[FEATURE] Group sessions by sub-project within a single repository

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

Existing session organization is derived from the working directory or git repo root. That breaks for framework repos that host multiple onboarded apps in one repository. All sessions for every app collapse into one flat list under the same project, so there is no way to see only the sessions for the app I am currently working on. Renaming sessions with prefixes is manual and gives no real separation.

Proposed Solution

Allow sessions to be grouped below the repo level. Either derive the group from the subdirectory the session is working in (for example apps/<app-name>), or support user-assigned tags or groups on a session, with a filter in the /resume picker. New sessions started from within an existing group should inherit that group automatically.

Alternative Solutions

_No response_

Priority

High - Significant impact on productivity

Feature Category

File operations

Use Case Example

I work on a framework repo where multiple apps are onboarded. In a week I may have sessions for framework-level changes plus separate sessions for four different apps. Resuming the right one currently means scanning timestamps and first prompts, and it is easy to resume a session scoped to the wrong app.

Additional Context

_No response_