Follow-up to #591, prompted by the update-check notice showing a raw
https:// URL as plain text instead of a clickable link. Made it general
rather than a one-off fix, since future announcements may also want to
link to docs.
Added Announcement.LinkText/LinkURL (+ LinkURLFunc, the dynamic
counterpart, for the update-check entry's per-release URL) alongside the
existing Message/MessageFunc pair. Both frontends render it as a real
<a> element now: the admin UI (innerHTML) escapes Message/LinkText/LinkURL
via the existing escapeHtml() before composing the markup — previously
Message went into innerHTML unescaped, which this incidentally hardens;
the player (Preact/htm) templates an actual <a> rather than interpolating
a string, since Preact escapes string children by default and a raw
<a href=...> string would otherwise render as literal text, not a link.
Rephrased the #419 admin-gate announcement to use the new field too (was
a plain "See issue #419 for details." text mention).
Bug found while wiring this up: UpdateCheckState never persisted the
release URL, only the version — so after a restart, the announcement
would show a correct message but a broken/empty link until the next live
check completed (which can be up to a full interval away, since a fresh
check is skipped when the persisted last-check is still recent). Fixed by
adding UpdateCheckState.LastReleaseURL and threading it through
Checker.persist/NewChecker's seeding path, with a test
(TestNewChecker_SeedsFromPersistedState) that would have caught it.
Also fixed two gocritic rangeValCopy findings in
handlers_announcements.go (switched to index-based iteration) surfaced by
the Announcement struct growing with the new fields.
Refs #591
Second piece of #591. Standalone package (pkg/service/updatecheck):
GitHub releases API client, golang.org/x/mod/semver comparison (promoted
from indirect to direct dependency), persisted state via datastore's
UpdateCheckState. Dev/(devel)/dirty current versions skip the comparison
entirely rather than guessing; prereleases are excluded even though
GitHub's /releases/latest endpoint shouldn't return one anyway (defensive).
Deliberately decoupled from handlers.Server/main.go: repo and current
version are constructor arguments, not hardcoded, so a future CLI-side
check could reuse this as a plain import rather than a rewrite (open
question 2 in the design doc).
Not wired into the service yet — nothing calls NewChecker/CheckNow outside
tests.
Refs #591
Tobias Gesellchen