irisandClaude Fable 5.1
e10582a2cd
docs/REVIEW-2026-09-07.md's T1, T2 and T3. Each was confirmed by breaking
its subject on purpose and watching the new assertion fire, and each of
those breaks is recorded beside the assertion.
**T1** (`phone_screen.rs`) bounded the fling's duration with
`FlingCalculator::new(PHONE_SCALE).duration(velocity)` -- the calculator
under test -- and only from above, so it could fail when a fling ran too
long and never when one stopped dead, which is the symptom Iris actually
reported. The companion `assert_ne!(before, after)` passes on one pixel of
travel. It now takes both bounds from `fling_spline_reference.py`, which
gains this case's own line (`density=2.55 v=15250.0: distance=11057.424px
duration=2.0716s`), and measures travel in pixels from a row's own
on-screen extent -- 10527px against the reference's 11057, the 5%
shortfall being the frames a tracked row leaves the screen on. Scaling
`tick_fling`'s elapsed by 1000 reports "stopped after 8ms"; scaling its
delta by 0.01 reports "travelled 111px".
**T2** (`top_edge.rs`) asserted the per-row box only on the return leg,
so a regression that drew rows in the wrong place while travelling
*backwards* was checked by the row count alone. The first leg still
cannot assert it (an unmeasured row has to be drawn to be measured), so
there is now a third leg -- back again, every height known. Widening
`intersects_viewport` downwards passes all 40 forward steps and fails at
"back 6", which is the leg that did not exist.
**T3** (`top_edge.rs`) asserted a mask exists and sits inside the list's
box, never that any row primitive references it, so a broken
`Mask::parent` chain -- what d507ae4 introduced -- left it green while a
code fence drew unclipped. It now walks every row primitive's chain and
requires the list's own mask slot on it (and rejects a chain that loops).
Forcing `Painter::set_mask`'s `parent` to `NONE` fails it with "clips to
[Id(1)], a chain that never reaches the list's own mask Id(0)".
Verified: `cargo test -p transcript-fixture` (12) and `cargo test --lib -p
iris` (103) pass, fmt and clippy clean.
Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>