[BUG] Branched session re-renders prior slash command invocations as raw <command-message>/<command-name> XML tags

Summary

After running /branch, slash commands from the pre-branch portion of the conversation re-render as raw XML tags (<command-message>...</command-message> <command-name>/...</command-name>) instead of as a styled command chip. The (Branch) label next to the command renders correctly.

Environment

• Claude Code: 2.1.139
• OS: CachyOS Linux (Arch-based), kernel 7.0.5-2-cachyos
• WM: Hyprland (Wayland)
• Terminal: Ghostty 1.3.1-arch2.2 (TERM=xterm-ghostty, COLORTERM=truecolor)
• Shell: fish

Repro

1. In a session, invoke any slash command (e.g. /statusline). It renders as a chip.
2. Run /branch to fork the conversation.
3. In the new branched session, scroll up to the earlier /statusline turn.

Expected: command still rendered as a styled chip with (Branch) indicator.
Actual: command shows as literal <command-message>statusline</command-message> <command-name>/statusline</command-name> (Branch).

Screenshot

_To be attached after issue creation._

Notes

• New slash commands invoked after the branch still render correctly.
• Only the replayed pre-branch turns are affected.