# iris: known problems and things still to build Iris's own list for the library, recorded 2026-09-04 in her words where it matters, so the agents working through RUST.md pick these up in a sensible order rather than rediscovering them. Each item says where it sits in the order and what "done" looks like. Tick and date them in place. ## Fix - [x] **Input does not fall through by input type (2026-09-04).** `SensorUi::run_sensors` (`src/default/sense.rs`) used to set "consumed, stop checking lower layers" from mere hover — a widget registered for nothing but `click()` blocked a `Scroll` meant for whatever was behind it, since "the cursor is over this widget" and "this widget handled the event" were the same check. Fixed by judging consumption per input kind: with no button transition and no scroll happening this frame ("momentary" activity), the topmost hovered widget still wins, same as before; when something momentary *is* happening, only a widget whose registered senses actually include a matching non-hover one (checked via a new `TypeEventManager::registered`, which lists what a widget registered without running anything) consumes it, so a widget with only `Hovering`/click handlers can no longer block a scroll from reaching a list underneath. `iris/src/sense_tests.rs` builds a button-over-a-list `Stack` with a plain `HasEvents` impl (no GPU or window) and checks both directions: a scroll over the button reaches the list, and a real click still reaches the button — confirmed to fail on the pre-fix code and pass after. - [x] **Appending one image to an already-loaded list rebuilds every other image's bind group (2026-09-05, fixed 2026-09-05).** Found by the benchmark below: `GpuTextures::update` (`core/src/render/texture.rs`) triggered `rebuild_image_bind_groups` — a loop over *every live standalone image*, rebuilding its `BindGroup` — whenever the shared `masks` or `move_offsets` GPU buffer was resized (`masks_resized || moves_resized` in `UiRenderNode::update`, `core/src/render/mod.rs`), and a widget getting its *first* move-offset slot (LAYOUT.md section 2 — every widget gets one on first draw) could be exactly what grows that buffer. So one new message with one new image, appended to a transcript that already has N images loaded, did not cost O(1): it cost one `create_image` for the new image plus one `make_image_bind_group` per *existing* image, because the new widget's own move slot pushed the arena past its capacity. Measured directly in `iris/examples/bench_images.rs`: appending a 1,001st image to 1,000 already-settled ones reported **1,001** bind-group creates for that one frame, not 1 (`./run-bench.sh images`, frame 5 in the transcript below). **Fix**: `masks`/`move_offsets` never belonged in a standalone image's own bind group (group 2) in the first place — the group also holds that image's own texture view, which is the only thing that is genuinely per-image, so a buffer shared by *everything* forced a rebuild of *every* group the moment it moved. Gave masks/move_offsets their own bind group (group 3 in `shader.wgsl` and `UiRenderNode`: `masks_layout`/ `masks_group`), bound once per frame in `UiRenderNode::draw` rather than once per draw call, instead of duplicating them into every per-image group. `GpuTextures` and its image bind groups now know nothing about either buffer — `rebuild_image_bind_groups` is called only from `grow_array` (the atlas array texture growing, which genuinely does change what every image's own bind group must reference) — so a masks/move_offsets resize now touches exactly one bind group, ever, regardless of how many images are live. Numbers after the fix, same benchmark and command: ./run-bench.sh images frame=1 bind_group_creates=1000 (cold load, unchanged) frame=2 bind_group_creates=0 (was 1000 -- see the item below) frame=3 bind_group_creates=0 frame=4 bind_group_creates=0 (append one image here) frame=5 bind_group_creates=1 (was 1001) frame=6 bind_group_creates=0 `run-headless.sh tabs --shot` still 27266 bytes, byte-for-byte unchanged, confirming the bind-group restructuring changed nothing about what is drawn. - [x] **Bind-group creation takes two frames to reach the steady state, not one (2026-09-05, closed by the fix above, 2026-09-05).** Same benchmark: loading 1,000 images cold used to report 1,000 creates on frame 1 (expected — `create_image`, one per new image) *and again* 1,000 on frame 2, before settling to 0 from frame 3. This was `rebuild_image_bind_groups` firing a second time for the same masks/move-offsets buffer-growth reason as the item above, confirming the guess recorded here — the two were exactly the same root cause measured two different ways. Frame 2 now reports 0 (see the numbers above); not a separate fix. - [ ] **A read-only text display has no widget of its own — P0's bench report area is a `TextEdit` standing in for one (2026-09-05).** The only way to get selectable text on screen today is `.editable(...)` plus `.attr::(())` (`Selectable` is only implemented for `TextEdit`, `iris/src/attr.rs`), which also makes the field focusable — tapping the bench report opens the soft keyboard over text nothing lets you type into. Harmless for a bench-only debug screen (not fixed this pass), but a real "selectable, not editable" text primitive would remove the keyboard side effect and is worth having before another screen wants the same thing (P1's own transcript rows already read their content from a `TextEdit` for the same reason). ## Build - [x] **Benchmarks**, not unit tests, run on demand (2026-09-05; a `benches/` or a script under `iris/`, never in `cargo test`). The scenario that matters most is a **message list** — chat apps and this app's transcript alike — stressed with many messages and many images. One case in particular: **resizing an input box** (typing enough text to grow it) that pushes a long list of messages above it must stay very fast and recalculate almost nothing — a move of everything above, not a re-layout. That is exactly the O(1) move chain in LAYOUT.md; the benchmark is what proves it. Done when the numbers are in this file with the command, and the input-box case reports draws re-run, not just frame time. **Built as two rigs**, chosen per scenario by whether a real `wgpu` device is needed (`UiRenderState`/`Widgets` touch no GPU or window, so most of this runs as an ordinary binary — the same property `layout_tests.rs` relies on): - `iris/benches/message_list.rs` — a plain `Instant`-timed binary (`[[bench]] harness = false` in `iris/Cargo.toml`), not criterion: see the file's own header for why (short version — every scenario here reduces to a *count* `UiRenderState::take_counters` already produces, which criterion's statistical machinery adds nothing to and which a new dependency is not worth pulling in for). Covers (a) first-frame cost of a message list of N wrapped-text rows (one in 20 also carrying a small in-memory image) for N = 100/1,000/10,000; (b) per-frame cost of scrolling that list, 200 ticks; (c) the input-box case — a fixed-height field at the bottom of the screen growing by a line 40 times, with the message list above it filling the rest of the screen. Run: `cd iris && cargo bench --bench message_list` (always release — `cargo bench` builds the `bench` profile, which is optimized). - `iris/examples/bench_images.rs` — needs a real device, so it runs through `iris/run-headless.sh bench_images`, printing `UiRenderNode::take_image_bind_group_creates()` (a new counter, added in `core/src/render/texture.rs` and `core/src/render/mod.rs`, mirroring `UiRenderState::take_counters`) each frame. Covers (d): 1,000 image rows, checked both cold (does bind-group creation reach zero once loaded) and after appending one more image once settled (does *that* stay cheap) — the second question is what actually matters for a live transcript and is what turned up the two Fix items above. - `iris/run-bench.sh [list|images]` runs either or both and is what to run before/after touching `Scroll`, `Span`, `Sized`, the move-offset chain, or `GpuTextures`. **Numbers (2026-09-05, release, `cargo bench`/`run-headless.sh`, this VM: AMD Ryzen 7 3800X, 8 cores, rustc 1.98.0 nightly-2026-09-03):** cd iris && cargo bench --bench message_list (a) first frame, N=100: 30.30ms draws=227 rewrites=15 moves=0 (a) first frame, N=1000: 186.04ms draws=2252 rewrites=150 moves=0 (a) first frame, N=10000:1770.36ms draws=22502 rewrites=1500 moves=0 (b) scroll, N=100/1000/10000, 200 ticks each: draws=200 rewrites=0 moves=200 (identical at every N) per-tick average: 0.0002ms (identical at every N) (c) input grows 40 lines, N=100/1000/10000 rows above it: draws=320 rewrites=40 moves=160 (identical at every N) per-line average: 0.0012-0.0013ms (identical at every N) cd iris && ./run-bench.sh images (2026-09-05, before the fix) frame=1 bind_group_creates=1000 (cold load) frame=2 bind_group_creates=1000 (see Fix item above) frame=3 bind_group_creates=0 frame=4 bind_group_creates=0 (append one image here) frame=5 bind_group_creates=1001 (see Fix item above) frame=6 bind_group_creates=0 cd iris && ./run-bench.sh images (2026-09-05, after the fix) frame=1 bind_group_creates=1000 (cold load, unchanged -- genuine work) frame=2 bind_group_creates=0 frame=3 bind_group_creates=0 frame=4 bind_group_creates=0 (append one image here) frame=5 bind_group_creates=1 (one image's own create_image, O(1)) frame=6 bind_group_creates=0 **Reading it**: (a) is real, necessary work — shaping and laying out N never-before-seen text rows — and scales with N as it must, ~10x cost per 10x N. (b) and (c) are the pass conditions that matter: both are **exactly flat across N = 100 to 10,000**, confirming LAYOUT.md's O(1) move chain holds for both scrolling and for a growing input box pushing the message list — draws/moves per tick or per line do not grow with list size, and the per-operation cost (a fraction of a microsecond) is nowhere near a frame budget. (d)'s cold-load and steady-state halves behave as designed; its *append* half did not, until the fix above moved masks/move_offsets out of the per-image bind group — now flat at O(1) the same way (b) and (c) are. - **I5's transcript screen (`iris/transcript-ui/`, 2026-09-05) — what it left, each recorded at the point in the code it would go rather than silently dropped. See RUST.md's I5 box for the full account of what *was* built (the screen, `SpanStyle`, cross-row selection, the growing composer).** - [x] **Android integration for this screen — done, 2026-09-05.** `iris-android-app`'s `transcript-screen` Cargo feature (`transcript_client.rs`) runs this screen against a real `ai-server` through `client-core`, confirmed on-device: real scrolling, real touch-drag panning, tap-by-name on the composer. Two real bugs found and fixed along the way (a missing `INTERNET` permission; a background-thread redraw request that crashed via a `Looper` requirement, fixed by routing through `View::post_delayed` — see `IRIS.md`'s `Tasks::redraw_handle` entry). See RUST.md's I5 box, "The Android integration, done 2026-09-05" for the full account. - [x] **A render-time number for iris, comparable to Compose's `transcript-bench.sh` report — instrumentation done and a real number obtained, 2026-09-05 (later the same day); the clean comparable loop is not.** `iris_core::FrameReport` (`iris/core/src/render/ frame_report.rs`, `IRIS.md`'s new entry) times every frame from `render()`'s redraw start to after `queue.submit`+`present()`, exposed as two named on-screen controls ("Frame report", "Reset frame report"). Driven against a real on-device touch-drag it read `frames=34 janky%=61.76 p50=26.5ms p90=48.0ms p99=98.1ms worst=98.1ms` — real, not inferred, but accumulated across several gestures rather than one clean 24-swipe loop, because of the new finding below. See RUST.md's I5 box, "Update, 2026-09-05, later the same day" for the full account. - [ ] **New, 2026-09-05: intermittent touch delivery to iris's `SurfaceView` under this checkout's `EMU_GPU=software` emulator.** The same swipe coordinates, confirmed (by scanning a screenshot column for the first non-black pixel) to sit over real row text, sometimes produced 30+ real frames and a screenshot diff and sometimes produced zero of either, across otherwise-identical `ui-trace` invocations. Not the already-understood "already at that scroll edge" case (reproduced with content confirmed taller than the viewport, in both directions). Leading candidate, not yet confirmed: this checkout's emulator was independently observed at ~78% of one CPU core, continuously, while idle on-screen — SwiftShader's software rasterisation is CPU-bound by design, and a synthetic touch competing with that load for delivery is plausible but unmeasured *during* a failing gesture (the standing rule against diagnosing from after-the-fact measurements applies here). Needs a sampler (load, `dumpsys input`, a `-i 0` `ui-trace` capture) running while a failing gesture is driven, and ideally a comparison under `-gpu host` (real Vulkan) to see whether it is specific to software rendering. This is what blocks the clean, comparable 24-swipe loop above. - [x] **Long-press-then-drag-to-select — confirmed on-device, 2026-09-05 (later the same day).** `ui-trace` gained a `holddrag X1 Y1 X2 Y2 HOLD_MS MOVE_MS` action (`emulator-tools`, additive, extends the same `MotionEvent`/`injectInputEvent` mechanism `swipe` already used): press, hold past `LONG_PRESS`, move, release, as one continuous touch. Driven against a real row (`holddrag 300 1850 300 2050 600 300`) it produced `iris selection: begin at row ...` then a sequence of `iris selection: extend to row ...` log lines (`transcript-ui/src/selection.rs`, a new small `log` dependency since selection has no accessibility label of its own yet — see the next item), and a screenshot taken right after shows the expected highlighted selection spanning multiple rows. `DragArbiter`'s own unit tests already covered this sequence against a synthetic clock; this is the first time it has been driven by a real device touch. - [x] **Touch-drag panning over a row's own rendered text — done, 2026-09-05.** `row.rs` used to register `CursorSense::click_or_drag()` on each row's `TextEdit` for cross-row selection; `TextEdit::draw`'s `painter.child_layer()` (`iris/src/widget/text/edit.rs:87`) meant that registration won `core/src/sense.rs::run_sensors`'s per-layer arbitration on every frame it was pressed, not just the frame the press started, so a list pan gesture registered on `List` itself never got a turn while a row was under the finger. Fixed with `iris::sense::DragArbiter` (recorded in `IRIS.md`), one small state machine per list deciding pan vs. select the way Android does (a vertical drag pans immediately; a stationary press held `LONG_PRESS` (500ms) starts a selection which further drag extends; a horizontal drag while something is already selected extends immediately) — `transcript-ui/src/selection.rs`'s `Selection::drag` is the one place every row's drag now routes through. 8 new unit tests (`iris/src/sense.rs`'s `drag_arbiter_tests`); `cargo fmt/clippy/test --workspace` and `cargo ndk` (both `iris` and `transcript-ui`) all clean; `run-headless.sh` screenshot byte-identical to before the change (38578 bytes). See RUST.md's I5 box, "Gap closed, 2026-09-05". - [x] **Intermittent touch-scroll dropout — root-caused and fixed, 2026-09-05.** Not the coalesced-`ACTION_MOVE` hypothesis the earlier pass suspected (ruled out): a gesture's `ACTION_DOWN` can land on a row's own padding/gap or its header, which no `CursorSense` covers, so `DragArbiter` never gets `press_start` and sits in `Idle` (answers `Undecided` forever) for that whole gesture. Fixed via a new `DragArbiter::is_idle()` that `Selection::drag` (`transcript-ui/src/selection.rs`) checks to recover a missed press on the next `Pressing` frame. Four new unit tests. See RUST.md's I5 box, "Touch-scroll dropout root-caused, 2026-09-05", for the trace and what a peer session sharing this checkout's emulator mid-pass prevented from being re-verified end-to-end (the aggregate `iris-scroll.sh` three-run confirmation and a re-taken FrameReport row) — a future pass should finish that once the emulator is free. - [ ] **Row-level accessibility names.** The composer carries `.label("Message")`; transcript rows do not carry a `.label()` of their own yet, so `Widgets::named()` (I4) does not include them — `row.rs`'s `build_text_row` is where one would go, keyed to something stable per row (its sender + a short excerpt, matching what a screen reader announcing a chat message would say). - [ ] **A tappable link and a background chip behind inline code.** Both need per-range glyph geometry that `TextEditCtx` does not expose outside `iris::widget::text` (`edit.rs`'s `layout()` helper is private) — see `markdown.rs`'s module doc for the exact shape the fix would take (the same primitive `TextEdit::draw`'s own selection highlight already uses internally, `iris/src/widget/text/edit.rs:99`). - [ ] **`Selection`'s anchor-row shortcut.** The row a drag started in is selected in full (`select_all`) the moment the drag leaves it, rather than "from the click point to whichever edge points away from the drag" — needs the same private `layout()` access as the item above. `selection.rs`'s module doc has the exact reasoning. - [ ] **No syntax highlighting inside a fenced code block.** `client_core::highlight` exists (built for the file explorer) and could feed per-token `SpanStyle`s into a code block's span; wiring it in was not attempted this pass. - [ ] **Masks defined relative to each other.** Wanted: mask A multiplies by something *and also* applies mask B — a mask can reference a parent mask, the way the move chain references a parent offset. Today masks are independent regions. Design it beside the move chain (same shape: a parent index and a bounded walk in the shader); do it when a real widget needs it, not before. - [ ] **Positions as a single float per scroll.** Iris raised, and half rejected, letting a scroll update one float rather than positions: input handling cares about most elements in a list, so absolute positions must be computed on the CPU anyway. LAYOUT.md's design already lands here (GPU walks the chain, CPU resolves on demand for hit tests). Keep the CPU resolution lazy and per query; do not materialise every row's absolute position per frame. - [ ] **Animations, last.** Cosmetic, so after everything above. Must be **modular — a piece of the library rather than a core part forced into everything, the same way input is**. Whatever the mechanism, a widget that does not animate must pay nothing and import nothing for it. ## Build (for the port) Widgets `RUST.md`'s "The port, in order (decided 2026-09-05)" needs and iris does not have yet, one entry per gap, named against the P-step that first needs it. Move an entry up to "Fix" or tick it in place once built; do not duplicate it there. - [ ] **A history-paging cushion measured in on-screen viewports, not a row count.** (**P1**.) `iris::widget::List` has no equivalent of the Compose app's `HISTORY_SCREENS` — AGENTS.md's "Things that have bitten" is explicit that a fixed row count under-fills a screen on a tool-heavy transcript and over-fills one on a text-heavy one, so whatever loads the next page has to ask the list how many viewports are actually on screen, not assume a constant. - [ ] **A scaled thumbnail/image widget for an in-transcript image.** (**P1**.) `SessionImage.kt`'s bitmap decode-and-downscale has no iris counterpart; iris's own image widget (used by `bench_images.rs`) draws a loaded texture but does nothing about sourcing or scaling one from a server-produced attachment. - [ ] **A modal/dialog primitive.** (**P1**, reused by **P3** and **P5**.) Needed for the session settings dialog, `UsageDialog`'s equivalent, and the delete-with-`deleteForeign` confirmation with its toggle switch. Build once, wherever it is first needed, rather than once per screen that wants one. - [ ] **A horizontal gauge/bar widget.** (**P1**.) For `SessionUsageBar`'s equivalent — a bounded fill reflecting a fraction, nothing fancier. - [ ] **A `BusyItem` equivalent: a dimmed row carrying an operation label that does not block its list's own scroll/drag.** (**P3**.) The Compose version tried an overlay first and it swallowed the drag along with the tap (AGENTS.md's "Shared appearance") — worth not repeating that attempt in iris before building the row-level version directly. - [ ] **A toggle switch.** (**P3**.) For the delete dialog's `deleteForeign` control; iris has no switch/checkbox widget yet as far as this pass found. ## Reconsider - [ ] **`WidgetView`.** Iris is unsure of it: what she wants is an easy way to compose a widget from others (a button is the main case). With sizing folded into `draw`, composing may be easy enough that `View` is redundant. Decide after the layout change lands, by writing a button both ways and keeping the one that is shorter to explain; delete the other rather than keeping two ways.