From Counts to Observables: The response layer of a finite record substrate, a bridge for physicists, information scientists, and engineers

From Counts to Observables: The response layer of a finite record substrate, a bridge for physicists, information scientists, and engineers. Five executable bridge theorems -- the two-algebra split (records commuting/copyable, responses CTP-organised); the collapse theorem (a latched channel's spectral function is a contact with residue exactly the service count, so every probe observable factorises O = T x r); count rigidity (no anomalous dimension; schemes move the transfer only); the five-front observable ledger (QED, electroweak, CMB, black holes, continuum QCD) with live comparators; and the Born reading law (probabilities as count shares at the latch). Includes an engineering on-ramp (SI-2019 count-rooted units, calibration as response theory, Kalman observability, ratiometric practice) and a quantum-information forward path with five open problems (record capacity, record/response complementarity, latched-sector identifiability, rigidity-optimal codes, device-independent counts). All quantitative claims are asserted by self-checking gates (counts_to_observables_bridge_gate.py, exit 0, 5/5). This record is part of the finite-QEC substrate / It-from-Bit publication refresh.