Kostyantynivka direction. The fog mostly cleared up, and as "promised", here is the bad news.
In red I marked Russia's main attack routes.

Illinivka: Russian forces advance from Oleksandro-Kalynove to the former blockpost, to the forest south of Illinivka, and then cross the Dovha stream to reach northwestern Illinivka, where they're detected and struck.
In the Illinivka sector, we can also find one of the biggest problems of the whole direction that arose during foggy periods: Russian infiltrators entered the Ukrainskiy Khutir district of Kostyantynivka, and some of them are still alive.

Berestok: Russian infantry literally floods the area around the reservoir from 3 sides, even crossing it while frozen, with the aim to reach and accumulate south of Berestok.
Lately, we have seen many such attacks in this same direction, which makes me think that a critical mass is about to be reached here, south of Berestok, and that the Russians might attack Kostyantynivka's southernmost outskirts soon.

Ivanopillya: Russian forces continue attacking, passing through Nelipivka and Ivanopillya and trying to reach Santurynivka, generally without success.

Kostyantynivka: Russian forces attack Santurynivka directly from the southeast from dachas "Yahidka", without success.
In the eastern part of the city, problems are arising in the Hora district, which has been reached multiple times (also shown by public geolocations) by Russian forces. To do this, they go from Stupochky to the big forest east of the city to dachas "Metalurh", then to dachas "Khimik", and then finally into Hora.

Chasiv Yar: Russian forces attacked the southernmost part of the town, with limited success.
More importantly, a group of Russians reached southeastern Chervone, with some of them still being alive.

Notable Ukrainian engineering structures built in the period 01/02 - 04/02.

1. +140m of barbed wire northeast of Vozdvyzhivka, Zaporizhzhia Oblast', Ternuvate direction (47.776165, 36.118712). The building direction is east. This denies claims of Russian control over the railway line and much of the fields west of Dobropillia.

2. +130m of barbed wire west of Tykhe, Dnipropetrovsk Oblast', Pokrovske direction (47.970189, 36.350504). The building direction is southwest. This denies claims of Russian control over Tykhe.

3. +610m of barbed wire north of Prymorske, Zaporizhzhia Oblast', Stepnohirsk direction (47.665276, 35.291193). The building direction is southwest.
This denies claims of Russian control over northern Prymorske.

Effects of shelling in the Stepnohirsk - Kamyanske general areas