Build interactive native workspace vertical slice

docs/TESTING.md

@@ -101,6 +101,19 @@ cargo xtest
 2025. `scripts/watch.sh` uses Bacon and retains a cargo-watch fallback for people
 who already have the final cargo-watch release installed.
 
+## Implemented vertical-slice coverage
+
+- The framework-neutral six-surface model has deterministic tests for focus,
+  direct selection, needs-input transitions, command-palette lifecycle,
+  identical GPUI/Floem action replay, bounded output, and workload counters.
+- `lumbridge-pty` runs synthetic `/bin/sh` tests for raw output, non-zero exits,
+  input, resize, one-chunk backpressure, hung-process termination, invalid
+  dimensions, and exclusion of provider credentials from the child environment.
+- The current-GPUI probe compile-checks real AccessKit element wiring and real
+  platform input-handler installation. Unit tests cover its semantic tree and
+  UTF-16/UTF-8 composed-text mutations. OS screen readers, IME candidate windows,
+  and macOS behavior remain platform tests.
+
 ## CI matrix as the project grows
 
 Every change runs format, Clippy, unit, contract, integration, and doctests on