re: build the fast probe -- and it refutes the diagnosis that motivated it

Last iteration I blamed four failed runs on the probe sampling every
~41 s, slower than the title screen lasts, and withdrew three earlier
conclusions on that basis. Building the fix tested the claim and killed
it.

The speedup is real and control-verified. One long-lived ffmpeg x11grab
stream, raw RGB, glyph counted in numpy -- no per-sample process startup,
no PNG encode, no convert -crop:

  wrapper `screenshot`            3.98 s per sample (emulator running)
  import -window root -> PPM      1.20 s
  long-lived x11grab stream       0.29 s          13.7x

The counter is byte-identical to is_title.py: 753 on the committed title
capture, 327 on the main menu.

Pointed at a running game it says the opposite of what I expected:

  332 frames in  85.3 s = 3.89 fps; max glyph 0
  1674 frames in 420.0 s = 3.99 fps; max glyph 0

1674 consecutive samples over seven unbroken minutes, four per second,
zero green-(A) pixels. Sampling rate was a real defect that happened not
to be the cause.

So "neither locale reaches the interactive title without a pad press" --
withdrawn last iteration for want of evidence -- is reinstated, now as a
dense measurement, with its reach stated: a MID-RUN window only, silent
about the boot title.

Leading hypothesis, unconfirmed: the PRESS (A) plate appears only in the
boot title window and the attract loop's title carries none, which is
exactly what title_states_capture.sh was written to test. The experiment
is to start the fast probe from t=0 rather than attach to a run already
in progress.

METHOD: fixing the instrument is how you test the explanation that blamed
it -- a plausible mechanism is a hypothesis, and the fix is its
experiment, not its proof.

docs/re/METHOD.md

@@ -510,3 +510,11 @@ agent's loop prompt, i.e. nowhere durable. See [`README.md`](README.md) for the
   classifies movie-vs-static on an *absolute* rmse threshold — so the gamma
   change biased the very classifier the run depended on. Harness thresholds tuned
   on one output configuration are not portable to another.
+* **Fixing the instrument is how you test the explanation that blamed it.** I
+  diagnosed four failed runs as "the probe samples slower than the event",
+  wrote it up, and withdrew three earlier conclusions on that basis. Building the
+  faster probe refuted it: at 100× the sampling density, over 420 unbroken
+  seconds, the event still never occurred. The diagnosis was a real defect that
+  happened not to be the cause — the most seductive kind, because fixing it feels
+  like confirmation. A plausible mechanism that explains a failure is a
+  hypothesis, and the fix is its experiment, not its proof.