Build interactive native workspace vertical slice

docs/ARCHITECTURE.md

@@ -41,13 +41,17 @@ messages should be real from the beginning.
 - `lumbridge`: installable application entry point.
 
 The scaffold currently contains `lumbridge-core`, `lumbridge-storage`,
-`lumbridge-buzz`, and the entry point. Larger runtime crates are added after
-their architecture spikes pass.
+`lumbridge-buzz`, `lumbridge-pty`, and the entry point. Larger runtime crates are
+added after their architecture spikes pass.
 
 ## Terminal path
 
 The runtime owns PTYs, child process groups, resize signals, input ordering, and
-raw output. The terminal engine turns output into immutable render snapshots and
+raw output. The first `lumbridge-pty` boundary now uses `portable-pty` behind a
+single-owner session, a fixed credential-free child environment, validated
+sizes, an 8 KiB bounded output queue, resize/input/wait operations, and Unix
+process-group cleanup. It deliberately does not emulate a terminal or persist
+scrollback. The terminal engine turns output into immutable render snapshots and
 bounded deltas for the UI. Scrollback is chunked and persisted separately from
 the live screen to prevent large agent transcripts from blocking input.
 
@@ -59,15 +63,18 @@ and simultaneous automation plus human input.
 
 ## UI decision gate
 
-Do not lock the project to a webview or to Zed's private implementation details
-before a measured spike. Compare:
+Do not lock the project to a webview or to Zed's application implementation
+details. The measured spike compares:
 
 1. GPUI for a Zed-like native model and excellent text-heavy interaction.
 2. Floem for an independent native Rust model with existing editor primitives.
 
 The winner must render six busy panes smoothly, keep input latency low, support
 IME/accessibility, package on macOS and both Linux targets, and avoid a license
-or upstream-stability trap.
+or upstream-stability trap. Current Zed GPUI is the provisional winner because
+its AccessKit semantics compile while the pinned Floem revision has no semantic
+accessibility integration. This remains behind a narrow adapter until platform
+assistive-technology, IME, packaging, licensing, and release measurements pass.
 
 ## Local-first and remote session path