Source: extracted verbatim from the Engineering PRD, docs/prd/11-performance-ledger.md (REQ-DOC-004). From M0 onward this file is the canonical, living ADR record; status changes happen here and in the index, with the PRD text remaining the historical record.
Status: Accepted.
Context: Charter Surface D promises machine-readable, independently versioned results; disputes must be answerable from artifacts alone (Charter §12).
Alternatives: (1) database/service — rejected: infrastructure burden, repo-external trust; (2) one growing JSON/CSV file — rejected: merge conflicts, no per-run manifests; (3) append-only per-run directories with schema-validated JSON committed via PR (selected): reviewable diffs, git provenance, zero infrastructure.
Consequences: repo size grows with runs (raw JSON retained) — acceptable at v1 scale (~tens of MB); revisit with git-lfs if >200 MB (21).
Reconsideration: result volume or an external dashboard need.