the KDoc on that method is the contract. App-side, schedule the resumable overload after shipping such a change.
3. New implementors must be registered in EventFactory or the reindex scan and kind pre-filter (FullTextSearchModule.isSearchableKind) will never see them.

Eligibility policy: a kind becomes searchable when it carries human-authored, human-meaningful text (titles, bodies, names, descriptions). Pure-machine kinds (reactions, follow lists, zaps minus their comment, relay lists) stay out to keep the index small.

How the stores consume it

SQLite (nip01Core/store/sqlite/FullTextSearchModule.kt): CREATE VIRTUAL TABLE event_fts USING fts5(content, content='', contentless_delete=1) — contentless, rowid = event_headers.row_id, an AFTER DELETE trigger keeps it in sync. On insert (when FTS is on and not deferred): if (event is SearchableEvent) → bind event.indexableContent() — the only method ever called. Tokenization is entirely SQLite's default FTS5 unicode61; queries are always a bound event_fts MATCH ? (never concatenated), ordered by bm25 rank then created_at DESC. Query-side semantics (relevance ordering, extension stripping, FTS-off behavior, deferred catch-up) are rules STORE-S01…S06 in the event-store-semantics skill.

Filesystem store (jvmMain/.../store/fs/FsIndexer.kt + FsSearchTokenizer.kt): tokenizes indexableContent() itself, approximating unicode61 (split on non-letter/digit, lowercase); the same tokenizer runs on queries so drift cancels.

NIP-50 client side

SearchQuery (nip50Search/SearchQuery.kt) — typed parse of the search filter string into terms + extensions. A whitespace token is an extension iff it looks like lowercasekey:value (the value not starting with //, so URLs stay free text); duplicate keys keep the last; unknown extensions are preserved (extension(key)). Typed accessors: includeSpam, domain, language, sentiment, nsfw. stripExtensions() / Filter.strippingSearchExtensions() is the bridge the built-in stores use — unsupported extensions are ignored (NIP-50), so an extensions-only search collapses to an unconstrained query, never match-nothing. A server-side store that implements its own extensions (observer:, sort:rank, …) receives the raw string (see the IEventStore KDoc) and should parse with SearchQuery.parse so its syntax stays compatible with what clients send.

SearchRelayListEvent — kind 10007, the user's search-relay list (NIP-51-style, public tags + NIP-44 private tags; not a SearchableEvent itself). Client consumption: commons/.../actions/SearchActions.kt, bootstrap defaults in commons/.../account/AccountBootstrapEvents.kt.

Don't confuse it with commons/.../commons/search/SearchQuery.kt — an app-level local-feed query model (authors/kinds/hashtags/or-terms), unrelated to the NIP-50 wire string.

Tests (executable spec)

• commonTest/.../nip50Search/SearchQueryTest.kt — the extension grammar, token by token.
• commonTest/.../store/sqlite/SearchTest.kt — per-kind indexing (kind 0 profile fields, 40/41 channel JSON, 31924/30617), extension-token ignoring, reindex/resumable-reindex, FTS cleanup on replaceable rotation.
• commonTest/.../store/sqlite/SearchRelevanceOrderTest.kt — bm25-before-recency ordering, limit-after-score, multi-filter rank union.
• commonTest/.../store/sqlite/NoFullTextSearchTest.kt — FTS-off contract.
• jvmTest/.../store/fs/FsSearchTest.kt — tokenizer parity for the filesystem store.