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A Thread is the chain of Quote and Response events that forms around a single Listing. Every event in a thread shares the same "h" tag — a deterministic thread ID that ties the conversation back to its root listing and the two parties involved.

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Why Thread IDs?

Listings are replaceable events (kind 31001), meaning the underlying listing event ID can change when a listing is updated. A stable thread ID is needed so that the full quoting history can be queried reliably, even if the root listing has been republished. The thread ID is also party-specific: two different trading partners quoting the same listing will each have their own distinct thread ID. This keeps conversations private and isolated between pairs of participants.

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Thread ID Computation

Given event_id, pubkey1, pubkey2 (all 64-hex, lowercase), where event_id is the root listing event ID and pubkey1/pubkey2 are the two conversation participants:
  1. Validate event_id is non-empty (and 64-hex if enforcing format).
  2. Canonicalize order: pk_lo = min(pubkey1, pubkey2); pk_hi = max(pubkey1, pubkey2) (lexicographic).
  3. Concatenate (no delimiter): raw = event_id + pk_lo + pk_hi.
  4. Hash: sha256(raw); encode hex lowercase → thread_id.
The pubkeys are sorted lexicographically before hashing so the result is identical regardless of which party computes it. Both the listing author and the quoting party will always arrive at the same thread ID for their conversation.