Substrate-Pin

A substrate-pin is the short commit identifier that travels with verified content to identify which version of the producer-side substrate the content was authored against. When a verification page renders a claim about a Spearman ρ value, the footer carries something like Producer-side substrate pinned at axon_neuroautomata 9304dd1. That string is the substrate-pin.

The substrate behind a published claim has lifecycle states. A canonical-numbers pin starts at lifecycle_state: exploratory while it is being authored. It ratchets to stable after Veritas runs its TEST gate and posts a verdict-of-record. The substrate-pin captures both the commit and the lifecycle context at the time the downstream surface was rendered.

Without a substrate-pin, a reader who returns to a page later cannot tell whether the numbers they are reading are the same numbers Veritas attested. The page might have advanced; the substrate might have advanced; the verdict might have been re-issued against a newer substrate. The substrate-pin makes those questions answerable rather than implicit.

Hashing convention

For numerical values, the substrate-pin discipline pairs with content-hash-of-pointed-value: the schema for substrate artifacts records a content-hash for each load-bearing value (e.g., sha256 of the rounded canonical value plus the locator), not a file-SHA over the whole file. File-SHA over-triggers on whitespace and refactoring; content-hash triggers only when the asserted value itself changes. The combination — substrate-pin at commit grain plus content-hash at value grain — lets readers detect substantive drift without false-positives on cosmetic edits.

Substrate-pin advances are a routine event. The discipline that travels with them is single-author-per-artifact: only the substrate-lane can ratchet a lifecycle state or advance a pinned-sha.