Extract, Draft, Sign: Regen-Safe Lanes for AI Docs

A regenerated README often looks like progress. The install block is tighter. A stale caption disappears. Then a reviewer finds that the same commit also rewrote the security contact, dropped two SLO numbers, and turned a retention rule into a hedge. The model did not sneak those edits. It treated the file as one string. Regeneration without lanes will keep doing that. This article proposes a split you can check in CI: extract , draft , and sign . A model may write only the draft lane. Deterministic tools own extract. A named human owns sign. The checker below is sample code, not a production audit and not a legal control. The failure mode is whole-file regen Most doc pipelines still do this: Concatenate the old markdown. Ask a model to update it for the latest API. Overwrite the path. That loop is cheap. It is also how a metaphor and a contractual sentence become the same token stream. If the process cannot name which paragraphs are allowed to change, every regen is a silent policy edit. A useful split is not "AI versus human" as a vibe. It is three writers with three failure costs. Extract fails when a dump script is stale. Draft fails when the prose is wrong or vague. Sign fails when a promise moves without a person noticing. Decision table: who is allowed to write Doc fragment Source of truth Lane Model may draft? Human must sign? CLI flags, env vars, HTTP routes --help , OpenAPI, code extract No Own the extractor Samples that must compile tests / doctest extract No Own the test Install narrative, "why this shape" none draft Yes Review Architecture walkthrough none draft Yes Review Security contact, threat-model claims policy sign No Yes SLO numbers, error budgets SRE / contract sign No Yes License, embargo, export notes legal sign No Yes Changelog dates and SHAs git extract No Own git log "We never store X" legal / security sign No Yes Analogies, diagrams-as-prose none draft Yes Review If wrong wording can page someone, leak PII, or change a customer promise, i