# Apeiron AP1 – G29 bounded coupled moving-split background reference

**Updated UTC:** 2026-09-02T20:41:03Z  
**Classification:** `M1_BOUNDED_COUPLED_MOVING_SPLIT_BACKGROUND_REFERENCE_PASS_STAGED_LONG_EXTENSION_OPEN_PHYSICAL_KERNEL_BLOCKED`  
**AP1 status:** ORANGE

The chronology-safe 128-shell state was advanced by a genuinely coupled,
N-parametrized background/mode iteration.  Existing modes remained in the
log-amplitude/Riccati chart.  Every newly resolved mode inherited the same
adiabatic order-0/2/4 state validated by G28 at the moving physical boundary
`q_cut = 0.6 Lambda`; no instantaneous order-0 reset occurred.

## Held-out aggregate

- coupled time-grid background delta: `2.6432169114225527e-11`
- coupled time-grid source gross-relative delta: `4.9894042264208202e-13`
- entry-time quadrature gross-relative delta: `4.9822119353899943e-13`
- UV-tail quadrature gross-relative delta: `2.2655579456434034e-09`
- UV cutoff gross-relative delta: `3.1874584981983385e-15`
- fixed-point source gross-relative closure: `3.3559761085824485e-14`
- Ward residual: `0.0008750230466406364`
- Friedmann residual: `4.0843325553235381e-09`
- independent Raychaudhuri residual: `4.0603436286897413e-09`
- Wronskian error: `1.6653345369377362e-15`

All frozen G29 held-out gates pass.  Four bounded background integrations were
performed across pilot and held-out time-refinement pairs; zero trajectory rows
were promoted to a production curve or seed.

## Boundary

This checkpoint validates only the bounded coupled architecture.  The staged
long-background extension to the present anchor, production tolerances, AP2/AP3,
production curves, observables, and the physical two-time response kernel remain
locked.  No fit or significance is claimed.