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Architecture

This document describes the structure of the Structural Explainability (SE) foundation layer and how its components interact.

Overview

Structural Explainability is organized as a layered system:

Formal layer (Lean)
Contract artifacts (JSON)
Operational validation (Python + TOML)
Downstream systems

Each layer has a distinct responsibility.

Core components

1. Formal Contract (se-formal-contract)

Defines:

  • invariants
  • regimes
  • relations
  • proof status

Characteristics:

  • implemented in Lean 4
  • machine-checked where applicable
  • authoritative source of truth

Exports:

data/contract/
  invariant-registry.json
  regime-registry.json
  relation-registry.json
  proof-registry.json

2. Constitution (se-constitution)

Defines:

  • repository classes
  • dependency rules
  • naming patterns
  • manifest schema
  • repository requirements
  • cross-file validation

Consumes:

upstream/se-formal-contract/data/contract/*.json

Responsibilities:

  • enforce structural consistency
  • validate identifiers against formal contract
  • prevent drift across artifacts

Authority model

se-formal-contract
    defines invariants
se-constitution
    enforces usage of invariants
downstream repositories
    implement systems using those constraints
  • authority flows downward only
  • no layer may redefine upstream constructs

Data flow

Lean definitions
lake exe export_contract
JSON artifacts (committed)
submodule (pinned)
Python validation

Key properties:

  • deterministic
  • versioned
  • reproducible

Repository structure (foundation layer)

se-formal-contract/
  SEFormalContract/
    Core / Spec / Conformance modules
  data/contract/

se-constitution/
  data/
    class/
    dependency/
    naming/
    manifest/
    repo/
  src/se_constitution/
    validate/
    types/
  external/
    se-formal-contract/   (submodule)

Module design pattern (Lean)

Each domain is split into:

Core        → definitions and theorems
Spec        → identifiers and requirement shapes
Conformance → identifier-to-theorem trace

This enables:

  • stable identifiers for external systems
  • traceability to formal results
  • separation of concerns

Validation model

Validation occurs in se-constitution:

  1. artifact-level validation
  2. cross-file validation
  3. formal contract binding

Key rule:

dependency-rule principles ⊆ invariant registry

Determinism

The system enforces determinism by:

  • committing generated JSON artifacts
  • pinning the formal contract via submodule
  • avoiding runtime network dependencies

Design constraints

  • formal definitions must not be duplicated
  • identifiers must remain stable once published
  • validation must be reproducible
  • authority must remain one-directional

Failure modes

Contract drift

Lean output ≠ committed JSON

Boundary violation

constitution defines new invariant

Structural inconsistency

missing class / naming / dependency rule