fix(sdk): store and report one spelling of an upload's filename

[matej21]

Unicode lets the same filename be two different byte strings. macOS hands over the decomposed form — á as a + U+0301 — and that is what the uploads plugin wrote to disk and put in the <attachment filename="…"> tag it shows the agent. A model asked to use that name writes the composed form back, because that is what models produce. The two do not compare equal, so every path the agent builds from the name it was given misses the file that is actually there:

cp: cannot stat '…/uploads/<id>/Veronika Paulova'$'\303\241''_ucitelka.jpg': No such file or directory

Observed on a production session with Czech filenames: 21 of its 95 tool failures, second only to a path-resolution bug. There is nothing the agent can do about it — it never sees the bytes, and retrying produces the same string. It spent turns on ls, find and a second cp before giving up on the attachment entirely.

The fix

Compose on the way in, once, in prepareUpload. The stored name is carried on PreparedUpload, and both upload handlers now build their UploadDescriptor from that rather than from their own copy of the input — so the metadata, the attachment_uploaded event and the directory entry agree by construction instead of by coincidence.

Only the spelling changes. NFC cannot introduce a path separator, and validateUploadInput runs on the normalized name, so the basename check still guards what is written.

Verification

bun run ts:build clean. bun test packages/sdk/src/plugins/uploads/ 61 pass / 0 fail.

The new test fails without the fix (verified by neutering toStoredFilename), and the wider packages/sdk suite has an identical failure set on this branch and on main — 26 either way, all in services/skills/mailbox/agent-shutdown, none touched here.

🤖 Generated with Claude Code

https://claude.ai/code/session_01MjPDwksb3bAUC4fCVi3QXS