# The top-level clock freezes at the settle point — and that closes the 114-vs-120 gap

**Classification: measured.** From the title draw capture of 2026-08-29
(`ui_draw_capture.sh ARM=early`), re-read with the per-quad parser.

## The observation

`GP_TITLE` build 4 declares a timeline of `t = 0 … 269`. At this run's build-in
pacing that is about 120 presented frames. **The title dwell lasted ~1 100.**

| element | declared alpha ≥ 1 | drawn in frames | span |
|---|---|---|---|
| `ptcopyright` | t = 138 … 244 (**106 units**) | 168 … 1217 | **1 050 frames** |
| `ptlogo1` | t = 26.6 … 264 (237 units) | 125 … 1220 | 1 095 frames |

If the top-level clock ran on to the end of its declared timeline, `ptcopyright`
would fade out at t=244 — around frame 216 — and `ptlogo1` at t=264. **Neither
does.** Both are drawn continuously until the dwell ends, and disappear within
three frames of it.

> **The top-level clock advances through the build-in, stops at the settle point,
> and holds there. The exit ramp is not played on a timer — it plays when
> something makes the screen leave.**

That is [`ui-settle-time.md`](ui-settle-time.md)'s decode seen from the other
side, and observed in the running game rather than inferred from the file. The
freeze lands inside the settle window `[160, 236]`: `ptcopyright` reaches full
alpha at its start (t=160) and never moves again.

Meanwhile the plate's focus record keeps looping throughout — a nested record runs
on **its own clock**, which does not stop when the parent's does.

## 🔴 What this closes: the 114-unit period, which was my error

[`ui-record-loop-length.md`](ui-record-loop-length.md) recorded an unexplained gap:
the plate glow's period of **51.158 presented frames**, multiplied by **2.231**
units/frame, gives **114** units against a declared **120**.

**The two numbers come from different clocks.** The 2.231 was regressed over five
*build-in* events — the only stretch in which the top-level clock advances. The
51.158 was measured over the settled dwell, where that clock is frozen and only
the record's own clock is running. Applying one to the other compares two
different stretches of wall time, and there was never a reason they should agree.

The 120 was never in doubt from evidence that needs no conversion: the
**dark-fraction test** (17.7 % measured, 14.4 % predicted by 120, 2.2 % by 105,
with a culling threshold of 1 read off the data) refutes 105 by a factor of eight
without any units/frame at all. **The gap was an artefact of my arithmetic, not a
discrepancy in the decode**, and the doc no longer carries it as open.

## ✅ The period itself, confirmed twice

51.158 frames was originally measured by detecting cycle starts. A second,
independent estimator — autocorrelation of the glow's alpha series — returns
**lag 51**, with clean harmonics at **102** and **154**.

⚠️ **And the first version of that estimator failed its control**, which is why it
is worth recording. Indexed by *sample position* it returned **48** for a period
known to be 51.158 — 6 % low, with the top three lags (47, 48, 49) not even
bracketing the truth. The log's frame numbers have gaps, so a lag of *n samples*
is not *n frames*. Indexed by frame number with missing frames masked, the control
passes.

## ❔ What this does not settle: the sweeps' period

The same validated estimator, applied to the two light sweeps, gives periods that
**disagree between two dwells of the same screen**:

| sweep | dwell 1 | dwell 2 |
|---|---|---|
| tall quad, h ≈ 1134 | **515** frames | **452** frames |
| tall quad, h ≈ 1303 | 549 frames | 538 frames |

A 14 % disagreement within one screen is not a period. The likely reason is that
the quad's x is a composite of the parent's placement with the leaf's rotation and
600–800 % scale, so "the quad's left edge" is not a clean phase variable — but
that is a hypothesis, not a finding. **The sweeps' period is unmeasured**, and the
`+0x08` field cannot settle it either: `ptloop01`/`ptloop02` have zero slack, and a
zero-slack record cannot distinguish "loops at 600" from "runs once and stops".

## 🔴 Blocker: a single Ⓐ on the title faults the guest

Three attempts to capture the **main menu** ended the same way.

| run | input | outcome |
|---|---|---|
| 1 | Ⓐ on title, then Ⓐ again on the transition | guest fault, **519 MB** of register dump |
| 2 | one Ⓐ on title (guard added) | drifted to a `flight` classification, 97 MB |
| 3 | one Ⓐ on title | guest fault, **223 MB** of register dump |

Against three runs in the same session that tapped nothing on the title and all
completed normally. This is the crash `ui_draw_capture.sh`'s own header records
from 2026-08-18 — "a stray A there sends the guest into the save-data probe".

⚠️ **It bounds menu-side dynamic RE in this container**, and it is not a
contradiction of the corpus's existing menu measurements, which were taken before
and by some route that survived. What differs has not been found.

⚠️ **And a guest fault writes an unbounded register dump to stdout** — 223 MB and
519 MB here, on a filesystem at 91 %. Any scripted run that presses a button needs
a size guard on `canary.stdout`.

## Reproducing

```bash
python3 tools/re-capture/quads_per_frame.py <log> 200 1200
```