No blockers raised; residual cleanup:
- processor.py: guard int(doc_task.doc_id) with is_valid_nextcloud_doc_id in
the mail_message branch (consistent with search/context.py + the verifier).
- mail metadata symmetry: store `bcc` in file_metadata and the Qdrant payload
alongside cc (build_mail_content already emits a Bcc: line).
- server/mail.py: extract _cap_attachment_content helper (byte-accurate cap)
and unit-test it (small/None/oversized/multibyte).
- client/mail.py: give the synthetic OCS-error Response an explicit empty body;
add a test that a traversal-style attachment_id is percent-encoded.
- models/mail.py: clarify ListMessagesResponse.total_count is the page count,
not the mailbox total.
Deferred (Deck #376): _potentially_deleted doc_type-in-key. It's pre-existing
and spans ~30 sites across the notes/news/deck/file/mail scanners (whose
deletion paths have no unit coverage), so it belongs in its own focused PR
rather than expanding this mail PR's blast radius into other doc types.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
