To avoid old threads re-appearing on popular pages when someone
uses a vague title (e.g. dozens of threads titled "question" on
[[Wikipedia:Help desk]]: https://w.wiki/fbN), include the oldest
timestamp in the thread (i.e. date the thread was started) in the
heading ID.
Bug: T264478
Change-Id: If918bfd5e025248923d1939bc86916697ead95a0
Sequential numbers aren't great because they change when an earlier
comment is archived. Parent comment/heading IDs should change less
often.
This also makes much more sense for disambiguating subsections,
e.g. a dozen identical ===Votes=== sections for a dozen proposals.
Bug: T264478
Change-Id: I466454984fd919ebef35f2b37ddb5d86dc842996
Our threads now also contain all replies to their sub-threads.
This is similar to how sections work in MediaWiki, where the parent
section also contains the content of all the lower-level sections.
We're going to need this for notifications about replies in a thread.
Bug: T264478
Change-Id: I241fc58e2088a7555942824b0f184ed21e3a8b6f
Previously, only comments could have IDs, because we only needed IDs
for replying. But we might also use them for notifications soon.
Bug: T264478
Change-Id: I1bcad02bf17ab54bc5028a959543c10f0430836b
