Walkers not making full loops depending on position in block.

[arctic glade]

Hey y'all, sorry to bother you with another question. I'm on Augustus 4.0 playing Campaign Reconquered, and I noticed since beginning the campaign that a lot of times after I lay out my blocks and start adding buildings to them the walker range will change from what was originally shown for an empty block. (I generally lay out the block and test the range with schools and markets.) The Reconquered Campaign is the only thing I've played since starting on Augustus 4.0, so I'm not sure if it's an issue with all of the campaign maps or Augustus 4.0.
Here's some pictures as an example. When I plotted the block out, all building walkers made a complete loop. Once some housing filled up and I began adding other services this was no longer the case.
In the first image, the school covers the entire block as planned. However, the locations I'd prefer to place it, in images 2 and 3, don't for some reason. I'd rather add service buildings to the top of the block rather than shoehorning in housing in the less desirable section, and I'm frequently flummoxed by these changes, which seem quite random to me.
The final two images are just more examples of how different the walker coverage can be based on varied locations in the same block. In the fourth shot, only one square is not covered, rather than half the length of the block, and then if I move it one tile over it magically covers the entire block again. This has caused much consternation in past levels, especially when market ladies suddenly stop covering an entire block upon the addition of further buildings and a chunk of my insulae devolve into unhappy tents, and it really seems to defeat the purpose of the walker distance preview if it's able to change with no notice.
Can anyone explain to me what's going on and how to prevent it in the future?
I can include the save I'm currently working with if that would be helpful, but I've noticed the same pattern in most if not all of the previous maps as well.
Thanks!

[vagrant quarry]

So... TLDR... likely not a bug, but feel free to post the save and I can look at it. In all likelihood, this is walker black magic (TM).

So what is happening is how walkers calculate the path. There are three phases: 1) Target 2) Pseudorandom 3) Return Destination. Schools suck because they don't have a third phase, the children puff into nonexistence (technically die) at the end of their first two phases. The target phase is the problem on these images. When the walker first spawns, it will walk towards 1 of 4 tiles. Those tiles are always 8 tiles distant from the northernmost corner. If that tile is not on a road, it walks to the nearest road tile to the target. For most buildings, the walker will go about 25 road tiles at most towards the target, then go random (if it doesn't reach it by 25 tiles, the walker goes random and if it reaches before 25 tiles it goes random at that point). The random part on a loop is just keep walking forward. Once another 25 tiles are traversed they turn into a destination walker and go home, going over gardens and roadblocks to get there (or die in the case of school children).

For the loop that completes, its targets are all on the network, no problem. For the ones that don't, they have targets to the East or West that can't be reached (other road networks) and so they just all go in one direction and don't loop.

Solution is check road networks like you are before placing housing, but also be aware that schools hate life and want to break whenever roads are placed outside the block within 8 tiles. Doesn't always matter, since sometimes they will still have one go each way on a loop and complete, but it can be janky.

Another solution that can help is placing the school inside of the loop rather than the outside... What this does is make it less likely an external road network can accidently become a target tile.

As for why it is more common on reconquered, it is because the terrain is more varied and you are having to build blocks that are not cookie cutter... Basically it brings you up against edge cases much more often.

So second TLDR: walker black magic is black magic, pre-place schools when designing, try to keep them in spots that are less likely to break (you don't expect to make road networks nearby outside the loop).

[arctic glade]

Maybe I shouldn't have used schools as an example. Other buildings such as libraries, market places, taverns, baths, and temples are doing the exact same thing on this block, but not forums or theaters, and it's a common occurrence in any map since I began the Reconquered Campaign in Augustus 4.0, not just on this single block.
As I mentioned above, I do test blocks before beginning building with schools and markets to make sure that they will make the loop (in any position I'm likely to want to place them in) and the walker paths change after I add further buildings to the block, but road tiles and gardens next to roads are unchanged. You may want to go back and scan the original post before spending time testing, as I am familiar with the walker mechs in vanilla, Julius, and earlier versions of Augustus and don't remember encountering this before, and I don't want you to waste your time testing without being familiar with the problem. Sorry it's so long-winded, I just wanted to cover everything so as not to waste people's time thinking it's a common walker issue or lack of understanding of the walker system.

[vagrant quarry]

This is what I mean by seeing the other road network. If I nuke the roads to the North of the school, the loop sorta works (still short, but that is the joys of schools). The reason that some buildings still complete besides cursed schools is that they have a longer walk path. Theater and forum both walk for a further distance. These are the ticks for different walkers (15 ticks/tile... sorta there is some other stuff going on but for this issue you can ignore it).

So theater gets to its target, but will walk 1/3 further to get there. Then, once there, will walk another 1/3 further on the other two phases.

Can you show an instance where adding/subtracting a building changes the behavior otherwise? I have tried a few locations but can't replicate on this end.

Also... wow. Just looked at your northern fortifications... I think you REALLY don't want Boudica to come visiting...

Here is another example with that same location... I changed the road for a highway here, and since highways are viewed as gardens/roadblocks I guess they don't count as valid targets. Loop improves.

and now it completes... sorta. At least covers the current housing. I only replaced roads with highways for this also, no moved buildings. If you have an example where adding/subtracting a building changes pathing post an example... as far as I am aware as long as the building does not alter the road network, the pathing should not change. If adding/removing a building is changing the pathing of other buildigns, then yeah, this sounds like a bug.

[arctic glade]

Ok, I'm a moron. I went back to the save where I'd just begun building this block and realized that I had popped the road out two tiles at some point to give myself more room, thus making the block a tiny bit longer and negating the testing I'd done at the beginning when laying it out. 🤦 Sorry for wasting your time on this.

I went back through my previous map saves to try to remember an instance where I'd had a similar problem with the walker previews not syncing up with the end result once the block was built. The couple of blocks I found had a similar issue as the one you pointed out above - there was a secondary road not touching it, but a couple tiles away, and removing that road made the walker path longer. I didn't realize that having a road separated from a building by one tile (and blocked by a building/decoration, not linked by a garden) could effect the walker path on the other road/loop. Strange, but definitely good to know and something I'll keep an eye out for the future. Thanks so much for mentioning that!

In a related but slightly opposite case, I remembered struggling to lay out blocks with the walker previews at the beginning of a few levels. For some reason with no one in the block the walker previews were much shorter than what they usually were, and once the block was populated they reverted to a proper loop, which made planning out blocks a bit more difficult. I suppose I associated it with adding housing and buildings, but in the little experiment I just did, no additional buildings were added, and the only difference was that the housing that was already laid out was then settled. (See screenshots.)

Is this an intentional mechanic, or unintended? Is there a setting to change that would go ahead and show the normal walker path before getting settlers in the block?

[vagrant quarry]

Known problem. There isn't (as I understand it) much of a solution, since the game needs to go through a "day" so that all of the daily ticks (checks) can resolve... It happens whenever you reload a save, not due to housing presence. Just give it a moment unpaused and it should resolve itself. You'll notice between those two screenshots it hasn't actually figured out where the return tile is (red tile).

And no worries on the mistake, I was once convinced that on a map sea trade was broken... Then after posting save was told I had mothballed the dock... We have all made mistakes, most of us worse than yours