Docmost duplicates block ids on copy/paste, and copyPageContent writes the
source document verbatim with the same ids. `patchNode`/`deleteNode` address a
block by `attrs.id` via replaceNodeById/deleteNodeById, which act on EVERY node
sharing the id — so a single patch_node/delete_node could silently
replace/remove multiple unrelated blocks with no signal to the model
(red-team finding #6).
Guard both write paths: when more than one node matches the id, skip the write
entirely (the transform returns null -> no mutation) and throw a clear
"ambiguous id — N nodes share it" error so the model re-targets with a more
specific anchor. Only an unambiguous single match is written; the 0-match and
1-match behavior is unchanged.
The duplicate-count basis is covered by node-ops.test.mjs (replaceNodeById /
deleteNodeById report count===2 for a 2-duplicate doc). The end-to-end guard
is not unit-tested because patchNode/deleteNode require a live collab provider
and the test suite has no provider mock.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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