13-EFT.WP.Methods.SimStack v1.0 | Preface

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Preface

I. Scope and Objectives

• This volume presents a unified methodology and interface for the hybrid simulation stack (SimStack) that couples continuum approximations (Sea / Density / Tension) with discrete weaving (Threads), and hardens the minimal closed loop from model → execution → release.
• Writing and numbering follow the series convention without exception: subsection titles in bold Roman numerals; bullet lists with “- ”; numbered lists with “1. ”; all inline symbols in backticks; any division/integral/composite operator must be parenthesized with explicit gamma(ell) and d ell.
• The dual arrival-time gauges serve as long-lived cross-volume anchors: T_arr = ( 1 / c_ref ) * ( ∫ n_eff d ell ) and T_arr = ( ∫ ( n_eff / c_ref ) d ell ).
• Reserved numbering ranges for this volume: Postulates P61-*, Minimal Equations S62-*, Metrology flows Mx-6*, Implementation bindings I60-*. Cross-volume citations use the fixed format: “see companion white paper ‘…’ Chapter x S/P/M/I…”.

II. Audience and Reading Path

1. Intended readers
   • Modeling & numerics: focus on kernel coupling, coupled advancement, stability, and error control.
   • Platform & parallelism: focus on scheduling, back-pressure, SLOs, and TS.* observability.
2. Recommended prerequisites
   Core.Terms, Core.Equations, Core.Metrology, Core.DataSpec, Core.Threads, Core.Sea, Core.Density. Reading in catalog order yields a unified gauge set and a closed dependency loop.

III. Numbering Ranges and Cross-Volume Interfaces

• This volume adopts: P61-* / S62-* / Mx-6* / I60-*. Cross-volume references must preserve symbol and unit consistency.
• Time base and mapping: internally measure delay/jitter using tau_mono; publish externally on ts. The linear clock model ts_i(t) = alpha_i * tau_mono + beta_i + epsilon_i(t) is the default calibration frame.
• When arrival time is used for temporal calibration, compute both gauges in parallel and report the discrepancy
  delta_form = | ( 1 / c_ref ) * ( ∫ n_eff d ell ) - ( ∫ ( n_eff / c_ref ) d ell ) |,
  and record gamma(ell), d ell, c_ref, n_eff.

IV. Unified Definitions and Symbols (Preface Hardening)

• Path and measure
  gamma(ell): piecewise-C1 path with ell ∈ [0, L_gamma]; d ell is the path measure; L_gamma = ( ∫_gamma 1 d ell ); path average avg_gamma[f] = ( 1 / L_gamma ) * ( ∫_gamma f d ell ).
• Arrival time (unified template)
  Definition: T_arr(gamma) def= ( ∫_gamma ( n_eff / c_ref ) d ell ); constant-out form: T_arr(gamma) = ( 1 / c_ref ) * ( ∫_gamma n_eff d ell ).
• Time axes
  tau_mono (internal monotonic clock); ts (UTC publication). They satisfy a linear mapping and carry offset/skew/jitter estimates.
• Collision mandates
  T_fil (tension) vs. T_trans (transmission coefficient) must remain distinct; n (number density) vs. n_eff (effective refractive index) must remain distinct.
• Explicit measure
  Every integral must declare its domain and measure, e.g., ( ∫_Omega p(x) dx ) = 1, ( ∫_V rho(x,t) dV ), ( ∫_{gamma(ell)} a(ell) d ell ).

V. Disambiguation Rules for Mathematical Expressions (Enforced Herein)

• Writing discipline: wrap inline symbols in backticks; parenthesize any expression with division/integral/composite operators and explicitly declare gamma(ell) and d ell; always list both arrival-time gauges.
• Dimensional conservation: validate with check_dim(expr), enforcing dim( ( n_eff / c_ref ) * d ell ) = [T]; using n for n_eff is forbidden.
• Time-axis alignment: measure delay/jitter/retry on tau_mono; publish on ts. For cross-device causal (hb) comparisons, map events to tau_mono first.
• Dual-gauge discrepancy: any T_arr-based calibration or fit must report delta_form and persist it in the manifest.

VI. SimStack Method Families and Stack Layers

1. Layers and artifacts
   • Continuum kernel: pluggable physics for n_eff(x,t), rho(x,t), and spectral quantities S_xx(f).
   • Discrete weaving: Thread/Actor, execution graph G=(V,E), hb and back-pressure bp.
   • Coupler: cross-domain exchange with consistency/idempotency contracts.
   • Execution & observability: scheduling, quotas, TS.* indicators.
2. Prototype family (preview, I60-*)
   • I60-1 couple_fields(...) — couple continuum kernels to discrete nets.
   • I60-2 exchange_packets(...) — exchange wave packets/flux/events by message semantics.
   • I60-3 advance_dt(...) — stability and step-size control.
   • I60-4 calibrate_arrival_time(...) — compute both gauges and output delta_form.
   • I60-5 emit_metrics(...) — emit TS.* for SLOs and regression.
   • Concurrency semantics, queues, and bp strictly align with Core.Threads runtime and its contract test matrix.

VII. Minimal Data & Manifest Gauges

1. Required persisted fields
   • measure / units / support / norm (domain, measure, units, normalization/conservation status).
   • If arrival time is present: T_arr.{gamma, d ell, c_ref, n_eff, delta_form}.
   • Time base: alignment of ts and tau_mono plus uncertainty.
2. Acquisition & spectral manifests must adhere to window and ENBW gauges and be included when applicable.

VIII. Quality Gates and Calibration Flows (Synopsis)

• Mx-61 Time-base & arrival-time calibration
  Estimate alpha/beta via the linear clock model; if T_arr is used, record both gauges and delta_form.
• Mx-62 Conservation/normalization checks
  Only after eps_norm and eps_mass meet their gates may artifacts be published.

IX. Cross-References and Dependencies

• Concurrency concepts and metrics inherit from Core.Threads; timing and hb semantics follow that volume’s Chapter 4. See companion white paper Core.Threads Chapter 4 P74-/S74-/Mx-*.
• Arrival-time, time-base, and window gauges follow Core.Sea; if T_arr is used, complete tau_mono alignment before spectral estimation or fitting. See Core.Sea Chapter 3 P83-/S83-.
• Measure, support, and unit norms follow Core.Density; rigorously enforce “explicit measure” and manifest minimal fields. See Core.Density Chapter 1 P91-* / Chapter 2 S92-*.

X. Versioning and Compliance

• From v1.0, core gauges and interfaces are frozen. Any incremental revision must be backward compatible and recorded in the appendices with diffs and migration guidance (repro experiments and pipeline compliance follow Methods.Repro).

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Unified Notation Roster (Preface Anchor for Reuse)

• Time & path: tau_mono, ts, gamma(ell), d ell, T_arr, c_ref, n_eff(x,t).
• Fields & densities: rho(x,t), S_xx(f); explicit measures dV/dS/d ell.
• Concurrency & execution: G=(V,E), hb, bp, T_make(G), TS.sli.*.
• Collision names & gauges: T_fil vs T_trans; n vs n_eff (strict isolation).

Two-Gauge Unified Example (Preface Anchor)

• Constant-out: T_arr = ( 1 / c_ref ) * ( ∫ n_eff d ell )
• General: T_arr = ( ∫ ( n_eff / c_ref ) d ell )
• Discrepancy: delta_form = | ( 1 / c_ref ) * ( ∫ n_eff d ell ) - ( ∫ ( n_eff / c_ref ) d ell ) |.

Forbidden Mixing & Writing Discipline (Mandatory)

• Wherever T_fil and T_trans, or n and n_eff appear, apply strict isolation rules. All formulas, symbols, and definitions must be in English plain text.