# Differential-element verification

Validation against the final 1.7.0 checkout on 2026-09-30. CTAN submission and
publication status are recorded separately in `release-1.7.0.md`.

- All 15 regression suites pass. Generated reference and bundle freshness
  checks pass for 121 features.
- All 57 example documents compile (154 rendered pages) with the checkout
  forced through `TEXINPUTS`; each example has its own output directory.
- The isolated single-file runtime compiles eight module gallery documents
  and the six-page starter, using an empty user TeX tree. Recorders contain
  only the local bundled `tikzphysics.sty`, with no split physics libraries.
  Explicit meta/module/heattransfer alias requests also compile without
  loading system copies.
- All 17 module gallery pages are pixel-identical between split and isolated
  bundled runtimes at 72 dpi. Every sampled RGB pixel is monochrome.
- Every page of the thermodynamics, thermalphysics and elements galleries
  was visually inspected after the final runtime changes.
- Physical strokes inherit native TikZ line widths. A regression instrumenting
  actual PGF stroke calls verifies 1.25 pt document styling across mechanics,
  surfaces, ramps, optics, differential elements, fluids, thermodynamics and
  thermalphysics. No physical runtime imposes a custom stroke width; debug
  annotation leader lines retain their independent diagnostic styling.
- Overleaf archive integrity and the contents of all 20 files are checked.

Evidence: `tmp/release-1.7.0/` (compile recorders, raster comparisons, visual
renders, complete test output and independent loading probes).

Element fixtures contain 57 existing polar PASS records, 23 solid-element
records (including both x and y in point comparisons), and 81 new review
records. The added fixture checks all integer families on nine native nodes,
all 13 new projected pic families, independently calculated large-radius and
narrow-angle centroids, mixed units and transformations, axial endpoints,
unequal cone slice radii, ellipse interior points and instance isolation.
All 18 invalid-input cases produce the intended package diagnostic.

The four element PDFs contain six visually reviewed pages: original circular,
solid and font/material galleries plus three new percentage/styling pages.
Fixed the reproducible 3 cm polar-centroid overflow using normalized radii;
small-angle sinc uses a stable limit. Corrected vertical sphere-disk hidden
edges, cylinder-shell physical height, and native element text centring.
Added actual projected rim and axial percentage coordinates, preserving named
components and existing family directions. Label leaders in the new gallery
prevent crowded percentage annotations.

Full-circle compass anchors are placement bounds; rim families locate actual
material curves. Highlighted finite-thickness slices and unwrapped rings
illustrate differential approximations, not exact finite-volume solvers.