v2.12.0.dev3

What's Changed

Added

• Added tidy3d.RadiationBC gray-body surface radiation boundary condition and an optional emissivity field on tidy3d.ConvectionBC for combined convective-radiative heat exchange, supported in heat and conduction+heat simulations.
• Added SurfaceRecombinationBC for modeling Shockley-Read-Hall surface recombination and fixed interface sheet charge on semiconductor boundaries and zone interfaces, supported by the accelerated charge solver.
• Added ThinLensProfile, ThinLensBeam, and ThinLensOverlapMonitor for constructing,
  injecting, and decomposing vectorial focused beams from a thin-lens angular spectrum.
• Added tidy3d.web.diagnose_connection() and the tidy3d diagnose-connection CLI for measuring Tidy3D API reachability, DNS/TCP/TLS connectivity, client SSL/proxy/CA configuration, and storage download throughput.
• LumpedResistor, LinearLumpedElement, and LumpedPort now accept one-dimensional (line) geometries with two zero-size dimensions, in addition to planar geometries; a line element/port is realized as a single-grid-cell-wide Medium2D sheet whose normal axis is chosen at meshing time to straddle any adjacent material interface.
• AnisotropicConductivity for SolidMedium.conductivity, specifying an anisotropic (tensor) thermal conductivity via principal values xx, yy, zz plus an optional rotation. A scalar conductivity remains fully supported for isotropic materials. SolidMedium.from_si_units also accepts an AnisotropicConductivity (its principals are converted from SI units).
• Added ElectromagneticFieldData.field_intensity() for computing intensity from selected electric field components using the existing colocated intensity semantics.
• VarshniEnergyBandGap and ConstantEnergyBandGap now expose a band_gap_energy(temperature) method returning the energy band gap (in eV) at the requested temperature(s).
• Added geometry_tolerance to unstructured grid specs, raising the distance below which coincident geometric entities are fused during heat/charge meshing (refinement lines remain subject to a built-in 1e-6 um minimum length).

Changed

• Gaussian-like overlap monitors now require their monitor plane to lie in a homogeneous, isotropic background medium.
• The relax_courant option is now orientation independent and benefits a wider range of simulations.
• Consolidated the TCAD band-gap classes into a single module: ConstantEnergyBandGap and VarshniEnergyBandGap now live in tidy3d.components.tcad.bandgap (previously tidy3d.components.tcad.bandgap_energy, which has been removed) alongside SlotboomBandGapNarrowing. The public import path (import tidy3d as td; td.ConstantEnergyBandGap) is unchanged; only code importing directly from the internal bandgap_energy module path needs to update its import.
• Finest grid region visualization in Simulation.plot_grid() is now off by default; opt in by passing a nonzero finest_grid_region_alpha.

Fixed

• Fixed autograd runs so unsupported traced source, medium, and geometry parameters are rejected during setup, before simulation submission.
• Fixed doping behavior at box boundaries in charge simulations, for all doping box types (ConstantDoping, GaussianDoping, CustomDoping): doping near a box edge is no longer dropped, two boxes that abut along a plane no longer double the doping on that shared plane (the later box in the list takes the shared plane), and overlapping boxes (such as a background plus an implant) now add together correctly. Doping plots reflect the same combined doping the simulation uses.
• Simulations now validate that the grid resolves each lumped element and port before upload: at least two cells are required along every axis transverse to the voltage_axis. A too-coarse grid (for example a single cell across a transverse axis) previously failed during meshing with a cryptic "zero volume", IndexError, or divide-by-zero; it now raises a clear error pointing at the offending axis. This applies to both planar and one-dimensional (line) elements.
• Fixed loading of solver-generated heat, charge, and mesh results so Tidy3D no longer emits misleading unused-point or missing-value warnings.
• Union fields on Tidy3D models are now validated against their type discriminator, so passing an object of the wrong type to a model field raises a clear error at construction instead of being silently accepted and failing later during serialization or a remote run.
• Fixed local EME staged propagation rejecting EMEModeSpec.interp_spec mode data stored on the reduced interpolation frequency grid (reduce_data=True); such mode data is now accepted and its overlaps interpolated up to the requested frequencies.
• Fixed remote autograd gradients to reuse compatible cached forward results when possible and automatically rerun the forward simulation when partial cached data is missing or no longer usable for the backward pass.
• Transient (UnsteadyHeatAnalysis) heat simulations with only Neumann-type boundary conditions (e.g. all HeatFluxBC) are no longer incorrectly rejected; the all-Neumann check now applies only to steady-state simulations, where the solution is otherwise undefined up to a constant.
• Corrected the fixed-angle far-field projection phase so oblique fixed-angle sources with an off-origin center produce the right projected pattern.
• Fixed PolySlab adjoint derivatives to use winding-invariant sidewall sampling based on offset polygon slices.
• Fixed the Bloch phase application for DirectivityMonitor far fields, which was previously dropped at domain-edge cells in simulations with Bloch boundaries.
• Clarified the Job.step() and Batch.step() error message when workflow results are already complete, including from the local cache, and restored upload-time cost estimate logs for multi-step workflow jobs.
• Fixed seven default material models whose coefficients deviated from their reference data: Al 'Rakic1995' (real index was non-physical across the visible/NIR), Cr and Be 'Rakic1998BB', Au 'Olmon2012evaporated' (no interband response in the visible), Ag 'Rakic1998BB', and Pt and Ti 'Werner2009'. Validity ranges are unchanged; results change wherever these variants are used, explicitly or via the material default. For infrared-only simulations, the previous fewer-pole (lower-cost) coefficients remain available as 'Rakic1998BB_IR' (Cr, Be, Ag) and 'Olmon2012evaporated_IR' (Au) variants, restricted to the infrared bands where they match the reference data.
• Fixed a validation error caused by LossyMetalMedium mistakenly being added directly to the medium conversion of lumped elements.
• Fixed inline PyVista notebook plots sometimes failing to start interactive views.
• Fixed heat/charge meshing of abutting structures with finely tessellated (e.g. curved) boundaries, which could leave degenerate zero-volume elements that failed the solver's mesh check.
• Fixed Scene.plot_structures_eps() for unstructured custom-medium data with complex permittivities.
• Fixed flat BatchData result access for known skipped, failed, or incomplete batch tasks to raise a contextual DataError instead of a raw KeyError.

Removed

• Removed the deprecated conformal flag from heat-charge monitors (TemperatureMonitor, VolumeMeshMonitor, and the Steady* charge monitors). Monitor geometry no longer affects meshing: the simulation mesh is never forced to conform to a monitor. For value-producing monitors (temperature, potential, and the other Steady* fields), planar and line monitors now return values interpolated from the computational grid, while volumetric monitors return the grid cells contained in the monitor region. Files saved with older versions load unchanged, as the flag is dropped automatically on load.

Full Changelog: v2.12.0.dev2...v2.12.0.dev3