{{ env }} not usable

I'm not sure if it's me doing stupid things or not undertanding how this all works, but...

Looking at the actions documentation, it looks like I should be able to use {{ env }} in my jinja expression, but this is actually failing:

---
description: T
enabled: true
entry_point: 't.sh'
name: t
runner_type: local-shell-script
parameters:
    t:
        type: "string"
        description: "T"
        required: true
        default: "action: {{ action_context }} execid: {{ env }}"
        position: 1
...

The t.sh script just echoes its given parameters

Results in this:

  stdout: '{u''trace_context'': {}, u''user'': u''stanley'', u''pack'': u''oiobuild''}'

What I want to do is use execution ID in a "notify" to let user have a back link to st2:

notify:
  on-success:
    message: "To find more details, go to: https://stackstorm.openio.io/#/history/{{ env.ST2_ACTION_EXECUTION_ID }}/general"

I didn't find any help in the doc, even if the env() one, from here looked promising...

What am I missing ?

Start with the built-in parameters section of the actions documentation and the action YAML example, then compare it with the Mistral Jinja env() documentation. Reproduce the default parameter and notify expressions using the shown local-shell-script action. Done means the supported syntax and the observed execution-ID behavior are reconciled in the implementation or documentation.