[Jammy2211]

Summary

Fixes #739.

al.interop.coolest.to_coolest() wrote every template with an empty observation.pixels block (field_of_view_x/y = (0, 0), num_pix_x/y = 0) because it built lazy.Observation() with no pixel grid. COOLEST's plotting API cannot render such a template (ModelPlotter fails with IndexError); an external reviewer found this and confirmed that setting the grid so its pixel scale matches the instrument block makes plotting work.

to_coolest now writes a real PixelatedRegularGrid from shape_native + pixel_size, or directly from a dataset= (anything with shape_native and pixel_scales, e.g. an al.Imaging). If neither is given the template is written as before (zeros) and a UserWarning says COOLEST plotting needs the grid.

It also gains on_unsupported="skip" for models COOLEST has no analytic profile for (an MGE Basis of Gaussians, a pixelized source). The supported parts (full mass model, Sersic light) still export and every omitted component is recorded under meta.skipped_profiles as {"galaxy": "galaxy_i", "profile": "Basis(GaussianSph x 30)" | "Pixelization(Delaunay)"}. The default "raise" keeps today's behaviour, so existing callers and the workspace_test round trip are unchanged. This is what the Euclid DR1 pipeline (MGE lens light + Delaunay source) needs to write COOLEST by default; converting those components to COOLEST pixel grids is a follow-up.

API Changes

• to_coolest(...) gains keyword parameters shape_native=None, dataset=None, on_unsupported="raise" (inserted before metadata; all known callers pass metadata by keyword).
• New UserWarning when a template is written with no observation grid.
• Template meta may carry a skipped_profiles list when on_unsupported="skip".
  See full details below.

Test Plan

• pytest test_autolens/interop -q — 13 passed (6 existing + 7 new: grid from shape_native/pixel_size incl. pixel-size identity with the instrument block, dataset= path, no-grid warning with zeros, default raise on MGE + pixelized galaxy, skip records both and still exports SIE + shear, invalid on_unsupported, from_coolest on a skipped template returns the mass-only tracer).
• Hand check reproducing the report: a 100x100 / 0.1" template loads with JSONSerializer(...).load() giving num_pix_x == 100, field_of_view_x == (-5.0, 5.0), observation.check_consistency_with_instrument() passes, and coolest.api.plotting.ModelPlotter.plot_surface_brightness / plot_convergence render. The same model written without a grid reproduces the IndexError.
• autolens_workspace/scripts/guides/coolest_interop.py runs end to end with the new grid (round-trip max deflection difference 8.9e-16); workspace PR follows behind the library-first gate.

Full API Changes (for automation & release notes)

Removed

• none

Added

• autolens.interop.coolest.to_coolest(galaxies, file_path, cosmology=None, mode="MAP", pixel_size=0.1, shape_native=None, dataset=None, on_unsupported="raise", metadata=None) — shape_native=(y, x) with pixel_size, or dataset=, writes the observation.pixels grid (field_of_view_x = (-x*ps/2, x*ps/2), field_of_view_y = (-y*ps/2, y*ps/2), num_pix_x = x, num_pix_y = y); on_unsupported="skip" omits unconvertible profiles and lists them in meta.skipped_profiles.

Migration

• Before: al.interop.coolest.to_coolest(galaxies=tracer, file_path="model") → template with a zero observation grid (now warns).
• After: al.interop.coolest.to_coolest(galaxies=tracer, file_path="model", dataset=imaging) or shape_native=(100, 100), pixel_size=0.1.
• Models with MGE / pixelized components: add on_unsupported="skip" and read meta.skipped_profiles.

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[Jammy2211]

Workspace follow-ups behind the library-first gate (merge this PR first): PyAutoLabs/autolens_workspace#551, PyAutoLabs/euclid_strong_lens_modeling_pipeline#82. Heart RED override authorised by the human on 2026-09-16 for PR-open only; see #739.