docs(benchmarks): fix README — port-forward is wm_sim's job

Earlier README told users to run a second `kubectl port-forward` and
hard-coded port 33405. Both wrong: wm_sim up calls portForwardApi() in
helm_deploy.ts:213, picks a free local port, prints `[helm] API reachable
at http://127.0.0.1:<port>`, and keeps the forward alive as a child of
the wm_sim process.

Updated workflow: read the URL out of wm_sim's output, pass it to main.ts
as --host. Kept a note about restarting the forward manually when the
kubelet drops it under heavy bench load (real failure mode we hit).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

benchmarks/README.md

@@ -86,19 +86,18 @@ workflow on top of `main.ts`. See [`sim/README.md`](sim/README.md) for:
 Quick path:
 
 ```sh
-# Provision cluster + deploy Windmill (foreground; Ctrl-C tears down):
+# Provision cluster + deploy Windmill (foreground; Ctrl-C tears down).
+# Prints `[helm] API reachable at http://127.0.0.1:<port>` — note the port.
+# Port-forward stays alive as a child of wm_sim, so keep this terminal open.
 wm_sim up \
   --topology    sim/topologies/k8s-4node.json \
   --helm        ../windmill-helm-charts/charts/windmill \
   --helm-values sim/values/smoke.yaml \
   --helm-values sim/values/local.yaml
 
-# In another shell — port-forward + run bench:
-kubectl --context wm-sim-k8s-4node port-forward --address 0.0.0.0 \
-  -n default svc/windmill-app 33405:8000 &
-
+# In another shell — fire bench against the wm_sim-managed port:
 deno run -A main.ts \
-  --host http://127.0.0.1:33405 \
+  --host http://127.0.0.1:<port> \
   --token <admin-token> \
   --workload-config workloads/io_150ms_flood.json \
   --minikube-profile wm-sim-k8s-4node \

benchmarks/sim/README.md

@@ -24,14 +24,19 @@ wm_sim up \
   --helm-values sim/values/local.yaml      # gitignored; carries the EE license
 ```
 
-Then in a second shell, port-forward the API + fire a bench:
+`wm_sim up` opens its own port-forward to `svc/windmill-app` on a free local
+port and prints the URL — look for a line like:
+
+```
+[helm] API reachable at http://127.0.0.1:38291 (port-forward svc/windmill-app)
+```
+
+The forward dies with the wm_sim process, so leave the wm_sim terminal open.
+Then in a second shell, fire a bench against that URL:
 
 ```sh
-kubectl --context wm-sim-k8s-4node port-forward --address 0.0.0.0 \
-  -n default svc/windmill-app 33405:8000 &
-
 cd benchmarks && deno run -A main.ts \
-  --host http://127.0.0.1:33405 \
+  --host http://127.0.0.1:<port from wm_sim output> \
   --token <admin-token> \
   --workload-config workloads/io_150ms_flood.json \
   --minikube-profile wm-sim-k8s-4node \
@@ -41,6 +46,14 @@ cd benchmarks && deno run -A main.ts \
 Bench runs ~3 min. Report lands at `benchmarks/reports/<timestamp>/`, with
 `dashboard.svg` as the entry point. Open it in a browser.
 
+If the port-forward dies mid-bench (kubelet sometimes drops it under heavy
+load), restart it manually in a second shell with the same port:
+
+```sh
+kubectl --context wm-sim-k8s-4node port-forward -n default \
+  svc/windmill-app <same port>:8000
+```
+
 ## Prerequisites
 
 - `nix develop` from the repo flake — provisions `minikube`, `kubectl`, `helm`,
@@ -221,9 +234,11 @@ pass regardless.
   `--minikube-profile <name>` to `main.ts` if you renamed it.
 - Default kubectl context comes from minikube. Use
   `kubectl --context wm-sim-k8s-4node …` to be explicit.
-- The port-forward dies easily under heavy bench load (kubelet drops the
-  connection). If a bench fails partway with "connection refused", restart
-  PF and re-fire.
+- `wm_sim up` runs the port-forward as a child process. Killing wm_sim
+  (Ctrl-C) kills the forward. The kubelet sometimes drops the forward under
+  heavy bench load; if a bench fails partway with "connection refused",
+  start a replacement forward manually with `kubectl port-forward` on the
+  same local port and re-fire.
 - `minikube stop` is safe — VM disks persist, etcd survives, helm releases
   + Secrets all come back when you `minikube start`. `wm_sim up` does
   `minikube delete` first, so it's destructive — only use it for clean reprovisions.