kestrel.markets/docs/adr/0057-seat-is-the-platform-unit-post-is-the-role-kestrel-runtime-named.md

A typed, token-efficient language + runtime for agentic trading: agents author bounded plans, the runtime fires them at the tick. CLI + typed library + MCP server.

# OSS-ADR-0057 — "Seat" moves to the platform's sellable unit; the org role renames to Post; the deterministic artifact is named the Kestrel Runtime

**Status:** Accepted (owner-ratified 2026-07-21) · **Paired:** PLAT-ADR-0057
**Amends:** the glossary's Seat entry (vocabulary of ADR-0032); the informal
"engine"/"runtime" naming across docs

## Context

The platform ratified Seat as the sellable unit of Kestrel Terminal (PLAT-ADR-0057,
following a 4-lens naming deliberation): the NYSE two-noun model — the venue stays
singular (the Terminal), a count noun denotes purchased standing at it. English reserves
exactly one noun for "purchased standing at a singular institution," and it is seat;
org usage ("seat tokens", "team seats") had already drifted commercial despite the
reservation. That forces the OSS org role (PM / Strategist / Watcher by deliberation
class) off the word. Separately, the deterministic artifact this repo ships has carried
two ungoverned names — "the engine" (AGENTS.md) and "the runtime" (RUNTIME.md, the
glossary's own prose) — with no glossary entry for either: the same gap class that
hid "Kestrel Terminal".

## Decisions

1. **Post is the org role** (formerly Seat): a role in an agent organization,
   distinguished by its affordable deliberation budget — the exchange floor's own
   split: *you buy a Seat, you work a Post*. A role-noun should fail commercial verb
   frames ("pays for three posts" sounds wrong — correctly). "Seat" is henceforth
   platform vocabulary only (the sellable unit) and is no longer OSS org vocabulary.
   "Role" stays banned (overloaded; reserved platform-side for human RBAC).
2. **The Kestrel Runtime** is the canonical name of the deterministic artifact this
   repo ships: it parses and arms documents, perceives (Frames), fires armed Plans at
   machine speed, models fills, records (Bus), and grades. The determinism boundary IS
   the artifact boundary: fill models, simulation drivers, and renderers are inside it
   (that is why proofs recompute); Agents are outside it (the agent authors; the
   Runtime perceives and executes); the platform's Execution module is outside it (the
   live broker gate the Runtime fires through). Rejected names: unqualified "engine"
   (does not say it runs the language; ambiguous over subsystems), "execution engine"
   (near-collides with the platform's Execution module and names one subsystem of the
   determinism boundary).
3. **Prose hygiene:** Terminal-session prose stops using lowercase "seat" as the
   sitting metaphor (ADR-0055's "session is the seat" phrasing stays historical,
   correct in its own time). The glossary entry opens with "the place a Caller sits
   at" instead.

## Consequences

- Glossary: Seat entry rewritten as Post; new Kestrel Runtime entry; Terminal session
  wording cleaned. AGENTS.md tagline: "the agent authors, the Kestrel Runtime
  perceives and executes."
- Mechanical sweep of role-sense "seat" across OSS docs (ADR-0032/0040 prose, bench
  docs, beads — bead text subject to the scrub discipline): bead `kestrel-l41h`.
- No code-identifier changes are forced by this ADR; identifier renames ride their
  own beads if and when touched.