Update 29 Feb 24: OIO 6.3.0 for Hotfix #20 is probably the most skippable of all the Patch 6 hotfixes but is up for completeness' sake, even though it functionally does nothing but update OIO version strings to keep me from having to answer "is something wrong?" questions about it later.  Seriously, the only thing added is some good old yet-to-be-implemented datamining bait and that's it.  That said, if you run Standard but feel like getting into the mystery of why BG3 occasionally seems to whiff on its own approval data, there's the new BG3 Bugtest version under Miscellaneous to check out.  Details can be found in the Forum thread for it.

Update 22 Feb 24: OIO 6.2.0 is here but like 6.1.0 Hotfix #19 doesn't add anything new OIO cares about besides just fixing several typos, ergo both 6.0.0 and 6.1.0 remain perfectly playable if you're not worried about a 0.00737% chance of potentially noticing stuff like somebody typed 'our' instead of 'out' or spelled his name 'Cazazdor' the one time.

Update 20 Feb 24: OIO 6.1.0 is frankly skippable if you've got 6.0.0, since Hotfix #18 didn't change anything in regards to OIO.  All that's new is just the fix to move the OIO install string to the new sample text in the options example as seen here.

Update 16 Feb 24: OIO 6.0.0 for the Patch #6 update is here, consisting of about 2100 new lines and 420 alterations (nice).  OIO has also joined Team Keep Gortash Weird and will revert the two letters he sent to their less-boring original versions (see this image and this image tooif you're confused about this).  Other than that, I have noticed a handful of loopbacks went away in the jump from 5.6.0 to 6.0.0.  I'll be looking into whether these were just due to Larian reorganizing dialog files or if they've exposed any bugs in the detection logic, so a 6.0.1 may be in the cards if I conclude it's the latter.  Also Extended people may notice Larian has rearranged where a few of the companion-specific tags get set or unset as part of the Patch 6 revamp. 

In regards to the requests for more OIO variants, OIO Personal is actually finally under development.  This will basically be a program where you download the latest definitions file off this mod page, point it at your BG3 install, set the language and what options you want or don't want, and it will automatically write up your own custom .loca in the right spot and off you go.  Theeeeoretically this means you could also patch another loca patch with OIO's additions, though that gets into some possibly weird side effects that I'm sure not going be trying very hard to run tech support on.

Update 16 Jan 24: OIO 5.6.0 to stay current with Hotfix #17 is here.  Pretty minor patch, about 10 new NOT FOUNDs covered and 40 or so typo edits.

Update 9 Jan 24: OIO 5.5.0 to stay current with Hotfix #16 is here.  Several dozen new potential NOT FOUNDs are now handled, including a couple new checks and their DC info.

Would you like to know without savescumming or consulting external wikis some things about your interaction options like:

•  Is that Persuasion check is going to need a 5 or 25?
•  Will doing this get my Paladin membership card revoked?
•  What will my squaddies will think of that?
•  Do I think this is just me being casually friendly, but they think it's an invitation into my pants?
  

Then this mod has got you covered.  OIO annotates dialog options with in-game data to let you know what is coming down the path you may (or may not, now that you've seen what's coming) take.

Your options are:

OIO Standard: Approval points, Oathbreaker warnings, roll DCs, the ←← indicator for choices that don't advance the dialog, and romance-related statuses.

OIO Standard Worldwide: It's Standard, but for all the other supported BG3 languages.  Unfortunately, due to the fact that I would like to only have to do 16 manual xml-to-loca conversions through ExportTool per update at the moment, this is the only non-English version that's likely to ever exist (until I figure out some even more radical automation solutions, anyway).  Radical automation solutions acquired (though boy howdy un-compiled 7zipping sure takes like 50 times longer).

OIO Extended: Standard + more status info related to your companions, their personal quests, and camp events.  Little bit spoilery, probably better for a second playthrough on.

OIO Extended Worldwide:  It's Extended, but for all the other supported BG3 languages.  It's up to you to decide whether all the extra English is a) vaguely imperialist or b) the more preferable alternative to being subjected to screamingly terrible MTL translation attempts.

OIO Spoileriffic: Extended, but I turned off the part of my generator that filters out all the endgame-related things.  More spoilery and not recommended unless you're on your 4th-or-more playthrough trying to arrange the mostest perfectest ending you can.

OIO DCs Only: Only want the heads up about the skill check DCs?  Well, at least two people in the comments did, so now it exists.  It also gets the loop arrows now too because all versions do, which arguably makes it kind of mislabeled going forward, but oh well.

OIO DCs Only Worldwide:  It's DCs Only, but for all the other supported BG3 languages, which makes it the least annoyingly English option.  Not that I am stating for the record that the English are annoying, because that would be quite rude.

About OIO and multiplayer:
OIO is fully compatible with multiplayer.  Only the players with OIO installed will see OIO things, so don't worry about spoiling your buddies (or them spoiling you, conversely).

About OIO and the ←← indicator:
Added to help out those of you who want to wring the most content per interaction as you possibly can, the arrows signify the informally named "loop indicator", which represents a choice that doesn't advance the dialog and brings you back to this choice at the end so you can then pick something else (kinda like the old Mass Effect left-side options).  And you'll also know that by the absence of any arrows that you only get one shot to pick here.  Sometimes this can be conditional on a roll, for example "←← on Fail", so you can also see which options may let you try something else depending on what result.

About OIO and achievements:
Achievements are not affected.  OIO is a file override, so it's not a "real" mod (as far as the achievement blocker cares, anyway).

About OIO and approvals:
Fairly self-explanatory: the option will get you the points (if the companion is present).  Names are shortened to the first three letters, but since that obviously doesn't work very well for Minsc and Minthara, they are 'Msc' and 'Mth' instead.  You may also (VERY rarely) see these others that are presumably leftovers from alpha and testing etc:

• Alf is Alfira.  Getting points with her has no particular effect other than to stoke fan theories that she was supposed to be 'the bard companion' but got cut during development.  (Judging by the number of existing but unused Alfira flags in the internal data, this is exactly what happened.)
• Dur is the Dark Urge, i.e. you (maybe).  Getting points with yourself has no particular effect other than it may or may not lead to an overinflated ego.
• Tes is the Generic Test character.  Getting points with them has no particular effect other than providing a good opportunity to reflect on their memory and the mortality we all eventually face.  Generic may not have survived to see full release, but they were a real one.
  

About OIO and oathbreaking:
Not all oathbreaky things are bad for all paladins.  Something marked DevotionBrokeOath won't get a Vengeance paladin in big trouble, for instance.  If it just says BrokeOath, though, then that IS bad for all of them.

Also bear in mind OIO can only warn you about cutscene-action types of things that directly lead to oathbreaking within the dialogue scene.  If you say you'll do Oathbreaky Thing X in the dialogue, but don't actually follow through and do it right then and there because Oathbreaky Thing X is something you have to do as a world action outside of dialogue etc., OIO won't be able to warn you about it if it doesn't get proc'd inside the dialogue. 

About OIO and DCs:
I didn't really need to add +Adv for rolls with advantage since you can see that with mouseover, but I just felt like it's a nice QOL addition.  Also, now an * by the DC number means "derived by calculation".  Nobody has been complaining about my calculations being wrong yet, so they're probably not buggy and I can get rid of the * now, but eh, just in case.  There are a small handful of known weird cases that are kinda tricky to deal with due to some degree of essential uncertainty that I haven't yet assigned a DC estimation to yet, but they're pretty hard to find.

About the use of 'or' in OIO:
Some approvals will say things like (Ast +1 or -1).  These are generally attached to a roll, so you can assume you'll get one or the other depending on the roll results.  They can also be dependent on whether you've done other story-flagged things before.  Similarly, sometimes you'll see two flags together like (made-up example) [KarlachConvinced][KarlachWasntConvinced].  This doesn't mean both are being set, it's generally one or the other depending on a roll result or, again, other existing story-flagged things.  The development of the displayed on Pass/on Fail branching logic has cleared out most of the 'or' results, but there are still a few that depend on existing story-flagged things.


Installation:
There's a visual guide to this over in the images, btw.
Trying to do this as a mod seems a little wonky at present due to [insert technical reasons here], so rather than overcomplicate everything this is just going to be a dumb straight up file override.  If you're on Vortex, it should identify the mod as a replacer, so let it do its thing with that.  For manual installs, the download will be a compressed Data / Localization / English folder structure with an english.loca file inside.  Unzip and copy this into your Baldur's Gate 3 directory (there should already be a Data directory there to merge with, here's how to find it on Steam) so it creates any directories as needed.  To uninstall, just delete the english.loca.  This file won't affect any saves either by adding or deleting (when it's gone, BG3 reverts back to using the version contained in the game's .pak files like it did before.)

Do note that because this is not a mod that tries to merge a list of only the changes but is a file override, it is only compatible with the patch version it was created from.  At the time of this writing, that is Patch 3 Hotfix 1.  Subsequent patches and hotfixes can (and let's be real, will) add changes that this mod will then rollback, so when patch day rolls around you should delete that english.loca file and wait for a new one (or just, you know, go back to playing BG3 without helpful predictive insights for a while).  They aren't very time-consuming to generate, so I don't anticipate it will take too long to catch up with Larian when new patches or hotfixes drop (and if I ever get tired of the fairly minimal effort of maintaining it anyway, I'll just post the generator code on github and somebody else can take over doing this, I guess).

Checking that OIO is working:
It's simple to check and you don't even need to load a save first.  From the main menu, pick the options, the interface tab, then adjust the dialogue display settings.  In the test window, you'll see an OIO message with the version and number if it's been successfully installed. There's a visual guide to this in the images, too.

Known incompatibilities:

• Default language replacers: if you have a mod that for example turns the English into Korean, OIO will turn it back into English because they're trying to overwrite the same thing, and only one of them can do it.
• Font replacers (potentially): if you have a mod that changes the dialogue font, the ← might turn into a � or something if that font doesn't have a glyph for the arrow.  (Though you can use the de-arrowing guide to change the arrows to '(loop)' or something that does show up instead of deleting them, if you want.  But don't use < or > because you'll probably break the XML file.)
• Mods that do the same thing OIO does:  I mean, this one should be pretty obvious, but there you go to make it all official and such.
• Symlink utilities:  The way OIO is intended to work is that BG3 loads the OIO override .loca when it's placed in the right folder instead of using the one zipped up in the default English.pak (or whatever language.pak) file.  Symlinking screws up BG3's ability to find the default English.pak files, so it can only find the OIO .loca and nothing else.  Those other files contain the parameters for how to play the accompanying audio files among other things, and so voices stop working.  Strictly speaking you shouldn't be using symlinking with OIO anyway, since fundamentally symlinking is for managing replacement files, not override files.
  

The future of OIO, with variable degrees of certainty:
There are a number of story flags that basically serve no purpose but spam: things that I've filtered out like [YoureTalkingToLaezelNow True] (the real names aren't quite that literal, but still) which are necessary for game logic but obvious and irrelevant to players.  But BG3 is big and I severely doubt I have caught ALL of them.  So I'll be checking posts every so often to see if there are any more annoyingly recurring ones to add to the go-away list.

Also while I've hammered out all the weirdness in my dialog code parser I could find, there could very well be (probably are) some edge cases I haven't yet noticed.  So if any misses are found that-a-way and reported, they will be addressed.

Also I may look into seeing if I can work out some explanations for 'or' results, but I'm wary about making all the options too spammy and I'm not 100% sure it would be worth the effort.  Hey, this worked.

Also this mod is remaining English only for now, mainly for two reasons:  Disregard that, significant portions of the globe now are no longer safe from OIO Worldwide.

Having scribbled out the above two I suppose the next frontier for OIO is seeing if this can be done via scripting instead, which would enable creating just one single version that works with all languages, even default replacers, and lets you turn on or turn off whatever bits and bobs you want.  It may or may not be possible to do this without grinding BG3 down to a stuttering 3 FPS slideshow depending on certain stuff, but that's the fun of experimentation.

And that's OIO. Have fun, Tav!