Two pre-existing canvas test failures:
1. canvas/src/components/tabs/FilesTab/tree.ts:getIcon()
FILE_ICONS keys are lowercase (".json") but the extension was looked
up as-is (".JSON"). Result: FILE_ICONS[".JSON"] → undefined → fallback
"📄" instead of "{}".
Fix: lowercase the extension before FILE_ICONS lookup. Also added ?.
null-coalescing on split().pop() to handle filenames without extension.
2. canvas/src/store/__tests__/canvas-topology-pure.test.ts
sortParentsBeforeChildren test expectation was wrong: it assumed orphan
would come after root, but when parentId references a missing node
the orphan keeps its input order (orphan, then root). Updated the
expectation and corrected the comment to match the actual behaviour.
Closes#697.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
