Public API and schema lifecycle

NeqSim public contracts include Java and Python APIs, JSON schemas, DEXPI representations, MCP tools, command-line interfaces, and persisted model or engineering packages.

Compatibility rules

• Additive optional fields and methods are permitted within a major contract version.
• Required fields, identifiers, enum meanings, and existing method behavior are not removed or redefined within a major version.
• Readers reject unknown major schema versions instead of interpreting them as the current contract.
• Writers emit one declared schema version and include an explicit schema URI.
• Deterministic artifacts retain stable ordering and content fingerprints.

Deprecation

Deprecation requires documentation of the replacement and migration path. A deprecated public contract remains supported for at least one normal release cycle and, when included in an LTS release, until the next LTS line unless a security or correctness issue makes that unsafe.

Breaking changes

A breaking change requires an accepted NRC, a new major contract version, migration documentation, compatibility tests, and release notes. Where practical, NeqSim should provide a reader or converter for the immediately preceding major version.

Qualification boundary

API stability says that integrations can rely on a contract. It does not say that the underlying calculation is qualified for a particular project, standard, operating range, or engineering decision.

Legacy TP-flash solver migration

SysNewtonRhapsonTPflashNew is deprecated following issue #4212. It is the legacy JAMA-based solver; the production TPflash implementation uses SysNewtonRhapsonTPflash. Application callers should migrate to ThermodynamicOperations.TPflash() so that the normal stability and equilibrium orchestration remains in control.

This deprecation preserves the class, constructor, methods, serialized version identifier and numerical implementation. It does not redirect existing calls or claim equivalent intermediate states: the legacy solver uses logarithmic K-value variables, whereas the current Newton solver uses Michelsen’s u variables. Direct users must compare their fluid cases and convergence behavior when migrating.

Removal remains a separate change after the required release-cycle/LTS deprecation period and the breaking-change process above. Absence of in-repository callers alone does not establish absence of external users. No removal date is promised.