Order-of-Magnitude Limits on a Minimal Soft Interacting Dark Energy (IDE) Model

Soft IDE OOM note (bilingual EN/RU), version 1.0. We present a unified phenomenological study of a minimal class of soft interacting dark energy (IDE) models: energy exchange of order ~10% of the cosmic acceleration budget through the proxy Q = β H ρDE, wDE = −1, with β ≈ 0.2. This is a distinct scale from β̂ ≈ 0.015 in an earlier low-z IDE analysis (DOI 10.5281/zenodo.21362179), used here only for comparison. Using order-of-magnitude (OOM) estimates—H(z)+fσ8 (N=34), simplified EG and ISW×galaxy channels, one Reyes data point, and a ballpark ISW proxy—together with a consistency check against the local conformal-like map β→|γ−1| (Cassini), and branches for DM-only coupling and a phenomenological screening factor S, we separate the fluid transfer (Q) from a field-theoretic reading of the same exchange. Results: at β=0.2, Δχ2 ≡ χ2IDE−χ2ΛCDM ≈ 0.84 on the same N=34. Strong exchange (β ≈ 1) is strongly constrained (Δχ2 ≈ 199). ΛCDM remains a consistent baseline on the probes used. A universal scalar coupling without screening is in clear tension with Cassini; DM-only (αb=0) removes this local tension in the setup considered; screened universal coupling requires Smin ≳ 3.3×103 (not a “light” screening window). Files: Soft_IDE_OOM_EN.pdf (primary), Soft_IDE_OOM_RU.pdf, Soft_IDE_OOM_code_data.zip (reproducibility archive). This note does not replace a full Planck+DESI+CLASS analysis.