[FEATURE] Cross-context communication between Claude Code instances

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

When working on a codebase, it's common to have multiple Claude Code sessions running — for example, one exploring architecture while another implements a feature, or two sessions working on related parts of the system.

Currently each session is fully isolated with no ability to share context, findings, or coordinate work. This leads to duplicated exploration, conflicting changes, and lost context when switching between sessions.

Proposed Solution

Allow Claude Code instances to communicate or share context with each other. Possible approaches:

• Shared scratchpad/memory — A local file or store that instances can read/write to exchange findings, decisions, and progress
• Session handoff — Export a session summary that another instance can import as context
• Live messaging — Instances could send/receive short messages to coordinate (e.g., "I'm refactoring auth, don't touch src/auth/")
• Shared task board — Multiple instances contribute to and pull from a common task list

Use Cases

• Parallel work on related features without conflicts
• Handing off a research session's findings to an implementation session
• One instance reviews while another implements
• Splitting a large refactor across multiple sessions

Environment

CLI (Claude Code)