wip: pane/session + tab-bar checkpoint

Second checkpoint of in-flight work (sessions route, api types, ChatTabBar,
PaneHeaderActions, Workspace, useWorkspacePanes) so the Orchestrator branch
can rebase onto current main before merge.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

apps/web/src/components/PaneHeaderActions.tsx

@@ -12,14 +12,9 @@ import { cn } from '@/lib/utils';
 // desktop coder + terminal pane headers (Workspace) so all pane kinds share one
 // control set. Extracted to avoid a divergent copy per header.
 interface Props {
-  // When provided, the "+" menu item matching `tabKind` opens an in-pane tab
-  // (e.g. chat panes: New BooChat → tab; coder panes: New BooCode → tab). Every
-  // OTHER kind splits into a new pane. When onNewTab is omitted (terminal
-  // panes, which can't host tabs) all three items split.
-  onNewTab?: () => void;
-  // The host pane's own kind — the "+" item of this kind becomes "new tab".
-  // Defaults to 'chat' for back-compat with the chat tab bar.
-  tabKind?: 'chat' | 'terminal' | 'coder';
+  // Mixed tabs: the "+" menu adds a tab of the chosen kind to THIS pane. Split
+  // (the second control) adds a new pane.
+  onNewTab: (kind: 'chat' | 'terminal' | 'coder') => void;
   onSplitPane: (kind: 'chat' | 'terminal' | 'coder') => void;
   onReopenPane?: () => void;
   onShowHistory: () => void;
@@ -35,7 +30,6 @@ const BTN =
 
 export function PaneHeaderActions({
   onNewTab,
-  tabKind = 'chat',
   onSplitPane,
   onReopenPane,
   onShowHistory,
@@ -43,10 +37,6 @@ export function PaneHeaderActions({
   historyActive,
   className,
 }: Props) {
-  // The "+" item of the host pane's own kind adds a tab; every other kind
-  // splits into a new pane. Falls back to split when onNewTab is absent.
-  const newOrSplit = (kind: 'chat' | 'terminal' | 'coder') =>
-    onNewTab && tabKind === kind ? onNewTab : () => onSplitPane(kind);
   return (
     <div className={cn('flex items-center gap-0.5 shrink-0', className)}>
       <DropdownMenu>
@@ -55,22 +45,21 @@ export function PaneHeaderActions({
             type="button"
             onClick={(e) => e.stopPropagation()}
             className={BTN}
-            aria-label="New chat, terminal, or coder"
-            title="New chat / terminal / coder"
+            aria-label="New tab"
+            title="New tab (chat / terminal / coder)"
           >
             <Plus size={12} />
           </button>
         </DropdownMenuTrigger>
         <DropdownMenuContent align="end" className="w-fit">
-          {/* The item matching the host pane's kind opens an in-pane tab; the
-              others split into a new pane. (tabKind defaults to 'chat'.) */}
-          <DropdownMenuItem onSelect={newOrSplit('chat')}>
+          {/* Mixed tabs: every item adds a tab of that kind to THIS pane. */}
+          <DropdownMenuItem onSelect={() => onNewTab('chat')}>
             <MessageSquare size={14} /> New BooChat
           </DropdownMenuItem>
-          <DropdownMenuItem onSelect={newOrSplit('terminal')}>
+          <DropdownMenuItem onSelect={() => onNewTab('terminal')}>
             <Terminal size={14} /> New BooTerm
           </DropdownMenuItem>
-          <DropdownMenuItem onSelect={newOrSplit('coder')}>
+          <DropdownMenuItem onSelect={() => onNewTab('coder')}>
             <Code size={14} /> New BooCode
           </DropdownMenuItem>
         </DropdownMenuContent>