Found while testing crates/engine/src/io.rs:183-187 (read_bytes, the "doc" | "dot" arm returns before opened() is called)
Co-authored-by: Claude Haiku 5.5 <noreply@anthropic.com>
A `DATE` or `TIME` field showed whatever was cached the last time the file was
saved, so a letter written from a template went out carrying the date the
template was saved. Word refreshes those two whenever it shows, prints or
exports a document; WordCraft only did so on an explicit Update Field(s), on
insert, or when printing with "Update fields before printing" on. Headless
`convert` to PDF was the worst of it: nothing hints the date is old.
Refresh them where a document is read instead, in a new `io::opened` beside
`ensure_nonempty` -- the two things a freshly-read document needs -- so `text`,
PDF, rendering and the window all show the same, current value. The model's
stored result is the one source they share; patching each output path would
have needed a clock in two places and still missed the next one.
Narrow on purpose. Only `DATE` and `TIME`: `CREATEDATE`, `SAVEDATE` and
`PRINTDATE` record when something happened and are not "now", and `REF`, `TOC`
and citations stay on explicit update, as in Word. A field carrying `w:fldLock`
keeps its stored result, which is what the lock is for. Headers, footers and
text boxes are covered too, not only the body.
The field code is untouched, so saving writes the field back as it was, with a
current cached result -- as Word writes one.
Co-authored-by: Brandon Thomas <echelon@gmail.com>
