Python

Python fills the backend role, and it is the stack with the most to prove automatically — a suite that runs, and a service that starts and answers.

What names route here#

Django, Flask, FastAPI or plain Python all route to the Python backend starter. The starter is installed as an editable package with its development extras, so the test suite is runnable from the moment it exists.

What the gate checks#

Static probes
The source parses and its wiring is present, before anything heavier runs.
Tests
The suite runs, and a failure is re-run once from a fresh process — only a reproducing failure counts.
Start and health
The service is started on a loopback port and its health route polled.
Scope
A file outside the task’s declared paths fails before the tree is even compiled.

It pairs with a front end cleanly

Naming a Python backend and a web framework in one request produces a two-service plan in disjoint directories, so concurrent tasks cannot collide.

StacksNode.jsNode fills the backend role. It gets the full verification path, including being started and asked whether it is alive.StacksNext.jsNext.js serves its own API, so naming it answers the "do we need a separate backend?" question — and it gets the full verification treatment, up to and including being started.FeaturesVerificationEvery gate used to reason about the tree without ever starting it. Now the tree has to compile, the suite has to run, and the application has to boot and answer before anything is called finished.