diff --git a/RUST.md b/RUST.md
index 8193a80..eb47386 100644
--- a/RUST.md
+++ b/RUST.md
@@ -648,17 +648,62 @@ step measured.
       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 — the text stack decision.** iris uses cosmic-text; the
-      transcript needs rich inline spans (links, code chips, colour),
-      selection across many widgets with the platform's handles on the
-      phone, and an editor the IME can drive (composition regions, not
-      just committed characters). Compare cosmic-text and Parley against
-      exactly those three, in iris, on a real transcript's text. Parley
-      is the expectation because android-view's IME bridge and AccessKit's
-      text properties are written against it; measure rather than assume.
-      Pass: a written decision here with what each was tried on, and the
-      TODO's "text resizing per frame is really slow" measured and either
-      fixed or explained.
+- [x] **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.**
+
 - [ ] **I2 — iris on android-view.** An `android-view` surface as a second
       backend beside winit: `wgpu` on the view's surface (GLES here, see
       the Vulkan section; Vulkan on the phone), touch as pointer events,