fix: make workspace panels self contained

docs/UX_VERTICAL_SLICE.md

@@ -10,14 +10,14 @@ framework decision gate, not a decorative dashboard.
 ## Current-run audit
 
 The first 2026-08-31 GPUI baseline proved six-surface density but gave every
-pane equal visual priority. The current slice replaces that dashboard with three
-horizontal bands: 20% context and pane selection, a 60% responsive work region,
-and a 20% decision shelf. The work region shows one, three, or five vertical
-lanes according to available width. Keyboard focus, command-palette input, live
-PTY input, styled VT cells, cursor shapes, geometry-driven resize, and retained-
-history navigation are wired. Remaining visible gaps are terminal text selection
-and mouse modes, real decision-shelf actions, usage-detail provenance, and end-to-
-end platform accessibility/IME.
+pane equal visual priority. The current slice replaces that dashboard with one,
+three, or five cmux-style vertical panels according to available width. Every
+panel owns its own 20% context region, 60% work surface, and 20% decision shelf.
+Keyboard focus, command-palette input, live PTY input, styled VT cells, cursor
+shapes, geometry-driven resize, and retained-history navigation are wired.
+Remaining visible gaps are terminal text selection and mouse modes, real
+decision-shelf actions, usage-detail provenance, and end-to-end platform
+accessibility/IME.
 
 Screenshots for the audit are stored outside Git under
 `~/shots/2026-08/lumbridge-ui-audit/`. Accessibility and IME correctness cannot
@@ -42,8 +42,8 @@ research, not source assets for Lumbridge. We adapt these interaction patterns:
   cards;
 - a quiet top tab strip for mixed terminal, Markdown, browser, and review
   surfaces;
-- a primary work region with a small responsive number of equal vertical lanes,
-  instead of either one ultrawide terminal or a dense equal-card dashboard;
+- a small responsive number of self-contained vertical panels, instead of
+  either one ultrawide terminal or a dense equal-card dashboard;
 - narrow contextual tools, such as files, review, or Buzz, that can collapse
   when the terminal needs the space;
 - usage and agent state at the edge of the workspace rather than in modal
@@ -60,20 +60,21 @@ surface rather than a hosted Lumbridge control plane.
    palette shortcut.
 2. The sidebar starts with a compact `ATTENTION` group, followed by workspaces
    and remote hosts. It does not become a notification feed.
-3. A compact top 20% context band keeps all pane identities and states visible;
-   the selected pane receives the accent treatment.
-4. A waiting pane uses an amber semantic label in both the context band and
-   attention sidebar. The label always includes words such as `NEEDS INPUT`.
-5. The middle 60% gives one, three, or five terminal/work lanes uninterrupted
-   height and retains target, harness state, dimensions, and surface tabs. The
-   selected lane alone owns keyboard input.
+3. The top 20% of every visible panel keeps that pane's identity, surfaces,
+   execution target, context, goal, and state visible; the selected panel
+   receives the accent treatment.
+4. A waiting pane uses an amber semantic label in both its panel context region
+   and the attention sidebar. The label always includes words such as
+   `NEEDS INPUT`.
+5. The middle 60% of every panel gives its terminal or work surface uninterrupted
+   height. The selected panel alone owns keyboard input.
 6. The footer groups connection state, selected-harness identity, usage-window
    provenance, and burn forecast into readable regions.
 7. The selected pane has a quiet surface strip for Terminal, Browser, Tools,
    Context, Goal, and Review. Switching surfaces keeps one pane identity.
-8. A compact decision shelf may show local-analyst choices below the work
-   surface. It labels its model/provider, trace scope, and whether suggestions
-   are inert; no choice is visually conflated with an approved action.
+8. Every panel has a compact decision shelf below its work surface. It labels
+   whether suggestions are inert or review is required; no choice is visually
+   conflated with an approved action.
 
 ## Keyboard task flow