Session assembly for the opaque seat: bodies, oldest-first, one per line.

This is the discoverable side of the boundary (data). How the query folds it is not.

Build reply posts from a cleaned agent response.

Addresses the last input's sender, preserves any other names on the original wire (e.g. the bus channel), and threads onto the last input's PostId when one is supplied. Empty reply → no posts (quiet).

The caller passes one PostId per input post in the same order. If the ids are missing or misaligned, the reply is still addressed correctly but carries no thread edge (see mkPost) — the honest fallback when a shard does not have access to the stamped log.

Build one synthesis post from a cleaned agent response.

The honest twin of replyPosts for seats that fold every input into their answer: ancestry cites every input's PostId (see synthesis), and the audience is every input's sender and wire name, minus self. Empty reply or no inputs → no posts (quiet).

The caller passes one PostId per input post. If ids are missing the synthesis is still addressed correctly but carries no thread edge.

Opaque evaluate seat: any Text -> IO Text behind list ends.

Commit assembles a session prompt from the input posts; emit is replyPosts of the query result (empty = quiet).

TODO: this generic seat does not have access to stamped log ids, so emitted replies carry no thread edge. Callers that need provenance should use a variant that supplies parent ids.

queryShard parameterised on the reply-to-posts builder.

Opaque synthesis seat: like queryShard, but the emit cites every input's sender as ancestry (synthesisPosts). For seats that fold the whole input into one answer — the honest-provenance twin of queryShard.

TODO: like queryShard, the generic seat has no ids and therefore emits syntheses without thread edges.

Mock seat: reply body is the session prompt (echo).

Demonstrates the living-agent path without a real query.

One closed shard turn: commit ins, emit replies.