DECISIONS.md, RUST.md: Iris decided iris over Masonry, 2026-09-05

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

docs/DECISIONS.md

@@ -65,7 +65,17 @@ marked **DEFERRED** are ones the agent chose not to decide alone.
 - **Order of remaining work, updated 2026-09-05**: the two in-flight
   pieces and I5's Android integration are all done; next is giving iris
   its own frame-timing report so item 3 below can be decided by a number.
-- **DEFERRED — whether to commit to iris over Masonry for `ai-app`.**
+- **DECIDED by Iris, 2026-09-05: iris is the app's framework; Masonry was
+  the calibration.** Her words: "I think iris definitely makes more sense
+  based on the limitations we've found." The limitations: Masonry has no
+  touch scroll on Android (E2), no per-span rich text and no cross-row
+  selection on the pinned commit (E2), and its keyboard bridge is a TODO
+  (E1); iris carries the same screen under the Compose baseline on the
+  host GPU (p50 15.0 ms against Compose's 20.0 ms, RUST.md's I5 box). What
+  follows: the E-steps are closed as calibration, and the port proceeds
+  on iris — screens, the shell (E3/E5), and `client-core` underneath.
+  The item below is kept as the record of what she decided from.
+- **Was DEFERRED — whether to commit to iris over Masonry for `ai-app`.**
   Updated 2026-09-05 with the clean comparison the recommendation wanted:
   same sandbox session content, same emulator, `EMU_GPU=software`, one
   session. Headline numbers (RUST.md's I5 box, "Clean scroll comparison,