fix(mcp): report reconnect as pending while closing

[shenyankm]

Related Issue

Resolve #2956

Problem

During MCP reconnect, both connection managers awaited the previous client's asynchronous close() before publishing the pending state. Because closeClient() clears the active client synchronously, get() could still report connected with the previous tool count while resolved() already returned undefined.

What changed

• Start closing the previous client, immediately clear the resolved tool state, and emit pending before awaiting the close in both agent-core v1 and v2.
• Preserve the existing reconnect attempt guard before starting the replacement connection.
• Add mirrored regression tests that block the previous stdio client's close and verify the public state and status event.
• Add a patch changeset for @moonshot-ai/kimi-code.

Validation:

• Focused connection-manager tests: v1 44 passed; v2 42 passed.
• Full package tests: v1 4143 passed; v2 5067 passed.
• v1/v2 typecheck, v2 import-boundary lint, and type-aware oxlint on the four changed TypeScript files passed.

Checklist

• I have read the CONTRIBUTING document.
• I have linked a related issue, or explained the problem above.
• I have added tests that prove my feature works.
• Ran gen-changesets skill, or this PR needs no changeset.
• Ran gen-docs skill, or this PR needs no doc update.

[changeset-bot]

🦋 Changeset detected

Latest commit: 686ed94

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
@moonshot-ai/kimi-code	Patch

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[shenyankm]

@codex review

[chatgpt-codex-connector]

Codex Review: Didn't find any major issues. Nice work!

Reviewed commit: 686ed94d58

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