Evidence and Proof · Lesson 04 of 04
Freshness, replay, promotion, and identity
How Ota tracks whether a receipt is still valid (freshness), whether an execution can be replayed, and how semantic identity ties inputs to outputs.
Learning objectives
- Explain what makes a receipt stale
- Describe semantic identity hashing
- Distinguish replay from re-execution
Prerequisites
Freshness, replay, and identity answer different trust questions. Freshness asks whether mutable prerequisites were materialized for this run. Identity asks whether the expected artifact was used. Replay asks whether a reviewed prior output may serve as input authority.
Freshness is per prerequisite
Cold-start verification is derived from runner-authored prerequisite evidence, not a maintainer-authored cold flag. A package cache may assist reconstruction while a clean .venv or node_modules target is still freshly materialized. Unsupported services, databases, and volumes remain unknown until an adapter can provide trustworthy evidence.
Replay requires explicit promotion
Trusted replay follows a one-way authority chain: producer run, recorded attestation, explicit promotion, committed portable authority, and replay consumption. Replay must never select the latest record implicitly or allow a consumer to reach its regeneration producer.
ota receipt --baseline promoted --jsonartifacts: baseline: kind: replay_baseline producer: baseline:generate paths: [test/baseline.json] replay: authority_manifest: replay/baseline.ota.json consumption: read_onlyCanonical terminology
Evidence boundary for this lesson
Establishes
- The worked examples establish the lesson's canonical Ota distinctions for its stated scope.
Does not establish
- Reading the lesson does not validate a repository, execute its tasks, or establish organizational acceptance.
Knowledge check
Can a cache-assisted rebuild still be cold-start verified?
Yes, when Ota verifies an absent or cleared target and materializes the touched prerequisite during this run. Cache assistance is a separate derivation posture.