MeanField/DEFERRED_REMOVAL_REGISTRY.md

Deferred Removal Registry

This registry records migration-era code that may become removable after the physics-facing StellarModel and StellarEquilibriumProblem APIs have replaced all legacy construction paths. Nothing listed here is currently approved for removal, and no listed code was removed during the migration.

mean_field::models::Model<...>

• Location: libmeanfield/interface/models/specifications.cppm
• Current status: required compatibility storage
• Current consumers: root-manifest tests and the implementation of mean_field::model::StellarModel
• Removal gate: migrate remaining direct consumers to the public mean_field::model::StellarModel type, then move the canonical storage into an implementation namespace
• Evidence required before removal: no direct consumers found by repository search and the complete specification/type-contract suite passes

Legacy structure-based mean_field::models::StellarModel

• Location: libmeanfield/interface/models/stellar_model.cppm
• Current status: retained legacy API, but no longer used by the authoritative StellarEquilibriumProblem construction path
• Current consumers: direct prepared-operator tests, experiments, and heterogeneous runtime-model views. Its polytropic initial-seed method now delegates to the physics-facing Lane-Emden seed generator.
• Removal gate: numerical operators consume compiled specification contributions directly, initial-seed generation has a physics-facing owner, and deformation policies have migrated into the typed model
• Evidence required before removal: legacy-adapter equivalence tests pass for all supported formulations and repository search finds no direct consumers

PolytropicStructure as a mass-owning adapter

• Location: libmeanfield/interface/models/structure/polytropic.cppm
• Current status: compatibility adapter for remaining legacy API consumers; it no longer owns Lane-Emden integration and is not constructed by StellarEquilibriumProblem
• Potentially obsolete responsibility: ownership of the fixed-total-mass target, which now belongs to FixedTotalMass
• Removal gate: migrate remaining callers to seed::LaneEmden and the typed model. Lane-Emden generation is now separate from invariant ownership.
• Evidence required before removal: initial-seed regression tests and model-driven equilibrium equivalence tests pass

Legacy combined prepared operators

• Locations: libmeanfield/interface/operators/prepared_fixed_angular_momentum_stellar_equilibrium.cppm and libmeanfield/interface/operators/prepared_central_density_stellar_equilibrium.cppm
• Current status: retained as migration-era source references, but removed from the build graph and no longer re-exported by the public mean_field module
• Physics-facing replacement: PreparedVariadicStellarEquilibriumOperator<Model>, selected solely by StellarEquilibriumProblem<Model, Discretization>
• Reactivation gate: migrate the source snapshots to the model-driven manifest constructor; they intentionally do not compile against the authoritative API
• Removal gate: delete the source snapshots after the historical comparison window closes
• Evidence required before removal: the full variadic residual/Jacobian equivalence suite and distributed tests pass without either partition being imported by a user translation unit

Completed: typed equilibrium-problem adapter removal

• Removed the former typed system's NumericalModelAdapter, its PolytropicStructure, and the corresponding legacy model storage.
• The typed problem now owns its compiled surface constraint and constructs the prepared operator directly from specification-generated contributions.
• Default radial deformation is compiled at the numerical equilibrium-problem boundary rather than being smuggled through a legacy stellar model.

StellarEquilibriumSystem compatibility vocabulary

• Location: libmeanfield/interface/operators/stellar_equilibrium_system.cppm
• Current status: source-compatible aliases and factory forwarding to StellarEquilibriumProblem and equilibrium::discretize
• Removal gate: migrate remaining external consumers and provide a documented deprecation interval
• Evidence required before removal: repository search finds only the explicit compatibility type-contract test

Root-oriented public aliases and accessors

• Locations: libmeanfield/interface/operators/root_manifest.cppm, libmeanfield/interface/operators/prepared_stellar_equilibrium.cppm, and libmeanfield/interface/operators/prepared_central_density_stellar_equilibrium.cppm
• Current status: retained for source compatibility
• Physics-facing replacements: EquilibriumSystemManifest, EquilibriumStateView, EquilibriumResidualView, and StellarEquilibriumProblem::GetManifest()
• Removal gate: all solver and test consumers use equilibrium-system terminology
• Evidence required before removal: repository search finds no uses of the old aliases/accessors and all manifest/type-contract tests pass

Conclusion for this phase

No code examined during this migration is presently truly dead. Each candidate still has active consumers or carries a compatibility/lifetime responsibility. The entries above are therefore deferred migration candidates, not deletion recommendations.