Fix: Handle first message in new chat sessions

[hadv]

Problem

When users sent their first message in a new chat session, they would receive a "No valid messages" error instead of an AI response. This occurred because:

• The context engine correctly returns empty arrays for recentMessages and relevantHistory on first messages
• The server was only using these arrays to build the message context for the LLM
• This resulted in an empty message array, which was correctly rejected by validation
• Users got error responses instead of AI replies when starting new conversations

Solution

Added logic to include the current user message when no context messages exist:

// If no context messages exist (first message), add the current user message
if (allContextMessages.length === 0) {
  allContextMessages.push({
    role: 'user',
    content: sanitizedMessage
  });
}

Changes

• Fixed both processing paths: Applied the fix to both MCP client and direct Anthropic API paths in server/src/index.ts
• Added comprehensive tests: Created server/src/tests/firstMessage.test.ts with tests for:
  • Empty context handling for first messages
  • MCP client context building
  • No interference with subsequent messages
• Minimal impact: The fix only triggers when context is empty, ensuring no impact on existing conversations

Testing

✅ All new tests pass
✅ Existing functionality unaffected
✅ First messages now generate proper AI responses
✅ Subsequent messages continue to work normally

Result

Users can now start new conversations and receive AI responses to their first messages instead of error messages.

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Pull Request opened by Augment Code with guidance from the PR author