LiquidHandler events

The instrumented legacy.liquid_handling.LiquidHandler frontend emits these semantic operations. Each operation emits started, completed, or failed lifecycle records.

Operation	Primary fields
liquid_handler.resource_pickup	device, direct moved resources, source holder when assigned
liquid_handler.resource_move	device, direct moved resources
liquid_handler.resource_drop	device, direct moved resources, destination
liquid_handler.tip_pickup	device, direct resources, tip_operations
liquid_handler.tip_drop	device, direct resources, tip_operations
liquid_handler.tip_pickup_96	device, direct resources, tip_operations
liquid_handler.tip_drop_96	device, direct resources, tip_operations
liquid_handler.aspirate	device, direct resources, liquid_operations
liquid_handler.dispense	device, direct resources, liquid_operations

liquid_operations carries a record for each channel with channel, direct resource, optional owning plate, and volume. tip_operations similarly carries each channel and direct tip location. The direct tip or well is never substituted with a parent rack or plate; structural ancestors are available in the resource reference when needed.

For resource_pickup, source is the direct parent holder captured before PLR unassigns the resource after successful hardware pickup. It is omitted if the resource was already unassigned.