**Updated Original PR Description**
## Summary
This PR adds a small, controlled set of scheduling fields to WorkerPool
so WorkerPool-managed Pods can be placed onto appropriate Kubernetes
nodes.
Added fields:
- `nodeSelector`
- `tolerations`
- `priorityClassName`
- `nodeAffinity`
## Scope
This intentionally does not expose a full `PodTemplateSpec`, and does
not add support for full `affinity`, `podAffinity`, or
`podAntiAffinity`.
Resource requests/limits are intentionally left out of scope for this CL
while the WorkerPool resource model is still being discussed separately.
The goal is to keep the first version small while addressing the
WorkerPool-to-Kubernetes-Node scheduling gap discussed in
[#212](https://github.com/agent-substrate/substrate/issues/212).
`nodeAffinity` is included to support heterogeneous node pools where
`nodeSelector` is too limited, such as requiring or preferring one of
several equivalent accelerator/local-SSD/cache node pools, or expressing
soft preferences during node pool migration.
`priorityClassName` is included to help preserve warm WorkerPool
capacity under cluster pressure. Since WorkerPool pods are the slots
available for actor resume, higher-priority pools can protect
latency-sensitive or interactive actor workloads from displacement by
lower-priority batch workloads, and allow different WorkerPools to
represent different service classes, e.g. interactive vs. batch.
## Related issue
Part of #212.
Related to #47.
## Problem
`go test -v ./...` (the `run-tests` job) intermittently fails during
envtest **setup** — not in any test logic:
- `fork/exec .../kubebuilder-envtest/k8s/1.36.0-linux-amd64/etcd: text
file busy`
- `setup-envtest: ... unable to create file kubectl from archive for
version-platform pair 1.36.0-linux-amd64`
Three packages use envtest (`cmd/ateapi/internal/controlapi`,
`cmd/atecontroller/internal/controllers`, `pkg/api/v1alpha1`). `go test
./...` runs them as separate test binaries **in parallel**, and each
`TestMain` shells out to `setup-envtest use`. On a cold cache they race
to download, extract, and exec the **shared** kubebuilder binaries —
hence `text file busy` (exec'ing etcd while it's still being written)
and the archive-extraction error.
Seen on `main` (e.g. the #259 push run) and on PRs. It only reproduces
on a **cold** cache, which is why it's intermittent and doesn't show up
locally once the cache is warm.
## Fix
Add `internal/envtestbins.BinaryAssetsDir()`, which runs `setup-envtest
use` under a **cross-process file lock** (`flock` on a fixed file under
`os.TempDir()`, shared by the sibling test binaries). The first caller
populates the shared cache while the others wait, then they hit a warm
no-op path lookup. The duplicated setup in all three `TestMain`s now
calls this helper.
The lock scope (user/machine-global) matches the resource it guards —
the kubebuilder binary cache is itself user-global, shared even across
repo checkouts.
## Testing
Reproduced locally by moving the warm cache aside and running the three
packages concurrently: it fails without the lock and passes with it.
Full `go test ./...` green.
Test-only change; no production code touched.
han2ni3bal-pixel