[FEATURE] Persist subagent outputs, optionally re-read after /compact

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

Complex subagent outputs are often lost after a /compact.

Proposed Solution

Persist in file storage the final outputs from subtask agents in retrievable format. Provide instructions in base prompt for recalling them if needed after /compact

Alternative Solutions

_No response_

Priority

Medium - Would be very helpful

Feature Category

CLI commands and flags

Use Case Example

_No response_

Additional Context

_No response_