proof-scaffold 0.0.8

A layered, sanity-checked scaffold for building modular Metamath artifacts.

ProofScaffold

A layered, sanity-checked scaffold for building modular Metamath artifacts.

ProofScaffold treats Python as the builder (compiler/linker) and Metamath as the verifier (semantic authority). It follows a Transient Monolith strategy: build modular packages into IR (LIR), then concatenate them into an ephemeral .mm file for verification by one or more verifiers (e.g. metamath-exe, mmverify, metamath-knife).

Install: pip install proof-scaffold
Import: import skfd
CLI: python -m skfd.cli ... (or skfd ... if installed)

Note: the PyPI distribution name is proof-scaffold, while the Python import package is skfd.

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Why ProofScaffold

If you are maintaining a growing Metamath codebase, ProofScaffold aims to make it:

• Modular by construction: proofs live in explicit Python packages with declared dependencies.
• Traceable: symbol interning + origin tracking keep generated artifacts debuggable.
• Sanity-checked: the builder can enforce invariants before invoking verifiers.
• Verifier-agnostic: run multiple verifiers consistently via a single config (.skfd).
• Deterministic: canonical builds enable stable caching and reproducible verification.

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Unicode authoring, canonical builds

Proofs are authored in Unicode (e.g. ¬, →, ∨, ∧) for readability. Internally, the builder canonicalizes formulas into a stable ASCII representation for IR, caching, and verifier interop.

Canonicalization is deterministic and whitespace-insensitive: the same formula always maps to the same canonical token stream.

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Quickstart

pip install proof-scaffold
mkdir my-proofs
cd my-proofs
python -m skfd.cli init-pkg my-proofs
python -m skfd.cli doctor check
python -m skfd.cli verify my-proofs

This will:

1. Discover all build.py files under src/.
2. Topologically sort packages by declared deps.
3. Build each package in memory (LIR).
4. Emit target/<project-name>_full.mm (Transient Monolith).
5. Run configured verifiers (if available).

Tip: my-proofs is a project name (from pyproject.toml → [project].name). verify <project-name> targets that project’s build unit (and its dependency closure).

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Example: a tiny proof script

from typing import Any


def prove_modus_tollens(sys: Any) -> Any:
    """
    Modus Tollens: φ → ψ, ¬ψ ⊢ ¬φ
    """
    from skfd.proof import ProofBuilder

    lb = ProofBuilder(sys, "modus_tollens")

    h1 = lb.hyp("h1", "φ → ψ")
    h2 = lb.hyp("h2", "¬ ψ")

    s1 = lb.ref("s1", "( φ → ψ ) -> ( ¬ ψ → ¬ φ )", ref="con3", note="con3")
    s2 = lb.mp("s2", h1, s1, note="MP h1, s1")
    s3 = lb.mp("s3", h2, s2, note="MP h2, s2")

    return lb.build(s3)

Verify:

python -m skfd.cli verify <project-name>

For a larger proof that showcases lifting/distribution patterns and origin tracking, see examples/.

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Concepts and layout

Terminology

• Project: a ProofScaffold workspace root (contains pyproject.toml + src/).
• Build unit: what skfd verify targets; named by pyproject.toml → [project].name.
• Package (Python): the import package under src/<name>/ (often <project-name> with - → _).
• Driver: resolves deps, builds packages, emits transient monolith .mm.
• LIR: the builder’s intermediate representation emitted by packages.

Key components

1) Generic Logic Driver (skfd.driver)

Manages the build lifecycle of logic packages.

• Explicit dependencies: packages declare deps in build.py (e.g. metamath-prelude, metamath-logic).
• No implicit globals: dependencies are injected by the driver.
• Primary command: python -m skfd.cli verify <project-name>

2) Builder API (skfd.builder)

A fluent Python API for constructing Metamath databases.

• Atomic LIR generation.
• Symbol interning + origin tracking (for debuggability).

3) Engineering standards (AGENT.md)

CI-enforced discipline:

• Ruff (lint/format)
• MyPy (strict typing)
• Pytest

See AGENT.md for the contributor protocol.

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Verifier configuration (.skfd)

ProofScaffold can run multiple verifiers in a single verify pass. The active set is controlled by .skfd.

Minimal config (single verifier)

Example: only metamath-exe (adapt command to your environment)

active = ["metamath-exe"]

[verifiers.metamath-exe]
command = "metamath"
args = ["target/<project-name>_full.mm"]

Advanced config (multiple verifiers + shims)

Example (mmverify + metamath-knife + metamath-exe + shim):

active = ["mmverify", "metamath-knife", "metamath-exe"]

[verifiers.metamath-knife]
command = "../metamath-knife/target/release/metamath-knife"
args = ["--verify"]

[verifiers.metamath-exe]
command = "/usr/bin/env"
args = [
  "METAMATH_BIN=../metamath-exe/src/metamath",
  "./.venv/bin/python",
  "./verifier/shims/metamath.py"
]

Environment check:

python -m skfd.cli doctor check

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Usage

Dev mode vs. user mode

User mode (installed via PyPI)

• Dependencies are installed packages; no PYTHONPATH needed.
• .skfd can be minimal and extended only if desired.
• Typical usage: python -m skfd.cli verify <project-name>.

Dev mode (multi-repo / local path deps)

• Repos may live side-by-side; dependencies can be pulled via local path (e.g. uv sources).
• You may need PYTHONPATH depending on your workspace layout.
• .skfd often points to local binaries and shims (multi-verifier runs).

Initialize a project

Package mode: creates src/ + pyproject.toml + .skfd

mkdir my-proofs
cd my-proofs
python -m skfd.cli init-pkg my-proofs

Standalone proof script: creates my_proof.py (no src/)

python -m skfd.cli init-proof my_proof.py

Build & verify a project

python -m skfd.cli verify <project-name>

verify checks the generated transient monolith. If a package exposes a larger authoring-facing theorem registry than it emits in build(ctx), validate that registry in the package's own tests:

from skfd.proof import assert_valid_proof_registry


def test_public_proof_registry() -> None:
    system = System.make(interner=interner, names=names)

    assert_valid_proof_registry(
        system=system,
        constructors=SETMM_TO_HILBERT_LEMMAS,
        axioms=system.compile_axioms(),
        reserved={"wi", "wn", "wa", "mp"},
    )

This catches dangling lb.ref(..., ref="...") labels, constructor-time proof errors, self-references, and dependency cycles before verifier invocation.

Packages can also declare their intended proof surface during build(ctx):

def build(ctx: BuildContextV2) -> None:
    ...
    ctx.coverage.declare_registry("hilbert", SETMM_TO_HILBERT_LEMMAS)
    ctx.coverage.require_all_declared_verified()

Then run:

python -m skfd.cli verify --coverage declared <project-name>

--coverage declared fails if any declared label is missing from the emitted verification monolith. Packages without coverage declarations keep the existing behavior and report that coverage is limited to the emitted monolith.

Browse theorem dependency chains (local web)

python -m skfd.cli serve <project-name> --port 8000

Then open http://127.0.0.1:8000/ and search/click assertions to inspect direct and reverse dependencies.

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Run tests:

pytest

If you use uv:

uv run pytest

See CONTRIBUTING.md for development workflow and contribution guidelines.

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Documentation

Start here:

• projects/009-logic_driver.md — driver design, IR, and the Transient Monolith strategy.
• examples/ — minimal and larger proof examples.
• src/skfd/ — core toolchain implementation.

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License

See LICENSE.