Rewind to an earlier message from the chat view, for any agent, with the chat view following the rewound conversation #1189

Problem

Going back to an earlier message is how I keep a long chat focused on the current task, and agents have their own way to do it (Claude Code's /rewind, OpenCode's /undo, for example). The chat view has no way to reach it, for any agent:

• In Claude Code, sending /rewind from the chat composer opens its rewind menu only in the Terminal view, so I have to switch views and drive it with the arrow keys.
• After a rewind, the chat view still shows the turns that were rewound away, even though the session no longer has them. Tested on v0.4.8 (main a4b2295) with Claude Code 2.1.283: after rewinding past a "banana" exchange, Claude said it had only ever replied "apple", but the chat view still showed the "banana" turn.

Proposal

A Rewind to here action on each of my messages in the chat view, for every agent that has its own rewind or undo:

• Driven through that agent's own mechanism, with the per-agent key semantics on the server, the way prompt answers already are.
• Where the agent offers choices, show them as a card. Claude Code asks whether to restore the conversation, summarize from here, summarize up to here, or cancel.
• After a rewind, the chat view follows the session's active branch: rewound-away turns are hidden, or clearly marked as no longer in the conversation.
• Offered only while the agent is idle, never over a draft in the composer, and hidden for agents that have no rewind.

Where

Chat and prompt cards

Workarounds and alternatives

Today, for Claude Code: send /rewind, switch to the Terminal view, pick the point with the arrow keys and confirm; the chat view keeps showing the removed turns afterwards. Other agents: drive their own undo from the Terminal view.

Alternative: a per-message turn menu (rewind, copy) if that fits the design better than a button on each message.

Related: #1037 (tappable model and effort label), the other composer control I asked about.