Exact answers, no map, no mitigation: user-written circuits through a placement-only OS on IBM Heron r2 devices

A user writes, in plain Qiskit, a circuit whose answer is known exactly. A small operating layer (psf-os) places it on an IBM Heron r2 device by translation, without reading any calibration-quality number, adds its own controls to the same job, and runs it with no error mitigation. We report how close the raw answers come and how that is shown. Two points of the report are of use beyond our own numbers. First, an absolute criterion |M - M_exact| <= c is biased in both directions: on 5 November a problem that DIFFERS under c = 0.05 kept 0.82-0.86 of its signal, as much as a problem that AGREES (0.73-0.85), and a small-answer problem AGREES while keeping only 0.73 of its signal. We therefore print the declared verdict first and the retention R = M/M_exact beside it on every row. Second, every number can be checked: answers are sealed by hash before each run, raw counts and job identifiers are committed, and one script re-scores all 13 device results of this paper from the raw counts and finds every number the same. The results: 22 practice circuits on two devices (all 22 READ on both; 19 and 18 AGREE), a daily record from 5 to 7 November (7 runs and one refusal), and IBM's dual-unitary kicked-Ising chain (arXiv:2411.00765) at N = 51 and N = 71 sites, where the raw decay rates agree with cos 2h at all three h (largest |k - cos 2h|: 0.0045 at N = 51, 0.0017 at N = 71) and every depth up to t = 24 (1,715 CZ) is readable. Local failure regions, not problem size, set several outcomes. A correction built from the job's own controls, declared in advance, reduced the error on both devices but did not make the answers agree across problems. No quantum advantage is claimed: every answer here is computed exactly on a classical machine. We acknowledge the use of IBM Quantum services for this work.