file_upload tool fails with "expected array, received undefined" for paths — persists after extension update and full reinstall-equivalent reset

Environment: Claude in Chrome extension v1.0.84 (confirmed current as of today), macOS, Cowork mode.

Steps to reproduce:

Navigate to any page with a file input (tested on a property-management web app's file upload).
Use find to locate the file input element.
Call file_upload with a valid paths array (e.g. ["/path/to/file.pdf"]), the correct ref, and the correct tabId.

Expected: File uploads via the located input.

Actual: Immediate validation error on every attempt:

Invalid arguments for tool file_upload: [{"expected":"array","code":"invalid_type","path":["paths"],"message":"Invalid input: expected array, received undefined"}]

The paths array is present and correctly formatted in the call, but the tool reports it as undefined.

What I've already ruled out:

Not a stale-session issue — reproduced identically both before and after a full Chrome quit/reopen.
Not an extension-cache issue — reproduced identically both before and after updating the extension from an older version to 1.0.84.
Not a source-folder permissions issue — reproduced identically using two different files in two different Cowork-connected folders.
6 total identical failures across these variations, 0 successes.

Notable: This exact tool worked correctly for the same kind of upload on the same site earlier in this same project — it's a regression, not something that was always broken.