refactor(tidy3d): FXC-5286-pydantic-v-2-refactor-validator-sprawl

[marcorudolphflex]

Refactors validator hotspots by consolidating multiple @model_validator(mode="after") hooks into a single orchestrator validator that invokes ordered helper methods. This preserves existing warning/error ordering and messages while improving readability and maintainability. Tests are added/updated to lock in validation order where needed.

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Note

Medium Risk
Touches core model validation paths for mediums and simulations, so regressions could change warning/error timing or behavior even though the checks themselves are largely unchanged.

Overview
Refactors Pydantic v2 post-init validation for the Medium and Simulation class families by replacing many scattered @model_validator(mode="after") methods with a single _run_after_validators() orchestrator per class that calls helper checks in an explicit order.

Adds call_wrapped_validator(...) to invoke existing validator factories deterministically, updates several simulation variants (Simulation, ModeSimulation, EMESimulation, TCAD heat/charge) and multiple medium subclasses to follow the new pattern, and renames/privatizes various validator helpers for consistency.

Tests and policy enforcement: adds new tests to lock in validator warning/error ordering (e.g., CustomMedium, Simulation) and introduces test_validator_policy.py to prevent new mode="after" validators from being added outside _run_after_validators() in the medium/simulation hierarchies.

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[github-actions]

Diff Coverage

Diff: origin/develop...HEAD, staged and unstaged changes

• tidy3d/components/eme/simulation.py (100%)
• tidy3d/components/medium.py (100%)
• tidy3d/components/mode/simulation.py (100%)
• tidy3d/components/simulation.py (100%)
• tidy3d/components/tcad/simulation/heat_charge.py (100%)
• tidy3d/components/validators.py (100%)

Summary

• Total: 181 lines
• Missing: 0 lines
• Coverage: 100%

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Cursor Bugbot has reviewed your changes and found 2 potential issues.

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[yaugenst-flex]

@marcorudolphflex thanks, this looks good directionally. But as evidenced by this thread i think we need to improve the process design here too. At the very least there should be some docstrings, and also a contributor doc (could add this to AGENTS.md too) that documents the correct way to add validators in this style.

[marcorudolphflex]

@marcorudolphflex thanks, this looks good directionally. But as evidenced by this thread i think we need to improve the process design here too. At the very least there should be some docstrings, and also a contributor doc (could add this to AGENTS.md too) that documents the correct way to add validators in this style.

That makes definitely sense! Added some notes to Agents.md and docs/development/introduction/code_quality_principles.rst