Painter::draw_twice(child, first, |used| second) becomes Painter::measure
plus an ordinary draw. Iris's objection was the shape it forced on the
caller rather than the two draws themselves: the arithmetic that picks
the real region had to happen inside a closure, and anything it wanted to
keep came back out through a captured &mut. LazySpan::place was the only
caller, and it now reads as the three statements it is.
DrawMode::Measure is that draw with everything it writes switched off --
no arena slot, no mask, no move slot, nothing left in `active`, nothing
marked dirty. Only the returned Size survives, and the widget is left
exactly as it was, so the real draw that follows is an ordinary first
draw or redraw. That last part is load-bearing: a measurement that left
an ActiveData behind would let the following draw hit draw_inner's
"already at this region" fast path and return having drawn nothing.
A measurement also does not consume a redraw mark, since it is not the
redraw the mark asked for, and it takes none of the fast paths, since
"already drawn here" cannot report a size.
Every Painter method that writes now returns early on the mode -- a
widget's own draw never checks, which is the point. A debug_assert at the
end of draw_inner catches one that forgot, because the failure otherwise
is a single leaked primitive per measured widget per frame, which a
screen redrawn every frame turns into an arena that grows without bound.
What this is worth, and what it is not. The amplification it applies to,
measured on a streamed frame: 1,083 Widget::draw calls over 113 distinct
widgets, with the worst drawn 11 times at nesting depth 7-8 -- it is not
two draws but two to the power of how many measuring ancestors a widget
has. Only the writes go away; the walk and the region arithmetic still
happen 11 times, and removing those needs a size answerable without a
draw, which LAYOUT.md section 5 rules out. Streamed frame p50 1.39ms ->
1.22ms, p99 4.75ms -> 3.58ms. The upload numbers do not move, because
slot recycling had already made the discarded writes free in arena terms.
Also extracts move_slot_for from draw_inner, since measuring must not
allocate one and the reuse-in-place rule wanted saying once.
Verified: run-tests.sh, iris's suite, clippy and rustfmt clean, and the
headless phone render is byte-identical to the previous commit's on the
real GPU (Venus, RX 7900 XT -- checked, not llvmpipe).
Iris: "the documentation is also pretty crazy too. Can you go through it
and remove everything that's already done and decided? There's entire md
files iirc for projects already complete. And many with checkboxes already
ticked off that just fill up context."
docs/RUST.md 8503 -> 905 the framework bake-off (options,
recommendation, twelve closed
experiment boxes) and two superseded
"where things stand" sections, out;
what the experiments settled kept as
one line each
docs/IRIS_TODO.md 1383 -> 229 fifty closed items and six
phone-report sections whose defects
are all fixed
docs/LAYOUT.md 1116 -> 829 the pre-implementation framing: the
old trait, the checklist, the
migration list, the pass conditions
docs/TEXTURES.md 496 -> 240 the prior-art survey, the proposal
and its review, all implemented
docs/REVIEW-*.md 673 -> 0 two completed review passes; the two
findings left open on purpose (mask
hit-testing, the phone's font set)
moved into RUST.md
What survives a prune is what cannot be cheaply re-derived: measurements
(the APK-size table, the phone bench reports), dead ends, invariants and
their reasons, and the design of what exists now rather than the route to
it. AGENTS.md now says that, so the next session prunes as it goes rather
than appending; docs/IRIS_TODO.md's header says items are deleted when
they land rather than ticked.
Deleting the two review files left eighteen citations dangling in code
comments that state their reason inline and cited the file for provenance
only — those now read "(review, 2026-09-06)" and carry no dead pointer.
The emulator's measured GPU capabilities moved to the this-machine-android
skill, where machine facts belong. IRIS.md and DECISIONS.md are dated
records and were not rewritten; each gained one note that paths in older
entries predate the 2026-09-08 crate merge, pointing at the mapping.
Not touched, deliberately: docs/DECISIONS.md's entries (that file *is* the
queue of things for Iris to review, so deleting decided items would remove
what it exists for) and iris/readme.md and iris/TODO, which are hers.
Verified: ./run-tests.sh and `cd iris && cargo test` green, clippy and fmt
clean in every workspace, and every remaining docs/*.md cross-reference
resolves.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Iris: "the organization of the rust rewrite is a mess right now... there
shouldn't be anything related to the app inside of iris. Iris is supposed
to be the UI framework alone." And, on the crate count: "I'm confused why
the app only code needs more than one crate though."
Nine cargo workspaces become three, and the port's project code -- which
sat in five places, four of them inside the framework -- becomes one crate,
`ai-app`, in `app-rust/`:
client-core -> app-rust/src/client
iris/transcript-ui -> app-rust/src/ui
iris/transcript-fixture -> app-rust/src/ui/fixture.rs + tests/ + touch/
iris/desktop-app -> app-rust/src/desktop + src/bin_desktop.rs
iris/android-app -> app-rust/src/android + android-project/
android-shell -> app-rust/src/shell
iris/ keeps core, macro, the iris crate, tabs-ui and rig-input, and now
mentions no session, transcript, setup or server anywhere.
Only two of the old splits had a reason that survived reading. event-model
stays a crate at the repo root because server/ depends on it too, so a
crate is what makes the backend and the app agree by construction. The two
Android .so names looked like a hard constraint -- a package produces one
library artifact -- until P2 turned out to already plan merging those two
Android apps into one; both faces now come out of libai_app.so, picked
apart by features so `--no-default-features --features shell` keeps wgpu,
parley and iris out of the Compose app's APK. docs/RUST.md's "One app
crate" has the rest, including what each remaining feature is for.
DECISIONS.md and SUBAGENTS.md move into docs/ with everything else.
Verified: ./run-tests.sh and `cd iris && cargo test` green, clippy and fmt
clean in all five workspaces, `cargo ndk -t x86_64` links libai_app.so,
build-apk.sh produces an APK that installs and launches on this checkout's
emulator (Gl ... virgl, as expected), and the phone-sized headless
screenshot renders the transcript unchanged.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
iris
