iris is the framework alone; the app is one crate in app-rust/

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>

app-rust/tests/phone_screen.rs

@@ -0,0 +1,283 @@
+//! Layer 1 of docs/RUST.md's "Three test layers": the real transcript
+//! screen, over the real bench fixture, at the phone's size and density,
+//! driven by `iris::harness` with no window, no compositor and no GPU.
+//!
+//! Every gesture here is a file under `touch/` -- see
+//! `flick-120hz.touch` for why the *shape* of the delivery is the whole
+//! point, and why the emulator cannot produce it (a `ui-trace` swipe is
+//! many evenly-spaced events; a finger at 120Hz is five samples in
+//! 20ms).
+
+use ai_app::ui::fixture::{PHONE_FRAME_MS, PHONE_SCALE, phone_size};
+use iris::harness::{Harness, TouchScript};
+use iris::prelude::*;
+
+/// The screen open on the fixture, framed twice: once to draw, once for
+/// `LazySpan::repair_anchor` to resolve the opening `snap_end` into a real
+/// anchor, which is what every assertion about scroll position reads.
+fn opened() -> (Harness, ai_app::ui::TranscriptScreen) {
+    let mut h = Harness::new(phone_size(), PHONE_SCALE);
+    let opened = ai_app::ui::fixture::open(&mut h.rsc, &mut h.state).expect("the fixture folds");
+    h.frame(0);
+    h.frame(PHONE_FRAME_MS);
+    (h, opened.screen)
+}
+
+fn script(name: &str, text: &str) -> TouchScript {
+    TouchScript::parse(text).unwrap_or_else(|e| panic!("{name}: {e}"))
+}
+
+fn offset(h: &mut Harness, screen: &ai_app::ui::TranscriptScreen) -> String {
+    (screen.list)(&mut h.rsc).anchor_position_display()
+}
+
+/// (a) and (b) together, because the second is only meaningful if the
+/// first happened: the recorded flick must release with a real velocity
+/// (`GestureOutcome::Released(Some(v))`, which is the only thing that
+/// puts a value in `Scroll::fling_velocity`), and the list must then
+/// actually travel and stop on the spline's own schedule.
+#[test]
+fn a_recorded_flick_releases_with_a_velocity_and_flings_the_list() {
+    let (mut h, screen) = opened();
+    let before = offset(&mut h, &screen);
+
+    let flick = script("flick-120hz", include_str!("../touch/flick-120hz.touch"));
+    h.replay(&flick);
+
+    let velocity = (screen.list)(&mut h.rsc)
+        .fling_velocity()
+        .expect("the flick must release as a pan with a velocity, not a tap");
+    // Compose's own answer for this recording's five samples, printed by
+    // `iris/benches/velocity_reference.py` -- not a number read off this
+    // code. **Positive** because the flick runs *down* the screen and a
+    // delta now carries the finger's own direction the whole way, from the
+    // gesture through `Selection::drag` (which passes it straight to
+    // `Scroll::fling`) to the anchor. It read -15250 while the transcript
+    // negated the velocity on its way into a `LazySpan` whose anchor
+    // offset ran the other way; the magnitude is the number that came from
+    // `velocity_reference.py` and it has not changed.
+    // The 2026-09-07 before/after: the old average estimator read
+    // 12250px/s here, which is the fling Iris reported as too slow.
+    assert!(
+        (velocity - 15_250.0).abs() < 20.0,
+        "expected ~15250px/s from velocity_reference.py, got {velocity}"
+    );
+
+    // `iris/benches/fling_spline_reference.py`'s own line for this exact
+    // case -- `density=2.55 v=15250.0: distance=11057.424px
+    // duration=2.0716s`. **Not** `FlingCalculator::new(PHONE_SCALE)`,
+    // which is the calculator under test: bounding a fling with the thing
+    // being measured is the "compared the code with itself" shape 73f956f
+    // found in the spline's own tests, and it left this one able to fail
+    // in the "ran too long" direction only -- never in the "stopped dead"
+    // direction, which is what Iris actually reported
+    // (docs/REVIEW-2026-09-07.md's T1).
+    const REFERENCE_MS: u64 = 2071;
+    const REFERENCE_PX: f32 = 11057.0;
+    let end = flick.end_ms() + REFERENCE_MS * 2;
+    let mut settled_at = None;
+    let mut t = flick.end_ms();
+    // Travel in pixels, measured from a row's own on-screen extent, since
+    // `LazySpan` has no travel accessor and this needs none: follow whatever
+    // row is under the viewport's middle until it leaves, then pick
+    // another. Deliberately an *under*-count -- the frame a row leaves on
+    // contributes nothing -- which is why it is only ever a lower bound.
+    let middle = phone_size().y / 2.0;
+    let mut travelled = 0.0f32;
+    let mut tracked: Option<(RowKey, f32)> = None;
+    while t <= end {
+        h.frame(t);
+        let list = (screen.list)(&mut h.rsc);
+        tracked =
+            match tracked.and_then(|(key, was)| list.extent(key).map(|(now, _)| (key, was, now))) {
+                Some((key, was, now)) => {
+                    travelled += (now - was).abs();
+                    Some((key, now))
+                }
+                None => list
+                    .key_at(middle)
+                    .and_then(|key| list.extent(key).map(|(top, _)| (key, top))),
+            };
+        if settled_at.is_none() && !(screen.list)(&mut h.rsc).is_scrolling() {
+            settled_at = Some(t);
+        }
+        t += PHONE_FRAME_MS;
+    }
+
+    let after = offset(&mut h, &screen);
+    assert_ne!(
+        before, after,
+        "the fling ticks must have moved the list off where the flick left it"
+    );
+    let settled_at = settled_at.expect("the fling must stop on its own, not run forever");
+    let ran_for = settled_at - flick.end_ms();
+    // Both directions. The lower bound is the one that fails when a fling
+    // settles on its first tick; the upper is the one that was here.
+    assert!(
+        ran_for >= REFERENCE_MS - PHONE_FRAME_MS * 2,
+        "the fling stopped after {ran_for}ms against the spline reference's {REFERENCE_MS}ms"
+    );
+    assert!(
+        ran_for <= REFERENCE_MS + PHONE_FRAME_MS * 2,
+        "the fling ran {ran_for}ms against the spline reference's {REFERENCE_MS}ms"
+    );
+    // 80% of the reference, against 10527px measured today -- the 5%
+    // shortfall is the frames a tracked row leaves the screen on. A fling
+    // that moves one row's worth fails this; scaling `tick_fling`'s delta
+    // by 0.01 reports 111px, which is how it was confirmed to fail in the
+    // direction the bug goes.
+    assert!(
+        travelled >= REFERENCE_PX * 0.8,
+        "the fling travelled {travelled:.0}px against the spline reference's {REFERENCE_PX:.0}px"
+    );
+}
+
+/// The half the flick fix had no reason to touch: a tap must decide
+/// `Tapped`, which means no velocity anywhere and nothing moved.
+#[test]
+fn a_tap_on_a_row_moves_nothing() {
+    let (mut h, screen) = opened();
+    let before = offset(&mut h, &screen);
+
+    h.replay(&script("tap", include_str!("../touch/tap.touch")));
+
+    assert_eq!(
+        (screen.list)(&mut h.rsc).fling_velocity(),
+        None,
+        "a tap must not fling"
+    );
+    // Frames it would have moved in, had anything been moving.
+    h.frames_until(100, 400, PHONE_FRAME_MS);
+    assert_eq!(before, offset(&mut h, &screen), "a tap must scroll nothing");
+    assert_eq!(
+        h.state.opened_urls,
+        Vec::<String>::new(),
+        "no link was under this tap"
+    );
+}
+
+/// A press held past `LONG_PRESS` and then dragged selects text rather
+/// than panning -- the other branch of the same arbiter the flick goes
+/// through.
+#[test]
+fn a_long_press_and_drag_selects_text() {
+    let (mut h, screen) = opened();
+    let before = offset(&mut h, &screen);
+
+    h.replay(&script(
+        "long-press",
+        include_str!("../touch/long-press.touch"),
+    ));
+
+    let selected = screen
+        .selected_text(&mut h.rsc)
+        .expect("a long-press then drag must leave text selected");
+    assert!(
+        !selected.trim().is_empty(),
+        "the selection covered no characters: {selected:?}"
+    );
+    assert_eq!(
+        before,
+        offset(&mut h, &screen),
+        "a selection must not also pan the list"
+    );
+}
+
+/// The composer sits on whatever the platform says the bottom of usable
+/// space is -- the keyboard's inset while it is open
+/// (`Composer::set_bottom_inset`, the path Android's
+/// `on_insets_changed` feeds). Checked here rather than on the emulator
+/// because it is a layout fact, and the emulator costs minutes.
+#[test]
+fn the_composer_sits_above_a_simulated_ime_inset() {
+    let (mut h, screen) = opened();
+    let height = h.size().y;
+    let field_bottom = |h: &mut Harness| {
+        h.render
+            .window_region(&screen.composer.field, &h.rsc)
+            .expect("the composer field is on screen")
+            .bot_right
+            .y
+    };
+
+    let closed = field_bottom(&mut h);
+    assert!(
+        closed <= height,
+        "the composer is off the bottom of the window even with no keyboard: {closed} > {height}"
+    );
+
+    // A Gboard-sized keyboard on this surface. Any real number would do;
+    // what matters is that the bar clears it.
+    let ime = 1000.0;
+    screen.composer.set_bottom_inset(&mut h.rsc, ime);
+    h.frame(PHONE_FRAME_MS * 2);
+
+    let open = field_bottom(&mut h);
+    assert!(
+        open <= height - ime,
+        "the keyboard covers the composer: its bottom is at {open}, the IME starts at {}",
+        height - ime
+    );
+    assert!(
+        (closed - open - ime).abs() < 1.0,
+        "the composer moved {} for a {ime}px inset",
+        closed - open
+    );
+}
+
+/// A newline typed into the composer must leave the caret inside the
+/// bar's own padding, not flush against its bottom edge.
+///
+/// Iris's phone, 2026-09-08: "when typing with the keyboard up and
+/// entering enough newlines ... the text drops down close to the bottom
+/// and seems to ignore the padding. If I close (and optionally reopen)
+/// the keyboard it seems to fix itself." The cause was `Scroll::draw`
+/// placing its child against *last* frame's content length and stopping
+/// there: each newline drew the field in a box one line short of its
+/// text, and since the text is centred in its box it hung half a line
+/// past each end, putting the caret's line box a full padding below the
+/// bar's inside edge. Nothing dirtied that subtree again, so the stale
+/// placement was simply the last one drawn -- until the keyboard closed
+/// and the inset rewrite forced a redraw, which is the "fixes itself"
+/// half of the report. No settling frame here on purpose: the placement
+/// is corrected within the frame that typed, so the first frame drawn
+/// after a keystroke is already right.
+#[test]
+fn a_newline_leaves_the_caret_inside_the_composers_padding() {
+    let (mut h, screen) = opened();
+    let height = h.size().y;
+    let ime = 1000.0;
+    screen.composer.set_bottom_inset(&mut h.rsc, ime);
+    h.frame(PHONE_FRAME_MS * 2);
+
+    h.state.set_focus(Some(screen.composer.field));
+    screen.composer.field.edit(&mut h.rsc).set_cursor_byte(0);
+    // Past `composer::MAX_LINES`, so the bar is capped and scrolling
+    // rather than still growing -- the state the report is about.
+    for _ in 0..12 {
+        screen.composer.field.edit(&mut h.rsc).insert("a\n");
+        h.frame(PHONE_FRAME_MS);
+    }
+    // The caret is the last primitive `TextEdit::draw` emits.
+    let caret = {
+        let slot = *h
+            .render
+            .debug(h.rsc.widgets(), "Message")
+            .flat_map(|a| a.primitives.iter().map(|p| p.slot))
+            .collect::<Vec<_>>()
+            .last()
+            .expect("the focused field draws a caret");
+        h.render.primitive_corners(slot, &h.rsc)
+    };
+    // The bar sits directly on the IME, so its inside edge is one
+    // `FIELD_PAD_DP` above `height - ime`. Stated in pixels rather than
+    // read back from the composer, which is the thing under test.
+    let bar_bottom = height - ime;
+    let padding = 12.0 * PHONE_SCALE;
+    assert!(
+        caret.bot_right.y < bar_bottom - padding / 2.0,
+        "the caret is in the bar's bottom padding: it ends at {}, the bar's edge is {bar_bottom} \
+         and its padding is {padding}px",
+        caret.bot_right.y,
+    );
+}