I'm a bit weary of anything that comes out of AI.
Could you give a bit more background information as to how you came up with these outlines? In other words: Are these the result of conscious deliberation or is that a product of AI?

### Architecture Principles

**RT thread (250µs capable):** Only evaluates pre-computed polynomials. No planning, no Ruckig, no kinematics. Just `position = evaluate_polynomial(t)` and send to drives.

**Userspace:** All heavy computation. Ruckig, backward velocity pass, kinematics, blending. Not tied to servo cycle.

**Predictive Handoff:** When replanning is needed (feed override, etc), userspace plans from a predicted future state, not current state. RT continues executing until the handoff time, then seamlessly transitions. This decouples userspace latency from RT determinism.

**Buffer Management:** Track buffer in TIME, not segment count. Short segments and long segments treated appropriately.

I notice that you mention the use of 'ruckig', is this a decision you made or is that something AI suggested?
According to this statement (which I have not verified )the 'ruckig' library is not free for more advanced uses. (Not that this must necessarily be a deal breaker):
forum.linuxcnc.org/38-general-linuxcnc-q...nner?start=70#320906

[edit]
there seems to be a ''community" and a "pro" version of ruckig:
docs.ruckig.com/md_pages_2__intermediate__waypoints.html

There seems to be little information about the 'pro' version:
github.com/pantor/ruckig/issues/78

Again, something is not OK if you can change values of FFx and get no change in response, so are the drives set in "velocity" or "torque" mode?

giaviv wrote:

However I’m a bit limited by the low ram (8GB), low disk space and etc.

8GB should be fine, and how low is "low disk space"? Linux starts complaining only when you get under 1GB of free space, so anything above is fine.

giaviv wrote:

I realize newer models are risky, therefore some of the models I am looking at are far from new generation CPUs (like the Ryzen5 7535U)..

7535U is not "far from new", it is new and still in production, Zen3 with 15W TDP, so it is a laptop CPU and this may be bad for latency, although not always.

giaviv wrote:

Or is CPU not the only potential issue, but also things like the motherboard etc?

CPU's are mostly fine as they can change states and do stuff, mainboards are usually the latency killers depending on quality, BIOS implementation, power saving options, etc, etc, way to many to list here, but mostly bad/weak CPU power stage set to work at the edge and throttling the CPU to save itself from going up in smoke.
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As a general rule, i would stay away from those small PC's, they are cute and stuff, but way to limited thermally, the xxxxU versions are fine, but a 13900 ... oh hell no, it will be limited thermally to something like a good 4 core CPU when under load, and they fail but being limited will prolong their life a lot so...
There were some NUC's that were OK for LinuxCNC way back.
After all this, there is no way to know for sure if any of those will be OK, short of buying and testing.

I'll try to have a look at the '9D' branch later. Thanks.

which I got not much feedback..

Just as a word of caution from my own experience:
You mustn't expect to much from a forum thread like this. Few people will even read a post that long, fewer still look at the code and hardly anybody will even try to understand it. I know of at least one long time contributor, since retired, who got quite bitter about trying to get sustained and involved feedback here. Even from the very people asking for the specific feature.