Generates the system message for the agent.
Default implementation returns empty string (for simple agents like JustAsk). Subclasses can override to generate system prompt with current context. For CodeAssistant, this should include open files, workspace, etc.
| handler |
Optional Base instance (can access session, client, etc.) |
|
System message content, or empty string if no system message needed |
| Error |
if system message generation fails |