docs: the defect pass's findings -- RUST.md boxes, IRIS_TODO ticks, DECISIONS and IRIS entries

docs/IRIS_TODO.md

@@ -282,7 +282,25 @@ agent ticks it here with the evidence.
   since only she can say whether it *feels* like a fling now; the
   emulator's screenshot timing could not always catch the tail of a
   fast-settling one visually (same caveat noted in RUST.md).
-- [ ] **"Text still disappears if I leave and come back to the app."**
+- [~] **"Text still disappears if I leave and come back to the app."**
+  **Instrumented 2026-09-06 so the phone can answer it**, since no
+  emulator here has a Vulkan adapter. `iris/src/android/view.rs` now logs
+  one `log::info!` line per surface event with the glyph/atlas counts:
+  `iris surface: surface_destroyed, tearing the renderer down
+  (glyphs_cached=387 atlas_pages=1)`, `iris surface: surface_changed
+  1080x2424 already_live=false glyphs_cached=387 atlas_pages=1`, `iris
+  surface: new renderer built (Gl), clearing glyph atlas: glyphs=387
+  pages=1`, plus `iris insets: ... window=(1080, 2424)` on every insets
+  change. That is the emulator's own healthy app-switch cycle, verified
+  this pass (home, reopen, screenshot: all text intact,
+  `/tmp/appswitch.png`). **The one line to look for on the phone is
+  `already_live=`**: `true` on the return from backgrounding would mean
+  the surface came back *without* a `surface_destroyed`, so
+  `surface_changed` reconfigured a renderer whose Vulkan swapchain and
+  atlas textures belong to a window that is gone -- the reuse branch
+  never clears the atlas, by design. `false` with no `new renderer built`
+  line after it would mean the renderer failed to rebuild. Either answer
+  names the fix; guessing between them from here does not.
   The `GlyphAtlas::clear`/`Textures::reset` fix was verified on the
   emulator under `force-gles` only; the phone runs Vulkan. So either the
   reset is not reached on the phone's path (a different surface-