method: ask what else was running; and an absence from one search path is not an absence

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

docs/re/METHOD.md

@@ -2549,3 +2549,27 @@ defects is worse than no audit**, because its false positives are indistinguisha
 from its true ones until each is opened by hand. Seven to open by hand is worse
 than the one a reader found by reading. Recorded as a negative so the next person
 does not build it again.
+
+## Ask what else was running — and do not establish an absence from one search path
+
+Two rules from one iteration, both paid for.
+
+**1. What else was running.** `sylpheed-port`'s third correction in three
+iterations came from a confound they had created themselves: a test suite running
+alongside the run they were timing, worth a **7-percentage-point swing** — larger
+than most effects either of us has reported, and enough to invent a
+resolution-dependent contrast that does not exist. This session has done the same
+thing, running `cargo` builds and disc sweeps while an emulator boot was in
+progress, at least twice. **"What else was running" belongs beside "what can this
+be skipped by" as a question asked of every timing**, and it cannot be asked
+retroactively of a figure whose run is gone.
+
+**2. An absence from one search path is not an absence.** Chasing their proposed
+hardware-clock instrument, I wrote *"no `/dev/snd`, no ALSA and no PulseAudio"*.
+The first two hold. The third was **false** — I had checked `/run/user/*/pulse` and
+nothing else, while `pactl info` reaches a live server at `/tmp/pulse-…`. The
+conclusion survived (the only sink is a software-timed `module-null-sink`, so there
+is still no hardware rate here) but it survived by luck: I had asserted the strong
+form from a single probe. ⚠️ **A negative needs its reach stated at the moment it
+is written** — "not at this path" is what I measured; "not present" is what I
+wrote.