fix: convert dict to KernelSnapshot in kernel state endpoint

[nmlemus]

Problem

The GET /api/sessions/{session_id}/kernel endpoint was returning a 500 Internal Server Error:

{"detail": "Error getting kernel state: 'dict' object has no attribute 'variables'"}

Root Cause

The get_kernel_state() method in ConversationalAgent returns a Dict[str, Any], but the _snapshot_to_response() function expected a KernelSnapshot object and tried to access .variables as an attribute.

Solution

Added type checking and conversion logic to handle both cases:

• If a dict is returned, convert it to a KernelSnapshot object
• If a KernelSnapshot is already returned, use it directly

Testing

• Tested the endpoint manually and confirmed it now returns the kernel state correctly

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