[BUG] Reordering the choice list deletes any choice the render filter dropped

[chhoumann]

Found while fixing #1593, deliberately not grown into that PR: the same class of bug, on the choice list rather than the command list, and a live data-loss path on master.

The shape

ChoiceList.svelte:62-66 filters the rendered list to entries that can be keyed:

const renderable = $derived(
    rootChoicesOf(choices).filter(
        (choice) => isChoiceLike(choice) && typeof choice.id === "string" && choice.id !== "",
    ),
);

The comment above it (:58-61) says this is a "Render-time view only. Nothing here rewrites the tree." That is not true, because renderable is also what seeds the drop zone (:152) and what the persist path commits:

• :152 use:dndzone={baseDndOptions({items: renderable, ...})}
• :110 choices = next (from stripShadow(e.detail.items))
• :114 actions.onReorderChoices(choices)
• :133 moveChoice does the same from stripShadow(renderable)
• ChoiceView.svelte:328-331 -> save() -> :101-103 saveChoices(snapshot(choices))

So the first drag or ArrowDown persists the filtered list, and every entry the filter dropped is gone from data.json.

Why it matters

For a null hole this is harmless - it carries nothing. But the filter also drops any entry whose id is not a non-empty string, and

{ "name": "Daily note", "type": "Template", "templatePath": "Templates/Daily.md", "format": {...}, "id": 12 }

is a complete, working choice whose id was written as a JSON number by a bad hand-edit, a script, or a merge. It is invisible in the settings list, so the user cannot miss it - and one reorder deletes it, with no prompt and no undo. That undoes exactly what dedupeChoicesById (choiceUtils.ts:218-221) goes out of its way to preserve.

The second half of the comment is wrong for the same reason: "It cannot be hiding a choice - only a Multi's choices value can" is false, because :64 drops id-less entries that are otherwise whole choices.

Suggested shape

Two options, in order of preference:

1. Mirror what [BUG] A macro's commands has no read-accessor guard, so a malformed one is unrecoverable through the UI #1593 shipped for commands: repair rather than hide. A choice with a missing/non-string/duplicate id gets a fresh uuid at the seam and stays visible, so the user can see and delete it. dedupeChoicesById already does the duplicate half at load; this is the missing/non-string half.
2. Failing that, reconcile the persist back onto the raw array (the setFolderChildrenById by-id idiom, choiceService.ts:589-635) so a reorder can only reorder, never delete.

Either way ChoiceView.malformed.test.ts needs the missing ratchet: reorder a list containing a hole and an id-less choice, and assert the persisted array is byte-identical apart from the reorder.

Related

• [BUG] A macro's commands has no read-accessor guard, so a malformed one is unrecoverable through the UI #1593 - the same bug for macro.commands, and where this was found
• [BUG] A malformed folder in data.json blanks the whole settings tab #1566 / fix: a malformed folder in data.json no longer takes the plugin down with it #1583 - the accessor split this list already uses for reads
• [BUG] Corrupted data file between quickadd versions #1451 - the original each_key_duplicate crash