Implement message dispatching and handling for Claude agent interactions

[TylerLeonhardt]

This should make messaging handling in Claude a little easier to manage and test.

[Copilot]

Pull request overview

This PR refactors Claude session message handling by introducing a centralized dispatcher for Claude Agent SDK message types, making the message-processing logic easier to reason about and unit test.

Changes:

• Added claudeMessageDispatch.ts to route SDK messages to focused handlers (assistant/user/result/compact boundary) and share per-loop state.
• Updated claudeCodeAgent.ts to use the dispatcher instead of inlining message handling logic.
• Added comprehensive unit tests for dispatching and individual handlers in claudeMessageDispatch.spec.ts.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

File	Description
src/extension/chatSessions/claude/node/claudeCodeAgent.ts	Replaces inline message-type branching with dispatchMessage(...) invocation to centralize handling.
src/extension/chatSessions/claude/common/claudeMessageDispatch.ts	Introduces dispatch + handler functions for SDK message types, including tool span tracking and TodoWrite forwarding.
src/extension/chatSessions/claude/common/test/claudeMessageDispatch.spec.ts	Adds unit coverage for dispatch routing, handler behavior, and known/unknown message key logging.