# The plate-pulse gate phase-locks the shutter to the title animation

**measured** — 2026-08-30 · [data](../data/title-sweep-jp-draw-capture.txt) ·
instrument `tools/re-capture/jp_draw_capture.sh`, control the English title
draw log

## The claim

`wait_plate_pulse.py` waits for the title plate's glyph count to sit in
[500, 2500] for 12 samples, and every title capture in this corpus shutters on
it. It was adopted to answer *"has the screen settled?"* — and it does.

But the plate's pulse **is** part of the title's animation, so gating on it does
not only wait for settling: it **synchronises the shutter to the animation's
phase**. Two runs gated this way are not two samples of a free-running clock.

## The measurement

The x of each tall ROT strip at the **first captured frame** — the shutter
instant — in two independent runs, different sessions, *different locales*:

| strip | EN run | JP run | apart |
|---|---|---|---|
| 883×1134 | x = −109 | x = −83 | **26 px** |
| 1299×1303 | x = 486 | x = 461 | **25 px** |

Against a traverse of ~1600 px, that is **1.6 %**. Two boots, two locales, two
sessions, and the sweep is in essentially the same place both times.

## What it invalidates — my own reading

[`jp-title-at-rest.txt`](../data/jp-title-at-rest.txt) reasons that its second
capture probes a new axis, *"BETWEEN runs, where a free-running clock lands
somewhere else on a fresh boot"*, and reports **RMSE 0.32** in the era box as
the between-session **capture noise**.

🔴 **The clock does not land somewhere else.** The gate puts it back in the same
place. So:

* **0.32 is a phase-locked LOWER BOUND on capture noise, not capture noise.**
  At an arbitrary phase the in-box figure is the **11.9** measured between two
  EN captures a plateau-phase apart. Anything reusing 0.32 as "the noise floor"
  is quoting the gate, not the game.
* I read the 0.32 as evidence the JP title is **still**. It is not. It is
  evidence the **gate works**. I had it backwards.
* The whole-frame 116 492 px that *do* differ between those two sessions are
  consistent with exactly this: ~25 px of residual jitter displacing two large
  bright diagonal strips moves a lot of pixels globally while barely clipping
  the era box.

## What it does NOT invalidate

✅ **The era adjudication stands.** Its margin is **16.72** (41.69 fixed vs
58.41 stale), which exceeds even the un-locked **11.9** figure — so it survives
whichever noise number is correct. And the file's own key insight is untouched
and is the reason it survives: capture noise moves both candidates together and
**nearly cancels in a margin** (absolute scores moved 0.001–0.002 between
sessions; the margin moved 0.001).

✅ **The within-run at-rest result stands** — five frames ~1.5 s apart are *not*
gated individually, so they sample different phases, and the logo ROI is
byte-identical across them in **both** sessions while 5–8 % of the frame moves.

## Reach of the negative

This says the gate locks phase; it does not say by what mechanism. Both runs
boot the same ISO from the same state, so the pulse may simply occur at a fixed
offset from a deterministic boot rather than the gate doing the locking. **Two
runs deliberately shuttered at different phases would separate those** and were
not run.