revert the chat tabs and panes work, back to one conversation

Andre asked for zero, not another fix on top. Reverts ec4f06a..7726c9f — the ten commits from
"tabs and panes" onward: the tab bar and pane splitting, tab renaming and its page title, the
per-server directory picker, the render-loop fix, pane transcript resolution, the send queue,
the two socket fixes from the other session, the pane-socket notes, and my own socket-set change
from tonight. He is rebuilding from here.

Deliberately KEPT: dc6b623, "talk to two officers at once from one browser". That was a separate
ask that predates the tabs one, and the multi-server client, the server chips and the connections
store stand on their own without panes. Reverting it too is one more command if that was the
intent.

Collateral, worth naming: cb7ab55 carried an unrelated MusicPlayerHost change alongside its
socket instrumentation, so that came out with it.

Reverts, not a reset — every one of these is pushed and a second session is live in this repo.

Typecheck clean. 600 pass, 2 fail — cliamp path-escape and the pty transport test, both failing
identically before this and unrelated to chat.

What is NOT explained by this revert: the browser symptoms tonight. The server was verified good
throughout — two real turns streamed back through the public URL on both models, and the full
2,281-message history came through nginx intact. Whatever the client fault is, it is still
unfound, and the pre-tabs code is where it now has to be looked for.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

src/apps/officer-web/Screens/Dashboard/ChatHistory/index.tsx

@@ -1,12 +1,15 @@
 import { useEffect, useRef } from 'react';
 import { useParams, useNavigate } from 'react-router';
-import type { SelectedSession } from 'officerdev';
-import { ChatTabs, chatListPath, cwdFromSplat, useSelectedChatSession } from 'officerdev';
+import type { LayoutNode, SelectedSession } from 'officerdev';
+import { WorkspaceView, chatListPath, cwdFromSplat, useSelectedChatSession } from 'officerdev';
 import { toast } from '@/components/ui/sonner';
+import { useIsMobile } from 'hooks/useIsMobile';
 import { useClient } from 'hooks/useClient';
 import { serverClient } from 'hooks/useServerClient';
 import { errorText } from 'helpers/error-text';
+import { useDashboardState } from 'state/useDashboardState';
 import type { ClaudeSessionDetail } from 'state/useClaudeSessions';
+import { defaultLayout, hasAppType } from './defaultLayout';
 
 // How many messages to render on first open (anchored to the bottom); scroll-up pages older ones in.
 const CHAT_TAIL = 20;
@@ -25,7 +28,26 @@ export const SessionListPage = ({ isNew }: SessionListPageProps) => {
   selectedRef.current = selected;
   // A layout persisted before the chat panels were renamed still names `officerdev/chat`, which no
   // longer resolves; `appTypes` lands anything unknown on the detail panel.
+  const workspace = useDashboardState<LayoutNode>('screens/chat', defaultLayout);
+  const isMobile = useIsMobile();
   const navigate = useNavigate();
+  const mobilePanelId = isMobile && (sessionId || isNew) ? 'chat-detail' : undefined;
+
+  // Adopt a structural change to this screen's layout.
+  //
+  // `useDashboardState` seeds its default ONLY when the key is absent, so anyone who has ever opened
+  // /chat keeps the shape it had then — for good. `appTypes`/`normalizeLayout` does not help: it repairs
+  // which app a panel runs, never the tree, so adding the Live panel above the list would have been
+  // invisible to every existing user and visible only on a fresh account.
+  //
+  // Replacing outright is safe *here* specifically because the screen is `locked`: its structure is
+  // dictated by code and the only thing a user can have contributed is the column sizes, which is a
+  // cheap thing to lose once. Terminates because the replacement contains the panel it tests for.
+  useEffect(() => {
+    if (!workspace.isLoaded) return;
+    if (hasAppType(workspace.value, 'chat-live')) return;
+    workspace.setValue(defaultLayout);
+  }, [workspace.isLoaded, workspace.value, workspace.setValue]);
 
   // Retire a legacy `?cwd=`. Nothing reads it any more and nothing writes it, but a refresh re-requests
   // the address bar verbatim — so one left over from before the path-based groups sits there forever,
@@ -98,15 +120,20 @@ export const SessionListPage = ({ isNew }: SessionListPageProps) => {
     // eslint-disable-next-line react-hooks/exhaustive-deps
   }, [sessionId, isNew, groupCwd]);
 
-  // The tabbed, multi-pane chat replaces the fixed three-panel workspace. The panels themselves are
-  // unchanged and still registered for the dashboard; what changes is that a PANE owns its conversation
-  // rather than the whole screen sharing one, which is what lets two machines be live side by side.
-  //
-  // `useDashboardState`/`WorkspaceView` are no longer used here. The layout that matters now is the tab
-  // blob in localStorage, because a tab spanning two servers cannot be stored per server.
   return (
     <div className="h-full w-full pt-2">
-      <ChatTabs />
+      <WorkspaceView
+        workspace={workspace}
+        locked
+        appTypes={{ allowed: ['chat-session-list', 'chat-live', 'chat-detail'], fallback: 'chat-detail' }}
+        mobilePanelId={mobilePanelId}
+        onMobilePanelChange={(id) => {
+          // Back goes to the group's list, not the default one. On /chat/g/* that group is in the URL;
+          // on /chat/<id> it isn't (deliberately — see chat-routes.ts), so fall back to the open
+          // session's own directory, which the resolve above put on the selection.
+          if (!id) navigate(chatListPath(groupCwd ?? selectedRef.current?.cwd ?? null), { replace: true });
+        }}
+      />
     </div>
   );
 };