Implement dragging to reorder Properties panel node sections

[Keavon]

Recording.2026-07-01.030232.mp4

[gemini-code-assist]

Code Review

This pull request introduces interactive drag-and-drop reordering for Properties panel sections, allowing users to rearrange pinned nodes or nodes within a selected layer's chain. The changes span the frontend Svelte components, WASM wrapper, and backend Rust message handlers and network interfaces. Feedback on the changes highlights two key issues in the frontend drag implementation: a usability bug where aborted drags incorrectly swallow the subsequent legitimate left click, and a missing defensive check for when a dragged section is no longer found in the DOM (i.e., fromIndex is -1).

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[cubic-dev-ai]

6 issues found across 9 files

Confidence score: 3/5

• In frontend/src/components/panels/Properties.svelte, the drag-start button filter is too strict, so valid drags can be blocked when the reorder handle is not a <button>, which can make section reordering appear broken to users — broaden the guard to recognize the actual drag handle instead of button-only starts before merging.
• In frontend/src/components/panels/Properties.svelte, drag state/index handling has edge-case regressions (justFinishedDrag on Escape and missing fromIndex !== -1 guard) that can swallow the next real click or run reorder logic with an invalid index during concurrent UI updates — only set the click-suppression flag on completed drags and add an explicit fromIndex validity check.
• In editor/src/messages/portfolio/document/document_message_handler.rs, mixed selections can still enter the single-layer reorder path and trigger chain-node reordering incorrectly, risking unintended document edits — require that no non-layer selections are present before taking that path.
• In editor/src/messages/portfolio/document/utility_types/network_interface.rs, pinned-order pruning uses attempted deletions rather than successful deletions, so a failed delete can silently corrupt pinned display order for remaining nodes; the related recoverable path also logs at error level, which can hide real failures in noise — prune only on confirmed deletions and downgrade that log to warn/debug.

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