A system is being replaced, retired or moved.
Migration
We switch this platform off in the new year. Half its jobs were written by people who have left, and I have to say what must survive the move.
The migration lead
What must be preserved before this system is replaced?
The product at work
The old platform's logic, read as it is: one plain statement per step.
The new platform's logic beside it, read the same way.
The differences marked: kept, changed, and left behind.
The Lineage record for the plan, and the CGS Docs: Cosmogenesis Systems' documentation of the reading.
What usually happens
The team lists the jobs it knows about, and a whiteboard fills with boxes and arrows drawn from memory. Something is missed, turns up in the first month on the new platform, and the old one runs another year just in case.
With a reading
With a reading, the old system's code is read as it is, and what depends on what comes out as a map, which shows the logic worth keeping and the dependencies that reach other systems. The question of what must survive is answered from the code.
A source-linked inventory of the logic, dependencies and unresolved areas that must be considered before replacement or retirement.
The inventory says what the old platform's code does. What must survive the move is a decision for its owners, made with the inventory in hand.
Who it is for
For the migration lead, platform owner or programme sponsor replacing a system nobody understands in full.
What to bring
The code, configuration and job schedules of the system being replaced, and of the systems it talks to where available.