Stage350: Supply-Chain Evidence Enforcement Session Layer

Stage350 adds an enforcement layer on top of Stage349.

It converts the Stage349 bridge result into a supply-chain enforcement session.

What Stage350 Adds

1. CI enforcement for source_git_commit
2. Fail-closed blocking of local-uncommitted in CI
3. Enforcement session generation
4. session_sha256 binding
5. wrap_signature_required and signature_present recording
6. Transparency entry generation
7. previous_hash / entry_hash chain linkage

What Stage350 Does Not Do

Stage350 does not:

• Treat old unsigned SBOMs as if they were signed at the time
• Register entries to external Rekor automatically
• Anchor entries to Bitcoin
• Store real private keys or signing keys in GitHub

Public Evidence

• docs/enforcement/enforcement_session.json
• docs/audit/stage350-transparency-log.json

Safety Boundary

Private core logic, secrets, signing keys, and private evidence are excluded from GitHub.

Decision Model

• accept: evidence is valid enough for enforcement
• warn: local/non-CI issue detected
• block: CI environment detected unsafe supply-chain evidence and failed closed