Allow float64 roundoff in XRay detector parity checks

docs/xray/README.md

@@ -161,9 +161,13 @@ For Python A/B checks, pass `batch_rows=False` to
 `cuphoton.xray.detector_artifacts.build_detector_artifacts_cupy` to force
 the serial row loop. The default, `True`, batches eligible rows. The manifest
 records this choice, and serial runs have distinct configuration and resume
-identities. Frequency, amplitude, and FFT-frequency arrays match exactly in
-the batch-versus-row regression cases; `fft_all` can differ by rounding from
-the batched cuFFT plan (the normalized-trace tests use `atol=1e-15`).
+identities. Batch-versus-row regression checks preserve array shapes, dtypes,
+finite masks, zero padding, mode positions, fit status and FFT frequencies
+exactly. Fitted frequencies, amplitudes and filtered amplitude sums can differ
+by floating-point rounding, as can the batched cuFFT output. The normalized
+trace fixtures use `rtol=0`, with `atol=5e-15` for fitted outputs and
+`atol=1e-15` for `fft_all`; these bounds describe those fixtures rather than
+arbitrary input scales.
 
 `--fit-diagnostics summary` writes one status-aware record per detector row
 within each processed tile, covering the tile's `tile_x_start` to

tests/xray/test_detector_artifacts.py

@@ -1475,13 +1475,20 @@ def _assert_detector_outputs_match(
     expected: dict[str, np.ndarray],
 ) -> None:
     for name, values in expected.items():
-        if name == "fft_all":
-            # The batched cuFFT plan rounds differently from per-row FFTs.
+        assert actual[name].shape == values.shape
+        assert actual[name].dtype == values.dtype
+        if name in {"freq_all", "amp_all", "amp_all_sum_filtered", "fft_all"}:
+            np.testing.assert_array_equal(
+                np.isfinite(actual[name]), np.isfinite(values)
+            )
+            np.testing.assert_array_equal(actual[name] == 0, values == 0)
+            # Row and batched GPU arithmetic can round differently. Keep a
+            # fixed absolute error budget for these normalized fixtures.
             np.testing.assert_allclose(
                 actual[name],
                 values,
                 rtol=0.0,
-                atol=1e-15,
+                atol=1e-15 if name == "fft_all" else 5e-15,
             )
         else:
             np.testing.assert_array_equal(actual[name], values)