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/fence_fling.rs

@@ -0,0 +1,230 @@
+//! Layer 1 for Iris's 2026-09-08 "flinging doesn't work in horizontal
+//! scroll areas": a real markdown fence in the real transcript screen,
+//! flicked sideways, has to keep moving after the finger leaves.
+//!
+//! The fence is pushed here rather than hunted for in the bench fixture,
+//! so the test knows which row it is pressing and where. The `ScrollArea` it
+//! asserts on is found by walking what is actually drawn -- there is no
+//! handle to it from the outside, and a coordinate would only prove that
+//! *something* moved.
+
+use ai_app::ui::fixture::{PHONE_FRAME_MS, PHONE_SCALE, phone_size};
+use iris::harness::{Harness, TouchAction};
+use iris::prelude::*;
+
+/// The horizontal scroll area drawn inside `top..bottom`, with the box
+/// it was drawn at -- a fence is the only thing in a transcript that pans
+/// sideways. Found by walking what is actually drawn, because there is no
+/// handle to a fence's own `ScrollArea` from the outside and a bare
+/// coordinate would only prove that *something* moved.
+fn fence_scroll_in(h: &Harness, top: f32, bottom: f32) -> Option<(WidgetId, PixelRegion)> {
+    h.render
+        .active
+        .keys()
+        .copied()
+        .filter(|&id| {
+            h.rsc
+                .ui
+                .widgets
+                .get_dyn(id)
+                .and_then(|w| w.as_any().downcast_ref::<ScrollArea>())
+                .is_some_and(|s| s.axis() == Axis::X)
+        })
+        .find_map(|id| {
+            let r = h.render.window_region(&id, &h.rsc)?;
+            (r.top_left.y >= top && r.bot_right.y <= bottom).then_some((id, r))
+        })
+}
+
+fn is_scrolling(h: &Harness, id: WidgetId) -> bool {
+    h.rsc
+        .ui
+        .widgets
+        .get_dyn(id)
+        .and_then(|w| w.as_any().downcast_ref::<ScrollArea>())
+        .expect("the fence's scroll area is still drawn")
+        .is_scrolling()
+}
+
+fn amt(h: &Harness, id: WidgetId) -> f32 {
+    h.rsc
+        .ui
+        .widgets
+        .get_dyn(id)
+        .and_then(|w| w.as_any().downcast_ref::<ScrollArea>())
+        .expect("the fence's scroll area is still drawn")
+        .amt()
+}
+
+#[test]
+fn a_flick_across_a_code_fence_keeps_moving_after_the_finger_leaves() {
+    use ai_app::client::transcript_fold::{TranscriptItem, TranscriptRow};
+
+    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");
+    let screen = opened.screen;
+    h.frame(0);
+    h.frame(PHONE_FRAME_MS);
+
+    let fence = TranscriptRow::Single(TranscriptItem::AssistantMsg {
+        seq: 9_000_000,
+        text: "```\none two three four five six seven eight nine ten eleven twelve \
+               thirteen fourteen fifteen sixteen seventeen eighteen twenty twentyone\n```"
+            .to_string(),
+        settled: true,
+    });
+    screen.push_row(&mut h.rsc, &fence);
+    (screen.list)(&mut h.rsc).jump_to_end();
+    h.frame(100);
+    h.frame(108);
+
+    let key = ai_app::ui::row::row_key(&fence.key());
+    let (top, bottom) = (screen.list)(&mut h.rsc)
+        .extent(key)
+        .expect("the fence row is on screen");
+    let (fence_scroll, box_) = fence_scroll_in(&h, top, bottom)
+        .expect("the pushed fence draws a horizontal scroll area of its own");
+    assert_eq!(amt(&h, fence_scroll), 0.0, "a fence opens at its start");
+
+    // Down the middle of the fence's own box, so the press is on the
+    // text inside the scroll area rather than on the row's sender label.
+    let y = (box_.top_left.y + box_.bot_right.y) / 2.0;
+
+    // A flick sideways: four samples 8ms apart, accelerating, then the
+    // finger leaves.
+    h.touch(TouchAction::Down, Vec2::new(900.0, y), 200);
+    for (i, x) in [860.0, 800.0, 720.0, 620.0].into_iter().enumerate() {
+        h.touch(TouchAction::Move, Vec2::new(x, y), 208 + 8 * i as u64);
+    }
+    h.touch(TouchAction::Up, Vec2::new(620.0, y), 240);
+
+    let at_release = amt(&h, fence_scroll);
+    assert!(
+        at_release > 0.0,
+        "the flick itself must have panned the fence, got {at_release}"
+    );
+
+    // Frames for the next half second, with nothing touching the screen.
+    let mut t = 240;
+    while t <= 740 {
+        h.frame(t);
+        t += PHONE_FRAME_MS;
+    }
+    let coasted = amt(&h, fence_scroll);
+    assert!(
+        coasted > at_release + 1.0,
+        "the fence stopped dead at the release: {at_release} -> {coasted}"
+    );
+
+    // ...and it settles rather than running forever.
+    let settled = coasted;
+    while t <= 4_000 {
+        h.frame(t);
+        t += PHONE_FRAME_MS;
+    }
+    let after = amt(&h, fence_scroll);
+    assert!(
+        after >= settled,
+        "a fling must not run backwards: {settled} -> {after}"
+    );
+    let last = after;
+    h.frame(t);
+    assert_eq!(last, amt(&h, fence_scroll), "the fling never settled");
+}
+
+/// Iris's 2026-09-08 report: "if I try to scroll vertically while a
+/// horizontal scroll animation is still active, it stays locked to the
+/// horizontal scroll. It should let it keep going and instead only affect
+/// vertical scrolling."
+///
+/// Her own diagnosis was the right one -- "tapping outside of something
+/// that a fling is currently active for should have no code in common
+/// with the fling that could influence it" -- and
+/// `sense_tests::a_press_does_not_reach_a_widget_the_pointer_has_just_left`
+/// is the mechanism in isolation. This is the same thing over the real
+/// screen, which is where it was found: the finger goes down on an
+/// ordinary row 500px above a coasting fence, and what must move is the
+/// list, while the fence carries on coasting untouched.
+#[test]
+fn a_drag_away_from_a_coasting_fence_scrolls_the_list_and_leaves_it_coasting() {
+    use ai_app::client::transcript_fold::{TranscriptItem, TranscriptRow};
+
+    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");
+    let screen = opened.screen;
+    h.frame(0);
+    h.frame(PHONE_FRAME_MS);
+
+    let fence = TranscriptRow::Single(TranscriptItem::AssistantMsg {
+        seq: 9_000_000,
+        text: format!(
+            "```\n{}\n```",
+            (1..=200)
+                .map(|i| format!("word{i}"))
+                .collect::<Vec<_>>()
+                .join(" ")
+        ),
+        settled: true,
+    });
+    screen.push_row(&mut h.rsc, &fence);
+    (screen.list)(&mut h.rsc).jump_to_end();
+    h.frame(100);
+    h.frame(108);
+
+    let key = ai_app::ui::row::row_key(&fence.key());
+    let (top, bottom) = (screen.list)(&mut h.rsc)
+        .extent(key)
+        .expect("the fence row is on screen");
+    let (fence_scroll, box_) = fence_scroll_in(&h, top, bottom)
+        .expect("the pushed fence draws a horizontal scroll area of its own");
+    let y = (box_.top_left.y + box_.bot_right.y) / 2.0;
+
+    // Flick the fence sideways and let go, exactly as above.
+    h.touch(TouchAction::Down, Vec2::new(900.0, y), 200);
+    for (i, x) in [860.0, 800.0, 720.0, 620.0].into_iter().enumerate() {
+        h.touch(TouchAction::Move, Vec2::new(x, y), 208 + 8 * i as u64);
+    }
+    h.touch(TouchAction::Up, Vec2::new(620.0, y), 240);
+    h.frame(248);
+    assert!(
+        is_scrolling(&h, fence_scroll),
+        "the fence has to still be coasting for this to be the reported case",
+    );
+
+    // A row well clear of the fence, taken by its own extent rather than
+    // by a coordinate: the gaps between rows are pointer-transparent, so a
+    // y picked by hand lands on nothing often enough to make a green run
+    // meaningless.
+    let probe = box_.top_left.y - 500.0;
+    let row = (screen.list)(&mut h.rsc)
+        .key_at(probe)
+        .expect("a row that far up the screen");
+    let (row_top, row_bottom) = (screen.list)(&mut h.rsc).extent(row).expect("its extent");
+    let from = (row_top + row_bottom) / 2.0;
+
+    let list_before = (screen.list)(&mut h.rsc).anchor_position_display();
+    let fence_before = amt(&h, fence_scroll);
+    h.touch(TouchAction::Down, Vec2::new(540.0, from), 256);
+    let mut t = 264;
+    for i in 1..=8 {
+        h.touch(
+            TouchAction::Move,
+            Vec2::new(540.0, from + 20.0 * i as f32),
+            t,
+        );
+        t += 8;
+    }
+    h.touch(TouchAction::Up, Vec2::new(540.0, from + 160.0), t);
+
+    assert_ne!(
+        list_before,
+        (screen.list)(&mut h.rsc).anchor_position_display(),
+        "the drag was nowhere near the fence, so it belongs to the list",
+    );
+    assert!(
+        amt(&h, fence_scroll) > fence_before,
+        "the fence's fling must carry on through a gesture that was never \
+         its own: {fence_before} -> {}",
+        amt(&h, fence_scroll),
+    );
+}