Cross-pad refrac / parent-child depletion coupling
Research-grade — validation in progress.
A stored depletion state — depleted parent wells on OTHER pads with drawdown, drainage radius, cooling, and elapsed production time — is turned into one signed Δσ per stage through the Phase-11 poroelastic + thermoelastic kernels (`src/lib/stageParallel/depletionField.ts` over `depletionStress.ts`). VERIFIED FIDELITY TIERS: `analytic` is the instant steady stress-relief superposition, while `history-coupled` runs the transient line-source solve from each parent's stored rate-versus-time history (Theis superposition in space and time, bounded by initial reservoir pressure). Depletion (ΔP < 0) and cooling (ΔT < 0) return a NEGATIVE Δσ (stress relief → wider, longer stages), the opposite sign of a stress shadow; an empty or disabled state returns exactly zeros so 'no depletion reduces to today's answer' holds byte for byte. Reproducibility is the point of the state object: it is normalised and sorted before use, and `depletionStateHash` / `depletionPhysicsHash` fingerprints are written into every export. Tier-aware receipts stamp `depletion_fidelity=<analytic|history-coupled>` beside the state and physics hashes. Governance layer on `/pad-parallel`: materiality warnings, per-stage Δσ diagnostics, coupling-impact CSV receipt (19 columns), input diff with one-at-a-time psi attribution + stage impact waterfall, selective sync with preview/undo/conflict detection, cross-pad consistency check with auto-align, divergence override with logged acknowledgement, run history, portable `.wbg.depletionState` envelopes, and an append-only sync audit trail with a combined receipt.
The analytic tier remains a steady superposition, while the history-coupled tier already honours stored parent production histories. Next ship: derive the depletion state directly from a `compositionalBlackOil3P` parent history (or ingested production data) instead of user-declared drawdown, and carry the full Δσ tensor (azimuth rotation) into the stage kernel rather than the scalar closure offset.
No phase markers extracted from this row's prose yet.
- No published error band yet — use with engineering judgment.