Concepts/Definition

Application context: a complete chat history is still an incomplete hand-off

A requirements agent forwards tens of thousands of words to an implementation agent. The receiver can see what was discussed but cannot tell which decision is final, which paths were rejected, which resources it may change, or who will accept the result. Context volume increased; responsibility did not become clear.

Definition

A Handoff Contract is a typed boundary between collaboration stages. It carries the goal, existing artifacts, accepted decisions, open questions, authority scope, accountable owner, acceptance criteria, and the next required artifact. The receiver explicitly accepts or rejects it, and temporary authority from the previous leg is reclaimed by policy.

Engineering mechanism

goal: preserve public API compatibility
artifacts: [spec://417@sha256:...]
decisions:
  - do not change the public schema
authority:
  tools: [repo_read, patch_write]
  scope: repo://service-a
acceptance: [unit_tests, contract_tests]
next_required: reviewable patch and test evidence

The contract references large artifacts and history rather than copying them. A changed dependency, scope, or authority causes rejection or reissue instead of silent guessing.

Boundary

An ordinary function call needs only an argument contract. Explicit hand-off becomes important across roles, sessions, teams, or trust domains. Domain fields may vary, but goal, artifacts, decisions, authority, and acceptance should not exist only in conversation.