fix(rectification): open history cases with their bound skill identity (BUG-621)

Session open was sending the live registry version into v2, so every Skill
bump rejected older cases with an unmapped 500 and no error on the clicked row.

Co-authored-by: Cursor <cursoragent@cursor.com>

frontend/src/components/app-sidebar.tsx

@@ -62,6 +62,9 @@ export type AppSidebarProps = {
   activeSessionId: string | null;
   /** A rectification session whose Case is being opened and hydrated; its row says so, statically. */
   openingSessionId?: string | null;
+  /** Open failed for this history session; shown under that row only. */
+  openErrorSessionId?: string | null;
+  openErrorMessage?: string;
   account: SidebarAccount;
   accountMenuOpen: boolean;
   accountTriggerRef: Ref<HTMLButtonElement>;
@@ -86,6 +89,8 @@ export function AppSidebar({
   charts,
   activeSessionId,
   openingSessionId = null,
+  openErrorSessionId = null,
+  openErrorMessage = "",
   account,
   accountMenuOpen,
   accountTriggerRef,
@@ -159,6 +164,7 @@ export function AppSidebar({
           session={session}
           active={session.id === activeSessionId}
           opening={session.id === openingSessionId}
+          error={session.id === openErrorSessionId && openErrorMessage ? openErrorMessage : undefined}
           disabled={sessionControls.disabled}
           menuOpen={sessionControls.menuSessionId === session.id}
           onMenuOpenChange={(open) => sessionControls.onMenuSessionChange(open ? session.id : null)}

frontend/src/components/sidebar-session-row.tsx

@@ -46,6 +46,8 @@ type SidebarSessionRowProps = {
   readonly active: boolean;
   /** Its Case is being opened: a static note, no spinner. */
   readonly opening?: boolean;
+  /** Open failed for this row: one line under the title, same notice scale as composer. */
+  readonly error?: string;
   readonly disabled: boolean;
   readonly menuOpen: boolean;
   readonly onMenuOpenChange: (open: boolean) => void;
@@ -61,6 +63,7 @@ export const SidebarSessionRow = forwardRef<HTMLButtonElement, SidebarSessionRow
   session,
   active,
   opening = false,
+  error,
   disabled,
   menuOpen,
   onMenuOpenChange,
@@ -110,6 +113,9 @@ export const SidebarSessionRow = forwardRef<HTMLButtonElement, SidebarSessionRow
         >
           <MoreHorizontal aria-hidden="true" />
         </Menu.Trigger>
+        {error ? (
+          <p className="session-open-error" role="alert">{error}</p>
+        ) : null}
       </div>
       <Menu.Portal>
         <Menu.Positioner className="session-actions-positioner" side="bottom" align="end" sideOffset={4} collisionPadding={12}>