feat(pick): show message times on the viewer's clock, not UTC

[Triyambak-CA]

The itch

The picker slices HH:MM straight out of the RFC 3339 stamp, so a transcript written in UTC is displayed in UTC with no zone marker. I am at +05:30, so every row reads five and a half hours in the past.

That is not just cosmetic, because the row shows a clock face and no date. A 19:53 from 27 July is indistinguishable from one from this evening. It cost me real time twice while debugging #53: I read a stale session as a live one, and chased the wrong explanation for several minutes before checking the transcript directly.

What changed

clock now moves the time to the machine's UTC offset.

Only a Z stamp is moved. One that already carries an offset (…+05:30) is local to whoever wrote it and is shown as written, so hosts that record local time are unaffected.

No date arithmetic is involved: crossing midnight changes the date, not the clock face, so this is (hh * 60 + mm + offset).rem_euclid(1440) and nothing more.

Where the offset comes from

std has no local-time API, and this crate deliberately carries no date dependency, so the offset comes from date +%z - the same shell-out idiom last::locate already uses - resolved once behind a OnceLock. Non-unix returns 0, and anything unparseable returns 0, so both keep exactly today's UTC behaviour rather than guessing.

If you would rather own a dependency for this, say so and I will switch it to jiff or time. I picked the zero-dependency version because of the note in Cargo.toml about keeping the build pure Rust, but it is your call and the change is small either way.

One existing test touched

the_picker_lists_newest_first_and_opens_the_chosen_message asserts on rendered times, which would otherwise vary by the machine running CI. The offset is held on App so that test pins it to 0 in one line and the assertions stay exactly as they were.

Tests

Three, in a tests module beside the code in pick.rs:

• a_utc_stamp_is_shown_on_the_local_clock - including a day rollover, 19:53Z at +05:30 is 01:23
• a_stamp_that_already_carries_an_offset_is_shown_as_written
• a_zone_string_reads_as_minutes_east_of_utc

cargo fmt --all --check, cargo clippy --workspace --all-targets and cargo test --workspace all clean on 1.97.1.

Deliberately not included

Showing a date for messages that are not from today. That needs real civil-date arithmetic, which is where a dependency genuinely starts to earn its place, and it would double the size of this diff. Happy to follow up if you want it.

[backnotprop]

Merged. The Z-only conversion guard, the zero-dependency offset with UTC fallback, and pinning the offset in tests made this an easy review. Ships in the next release.