Systems Craft

Decision Lab

Small production-minded demos for the choices that shape reliable data and machine learning systems: latency budgets plus statistical modeling workflows where syntax, diagrams, and diagnostics need to agree.

Hot-path accounting1/2

Latency Budget Simulator

Allocate a request budget across feature fetch, scoring, policy checks, and response shaping to see where tail latency quietly steals reliability.

LatencyC++p99Profiling

p95 request path

163ms total against a 180ms budget

17ms spare

Feature fetch58ms

Remote joins dominate p95.

Model score46ms

Batching is underused.

Policy checks35ms

Rules are serialized.

Response24ms

Payload shaping is stable.

Read low-latency notes

Model syntax2/2

lavaan SEM Workbench

Translate lavaan syntax into a path diagram, then inspect how measurement loadings, structural paths, and fit diagnostics support an SEM workflow.

SEMlavaanRFit indices

PoliticalDemocracy SEM

Build `ind60`, `dem60`, and `dem65` from indicators before reading the structural paths.

=~latent measurement

~structural path

~~residual covariance

Open SEM lab