feat: add interactive VT and workspace command plane

docs/UI_SPIKE_SCORECARD.md

@@ -21,9 +21,11 @@ from macOS and Linux and the hard gates pass.
 | Native menu/window/clipboard/drag-and-drop | review | pending | pending |
 | API clarity and maintenance burden | review | pending | pending |
 
-The current programs establish dependency, build, launch, and static layout
-baselines. The next iteration adds deterministic streaming, input timestamps,
-accessibility identifiers, a native Markdown editor, and one Wry browser child.
+The current programs establish dependency, build, launch, and interaction
+baselines. GPUI now routes a real PTY through a VT engine and keyboard encoder;
+its renderer still flattens the immutable screen snapshot to plain rows. The
+next iteration adds styled cells/cursor/selection, measured pane-driven resize,
+a native Markdown editor, and one isolated browser child.
 
 ## Ubuntu baseline — metal, 2026-08-31
 
@@ -85,7 +87,7 @@ fallback.
 
 Both renderers retain the same all-deterministic six-surface action stream for
 comparison. The GPUI integration mode replaces one terminal fixture with a real
-actor-owned PTY and leaves five deterministic surfaces running. Counters
+actor-owned VT session and leaves five deterministic surfaces running. Counters
 separate external PTY batches/lines from total model updates. The GPUI footer
 reports dispatch-to-element-build p50/p95 over a bounded 256-sample window. It
 is deliberately not called key-to-present or frame-present latency: neither