Development record

2026-08-30 — The in-place mutation hazard graduates from a session habit to the committed record as itd-193, a discipline: a verifier works on a copy, and whoever acts on a tree proves it clean immediately before the act rather than inheriting an earlier check. Occasioned by a reviewer running its mutation matrix against a live build worktree while a peer review, correctly, reported the modification as untouchable peer work it could not distinguish from real work. Routed by the four-piece table: the stance and its gate to a discipline record; the operational line to the AGENTS.md concurrent-sessions section beside the peer-work rule it complements; no capability, because the documented protocol is the MVP at this rung (script-first-mvp); no ADR, because it governs method rather than architecture. Adjacent to the one-writer-per-file principle and deliberately not folded into it: that principle governs committed records across merge windows and puts per-worktree files out of scope, while this governs the working tree inside a single window. REACH IS THIS REPOSITORY ONLY and the record says so — a rule reaches every abcd-managed repo through a bundled default domain compiled into the binary, which is a code change and its own intent; rung 2 (a recall-injected domain rule) and rung 3 (a mechanical clean-tree assertion) are named in the record and neither is claimed.