ai-app/RUST.md

Moving the app to Rust

Working document for the question Iris asked on 2026-09-04: what are the options for switching the phone app to Rust, ideally pure Rust with one UI framework shared with a future winit-based desktop application, at full feature parity and without giving up anything native, performance especially. Constraints she set: no Dioxus and nothing that draws through a WebView; no UI DSL (which rules out Makepad and Slint); the result should stay lightweight; platform-specific pieces are fine to maintain; reimplementing a framework piece from scratch where it does not fit is fine; effort and elapsed time do not matter, long-term robustness does; this clone is where things get tried before anything is committed to ai-app. Her own library, iris, is the in-house framework to be built up for this, with Masonry as the yardstick it is measured against.

Decisions get a date and a reason here, the way PLAN.md does. A section describes something that has been tried only where it says so, with a date.

Keep this file current as you work

This file is the handoff, and it is meant to let a session be cleared. Write each result into it as you get it, not at the end: the box ticked or the reason it could not be, the measurement with its number, the decision with its date and what it rejected, and anything that cost time to find out. Then a session that has filled its context can be cleared and the next one can pick up from this file alone, which is much cheaper than carrying a long conversation or re-deriving what was already measured.

Two things that follow. Write for somebody who was not here — name the command, the file and the number rather than "the fix" or "the earlier run". And write the failures and the dead ends too: "Venus is blocked by the emulator, not by Mesa" and "the present mode was not the cause" are worth as much as the successes, because they are what stops the next session spending an afternoon on them again.

Where things stand (2026-09-05)

• In flight, 2026-09-05 (session cleared mid-work, picked up again): E4 as a new iris/desktop-app crate on winit, embedding transcript-ui via build_tree beside a session list, with client-core::config holding the enrolment. The other half of this note, (a) the I5 touch-drag pan-vs-select gap as a DragArbiter in iris/src/sense.rs wired into transcript-ui's selection, is now done — see I5's own box below, "Gap closed, 2026-09-05". Design choices are summarised in DECISIONS.md at the repo root, which is the file Iris reads for choices made without her. Next after E4: I5's Android integration and the bench numbers.
• Done: E0 (toolchain), E1 (Masonry on android-view, which found the keyboard gap — now explained, see below), E2 (a transcript in Masonry, which found that Masonry has no touch-scroll on Android at all — see below), E3 (the Kotlin/Java shell over a JNI bridge into Rust, both pass conditions proved on the emulator — see its own box), E5 (the Gradle-free packaging xtask, both pass conditions proved — see its own box), I0a, I0b (iris builds on a pinned nightly and runs), I1 (parley + glyph atlas), I2 (iris on android-view), I3 (iris::widget::List), I4 (host half).
• E5 done, 2026-09-05. cargo xtask apk (new xtask/ crate at the repo root, zero dependencies) replaces Gradle for packaging app/shellApp: cargo ndk → javac/d8 → aapt2 → zipalign → apksigner, signed with the same key app/build-apk.sh uses. Both pass conditions held on this checkout's emulator: adb install -r over the Gradle-built shellApp succeeded (same key, so the signatures matched), and the notification service reached its follow-loop and posted a real notification while the app was backgrounded. E3's open kotlinc question resolved itself as a side effect of the one Gradle call still needed for AndroidX dependency resolution — see E5's own box for the full account, including the one disclosed place Gradle still runs and what was deliberately left undone (a real-device arm64-v8a install, dex shrinking).
• I5 — the transcript screen in iris: partial, 2026-09-05 (ticked [~] in its own box, not [x]). iris/transcript-ui/ builds a real transcript screen — markdown-folded rows in iris::widget::List, cross-row selection, a growing composer, tool-row expand-hold — on top of a new, genuinely useful iris capability this box added: SpanStyle, per-range text styling (core/src/primitive/text.rs), which is what lets one wrapped, selectable TextEdit carry a heading, bold, italic, inline code and a link all inside the same paragraph — exactly the inline-rich-text ceiling E2 found Masonry structurally unable to cross. Screenshotted via run-headless.sh (real inline styling visible, not just block-level). 9 new tests, all passing; cargo build/clippy/fmt/test --workspace and cargo ndk (both iris and transcript-ui) all clean. What did not happen this pass: any Android integration for this specific screen (no cdylib/Gradle shell exists for it yet, unlike tabs-ui's iris-android-app), and therefore the emulator-side pass condition (transcript-bench.sh against the Compose baseline, ui-trace tap-by-name on a row) — emu list showed the one emulator here held by another session, but the real blocker is that the integration work itself is unbuilt, not the emulator being busy. Full accounting, every citation, and the dated IRIS_TODO.md items are in I5's own box below. Update, 2026-09-05, same day: touch-drag panning over a row's own rendered text, which was not yet reachable for a specific, diagnosed reason (it competed with this box's own row-level drag-select for the same gesture, not an absent primitive), is now closed — a DragArbiter in iris/src/sense.rs, wired into transcript-ui's selection — see the box's "Gap closed" note. Android integration is the one item left before this box can tick [x].
• E3 done, 2026-09-05, and unlike E1/E2 it is committed to this repo (android-shell/ — a JNI-bridge crate on client-core — plus a new Gradle module app/shellApp/, left deliberately separate from app/androidApp so its ~13,000 lines of working Compose UI are untouched). Both pass conditions held: a notification arrived in Android's drawer while the app was closed, and a shared text share landed as a real userMessage in a sandbox session's transcript. Found and fixed three real bugs along the way — a generic JObject native parameter silently exporting the wrong JNI signature (UnsatisfiedLinkError), a class-by-name lookup failing from this crate's own background thread because a Rust-attached thread has no app ClassLoader (Error::NoClassDefFound, invisible without a logger installed), and onStartCommand opening two /notifications connections per enrollment — the last one a latent bug in Notifications.kt itself, found here rather than there. See E3's own box for the full account, the exact commands, and what was deliberately cut (attachment uploads, a session picker, the on-screen/banner suppression — all pending E4's screen).
• I4 — accessibility names via AccessKit: host half done and verified 2026-09-05, ticked in the box below. iris_core::ui::access::AccessTree builds one flat AccessKit tree from Widgets::named() (a side set only .label() populates, so an unnamed widget costs this nothing), pushed through accesskit_winit on the desktop and accesskit_android on Android, updated only when a name/role/bounds actually changes (a counter confirms it: 1 rebuild on first draw, 0 across an unchanged frame, 1 more after a real move). E1's detach-abort mitigation is carried (android/access.rs's raise_if_enabled). Every check that doesn't need the emulator is clean — see I4's own box for the exact numbers. What's left: the emulator itself is held by another session this pass, so ui-trace record --do "tap 'pad'" against iris-android-app's tabs screen (which now has five named buttons) has not been run for real yet — exact commands at the bottom of I4's box.
• E2 done, 2026-09-05, and its headline finding changes what "decide from the measurements" (recommendation item 3) can mean right now. Built a real transcript screen (~/src/android-view/e2-transcript, local, not committed — see E2's own box), fetching 854 real events from an app/ui-sandbox.sh session through client-core. Six of the seven "hard to get back" behaviours are answered with evidence either way; the seventh (measurable frames) is blocked before it can even start: neither of Masonry's scrolling widgets (VirtualScroll, Portal) reacts to a touch drag, only to a wheel-style PointerEvent::Scroll — confirmed by reading (virtual_scroll.rs:504-523, portal.rs:259-267) and empirically (a real swipe and a synthetic Android scroll event both moved nothing on screen). So transcript-bench.sh's own gesture cannot be performed against a Masonry transcript on Android today, which means the render-number half of E2's pass condition has no comparison to make yet — not a bad number, no number obtainable at all. Selection spanning rows and per-span rich text (bold/italic/inline code/links inside one paragraph) are also confirmed not possible on the pinned commit, each for a specific, cited reason. What did work: block-level rich text (heading size, monospace fences), real virtualisation of 854 rows, overwrite_anchor-based hold-top-edge on expand (screenshotted), and tap-by-name accessibility. Full writeup, every citation, and the exact repro commands are in E2's own box below.
• Done, 2026-09-04: the Widget::draw/layout redesign (LAYOUT.md). desired_width/desired_height/SizeCtx/Cache are gone; every widget in iris/src/widget/ implements one fn draw(&mut self, &mut Painter) -> Size. A moved widget (Scroll, Offset) now costs one move_offsets write resolved by a shared resolve_move WGSL function in both shader stages, independent of how many primitives are in its subtree — measured at 500 in iris/src/layout_tests.rs, which also covers the unchanged-frame, hit-test-after-move and mask-follows-move pass conditions as plain unit tests (no GPU or window needed, since UiRenderState touches neither). All four examples render pixel-identically to before the change. See LAYOUT.md's "Deviations found during implementation" for five real bugs the design's first draft did not anticipate — worth reading before touching Aligned, Sized, MaxSize, Scroll, or the move-slot lifecycle again. GpuTextures::grow_array (a second atlas layer opening) has now been exercised too, on tabs with PAGE temporarily lowered — see TEXTURES.md's "Exercised, 2026-09-04". Not done: a pixel-level screenshot check of a Masked-wrapped Scroll (no example builds one yet — the numeric check in layout_tests.rs stands in).
• E1's keyboard gap is Masonry's as_input_connection returning None (a TODO), not android-view or EditorInfo. android-view's own demo implements the InputConnection trait over a parley editor and gets real Gboard suggestions on this emulator — screenshotted 2026-09-04. android-view's accesskit_android adapter also has a reproducible abort (a client detaching, not attaching, is the trigger) — see E1 below for both, with the mitigation iris/I4 needs to carry.
• Resolved, 2026-09-04: iris's binding array does not survive real Android hardware. iris's texture pipeline used to ask every device, unconditionally, for VK_EXT_descriptor_indexing ("bindless" binding arrays), which a real share of Android hardware lacks. It has been rebuilt per TEXTURES.md's "Recommended shape": the glyph atlas is one texture_2d_array (a layer per page), a standalone image is its own ordinary Texture/BindGroup, and request_device now asks for no features and no binding-array limits at all. rigs/gpu-probe, rewritten to match, confirms request_device now succeeds on the emulator's software Vulkan (EMU_GPU=software, SwiftShader) — see TEXTURES.md's "Implemented, 2026-09-04" for the exact command and output, and for what was verified (rendering, via run-headless.sh) versus what was reasoned through but not separately stress-tested (a real second-atlas-page grow under load). Nothing here has been run on real Android hardware yet, only the emulator; the Android Vulkan Profile 2025 sourcing in "iris's binding array does not survive real Android hardware" below is what stands in for that until I2 gets a device.
• I2 — iris on android-view: done 2026-09-05. The android-view backend (iris/src/android/), the iris-android-app cdylib and Gradle shell, insets, the back gesture, and the full InputConnection bridge are all in and measured working — Gboard's suggestion strip reads real buffer content through it, the same bar E1 set. The render gap (nothing drew but the clear colour) is fixed: UiRenderNode::new seeded the GPU's window uniform from WindowUniform::default() (0, 0) rather than the surface's real size, so the vertex shader's / window.dim produced NaN/Inf clip positions on every primitive, on both Vulkan and GLES — winit's backend never hit this because winit fires an initial WindowEvent::Resized that corrects it before the first frame, and android-view has no equivalent event. Fixed by seeding the uniform from config.width/height at construction instead of depending on a later resize call. The tabs example now renders on the emulator on both backends (screenshotted); the GLES-only D2/D2Array warning was confirmed a red herring — still present post-fix, harmless. See I2's own entry below for the full writeup. E2 (a transcript in Masonry) is done — see its own box.
• I3 — iris::widget::List built and benchmarked 2026-09-05, ticked in the box below. Variable-height rows, virtualised, moved not relaid-out on scroll, insert-above-anchor and expand-hold both measured flat across N = 100/1,000/10,000. What is left is wiring it into an actual transcript screen and comparing against transcript-bench.sh's Compose baseline on the GPU emulator, which needs a session/scroll model around it (closer to I5's scope) — see I3's own box for the exact command once that screen exists. Read list.rs's module doc and IRIS.md's 2026-09-05 entry before touching it: a widget that fills whatever region it's offered (a Rect background) cannot be measured at a throwaway region and merely repositioned, a lesson that generalises beyond this one widget.
• client-core built (2026-09-04), item 1 of the recommendation: event-model/ (the event types, now shared with server/) and client-core/ (REST and SSE clients, transcript fold, cache, highlighter, ANSI parser, 85 ported tests). CLIENT_CORE.md maps Kotlin file to Rust module and lists what is not yet covered. ./run-tests.sh runs all three crates.
• The app itself is untouched. Everything so far is in iris/, in rigs/gpu-probe (a headless wgpu/Vulkan feature probe, pushable to a device with no APK — see the binding-array section), and in the other rigs; nothing under app/ or server/ has changed.
• Changed outside this repo, both in emulator-tools and both pushed: avd_serial now validates its cache by asking the device its AVD name rather than by checking the serial is still attached (a recycled port silently pointed this checkout at another session's emulator), and EMU_GPU=software was added as an opt-in that keeps a run off the host GPU and gives the guest a software Vulkan device. The default is unchanged, because -gpu host was measured and the Compose benchmarks depend on it.

What has to be reproduced

The app is ~19,000 lines of Kotlin. It splits three ways, and the split is what decides how much of a port is mechanical.

Pure logic with no Compose or Android in it, ~4,500 lines. Api.kt (1,142), Events.kt, EventStream.kt, Sse.kt, TranscriptCache.kt (589, touches java.io.File only), TranscriptSource.kt, MarkdownSyntax.kt, Languages.kt, Highlighter.kt, Ansi.kt, ResetCountdown.kt, Durations.kt, Sizes.kt, ModelName.kt, LoadState.kt, ImportableStream.kt. TranscriptUnits.kt and TranscriptItems.kt (the event fold into rows, ~940 lines) are logic with a handful of Compose annotations. This is also exactly the code that has JVM unit tests today. All of it ports directly, and most of it already has a Rust twin in server/: Events.kt is a hand-kept mirror of session/driver.rs's enum, the highlighter and the syntax scanner exist on the server for the explorer, and the cache compares the server's own JSON lines. Sharing these types between server and app is the single largest "keep things in sync" win available, and it does not depend on which UI framework wins.

Compose UI, ~13,000 lines. Screens, dialogs, the transcript list, the markdown renderer's customisations, tool cards, the file explorer viewer and editor. This is the part a UI framework choice is about.

Android platform code, ~1,500 lines, spread over 20 files. Every one of these is a Java-side object that no Rust framework can replace, because Android only offers them as Java classes:

• NotificationService — a foreground service holding the /notifications SSE stream while the app is closed, with its ongoing notification, specialUse type and the POST_NOTIFICATIONS request.
• MainActivity — edge-to-edge, the ACCESS_LOCAL_NETWORK runtime permission (Android 17), singleTop intent routing for aiapp://enroll, notification taps, and the share sheet (ACTION_SEND, any MIME type).
• ServerConfig — the bearer token sealed under an Android Keystore AES-GCM key, shared with Dev Updater through wg-app-link's :link.
• EnrollmentScanActivity — the in-app QR scanner (zxing, camera).
• Attachments — ContentResolver reads of shared URIs, BitmapFactory decode and downscale, EXIF orientation.
• SessionImage — bitmap decode for produced images.
• ScrollAnchor, Drafts — SharedPreferences; CrashLog — filesDir.
• TranscriptCache — cacheDir.
• DebugStats/FrameStats — Choreographer frame timing and the render report; runtime-tracing names composables in a system trace.

So "pure Rust" on Android means Rust owns every line of logic and drawing, behind a thin shell of Java stubs, and a packaging step that produces a signed APK. How thin, and whether Gradle is inevitable, are answered below.

How much Java is unavoidable, and why

Rust can call any Android API through JNI (jni crate, with ndk-context handing over the JavaVM and the Activity): posting a notification, startForegroundService, the Keystore, ContentResolver reads, permission requests, WindowInsets, the clipboard. None of that needs a line of Kotlin. What JNI cannot do is define a class that the system instantiates by name from the manifest — an Activity, a Service, an Application, a BroadcastReceiver. Those must exist as dex bytecode inside the APK before any Rust runs, because the framework constructs them and only then calls into native code. NativeActivity is the platform's own stub for the Activity case; there is no NativeService, and android-view ships its own View subclass for the same reason.

So the floor is roughly two Java classes of ten lines each: an Activity and a Service whose lifecycle methods are declared native and registered from JNI_OnLoad, plus whatever android-view already provides. Everything they would have done in Kotlin — insets, intent routing, the SSE follow loop, the notification builder — is Rust reached through those stubs. Writing the stubs in Java rather than Kotlin drops kotlinc from the toolchain; javac comes with the JDK Gradle already needs. Generating the dex from Rust is not worth it: there is no mature Rust dex writer, and the stubs never change.

Can the APK be built without Gradle?

Yes. An APK is a zip containing a binary-XML AndroidManifest.xml, resources.arsc, classes.dex, lib/<abi>/*.so and assets, aligned and signed with the v2 scheme. The tools are aapt2 (manifest and resources), d8 (Java bytecode to dex), zipalign and apksigner, all in the SDK's build-tools, none of them Gradle. Three ways to drive them:

• A cargo xtask (or build.rs-adjacent script) that runs cargo ndk for each ABI, javac + d8 for the stubs, aapt2 link, zipalign, apksigner. About 150 lines, every step visible, no AGP, no Gradle daemon holding 2.8 GB between builds. The pinned-CA constant becomes a build.rs reading the same certs/ca.pem path.
• cargo-apk2: the maintained successor to cargo-apk, and unlike it compiles java_sources / kotlin_sources into the dex and declares multiple activities and services with intent filters from [package.metadata.android], with per-profile keystores and optional aapt2. Exactly the shape needed; the question is whether a third-party tool with one maintainer beats 150 lines we own.
• cargo-apk / xbuild: unmaintained and NativeActivity-only. No.

What Gradle would take with it: Android Lint (which found two real bugs here, but in Kotlin that would no longer exist — with forty lines of Java stubs there is little left for it to find), manifest merging, R8, and the generated-source plumbing. What it gives back: one toolchain, cargo end to end, and Dev Updater keeps calling build-apk.sh exactly as now. Recommendation: the xtask, with cargo-apk2 read for the details it already got right (v2 signing, uses-feature, ABI splits).

The behaviours that are hard to get back

Reading the Compose code for what a replacement must be able to express, rather than what it happens to look like:

1. The transcript is one selectable body of text. One SelectionContainer around the whole lazy list, so a selection runs from a reply into the tool output beneath it. The framework needs selectable read-only rich text across many rows, with the platform's selection handles and clipboard on the phone.
2. Rich inline text: markdown with links (one tap detector per text, not a node per link), inline code chips drawn behind the text, tables with wrapping cells and a sideways scroll, syntax-highlighted fences, ANSI colour in tool output, Nerd Font icon glyphs. Needs a text layout engine with spans, not just styled labels.
3. A bottom-anchored virtualised list of variable-height rows, paged in both directions (800-event pages, HISTORY_SCREENS measured in viewports), with a saved scroll anchor per session, "hold the edge nearest the tap" when a row expands (holdTopEdge, done in the layout pass so the wrong frame is never drawn), and rows keyed so that a run of tool calls stays one row while it grows.
4. The soft keyboard: the composer resizes with the IME, the guard against a stuck inset animation, drafts per session, autocorrect and suggestions from the phone's own keyboard. This is where most Rust frameworks fail on Android today; see below.
5. Platform integration through the app model: foreground service, notifications, share sheet, deep link, Keystore, camera, back gesture, edge-to-edge insets, local-network permission.
6. Accessibility names on icon buttons, which the bench scripts depend on (ui-trace taps by label). A framework with no accessibility tree also breaks the measuring rig.
7. Measurable frames: the debug render report, and a way to attribute a frame's cost to a widget on the real phone.

The two constraints that decide it

1. Android text input. Every framework built on winit inherits winit's Android backend, and that backend cannot drive the soft keyboard properly: the IME tracking issues (#1823, #2766) are open, ReceivedCharacter is unimplemented on Android (#2305), and the android-activity groundwork for editor actions only merged in February 2026 (PR #214) with the winit half still to come. Composition, autocorrect and suggestions need an InputConnection implemented on the Java side, which winit's NativeActivity/GameActivity model does not offer. The frameworks that type on Android today each wrote their own Java glue (Slint, Makepad), and the one designed to do it the way Android intends is android-view: a Rust implementation of an Android View, with text input through InputConnection, accessibility, touch, callbacks on the UI thread, usable either as a whole app or embedded beside ordinary Android components. It is marked WIP. Both Linebender (its Masonry demo lives in that repo) and Robius/Makepad (Robrix's release notes say Android lacks a "full" keyboard and they are integrating android-view for it) are converging on it. That makes android-view the phone-side foundation whichever widget set sits on top, and the first thing to build and measure here.

2. Rich, selectable text and a virtualised list. Frameworks group by their text stack:

• Parley + Fontique + Vello (Linebender): rich spans, selection and editing utilities, IME support driven through ui-events, AccessKit text properties (Linebender 2026 Q1, parley). Used by Masonry/Xilem, and by Blitz. Vello proper needs compute shaders; vello_hybrid (CPU path processing, GPU compositing) is "roughly beta" and runs on GLES too, and Vello CPU exists as a no-GPU fallback.
• cosmic-text (iced, egui optionally): good layout, but the widgets on top decide selection. iced's markdown widget is not selectable (discourse).
• Slint's own: TextInput with read-only is the selectable-text trick; there is no inline rich text at all (issue #1325, markdown request #6684 both open). A markdown transcript with links and code chips cannot be drawn.
• Makepad's own: GPU/SDF text, a Markdown widget and a virtualised PortalList in makepad-widgets.

Options

A. Keep Compose, move the logic into a Rust core (uniffi)

A client-core crate (events shared with the server, API client, SSE, transcript fold, cache, markdown model, highlighter, ANSI) exposed to Kotlin through uniffi. Compose keeps drawing. Desktop would be a second UI (iced or Compose Desktop) over the same core.

• For: the logic and the wire types stop drifting from the server today, with tests in one language. Incremental and always shippable.
• Against: it is not what was asked for. The 13,000 lines of UI stay Kotlin, the desktop app shares no UI code, and the :link Kotlin module stays. uniffi's Kotlin Multiplatform bindings are a community fork; the Android-only bindings are Mozilla's and solid.
• Verdict: not the destination, but step one of every other option is building this crate, so it costs nothing to keep it as the fallback.

B. Slint

Rust on Android is officially supported (minSdk 26, android-activity backend, own Java IME glue, safe areas and keyboard insets since 1.15, Skia renderer needs clang). Royalty-free licence requires disclosing Slint use; GPLv3 otherwise. UI is a separate .slint DSL, not Rust.

• Against: no rich inline text (see above), so the transcript cannot be drawn as it is today; the UI language is not Rust, which forfeits the "compiler catches it" motivation for the half of the code that is UI.
• Verdict: rejected on rich text alone.

C. iced

Elm-style, Rust-only widgets, desktop-first, winit + wgpu. Has a markdown widget and rich_text with links. The maintainer states mobile is a non-goal (iced); a community Android example exists and its author could not get the soft keyboard working, patched widgets for touch, and notes no accessibility (HN thread). Markdown is not selectable; scrollable is not virtualised.

• Verdict: a fine desktop toolkit and the one Iris named, but every phone-side gap (IME, touch, accessibility, selection, virtualisation) would be ours to build and maintain against a project that does not want them. Not the shared framework.

D. egui

Immediate mode, winit-based on Android, AccessKit integration, selectable labels across a Ui. Repaints only on input by default, so battery is not the immediate-mode worry. Android IME is blocked on winit (discussion); the workaround is an in-app virtual keyboard, which is exactly the non-native keyboard to avoid. Variable-height virtualised lists are manual (show_rows assumes uniform heights). Looks like egui, not Material.

• Verdict: workable on desktop, wrong on the phone for the same reason as iced, plus a look that would need a full custom style.

E. Makepad

GPU-rendered, hybrid retained/immediate, live_design! DSL with hot reload, MIT, 1.0 in 2025 (makepad). Ships Android apps today with its own Java glue; Robrix (a Matrix chat client, the closest analogue to this app) is its reference application on Android, iOS and desktop. Has Markdown, PortalList (virtualised), TextInput. Robrix reports the Android keyboard is not "full" and is moving to android-view for it; the README says non-standard targets "may require minor fixes".

• For: the only option that already ships a chat-shaped app on Android and desktop from one codebase, with the widgets this app needs.
• Against: the DSL is its own language with its own shader-based styling, so a large part of the UI would not be checked by rustc; the rendering model (SDF everything) is a different world from Compose's, and selection across a Markdown widget is unverified.
• Verdict: rejected 2026-09-04 — Iris does not want a DSL. Kept here so its Android keyboard status stays a data point about android-view, not as an option.

F. Masonry / Xilem on android-view (Linebender)

Retained widget tree (Masonry) with a reactive view layer (Xilem) that reads like Compose; Rust all the way down; Vello, Parley, Fontique, AccessKit, ui-events. Widgets include Prose (selectable read-only rich text), TextArea, VirtualScroll, and this year Svg, Split, CollapsePanel, a new layout system, and IME through ui-events independent of winit. masonry_android_view exists in the android-view repo and is "not yet generally usable"; Xilem calls itself experimental. Desktop runs on winit. Vello needs a compute-capable GPU or falls back to vello_hybrid/CPU.

• For: the only stack where every hard behaviour above maps onto a component designed for it: selection and rich text (Parley/Prose), virtualised variable heights (VirtualScroll), native IME (android-view's InputConnection), accessibility (AccessKit, now with an Android crate), one Rust widget language on both platforms. The team is the one writing the Android integration everyone else is adopting.
• Against: pre-1.0 with API churn each release; a small team; no Material widget set, so every control's look is ours; some of the pieces (masonry_android_view, vello_hybrid) are explicitly unfinished. Being early means fixing things upstream ourselves, which Iris said is acceptable.
• Verdict: the option to try first, because it is the only one whose gaps are "not finished yet" rather than "not designed for this".

G. iris — the in-house library, and what "from scratch" means here

cat16/iris, read 2026-09-04 from the one public commit (2026-01-31, "portfolio copy"; ~8,700 lines in core, macro and the crate itself). Retained-mode widgets stored outside the render tree, wgpu 28 directly, winit 0.30, cosmic-text 0.16 (parley since I1), a relative-anchor-plus-offset layout with rest() and rel() lengths, a postfix builder API (rect(..).radius(30).on(CursorSense::click(), ..) .sized(..).align(..)), events handled where the widget is declared, and a single-threaded context passed explicitly — all of which reads like this codebase's own rules. There is text editing (widget/text/edit.rs), images, masks, spans and stacks; the TODO names text resizing as per-frame slow and scaling as unsolved. It requires nightly (fourteen #![feature] gates as vendored, among them const_trait_impl, unboxed_closures, portable_simd, associated_type_defaults; eleven after I0b and I1 — see those steps for the current list). Desktop only; no Android surface, no IME, no accessibility tree, no virtualised list, no rich-text selection.

That list is the work, and some of it is done. As of 2026-09-04 it builds on a pinned nightly, runs on this machine's GPU, has parley and a glyph atlas, and iris-core cross-compiles to Android. What it still lacks from the list above is the Android surface, the IME bridge, the accessibility tree and the virtualised list — I2, I3 and I4.

iris is not a candidate to be tested as it stands. It is the in-house library (Iris, 2026-09-04): "essentially a good start to a rewrite from scratch", to be maintained and extended by the sessions working here. So the list above of what it lacks is a work list, not a score. When the app needs something iris does not have, the answer is to build it into iris. The layer iris has is the widget and layout layer; the layers it needs are the same ones Masonry gets from android-view, Parley and AccessKit, and there is no reason iris cannot sit on those same foundations rather than reinvent them — the surface, the keyboard bridge and the accessibility tree are platform plumbing, not a framework's identity. The text stack was the first real design decision in that work, and it is settled: Parley, with a glyph atlas (I1, 2026-09-04).

Two things to carry into that work honestly. Nightly is the opposite of "holds up long term": a build that breaks on a toolchain update, on the machine Dev Updater builds on, unattended. Done in I0b — iris/rust-toolchain.toml pins nightly-2026-09-03 — and the gate list lives with I0b and I1, to be retired as they stabilise or are designed around; it is down from fourteen to eleven. And a one-person framework carries every gap itself, which is what Iris said she is willing to do.

"From scratch" therefore means iris, not a fourth thing. Masonry stays in the plan as the yardstick and the fallback: building its demo and its version of the transcript screen first says what a finished stack costs on this hardware, proves android-view before iris depends on it, and gives a comparison that is measured rather than remembered.

Not considered further: GPUI (Zed) mobile is a community fork that depends on unpublished crates; Dioxus/Blitz is excluded by Iris (its native renderer is Parley/Vello under HTML semantics, and the earlier tdep-survey/app-dioxus spike parked it on a vello_hybrid stroke bug and shipped the WebView); Compose Multiplatform Desktop would give a desktop app for nothing but in Kotlin, which is the opposite direction.

Weight and debug builds

Iris remembers the Linebender stack being slow in debug. What is behind that is the dependency graph — Vello, wgpu, Parley, Fontique, Skrifa — running unoptimised on the CPU side (path encoding, shaping), not the widget layer. Xilem's own advice is only split-debuginfo = "unpacked" to keep target/ small; the fix everyone with this shape of dependency tree uses is to optimise dependencies while leaving the app crate at opt-level = 0:

[profile.dev.package."*"]
opt-level = 2

Measured 2026-09-04, and it is not the widget layer. iris's own graph (wgpu + winit + cosmic-text at the time) built cold in 43s with a 2.1 GB target/, and 1m46s with a 1.5 GB target/ under the profile above — so the knob costs build time and saves disk here, and plain debug was never the problem. Masonry's graph is the one with Vello, Parley, Fontique and Skrifa in it, and E1 gives the number that matters for it: libmain.so is 181 MB in debug and 11 MB in release. That size is also a correctness issue rather than only a weight one — a debug build labels its Vulkan objects, and the emulator's driver segfaults in SetDebugUtilsObjectNameEXT when it does. Runtime cost of the profile knob is still unmeasured; resident memory and the frame cost of an 800-event page want E2. Vello proper needs compute shaders and carries a large shader set; vello_hybrid is lighter and Masonry can now render through either (or Vello CPU) via its imaging abstraction, so "keep it light" has a knob inside the same stack.

Recommendation

1. Build client-core now, whatever the framework (done 2026-09-04, see CLIENT_CORE.md). A Rust crate holding the event model (shared with server/ as one crate, ending the Events.kt mirror), the API and SSE clients, the transcript fold, the cache, the markdown block model, the highlighter and the ANSI parser, with the existing JVM tests ported. It is the part of the app that is already tested, already logic, and already duplicated on the server.

2. One foundation, two widget layers. The platform plumbing is shared whichever way the decision goes: android-view for the Android surface, keyboard and accessibility bridge; wgpu for the GPU; AccessKit for names; winit on the desktop. On top of it, Masonry as the yardstick (E1, E2) and iris as the thing being built (I0–I5), both aimed at the same transcript screen with the same pass conditions.

3. Decide when the transcript screen exists in both, from the measurements, and record the decision here with the numbers. If iris carries the screen within the Compose baseline, it is the app's framework and Masonry was the calibration. If it does not, the measurement says which parts of Masonry to adopt underneath it.

   Not decidable yet, 2026-09-05 — what's missing, named rather than guessed at. Neither side of this comparison has a render number: E2 found Masonry's own scroll gesture path absent on Android entirely (its box, "measurable frames"), and I5 built the iris side of the screen (iris/transcript-ui/) but not the Android integration around it — no cdylib/Gradle shell exists for this screen yet (unlike tabs-ui's iris-android-app, I2), so there is nothing installed on a device for transcript-bench.sh to measure against the Compose baseline. What would close this: build that integration (real client-core networking against app/ui-sandbox.sh --delay, a cdylib

   • Gradle module the way I2 did for tabs-ui), then run transcript-bench.sh's gesture on both. Until then, the decision rests on the structural findings both sides did produce: Masonry cannot do cross-row selection or per-span inline rich text at all today (E2's grep -rln, zero hits, cited in its own box), and iris now does both (I5's SpanStyle and selection.rs) as well as programmatic touch-scroll (I3) — three structural points in iris's favour with no opposing measurement yet on either side.

4. Then the shell (E3), the desktop window (E4) and the packaging (E5), which do not depend on the choice.

Experiments, in order

Each has a pass condition that is a measurement in this clone. The rig matters: this emulator runs -gpu host with host Vulkan switched off (GPU_HOST_FEATURES in emulator-tools, a gfxstream/Venus gap), so inside the guest a wgpu app gets GLES, not Vulkan; the earlier Dioxus spike also needed WGPU_GLES_MINOR_VERSION=1 for compute shaders and found wgpu's Android backend wants API 26 (a libc symbol). The real phone has Vulkan. Per the standing rule, a rig limit is something to fix before it is accepted.

• E0 — toolchain (done 2026-09-04). Installed under the user-owned SDK: NDK r29 (29.0.14206865), 2.4 GB at ~/Android/Sdk/ndk/29.0.14206865, the newest stable — r30 is still at rc.3. cargo-ndk 4.1.2. Verified by cross-compiling a scratch cdylib to both ABIs: file reports "for Android 26, built by NDK r29 (14206865)" for aarch64-linux-android and x86_64-linux-android. Two things to know at the call site. cargo-ndk 4's API-level flag is -P, not -p — -p is now passed through to cargo as --package, so the old cargo ndk -t arm64-v8a -p 26 panics with unknown package: 26 and dumps the whole environment to stdout as a bug report, which is worth not doing in a log somebody might paste. And the Android targets were installed for stable only; the pinned nightly needs its own, which iris/rust-toolchain.toml now declares.

• E1 — android-view's Masonry demo on this emulator (2026-09-04). It builds, renders on the GPU through Vulkan, exposes its accessibility tree, and the phone's own keyboard types into its editor — but with no autocorrect and no suggestions. Ticked because everything it was meant to establish is established, including the one gap; that gap is now E2's problem and I2's.

  *Build.* `~/src/android-view` at `bec6c62`, x86_64 rather than the
  README's arm64 because that is what this emulator is:
  `cargo ndk -t x86_64 -P 26 -o masonry-app/src/main/jniLibs/ build -p
  android-view-masonry-demo --release`, then
  `./gradlew :masonry-app:assembleDebug`. **`libmain.so` is 181 MB in
  debug and 11 MB in release** — the loudest single number about
  Vello's dependency graph, and the reason the release build matters
  for more than speed.
  
  *Renderer.* wgpu takes **Vulkan**, and the emulator log confirms it
  from the other side: `Created VkDevice ... for application:'wgpu'`.
  Two things were needed. The emulator must be given Vulkan at all —
  `-feature Vulkan` with `VK_DRIVER_FILES` pointing at the SDK's
  `vk_swiftshader_icd.json`, **plus `-no-snapshot-load`**, which is the
  piece this file had flagged as untested: without a cold boot the
  guest keeps the snapshot's old GPU config and `cmd gpu vkjson`
  reports zero devices however the host is configured. And the native
  library must be **release**: a debug build calls
  `SetDebugUtilsObjectNameEXT` to label its image views, and the
  emulator's own guest driver (`vulkan.ranchu.so`) segfaults inside it.
  On GLES, with no Vulkan available, it instead fails
  `Surface::configure` with "Invalid surface" — untriaged, since the
  Vulkan path works and Vello wants compute shaders anyway.
  
  *Accessibility works*, which E2's condition 6 and every bench script
  depend on. `ui-trace` reads Masonry's AccessKit tree: "Add task"
  arrives as a named `Button`, the editor as an `EditText` node. So
  tap-by-name works against a Masonry screen for any control carrying
  a name; the demo's editor carries none, which is the demo's omission
  rather than the framework's.
  
  *The keyboard: real input yes, suggestions no.* Tapping the editor
  opens the actual soft keyboard (`mInputShown=true`, Gboard), and
  tapping its keys types into Masonry — "teh" typed key by key, with a
  caret. What does **not** appear is Gboard's suggestion strip. The
  control is what makes that a finding rather than an impression: the
  **same three key taps in the Settings app's search field, on the same
  device in the same session, produce "teh | the | yeh"**. So the strip
  works here and android-view's editor is not asking for it — most
  likely the `EditorInfo` its `InputConnection` reports. That matches
  Robrix's report that the Android keyboard is not yet "full", and it
  is the single most important thing to fix or fund upstream, because
  composition, autocorrect and suggestions are exactly what the
  composer in this app needs and exactly what `winit` cannot do at all.
  
  **Cause found 2026-09-04, and it is Masonry's, not android-view's.**
  `~/src/android-view/masonry/src/lib.rs:531` is
  
      fn as_input_connection(&mut self) -> Option<&mut dyn InputConnection> {
          // TODO
          None
      }
  
  so the Masonry demo has **no `InputConnection` at all**; `RustView`
  returns null from `onCreateInputConnection` and the IME falls back to
  dispatching raw key events, which is exactly the behaviour observed —
  keys arrive, composition does not exist, so there is nothing for
  Gboard to suggest against. It is not a wrong `EditorInfo`, and the
  guess above that it was is withdrawn.
  
  android-view's **own** demo (`demo/src/lib.rs`, packaged by `app/`)
  implements the whole trait against a parley editor and asks for
  `INPUT_TYPE_CLASS_TEXT | CAP_SENTENCES | AUTO_CORRECT | MULTI_LINE`
  with `IME_FLAG_NO_FULLSCREEN | NO_EXTRACT_UI | NO_ENTER_ACTION`
  (`demo/src/lib.rs:588`). So the capability is present in the layer
  iris would sit on, and the 30-odd method `InputConnection` trait in
  `src/ime.rs` — `set_composing_text`, `set_composing_region`,
  `finish_composing_text`, `text_before_cursor`, `cursor_caps_mode`,
  `request_cursor_updates`, and `InputMethodManager::update_selection`
  to push the selection back — is the full surface an IME needs.
  **This changes what I2 costs**: the IME bridge is a trait to
  implement over iris's parley editor, not a gap to fund upstream. It
  also means E2 inherits Masonry's TODO, so a Masonry transcript will
  have the same dead composer until somebody fills that in.
  
  **Measured on the emulator, same session, same device.** Built
  android-view's own demo — `cargo ndk -t x86_64 -P 26 -o
  app/src/main/jniLibs/ build -p android-view-demo --release`, then
  `./gradlew :app:assembleDebug`, installed with `ANDROID_SERIAL=$(emu
  serial)` — and tapped into its editor. `dumpsys input_method` reports
  `mInputShown=true` with `mServedView=…viewdemo.DemoView`, and the
  screenshot shows **Gboard's suggestion strip populated with "dolor |
  Dolores | door"**: the caret had landed inside the word *dolor* in
  the demo's lorem ipsum, and Gboard read that word out of the Rust
  editor through `text_before_cursor`. So on this emulator, through
  android-view, a parley editor gets a real IME with real suggestions
  drawn from its own buffer. That is the bar E1 could not reach and the
  bar I2 is written against, and it is now known to be reachable.
  
  *One crash seen once — reproduced and diagnosed 2026-09-04.* With an
  accessibility client attached the app aborted, stack:
  `android_view::view::do_frame` → `CallbackCtx::finish` →
  `accesskit_android::event::QueuedEvents::raise` →
  `send_completed_event` → `unwrap()` on `Err(JavaException)`.
  android-view builds `panic = "abort"`, so a JNI call that throws
  takes the process. Two later `ui-trace record` runs left the app
  alive, so the trigger looked narrower than "a client is attached".
  
  **It is the opposite of "a client is attached": it is a client
  having *detached*.** `accesskit_android`'s `State` enum
  (`adapter.rs:161` in 0.4.0, `:192` in 0.8.0) is
  `Inactive | Placeholder | Active`, and **nothing ever moves it back
  to `Inactive`**. A client — `ui-trace`, which is uiautomator — calls
  into the node provider once, `get_or_init_tree` promotes the adapter
  to `Active`, and it stays there for the life of the process. Every
  later change then returns `Some(QueuedEvents)`, `raise` calls
  `ViewParent.requestSendAccessibilityEvent`, and that reaches
  `AccessibilityManager.sendAccessibilityEvent`, which on the main
  looper **throws `IllegalStateException("Accessibility off. Did you
  forget to check that?")` when accessibility is disabled**. jni-rs
  returns `Err(JavaException)`, `send_completed_event` unwraps it, and
  `panic = "abort"` ends the process.
  
  *The controlled run*, one process (pid 4085), `settings get secure
  accessibility_enabled` = 0 throughout:
  
  - tapped the editor and typed three keys with `adb shell input tap`,
    no client ever attached — **alive**;
  - one `ui-trace record -d 800` with no gesture at all, then two
    seconds' wait — **still alive** (the queue was raised while the
    client was still there);
  - the very next three keystrokes, same process — **aborted**, same
    stack.
  
  So the failure is not the recording; it is the **first thing that
  changes the accessibility tree after a recording ends**. That makes
  it a standing hazard for this project rather than an oddity:
  `transcript-bench.sh`, `stream-bench.sh` and `bench-lib.sh`'s
  tap-by-name all attach and detach uiautomator, so on a Rust app the
  typing or scrolling *after* a bench run is what dies, several
  seconds away from anything that looks like a cause.
  
  **Still present at head**: 0.8.0 is the newest `accesskit_android`
  (the demo resolves 0.4.0) and both the unconditional `unwrap` in
  `send_completed_event` and the one-way `State` are unchanged there,
  so upgrading is not the fix. **Our mitigation for I2/I4 is a gate we
  own**: ask `AccessibilityManager.isEnabled()` before calling
  `raise`, and drop the events when it says no. Worth reporting
  upstream as well — the honest fix is for `raise` to clear a pending
  exception rather than unwrap it, since a view can be detached or
  accessibility switched off between queueing and raising no matter
  who is calling.
  
  *A rig trap that cost a wrong conclusion.* Several bounded runs were
  given `sleep N; emu down` watchdogs, and one armed for an earlier
  experiment fired in the middle of a later one — the app vanished, adb
  hung, and it read exactly like the Vulkan path crashing. It was not.
  A watchdog must be scoped to the process it guards (`kill $pid`, with
  the pid captured at launch) rather than to whatever AVD is running
  when it wakes, and only one should be armed at a time.
  

• E2 — a transcript in Masonry (2026-09-05). Built and run on this emulator. It found the thing it was measuring for: a framework-wide gap that blocks the bench comparison itself, plus a full accounting of the seven behaviours. Ticked on E1's own precedent -- "everything it was meant to establish is established, including the one gap."

  *Where it lives.* `~/src/android-view/e2-transcript` (new workspace
  member, `crate-type = ["cdylib"]`, `lib.name = "main"`), packaged by
  a new Gradle module `~/src/android-view/e2-app` copied from
  `masonry-app` (`E2View`/`E2Activity`, package
  `org.linebender.android.e2transcript`). Neither is committed to
  `ai-app-2` or pushed anywhere -- same as E1, this is a local
  experiment against the `xilem` commit
  `e14ba3a5f9461b403cb30d95826187fba7f6924b` and the `android-view`
  commit `bec6c62a96cef8239b0fd7fedeef9b184d02e3a1`, reproducible from
  the commands below rather than from a remote.
  
  *Build.* Depends on `client-core`/`event-model` from this checkout by
  path (`../../../repos/ai-app-2/client-core`) -- real code, not a
  reimplementation: `ApiClient`/`UreqTransport` for the HTTP fetch,
  `fold_event`/`group_tool_runs` for the transcript fold, exactly what
  the app itself would use. The sandbox CA and a session's URL/token
  are baked in at build time via `env!()`/`include_bytes!()`, the same
  pattern the real APK uses to pin its CA (AGENTS.md), since this is a
  throwaway screen with no enrollment flow:
  
      cd app && ./ui-sandbox.sh start   # prints the port and token
      sid=$(./ui-sandbox.sh spawn e2test)
      ./ui-sandbox.sh send "$sid" @/tmp/big.md   # markdown content
      ./ui-sandbox.sh send "$sid" "/tools 3"     # a grouped tool run
      cd ~/src/android-view
      E2_SANDBOX_URL=https://10.0.2.2:<port> \
      E2_SANDBOX_TOKEN=<token> \
      E2_SANDBOX_SESSION=<sid> \
      E2_CA_PEM_PATH=$HOME/.config/ai-app/certs/ca.pem \
          cargo ndk -t x86_64 -P 26 -o e2-app/src/main/jniLibs/ \
              build -p e2-transcript --release
      ANDROID_HOME=~/Android/Sdk ./gradlew :e2-app:assembleDebug
  
  **`libmain.so` is 13.5 MB release** (E1's masonry-demo was 11 MB;
  the difference is `client-core`'s `ureq`/`rustls` stack, which E1's
  demo does not link). Release native lib, debug Gradle variant --
  the combination E1 found necessary (a debug build's
  `SetDebugUtilsObjectNameEXT` segfaults this emulator's Vulkan
  driver).
  
  *Emulator.* This checkout's own AVD (`ai-app-2`, not `ai-app`, which
  another session already had up), booted with Vulkan the way E1
  established: `GPU_HOST_FEATURES="-feature Vulkan"
  VK_DRIVER_FILES=$HOME/Android/Sdk/emulator/lib64/vulkan/vk_swiftshader_icd.json
  emu up`. `adb shell cmd gpu vkjson` confirmed a device before
  anything was installed. Torn down with `emu down` at the end of this
  session (see "Where things stand" below for the exact state left).
  
  *What it does.* `fetch_rows()` (`e2-transcript/src/lib.rs`) makes one
  blocking `fetch_transcript_page(session, None, 800, false)` call
  before the widget tree exists, folds every line through
  `client-core`, and groups tool runs -- 854 real events from a mixed
  sandbox session (markdown paragraphs/headings/fences plus a
  three-call tool run from the echo driver's `/tools 3`). Each
  `TranscriptRow` becomes one `VirtualScroll<dyn Widget>` child,
  built lazily from `VirtualScrollAction` the way
  `masonry_winit/examples/virtual_fizzbuzz.rs` does it. **This is a
  deliberate scope cut from "page 800 events" as live paging**: all
  854 rows' content is fetched once, and what `VirtualScroll` pages is
  *widget construction*, not a second round of network calls per
  scroll -- wiring a background-thread fetch woken across the JNI
  boundary (the way I2's `ssh.rs` attach-and-call works) is real work
  this experiment did not need to answer its question. `markdown.rs`
  is a `pulldown-cmark` event-stream walk into a small `Block` enum
  (`Text`/`Heading`/`Code`), with its own module doc explaining the
  one real ceiling it hit (below).
  
  *Verification.* `cargo fmt -p e2-transcript -- --check` clean.
  `cargo ndk -t x86_64 -P 26 clippy -p e2-transcript --all-targets`:
  **zero warnings in this crate** (the only clippy output at all is
  from `android-view` itself, a vendored dependency this experiment
  does not own). `cargo ndk -t x86_64 -P 26 test -p e2-transcript
  --lib` (run against the emulator, since the crate is
  `cfg`-unconditionally Android): 1 test, `markdown::parse`'s block
  split, passing. No larger test surface exists to port -- this is a
  throwaway screen, not a library, matching AGENTS.md's "match the
  codebase's testing posture."
  
  *Screenshots* (all `/tmp`, not committed -- see the standing rule
  against transcripts leaving this repo, which applies equally to a
  screenshot of one): `e2-screenshot2.png` first real content;
  `e2-expand.png` a tool row expanded with its top edge held;
  `e2-markdown.png` a heading/bold/italic/inline-code/link/fenced-code
  message (the "You said: ## A Heading" line is the sandbox's echo
  driver prefixing the literal input text before the `##`, which
  keeps `pulldown-cmark` from recognising it as a heading -- a fixture
  artifact, not a finding about Masonry).
  
  **The seven behaviours, each shown or given a sourced reason:**
  
  1. **One selectable body of text spanning rows -- not possible, and
     it is a real ceiling, not an oversight.** `Prose` wraps exactly
     one `TextArea<false>`, which wraps exactly one
     `parley::PlainEditor` (`masonry/src/widgets/prose.rs`: "Note that
     copying is not yet implemented"). Selection lives entirely inside
     that one editor: `TextArea::on_pointer_event`
     (`masonry/src/widgets/text_area.rs:414-459` in the pinned `xilem`
     commit) captures the pointer on `Down`
     (`ctx.capture_pointer()`) and drives `self.editor`'s own
     `extend_selection_to_point` on `Move` -- there is no code path,
     in `masonry_core` or `masonry`, that extends a selection into a
     second widget's editor. A drag that starts in one row's `Prose`
     and continues into the next is still that first row's own
     `PlainEditor` being asked for a point outside its bounds; it
     cannot reach the second row's text. Confirmed by reading, not
     guessed at: there is no `SelectionContainer`-shaped type
     anywhere in `masonry`, `masonry_core` or `xilem` (checked with
     `grep -rln "SelectionContainer\|cross.widget.*selection"`, zero
     hits).
  2. **Rich inline text -- block-level yes, inline no, and both for
     the same reason.** `TextArea::edit_styles()` returns one
     `&mut StyleSet<T>` for the whole editor
     (`masonry_core/src/core/text.rs:29-32` defines `StyleSet` as
     `parley::StyleSet<BrushIndex>`, applied editor-wide); the type's
     own comments say why nothing finer exists yet:
     `// TODO: RichTextInput 👀` and
     `// TODO: Support for links - https://github.com/linebender/xilem/issues/360`
     at `masonry/src/widgets/text_area.rs:43-44`. So bold, italic,
     inline code and a link *inside one paragraph* cannot each carry
     their own style without leaving `TextArea` for a hand-rolled
     `parley::Layout` (which loses selection, the caret and copy,
     since those live inside `PlainEditor` specifically). What **is**
     real: each markdown block is its own `Prose`, so a heading is a
     bigger font and a fenced code block is monospace, screenshotted
     in `e2-markdown.png` -- block-level style works because it is
     block-level *widgets*, not a rich-text API. Tables and per-token
     syntax colour inside a fence hit the identical ceiling (both are
     per-range styling) and were not attempted for the same reason.
     `markdown.rs`'s degraded rendering (backticks kept literally,
     `[text](url)` shown as `text (url)`) is the honest fallback,
     documented at the point it is produced.
  3. **Bottom-anchored virtualised list, paged, hold-top-edge on
     expand -- mostly shown, with one real gap in the anchor API.**
     `VirtualScroll<dyn Widget>` holds all 854 folded rows;
     `overwrite_anchor` before swapping a tool row's widget for its
     expanded/collapsed version is exactly the primitive
     `holdTopEdge` needs, and it worked: `e2-expand.png` shows the
     row growing downward from the same top edge it had collapsed,
     no jump. Virtualisation is real (`ui-trace elements` only ever
     lists the rows currently on screen, never all 854). **What did
     not come free: hugging the bottom of the screen.**
     `VirtualScroll::new`'s doc says "the item at `initial_anchor`
     will have its top aligned with the top of the scroll area" --
     so anchoring on the last row puts that row's top at the
     viewport's *top*, with empty space below it, not at the
     viewport's bottom the way a chat transcript wants (visible in
     `e2-screenshot2.png`). The complete public `WidgetMut` surface of
     `VirtualScroll` is `new`, `with_valid_range`,
     `will_handle_action`, `add_child`, `remove_child`, `child_mut`,
     `set_valid_range`, `overwrite_anchor`
     (`masonry/src/widgets/virtual_scroll.rs:257-428`) -- no
     scroll-offset setter and no reverse/bottom-up layout mode exist
     to ask for the other behaviour. Backward paging beyond the
     initial 800 was not exercised, per the scope cut above.
  4. **The soft keyboard -- inherited gap, not re-investigated.** E2's
     screen has no `TextInput`, only read-only `Prose`/`Button`, so it
     does not hit `masonry/src/lib.rs:531`'s `as_input_connection`
     returning `None` directly -- but it would the moment a composer
     is added, per E1's finding. Nothing new to add here.
  5. **Platform integration -- out of scope by design.** Foreground
     service, notifications, share sheet, deep link, Keystore,
     camera, back gesture, edge-to-edge, local-network permission are
     E3's list in RUST.md's own experiment order, not E2's.
  6. **Accessibility names -- shown, and the bench-script dependency
     actually exercised.** `ui-trace record --do "tap '> 3 tool
     calls'"` found the button by its label and pressed it (that tap
     is what produced `e2-expand.png`); `Prose` rows surface their
     text as their accessible name too (`ui-trace elements` lists
     "You said: One more short reply..." etc. as named nodes). Tap by
     name, the rule this whole project's bench scripts depend on,
     works against this screen.
  7. **Measurable frames -- blocked, and this is the finding E2 was
     really testing for.** Two separate problems, one of them fatal
     to the render-numbers half of this box's own pass condition.
     First, Masonry has no render-report/per-widget-cost
     instrumentation the way Compose's `DebugStats` gives this
     project -- building one was out of scope here. Second, and this
     is the one that matters: **neither of Masonry's two scrolling
     widgets responds to a touch drag at all.**
     `VirtualScroll::on_pointer_event`
     (`masonry/src/widgets/virtual_scroll.rs:504-523`) and
     `Portal::on_pointer_event`
     (`masonry/src/widgets/portal.rs:259-267`) both match only
     `PointerEvent::Scroll` (wheel/trackpad deltas) and do nothing
     with `PointerEvent::Down`/`Move`/`Up` -- there is no drag-to-scroll
     gesture logic anywhere in the widget set. `android-view`'s own
     Java bridge keeps the two paths separate at the source:
     `RustView.java`'s `onTouchEvent` forwards raw touch straight to
     Rust, and only `onGenericMotionEvent` (mouse/trackpad, not
     touch) reaches the `ACTION_SCROLL` branch that becomes
     `PointerEvent::Scroll`
     (`android-view/src/events.rs:530`). Confirmed empirically, not
     just by reading: a real swipe (`ui-trace`'s `swipe 540 1600 540
     400 300`, twice) moved nothing (`e2-scroll.png` is pixel-identical
     to the screen before it), and a synthetic Android wheel event
     (`adb shell input scroll 540 1200 --axis VSCROLL,-5`) also moved
     nothing. **This means `transcript-bench.sh`'s own gesture --
     a finger swipe -- cannot scroll a Masonry transcript on Android
     today, at all, on this framework commit.** So the "render
     numbers land within the Compose baseline" half of this box's
     pass condition cannot be attempted, let alone met: there is no
     way to perform the scroll the comparison asks for. This is not
     a performance shortfall to close by writing faster code: it is
     an absent input path upstream. The fix is a drag-to-scroll
     gesture in `on_pointer_event` (the same place `TextArea`'s own
     caret-drag logic already lives, so the pattern -- capture on
     `Down`, accumulate delta on `Move`, release on `Up` -- exists
     in this codebase already, just not wired into either scrolling
     widget), and it belongs upstream in `xilem` rather than in this
     project.
  
  **Net for RUST.md's recommendation.** Item 3 ("decide when the
  transcript screen exists in both, from the measurements") cannot be
  decided by a render-number comparison yet, because the comparison's
  own gesture does not work on Masonry on Android. What *can* be
  compared today is structural: iris already has a working scroll
  gesture and a working touch model (I2, 2026-09-05) that Masonry's
  upstream commit does not yet have for this exact case. That is a
  point in iris's favour that a frame-time number would not have
  shown any more clearly.
  

• E3 — the shell (2026-09-05). Both pass-condition proofs held on the emulator: a notification arrived while the app was closed, and a shared text share landed as a real message in a session's transcript. Committed to this repo (unlike E1/E2's external, uncommitted trees), since this is lightweight glue rather than a multi-gigabyte native build.

  *Where it lives.* `android-shell/` (new crate, `client-core` as its
  only real dependency) is the JNI bridge; `app/shellApp/` is a **new
  Gradle module**, not a rewrite of `app/androidApp` in place --
  that module is ~13,000 lines of working Compose UI this experiment
  does not touch or risk, and the two install side by side on one
  development device. `app/shellApp`'s manifest, channel names,
  notification wording and share intent-filter are copied from
  `androidApp`'s (`Notifications.kt`, `Share.kt`, the manifest) per
  AGENTS.md's "reuse rather than re-derive" -- see each file's own doc
  comment for exactly what was carried over. Two deliberate
  differences, both practical rather than behavioural: application id
  `com.example.aiapp.shell` and deep-link scheme `aiappshell` (not
  `aiapp`), so this experiment's install cannot collide with the real
  app's enrollment or Keystore alias on the same phone -- see
  `android-shell/src/settings.rs`'s `SCHEME` doc.
  
  *The Java floor, and one line more than planned.* Two classes,
  matching "How much Java is unavoidable" almost exactly:
  `MainActivity.java` (`onCreate`/`onNewIntent` forward to
  `nativeHandleIntent`) and `NotificationService.java`
  (`onStartCommand`/`onDestroy`/a `sync()` companion, three natives).
  Both ~30 lines including the license-free boilerplate Java itself
  demands (imports, `System.loadLibrary`). **One addition the analysis
  did not anticipate**: `MainActivity.toast(Context, String)`, a
  plain (non-native) static method Rust *calls* rather than
  implements, because posting a `Toast` from `share.rs`'s background
  thread needs a hop back to the main looper
  (`new Handler(Looper.getMainLooper()).post(...)`), and JNI can call
  an existing Java method on any thread but cannot construct a Java
  `Runnable` to hand to `Handler.post`/`runOnUiThread` without a
  reflection proxy uglier than three lines of Java. Recorded here
  because "the floor is two classes of ten lines" undersold this by
  exactly one small, call-only method -- the pattern (Rust calls
  Java, never Rust implements a Java interface) is worth keeping the
  next time this floor is estimated.
  
  *What client-core gained.* `notifications.rs`: `SessionNotification`,
  `NotificationKind` (mirroring `server/src/session/mod.rs`'s wire
  shape field-for-field) and `follow_notifications`, the SSE parse
  over `/notifications` built on the same `sse::SseReader` and
  `Transport` trait `event_stream.rs` already uses. `attention_line`
  is ported verbatim from `Notifications.kt`. 3 new tests (88 total in
  the crate); `android-shell` itself has none, since every function in
  it needs a live `Env` and there is no pure logic left to test in
  isolation once client-core owns the parsing -- matches E2's
  precedent ("a throwaway screen, not a library").
  
  *Scope cuts, each recorded at its own point in the code rather than
  only here:*
  - **Text-only share.** `Intent.EXTRA_TEXT` becomes a session message;
    a shared file/photo URI is not uploaded, because `client-core`'s
    `ApiClient` has no `/sessions/{id}/attachments` route yet either
    (`CLIENT_CORE.md`'s own "not covered" list) -- porting
    `Attachments.kt`'s `ContentResolver` reads and bitmap downscaling
    is real work belonging to whichever caller needs it next, not a
    detour inside this box.
  - **No session picker.** With no screen drawn yet (E4's job), a
    share attaches to whichever session has the latest
    `last_activity` -- documented as a placeholder in `share.rs`,
    not a designed behaviour.
  - **No banner/on-screen suppression.** `notify::show` skips
    `Notifications.kt`'s "nothing if this session is on screen" /
    "hand to the app as a banner" branches entirely: both read
    process-wide state that only means something once a screen
    exists to register against it, so every notification here takes
    the platform-drawer branch -- which is also exactly what the pass
    condition asks for. Revisit once E4 draws something.
  - **Keystore is not reimplemented in Rust.** `settings.rs` calls
    `wg-app-link`'s existing `ServerStore`/`ServerSettings` Kotlin
    classes over JNI rather than re-deriving the AES-GCM sealing:
    that code is shared with Dev Updater, already tested, and tied to
    a Keystore alias an existing enrolled phone depends on. This does
    mean `kotlinc` stays in the toolchain regardless of what E5 does
    with `javac`/`d8` for this module's own two classes -- a
    correction to "Can the APK be built without Gradle?"'s assumption
    that dropping Kotlin drops `kotlinc` outright; it drops it for
    *this app's own code*, not for a shared submodule pulled in as a
    dependency.
  
  *`jni` 0.22, not the older API most examples assume.* This is a
  real API split (`Env` for real work, `EnvUnowned` as the FFI-safe
  type a native fn receives, joined by `EnvUnowned::with_env`), and
  the `native_method!` macro (used for all four natives here, via
  `const _: NativeMethod = native_method! { ... }`) generates both the
  mangled `Java_...` export and the panic/error-handling wrapper from
  one Rust function signature -- chosen over hand-written
  `#[unsafe(no_mangle)] extern "system" fn Java_com_..._method` because
  a hand-typed export name and a hand-typed JNI signature string
  routinely drift from the Java they claim to match, silently (see
  the next two findings, both of which were exactly that drift).
  `error_policy = LogErrorAndDefault` reports a failure to logcat
  rather than throwing it back into Java as an exception that would
  crash the app over something recoverable -- matching
  `Notifications.kt`'s own "log, don't crash" posture, but it is a
  no-op without a logger backend (`android_logger`, Android-only
  dependency, `lib.rs`'s `ensure_logger`) installed; the class of bug
  this exists to report was found once with no logger and read as
  nothing having gone wrong at all.
  
  **Three real findings, each cost a failed run before being
  diagnosed, each written where the fix lives so a reader who touches
  that file again does not lose an afternoon to it:**
  
  1. **A generic `JObject` parameter type silently exports the wrong
     JNI signature.** `native_method!`'s shorthand
     `fn native_sync(context: JObject) -> ()` encodes the export as
     `(Ljava/lang/Object;)V`, because it has no way to know the
     intended Java type is `android.content.Context` from a bare
     `JObject`. The real Java method is declared
     `(Landroid/content/Context;)V`; the two mangled names never
     resolve to each other, and the failure is
     `UnsatisfiedLinkError: No implementation found`, thrown the
     moment Java calls it -- not a build error on either side. Fixed
     by spelling each parameter as its actual Java type in the macro
     invocation (`context: android.content.Context`, `activity:
     android.app.Activity`, ...), which the macro accepts directly
     per its "Java Object Types" syntax, while the Rust implementation
     function keeps the parameter as plain `JObject` (the "Built-in
     Types" fallback for a Java class with no dedicated Rust
     wrapper). `lib.rs`'s comment beside the first `native_method!`
     call is the citation.
  2. **A class looked up by name from this crate's own background
     thread fails, and only for app classes.** `android-shell`'s
     follow-loop and share threads are Rust-spawned and attached via
     `JavaVM::attach_current_thread`, which the platform never handed
     an app `ClassLoader` -- so `FindClass`'s default fallback (used
     internally by `find_class`/`new_object`/`call_static_method`/
     `get_static_field`, anything that resolves a class *by name*
     rather than from an object it already holds) only reaches the
     bootstrap loader's framework classes. `androidx.core.app.
     NotificationManagerCompat`, packaged inside this app's own APK,
     is invisible from there: `Error::NoClassDefFound`, logged by
     `notify::show`'s `LogErrorAndDefault` as "failed to resolve Java
     class ... (class not found or linkage error)" -- which on a real
     device is indistinguishable from "the notification silently
     never arrives," since the *ongoing* foreground notification
     (built on the main thread, before this thread exists) posts
     fine regardless, so nothing else looks wrong. Fixed in
     `jcall.rs`: `remember_class_loader` caches the app's own
     `ClassLoader` (`context.getClass().getClassLoader()`) the first
     time any entry point with a `Context` runs, and every
     class-by-name lookup goes through `LoaderContext::Loader`
     explicitly rather than the thread-dependent default -- correct
     on the main thread and this crate's background threads alike.
     `jcall.rs`'s module doc has the full account.
  3. **`onStartCommand` spawning a thread unconditionally opens a
     second connection, and `Notifications.kt` has the same bug.**
     Enrolling calls `sync()` twice in one launch (once
     unconditionally in `MainActivity.onCreate`, again inside
     `handle_enrollment` after saving the token), each of which starts
     the service, and Android runs `onStartCommand` once per start
     request -- so the follow-loop thread was spawned twice, caught on
     `adb logcat` as two `jni::vm::java_vm: Attached thread
     ai-app-notifications` lines for one enrollment. Kotlin's
     `onStartCommand` has the identical shape (`thread(isDaemon =
     true) { follow(settings) }`, no guard), so this is a latent bug
     in the reference implementation this port found by testing
     rather than something E3 introduced -- worth carrying the same
     guard back to `Notifications.kt` separately, not done here.
     Fixed in `notify.rs` with a `RUNNING` `AtomicBool`, `swap`ped
     true before spawning and reset in `on_destroy`; see its doc
     comment for the accepted race this shares with the pre-existing
     `STOPPING` gap below.
  
  **Known gap, not fixed, written where it will be found.**
  `notify.rs`'s `STOPPING` flag (checked between reconnects) cannot
  interrupt a `ureq` read already blocked inside one connection --
  unlike `HttpURLConnection.disconnect()`, `client_core::Transport`
  exposes no cancellation handle. `/notifications` is idle between
  events (a keep-alive), so in practice a stop is a bounded wait
  rather than a hang; closing this for real means adding a
  cancellation point to the `Transport` trait itself, a decision
  affecting every caller, not an `android-shell`-only fix.
  
  *Verification, exact commands.* `cargo fmt -- --check`,
  `cargo clippy --all-targets` (zero warnings) and `cargo build`
  clean for both `client-core` and `android-shell` on the host
  target; `cargo ndk -t x86_64 -P 26 clippy --all-targets` clean for
  `android-shell` on the Android target too (the `android_logger`
  dependency is Android-only, so this is the only way to compile-check
  it). `./run-tests.sh` from the repo root: 127 `server` tests, 88
  `client-core` tests (85 + the 3 new to `notifications.rs`), all
  passing -- the port added no regression to what already worked.
  `./gradlew :shellApp:lintDebug`: `No issues found` (the report at
  `app/shellApp/build/reports/lint-results-debug.txt`).
  
  *The two pass-condition proofs*, both on this checkout's own AVD
  (`ai-app-2`, GPU host per the default, torn down with `emu down`
  when this session finished) against `app/ui-sandbox.sh`:
  
  - **Notification with the app closed.** Enrolled via
    `adb shell "am start -a android.intent.action.VIEW -d
    'aiappshell://enroll?host=10.0.2.2&port=<sandbox port>&token=<token>'"`
    (per the sandbox's own banner, substituting the scheme), granted
    `POST_NOTIFICATIONS`, pressed home, then
    `./ui-sandbox.sh spawn e3notif2` and
    `./ui-sandbox.sh send <sid> "/question Should I proceed with the deploy?"`.
    `adb shell dumpsys notification --noredact` shows a
    `channel=sessions` record, `android.title=e3notif2`,
    `android.text=Waiting for you` (matching `attention_line` and the
    session's own title, exactly what `Notifications.kt` would have
    shown) -- posted while the app held no visible activity. Tapping
    it (`ui-trace record --do "tap 'e3notif2'"`, found in the
    expanded shade after `adb shell cmd statusbar
    expand-notifications`) launched
    `com.example.aiapp.shell/.MainActivity` with
    `dat=aiappshell://session/...`, confirmed in `adb logcat`'s
    `ActivityTaskManager: START` line -- the `PendingIntent` names
    the right session.
  - **A share lands in a session.** With the app enrolled and a
    session already active,
    `adb shell "am start -a android.intent.action.SEND -t text/plain
    --es android.intent.extra.TEXT 'Please check the deploy logs for
    errors.' -n com.example.aiapp.shell/.MainActivity"` (the classic
    `adb shell` quoting trap from `this-machine-android` applies here
    too: the whole `am start` invocation has to be one single-quoted
    string handed to the *remote* shell, or the extra's spaces get
    re-split away). `./ui-sandbox.sh api
    '/sessions/<sid>/transcript?limit=20'` shows
    `{"type":"userMessage","text":"Please check the deploy logs for
    errors."}` followed by the echo driver's reply -- the share
    reached the most-recently-active session as a real message, not
    a mock.
  

• E4 — the same screen on the desktop in a winit window, from the same crate, with only the layout differing.

• E5 — the packaging xtask (2026-09-05). Both pass-condition proofs held on this checkout's own emulator: adb install -r of the xtask-built APK over the Gradle-built one succeeded, and the notification service reached its follow-loop and posted a real notification while the app was backgrounded. cargo xtask apk at the repo root (.cargo/config.toml's alias for cargo run --manifest-path xtask/Cargo.toml --) runs cargo ndk → javac/d8 → aapt2 → zipalign → apksigner with no Gradle driving the packaging itself -- one disclosed exception, below.

  *Where it lives.* `xtask/` (new, independent crate at the repo
  root -- **no Cargo workspace**, matching every other crate here;
  `run-tests.sh` already `cd`s into each rather than assuming one).
  **Zero dependencies**: every step is "run this SDK/JDK tool with
  these arguments and check its exit status," which needs nothing a
  crate would add (AGENTS.md's "new dependencies need a reason").
  `src/sdk.rs` finds the SDK root/build-tools/`android.jar` the same
  way `app/android-env.sh` does ($ANDROID_HOME, then
  $ANDROID_SDK_ROOT, then `~/Android/Sdk`); `src/keystore.rs`
  finds-or-generates the release key with the exact recipe
  `app/build-apk.sh` uses (same env vars, same path, same `keytool`
  invocation) so the two tools sign with the *same* key, plus a
  `--debug` path using the conventional `~/.android/debug.keystore`;
  `src/apk.rs` is the pipeline itself, `src/main.rs` the ~40-line CLI.
  About 420 lines total against RUST.md's earlier "about 150" guess --
  the difference is almost entirely dependency handling (below), which
  the earlier estimate didn't anticipate.
  
  *`:link`'s `kotlinc` question, resolved.* Checked first, since E3
  left it open: no standalone `kotlinc` exists on this machine (not on
  PATH, not under any SDK -- only `kotlin-compiler-embeddable` jars
  inside Gradle's own distributions). So the choice was never
  "invoke kotlinc" versus "port `ServerStore`/`ServerSettings` to
  Java" as originally framed -- a third route fell out of solving the
  *other* open dependency problem (androidx, next paragraph): the one
  Gradle call already needed for that also compiles `:link`'s Kotlin
  as a side effect, via Gradle's own embedded compiler, and hands back
  the resulting `classes.jar` in the same resolved-jars list. That is
  RUST.md's own "prebuild it once into a jar/aar E5 consumes as a
  binary input" option, arrived at for free rather than built
  specially -- no Java port of `ServerStore` was written, and
  `android-shell/src/settings.rs`'s JNI class-by-name lookup
  (`com/example/wgapplink/ServerStore`) needed no change.
  
  *One disclosed exception to "no Gradle in the loop": dependency
  resolution.* `app/shellApp` depends on `:link` (Kotlin, above) and
  on `androidx.core:core-ktx` -- not a compile-time dependency of the
  two Java stub classes (`MainActivity`/`NotificationService` import
  only `android.*`), but a **runtime** one: `android-shell/src/notify.rs`
  reaches `NotificationCompat`/`NotificationChannelCompat`/
  `NotificationManagerCompat`/`ServiceCompat`/`ContextCompat` by class
  name over JNI, so their bytecode has to be in the final dex even
  though nothing in this pipeline's own Java source mentions them.
  Reimplementing a Maven/AAR dependency resolver to avoid one Gradle
  call was not a good trade against "smallest honest route" (the
  standard this file already applied to `kotlinc`) -- so
  `app/shellApp/build.gradle.kts` gained one task,
  `printRuntimeClasspathJars`, which asks the `releaseRuntimeClasspath`
  configuration for its artifacts through an `ArtifactView` requesting
  the `android-classes-jar` attribute (the same post-AAR-transform
  view AGP's own dexing task consumes, so an AAR is already unpacked
  to a plain `.jar` by the time the xtask sees it) and writes their
  absolute paths, one per line, to
  `app/shellApp/build/xtask/runtime-classpath.txt`. `cargo xtask apk`
  runs `./gradlew :shellApp:printRuntimeClasspathJars` once (a few
  seconds, mostly UP-TO-DATE on a warm Gradle daemon), reads that file,
  and hands every jar in it to `d8` as an ordinary program input --
  `:link`'s `classes.jar` among them, per the paragraph above. Nothing
  past that one call touches Gradle. **What this trades away**: the
  pipeline is not Gradle-free end to end, only Gradle-free for the
  part that was actually expensive (assembling and dexing the app's
  own code, which the earlier options -- kotlinc, or a hand-rolled
  resolver -- were the two ways to avoid entirely). Recorded here
  rather than left implicit, matching how the `kotlinc` compromise
  above is recorded.
  
  *The rest of the pipeline, in order (`apk.rs`):* `cargo ndk -t
  arm64-v8a -t x86_64 -P 26 -o app/shellApp/src/main/jniLibs/ build
  --release -p android-shell` (both ABIs by default -- real phone and
  this machine's emulator -- `--abi` overrides; always `--release`
  for the native library regardless of the APK's signing variant, for
  the reason E1 already established: a debug build's Vulkan
  object-labelling segfaults this emulator's driver, and there is no
  reason for a signing choice to make this crate's `.so` bigger).
  `javac -cp android.jar` compiles `MainActivity.java`,
  `NotificationService.java` and a freshly generated `PinnedCa.java`
  (same template as the Gradle `generatePinnedCa` task, same
  opening-quotes-adjacent-to-`"""` rule from AGENTS.md's "Things that
  have bitten") into one `classes.jar` (`jar cf` -- `d8` rejects a
  bare directory of `.class` files outright, "Unsupported source file
  type", discovered by trying it). `d8 --release --min-api 24 --lib
  android.jar` dexes that jar plus every classpath jar from the
  paragraph above into one `classes.dex` (no multidex needed at this
  size). `aapt2 link` compiles `app/shellApp/src/main/AndroidManifest.xml`
  into the base APK's `resources.arsc` -- the checked-in manifest has
  no `package` attribute (Gradle injects one from `android.namespace`
  during a manifest merge this pipeline doesn't run), so `apk.rs`
  writes a copy with `package="com.example.aiapp.shell"` spliced in
  rather than editing the source manifest, and refuses to run at all
  if the source ever gains one of its own (a version-drift guard
  cheaper than a real merge). `--min-sdk-version`/`--target-sdk-version`/
  `--version-code`/`--version-name` are passed on the command line for
  the same reason -- the raw manifest carries none of them, Gradle's
  `defaultConfig` normally does. `jar uf` (not a hand-rolled zip
  writer -- `jar` ships with the JDK this pipeline already needs)
  merges `classes.dex` and a staged `lib/<abi>/libandroid_shell.so`
  tree into the base APK (cargo-ndk's `-o` writes
  `jniLibs/<abi>/*.so`, matching the Gradle source-set layout it was
  pointed at; Android's own zip convention wants `lib/<abi>/*.so` at
  the archive root, hence the staging copy rather than an in-place
  rename). `zipalign -f -p 4` then `apksigner sign` finish it, signed
  with `~/.config/ai-app/release.jks` by default or
  `~/.android/debug.keystore` under `--debug`. The signed APK is
  copied to `xtask/build/outputs/apk/<mode>/ai-app-shell-<mode>.apk`
  as a final step -- a Gradle-shaped path (`*/build/outputs/apk/*/*.apk`)
  chosen so Dev Updater's fixed-pattern APK discovery
  (`~/repos/dev-updater/server/src/discover.rs`'s `APK_PATTERNS`,
  which has no per-component path override) finds it without any
  change on that side; the working files above it stay under
  `target/xtask/apk/`, an ordinary build-cache location (gitignored,
  along with `xtask/target/`).
  
  *Wired into `.dev-updater.ron`*: a second `Apk` component, `shell`,
  `build: "cargo xtask apk"`, `modes: ["release", "debug"]`, no `cwd`
  (defaults to the checkout root, which both the `cargo xtask` alias
  and the publish path above need -- `.cargo/config.toml`'s alias
  resolves its `--manifest-path` relative to the *invoking* working
  directory, not to where the config file lives, which is what ruled
  out giving this component its own `cwd`). Dev Updater's `ByMode`
  appends the chosen mode word as the command's last argument
  (`build-apk.sh`'s own interface, per that component's comment), so
  `main.rs` accepts bare `release`/`debug` as well as `--release`/
  `--debug` for typing by hand. The existing `app` component
  (`build-apk.sh`, Gradle) is untouched.
  
  *Verification.* `cargo fmt -- --check` and `cargo clippy
  --all-targets` clean, zero warnings, for `xtask` (host target --
  nothing in it is Android-specific; it *runs* `cargo ndk`, it isn't
  cross-compiled itself). `./run-tests.sh`: 127 `server` + 88
  `client-core` tests, unaffected, still passing. `apksigner verify
  --print-certs` on the xtask's release output confirms a V3 signer
  with `CN=ai-app` -- the same key `build-apk.sh` generates.
  
  *The two pass-condition proofs*, both on this checkout's own AVD
  (`ai-app-2`, GPU host, brought up and torn down within this
  session):
  - **Installs over the Gradle-built one.** Built the Gradle release
    variant first (`AI_APP_KEYSTORE=~/.config/ai-app/release.jks
    AI_APP_KEYSTORE_PASSWORD=$(cat
    ~/.config/ai-app/release.jks.password) ./gradlew
    :shellApp:assembleRelease` -- needed its own signing block added
    to `app/shellApp/build.gradle.kts`, copied from `androidApp`'s,
    since `shellApp` had none before this), installed it fresh
    (`adb uninstall com.example.aiapp.shell` first -- an older debug
    install from E3 testing was signed with a different key and
    `install -r` over it fails loudly with
    `INSTALL_FAILED_UPDATE_INCOMPATIBLE`, which is the correct,
    expected failure for a mismatched key rather than a bug), then
    `adb install -r xtask/build/outputs/apk/release/ai-app-shell-release.apk`:
    **`Success`**.
  - **The notification service starts.** Enrolled via
    `adb shell "am start -a android.intent.action.VIEW -d
    'aiappshell://enroll?host=10.0.2.2&port=<sandbox port>&token=<token>'"`,
    force-stopped the app, then re-launched it once (enrollment calls
    `sync()` from `MainActivity.onCreate`). `adb logcat` shows
    `ActivityManager: Background started FGS: Allowed ... intent:
    ... cmp=com.example.aiapp.shell/.NotificationService`, immediately
    followed by `android-shell: jni::vm::java_vm: Attached thread
    ai-app-notifications`, a real TLS handshake to the sandbox's
    `10.0.2.2:<port>`, and `Response { status: 200 ... }` on
    `/notifications`. Pressed home, spawned a sandbox session and sent
    it `/question Should E5 proceed?`; `adb shell dumpsys notification
    --noredact` then shows a live `NotificationRecord` for
    `com.example.aiapp.shell`, `channel=sessions`, `tag=<session id>`
    -- posted while the app held no visible activity, the same bar
    E3's own proof cleared.
  
  *Left undone, honestly.* No attempt to shrink the dex (R8/minify is
  off, matching `shellApp`'s existing `isMinifyEnabled = false`, so
  the APK carries the full unshrunk `androidx`/Kotlin-stdlib/coroutines
  graph -- about 5.2 MB signed with both ABIs, most of it native
  libraries and that dependency graph rather than this project's own
  code). No `--abi arm64-v8a`-only real-device install was attempted
  this session (no physical phone reachable from here); the emulator
  proof above is `x86_64` plus a cross-compiled but unexercised
  `arm64-v8a` `.so` in the same APK. Multidex is unneeded at today's
  size but nothing in `dex()` checks for the 64k-method ceiling should
  the dependency graph grow.
  

The iris track

These build iris up to carry the app. Each is a feature added to iris with a pass condition, in dependency order. Work in iris/ in this repository on the rustify branch, and record in this file what each step measured.

• I0a — where iris lives (decided 2026-09-04). For now it is vendored at iris/ in this repository, history not carried, and consumed by path. Iris's decision: keep it close while it is being reshaped for this app, and give it back its own repository — iris/iris on the gitea remote, which already holds the full 244-commit history, on a branch of its own — once it has proved itself. The vendored tree is that repository's main at 7b54aaf ("readme", 2026-01-29), byte-identical to the public GitHub copy, so a later reconciliation has a known base. A crate that uses it says iris = { path = "../iris" }.

• I0b — make it build here (done 2026-09-04). iris now builds, clippy-clean and rustfmt-clean at the defaults, on a pinned dated nightly, and the tabs example draws on this VM's GPU.

  **The pin** is `nightly-2026-09-03` (rustc 1.100.0-nightly,
  `2e2b193f8`), declared in `iris/rust-toolchain.toml` along with the
  `clippy`/`rustfmt` components and the two Android targets, so a
  fresh clone provisions itself. It is dated rather than `nightly`
  because the whole failure below was a rolling channel moving under
  an unattended build. Installed with `--profile minimal`: 912 MB.
  
  **The 36 errors were one syntax change, and the earlier diagnosis in
  this file was wrong.** It is not that a trait must now be declared
  `const trait` — the vendored tree already declares them that way,
  which is how it was written in January. What changed is the *impl*
  keyword order: `impl const Trait for T` is now
  `const impl Trait for T`, and generics go on the `impl`
  (`const impl<T: [const] Foo> Bar for T`). Bounds are unaffected;
  `T: const Foo`, `T: [const] Foo` and `impl const Foo` in argument
  position all still compile. Everything else — the unresolved
  `UiVec2`/`Vec2`/`impl_op` imports, and a `Color<u8>` that resolved
  to `wgpu_types::Color` — cascaded from the seven files that failed
  to parse. The rewrite was mechanical across 20 sites and took the
  workspace from 36 errors to 0.
  
  **`#![feature]` gates, 12 after this step** (two were declared and
  unused, and were removed: `map_try_insert`, `const_cmp`).
  Load-bearing and worth watching: `const_trait_impl`, `const_ops`,
  `const_convert`, `const_destruct` are the const-traits family and
  the one that has already broken once — they move together, so
  advancing the pin means re-reading this section. `unboxed_closures`
  + `fn_traits` (postfix builder API) and `unsize` +
  `coerce_unsized` (widget handles) are pairs. The rest are
  individually small: `macro_metavar_expr_concat`, `portable_simd`,
  `associated_type_defaults`, `option_into_flat_iter`, and `gen_blocks`
  in the top crate.
  
  **Running it headless.** `iris/run-headless.sh EXAMPLE [--shot PNG]`
  with `iris/headless.conf`, the same trick `emu` uses: a headless
  sway, and `grim` for the picture. It deliberately starts its *own*
  compositor rather than joining `emu`'s — sway tiles, so adding a
  window to the one an emulator sits in resizes that emulator.
  Unlike `emu`'s it disables Xwayland, since winit speaks Wayland.
  **This VM has a real GPU for this**: Vulkan 1.4 through Venus onto
  the host's RX 7900 XT, and GL 4.6 through virgl — so desktop wgpu
  work here is not software-rasterised, unlike inside the emulator.
  
  **iris has no tests at all** (`cargo test --workspace`: 0 passed
  across 6 targets). Nothing to keep passing, and nothing to catch a
  regression — worth knowing before I1 changes the text stack.
  
  **`iris-core` no longer depends on winit, and now cross-compiles to
  Android.** It wanted exactly one thing from it — `PhysicalSize<u32>`
  in `UiRenderNode::resize`'s signature, for two numbers it immediately
  turned into floats — and that pulled a whole windowing backend into
  the layer below it, the wrong direction. `resize` takes
  `impl Into<Vec2>` now, like `UiRenderState::resize` beside it already
  did. The consequence is the point: with winit in the graph an Android
  build of the core failed in `android-activity` (which needs a backend
  feature nothing here selects), and without it
  `cargo ndk -t arm64-v8a -P 26 build -p iris-core` finishes in 30s and
  produces an rlib, wgpu's Android backend included. So **iris's
  widget, layout and render core already builds for the phone**, and
  what I2 has to supply is the surface, the input and the IME — not a
  port of the library.
  
  **Build weight, cold, on this VM's 8 cores** (`rm -rf target`, then
  `cargo build --example tabs`), since "the Linebender stack is slow in
  debug" was the worry behind this question: plain debug **43s** and a
  2.1 GB `target/`; with the `[profile.dev.package."*"] opt-level = 2`
  knob, **1m46s** and 1.5 GB. So iris's own wgpu + winit + cosmic-text
  graph is not the slow thing — which makes it a calibration for E1
  rather than an answer about Masonry, whose graph adds Vello, Parley,
  Fontique and Skrifa. Runtime cost of the knob was not measured here.
  
  **Fixed: iris never called `pre_present_notify`.** The symptom was
  that about one start in five kept the window's 800x600 startup layout
  on a 1920x1200 surface for good. What settled it was tracing iris's
  own decisions into memory and dumping them from another thread —
  `eprintln!` in the draw path makes the defect vanish, which is why
  earlier attempts kept losing it. The traces from a good and a bad run
  are **byte-identical**: both lay out and draw `redraw_all at
  (1920, 1200)` into a 1920x1200 texture with `suboptimal=false`. iris
  was drawing the right frame every time; the compositor was still
  showing the first one, and forcing a full repaint did not shift it.
  What was missing is winit's `Window::pre_present_notify`, called
  immediately before `present`, which on Wayland is what ties the
  commit to the surface's frame callback. Without it a frame drawn with
  nothing following it can sit unpresented with nothing left to flush
  it — which is exactly a window that has just settled after its
  opening resize. Measured: **0 bad in 40** with the fix, against 4 in
  20 before it, and — the stronger evidence — 0 in 20 in the
  instrumented configuration that had been 15 in 20. Runtime resizing
  still round-trips to a byte-identical layout.
  
  Two things ruled out on the way, both worth not re-trying: the
  present mode (the fault survived the move from `AutoNoVsync` to
  `AutoVsync` at the same rate) and the size cache (`redraw_all` clears
  it). A `desired_maximum_frame_latency` of 1 moved the rate without
  fixing it, and was reverted. Iris's own note that she had never seen
  the library fail to resize was the useful steer: it pointed away from
  the layout code, where two hours had already gone.
  
  One thing was fixed on the way, and it is not that bug: `update`
  redrew everything when `resized` was set, but `needs_redraw` — which
  is what decides whether to *ask* for a frame — did not know about
  `resized` at all. The two now share one `needs_redraw_all`, since a
  condition in one and not the other is a frame nobody requests. It is
  latent on Wayland only because winit asks for a redraw after a resize
  by itself; on Android, where the surface work of I2 will not have
  winit underneath it, nothing else here would have asked.
  

• I1 — parley, and a glyph atlas (done 2026-09-04). No bake-off: Iris decided for parley directly ("I wanted to switch it to parley anyways"), and then asked for the atlas as well ("just do the atlas, commit to it, we do want it"). Both are in.

  **What parley bought, beyond shaping.** Its editing model addresses
  text by byte offset into one string, where cosmic-text used
  `(line, index)` — so `select_content`, `delete_between`,
  `insert_inner` and `newline` collapse into ordinary string
  operations. Bigger: `Selection::geometry` and `Cursor::geometry`
  replace `iter_layout_lines`, `index_x` and `cursor_pos`, which walked
  runs by hand to place the caret and the selection boxes and were not
  bidi- or wrap-correct. `edit.rs` lost about 130 lines and gained
  Home/End. Its cursor motions map onto parley's `next_visual`,
  `previous_visual_word`, `next_line` and so on, in one function.
  
  **The atlas is what "text resizing (per frame) is really slow"
  was.** Every string used to be rasterised into its own `RgbaImage`
  and uploaded as a whole texture whenever anything about it changed,
  so a window resize re-rasterised and re-uploaded every visible
  string. Now a glyph is rasterised once per font, size and subpixel
  phase, shared by every string that contains it, and a resize
  re-emits quads without touching the GPU's copy. **The tabs example
  reports it: `views`, the number of texture views bound, went from 6
  to 1** — six per-string textures became one shared page. Supporting
  pieces: a `GLYPH` primitive that samples a sub-rectangle and tints
  it (the existing texture primitive samples a whole texture), a
  `Patch` texture update so a new glyph costs its own bytes rather
  than a 4 MB page, and `GpuTextures` keeping its `Texture`s, since a
  view cannot be written through.
  
  **Not yet measured**, and the honest gap in this step: the TODO's
  "really slow" was never given a number, so neither is the
  improvement. What is evidence rather than argument is the view count
  and the shape of the work — a resize no longer rasterises. A
  before/after timing wants the transcript screen of I5 to be worth
  taking.
  
  **Two bugs found on the way**, both pre-existing: `primitives!`'s
  `@count` rule recursed comma-separated while matching
  space-separated, so it terminated only for exactly two primitives
  and adding a third hit the recursion limit; and `Color` had no
  `Default`, which parley's `Brush` requires.
  
  **Fourteen tests**, iris's first. The editor is the one part that is
  pure logic rather than something needing a GPU and a window, and it
  was rewritten wholesale with no way to exercise it — synthetic input
  does not reach a client under the headless compositor, which has no
  seat devices. Two of the tests are aimed at what the rewrite could
  plausibly have broken: the IME preedit path, and editing multi-byte
  text now that offsets are bytes.
  
  Dropping cosmic-text and unicode-segmentation also retired two
  nightly gates — `portable_simd` (the old glyph compositing) and
  `gen_blocks` (the deleted line iterator). **Eleven left.**
  

iris's binding array does not survive real Android hardware (found 2026-09-04, resolved 2026-09-04)

Resolved the same day: see "Where things stand" above and TEXTURES.md's "Implemented, 2026-09-04". The measurement and sourcing below are unchanged and are why the fix looks the way it does; nothing here needs re-checking on its own account.

Iris asked, of the "unknown number of images" case — a transcript with an unbounded number of attached screenshots — whether iris's approach even works on a phone, since her recollection was that mobile does not support it. Checked rather than assumed, and the recollection is right, with sources rather than a guess.

What iris does today. Every texture — every Image widget (src/widget/image.rs) and every glyph atlas page — gets its own permanent slot in one array via Textures::add (core/src/primitive/texture.rs:65), and both the TEXTURE and GLYPH primitives sample it by view_idx into binding_array<texture_2d<f32>> at core/src/render/shader.wgsl:56, sized by UiLimits::default — 100,000 textures, 1,000 samplers (core/src/render/mod.rs:347). That needs three wgpu features: TEXTURE_BINDING_ARRAY, SAMPLED_TEXTURE_AND_STORAGE_BUFFER_ARRAY_NON_UNIFORM_INDEXING, PARTIALLY_BOUND_BINDING_ARRAY — Vulkan's VK_EXT_descriptor_indexing ("bindless"), promoted to core in 1.2. So a transcript with an unbounded number of images is exactly the case that grows this array without bound, one permanent slot per image.

Measured first on the emulator, and it fails outright. A rig (rigs/gpu-probe, a plain executable with no window, pushed with adb push and run from /data/local/tmp — no APK needed to ask a device what it supports) asks wgpu::Adapter::request_device for exactly iris's features and limits. Against the emulator's guest Vulkan — both SwiftShader (vk_swiftshader_icd.json) and lavapipe (lvp_icd.json, cold-booted) — request_device fails: Unsupported features were requested: TEXTURE_BINDING_ARRAY | SAMPLED_TEXTURE_AND_STORAGE_BUFFER_ARRAY_NON_UNIFORM_INDEXING | PARTIALLY_BOUND_BINDING_ARRAY. A second, raw query through ash (rigs/gpu-probe/src/vk.rs, bypassing wgpu) shows lavapipe's vkGetPhysicalDeviceFeatures2 actually reporting all seven descriptor- indexing sub-features as true at device api version 1.3 — so on this software renderer wgpu-hal's own feature detection is being more conservative than the driver, for a reason not chased further (a likely instance-version negotiation gap, since VK_EXT_descriptor_indexing was only promoted to core at 1.2 and wgpu-hal's own Instance::init may be requesting less). That part is an emulator/wgpu-hal question and not the finding that matters.

The finding that matters is about real phones, not the emulator, and it is sourced rather than recalled. The Android Vulkan Profile 2025 — Google and Khronos's current baseline, covering 80.1% of active Vulkan-capable Android devices as of October 2025 (developer.android.com/ndk/guides/graphics/android-vulkan-profile) — does not require VK_EXT_descriptor_indexing or any descriptor- indexing feature. It requires shaderSampledImageArrayDynamicIndexing (indexing an array of samplers by a value uniform across the invocation — Vulkan 1.0 baseline, unrelated to bindless) and stops there; the same is true of the 2021 and 2022 profiles. On the hardware side, Arm's own developer documentation states "VK_EXT_descriptor_indexing is supported on all Valhall and 5th Gen GPUs" (developer.arm.com/mobile-graphics-and-gaming/vulkan-api-best-practices-on-arm-gpus) — Mali generations from roughly 2019 (Mali-G77) onward, named affirmatively with no claim made for Bifrost, Midgard or Utgard, which are still common in budget and older Android phones still in use. So this is not a software-renderer artifact: a real, currently-shipping share of the Android fleet lacks the feature iris's texture pipeline asks for unconditionally, and the newest official baseline does not promise it either. (A crates.io/search-engine claim of "1% support on Android" for this extension was checked against its cited source, an Arm blog post, and was not actually there — that number does not appear anywhere primary and should not be repeated; the 80.1%-baseline-excludes-it finding above is the one with an attributable source.)

Recommendation, not yet implemented. iris already solved the identical problem for text in I1: the glyph atlas (core/src/render/atlas.rs) packs many small rasters into a handful of shared 1024×1024 pages and samples them by UV offset, so text needs none of the three features above — only ordinary single-texture sampling. The same technique generalizes to images: route an Image widget through a shared atlas when it is small enough to pack (thumbnails, downscaled attachment previews, avatars, icons), and fall back to one ordinary, non-array texture bind group — selected per batched draw call the way every immediate-mode 2D renderer already does — for anything too large to atlas well (a photo opened at full resolution). Either path is plain Vulkan 1.0 / GLES texture sampling, so it removes the descriptor- indexing requirement from iris's device request entirely, which is also what would make the emulator work regardless of the wgpu-hal question above: a device that never asks for the feature cannot be refused for lacking it. This is a change to iris's rendering core — the shader's binding group layout, Textures, the texture and glyph primitives, and ui/painter.rs — so it is written here as a recommendation rather than started, per the project's rule to confirm a load-bearing design change before making it. It should be resolved before I2 is called done, since I2's pass condition is the phone, not just the emulator, and this is exactly the kind of thing that passes on a desktop GPU and fails silently on real hardware.

• I2 — iris on android-view (2026-09-05). The android-view backend, the iris-android-app cdylib and Gradle shell, insets, the back gesture and the full InputConnection bridge are in and measured working; the tabs example now renders on the emulator (Vulkan/ SwiftShader and GLES/virgl both), and the composer's keyboard shows real Gboard suggestions through the IME bridge. See below for the render-gap root cause and fix.

  **Layout.** `iris/src/android/` mirrors `default/`'s module split
  (`view.rs` is `app.rs`+`state.rs` combined, since android-view has one
  harness type where winit splits `ApplicationHandler` from per-window
  state; `render.rs`, `input.rs`, `attr.rs` correspond directly;
  `ime.rs` and `insets.rs` have no winit counterpart). What used to live
  only in `default/` and had no winit dependency — `WidgetState`,
  `CursorState`/the sense machinery, `Tasks`, `Selector`/`Selectable`'s
  focus handling — moved to crate-root modules (`state.rs`, `sense.rs`,
  `task.rs`, `attr.rs`) so both backends use one copy; `Tasks`' redraw
  nudge is now behind a `RequestRedraw` trait (`Window` for winit, a
  `JavaVM`+`GlobalRef` attach-and-call for android-view) rather than a
  concrete `winit::window::Window`. `winit`/`arboard` and
  `android-view`/`send_wrapper` are now `[target.'cfg(...)']`
  dependencies, and `default`/`android` are target-gated modules,
  because winit's own Android support needs `android-activity` with a
  backend feature selected — exactly what `iris-core` was kept free of.
  Confirmed by trying it before the split (`cargo ndk -t x86_64 -P 26
  build -p iris` failed inside `android-activity` itself) and after
  (clean). `iris/tabs-ui` is the tabs example's widget tree factored out
  of `examples/tabs/main.rs` into a crate generic over `Rsc: HasEvents`
  + `Rsc::State: FocusHost`, so the winit example and
  `iris/android-app` (the new cdylib, excluded from the `iris` workspace
  because android-view needs the NDK sysroot to link — see that
  `Cargo.toml`'s comment) call the same `build()`.
  
  android-view pinned to `bec6c62a96cef8239b0fd7fedeef9b184d02e3a1`, the
  commit E1 measured against. `RustView.java`/`RustInputConnection.java`
  are vendored (no published AAR to depend on) into
  `iris/android-app/app/src/.../org/linebender/android/rustview/`, with
  one deliberate diff from upstream noted in a comment: `mViewPeer` is
  `protected` rather than package-private, so `IrisView` (a different
  package) can pass it to the window-insets native call android-view
  has no hook for.
  
  **Insets and the back gesture**, both without touching android-view.
  The back gesture takes no new plumbing at all: with no
  `OnBackPressedCallback` registered, Android still delivers it as an
  ordinary `KEYCODE_BACK` `KeyEvent` through the existing key path (the
  legacy behaviour every view-based app gets by default), handled in
  `view.rs`'s `on_key_down`. Insets have no such stand-in, so
  `android/insets.rs` registers one more native method
  (`applyWindowInsetsNative`) directly on `IrisView`, writing into an
  `Rc<RefCell<Shared>>` a second copy of which lives in
  `AndroidUiState` — the peer id android-view hands back from
  `register_view_peer` is opaque outside that crate, so this is a
  side table keyed on the same id rather than a way to reach the peer
  itself. `MainActivity` wires `setOnApplyWindowInsetsListener`,
  including the API 30+ `ime()` inset specifically (falls back to 0
  below that). Not yet consumed by any widget's layout — `insets()` is
  exposed on `AndroidUiState` but nothing reads it yet, since the tabs
  example has no chrome that needs to avoid the keyboard.
  
  **The IME bridge is implemented and its pass condition holds.**
  `android/ime.rs` implements the full `InputConnection` trait
  (`text_before_cursor`/`after_cursor`/`selected_text`,
  `cursor_caps_mode`, `delete_surrounding_text[_in_code_points]`,
  `set_composing_text`/`_region`, `finish_composing_text`,
  `set_selection`, `begin`/`end_batch_edit`, `send_key_event`,
  `request_cursor_updates`) directly against `TextEdit` — the same
  preedit-replace bookkeeping `default`'s `Ime::Preedit` handling uses
  (`compose_len`, in chars), with new byte<->UTF-16 conversion helpers
  since parley (since I1) is byte-indexed and Java strings are not.
  Two approximations, both commented in place rather than silently
  dropped: `set_composing_region` declines (no separate composing range
  exists to move) and `set_selection`/`delete_surrounding_text_in_code_points`
  collapse to an approximation rather than a real span/code-point
  count. `TextEdit` gained `text()`/`selection_range()`/`caret()`
  getters and `TextEditCtx::delete_byte_range`/`set_cursor_byte`, all
  unconditional (no winit dependency added); `apply_event`/
  `TextInputResult`, which do take a `winit::event::KeyEvent`, are now
  `#[cfg(not(target_os = "android"))]` instead of being ported, since
  android's own `input.rs` calls `TextEdit`'s primitives
  (`backspace`/`delete`/`motion`/`insert`) directly from
  `ndk::event::Keycode` and never needed a winit `KeyEvent` shape.
  
  **Measured on the emulator, 2026-09-05, x86_64 API 26,
  `-feature Vulkan` + SwiftShader per the Vulkan section below.**
  `adb shell dumpsys input_method` after tapping the composer field:
  `mInputShown=true`, `mServedInputConnection` is
  `org.linebender.android.rustview.RustInputConnection` attached to
  `IrisView`. `adb shell input text "hi"` followed by a screenshot
  shows **Gboard's suggestion strip populated with "hi | Hi | HI"** —
  capitalization variants read back out of the real buffer through
  `text_before_cursor`, the same kind of evidence E1 recorded (there:
  "dolor | Dolores | door"). That is the bar this box asks for, met.
  
  **Resolved 2026-09-05: the render gap was the window uniform, never
  the atlas.** `UiRenderNode::new` (`core/src/render/mod.rs`) seeded the
  GPU's `window_buffer` from `WindowUniform::default()` — width=0,
  height=0 — and the only thing that ever corrected it was a later call
  to `UiRenderNode::resize`, renamed `AndroidRenderer::resize` on the
  android side. winit's backend gets away with the same default because
  winit fires an initial `WindowEvent::Resized` before the first frame,
  which `default/mod.rs`'s event loop turns straight into that resize
  call — a real event this project never had to add on purpose, so
  nothing here noticed the node depended on it. android-view has no such
  automatic event: `surface_changed` (`src/android/view.rs:363-388`)
  only calls `self.render.resize(...)`, which is
  `UiRenderState::resize` — the CPU-side *layout* width the widget tree
  lays out against — not `AndroidRenderer::resize`, which is the one
  that writes the GPU uniform. `AndroidRenderer::new` builds a fresh
  `UiRenderNode` with the correct `SurfaceConfiguration` (so the surface
  itself was always the right size, and the clear colour reached it) but
  that node's window buffer was never subsequently written, so it sat at
  `(0, 0)` for the node's entire life. `shader.wgsl`'s `vs_main` divides
  by `window.dim` to reach clip space
  (`let pos = (top_left + uv * size) / window.dim * 2.0 - 1.0;`), so
  every primitive's clip position came out `NaN`/`Inf` and was dropped
  before rasterization on **both** backends — Vulkan and GLES alike,
  exactly the cross-backend symmetry that should have pointed away from
  a GL-specific cause sooner. The layout engine reporting the correct
  widget count and pixel region the whole time is consistent with this:
  that path never touches `window.dim` at all, since it is a separate
  copy of the window size (`UiRenderState`'s own, fed by
  `self.render.resize`) that the CPU-side layout and hit-testing use.
  
  **The GLES `D2`/`D2Array` warning was confirmed a red herring.**
  Reproduced again after the fix, unchanged, on a build forced to
  `Backends::GL` — it fires on every frame regardless, and primitives
  draw correctly on that backend anyway (screenshot below), so it is a
  cosmetic wgpu-hal heuristic notice, not a correctness bug in the atlas
  path. Left as-is; chasing it further is not warranted.
  
  **Fix** (`core/src/render/mod.rs`, `UiRenderNode::new`): seed
  `WindowUniform` from `config.width`/`config.height` — already the
  surface's real size at construction time on both backends — instead
  of `WindowUniform::default()`. This removes the dependency on an
  external resize call entirely (winit's initial `Resized` event still
  fires and still calls `resize()`, now idempotently) rather than
  papering over android-view's missing event with one more call in the
  android-specific path; a future third backend gets a correct window
  buffer from its first frame with no equivalent event of its own to
  remember.
  
  **Verified on the emulator, 2026-09-05, `ai-app-2`'s own AVD, x86_64
  API 26, `-feature Vulkan` + SwiftShader per the Vulkan section.**
  `logcat` after launch: `render(): after update active=39
  root_px=Some(PixelRegion { top_left: (0, 0), bot_right: (1080,
  2219) })`, no wgpu validation warnings on the Vulkan build. Screenshot
  (`/tmp/iris_i2_render.png`) shows the tabs example's coloured spans,
  the red rounded rect and the tab bar all drawn — the milestone this
  section asked for. Rebuilt with `Backends::GL` forced (reverted
  afterwards; the shipped code still requests `Backends::PRIMARY`) and
  reinstalled: same screenshot, same widgets, `AdapterInfo` logged as
  `Android Emulator OpenGL ES Translator (virgl (AMD Radeon RX 7900
  XT...` confirming the real GLES/virgl path, with the `D2`/`D2Array`
  warning present and harmless as above. Text glyphs render with visible
  artifacting on the GLES path specifically (not investigated further —
  out of scope for this box, which is about primitives appearing at
  all, and it does not affect the Vulkan path this app ships behind).
  
  **Not built yet**: anything consuming `insets()`, a real phone
  measurement (only the emulator so far — matches every other Android
  finding in this file), and AccessKit (I4's job, so `ui-trace`
  couldn't be used here; a raw `adb shell input tap`/`input text` stood
  in for driving the UI, which is why this section says "the same bar
  as E1" rather than citing a `ui-trace` transcript).
  
  **Verification.** Host: `cargo fmt --all -- --check`,
  `cargo build --workspace --all-targets`, `cargo clippy --all-targets`,
  `cargo test --workspace` (19 tests) all clean in `iris/`; `iris/run-headless.sh
  tabs --shot` still renders pixel-identically (27266 bytes, byte-for-byte
  unchanged). Android cross-compile: `cargo ndk -t x86_64 -P 26 build`
  and `... clippy` clean for both `iris` (with the android module) and
  `iris/android-app`. Emulator: `emu up` with
  `VK_DRIVER_FILES=.../vk_swiftshader_icd.json` and
  `GPU_HOST_FEATURES="-feature Vulkan -no-snapshot-load -no-snapshot-save"`
  per the Vulkan section; `cd android-app && cargo ndk -t x86_64 -P 26
  -o app/src/main/jniLibs/ build --release && gradle :app:assembleDebug`
  (release native lib per E1's segfault finding, debug Gradle variant --
  the jniLibs contents are what matters, not the Gradle build type);
  `adb install -r app/build/outputs/apk/debug/app-debug.apk`. Emulator
  torn down after verification (`emu down`) per the machine's memory
  rule.
  

• I3 — a virtualised, bottom-anchored list (2026-09-05). Variable-height rows, keyed, composed only while visible, paged in both directions with a "more" sentinel at each end, a scroll anchor that survives rows being inserted above, and "hold the edge nearest the tap" done in the layout pass. Built as iris::widget::List (iris/src/widget/list.rs, its module doc is the design writeup) -- see IRIS.md's 2026-09-05 entry for the public API and the one correctness lesson worth carrying elsewhere (a fill-shaped background cannot be measured at a throwaway oversized region and merely repositioned into place; it has to be placed at its cached real size, or measured-then-redrawn via draw_twice on first appearance).

  **Done**: the widget, 6 unit tests (`cargo test -p iris`, anchor and
  edge-hold logic, all pure -- no GPU/window needed, same harness as
  `layout_tests.rs`), `iris/benches/message_list.rs` rewritten to
  measure the real widget instead of a hand-built `Span`+`Scroll`, two
  new benchmark scenarios ((d) insert-above-anchor, (e)
  expand-a-row-holding-its-edge), and `iris/examples/message_list.rs`
  (800 rows, varied wrapped-text length, one in twelve with an image,
  mouse-wheel scrollable) rendered via `run-headless.sh` and visually
  verified (cropped with a throwaway PNG decoder, since this VM has no
  image tooling -- see the commit for the crop script's shape).
  
  **Numbers (2026-09-05, release, this VM), all flat across N =
  100/1,000/10,000 as required:**
  
      cd iris && ./run-bench.sh list
      (a) first frame:                 ~12.3-12.9ms  draws=80   rewrites=3   moves=0
      (b) scroll, 200 ticks:            4.8-6.5ms    draws=328  rewrites=12  moves=10131  (~0.025-0.033ms/tick)
      (c) input grows, 40 lines:        8.9ms        draws=1846 rewrites=102 moves=1195   (~0.22ms/line)
      (d) insert-above-anchor, 200 pushes: 0.4ms      draws=200  rewrites=0   moves=0      (~0.002ms/push)
      (e) expand-hold, 40 growths:      0.10-0.11ms  draws=119  rewrites=40  moves=15     (~0.003ms/growth)
  
  (d) is the cleanest confirmation: 200 rows prepended one at a time
  while scrolled to the loaded window's start cost 200 draws total (the
  list widget's own redraw each push) and **zero** row draws or moves
  -- none of the prepended rows ever entered the viewport, exactly as
  the anchor-by-slot-index design predicts. (e) similarly stays tiny
  and flat: growing one row 40 times, each preceded by `note_tap` at
  its own edge, costs a total of 15 moves (the rows on the far side of
  the held edge) regardless of how many thousand rows exist elsewhere
  in the list.
  
  **Verification.** `cargo fmt --all -- --check`,
  `cargo build --workspace --all-targets`,
  `cargo clippy --all-targets` (and `--benches --release` separately,
  since benches aren't always covered), `cargo test --workspace` (25
  passed) all clean in `iris/`.
  
  **What remains — the emulator half of the pass condition, blocked on
  the emulator being held by another session during this pass.** The
  condition as written ("800 rows of real transcript text from the
  sandbox scroll without a frame over the Compose baseline in
  `transcript-bench.sh`, measured on the GPU emulator") needs the
  transcript screen actually rebuilt on top of `List` (this box only
  built and measured the widget in isolation, per the task scope) and
  then driven through the real emulator rig. Once that screen exists,
  the exact command is:
  
      cd app && ./transcript-bench.sh -k    # or without -k for a fresh session
      # compare its render report against the iris build's equivalent
  
  This is a genuinely separate step (wiring `List` into an actual
  session screen, i.e. most of I5's work) rather than something this
  box's scope could finish alone -- recorded here rather than left
  silently undone.
  

• I4 — accessibility names via AccessKit, host half done and verified 2026-09-05; the emulator half is the one step left, named at the bottom of this box. Built iris_core::ui::access::AccessTree (iris/core/src/ui/access.rs) -- one flat AccessKit tree, a synthetic Role::Window root with every named widget as a direct child. Deliberately flat rather than mirroring iris's real widget nesting: nothing upstream of a named leaf needs a node, since a screen reader's traversal (and uiautomator's tap-by-name, this box's own pass condition) works from each node's on-screen bounds, not from tree structure -- and mirroring the real tree would rebuild intermediate nodes on every resize of any container above a named widget, which is most frames.

  **Modular the way input's sense registry is.** `Widgets` gained one
  `HashSet<WidgetId>` (`named`), populated only by `.label()`/
  `set_label` and drained by `free_next` (the same removal path a
  freed id already went through -- no second bookkeeping call added
  anywhere). `AccessTree::update` walks `widgets.named()` directly,
  never the full widget arena, so a widget nobody named costs this
  subsystem nothing -- not a visit, not a branch. Roles come from a
  new `Widget::access_role(&self) -> accesskit::Role` trait method,
  default `Unknown`; the one override so far is `TextEdit` ->
  `TextInput`/`MultilineTextInput` by `EditMode`. Bounds come from
  `UiRenderState::window_region`, which sits on `resolved_region`'s
  move-chain walk -- so a widget moved via `Offset`/`Scroll` (never
  redrawn from scratch) still reports where it actually ended up; see
  `bounds_follow_a_moved_widget_and_updates_stay_incremental` below.
  
  **Incremental, not per-frame.** `AccessTree` keeps the last
  `HashMap<WidgetId, Entry>` (name, role, bounds) it sent and only
  returns a new `TreeUpdate` -- and only then bumps its `rebuilds`
  counter, `take_rebuilds()`'s the AccessKit twin of
  `UiRenderState::take_counters` -- when that set actually differs.
  Confirmed by `bounds_follow_a_moved_widget_and_updates_stay_incremental`
  (`iris/src/access_tests.rs`): 1 rebuild on the first draw, 0 across an
  unchanged frame, 1 more after a real move, regardless of how many
  other widgets are on screen.
  
  **`SlotId::as_u64`** (`core/src/util/slot.rs`) encodes a `WidgetId`
  into accesskit's flat `NodeId(u64)`, offset by one so a real widget
  never collides with the reserved window node (`NodeId(0)`).
  
  **Pushed through two backends, each behind an inert action/activation
  handler** -- see below for why inert is correct, not incomplete.
  `default/access.rs` (winit): `accesskit_winit::Adapter`, built in
  `DefaultApp::new` with the window created hidden
  (`with_visible(false)`) and shown only after the adapter exists,
  which is what that constructor requires. `process_event` runs on
  every `WindowEvent`; `update_if_active` runs once per
  `RedrawRequested`, after `render.update()` so bounds reflect the
  frame just drawn. `android/access.rs` (android-view):
  `accesskit_android::Adapter` on `AndroidUiState`, `IrisViewPeer` now
  implements `AccessibilityNodeProvider`
  (`create_accessibility_node_info`/`find_focus`/`perform_action`), and
  `render()` (now taking `&mut CallbackCtx`, needed for the JNI handle
  any `raise` requires) pushes the same `AccessTree::update` after
  every draw.
  
  **Why the `ActionHandler`s are empty, not a placeholder for later
  work**: AGENTS.md's own "Driving the UI" section says it plainly --
  `ui-trace record --do "tap 'Save'"` resolves the label against the
  screen and performs a **real touch at that node's bounds**, the same
  as a person's finger. It does not call into AccessKit's action
  system at all. So once `AccessTree` reports correct bounds, the
  ordinary pointer path (already built, already tested) is what
  answers the tap -- there is nothing for `do_action` to do for this
  pass condition specifically. A future real screen reader's own
  double-tap-to-activate gesture works the same way, for the same
  reason. If iris ever needs to answer an AccessKit `Action::Click`
  injected without a matching touch (e.g. a switch-access scanner),
  that is new scope, not a gap in this box.
  
  **E1's abort mitigation, carried.** `android/access.rs`'s
  `raise_if_enabled` is the one place `QueuedEvents::raise` may be
  called: it asks `AccessibilityManager.isEnabled()` (a `getSystemService`
  JNI call, since android-view has no ready-made wrapper) immediately
  before every `raise` and drops the events instead when the answer is
  no. Every call site (`render`'s per-frame push, `perform_action`)
  goes through it, and each pushes it as a *deferred* callback exactly
  like android-view's own demo, so it runs after the current JNI
  callback has released whatever it's holding -- `raise`'s own
  documented requirement. Not independently re-triggered on this
  pass (that needs the emulator, see below); the mitigation is coded
  to the exact mechanism E1 diagnosed (`sendAccessibilityEvent`
  throwing when accessibility is off) rather than to the symptom, so
  there is no reason to expect it behaves differently here than it did
  there.
  
  **Verified, 2026-09-05, host only.**
  `cargo fmt --all -- --check`, `cargo build --workspace --all-targets`,
  `cargo clippy --all-targets` (both plain and `--all-targets`) clean;
  `cargo test --workspace` -- 28 tests in `iris/`, three of them new
  (`access_tests::a_named_widget_reaches_the_tree_with_its_role_and_bounds`,
  `::a_widget_with_no_label_never_reaches_the_tree`,
  `::bounds_follow_a_moved_widget_and_updates_stay_incremental`).
  `cd iris/android-app && cargo ndk -t x86_64 -P 26 build` and
  `... clippy` clean for both `iris` (with the android module) and
  `iris-android-app`, same shape as I2/I3's checks.
  `iris/run-headless.sh tabs --shot /tmp/iris_i4_tabs.png --seconds 4`
  still renders -- **27266 bytes, byte-for-byte identical to I2's own
  post-fix screenshot** -- confirming the hidden-window-then-adapter
  change to `DefaultApp::new` cost nothing visible. `tabs-ui`'s five
  switch buttons (`tabs-ui/src/lib.rs`) now carry `.label()`s matching
  their on-screen text ("pad", "span", "image span", "text layout",
  "text edit scroll") -- both so the desktop run above exercises a
  non-empty tree and so the emulator step below has real names to tap.
  Not independently checked on this pass: whether `accesskit_winit`'s
  Linux path (AT-SPI, via `accesskit_unix`) actually reaches a real
  assistive-technology client on this VM's headless sway -- there is
  no AT-SPI registry running here, so `default/access.rs`'s handlers
  are exercised as inert code paths (built, called, no panic) rather
  than confirmed end-to-end the way the emulator step below confirms
  the Android path.
  
  **What remains -- the one check that needs the emulator, held by
  another session during this pass.** `iris-android-app`'s tabs screen
  has never been driven by `ui-trace` for real; everything above is
  "builds, runs, produces the right data" on the host. Once the
  emulator is free:
  
      cd iris/android-app && cargo ndk -t x86_64 -P 26 -o app/src/main/jniLibs/ build --release && gradle :app:assembleDebug
      adb install -r app/build/outputs/apk/debug/app-debug.apk
      # launch iris-android-app on the emulator, then:
      ui-trace record --do "tap 'pad'"
      ui-trace record --do "tap 'span'"
      ui-trace record --do "tap 'image span'"
      ui-trace record --do "tap 'text layout'"
      ui-trace record --do "tap 'text edit scroll'"
  
  Pass condition: each tap resolves (uiautomator finds a node with
  that exact label) and switches `main`'s visible pane the way a
  direct touch on that button already does -- i.e. `bench-lib.sh`'s
  tap-by-name mechanism, unmodified, driving the iris screen instead
  of the Compose one. Also worth checking while the emulator is up,
  since E1 found it exactly this way: run a second `ui-trace record`
  immediately after the first (attach, detach, attach again) and
  confirm the process is still alive afterward -- the detach-abort
  this box's mitigation exists for.
  

• [~] I5 — the transcript screen in iris (2026-09-05). The widget-tree half is built, tested and screenshotted; the emulator half (real device numbers against the Compose baseline) is not -- ticked partial rather than done, see "What remains" at the end of this box.

  **Where it lives.** `iris/transcript-ui/` (new workspace member,
  `[lib]`), the same shape as `iris/tabs-ui`: generic over `Rsc:
  HasEvents` + `Rsc::State: FocusHost` so the same `build()` can run
  under winit (`transcript-ui/examples/transcript.rs`) or an
  android-view cdylib later. Depends on `client-core`/`event-model` by
  path (real code, matching E2's precedent) and `pulldown-cmark`
  (0.13.4, current stable). Four modules: `markdown.rs` (CommonMark ->
  plain text + `Vec<SpanStyle>`), `row.rs` (one `iris::widget::List`
  row per folded `TranscriptRow`), `selection.rs` (cross-row
  selection), `composer.rs` (the growing input field). `lib.rs`'s own
  module doc has the screen's shape and the one gap it documents up
  front (below).
  
  **New iris API, added in this box and recorded in `IRIS.md`:
  `SpanStyle`, per-range text styling.** This is the actual answer to
  RUST.md's E2 finding against Masonry ("rich inline text -- block-level
  yes, inline no, and both for the same reason":
  `masonry/src/widgets/text_area.rs:43-44`'s `TextArea::edit_styles()`
  returns one `StyleSet` for the whole editor, with `// TODO:
  RichTextInput` beside it). `core/src/primitive/text.rs`'s
  `TextBuffer` gained `spans: Vec<SpanStyle>` and `set_spans`;
  `SpanStyle{range, color, family, font_size, bold, italic,
  underline}` pushes into parley's `RangedBuilder` via `.push(property,
  range)` instead of only `.push_default(...)`, so one `TextEdit` can
  carry a heading's bigger bold font, an inline-code span's monospace
  colour, a link's colour+underline and an ordinary paragraph's base
  style all in the *same* wrapped, selectable buffer.
  `core/src/render/atlas.rs`'s `PlacedGlyph` gained a `color: UiColor`
  field (read from parley's own per-run `Style::brush`,
  `core/src/primitive/text.rs`'s `TextData::place`) and
  `core/src/ui/painter.rs`'s `glyphs()` now colours each glyph from
  that field instead of one colour for the whole `RenderedText` --
  the change that actually makes a span's colour reach the screen.
  **Real bug found and fixed while wiring this in**: `TextBuilder`'s
  `.spans(...)` was only threaded through `TextOutput::run` (the
  read-only `Text` widget), not the sibling `TextEditOutput::run` (the
  `TextEdit` every transcript row actually uses) -- a "rule that
  governs a set belongs to the set, not one member" miss, per
  CODE_RULES.md; found because `run-headless.sh`'s screenshot showed
  *no* styling at all despite `markdown.rs`'s own unit tests passing
  (they only check the string/range logic, not the render path -- see
  `iris/src/widget/text/build.rs`'s `TextEditOutput::run`, now fixed).
  
  **The seven behaviours, each shown or given a sourced reason, same
  structure as E2's own accounting:**
  
  1. **Selection spanning rows -- shown, with a scoped shortcut
     recorded rather than hidden.** `selection.rs`'s `Selection`
     coordinates each visible row's own `TextEditCtx::select`/
     `select_all`/`deselect` (already built for one field, I2) from a
     single drag that crosses row boundaries: rows between the anchor
     and the pointer get `select_all()`, the row under the pointer gets
     a true partial selection from whichever edge faces the anchor,
     and `selected_text()` concatenates the result in row order. The
     one shortcut: the *anchor* row is selected in full once the drag
     leaves it, rather than "from the click point to its far edge",
     because that needs the row's own laid-out size and
     `TextEditCtx`'s `layout()` helper is private
     (`iris/src/widget/text/edit.rs`) -- see `selection.rs`'s module
     doc. Pure range-membership logic (`in_range`, mirroring
     `begin`/`extend`'s row-selection arithmetic) is unit-tested
     without any render harness; the widget-level wiring is not
     independently screenshotted this pass (would need a synthetic
     drag injected into the winit example -- not attempted, time).
  2. **Rich inline text -- shown, genuinely inline this time.**
     `markdown::render_markdown` folds one row's whole markdown (not
     one block at a time) into one string plus spans, so a heading, a
     **bold** word, *italic* text, `inline code`, and a
     [link](url) inside the same paragraph render in one `TextEdit`
     that still wraps and selects as a single buffer --
     screenshotted, see below. Deliberately not attempted, each
     recorded at the point it would have gone in `markdown.rs`'s own
     doc: a background chip behind inline code (needs glyph-run
     geometry `TextEdit`-internal and not exposed, the same primitive
     `TextEdit::draw`'s selection highlight uses,
     `iris/src/widget/text/edit.rs:99`), a tappable link (same missing
     primitive), a real table layout, and per-token syntax colour
     inside a fence.
  3. **Bottom-anchored virtualised list, hold-the-edge on expand --
     shown**, reusing I3's `List` unmodified. A `TranscriptRow::Tools`
     row collapses to "N tool calls" and expands to every call's own
     tool/input/output on tap; `row.rs`'s click handler calls
     `List::extent(key)` to convert the tap's row-local position into
     the viewport-relative position `List::note_tap` wants, exactly
     the two-step contract `list.rs`'s module doc describes for
     `holdTopEdge`. Not independently screenshotted mid-expand this
     pass (no input-injection into the desktop example was built) --
     the mechanism is the same one I3 already benchmarked
     (`expand-hold`, flat at 0.10-0.11ms across N), applied to real
     content instead of a synthetic row.
  4. **The soft keyboard -- inherited from I2, not re-investigated.**
     The composer (`composer.rs`) is an ordinary `TextEdit` with the
     same `InputConnection` bridge I2 built and measured (Gboard
     suggestions over real buffer content); nothing new to add here,
     and no Android shell exists yet for this screen specifically to
     re-verify it against (see "What remains").
  5. **Platform integration -- out of scope by design**, same as E2:
     E3's list, not this box's.
  6. **Accessibility names -- shown for the composer, not yet for
     rows.** The composer field carries `.label("Message")` (I4). Rows
     do not yet carry per-row labels (a row's own text *is* its
     accessible content via `TextEdit`'s `access_role`, I4, but
     nothing calls `.label()` on it, so `Widgets::named()` does not
     include it) -- a small, real gap, recorded as an IRIS_TODO.md
     item rather than silently left, since AGENTS.md's bench scripts
     depend on exactly this for driving a screen by name.
  7. **Measurable frames / the render-number pass condition -- the
     gesture-conflict half is now fixed (2026-09-05); the emulator
     half is still not attempted, and unlike E2 that's not an absent
     gesture path.** `List` demonstrably scrolls (I3's flat
     draws/moves, programmatic `scroll()`) and mouse-wheel scrolling
     is wired here (`lib.rs`'s `CursorSense::Scroll` on `list`). What
     was *not* reachable at first was a **touch-drag pan starting on a
     row's own text**: `row.rs` registered `CursorSense::
     click_or_drag()` on each row's `TextEdit` for selection, and
     `TextEdit::draw` calls `painter.child_layer()`
     (`iris/src/widget/text/edit.rs:87`), so `core/src/sense.rs`'s
     `run_sensors` (which stops at the first layer, checked
     innermost-first, that consumed the gesture) gave that row first
     refusal on *every* frame it was pressed, not just the frame the
     press started -- a row's drag-select won the same gesture a
     list-level pan would want. This is a genuine, diagnosed
     architecture gap this box's *own* two features created by both
     wanting the same gesture -- not a missing primitive the way
     Masonry's absent `on_pointer_event` drag handling was.
  
     **Gap closed, 2026-09-05, same day.** `iris::sense::DragArbiter`
     (`iris/src/sense.rs`, new public type, recorded in `IRIS.md`) is
     one small state machine, one instance per gesture surface (a
     whole list, not per row), driven with a caller-supplied `Instant`
     so it needs no render harness to test. It decides the way
     Android itself does, recorded in `DECISIONS.md`: an ordinary
     vertical drag pans immediately; a stationary press held
     `LONG_PRESS` (500ms) starts a selection, which any further drag
     then extends; a horizontal drag while something is already
     selected extends it immediately, skipping the wait.
     `transcript-ui/src/selection.rs`'s new `Selection::drag` is the
     one place every row's `CursorSense::click_or_drag() |
     CursorSense::unclick()` handler now goes through (`row.rs`,
     `build_text_row`), replacing the direct `begin`/`extend` calls
     each row used to make on its own -- one arbiter shared across
     every row is what keeps the decision consistent as a drag
     crosses row boundaries, per `DragArbiter`'s own doc. `Pan(dy)`
     calls the list's own `List::scroll` (the same method I3's
     mouse-wheel handler and its own benchmark already use), so this
     is not a second scroll mechanism. 8 new unit tests in
     `iris/src/sense.rs`'s `drag_arbiter_tests` (vertical drag pans
     immediately and keeps panning by per-frame delta; small jitter
     under `DRAG_SLOP` stays undecided; a held press starts a
     selection after `LONG_PRESS` and further drag extends it, even
     vertical drag, once selecting; a horizontal drag with nothing yet
     selected stays undecided rather than guessing; a horizontal drag
     with something already selected extends immediately; a vertical
     drag still pans even with a prior selection; release resets to
     idle). Verification: `cargo fmt --all -- --check`, `cargo clippy
     --workspace --all-targets` (zero warnings), `cargo test
     --workspace` (28 pre-existing + 9 `transcript-ui` + **8 new**
     `drag_arbiter_tests`, all passing), `cargo ndk -t x86_64 -P 26
     build/clippy` for both `-p iris` and `-p transcript-ui --lib`
     (clean), and `run-headless.sh transcript --shot ... -- -p
     transcript-ui` -- byte-identical to this box's original
     screenshot (38578 bytes, `cmp` confirms identical), confirming no
     visual regression from the rewiring. **What this did not
     attempt**: the emulator-side confirmation (a real touch swipe
     over a row's text panning on-device) -- that still needs I5's own
     Android integration, the one item named just above and in "What
     remains" below; this pass only had the winit/host-side gesture
     path to drive, since no cdylib exists yet for this screen.
  
  **Verification, exact commands and results (2026-09-05, this VM):**
  
  - `cargo fmt --all -- --check`: clean.
  - `cargo build --workspace --all-targets`: clean, all six workspace
    members (`iris`, `iris-core`, `iris-macro`, `tabs-ui`,
    `transcript-ui`, plus the excluded `android-app`).
  - `cargo clippy --all-targets` and `cargo clippy -p transcript-ui
    --all-targets`: zero warnings.
  - `cargo test --workspace`: 28 tests in `iris`/`iris-core` (all
    pre-existing, unaffected) + **9 new in `transcript-ui`** -- 5 pure
    markdown tests (`bold_and_italic_produce_spans_over_the_right_range`,
    `heading_gets_a_bigger_font_size_span`,
    `link_is_styled_and_keeps_its_visible_text`,
    `fenced_code_block_is_monospaced`, a plain-text baseline) and 4
    selection tests (forward/backward/single-row range arithmetic,
    plus `unregister_forgets_the_row_and_clears_a_matching_anchor`
    against a real minimal `TextEdit` in the arena, no window needed --
    same harness style as `list.rs`'s own tests).
  - `cargo ndk -t x86_64 -P 26 build -p transcript-ui` and `... clippy
    -p transcript-ui --lib`: clean (`--lib` only -- the example uses
    `iris::default`, winit-only by design, same as `iris/examples/
    tabs`'s own example never having an Android build of itself; the
    Android-facing entry point is a separate cdylib, not built this
    pass, see below). `cargo ndk ... build -p iris` / `clippy -p iris`
    also re-checked clean, since this box touched `iris-core`'s text
    pipeline.
  - `run-headless.sh transcript --shot ... -- -p transcript-ui`:
    renders. Cropped for legibility (this VM has no image viewer --
    see I3's own note on the same limitation and the throwaway crop
    tool used here, not committed): a full conversation with a
    **bold** word, *italic* text, `inline code` in its own colour, a
    `# Sure` heading rendered visibly larger and bold, a coloured link,
    a monospaced fenced code block, a collapsed "▸ 3 tool calls" row,
    and the composer bar at the bottom -- every one of E2's markdown
    screenshot's features, now inline within single paragraphs rather
    than block-per-widget. Screenshots at `/tmp/iris_i5_transcript2.png`
    (full) and crops there, not committed per the standing rule against
    screenshots of real content leaving this repo -- these are
    synthetic rows, but the rule is kept uniform regardless.
  
  **What remains, named rather than silently dropped (also in
  IRIS_TODO.md, dated 2026-09-05):**
  
  - **The emulator half of the pass condition was not attempted.**
    `emu list` shows `emulator-5554` (AVD `ai-app`, a different
    checkout) held by another session during this pass, but even with
    a free emulator this needs real Android integration that does not
    exist yet for this screen: a cdylib + Gradle shell the way
    `iris-android-app` wraps `tabs-ui` (I2), real
    `client-core::ApiClient`/`event_stream::follow_session_events`
    wiring against `app/ui-sandbox.sh` with `--delay` (this crate
    deliberately does not fetch anything itself, see `lib.rs`'s doc),
    and then `transcript-bench.sh`'s gesture compared against the
    Compose baseline. That is real, multi-part follow-on work in its
    own right -- closer in size to E2/E3 than to "run one more
    script" -- not something this pass's remaining time could
    responsibly rush and still report honestly.
  - **Row-level accessibility names** -- behaviour 6 above.
  - **A tappable link and a code-span background chip** -- behaviour 2.
  - **`Selection`'s anchor-row shortcut** -- behaviour 1.
  - **No syntax highlighting inside a fenced code block** -- `markdown.rs`
    notes `client_core::highlight` exists and could feed this.
  - **`row.rs`'s tool-row expand and `selection.rs`'s cross-row drag
    are not independently screenshotted/driven** -- covered by reading
    and by the primitives they reuse (I3's `List` tests, this box's
    own unit tests), not by a dedicated repro this pass.
  
  **Net for the recommendation.** Item 3 ("decide when the transcript
  screen exists in both, from the measurements") still cannot be
  decided by a number -- E2 could not produce one for Masonry, and I5
  has not yet produced one for iris either, for an unrelated reason
  (no Android harness built yet, not an absent capability). What *can*
  be said structurally, updating E2's own conclusion: iris now also
  demonstrates the two things E2 found Masonry structurally unable to
  do at all -- cross-row selection and true per-span inline rich text
  inside one wrapped, selectable buffer -- neither of which exists
  anywhere in `masonry`/`masonry_core`/`xilem` today (E2's own
  `grep -rln` finding). That is a second structural point in iris's
  favour, alongside I2's working touch-scroll-vs-Masonry's-absent one,
  still short of the render-number comparison the recommendation
  ultimately wants.
  

For the next agent

What to do when you pick this up, in order, so nothing here has to be re-derived:

1. Read this file, then AGENTS.md and PLAN.md. The rules there (measure, do not read; fix the rig before accepting its limits; the emulator is this checkout's own) all apply.
2. Work on the rustify branch of this clone (ai-app-2), not on main and not in ai-app. Nothing on this branch is production until Iris says so. Commit and push as you go.
3. Take the next unchecked box above, in order. E1 has proved android-view on this emulator, so the E-steps and the I-steps can now proceed in parallel in separate sessions; see "Where things stand" at the top for which is next.
4. Every step ends with its measurement written into this file beside the box, and the box ticked or the reason it could not be written in its place. A step that is blocked says by what, not "later". Write it as you go rather than at the end — see "Keep this file current as you work".
5. Run the existing rigs rather than inventing new ones: ui-sandbox.sh for a server with fixtures, transcript-bench.sh for the scroll baseline, ui-trace for anything positional, emu up for the emulator, iris/run-headless.sh EXAMPLE --shot PNG for an iris example on this displayless machine, and rigs/gpu-probe to ask a device (this VM, the emulator, or a real phone over adb push) what wgpu features and limits it actually has before building anything on the assumption it does. The Vulkan section below says how to get a Vulkan path in the emulator when a wgpu backend needs one.
6. Bound anything heavy at the moment you start it. An emulator or a long build gets a deadline — timeout, or a watchdog scoped to the pid you just started — rather than a plan to stop it later. Scope it to that pid: a watchdog written as sleep N; emu down fired into a later experiment here and made a working Vulkan build look like a crash. And stop the emulator when the work needing it is done rather than between tasks.
7. Decisions belong here with a date and what was rejected, the way PLAN.md does it. Do not put design into commit messages alone.

Vulkan in the emulator (measured 2026-09-04)

Settled 2026-09-04: the guest gets Vulkan from SwiftShader, and the missing step was a cold boot. -feature Vulkan plus VK_DRIVER_FILES=$HOME/Android/Sdk/emulator/lib64/vulkan/vk_swiftshader_icd.json gets the host side to select SwiftShader, but the guest keeps reporting zero devices until -no-snapshot-load is added, because it boots from a snapshot saved under the previous GPU config — -no-snapshot-save is worth adding too, so the Vulkan-configured snapshot does not then break the next ordinary boot. With that, cmd gpu vkjson reports SwiftShader Subzero and wgpu takes its Vulkan path (E1). EMU_GPU=software in emulator-tools gets the same guest Vulkan with no GPU use at all, for work where the emulator's frame rate is not what is being measured.

The rest of this section stands as the record of why host Vulkan is not available. A wgpu app in this emulator was going to get GLES only, because host Vulkan is switched off in emulator-tools. Retried on Mesa 26.1.7: Venus still fails the same way — gfxstream picks externalMemoryMode: OpaqueFd, probes VK_FORMAT_R8G8B8A8_UNORM for an exportable colour buffer, and Venus says the format is unsupported (Failed to find memory type for ColorBuffers, fatal before adb sees the device). Venus does advertise VK_KHR_external_memory_fd and VK_EXT_external_memory_dma_buf, so the gap is specifically opaque-fd image export. gfxstream has a string-valued VulkanExternalMemoryMode setting ("overrides what would otherwise be determined automatically"), but -feature Name=Value is rejected as a bad feature name, and the only mode words compiled into this emulator's libgfxstream_backend.so (37.1.11) are OpaqueFd, Metal and none — there is no dma-buf mode in this build to switch to. So Venus is blocked by the emulator, not by Mesa; retry when the emulator package updates, since upstream gfxstream does have dma-buf external memory.

What does work: pointing the emulator's Vulkan loader at the software ICDs the emulator ships itself, with the feature enabled:

VK_DRIVER_FILES=$HOME/Android/Sdk/emulator/lib64/vulkan/vk_swiftshader_icd.json \
GPU_HOST_FEATURES="-feature Vulkan" emu up

The guest then reports Vulkan 1.3 (cmd gpu vkjson, SwiftShader Subzero) while GLES still runs on the real GPU through virgl — so a Vello/wgpu app can take its real Vulkan path here, with compute shaders, CPU-rasterised. That is enough to test correctness of the Vulkan path in the emulator; GPU performance of it is a phone measurement either way, exactly as MACHINE.md already says about frame times. lavapipe (lvp_icd.json, the other ICD the emulator ships) selected llvmpipe and booted, then the emulator died right after loading the default_boot snapshot with nothing in the log; a snapshot saved under a different Vulkan device is the suspect, and -no-snapshot-load is the untested next step. SwiftShader is the one that works today. EMU_GPU=software is now in emulator-tools (agreed with the ai-app session and with Iris, default unchanged, since -gpu host was measured and the Compose scroll benchmarks depend on it). The cold-boot flags are not a knob there: that wants snapshot invalidation as well, which is a bigger design question in shared tooling.

Things a Rust app changes elsewhere

• wg-app-link's :link (pinned TLS, enrollment store, QR activity) is Kotlin shared with Dev Updater. The certificate code already exists on the Rust side of the submodule; the pinned-CA build step (generatePinnedCert) becomes a build.rs reading the same path. The QR scanner stays a Kotlin activity, since the camera is a platform feature.
• Tooling becomes cargo for everything but packaging: cargo test, clippy, fmt cover the whole client, which is the motivation. Gradle remains for the APK, signing (~/.config/ai-app/release.jks) and Dev Updater's build modes; build-apk.sh would call cargo ndk first.
• The bench scripts (ui-trace by accessibility label) keep working only if the framework exposes names through AccessKit on Android; that is part of E2's pass condition, not a nicety.
• Icons stay Nerd Font glyphs from the committed subset; Parley/Fontique loads a font file directly, so build-icon-font.sh is unchanged.

Sources

• iced: repo, 0.14 release, Android thread, markdown selection request
• Linebender: 2026 Q1 report, xilem, parley, vello, vello_hybrid
• android-view: repo; android-activity PR #214
• winit Android IME: #1823, #2766, #2305
• egui on Android: discussion #2053
• Slint: Android guide, 1.15 release, licensing, rich text #1325, markdown #6684
• Makepad: repo, makepad-widgets, Robrix, Robrix releases
• AccessKit: releases
• Build tools: cargo-ndk, cargo-apk, rust-mobile
• uniffi: repo, KMP bindings fork
• GPUI mobile: gpui-mobile
• The earlier Dioxus spike's findings on wgpu/Vulkan in this emulator: ~/repos/tdep-survey/app-dioxus/README.md