codex-sync zero-change proof

Date: 2026-08-19 · Executed during the skillferry stage-A build (plan §6 step 7 acceptance).

Baseline (recorded before any skillferry work began)

commit 53c81a4d5f5232e71530359b793a437bf42e6d6d (HEAD)
 M docs/README.md                      (pre-existing, 2 inserted lines)
?? docs/SKILLFERRY_PLAN.md             (planning session artifact)
?? docs/SKILLFERRY_RESEARCH_GPT_2026-08-19.md

Post-build verification

The same three entries, the same HEAD, the same diff — the skillferry build read files from codex-sync (the reusable scripts named in the plan) and wrote nothing back:

53c81a4d5f5232e71530359b793a437bf42e6d6d
 M docs/README.md
?? docs/SKILLFERRY_PLAN.md
?? docs/SKILLFERRY_RESEARCH_GPT_2026-08-19.md
 docs/README.md | 2 ++

Reuse was read-only: engine concepts and selected code segments were rewritten into skillferry's own tree (new history, no file parity); the source repository was not mutated in any direction.