subagent-env-handshake

To verify live repository state before dispatching a Claude subagent, prepend a v1 handshake block to the subagent prompt. This Markdown-HTML comment block passes six fields including parent_head, parent_branch, and parent_dirty_fingerprint to prevent environment drift.

Subagents act on stale parent environment data because they lack a verification mechanism for the live working tree. Without a handshake block checking parent_head and parent_cwd, subagents execute in shared working trees without confirming the current repository state before making tree-grounded claims.

To prevent environment drift when sharing a working tree with subagents, implement a handshake during Claude Code agent dispatch. Prepending the generated block to the Agent tool prompt ensures subagents verify HEAD, branch, CWD, and dirty state before proceeding with tree-sensitive tasks.

Yes, you can use a handshake to coordinate tree-sensitive tasks in Claude Code. The v1 handshake is designed for agent dispatch workflows where a parent session shares a live working tree, safely improving reliability when subagents execute tree-sensitive operations.

A Claude subagent environment handshake includes six fields: parent_head, parent_branch, parent_cwd, parent_dirty_fingerprint, workspace_mode, and handshake_issued_at. These fields capture the exact repository state to verify the live working tree before subagent execution.

Yes, the subagent handshake works without external dependencies. It relies solely on scripts to generate a Markdown-HTML comment block, ensuring the environment verification process integrates seamlessly into existing Claude Code subagent dispatch workflows without requiring additional packages.