# Handoff Where the work in flight stands. The settled layout design, the vocabulary and the measurement method are in `docs/LAYOUT.md`; what the review of #19 found is in `docs/LAYOUT_LOG.md`. ## The Iris layout repair is submitted **Iris PR #19** (`layout/one-ask`) replaces closed #18. The tip is `6c84b6f`, and past the reviewed `cadfba0` it is three rounds: - **The repair.** `add6774` fixes collapsed-share placement, retained mask ownership and a redraw-on-reparent defect; `84dad21` removes repeated work in the test harness. - **The vocabulary and the container API**, `5642f20` through `58ce74d`. What they settled is described as design in `docs/LAYOUT.md` under "Three names, and the one argument that says them" -- region, placement and rel_base, and the single `impl Into` argument that replaced `Place`, `Part`, `widget_within` and the separate rel-base argument. **Bryan is still refining this**, so treat the API as current rather than frozen. - **Named operations and `Index`**, `55df32a` and `2807a92`, settled with Bryan on 2026-09-19. A description is built by chaining off the value that says it (`UiSpan::shifted_desc`, `Len::as_desc`), never by a constructor naming the type; `on` is reserved for events, so the lift is `PlaceDescAxis::on_axis`. Arithmetic that needed a comment became a name: `UiSpan::place`, `LayoutLen::without_leftover`/`is_px`/`is_only_leftover`/ `declared`, `Holds::covers`. `LayoutHolds` became `AxisHolds` on `x`/`y`, every pair got `Index` through `impl_axis_index!`, and the bare `[Option; 2]` became `Declared` of `Option`. - **A sweep over the logic the clearer methods exposed**, `8d2b7a5` and `6c84b6f`. A `Span` carried `start` as a third accumulator when it was always `fixed` and `taken` read together, so both ends of a slot are now read where they are used. A `Scroll`'s draw writes `amt` and `snap_end`, so warm and cold agree only because re-clamping is idempotent; the seed scans build scrolls and never scroll one, so a test now pins it. The core design remains sound. Round-to-nearest is still unchanged. Two checkouts share one Git storage: `/home/bob/repos/iris` is the active `layout/one-ask` worktree, and `ai-app-2/iris` stays on `main` at the app's `32f6ad8` pin until the integration below is ready. ### How each round was checked Format, workspace clippy under `-D warnings` with and without `layout-diagnostics`, the workspace tests both ways, and the three prescribed seed scans -- 400 at depth 5, 1,000 at depth 6, 2,000 at depth 4. The gate that matters for anything shaped like a rename or a refactor is the **cold dump**: `layout_dump` over 400 depth-5 trees is 34,492 boxes, and the compiler cannot catch two same-typed values being swapped. The repair moved 650 of those boxes, all from the collapsed-share correction. Every commit since has been byte-identical to `84dad21`, including the whole API rewrite and the naming work above. ## What is next, in order 1. **Bryan's review of #19.** Fixes are themselves unreviewed code: repeat `pre-submit-review` over each round's changes, and re-run the three fuzzers and the dump diff for edits to `Span`, `Painter`, or `render_state`. The ordinary oracle does not replace absolute geometry and retained-primitive expectations. 2. **Integrate the app's Iris capabilities before changing its pin.** `32f6ad8` has 45 commits not reachable from the review branch; shared UI ownership, richer masks, Android support, and app-side performance work must survive the integration. The app then absorbs the branch's vocabulary and container API, all of it already upstream: `rest` -> `leftover`, `SizeRule` beside widgets, alignment properties, the removal of `OrthoSize`, region/placement/rel_base, and `PlaceDesc`. 3. **Round-to-nearest**, CPU and shader together as one verified change. Bryan approved it on 2026-09-17 and neither half has landed; the derivation, the form to use and what to re-check are in `docs/LAYOUT.md` under "Rendering the grid (pending)". Wanted but not started, recorded in `iris/TODO`: transforms on a move entry, so a whole subtree scales or rotates with one buffer write and no redraw. Compose-style stretch at the end of a scroll area is the use that prompted it. A move entry only translates today, and composing through one scales the `rel` part while `px` passes through untouched, so fixed-size content and glyphs do not follow a shortened entry. ## Smaller layout items, none urgent - Nested spans pass `leftover` weight up, so three leftover children in one inner span beside one in another get three quarters to one quarter. No other layout system does that; confirm it is wanted. - A span can overflow itself without bound, so boxes of negative length reach children and nothing states what a widget may assume about one. - `Fixed::div` by zero answers `MIN`/`MAX` while `ratio` answers `ZERO`; both are caller bugs under `debug_assert`, but the fallbacks differ. - `docs/LAYOUT.md` §4, §5 and the density section name `Painter::place`, `Painter::region()`, `SetSize`, `desired_width`, `apply_rest`, `Len::dp`, `Aligned` and `MaxSize`, none of which exist. Do not restore `OnResize::Translate` or `OrthoSize`. - `LazySpan`, then `SizeRule::{Min, Max, Clamp}`. A cap may not contain `leftover`; whether `Max` narrows the child's drawing box is a product decision. - `Scroll` taking a direction rather than one axis. Other product work is in `docs/PLAN.md` and the focused documents it links. Do not mix it into the Iris layout branch.