I think there might be a Lua script??
We don’t need it, I have better.
Diffuse and sharpen module. Using second order partial derivative equations of anisotropic heat transfer in wavelets space. Also works for dehazing or increasing local contrast. Has 2 different ways of avoiding edges to prevent halos.
It’s kind of slow, though.
The same algo can do:
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surface blur (just with different parameters):
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Blooming:
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Dehazing
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Inpainting (although just on small parts and I don’t reproduce the results of the litterature).
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Certainly looks capable of some heavy lifting. Love that bloom too.
More subtle sharpening (similar to the RT results in the first post) is also possible! IMO @anon41087856’s is a little overdone.
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One thing to take into account is I used the OP XMP, which overdoes the black thresholding. It still looks good zoomed at full-picture level, and I would advise against pixel peeping to setup this kind of algo (unless you need to assess the technical perf of the algo – but that’s not retouching anymore), since nobody goes into museums with a magnifying glass to count the number of threads of the canvas…
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Another version using diffuse/sharpen but also using the details masking (which is available in darktable 3.6) to exclude the sky. Still not perfect for the pixel-peepers but I’m still getting my head around this module:
Either way, this module is magic, especially now it has OpenCL support.
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Agreed
The dark horizontal line between sunlight and shadow towards the bottom of the image is easy to catch without pixel peeping, though without having used the module, I’d assume that can be avoided. Most instagrammers probably wouldn’t notice it, but this is pixls 
@hannoschwalm Capture sharpening works so well and others concur. Would it not be a good time to port it over to darktable?
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Why? It was said and demonstrated that Diffuse & Sharpen work equally well.
Maybe I missed that. Can you please show me where that was demonstrated.
Message above, from June 2021, post by anon41087856.
Let’s not resurrect this old thread when we had recent discussion on the topic. See here: Settings for fine details (compared to other tools).
In particular, check out the comparison here: Settings for fine details (compared to other tools) - #108 by qmpel.
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I don’t think thats an appropriate match by any means. Not sure what AP did there, that looks pretty ugly.
I think the thread didn’t deliver so far. So, I will give it a shot with the current DT version. I throw in this 100% crop, which looks pretty similar in sharpness, compared to the OP. At least in my opinion.
DSC00662.ARW.xmp (11.6 KB)
Happy to see if someone produces a better match. We can all learn together.
The sharpening in the OP seems to be a bit overdone, I can see tiny rectangles, maybe sensor artefacts (?), I think. These are also visible in DT, and in my version too. Just something I observed.
what‘s the value of sharpness in this sample? That sample doesn’t contain meaningful details that benefit from sharpness …
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I see this more as a technical challenge to “sharpen your knife” or to add to your toolbelt, for when its needed.
darktable isn‘t designed to win technical challenges…
it’s all about the image
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that’s just your view 
I mean, look at the play raw, lots of them carry technical challenges and all can learn, how to deal with them. And even if this very picture doesn’t need to be superb sharp… the process to deblur the image is still valueable.
So I don’t see any harm. If it isn’t interesting for you, why would you care?
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I am not fully convinced here. IIRC CS works in raw space so we have slightly better data already for the demosaicer. RCD at least gave some better micro-detail. BUT - the difference was pretty small for me and D&S is in really good shape (i love the presets 
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Quote from rawpedia:
It [the Capture Sharpening tool] is applied to the raw file immediately after demosaicing and modifies the data in linear gamma to limit halo generation. This means that it will only work on raw files .
And fwiw, with the other differences between the images within each example, I’m not convinced (about either being better than the other).