This fork is for test-integration of various fixes people have worked out to get this working in phpBB 3.3.5 and later. It is not ready to use on public/production sites if this note is still present here. It is not tested with 3.5.13 and later, nor with 3.3.4 or earlier.

Topic Tags 3.0.2

phpBB 3.3.x extension (expected to be compatible with at least 3.3.5 through 3.3.12), that adds the ability to tag topics with keywords.

Some configuration required! Please read the documentation carefully. This is not a fire-and-forget extension and will not work properly without some quick configuration steps.

Features

Common

• add tags when posting a new topic
• tag suggestions based on existing tags
• edit tags when editing first post of topic
• SEO: tags are added to meta-content keywords in viewtopic
• tags are shown in viewforum (can be disabled in ACP)
• enable tagging of topics on a per-forum basis
• responsive layout
• full UTF-8 support

Search

• search topics by tag(s)
• /tag/{tags}/{boolean}/{case-sensitivity} shows topics tagged with all (boolean = AND, the default) or any (boolean = OR) of the given tags, where tags are comma separated tags and case-sensitivity can be true to search case-sensitive or false (the default), e.g.:
• /tag/tag1,tag2/OR lists topics that are tagged with tag1 OR tag2 OR tAG2
• /tag/tag1,tag2/AND lists topics that are tagged with [tag1 AND (tag2 OR tAG2)]
• /tag/tag1,tag2 lists topics that are tagged with [tag1 AND (tag2 OR tAG2)] (boolean=default=AND, case-sensitivity=default=false)
• /tag/tag1,tAG2/AND/true lists topics that are tagged with (tag1 AND tAG2, but will not match tag2)
• tags are essentially case-insensitive by default (if you create a tag "foo", then "Foo" or "FOO" or "fOO" will be the same tag); the case-sensitivity search feature is primarily of use for finding tags that are inappropriately upper-case ("Dogs") or inappropriately lower-case ("europe") in their database-registered form.

Tag-Cloud

• /tags (plural) shows a tag cloud
• ACP option for tag cloud to be displayed on the board index page or not
• ACP option to limit count of tags shown in tag cloud on the index page
• dynamic tag-size in tag cloud depending on its usage count
• ACP option to also enable/disable display of tags' numeric usage counts in tag cloud

Advanced configuration

• configure a regex to decide which tags are valid and which are not
• maintenance functions in ACP > Extensions > RH Topic Tags
• tag whitelist
• tag blacklist
• user and mod+admin permissions for who can add/edit tags
• spaces in tags are converted to "-" by default (you can disable that in ACP)
• manage existing tags in ACP
• delete tag
• rename tag
• merge tags (rename one tag to the same name as another tag and they will automatically be merged)

Compatibility

This extension is known-working in phpBB 3.3.5, and refines code working up to at least phpBB 3.3.12. It may work in earlier or later 3.3.x versions, but has not been tested in them. This is coded with a "soft dependency" on 3.3.5. If you want to try it in an earlier version and can't despite "softness" of that requirement, just change 3.3.5 to 3.3 in the extension's composer.json.

Installation

In the instructions that follow, the directory ext/ means the phpBB extensions folder under whatever server directory path you used for your phpBB installation. Depending on what version you have and how you instsalled, it might be at the same level as your main phpBB installation directory instead of inside it. E.g., if most of phpBB is at /var/httpd/webdocs/phpbb/ your extensions might be in /var/httpd/webdocs/ext/ instead of /var/httpd/webdocs/phpbb/ext/. And the path to your website's files is going to vary widely from system to system, and could be something like /home/admin/web/yoursitename.com/public_html/phpBB/ or /serv/web/public/yoursitename/production/phpbb3/ or /home/yourusername/public_html/phpbb/. So, check first and adjust the instructions below to compensate.

1. Clone

Clone (or download and move/upload) the repository into a subdirectory of your phpBB extensions directory, as: ext/robertheim/topictags:

cd ext/
git clone https://github.com/SMcCandlish/phpbb-ext-topictags.git robertheim/topictags/

We are using the original robertheim/ path name because most of the code is his, and you cannot run this copy and the origial by RH at the same time, so there's no reason not to directly replace the original.

This folder structure is important; do not try something like ext/topictags/; that will not work, as all extensions have to be subcategorized by a developer name.

2. Activate

Log into your board. Go to ACP (Admin Control Panel) and login again as an admin. Go next to tab Customise > Manage extensions > enable RH Topic Tags

Go to ACP > tab Forums, and edit any forum (or create a test one); click the green gear icon to edit the forum, and under General forum settings set "Enable RH Topic Tags" to Yes; submit the changes with the button at the bottom of the page.

2.5. Purge phpBB cache

Depending on your phpBB version, you may find a "Purge the cache" option at AGP > Admin Index (which is at top right of the AGP window, or click tab General to get to same page). Otherwise, you may find a "Purge cache" option in the left menu at AGP > General. If you do not, you might have to login to your server via FTP/FTPS/SFTP/SSH, and delete the contents of phpbb/cache/ except for index.htm and .htaccess. If you find no such files there and instead find a driver/ subdirectory and a service.php file, then delete nothing (you have a different version of phpBB).

3. Configure

Go to ACP > tab Extensions > RH Topic Tags.

One important thing to check for and fix: at ACP > Extensions > RH Topic Tags > Settings > Tag settings, look in the regex field for "Regular Expression for allowed tags:", and if you see \\s change it to \s, and same with any other other cases of \\ which must be changed to \. By default, these will be \\p → \p, \\s → \s, and \\- → \-. There seems to be a "translation" problem somewhere between PHP, JS, and SQL that is extra-escaping \ and turning it into \\, which will break our character-matching intentions. Special case exception: if you customized the regex in any /robertheim/topictags/language/xx/topictags_acp.php file to explicitly permit the \ character in tags, that would have been coded as \\, which in this field may show up as \\\\ or \\\ and needs to be changed back to \\. Special case 2: If you attempted to permit / (perhaps as \/), this must be removed because the delimiter between tags in the database is / (no tag itself can contain /). Likewise, you must not permit , (including as \,) because that character is used as the delimiter by the https://yoursite.com/tag/tag1,tag2 search functionality.

For some tips on customizing your regex, see the comments inside /robertheim/topictags/language/en/topictags_acp.php (or the es, fr, or ru version).

When done, submit the changes with the button at the bottom of the page.

4. Test

Go to a forum in which you have enabled tags. Create a new test post in it (starting a new topic), and you should see a tags instructional line about the allowed characters, and below this a text-entry form field for tags. Try adding some (you might want to use real ones you intend for future use instead of test strings, so you don't need to delete them from the available tags later). Save the post, and see how it is tagged. Optionally try editing the top post of an existing topic, and you should be able to add tags to it. Now re-edit a post with tags and try changing them. Next, at the bottom of your board's front page you should see a tag cloud list that includes the new tags you just created (unless you turned off that feature, in which case go to https://yoursitename.com/tags to see the tag cloud).

Back at ACP > Extensions > RH Topic Tags > Manage Tags, you should be able to change the text of or delete any of these tags. Deleting one removes it from any post that had it.

A point of confusion to look out for: A topic's tags are shown on the first post of the top of every page of posts in the topic, but can only be edited in the first post in the entire topic, not the first post in a subsequent page of posts.

4.5 Troubleshooting

If the extension does not work for you, make sure you purged the cache. Next, check that the forum you are trying to use it in has permissions set to use this extension (either individually in that forum's configuration, or by turning on the feature everywhere (ACP > tab Extensions > RH Topic Tags > Settings > Configuration > Enable RH Topic Tags in all forums). Failing that, ensure that the filesystem permissions on the extension's files are correct (must be readable by whatever operating-system user the webserver runs as, and/or by its group). And ensure that the path to it is correct, at ext/robertheim/topictags/ in your phpBB setup, not at something like ext/topictags/.

If you are using phpBB 3.3.8 or later, and it is not working properly for you, perhaps try the following:

• Disable the extension.
• In ext/robertheim/topictags/acp/, rename white_and_blacklist_controller.php to white_and_blacklist_controller_BAK.php then rename white_and_blacklist_controller_ALT.php to white_and_blacklist_controller.php
• Purge the cache.
• Enable the extension again.

If it still doesn't work, try also this:

• Disable the extension.
• In ext/robertheim/topictags/event/, rename main_listener.php to main_listener_BAK.php then rename main_listener_ALT.php to main_listener.php
• Purge the cache again.
• Enable the extension again.

If it still doesn't work, reverse the first change but leave the second, and purge the cache again.

If it still doesn't work, undo both steps, and see if any recent-ish communication at https://www.phpbb.com/customise/db/extension/rh_topic_tags/support addresses the issue yet. When reporting an issue, be as specific as possible; no one can read your mind, or your logs.

Both of the above alleged fixes are dubious, as they are from a 2022 third-party attempt at phpBB 3.3.8 compatibility but based on RH's old branch for phpBB 3.1.x instead of the master (for phpBB 3.3.x). Someone later, working toward phpBB 3.3.9 compatibility, reverted the first of the above changes but kept the second (and cleaned up some of the directory structure). Another, for phpBB 3.3.9, reverted both (without the directory cleanup), and their change was accepted into RH's main branch, with others reporting it working with versions as late as phpBB 3.3.12. Someone later yet, for phpBB 3.3.10, also reverted both of the above changes in their own fork, but kept the cleaned-up directory structure. This version takes the last of these approaches, and goes further.

5. Customizing for themes

The default bright colors and white form-field backgrounds in this extension do not play nice with dark themes (you're especially likely to get unreadable light tag text on an also-light tag background).

If your site uses a dark theme, and that's the only theme available, then you could just change the CSS to suit your needs. This can be quite a hassle due to the complexity of the CSS, but it is doable with some patience; the developer Inspector/Console mode in your browser should help (usually accessed with Ctrl-Shift-I, or Cmd-Shift-I on a Mac). Just remember that you have to purge the cache before testing each change. Howeover, going this route makes your changes vulnerable to overwriting if the extension is updated later. It is better to create a CSS file for your specific theme(s), as described next.

If your site has multiple themes and one or more of them are dark, then what to do for each such theme is copy and modify a key CSS file. Using a example theme named MyDarkTheme the files for which go in a styles/mydarktheme/ directory and subdirectories thereof, you want to copy ext/robertheim/topictags/styles/all/theme/rh_topictags.css to ext/robertheim/topictags/styles/mydarktheme/theme/rh_topictags.css. Near the top of it (after the opening comment), add the following lines (with colors that suit your needs):

div.tags
{
	background-color:	#000;
}

.ng-valid
{
    background-color:	#323D43;
}

.tag-item
{
	color:	#97AAAF;
}

Then adjust whatever other colors you need.

A sample styles/mydarktheme/theme/rh_topictags.css is provided in this package, with the above already done and some other colors integrated to go along with that. You can simply copy or move that rh_topictags.css file into your actual dark theme's theme/ directory, see how it looks, and make adjustments from there.

Tip: This extension's default behavior is to have tags show with a particular background color in most circumstances, but change to a very different background color (and text color) when hovered-over if (but only if) you are editing the post and its tags. This can be problematic, in any theme other than the ProSilver this was designed for. The background color(s) of a tag have to work with at least four (up to six) different text colors: the tag as shown on a post when editing it; the same when hovering over it (by default, the extension changes the background color here, and only here); the linked tag as shown on a post when reading it (using your theme's default link color); and same when hovering over it (with your theme's default hovered-link color); you might also have a visited link color and a short-lived active link color (when the link was just now clicked). It is very difficult to arrive at two different background colors that work well with this array of text colors. Thus, it is most sensible to use a single background color for all of these purposes (override the extension's behavior of changing that color when hovering in edit mode); make it one that works with your site's default link colors, and then just use a grey or grey-ish "tag as shown on a post when editing it" text color, and a white or white-ish text when hovering over that (or black or black-ish text if the background is light), with the grey/grey-ish text color being fairly close to but distinct from your default link color, so that the text in every circumstance is legible on this background.

Depending on what you've done with your sites's default theme and any light themes, some tweaks in this regard might be needed for any/all of them.

Updating to a newer version

Make backups of any files you have modified, e.g. .css files for custom colors, and any language/en/topictags_acp.php files modified for particular sets of permissible characters in tags (which is better done in the ACP section for configuring RH Topic Tags). You may need to manually merge such changes back into the extension after upgrading it.

Go to ACP > tab Customise > Manage extensions > disable RH Topic Tags.

If you are upgrading to a newer version of the SMcCandlish fork already installed via git earlier (see way above), just do this:

cd ext/robertheim/topictags/
git pull

Or download it to your local computer and copy the files over by FTP, SCP, or whatever means you use for this purpose.

If you are upgrading from an old version that has an ext/robertheim/topictags/styles/all/angular/ directory inside it, the entire extension needs to be deleted, e.g. with:

cd ext/robertheim/
rm -rf topictags

Then re-download the current version (while still in the ext/robertheim/ directory) with:

git clone https://github.com/SMcCandlish/phpbb-ext-topictags.git topictags/

(or download it to your local computer and copy the files over by FTP, SCP, or whatever means you use for this purpose).

Either way, now go to ACP > tab Customise > Manage extensions > enable RH Topic Tags.

Then purge the cache again as described above.

If you were already using an old version prior to RH Topic Tags v3.0.2, then the permitted-characters regex and the description of it will be "baked into" your phpBB database already, and may not agree with what is in the current appropriate language/xx/topictags_acp.php file. What the new defaults are will be shown in ACP > tab Extensions > RH Topic Tags > Settings, to the left of the form fields for changing them. (Even if you already have a customized regex, it's worth reading the comment notes in that language file anyway, so you can be fully informed about your choices.)

Support

https://www.phpbb.com/community/viewtopic.php?f=456&t=2263616

Credits

• RobertHeim @ Github.com, for the original extension. RH's development of it appears to have ceased in 2020, even with regard to accepting others' pull requests (thus this fork).
• pierrdu @ phpBB.com forum, for phpBB 3.3+ Symfony upgrade patches to routing.yml and services.yml (already integrated into RobertHeim's master branch by the time I cloned it).
• sanekplus, thegioiluatsu, Naguissa, bonnp @ phpBB.com, for approaches to getting the Topic Tags version for phpBB 3.2 to work in 3.3+; while their changes were ultimately undone and the issue resolved a different way, what they tried was constructive in helping identify what the underlying problems were.
• zipurman @ phpBB.com, and Dark❶ @ phpBB.com (Dark1z @ Github), for a phpBB 3.3.8+ permissions fix to main_listener.php.
• Marc @ phpBB.com, for documenting phpBB 3.3.9+ changes in Twig behavior that require things like INCLUDECSS @robertheim_topictags/rh_topictags.css with the @dev_extension syntax instead of a relative path. While these changes were already integrated into RH's master codebase at the time of this fork, it has been relevant information in weeding through prior attempts to update the behavior of this extension, and helped later in resolving issues with @rogterheim_topictags/dir/../file.ext paths that had to change to not use /../ syntax.
• TJK @ phpBB.com, for further suggestions toward php3.3.8+ compatibility.
• dimassamid, Lord Phobos & SANSI @ phpBB.com, for further suggestions toward php3.3.9+ compatibility, especially the /../ paths no longer working.
• mi1eurista @ Github, for integrating several of the above tweaks into a single patch (which RH never got around to integrating).
• andrigamerita & Fantabulum @ Github, for confirming functionality in phpBB 3.3.10 and 3.3.12.
• iandoug @ phpBB.com, for figuring out where the regex stuff is to control what characters are permitted in tags.
• combuster @ phpBB.com, for documenting that the phpBB cache has to be cleared or malfunctions will occur.

Change log for 3.0.2

• Updated README.md to account for all of the below, and to just read better.
• Fixed the stupendous security/privacy problem of the tag cloud being visible (in two different ways) to non-logged-in visitors. Various sites could be using this software for sensitive information, especially in an intranet circumstance (client names, internal project code-names, etc.).
• Tweaked event/main_listener.php for compatibility with later versions of phpBB 3.3.x.
• Rearranged the codebase in ways (figured out by others credited above) that resolve problems with later versions of phpBB 3.3.x (e.g. due to having files stuck in styles/all/angular/ and called with paths that have /../ in them).
• Rearranged the codebase in new ways that just make far more sense (e.g., files that are basic functionality of the extension, not specific to ProSilver, are no longer in styles/prosilver/template/ but in styles/all/template/).
• Added a sorting function to service/tags_manager.php. When called, it will sort a tag list alphabetically (per localization rules), and then secondarily apply human-friendly "natural" sorting of numeric tags. This is presently tied to global localization settings; I'm unaware of a way to do this using user-specific language preferences of different board users, because the variable holding that information is just simple language codes like en or ru that do not correspond to localization names used by PHP (e.g. en_US.UTF-8). Anyway, this sorting has presently been applied to the all-tags list provided by ACP > Extensions > RH Topic Tags > Manage Tags. Not yet applied to tags shown on topics, on posts, or on tag cloud.
• Changed language/en/topictags_acp.php to permit more characters as valid in tags, such as underscore, dot, and accented letters. Commented-out code blocks in there (with notes) also add support for Greek, Cyrillic & Hebrew, or for permitting letters/idiograms in any language at all, or even for dumbing it back down to forbid diacritics. Also permits tags of min. 2 characters by default, to account for common acronyms like "AI" and "UK".
• That upgrade has also been done in the interface files for French, Russian, and Spanish (the other languages supported by this extension so far). The Russian implementation defaults to the regex that permits Cyrillic letters, for obvious reasons. All the rest default to Western European (including Latin-alphabet letters with diacritics since they are common, and even used in English, e.g.: Brontë, financée, façade, jalapeño).
• Edited language/en/topictags.php and language/en/topictags_acp.php to make much more sense; there were various grammar and typographical glitches, as well as some unclear wording generally. Only some of these improvements have been propagated to the other-language versions, since some of it needs native-level fluency in those languages. One particular issue in them that's been fixed was rampant abuse of SCREAMING ALL-CAPS as a form of emphasis instead of using the standard HTML em and strong elements for semantic emphasis.
• The typography in the French and Russian versions has been improved with regard to guillements instead of English- and Spanish-style quotation marks, and other punctuation tweaks, as well as indication of Cyrillic alphabetical order in the ru version.
• Also replaced the awkward ⇒ arrow with the → one in a menu, in all languages, so it's easier to tell what the character actually is.
• Fixed missing internationalization strings for Russian and Spanish. And various previously untranslated strings have been translated, including for French (via Google Translate with some manual adjustments). Even the commented-out notes about various regex options, in the source of language/xx/topictags_acp.php files, have been translated.
• In all languages, incorrect references to minus (−) or dash (–, —) characters has been replaced with correct references to the hyphen character (-, which Unicode confusingly calls "hyphen-minus"), as the character to which spaces will (optionally) be converted in tags.
• Fixed invalid HTML in styles/all/template/tagcloud.html.
• Fixed trivial typos in styles/all/theme/rh_topictags.css and service/tags_manager.php.
• De-obfuscated the code of styles/all/ng-tags-input.min.css, since humans trying to adjust the display of their websites need to read it, and the efficiency gained by compacting this particular file is virtually non-existent. If you have a mega-busy board and need to compact all of your code, then do that will a tool for this on your production server. We don't wreck the development-side code for all humans just so one person's website runs a tiny bit faster.
• Updated/corrected composer.json for version, dev & requirements info. For some reason, RH's original master-branch version claimed it was v3.0.0 in this file (but nowhere else – it was otherwise labeled 1.0.1), while the stale development branch for phpBB 3.1.x was even more confusingly numbered 1.0.2. Subsequently, various forks have been called 1.0.1, 1.0.2, possibly 1.0.3, 3.0.0, and 3.0.1. This newest one (as of this writing) is numbered 3.0.2, since it supersedes all of those.
• Added migrations/release_1_0_3.php, and migrations/release_3_0_0.php through migrations/release_3_0_2.php files that should account for any other variants people have installed. Not sure what purpose these things serve, but them being missing would presumably be problematic somehow.
• Fixed misspelling of lead dev's name as "Robet" at every place that occurred.
• Fixed copyright notices in file headers to use actual copyright symbol ©, instead of "(c)" which is actually (and always has been) legally meaningless nonsense. A valid copyright notice is of the form "Copyright YYYY CopyrightHolderName" or "© YYYY CopyrightHolderName" (while "Copyright © YYYY CopyrightHolderName" is redundant but not actually invalid). A string of "(c) YYYY CopyrightHolderName" is useless gibberish. Why anyone would try to use "(c)" I don't know; this is 2024 not 1984 and Unicode exists for a reason. This is GPL anyway, so it doesn't really matter much, but I'm a stickler for such things.

Known issues

• Someone on the phpBB forum reported that one or more earlier attempts at updating this extension (attempts on which the present code is partially based) did not work in phpBB 3.3.14 (currrent version as of 2024-12), but they did not provide any debugging information at all, so it's just unknown what the issue might be, or whether it's even an actual issue rather than someone's misconfiguration. No attempts to get this to work under 3.3.13 have been reported yet, only 3.3.5 through 3.3.12.
• The tags created with this extension are not searchable by the built-in search function of phpBB or any known search extension. To search for uses of a tag, you have to go to https://yoursite.com/tag/tagname where tagname is the name of the tag in question, and as noted near the top of this page there are some simplistic search parameters. There is also no wildcard version of this, just a tag cloud. This means the tagging functionality is of sharply limited utility (especially if you have turned off the tag-cloud feature), so this is something to look into improving.
• The privacy/security problem of the tag cloud formerly being visible to the world instead of only to logged-in visitors has been hit with a blunt instrument. If there are use-cases for this information being totally public, then it can probably be re-implemented as a settings option instead of just the visibility being hard-coded as denied to anyone not logged in. Or you can make that happen yourself by removing and S_USER_LOGGED_IN from the opening IF statements in styles/all/template/tagcloud.html and styles/all/template/event/index_body_block_stats_append.html if you like, without waiting for any further development. Just purge the cache afterward.
• There's still a less serious privacy/security problem with the tag cloud: Tags that are used (presently) only in a forum to which the logged-in user does not have access will still be shown in the tag cloud. The usage count for a tag in the cloud (if the count feature is on) will include instances in forums to which that user does not have access. The first of exposes internal-only tags to those who should not know them, and the second reveals to the user that there is hidden content they don't have access to. In both cases, clicking on such a tag will not show posts, titles of posts, or even forum names that the user can't access, so it's not as bad as it could be. See adm/style/manage_tags.js, which has various checks in it, for possibly how to approach this (though I do not know why this core functionality file is in a style/ directory, since it appears to have nothing to do with themes and other presentation).
• Going to https://yoursite.com/tags/ does not work, only https://yoursite.com/tags with no trailing slash, but these URLs canonically should be treated as equivalent. There is a https://yoursite.com/tags/suggest page (loading a script that takes data from another, and is used by various functions), so https://yoursite.com/tags/ does actually exist.
• The tags shown on a post are alphabetized in "computerese" style, with "A", "B", "C", etc. grouped before "a", "b", "c", etc. This is undesirable as it is confusing for human users. I may be looking for loadTags function.
• See add-on-comma="false" in adm/style/topictags_blacklist.html, adm/style/topictags_whitelist.html, styles/all/template/event/posting_editor_subject_after.html, ``, possibly in other places. May be possible to turn on ability of comma to serve same as Enter/Return in ending a tag, which is common/expected behavior, and makes sense since commas cannot be used in tags anyway.
• There appears to be a significant amount of code in here (e.g. in service/tags_manager.php) to support an option for case-sensitive tagging (or at least case-sensitive sorting and other display considerations regarding tagging; the full intent isn't clear yet). But there is no ACP option to enable such a thing, it's always defaulting to "false" or even hard-coded that way in a few places (i.e. to be case-insensitive).
• Case-sensitivity of actual tags would probably be undesirable for most use-cases (e.g. if someone creates a "YouTube" tag and someone else writes it as "Youtube" or "youtube" or "YOUTUBE" you end up with redundant tags, and this is especially likely on a busy board with many topics and users). But a niche recipe site with tagging controlled by only a few editors, for example, might want to distinguish between Turkey the country and turkey the bird or between Chile the country and chile the pepper.
• Case-sensitivity of display of tags in a list, however, is good. Something best done (to the extent feasible) in compliance with localization (different languages alphabetize differently, especially with regard to characters with diacritics). The original behavior seems to have been to do no sorting in some places (accept database-entered tag order), and to sort in "computer-friendly" manner in others (A, B, C, etc. grouped before a, b, c, etc., and human-unfriendly number handling that treats 02 as less than 1. This "user-hateful" style has been fixed at ACP > Extensions > RH Topic Tags > Manage Tags (list of all tags), but not yet elsewhere, such as in the tags listed at a topic, or in tag cloud).
• Tag cloud in particular is sorting things in order of most to least frequently used, which makes the sizing stuff it is doing redundant. Tag clouds are typically alpha order with the size indicating frequency.
• Making any/all of this work might be very easy or might be a massive endeavor, depending on the development and testing state of the code relating to this, which is still under some investigation. Part of it may involve changing @casesensitive into a class property addressed as @this->casesensitive.
• In service/tags_manager.php there is a "Note: that $query needs to be at least 3 characters long", and code like if (utf8_strlen($query) < 3); this may have to be changed to support 2- and 1-character tags. Depends on exactly what circumstances this 3-char. constraint is being applied to. So far, it looks like this only affects get_tag_suggestions(), but it's not clear that this function actually aligns well with its name (i.e. it may not be limited to the tag-suggestion feature of trying to match existing tags when you enter a few characters).