I'd recommend reading this: https://drewdevault.com/2020/07/27/Anti-AGPL-propaganda.html
AGPL is based on GPL, not LGPL, and like the GPL linking would be considered creating a derivative work which should then be made available as per the [A]GPL licence.
This won't stop me licensing my work using AGPL. If commercial interests don't want to use it then I'm fine with that¹. If they do want to use my stuff but don't want to use anything covered by AGPL then they can always contact me to try negotiate a different arrangement.
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[0] IANAL, hence “might be”. Whether loose coupling counts the same as linking is a grey area IIRC. This potential confusion is why some avoid GPL/AGPL, if only to be on the safe side from their PoV.
[1] Give the choice between “give us what we want with no come back and we'll use what we want and give nothing back” and “don't give us what we want, and we'll go away and leave you alone”, I'll take option two. I get nothing either way.²
[2] As the linked article says: “If you don’t use the AGPL[³], they’re just going to take your software and give nothing back. If you do use the AGPL, they’re just going to develop a solution in-house. There’s no outcome where Google pays you.”
[3] Here they are comparing AGPL to less restrictive licenses such as MIT.
This seems less fitting if it's true that what you're "giving" is some React bindings, and what they have to "give back" is their entire frontend application.
They could also try negotiate an alternate arrangement, some authors may be willing to do that (assuming they have relevant permission from other contributors if it isn't a solo project, of course).
The example you give seems to be the unreasonable one IMO: “our thing is bigger, so we expect to use your smaller thing how we want”.
Either way your interpretation is not our intention so I'll make sure that's clarified.
The license [1] says this in section 5:
> 5. Conveying Modified Source Versions.
> You may convey a work based on the Program, or the modifications to produce it from the Program, in the form of source code under the terms of section 4, provided that you also meet all of these conditions:
> [...]
> c) You must license the entire work, as a whole, under this License to anyone who comes into possession of a copy. This License will therefore apply, along with any applicable section 7 additional terms, to the whole of the work, and all its parts, regardless of how they are packaged. This License gives no permission to license the work in any other way, but it does not invalidate such permission if you have separately received it.
If you intended it to be non-viral (weak copyleft) and based on distributing modified versions of your files, the Mozilla Public License [2] may be a better fit for the frontend libraries. Then people could use them unmodified in software with any license, but they would have to release source code of modified versions of those files. This would not do what you want for the server software though, as the "release source code" only applies when distributing software (which is not happening if it's staying on the server).
I am not an expert, and it is not clear to me whether the frontend and backend constitute a single work according to the license. This is important to investigate. If they did count as a single work, rather than two separate works communicating, then the AGPL from the server software would apply to the client software and licensing the frontend libraries MPL wouldn't work. This says something about that in the other direction: https://www.gnu.org/licenses/gpl-faq.html#AGPLv3ServerAsUser
[0] https://en.wikipedia.org/wiki/Copyleft#Strong_and_weak_copyl...
This always comes up with copyleft licenses. It's rarely 100% clear what's allowed, except maybe the LGPL where the intent of the license is obvious. Everything else is some amount of a viral license, and it's safest to just avoid it.
