This is a tracking issue for creating a Build Level 4. Build L4 will likely cover some notion of the completeness of the provenance, e.g. that the resolvedDependencies are complete in SLSA Provenance format. This is based on discussions and v0.1, but nothing has been decided yet.

Workstream shepherd: David A Wheeler (@david-a-wheeler)

Related: We might want to merge with #975 (hardware attested builds) and/or #985 (build platform operations track) as discussed in #975 (comment).

Sub-issues:

• Semantic equivalency, reproducible builds, and a new "verifiable build" track #873
• Unique builder.id for SLSA Build > L3 #849
• TODO: add more issues if any