context in template shows no value

Defined a context in the configmap and the notification was trigger. However the .context.fieldname always shows this is with Argo rollouts. Here is the configmap for the notification
...
data:
context: |
region: "east"
environmentName: "staging"

service.webhook.form: |
url: http://172.20.2.210:4566/00000000000/canary-status-queue
headers:
- name: Content-Type
value: application/x-www-form-urlencoded

template.rollout-completed: |
webhook:
form:
method: POST
body: Action=SendMessage&MessageBody={"environment":"{{ .context.environmentName }}","rollout":"{{.rollout.metadata.name}}","status":"completed"}

{{.context.xxx}} are in several sample templates, does this field only work for ArgoCD?

Start with the notification ConfigMap's context and template.rollout-completed entries, then trace how context values reach template rendering for Argo Rollouts. Compare the sample templates using .context with this configuration and verify whether environmentName renders as staging; done means the configured context value appears in the webhook body or the limitation is documented.

Written by the indexing model from the issue text.