[w1ne]

Summary

Mate-axis explode (explodedPoses, used by render_preview, kernelcad render and drawing export) built its mate tree only from the first part. If the first part has no mates, the tree was empty and explode fell back to the declaration-order chain. Mated children in any other component received no offset.

The fix continues the BFS from the first part (in requested order, then declaration order) of each mated component the walk does not reach. Assemblies whose first part reaches every mate give the same result as before. This PR does not depend on #1385; that PR changes the mate solver, while this PR fixes the existing explode pose handoff.

Reproduction (real part)

KernelCAD's kernelcad-kinematic cookbook 05-clamshell-hinge-swept declares the unmated table first. With mate-axis explode at factor 1:

Code	Order	base offset (mm)	lid offset (mm)
develop	declared (table first)	[0, 0, 12] (moved off an unrelated part)	[0, 200, 6] (declaration chord)
develop	['base','lid','table']	[0, 0, 0]	[300, 0, 0] (hinge axis)
this PR	declared (table first)	[0, 0, 0]	[300, 0, 0] (hinge axis)

Regression test

tests/unit/modeling/explodedPoses.test.ts adds an unmated table before a fastened three-part stack. It asserts that table and base stay at zero offset, mid moves 10 mm in Z, and top moves 20 mm in Z. The case failed on develop, where base moved 10 mm.

Demo bundle

• 8-second MP4
• Poster
• Source, invocation, and verification notes

The MP4 is a labeled schematic of the passing test's exact offsets, not a renderer capture. A local CLI render capture did not open a tab or produce an image: the Node process waited in filesystem I/O and was interrupted. Mechanism status is unverified; the video makes no simulation, deployment, or hardware acceptance claim.

Verification

• npx vitest run tests/unit/modeling/explodedPoses.test.ts — 3/3 passed.
• npx tsx scripts/typecheckExamples.ts examples/exploded/clamshell-table-first.kcad.ts — passed, 1 file.
• Earlier local code checks recorded before the demo/docs commit: explodedPoses, renderCommand, and renderPreviewTool 52/52; tsc --noEmit clean; changed-source ESLint clean; quality ratchet 8/8. The original code-commit CI run passed all checks.
• The docs/demo commit passed all checks in GitHub CI run 43496975484; the final verification-note update also passed all checks in run 43498209792. The additional local ESLint attempt blocked in Linux filesystem I/O (D, folio_wait_bit_common) and was stopped without a result; CI lint passed.