tlaplus-add-variable

To add a variable to a TLA+ specification without changing semantics, declare the new variable, initialize it in Init, and add it to all UNCHANGED statements and the vars tuple. This ensures the model preserves its existing behavior.

When introducing a new variable in TLA+, all UNCHANGED statements must be updated to include it. If a statement currently references a single variable, it must be converted into a tuple format to correctly preserve the specification's semantics.

You need to update TypeOk invariants when adding a variable to a TLA+ model if the specification uses them. The new variable should be constrained by the TypeOk invariant to maintain type correctness within the extended specification.

You can safely add per-thread variables to a TLA+ specification by ensuring each variable is declared, initialized in Init, and integrated into all relevant UNCHANGED tuples and vars definitions, preventing unintended semantic shifts during model checking.

Adding a variable to a TLA+ spec breaks the model checker if the variable is missing from Init or UNCHANGED statements. Proper integration into the vars tuple and TypeOk invariants is required to prevent state constraint violations.