Affected Repositories

• PyAutoArray (primary, library-only — no workspace follow-up)

Branch Survey

No worktree claims; worktree_check_conflict returned clean.

Suggested branch: feature/mask1d-shape-native-scalar-widening

Site 1 — Mask1D.__init__ never routes through the chokepoint

autoarray/mask/mask_1d.py:71:

if type(pixel_scales) is float:
    pixel_scales = (pixel_scales,)

Confirmed on main:

aa.Mask1D(mask=np.array([False, False, True]), pixel_scales=1).pixel_scales
    ->  1                    # bare int, not (1.0,)
...that mask's .geometry.scaled_maxima
    ->  TypeError: 'int' object is not subscriptable

Mask2D.__init__ is unaffected — it calls geometry_util.convert_pixel_scales_2d at
autoarray/mask/mask_2d.py:218. Grid1D.uniform is fine for the same reason. So this is
a 1D/2D divergence, not a design choice.

Replace the hand-rolled widening with the call Mask2D makes, keeping its current position
(after invert handling, before the len(mask.shape) guard) so ordering is unchanged:

pixel_scales = geometry_util.convert_pixel_scales_1d(pixel_scales=pixel_scales)

Behaviour change to state in the PR, not suppress: convert_pixel_scales_1d runs
validate.validate_pixel_scales first, so Mask1D starts rejecting 0, negative and nan
pixel scales — exactly as Mask2D already does. No test in test_autoarray constructs a
Mask1D with such a value, and the 12 library call sites all pass real scales, but any
failure this produces must be read rather than adjusted away.

Site 2 — convert_shape_native_1d keeps an exact-type check

autoarray/geometry/geometry_util.py:27 still has type(shape_native) is int. Reachable
through Array1D.full / zeros / ones, whose sole call site is
autoarray/structures/arrays/uniform_1d.py:143 and which then does shape_native[0]:

aa.Array1D.full(fill_value=1.0, shape_native=np.int32(5))
    ->  IndexError: invalid index to scalar variable

is_concrete_scalar is the wrong predicate here — shape_native is a pixel count, so
a float must not be silently widened. Use an integer-only test excluding bool, and cast
to int so the result matches the Tuple[int] annotation. Add it as is_concrete_integer
in autoarray/validate.py beside is_concrete_scalar (validate.py:48).

Update the docstring to match, mirroring the wording 8298d74e gave convert_pixel_scales_1d.

Do not add validate.validate_shape_native here — the function performs no validation
today and adding it is a separate change.

Explicitly out of scope

Tuple entries are still returned unnormalised: convert_pixel_scales_2d((1, 1)) → (1, 1),
contradicting the Tuple[float, float] annotation. It changes return values on paths that
currently work, so it needs its own change and its own suite read.

Tests

Mirror the naming convention 8298d74e established
(test__convert_pixel_scales_1d__widens_any_real_scalar).

• test_autoarray/geometry/test_geometry_util.py — convert_shape_native_1d widens int
  and np.integer to (int,) with a Python int entry; a bool is not widened; a (5,)
  tuple is returned unchanged.
• test_autoarray/mask/test_mask_1d.py — Mask1D(mask=…, pixel_scales=1) gives
  (1.0,), likewise np.float64(1.0) and np.int32(1); .geometry.scaled_maxima no
  longer raises; a (1.0,) tuple is unchanged; ValueError on 0 / -1 / nan; a JAX
  tracer still passes through untouched so Mask1D stays jit-safe.
• End-to-end: Array1D.full(fill_value=1.0, shape_native=np.int32(5)) builds.

Every new test must be confirmed to fail without the source change.

Verification

PYAUTO_SKIP_WORKSPACE_VERSION_CHECK=1 NUMBA_CACHE_DIR=/tmp/numba_cache \
MPLCONFIGDIR=/tmp/matplotlib PYAUTO_DISABLE_JAX=1 \
python -m pytest test_autoarray -q

Full suite, not just the touched files. Baseline the known pre-existing pynufft failures in
test_transformer.py by re-running them on a clean tree and comparing counts; 8298d74e
recorded 1145 passed / 1 skipped / 3 failed. Read any new failure rather than adjusting
the test. Then a JAX-enabled pass for the tracer case.

Key Files

• autoarray/mask/mask_1d.py — site 1, the hand-rolled widening at line 71
• autoarray/geometry/geometry_util.py — site 2, convert_shape_native_1d at line 27
• autoarray/validate.py — home of is_concrete_scalar; add is_concrete_integer
• autoarray/mask/mask_2d.py:218 — the pattern site 1 mirrors
• autoarray/structures/arrays/uniform_1d.py:143 — sole caller of convert_shape_native_1d
• test_autoarray/geometry/test_geometry_util.py, test_autoarray/mask/test_mask_1d.py

Scalar widening: the two sites the pixel_scales sweep did not reach

Type: bug
Target: autoarray
Repos:

• @PyAutoArray
  Difficulty: small
  Autonomy: supervised
  Priority: medium
  Status: draft
  Filed: 2026-08-23

Why this exists

PyAutoArray#464 (8298d74e, 2026-08-22) fixed convert_pixel_scales_1d and
convert_pixel_scales_2d: type(x) is float became validate.is_concrete_scalar,
so int, np.integer and np.floating are all widened and cast to float.

Re-running that prompt's repro on 2026-08-23 found the sweep did not reach every site.
Two defects of the same class are live on main. Both are confirmed, not suspected.
Completion record: complete/2026/08/autoarray-pixel-scales-scalar-widening.md.

Site 1 — Mask1D.__init__ never routes through the chokepoint

autoarray/mask/mask_1d.py:71 still carries the original exact-type check and does its
own widening rather than calling convert_pixel_scales_1d:

if type(pixel_scales) is float:
    pixel_scales = (pixel_scales,)

aa.Mask1D(mask=np.array([False, False, True]), pixel_scales=1).pixel_scales
    ->  1                    # bare int, not (1.0,)
...that mask's .geometry.scaled_maxima
    ->  TypeError: 'int' object is not subscriptable

This is #464's exact reported symptom, on a public constructor. Mask2D.__init__
is unaffected — it calls geometry_util.convert_pixel_scales_2d at
autoarray/mask/mask_2d.py:218. So this is a 1D/2D divergence, not a design choice,
and Grid1D.uniform is fine because it goes through geometry_util.

Fix: replace the hand-rolled widening with the call Mask2D makes:

pixel_scales = geometry_util.convert_pixel_scales_1d(pixel_scales=pixel_scales)

Consequence to state, not suppress: convert_pixel_scales_1d runs
validate.validate_pixel_scales first, so Mask1D starts rejecting 0, negative and
nan pixel scales — exactly as Mask2D already does. No test in test_autoarray
constructs a Mask1D with such a value, and the 12 library call sites all pass real
scales, but read any failure this produces rather than adjusting the test.

Site 2 — convert_shape_native_1d keeps type(x) is int

autoarray/geometry/geometry_util.py:27. 8298d74e listed this as not-fixed-here.
Reachable through Array1D.full / zeros / ones, whose sole call site is
autoarray/structures/arrays/uniform_1d.py:143 and which then does shape_native[0]:

aa.Array1D.full(fill_value=1.0, shape_native=np.int32(5))
    ->  IndexError: invalid index to scalar variable

Fix: widen to an integer-only test — is_concrete_scalar is the wrong predicate
here, since shape_native is a pixel count and a float must not be silently widened.
Use isinstance(x, (int, np.integer)) and not isinstance(x, bool), cast to int so the
result matches the Tuple[int] annotation. Prefer adding this as is_concrete_integer
in autoarray/validate.py beside is_concrete_scalar (validate.py:48), so the
function delegates its predicate the way its convert_pixel_scales_* siblings do.

Do not add validate.validate_shape_native here — the function performs no
validation today and adding it is a separate change.

Explicitly out of scope

Tuple entries are still returned unnormalised: convert_pixel_scales_2d((1, 1)) → (1, 1),
contradicting the Tuple[float, float] annotation. This changes return values on paths
that currently work, so it needs its own change and its own suite read. Unfiled.

Verification

• Mask1D(mask=…, pixel_scales=1).pixel_scales == (1.0,); same for np.float64(1.0)
  and np.int32(1); .geometry.scaled_maxima no longer raises.
• A (1.0,) tuple is returned unchanged; a JAX tracer still passes through untouched,
  so Mask1D stays jit-safe.
• Mask1D raises ValueError on pixel_scales of 0, -1 and nan, matching Mask2D.
• convert_shape_native_1d widens int and np.integer to (int,) with a Python int
  entry; a bool is not widened; a (5,) tuple is unchanged.
• Array1D.full(fill_value=1.0, shape_native=np.int32(5)) builds.
• Every new test confirmed to fail without the source change.
• Full test_autoarray suite, not just the touched files — site 1 changes the Mask1D
  contract. Baseline the known pre-existing pynufft failures in test_transformer.py
  against a clean tree; 8298d74e recorded 1145 passed / 1 skipped / 3 failed.

Repro environment: PYAUTO_SKIP_WORKSPACE_VERSION_CHECK=1,
NUMBA_CACHE_DIR=/tmp/numba_cache, MPLCONFIGDIR=/tmp/matplotlib,
PYAUTO_DISABLE_JAX=1.

Provenance

• Follow-up of: complete/2026/08/autoarray-pixel-scales-scalar-widening.md (PyAutoArray#464)
• Grandparent: complete/2026/08/autoarray-input-validation-guards.md (PyAutoArray#440 / Missing input validation across Array2D, Grid2D, Mask2D, Imaging, regularization #333)
• Not part of the @rhayes777 audit campaign (planned.md § rhayes-audit-validation-phases-2-4).