feat: Design <scope> tag for shared data across agents

[sergio-sisternes-epam]

Summary

Design a new <scope> top-level tag that provides shared data accessible to all child agents within a session.

Motivation

During smoke testing, an agent identified that sibling agents within a session cannot share data. For example, a test-engineer agent cannot access a login() function defined in a reviewer agent's scope. Each agent receives only its own <skill> content.

Proposed Design

<session name="review-pipeline">
  <scope name="code-under-review">
    def login(username, password):
        return db.execute(query)
  </scope>

  <agent name="reviewer">
    <skill interface="code-review">
      Review all code in scope "code-under-review".
    </skill>
  </agent>

  <agent name="tester">
    <skill interface="testing">
      Test the login() function from scope "code-under-review".
    </skill>
  </agent>
</session>

Design Questions

• Is <scope> a new top-level tag or an attribute on <session>?
• Should scopes be mutable (agents can modify shared state)?
• How do scopes interact with session isolation (isolated="true")?
• Should scopes support inheritance (nested sessions inherit parent scopes)?

Related

• Discovered during directive smoke testing (ADR-010)
• Related to consumes attribute for explicit data flow