Enriches timeline events with state structure information.

Tracks:

• Keys present in assigns
• Total key count
• Maximum nesting depth

Usage

Runs automatically during timeline building. Adds state metadata to each timeline event.

Example Output

%{
  sequence: 3,
  event: "handle_event:filter",
  state_keys: [:user_id, :products, :filters],
  state_key_count: 3,
  state_max_depth: 4
}