Emit Prophet Trust Chain boot and device verification evidence

[mdheller]

Context

SocioProphet/prophet-platform now carries docs/standards/PROPHET_TRUST_CHAIN_V0.md and the first trust-chain admission fixtures.

SourceOS Boot owns boot, recovery, rollback, secure live provisioning, BootReleaseSet validation, and device verification evidence. This issue implements the SourceOS Boot slice of Prophet Trust Chain.

Target

Bind BootReleaseSet and boot/recovery operations to trust-chain evidence so production admission can start below the runtime layer.

The first path should cover:

BootReleaseSet
  -> boot manifest hash
  -> selected release set
  -> boot mode
  -> verification result
  -> device claim
  -> rollback/recovery posture
  -> trust-chain evidence refs

Acceptance criteria

• Add or extend a boot/recovery evidence fixture with device claim, manifest hash, boot mode, selected release set, verification result, and rollback/recovery posture.
• Add a valid example where boot verification evidence can be referenced by Prophet Platform admission.
• Add a blocked example where missing manifest verification or failed device claim prevents admission.
• Existing validation tooling covers the examples.
• Docs reference SocioProphet/prophet-platform/docs/standards/PROPHET_TRUST_CHAIN_V0.md.

Non-goals

• Do not implement full secure boot across every hardware target in this tranche.
• Do not claim production hardware certification from fixtures alone.
• Do not mutate live boot entries without a separate implementation plan and safety review.

[mdheller]

Implementation pass landed for the Prophet Trust Chain boot/device verification slice.

Commits:

• 7b9b2ae7653b3e7d51613cc26357b71a4d6ff722 — added schemas/trust-chain-boot-verification-evidence.v0.1.schema.json.
• 6370d04e430919026b60173aee3bbcd4cd26ad81 — added valid boot verification evidence fixture.
• 53920ab0008f0e0a99dd183d51d154e6abe69a05 — added blocked boot verification evidence fixture.
• 014af1b1161182a08e91726099050783937c63a0 — added src/sourceos_boot/validate_trust_chain_boot_verification.py.
• ffb48c5cde687f51e9bce28cf35dab53bd742641 — wired validate-trust-chain-boot-verification into the Makefile validation path.
• 5937e33564b4f4d725829e6f82b8bcadf5adb319 — added pytest coverage in tests/test_trust_chain_boot_verification.py.
• bdc2239d7c7e5bc58dfba7deed91a635bf91e535 — documented the Trust Chain boot/device verification lane in the README.

Implemented acceptance coverage:

• Machine-readable Trust Chain boot verification schema exists.
• Valid fixture binds BootReleaseSet to verified device claim, manifest hash, selected release set, boot mode, verification result, attestation ref, rollback/recovery posture, policy profile, admission decision, and runtime receipt.
• Blocked fixture proves boot/install admission fails closed when device claim or manifest verification evidence is missing.
• Validator enforces verified records require verified device claim, claim ref, manifest hash, passing verification result, attestation ref, Trust Chain refs, and boot/install allow effects.
• Validator enforces blocked records deny boot/install, require repair and human review, and preserve remediation authority.
• Makefile now includes validate-trust-chain-boot-verification in validate.
• README links back to the Prophet Platform standard, admission contract, and implementation map.

Boundary preserved: SourceOS Boot records boot/device verification evidence. It does not certify production hardware by itself, mutate live boot entries in this tranche, own package/runtime distribution, replace Lattice Forge runtime evidence, replace Policy Fabric policy profiles, replace AgentPlane execution evidence, or replace Prophet Platform admission composition.

Status: functionally complete pending CI validation and review changes.