POST /v1/action

Run one VLA action step (unit-billed, per call)

Robot action route (route_type: action; task #37). Single-shot VLA turn: camera frame(s) + instruction + robot state in, an action-chunk JSON out. Multipart/form-data ONLY; the body crosses to the card VERBATIM (original boundary included — byte integrity is the contract; the dial is POST <lane-base>/action). Accepted form fields — model (required), instruction (REQUIRED non-empty on every row, uniformly — a model whose adapter ignores it still receives it; required→optional is additive later, the reverse breaking), state (required: a JSON-encoded array of numbers; the empty array [] is the legal stateless embodiment; anything else is 400 invalid_param/state), and one or more image FILE parts (the composite payload's own slot name — vision's single-kind payload stays file). Chunk length/horizon is the MODEL's own property, not a request param — horizon, chunk_size, or any other field/query is 400 unknown_param naming it. The 25 MiB multipart family cap applies (413, refused before any connection is made). Metering: unit_type='calls' — ONE billed call per SERVED (2xx) request, request-stamped (never model-reported); usage on every answer is OUR {calls, cost} at 6dp. The response's normalization block — the per-embodiment normalization statistics the card applied — is ROUTE CONTRACT and crosses byte-intact (its content is the card's artifact). An unparseable 2xx body relays verbatim (the row already billed the call). Lane saturation at the provider relays as CLIENT 429 rate_limited (never a 502) with the card's Retry-After forwarded when present, non-rotating, the turn unbilled. Idempotency-Key: accepted and logged, NO replay semantics (§8 route-scope — the multipart family; a retrying client pays twice, documented). The robot models ship UNLISTED at launch (task #37): absent from /v1/models and a plain 404 here until each model's serving lane comes online.

curl -X POST https://api.ironstratum.com/v1/action \
  -H "Authorization: Bearer $IRONSTRATUM_API_KEY" \
  -F model=<model>
  -F instruction=<instruction>
  -F state=<state>
  -F image=@<image>