This task involves the work with defining what people will experience when the software cannot be certain where the comment people are looking for is located. See the ===Cases below for the list of scenarios in which people might encounter this scenario.

Stories

• As someone who is trying to view a comment that the software cannot confidently locate and take me to, I want to know that the software cannot locate the comment I am seeking, why it cannot locate said comment, and where I might look to find said comment, so that I can: A) increase the chances that I can find the comment I'm seeking myself and B) form more accurate expectations for what the comment linking feature is and is not capable of.

Requirements

1. When someone arrives to a page after clicking/tapping a permalink and one of the following three things happens (see below); they ought to see a toast-like dialog
   1. The comment cannot be found
      1. Comment exists, but we can't find it. E.g. it didn't get indexed via T315510
      2. Comment never existed. E.g. the commentID is corrupted or otherwise invalid.
   2. The comment might be visible in more than one place
2. The "toast-like dialog" "1." describes ought to:
   1. Inform people which case (A, B, or C) they're experiencing
   2. Present people with action(s) they can take to locate the comment the software has not able to confidently locate
   3. Show a maximum of YET-TO-BE-DETERMINED NUMBER of potential pages on which the comment you're seeking could exist. In cases where the number of potential pages exceeds said "yet-to-be-determined-number" of pages people ought to see a call to action that invites them to visit Special:FindComment to see all results.

Mockups

Prototype

https://patchdemo.wmflabs.org/wikis/5ee978883e/wiki/Talk:Empty#c-Jts1882-2021-10-19T14:32:00.000Z-Medelam-2021-10-19T13:49:00.000Z

Open Questions

• 1. What are all of the cases we need to consider as part of this task?
  • See T304579#8097154.
• 2. How might someone generate a link to a comment before the permanent links feature gets deployed?
  • This was made possible by way of https://meta.wikimedia.org/w/index.php?title=User:ESanders_(WMF)/commentlinks.js
• 3. What would be involved with back-filling the data for older comments?
  • See: T315510
• 4. What – if anything – do we show if/when a plain fragment (T349653) doesn't match an archived section?
  • Note that fragments are used by other apps, e.g. "#/media/File:.." so although we try to filter out known patterns, we may end up searching for "headings" that aren't actually fragments for another purpose, e.g. #myApp-isOpen. Displaying a "topic not found" message in these cases could be confusing.
    • Conversely, not showing anything when the user follows a link to a thread that was deleted (not archived) could be confusing, when the equivalent DT permalinks do show "not found" messages.
    • Actual examples of gadgets setting the hash fragment to something other than a section title: https://global-search.toolforge.org/?q=location%5C.hash+*%5C%3D+*%5B%22%27%5D%5B%5E%22%27%5D&regex=1&namespaces=2%2C4%2C8&title=%28Gadgets-definition%7C.*%5C.%28js%7Ccss%7Cjson%29%29 .

Done

• Answers to all Open questions are documented
• Requirements are documented
• Mockups are added and implemented

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Cases

This section contains the list of cases we will need to design the user experience for; it is borrowed from what @matmarex has documented on mediawiki.org: Extension:DiscussionTools/How_it_works#Permanent_links.

Case #1: the comment might not visible anywhere

• Potential reasons:
  • The comment being linked to never existed in the first place, and the link is wrong
  • The comment being linked to has been removed from the page (removing comments outright is rare, but occasionally done for off-topic, redundant or offensive comments)
  • The comment being linked to has been edited in a way that breaks our identification (e.g. deleting and re-adding a signature)
  • The comment being linked to was supposed to be archived/moved by cut-and-paste, but something went wrong with the second half of the operation and it was just deleted
  • The discussion item database hasn't been populated for that page.

Case #2: the comment might be visible in more than one place

• Potential reasons:
  • The comment being linked to is actually two indistinguishable comments on different pages (read: two comments with the same author, date and time)
  • The comment being linked to was supposed to be archived/moved by cut-and-paste, but something went wrong with the first half of the operation and it was just copied
  • The comment being linked to might be transcluded on multiple pages (we ignore transclusions when looking for the redirect target, so this doesn't lead to the scenario below)

Case #3: the comment might be older than the permalinks feature
The feature only has data about comments added after it has been deployed.