List the timer unit files on disk, not only the loaded timers

[edimarlnx]

A timer written with c was invisible in the tool that wrote it.

c installs the .service and the .timer, runs daemon-reload, and does not enable the timer. systemd loads no unit that nothing references, so the new timer is in neither systemctl list-timers --all nor systemctl list-units --type=timer — the two lists this tool enumerated from. The timer was on disk, correct, verified, and had no row: nothing to select, so nothing to enable, run or delete either. Reproduced here on systemd 257:

$ systemctl --user list-timers --all | grep -c probe   # 0
$ systemctl --user list-units --type=timer --all | grep -c probe   # 0
$ systemctl --user list-unit-files --type=timer | grep probe
zz-probe-cron.timer          disabled disabled

What changed

• internal/timers: listTimers merges the loaded timers with systemctl list-unit-files --type=timer, loaded first and disk-only appended, so the order a reader knows does not move. Templates (name@.timer) and alias rows are dropped — neither is a unit systemctl show can be pointed at. The unit-file read is best-effort: if that systemctl refuses it, the loaded list is returned unchanged.
• internal/jobs (--demo): the sample machine had the same hole twice — BuildCreate never staged the unit files into the map the install hook reads, and an installed whole unit was recorded nowhere — so the demo created a timer and then showed nothing. It now keeps installed units and builds the row from them, the way the real backend reads them off disk. A deletion forgets them again.
• test/smoke.sh: the timer count was asserted against list-units alone, which any machine with an installed-but-disabled timer (fwupd-refresh.timer, typically) would now fail. It compares against the union of both lists.
• README: how the list is built and why both halves are needed.

No new mutation, no change to any command a confirm dialog shows. Deleting such a timer works unchanged: systemctl disable --now on a never-enabled unit exits 0.

Verified

• go test ./..., make lint clean; new unit tests for the unit-file parsing (real captures in internal/timers/testdata, including one of a freshly written timer), for the merge, a fuzz target, and an end-to-end demo test that creates a timer, finds the row, and deletes it.
• test/smoke.sh against this Fedora 42 host: 25 passed, 0 failed, timer count 17 on both sides.

🤖 Generated with Claude Code