The convention is that a decision record is never amended in place: when a decision changes, a new record is minted and the old one is marked superseded by it, so the decision history stays legible and a reader of the old record is pointed forward rather than misled. Nothing in the tree states it. The typed-link vocabulary is recorded in .abcd/development/principles/decompose-before-filing.md as supersedes / reverses / duplicates / refines, and adr-58 and adr-2609021016286571 demonstrate the shape in practice, but the rule that amendment is not an option is carried only by example, so an agent or a contributor reaching for the smaller edit has nothing to read that refuses it. The gap surfaced when a relocation of the transcript corpus made adr-29's stated location wrong and the question of amend-versus-supersede had to be asked rather than looked up. Fix: state the rule where the conventions live, in the AGENTS.md decisions section or as a principle under .abcd/development/principles/, naming the two typed links and the one edit a superseded record does receive, and say why: an amended record erases the fact that the decision changed, which is the thing the record family exists to preserve. Detector: the conventions text names the rule and a docs test or record-lint rule refuses a decisions section that omits it, or at minimum the rule is present where a contributor reading AGENTS.md would meet it before editing a record.

The convention is that a decision record is never amended in place: when a decision changes, a new record is minted and the old one is marked superseded by it, so the decision history stays legible and a reader of the old record is pointed forward rather than misled. Nothing in the tree states it. The typed-link vocabulary is recorded in .abcd/development/principles/decompose-before-filing.md as supersedes / reverses / duplicates / refines, and adr-58 and adr-2609021016286571 demonstrate the shape in practice, but the rule that amendment is not an option is carried only by example, so an agent or a contributor reaching for the smaller edit has nothing to read that refuses it. The gap surfaced when a relocation of the transcript corpus made adr-29's stated location wrong and the question of amend-versus-supersede had to be asked rather than looked up. Fix: state the rule where the conventions live, in the AGENTS.md decisions section or as a principle under .abcd/development/principles/, naming the two typed links and the one edit a superseded record does receive, and say why: an amended record erases the fact that the decision changed, which is the thing the record family exists to preserve. Detector: the conventions text names the rule and a docs test or record-lint rule refuses a decisions section that omits it, or at minimum the rule is present where a contributor reading AGENTS.md would meet it before editing a record.

Remedy grounds (2026-09-29)

• Both answers keep the old decision text intact and differ only in whether a partial change has its own link word, which is the fork adr-2609231048308186 exposed.
• SOTA check: Nygard's original ADR post (https://www.cognitect.com/blog/2011/11/15/documenting-architecture-decisions, read 2026-09-29) keeps a reversed decision and marks it superseded; adr-tools (https://github.com/npryce/adr-tools, src/adr-new, read 2026-09-29) supports both a supersede flag and an Amends/Amended by link, so both answers have prior art.
• Rejected: editing the accepted decision text in place, which both sources and the record refuse.