v3.9 homepage: figure legibility and video quilt

This is the local verification record for the 2026-11-03 homepage changes. No commit or deployment has been made for this round.

Scope and source

The desktop hero places Collections beside the introduction and stacks it below
the introduction at narrow widths. The opening no longer waits for hero video.
Projects & Ideas retains the PowerPoint-derived BipedalWBC figure and adds an
“In motion” quilt beneath it; the figure SVG itself was not rebuilt or edited.

Edwin selected z_workspace and orientation for the two simulations, lower
for the z-height lab video, and the original board-wiping recording. All labels
use neutral descriptions, and the segments retain original speed. Private
originals, contact sheets, Drive identifiers, crop and segment details are
recorded in the nonpublished experiments/home-redesign/media-source.md.

The four encoded 640×800 MP4s total 783,518 bytes. Their sizes and SHA-256
hashes were checked against that provenance record:

Clip	Bytes	SHA-256
z_workspace	205,981	08478f0d5c52dba6f6d381139374aed1c805d0301e75c936a1c9dcaf90c3dfb7
orientation	143,166	fae91c7fd3defb36fb37f6ce75b9f14621bdc8aa58a803762692ad78729dcdd0
lower	199,810	47d2279735074396e608d858edf095cbae4abb30c1c7bade24afdb59b19da645
board	234,561	980eedaaaa205543139f519a2bc0c0af63bfc05ebb825027598a5fff179ea633

Checks completed before quilt integration

The following results apply to the earlier partial implementation, not yet to
the final quilt integration:

Check	Result
MkDocs strict build	Passed
Python unittest discovery	22 site tests passed with 3 skipped; 138 tools tests passed
Figure gate, Chromium, 900px viewport height	857px width static, 858px animated
Figure gate, Chromium, 1440px viewport width	614px height static, 615px animated
Resize during figure pin	Shrinking to 800×900 preserved the measured figure top (0px change), removed the pin spacer, and opened the step descriptions
Start Here calibration preview	Four nodes and three edges rendered without a page error
Hero	1440, 1024, 1023 and 390px checked with no horizontal overflow; introductory copy occupied two lines at 1440px

The project hook emits the smallest source text/math-strip measurement. The
configured threshold is extra.figure.minLabelPx: 9; the current smallest
source label is 10pt. The gate is measured against the predicted animated
canvas, not a fixed viewport-width media query. The 700px breakpoint still
controls the additional static step crops.

Final integration checks

• MkDocs strict build passed after integration. Python unittest discovery ran 23
  site tests (3 skipped) and 138 tool tests successfully. The figure-gate
  browser regression and the opening's deck, icon and typing checks passed.
• Edge headless at 375, 820 and 1440px in both palettes showed one, two and four
  columns respectively, no horizontal overflow and aligned quilt/figure edges.
• The four sources played; raster, mix and real states and reversal were checked
  visually. Save-Data requested no MP4; no-JavaScript and no-WebGL fallbacks
  displayed posters. Reduced motion loaded no video until explicit playback.
• Pausing persisted across five Home/Friends navigation cycles. Five old WebGL
  contexts were released and one remained for the current homepage. Offscreen
  clips paused and sufficiently distant sources detached.
• At 4× CPU throttling, an Edge DevTools trace measured 607 animation callbacks:
  0.78ms mean, 4.03ms P95, 8.59ms maximum. These include other page and test
  callbacks and are not complete per-frame measurements; the 4ms target cannot
  be claimed as met.
• The older tests/test_figure_anchor_once.cjs timed out waiting for two
  removed .research-figure diagrams. It predates their replacement by the
  BipedalWBC figure and is not a passing integration check. The current figure
  gate and resize regression passed separately.

Safari, a real touch device, the full requested viewport matrix, initial-load
transfer/CLS, pin geometry before and after loading, standalone rAF counts and
five cycles including an ENotes article were not verified. Source-code
reverse-engineering tooling was unavailable; the quilt implements the provided
reference description rather than claiming an independent bundle audit.