invariant-lock

Refuse execution unless the invariant file's hash and version both match the lock. The simplest possible defence against silent drift.

v0.1.0 | MIT License | Zero dependencies

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Why This Exists

Invariants that silently change between versions are not invariants — they are suggestions. Systems that rely on governance rules need a way to prove that those rules have not been quietly modified between the time they were declared and the time they are enforced. invariant-lock binds a hash of the invariants file to an explicit version increment: if either has changed without the other, execution is refused. No gradual drift, no silent regressions, no ambiguity about which rules were in effect when something executed.

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Architecture

  invariants.json  ──┐
                     ├──> compute_sha256()  ──> .lock.json
  version field   ──┘                             │
                                                  │
  Before execution:                               │
                                                  v
  invariants.json  ──┐                    ┌─────────────┐
                     ├──> verify()  ──>   │ hash match? │ ──> OK / LockError
  .lock.json      ──┘                     │ ver match?  │
                                          └─────────────┘

Fail-closed: any mismatch blocks execution. No silent fallbacks.

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Quickstart

git clone https://github.com/LalaSkye/invariant-lock.git
cd invariant-lock
pip install .

# 1. Define your invariants
cat > invariants.json << 'EOF'
{
  "version": "1.0.0",
  "rules": [
    "execution requires explicit authority",
    "halt is a structural capability"
  ]
}
EOF

# 2. Create the lock file
invariant-lock init --invariants invariants.json --lock invariants.lock.json

# 3. Verify before execution (returns 0 on success)
invariant-lock verify --invariants invariants.json --lock invariants.lock.json
# OK

# 4. Tamper with the invariants (without bumping version)
echo '"sneaky_rule"' >> invariants.json

# 5. Verify again — execution refused
invariant-lock verify --invariants invariants.json --lock invariants.lock.json
# LockError: FAIL: invariant drift (sha256 mismatch)

Compute a hash only:

invariant-lock hash --file invariants.json
# sha256:e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855

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Invariants File Format

{
  "version": "1.0.0",
  "rules": [
    "execution requires explicit authority",
    "halt is a structural capability"
  ]
}

The version field is required. All other fields are preserved but not validated. The entire file content is hashed — any byte change produces a different hash.

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Python API

from invariant_lock.core import init_lock, verify, compute_sha256

# Create lock
lock = init_lock("invariants.json", "invariants.lock.json")
# lock == {"version": "1.0.0", "sha256": "e3b0c44..."}

# Verify (returns 'OK' or raises LockError)
result = verify("invariants.json", "invariants.lock.json")
# result == "OK"

# Hash a file
sha = compute_sha256("invariants.json")
# sha == "e3b0c44..."

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Failure Modes

Condition	Error
File not found	LockError: FAIL: file not found
Invalid JSON	LockError: FAIL: invalid JSON
Missing version field	LockError: FAIL: missing required field 'version'
Version mismatch	LockError: FAIL: version mismatch
Content drift (hash)	LockError: FAIL: invariant drift (sha256 mismatch)

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Constraints

• ~130 LOC (implementation + CLI)
• Zero dependencies (stdlib only)
• SHA-256 hashing
• All failures are explicit and typed
• Fail-closed: no silent fallbacks
• Deterministic: same inputs always produce same outputs

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Part of the Execution Boundary Series

Repo	Layer	What It Does
interpretation-boundary-lab	Upstream boundary	10-rule admissibility gate for interpretations
dual-boundary-admissibility-lab	Full corridor	Dual-boundary model with pressure monitoring and C-sector rotation
execution-boundary-lab	Execution boundary	Demonstrates cascading failures without upstream governance
stop-machine	Control primitive	Deterministic three-state stop controller
constraint-workshop	Control primitives	Execution gate, invariant litmus, stop machine
csgr-lab	Measurement	Contracted stability and drift measurement
invariant-lock	Drift prevention	Refuse execution unless version increments
policy-lint	Policy validation	Deterministic linter for governance statements
deterministic-lexicon	Vocabulary	Fixed terms, exact matches, no inference

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License

MIT. See LICENSE.

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Authorship & Rights

All architecture, methods, and system designs in this repository are the original work of Ricky Dean Jones unless otherwise stated. No rights to use, reproduce, or implement are granted without explicit permission beyond the terms of the repository licence.

Author: Ricky Dean Jones Repository owner: LalaSkye Status: Active research / architecture work Part of: Execution Boundary Series — TrinityOS / AlvianTech

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This repository demonstrates deterministic control using standard engineering techniques. No proprietary frameworks or external implementations are used.