bin/springs.mjs is the sampler behind motion.css: damping ratio and stiffness in,
the 49-point linear() and the settle time out. Run with --settle it reproduces
the six curves the file carried byte for byte, so only the window changed.
Each spring is now sampled over the duration M3 publishes for the web (spatial
350/500/650 ms, effects 150/200/300 ms) instead of stopping at its own settle
time, so the *-duration tokens read Google's numbers. Sampling stays in real
time — point i is the spring at duration × i / 48 — so the bounce lands at the
same millisecond as before; a longer duration just holds the tail flat at 1, and
a shorter one pins the last point, at most 0.3% of the travel in one frame. Each
token's comment records damping, stiffness, settle time and sampled duration.
M3's second motion scheme is here too: [data-motion="standard"] swaps the three
spatial springs (damping 0.9, 0.2% overshoot instead of 9%) and their durations;
the effects springs sample identically in both schemes, so they are shared. The
reduced-motion block names both selectors, so it still zeroes every duration.
Plan: docs/plans/material-3-alignment.md step 5, findings core C8, C9.
Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Qwx5USif3wFFmxtHg5U1g9
