[FEATURE] cleanupPeriodDays should default to unlimited retention. Archive instead.

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

It is very wrong that cleanupPeriodDays has a low default retention of 30 days. These session rollup jsonl's have cost BILLIONS USD to produce; Paid with user money either via subsidized subscriptions or at actual API pricing. They potentially contain a treasure trove of mineable knowledge and insights, or a proof of work justifying the spend.

Plus this: https://github.com/anthropics/claude-code/issues/62272

Proposed Solution

The suggested default shape is to archive (move and zip by month) not discard old JSONLs, unless configured otherwise.

Alternative Solutions

_No response_

Priority

Medium - Would be very helpful

Feature Category

Configuration and settings

Use Case Example

_No response_

Additional Context

_No response_