fix(cli): prevent swarm agents from messaging themselves

[marius-kilocode]

What Problem This Solves

Shared board agents could post a message to their own session, despite the board guidance telling them to notify other participants.

Why This Change Was Made

The board store resolved recipient aliases but did not compare the resolved recipient with the sending session. The store now rejects direct self-targeted messages after alias resolution.

User Impact

Parent and child sessions cannot send direct messages to themselves. Parent-to-child, child-to-parent, sibling, and ALL broadcasts remain supported.

Evidence

• Focused board tests pass: 27 tests.
• Live board integration tests pass: 6 tests.
• CLI typecheck passes.
• VS Code Agent Manager self-test displayed Board messages cannot be sent to yourself and completed the flow.

[kilo-code-bot]

Code Review Summary

Status: No Issues Found | Recommendation: Merge

Files Reviewed (4 files)

• .changeset/prevent-self-board-messages.md
• packages/opencode/src/kilocode/board/store.ts
• packages/opencode/test/kilocode/board-tools.test.ts
• packages/opencode/test/kilocode/board/store.test.ts

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_{Reviewed by grok-4.6 · Input: 111.4K · Output: 5.6K · Cached: 264.2K}

_{Review guidance: REVIEW.md from base branch main}