[FEATURE] Add "Restore conversation + summarize" option to rewind menu

Preflight Checklist

• [x] I have searched existing requests and this feature hasn't been requested yet
• [x] This is a single feature request (not multiple features)

Problem Statement

You start with a clean session, things go smoothly with low context noise for many messages, but then end up hitting a noisy back-and-forth that landed on correct implementation. I want to keep the changes but clean up the context segment by compacting away the noise.

Current rewind options:

| Option | Result |
|--------|--------|
| Restore code and conversation | Loses my code changes |
| Restore conversation | Loses all record of what I did |
| Restore code | Keeps the noise |

I want to rewind the conversation, keep my code, and preserve a summary of what was accomplished.

Proposed Solution

Add a 5th option to the rewind menu:

Confirm you want to restore to the point before you sent this message:

┃ "fix the auth bug"
┃ (2 hours ago)

The conversation will be forked.
The code will be restored: +0 -0 in session.ts

  1. Restore code and conversation
  2. Restore conversation
  3. Restore code
❯  4. Restore conversation + summarize   ← NEW
  5. Never mind

When selected:

1. Rewind conversation to the selected checkpoint
2. Keep all file changes made since that checkpoint
3. Auto-generate a summary of what was accomplished in the skipped messages (include files modified)
4. Insert that summary directly into the restored conversation

No preview/edit step—insert directly for fast flow. The summary should include which files were changed. Let the model decide appropriate length and whether to mention failed approaches (include if informative).

Even for short segments (2-3 messages), always generate a summary for consistent behavior.

Alternative Solutions

• Manual workflow: Ask Claude to summarize → copy → rewind conversation → paste. Works but clunky.

Priority

High - Significant impact on productivity

Feature Category

Interactive mode (TUI)

Use Case Example

Scenario: Debugging session cleanup

Messages 1-10:   Planning authentication feature, establishing approach
Messages 11-52:  Debugging session - stack traces, failed attempts, back-and-forth
Message 53:      Working implementation

After getting it working, I want to continue building on this feature with clean context.

Current workflow:

1. Ask Claude: "Summarize what we just accomplished"
2. Copy the summary
3. Esc+Esc → select checkpoint at message 10 → "Restore conversation"
4. Paste summary manually as my first message
5. Continue working

With this feature:

1. Esc+Esc → select checkpoint at message 10 → "Restore conversation + summarize"
2. Continue working

Result:

[Messages 1-10: Planning preserved]
[Auto-inserted summary: "Fixed authentication race condition by adding mutex lock to session handler. Modified: session.ts:47, auth.ts:122. Key decision: chose mutex over distributed lock due to single-instance deployment."]
[Fresh context, code changes preserved, ready to continue]

Additional Context

Future extension: The primary use case is "keep code" (preserve work, clean context). A future extension could support "restore code" variant for cases where you want to summarize exploratory work that didn't result in code changes, but that's a separate use case.

Implementation note: The infrastructure exists: checkpointing, conversation restore, and summarization are all already implemented. This combines them in a useful way.