Gateway Σ‑Halo — Optics‑Only v0: Microbial Phase Sensor for Metric‑Adaptive Guidance (Hypothesis & Protocol)

We release a public, safety‑first optics‑only v0 of Gateway Σ‑Halo: a microbiome‑based bio‑photonicphase sensor (Bio‑Gate) that produces a measurable phase signal (Δφ) under pump–probe excitation (10–100 kHz). The claim is not spacetime warping; it is metric‑adaptive sensing: Δφ tracks weak environmentalgradients (humidity, temperature, E‑field) during short coherence windows and can, in later versions, bias acontroller toward low‑dissipation trajectories. This v0 excludes plasma hardware, field‑autopilot links, andany physiological telemetry. Σ‑Halo plasma and field guidance are deferred to v0+ pending replication ofΔφ and non‑Poisson photon statistics (g²(τ)). We specify acceptance criteria, nulls, PSD/EMI hygiene,pre‑registration, and Zenodo packaging to enable rapid, transparent testing by the community.