A container that probes a child's size was still doing it with a real
draw, so `Painter::measure` existed and almost nothing used it. Tracing
every draw of one streamed frame: 1,083 `Widget::draw` calls over 113
distinct widgets, the worst drawn 11 times at nesting depth 7-8, every
one of them mode `Draw` and none of them dirty. The cache was working --
each of the 11 was offered a genuinely different region, alternating
between an oversized probe box and a real one.
ScrollArea::draw was one of the two sources. It drew its whole content
at a box built from a stale hint, read the length back, corrected the
scroll position, and drew the content again where it belonged. The first
of those is now a measurement.
The other half is the measure fast path. A widget's reported size is a
function of its own state and the size it was offered, not of where it
was offered -- so an undirtied widget already drawn at a region of this
size has already answered, and `active.size` is the answer. This is the
same assumption `mov` makes one branch further down (same offered size,
therefore identical output, therefore a translation); it is only stated
as a size here rather than acted on as a move. Without it a measurement
costs a full recursive walk, which is what made the nesting compound.
A measurement now also peeks at the redraw mark instead of consuming it
-- it is not the redraw the mark asked for, and swallowing it would
leave the widget stale until something marked it again.
453 draws from 1,083, and the streamed frame is p50 1.18ms (from 1.22ms,
and 2.20ms before this run of work). The headless phone render is
byte-identical to the previous commit's on the real GPU.
What is deliberately NOT here: the same change to `Span::draw`'s phase 1,
which is the remaining 2x and which moves the layout by a few pixels.
The layout stays intact -- it is a position difference, not a broken
frame -- but which of the two is correct was not established, and the
suspicion (that phase 2 now takes `mov`, and `mov` accumulates deltas
where a redraw recomputes) points at a bug in `mov` rather than in
`Span`. Written up in docs/IRIS_TODO.md with Iris's target shape for
`Span`: no probe phase at all for `abs` children, and a `rest` child
forcing a reposition pass rather than a redraw.
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).
arena_churn says a streamed frame uploads 72.7% of the instance arena
and that this is the floor, against 3.3% for a fling over the same
content -- so the rows are being redrawn where a scroll would write one
move_offsets delta. The upload half landed in 3c7d3db; this is the
layout half, with the measurement, the control that makes it convincing,
and where to look first.
Changing any primitive re-uploaded every primitive. Measured over the
bench fixture by the new arena_churn rig: 758 MB across a fling and
1.2 GB across 401 streamed deltas, p50 3.0 MB per streamed frame.
Three separate things were wrong, and only the first is what it looked
like from the outside.
ArrBuf reallocated on every length change. A fresh Buffer's contents are
undefined, so adding one glyph -- which a streamed reply does constantly
-- forced a full rewrite, and no partial upload could have been correct
in the first place. It has a capacity now, growing geometrically and
never shrinking, and update() answers whether the Buffer identity moved
so a caller can rebuild its bind group and force the whole range dirty.
That alone took the glyph array from 95% re-uploaded to 3%, and stopped
primitive_group being rebuilt on every frame the arena changed.
A redraw freed its primitives and pushed new ones. Freed slots are not
reusable until the end of the frame -- a layer's draw order still names
them -- and Painter::draw_twice is how a container learns a child's
size, so with containers nested the arena's high-water was the transient
push count rather than the live one: 17 million pushes across 401
deltas, 127,443 slots for 11,569 live primitives, growing linearly with
the transcript. A redraw now gets its old handles back as a recycle pool
(Painter::take_recycled, Primitives::recycle) and writes into the slots
it already holds; the pool is consumed in order and whatever the draw
does not claim is freed when it ends. The arena is exactly the live
count now. The CPU frame improved with it, from p50 2.20ms to 1.39ms on
the stream run, because the freeing and the draw-order renumbering went
away.
Nothing tracked which entries changed. util::Dirty is a bitset per
uploaded array, coalesced into ranges at a 1 KiB gap. Marking is O(1)
and allocation-free; reading it back is one word per 64 entries. Both
alternatives were measured and rejected: a min..max span is nearly the
whole buffer, since a frame's changes land in 5-20 scattered runs, and a
Vec of indices would mean an allocation and a sort per frame at several
thousand marks. It replaces Primitives::updated -- one bool that covered
the instances and the per-primitive data together, so rewriting a rect's
region re-uploaded every glyph -- and TrackedArena::changed.
The trap only the rig could catch: writing an entry is not changing it.
Recycling rewrote every glyph of every moved row with identical bytes,
marking 73% of the glyph array against 0.6% genuinely changed, because
what moves is the instance's region and not the glyph. PrimitiveVec::set
and Primitives::set_instance compare before marking.
Every array now uploads within a hair of its floor: fling instances 3.4%
against 3.3%, fling glyphs 0.9% against 0.8%, stream glyphs 0.6% against
0.6%. Stream instances are at 72.7%, which *is* the floor and is a
layout question rather than an upload one -- the list is pinned to the
newest end, so a growing reply moves every row, and that should be one
move_offsets write rather than a redraw. Noted in RUST.md as the next
thing.
Also: draw_inner's four old_* parameters become one Retained struct, so
the recycle pool is a field rather than an eleventh positional argument
next to three others of the same shape; and free_primitive is the one
place a slot and its draw-order position are retired together.
The rigs move to scripts/rigs/ui-profile, a crate of their own so a
rig's dependencies stay out of the app's -- arena_churn needs bytemuck,
which nothing in ai-app does. arena_churn prints floor, uploaded and
whole side by side per array, because any two of those alone are
misleading and the 122x over-marking above was invisible until all three
were on screen together.
Iris, on the two findings from the incremental-text investigation:
"let's switch to new lines for the test, and also let's keep the single
line around for stress + could be something to try to optimize later."
The streamed tail now takes a blank line every 4-12 deltas, so it is 53
markdown blocks with a longest of 502 characters instead of one block of
14,888 -- against a measured p50 of 147 and a largest-ever 1,580 over
7,706 blocks of real assistant messages. Layer 1's streaming frame went
from p50 3.86ms / p90 8.65ms / worst 10.95ms to p50 2.20 / p90 5.90 /
worst 8.78.
The run-on message is kept as the first two backlog events, 14,824
characters in one block, just under text_cap's 16 KiB so it draws in
full. The *streaming* pathology stays in frame_profile.rs rather than the
fixture: it needs a growing block, and iterating on it there costs a
second instead of a two-minute phone run.
Adding it is purely additive -- the random state is saved and restored
around those two events, so every other backlog event is byte-identical.
That is not tidiness: the first attempt shifted the backlog and broke
`a_long_press_and_drag_selects_text`, which replays a real recording at
(300, 1000) and needs the content it was recorded against to still be
there. BACKLOG_COUNT is 3202 now, in generate.py, fixture.rs and
BenchFixture.kt, which split the file by line index.
And the answer to Iris's question, which the code already had: the newest
message does *not* cap. `build_row`'s `cap` is false for the live tail
because a row that grew while capped would appear to stop growing, and a
reply growing past the cap is never caught either since it grows through
apply_delta. So a streamed block's shaping cost has no ceiling -- ~29ms
per delta at 50k characters, ~58ms at 100k.
Recorded but not chased: the emulator's `stream: build p50` did not move
(10.4 -> 10.5ms) while layer 1's frame nearly halved, so most of a
streaming frame on a GPU path is the whole-arena primitive re-upload
layer 1 never performs -- 11,568 primitives rewritten per delta, with the
fling phase as the control at 0.4ms for the same primitives moved
through move_offsets.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Iris asked to look into incremental text rendering, hoping parley
supported it. It does not, by design: a `Layout` re-linebreaks and
re-aligns freely but "if the text content or the styles applied to that
content change then a new `Layout` must be created", its LRU cache holds
harfrust's per-font shaper data rather than shaped runs, and its own
`PlainEditor` rebuilds the whole layout from the whole buffer on every
keystroke.
The app already does what incremental layout would buy: `RowBlocks::
apply_delta` keeps one `TextEdit` per markdown block and re-shapes only
the one a delta landed in. Re-splitting the markdown to find it is 18µs
at 18,000 characters; comparing the blocks is 470ns.
What is left is one `TextBuffer::shape` of that block, linear in its
length at ~0.23ms per 1,000 characters here -- and the bench fixture's
streamed message is 14,888 characters in a *single* block, a run-on
paragraph with no blank line in it, so every delta reshapes all of it.
That is 3.5ms of the measured 3.86ms frame.
Real replies are not that: across 7,706 top-level blocks from 3,675 real
assistant messages on this machine (lengths only, no content copied
anywhere), p50 147 characters, p90 449, p99 836, largest 1,580, nothing
above 4,000; code fences p50 126, largest 589. At those sizes a reshape
is 48µs to 372µs here, roughly 0.12-0.93ms on the phone -- inside a
120Hz budget with no incremental anything.
So the recommendation is not to build it, and to give the fixture's
streamed message the paragraph structure a real reply has instead. Three
runs added to `frame_profile.rs` so none of this is re-derived: what
reshaping a growing message costs (including at the sizes real replies
reach), where a delta's cost is, and what the fixture actually streams.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Iris's phone came back "now THAT is smooth", and reading that run against
the bench's own timings found three things the report was getting wrong
-- two of them shipped yesterday in the fix for the last three.
`missed vsyncs` counted idleness. Every gap between frames was treated as
cadence, so the bench's own pauses read as stutter: 276 for sixteen 300ms
rests between flings, 2410 for twelve hundred 50ms keystroke gaps, 821
for four hundred 50ms stream gaps -- each within a few percent of the
arithmetic. A gap now measures anything only if the frame before it had
asked for another one.
`late` counted the swapchain wait as cost. A well-paced loop spends each
frame blocked in the acquire, so its total sits at exactly one refresh
period and every frame lands on the budget boundary -- 0.4ms of work and
5.7ms of waiting is not a late frame. It is judged on `FrameParts::work`.
And the refresh rate is the larger of what the platform claims and what
the run sustained, because each can only be wrong one way.
`Display.getRefreshRate()` answered 60 for a run that drew 3405 frames in
33.1s, since a phone that varies its rate answers with whatever mode it
is in when asked. The first attempt at measuring it instead took the
fastest tenth of the gaps and reported 88Hz for this repo's 60Hz
emulator, whose app manages 54 -- a budget no frame there could meet,
invented out of the app's best moments, and caught only by running the
corrected report on the emulator before shipping it. A sustained rate is
a floor and cannot do that. Both are printed when they disagree.
Also corrected in the docs: "103fps on a 120Hz screen" divided the fling
phase by its whole duration, rests included. Both runs sustained ~120.3fps
through the motion, so the callback ordering was never costing frames --
what changed is the clock, which moves no frame count at all, which is
exactly why nothing in a report could show it.
`fling_profile.rs` is `frame_profile.rs` and gained a stream run, which
says where the frame time now is: folding an arriving event is 0.35ms and
applying the diff 0.41ms, while the frame is 3.86ms here and 9.5ms on the
phone. 401 events move the item count 652 -> 654, so nearly every one is
a delta into the same row -- the cost is re-shaping one growing message,
not `fold_event`'s per-event clone, which was the hypothesis and is what
measuring it ruled out.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Iris, from her phone: "some stuttering when flinging in particular.
Harder to notice with my finger directly moving the scroll." Her fling
phase was 103fps on a 120Hz screen at p50 6.3ms.
Two of the four things found are corrections to the instrument, not the
renderer. The swapchain acquire -- `get_current_texture`, which *blocks*
until the compositor frees an image -- was inside the span the report
called iris's CPU work, so a fling comfortably ahead of the display read
as milliseconds of being slow. A frame is now three measured parts
(`FrameParts`: build, acquire, submit), per phase as well as per run. And
nothing could say a frame was never *produced*: `late` counts frames that
cost too much, which a reader does not see, while a frame that never
happens leaves the last one up for two refreshes, which is the stutter.
`PhaseStats::missed` counts vsyncs nothing was drawn for. It closes on
the emulator: 1548 frames + 452 missed over 33.0s at 60Hz is 1980
vsyncs.
The other two are the frame loop. `Choreographer.postFrameCallback`
schedules for the next vsync after the call, and iris asked at the *end*
of the callback -- so any frame whose work ran past the boundary
registered too late and got the vsync after, one frame over budget
silently costing a second. It is asked for immediately after
`tick_animations` now, on both backends. And the fling was advanced on
`Instant::now()` rather than the vsync `do_frame` carries: frames are
presented on an even cadence whatever clock computes them, so sampling
the spline at "whenever the callback ran" moves the content unevenly with
no frame late enough to appear in any report -- and a drag never had it,
which is the asymmetry Iris described. `PointerClock` is `DeviceClock`
and the view keeps one, anchored by whichever of a touch or a frame comes
first, so a fling is advanced on the clock its velocity was measured on.
`opt-level` for the Android release build goes from "s" to 3. The table
in RUST.md picked "s" on bytes alone; over the same warm fling eight
times iris's own per-frame work is p90 0.15ms/p99 0.42ms at "s" against
p90 0.09ms/p99 0.26ms at 3, for 1.8 MB of arm64 APK.
`app-rust/tests/fling_profile.rs` is the rig that established what a
fling frame actually costs and is kept for next time (Iris: "please keep
the profiling rig around for future use"): only one frame in six lays
anything out, and the multi-millisecond spikes are all first-pass.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Iris: "remove both decisions and iris.md. I've decided to instead make
decisions when planning with agents rather than after they do things, and
they're both too long for me to wanna read, + don't cover all the
decisions I'll wanna make about the code anyways. I'll just naturally run
into things for now. Todo is important though."
So docs/DECISIONS.md (850 lines) and docs/IRIS.md (1,986) are gone, and
AGENTS.md now says not to start another: raise a choice while planning it
with her, otherwise decide it and put the reasoning at the code it
governs. The TODO lists stay. docs/SUBAGENTS_DECISIONS.md went with them
-- same artefact, same reasoning, and she did not name it, so its six
decisions were folded into docs/SUBAGENTS.md rather than deleted.
Deleting the logs left ~30 citations dangling in code comments and docs.
Each states its reason inline and cited the file only for provenance, so
they now read "decided 2026-09-07" or name the module doc that carries
the reasoning.
The root had six things that were not a program or a document. Moved,
per "I only meant top level sh files":
run-tests.sh, test-wg-tunnel.sh, wg-setup-host.sh -> scripts/
rigs/ -> scripts/rigs/
xtask/ -> scripts/xtask/
A project's own scripts stayed with the project: app/*.sh, app-rust/*.sh,
iris/*.sh and server/enroll-link.sh did not move.
`target/` at the root is deleted and cannot come back: there was never a
workspace there, and the 29 MB was only xtask's scratch space, now in
scripts/xtask/target/. `cargo xtask apk` still runs from the repo root
and now publishes to scripts/build/outputs/apk/<mode>/ -- one directory
deep, because that is what Dev Updater's `*/build/outputs/apk/*/*.apk`
discovery pattern needs, and scripts/xtask/build would have been two.
Verified: ./scripts/run-tests.sh and `cd iris && cargo test` green, clippy
and fmt clean everywhere, `cargo xtask apk debug --abi x86_64` builds and
signs an APK carrying lib/x86_64/libai_app.so at the new publish path, and
the repo root is now eleven entries with no build output among them.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
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, correcting the previous commit: "Why does the mask matter at all.
If you want a mask then you add .masked(). It should just prevent rows
that aren't in its region at all from drawing ... Just like the opt in
scrollable, masking should be opt in."
So `LazySpan` sets no mask. It culls -- a row entirely outside the box it
was offered is never drawn, which `intersects_viewport` already did -- and
draws a straddling row in full, because virtualisation decides which rows
and never how much of one. Cutting off that overhang is `.masked()`, added
by whoever wants it.
The transcript wants it (it is a list under a header bar) and opts back
in; the benchmark does not and needs no ceremony. `top_edge.rs` goes back
to reading the mask the list *inherited*, which is now also the test that
the transcript is still asking for one.
The previous commit had the span mask itself, which fixes the panic and is
still the widget deciding what is not its to decide.
Four things Iris asked for on 2026-09-08.
**A LazySpan no longer cares about masks.** It asserted that something
around it had called `.masked()` and refused to draw otherwise, which is
why a plain full-screen list -- the benchmark, any simple app -- panicked.
It cared only because it draws a row straddling an edge in full and relied
on somebody else to cut off the overhang; it clips itself to the box it
was offered now. Strictly stronger than the assert, which a mask *larger*
than the list's box satisfied while letting the overhang through anyway --
the fault it was written for. The transcript's `.masked()` wrapper goes
with it, and `Painter::is_masked` with that.
**Everything on the transcript screen is capped.** One rule in one place,
`client_core::text_cap`, mirrored as `TextCap.kt` with the same numbers so
a bench comparing the apps compares renderers rather than policies:
a tool call's input 80 lines or 4 KiB -> "Show all N lines"
a tool call's output 80 lines or 4 KiB -> (already was, in iris)
a message 200 lines or 16 KiB -> "Show all N lines"
The input is what the edit-card report needed: an Edit's old_string and
new_string arrive whole and are routinely the biggest text on screen.
Messages are capped in both apps, user and agent alike.
Three rules that took a screenshot to get right. A message is cut on a
block boundary, never mid-block -- cut to its own opening line a fence
renders as an empty panel, which reads as a fault rather than as a cap --
except a message that is one enormous block, which is truncated, since
dropping it would leave the row blank. A reply still streaming is never
capped. And the input's two blocks share one "Show all", while input and
output have their own.
**Compose stops wrapping raw text**, per Iris's call: a tool's leftover
input fields and its output pan sideways like the command already did.
`on_tap` and hold-the-edge move to `transcript-ui/src/tap.rs`, since a
message's "Show all" needs exactly what a tool card's tap already had.
Iris's report was that expanding a tool card holding a long,
horizontally-scrolling edit lags on her phone. The cause is not text
layout: shaping and rasterising a 51,200-glyph block is 20ms, and the
frame that drew it took 1.37 seconds.
A widget redrawn in place frees every primitive it owned and writes
fresh ones. Freeing compacts each layer's draw order with swap_remove,
so ~N primitives are renumbered, and finding the handle to renumber was
a linear scan of everything that widget drew -- O(N^2) in the widget's
own primitive count. A paragraph never notices; one text widget holding
a whole old_string and new_string is every glyph in the card.
The arena now records, per slot, where that slot's handle sits in its
owner's ActiveData::primitives, written at the one place a handle is
taken (Painter::own), and apply_free indexes straight to it.
50,000 glyphs, redrawn: before 636ms after 2.4ms
per glyph: before 12.7us after 0.043us, flat in N
benches/message_list.rs gains scenario (g) for it, reporting per-glyph
because flat is the pass condition and a total hides it. That file had
also stopped running entirely: scenarios (a) and (e) built a LazySpan
with no mask around it, which the span now asserts against, so the
benchmark panicked on its second line. Fixed here too.
Also, on Iris's instruction: the copied report no longer inlines a tail
of the app log. Dev Updater's Runtime tab reads the same ring through
devlog's provider, so it was the same lines twice; the diagnostics pane
still names the provider's authority to read them from.
Iris's three points on docs/SCROLL.md, in the shape she proposed: a
controller both scrolling widgets *contain*, rather than a protocol
between them. "I don't like adding methods to widget, it seems like we
can structure things better instead."
`Scroll` becomes `ScrollArea`, because it only scrolls a predefined area.
`ScrollController` holds everything that is not a particular widget's
layout -- the position, the pending delta, the travel left each way, the
pin, the DragGesture and the Flinger -- and `Scrollable` is the trait over
it, one required pair of methods with the rest defaulted.
`Widget` loses `scrolls_itself`, `apply_scroll` and `scroll_offset`. They
existed only so a `Scroll` could drive a `LazySpan` it had no business
wrapping; the span owns its own controller now, so the wrapper, the
measure/apply/place dance between two widgets and `amt`'s two meanings all
go with them. The transcript's tree loses a node: `list` is the layout and
the position.
`.scrollable(axis, pin)` replaces `scrollable`/`scrollable_on`/
`scrollable_to_end` -- one mechanism whose arguments had been hidden in
three names. `LazySpan` has an inherent `scrollable()` that shadows it,
since Rust resolves inherent methods before trait ones: the same word at
the call site, and the wrapping version cannot reach the one widget that
must not be wrapped.
`Pin` says which end either way round: `Start`/`End` are content-relative
and `Neg`/`Pos` axis-absolute, so a caller can say "the bottom" and mean
it whichever way the content runs. They differ only for a reversed span,
which is the whole reason both exist.
One behaviour changes: a delta is applied by the next draw rather than
where it arrives, since the layout is the only thing that knows where the
content ends. Nothing on screen differs -- input is followed by a frame --
but `amt` no longer moves between draws, which several tests were reading.
This also closes SCROLL.md's open question about the pin living in two
places.
Verified: cargo test --workspace (all green, including the layer-1
transcript-fixture fling/selection/top-edge tests), clippy --all-targets
clean, fmt clean, `cargo ndk` check of android-app, and
`run-headless.sh phone --phone --replay flick-120hz.touch`, whose
before/after screenshots show the recorded flick carrying the transcript
back from turn 270 to turn 258 on the Vulkan adapter.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Positive scrolls the reader up or left and negative down or right,
whichever way the widget receiving it lays its content out (Iris,
2026-09-08: "that way it always works as the user would expect").
`LazySpan` took the delta straight into the direction-relative space its
walk works in, so a `Dir::UP` span -- whose later content is *above* --
panned the opposite way from every other scrollable in iris for the same
number. `flip_delta` is the conversion, the counterpart of the `flip_pos`
that positions already went through, and the two places that meet the
outside world (`apply_scroll` and `moved`) are the only ones that use it.
Nothing built a `Dir::UP` span yet, so this was latent; the existing sign
test could not have found it either, since it asserts in the walk's own
space where both halves agree with each other while disagreeing with the
screen. The new test compares the two `dir`s against where rows were
actually drawn.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
For the next session, since this one is about to be cleared. Current
design only -- `Scroll` owns the position, the gesture and the fling; a
child is either moved or answers `Widget::scrolls_itself` and is handed
deltas; one sign convention, the finger's. It carries the things that are
expensive to rediscover and easy to undo by accident: why the two `&self`
capability methods must not be `&mut` (`get_dyn_mut` marks dirty), why
`scroll_offset` exists beside `apply_scroll`'s remainder, why the
measuring draw is free, why nothing is marked by hand, why the height
cache stays in the container, why the transcript builds its `Scroll` by
hand instead of through `.scrollable_to_end()`, and the measured numbers
behind "a `LazySpan` is not a `Span`".
Also names the one thing still open -- the pin -- with the two ways to
close it and an instruction to ask Iris rather than guess.
`scroll.rs` and `lazy_span.rs` now point at it from their module docs
rather than restating it, AGENTS.md lists it beside the other design
documents, and IRIS_TODO.md's in-progress entry defers to it.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Steps 2 and 3 of the plan in docs/IRIS_TODO.md, together because
deleting the fling before `Scroll` could drive it would leave the app
unable to scroll at all. IRIS.md has the account and the measurements.
`LazySpan` loses its `Flinger`, its `density`, its
`Arc<dyn RequestRedraw>` -- which had no business existing in a
single-threaded frame loop -- its `tick`, and the whole
`fling`/`cancel_fling`/`tick_fling`/`is_scrolling`/`fling_velocity`
surface. `Scroll` was the only other `Flinger` user, so there is now one
implementation of the physics rather than two, and a transcript is
`list.scrollable_to_end()` like anything else.
Three new `Widget` methods carry the handoff:
fn scrolls_itself(&self) -> bool { false }
fn apply_scroll(&mut self, delta: &mut f32) {}
fn scroll_offset(&self) -> f32 { 0.0 }
`Scroll` asks the first, and a child that says yes is handed deltas
instead of being slid about as a lump -- which a lazy layout cannot be,
since which rows exist at all is a function of where it is scrolled to,
and it has no content length to be clamped against. `scrolls_itself` is
`&self` deliberately: `Widgets::get_dyn_mut` marks a widget dirty, so
asking through `apply_scroll` would dirty every ordinary child on every
tick and cost exactly the O(1) move the scheme exists for.
`Scroll::draw` is measure, apply, place -- the idiom it already used for
its own content length. The measuring draw is free in the common case
(unchanged region, nothing dirty, `draw_inner` returns immediately and
the child's stored walls are still correct) and really walks exactly
when the content changed. Nothing is marked by hand: reaching the child
to hand it the delta is what dirties it, which is why `draw_again` could
stay deleted.
`scroll_offset` was not in the plan and is needed. A lazy span usually
cannot say where its content ends until it has walked there, so it takes
a delta in full whenever the wall is not already in view and the walk
gives part of it back; the remainder is exact only when the wall was
already visible, and `Scroll` adding remainders up would over-count by
every overshoot and never correct. It reads the child's accumulated
movement after the placing draw instead, so `amt` equals what is on
screen. `amt_counts_only_what_the_child_could_take` is the test.
One convention for a scroll delta, the finger's. `Scroll::scroll(+)`
moved toward the start while `LazySpan::scroll(+)` moved toward the end,
with the latter's doc claiming to mirror the former -- so every call site
had to know which it was talking to. `LazySpan::scroll` is private now
and the single negation is inside its `apply_scroll`; call sites that
passed `-dy`/`-v` pass them through, and `phone_screen.rs`'s recorded
velocity flips sign with its magnitude unchanged.
`a_negative_delta_moves_toward_the_end` pins the sign across the whole
handoff, since nothing else can catch a list scrolling backwards.
The transcript builds its `Scroll` by hand rather than through
`.scrollable_to_end()`: that helper registers a finger drag, and
`Selection` is already the arbiter for those frames -- two `DragGesture`s
seeing one gesture is what its own doc rules out. Caught by
`a_long_press_and_drag_selects_text`, which failed when both were live.
Deferred, in DECISIONS.md and IRIS_TODO.md: the *pin* is still each
widget's own. Applying one happens when a row is appended, between
frames with no painter in hand, so moving it to `Scroll` needs a fourth
`Widget` method or a parameter on `apply_scroll`; nothing external edits
a pin today.
Verified: cargo fmt --check, clippy --workspace --all-targets clean,
cargo test --workspace green (21 suites), the arm64 release APK builds,
and the phone-shaped headless window replaying flick-120hz.touch scrolls
back through the transcript in the direction it did before.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
First of three steps agreed with Iris for getting scrolling out of the
list and into `Scroll`, so that `.scrollable()` is the one way anything
in iris scrolls. docs/IRIS_TODO.md's "In progress" block carries the
whole plan and the decisions behind it; this step is the rename and the
direction.
`List` -> `LazySpan`, and it moves in beside `Span` under
`widget/position/`. It is what `Span` is -- a sequence of children along
an axis -- laid out lazily from an anchor instead of eagerly from the
start, and the name says the one thing that matters about it. It also
stops colliding with `BlockKind::List` in the markdown code.
`ListRow` -> `LazyItem`; `RowKey` keeps its name, since rows are the
vocabulary in transcript-ui.
`Axis` -> `Dir`, with the sign meaning what it means in `Span`: which
end of the box item 0 sits at. **That is a different question from which
end the view is pinned to**, and conflating them would stand a
transcript on its head -- its oldest message is item 0 and sits at the
top (`Dir::DOWN`) while the view clings to the bottom. So the pin is its
own constructor argument, `LazySpan::new(dir, at_end)`, spelled the same
way as `Scroll::new`'s.
Making `Dir::UP` real rather than nominal is most of the diff. The walk
now works entirely in direction-relative pixels from the leading edge --
`Edge::Top`/`Bottom` are `Leading`/`Trailing`, `Placement` likewise, and
`RowExtent`'s fields and every local are `lead`/`trail` -- with two
places converting: `abs_region`, which flips the box for `Sign::Neg`,
and `flip_pos`, which converts the screen-space positions the public
helpers speak in (`note_tap`, `key_at`, `extent`, all fed by pointer
events) into the walk's space. Without the second, a reversed span would
hit-test at the mirror of where it drew.
`a_dir_up_span_grows_upward_from_item_zero` asserts on where each row was
**actually drawn** (`UiRenderState::active`), not on `extents`: the first
version of it read `extent()` and passed with `abs_region`'s flip deleted
-- checking the bookkeeping against itself while every row painted at the
mirror of where it belonged. It now fails with the flip removed (row 2 at
80..100 instead of 0..20), which is the check that matters.
Verified: cargo fmt --check, clippy --workspace --all-targets clean,
cargo test --workspace green (21 suites), including the phone-shaped
fixture tests.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
iris
