method: commit the tool before running it, and never edit it mid-run

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Wuu56cE8vJGTBtn1ppsk8v

docs/re/METHOD.md

@@ -2749,3 +2749,30 @@ of the other traps on this page.
 📌 Use a heredoc (`git commit -F -`) or single quotes for any message containing
 backticks. This page is full of identifiers in backticks, so the exposure is
 constant.
+
+## Commit the tool before you run it — and never edit it while it runs
+
+The third submenu sweep died because I **edited the sweep script while its own run
+was in flight**, and deliberately broke its decision rule with `sed` to check the
+new self-test could fail. The sweep reads its script when *it* starts — after the
+reach probe finishes — and that fell inside the window. It read the broken rule.
+
+✅ **The self-test caught it and refused to run**, on the day it was written,
+against a fault I had introduced. Without it the sweep would have reported
+`RESETS` for all three screens: confident, uniform, and fabricated.
+
+⚠️ Three further self-inflicted faults in the same hour, recorded because the
+failure was process rather than analysis:
+
+* a **competing `x11grab` during a measurement** — the concurrency confound
+  `sylpheed-port` had just warned cost them a 7-point swing;
+* `pkill -f x11grab` to clear it, which can kill the running probe's own capture —
+  this page already records `pkill -f` matching the caller's shell, biting the same
+  way from a different direction;
+* the **restore of the broken file sat as the last line of a command that timed
+  out**, so it never ran; recovering with `git checkout` then discarded the entire
+  uncommitted rework.
+
+📌 **An uncommitted tool is one timed-out command away from being unrecoverable,
+and a tool edited during its own run is not the tool that ran.** Commit first, then
+run. Cheap, and it would have prevented all four.