One anchored run under a changing load. Same bytes as POST /run_trajectory. The size of the answer follows from the request: about 230 characters for each recorded state, plus the request as it was sent, plus up to 8000 characters for the final state and the seals. A state is recorded at each multiple of record_every and at the last landed step, so 10,000 steps with record_every 1 answer with about 2.3 million characters, and the same steps with record_every 10000 with one recorded state. What keeps it small: a larger record_every; the final state is returned in full whatever is recorded. To read quantities without the frames, add readout: {"quantities": [names the card publishes], "first_past": {"quantity": , "above" or "below": }}. The answer then holds each quantity in decimals at the recorded steps, its minimum and maximum over every landed step with the step, the time (the step times dt_s) and every other listed quantity at that step (at_minimum, at_maximum), and, when asked, the first landed step at which it is past the level, with every other listed quantity there (at_step); with record_every equal to the steps, one state is recorded and the readout gives the extremes of every step. The readout is not part of the sealed request: the run_seal is the seal of the same run without it, the receipt covers it, and at most 8 quantities are read. With from (see its schema) the run starts from a sealed run, and is refused by name when the upstream's seal or a carried value does not hold. A run can be refused in two ways, and they come back differently. A request the door turns away before computing is an error, not a result: its text is one sentence, nothing is sealed, and when the sentence gives the card's name for the refusal the name is in round brackets. A run that starts and is refused part way is a result: outcome is "refused", reject holds the name (null when the cause has none), reject_detail holds the sentence, which ends "The run is sealed to step N. The state at step N+1 was refused and is not sealed.", and the run is sealed up to that last landed step N: steps_landed is N, the count of steps that landed, so the step that was refused is steps_landed + 1. A run that reaches an end its card declares (the first maximum of power of a reactor burst, a capsule's flown parachute deployment, a mission's last day, the end of a record's clock or track) is not refused: outcome is "ended", reject holds the end's name, reject_detail a sentence beginning "Ended" that names the end, and the run is sealed up to its last landed step; describe_card lists a card's declared ends under declared_ends. A sentence that begins "Physical Failure" says the state asked for or reached is outside the card: past a published bound, a limit of the specimen, or the conservation ledger. A sentence that begins "Physical Violation" says the request, or a number in it or computed from it, is not one the engine takes: its shape, a missing or unknown key, the number rule, the step floor or ceiling, a load rule, a size limit, or a value that is not finite. On this open connection one address holds at most 1 physics permit at a time, and a solve, a dataset job and a run of more than 10000 steps are long work, of which 1 runs at a time: a call that finds no permit or no place is answered "Too many concurrent physics tasks." and is sent again; nothing waits. An answer is waited for 60 seconds.