Review of the offline drafts found these.
- Every new message gets new part ids and old ones die with it, so an
open composer failed with `blobNotFound` after a flush. The client and
the flush re-read the draft and re-point parts once. The fake now
gives new part ids, which is why `drafts.test.ts` and
`drafts-client.test.ts` compare file contents instead of blob ids.
- A Message-ID alone could destroy another client's message. A copy now
has to be solely in Drafts, with `$draft`, close to the attempt, with
the same subject and size, and what the lookup saw is the destroy's
base. Ghosts ride on the replacing row and only queue once it's up.
`drafts.created` no longer queues a copy that arrived for a replaced
row, so its test now expects the next flush to do it.
- Turning offline off asks about device-only drafts too.
- A kept file can't read back empty: chunks of a kept file are left
alone, and `keptBlob` and `heldFile` refuse pieces that don't add up.
- A flush stopped by a passing failure tries again, the banner shows
waiting drafts, and under the flush lock a `sending` row counts as
left by a dead tab at once. A lookup refused for good no longer stops
the outbox.
- `FetchTransport` streams downloads and reports a broken transfer as
interrupted, so one bad file doesn't end the pass.
- Raw messages come after every file, only into free room, and a file
needing room pushes them out first.
- An old version in another login stays until the new one is up. An
online send of an unflushed stand-in still removes its submission.
A draft saved offline now stays on the device under a stand-in id and
goes to the server by itself when it's back. Until now every save was
refused and the composer showed "not saved".
- `lib/store/drafts`: one pending create per draft, however often it's
saved. A draft from the server edited offline is replaced by create,
then destroy, so a failure leaves a copy. Each create has a fixed
Message-ID, looked up in Drafts after a lost response. A refused
draft stays on the device with its error and can be opened. Changed
on another device: both are kept and the user is told.
- `JMAPClient`: stand-in ids in Email/get and Email/set resolve like
calendar's, also when answering from the device. A file attached
offline stays readable, and is uploaded before a save that names it.
- Held files and kept mail files are stored in 1 MB chunks. Orphans are
dropped at the end of a flush, counting what drafts need.
- `lib/store/mail/attachments.ts`: attachments, inline images and raw
messages per scope, newest first, after everything else in a pass,
with eviction that spares pinned mail and never sees held files.
- `mail.rawBlob` and `mail.rawStatus` for an offline export.
Changed test assertions: `outbox.heldFile` and `mail.getBlob` return
`blob` instead of `data`, so a file isn't held whole in memory. The
attachment tests ignore raw downloads, and mail-sync runs with
attachments off, because raw messages add a commit per message.