diff --git a/docs/re/canary-scripted-input-traps.md b/docs/re/canary-scripted-input-traps.md
index 1b773e5..e3a9d39 100644
--- a/docs/re/canary-scripted-input-traps.md
+++ b/docs/re/canary-scripted-input-traps.md
@@ -299,3 +299,19 @@ changes. Whatever ignores Ⓐ at an attract title is a *consumer* further up, an
 finding it means identifying the object the poller fills (passed in as `r3` from
 the per-frame update) and then its readers. That is a real RE job, not a
 one-iteration probe, and it is where this thread now stands.
+
+### A confound in all of the above: the box was not always idle
+
+Worth recording against every timing number in this entry. The container runs
+the emulator, the Canary build, and Reborn's disc test suite on the same 12
+cores, and Xenia alone uses about **5.5**. Several of the Ⓐ experiments — and
+most of the boot-duration measurements — were taken while a `cargo test` or a
+`build-canary` was running. One boot then failed to reach the title at all
+within 400 s, where an unloaded boot reaches it in 130–290 s.
+
+That does not explain the Ⓐ result on its own: the interleaved A/B alternated
+arms under whatever load was present, and the latest title of all (268 s)
+*accepted* while a 232 s title refused. But a starved guest missing an input
+window is a live hypothesis that the data collected so far cannot exclude, and
+the honest next measurement is the one now being taken — the same navigation on
+an **idle** box, with nothing else running.