docs: general fixes and improvements (#13417)

www/apps/book/app/learn/fundamentals/workflows/conditions/page.mdx

@@ -8,11 +8,11 @@ In this chapter, you'll learn how to execute an action based on a condition in a
 
 ## Why If-Conditions Aren't Allowed in Workflows?
 
-Medusa creates an internal representation of the workflow definition you pass to `createWorkflow` to track and store its steps. At that point, variables in the workflow don't have any values. They only do when you execute the workflow.
+Medusa creates an internal representation of the workflow definition you pass to `createWorkflow` to track and store the workflow's steps. At that point, variables in the workflow don't have any values. They only do when you execute the workflow.
 
 So, you can't use an if-condition that checks a variable's value, as the condition will be evaluated when Medusa creates the internal representation of the workflow, rather than during execution.
 
-Instead, use when-then from the Workflows SDK. It allows you to perform steps in a workflow only if a condition that you specify is satisfied.
+Instead, use `when-then` from the Workflows SDK. It allows you to perform steps in a workflow only if a condition that you specify is satisfied.
 
 <Note title="Tip">
 
@@ -72,22 +72,29 @@ In this code snippet, you execute the `isActiveStep` only if the `input.is_activ
 
 ### When Parameters
 
-`when` accepts the following parameters:
+`when` accepts two parameters:
 
 1. The first parameter is either an object or the workflow's input. This data is passed as a parameter to the function in `when`'s second parameter.
 2. The second parameter is a function that returns a boolean indicating whether to execute the action in `then`.
+    - You can perform conditional checks or use conditional operators in this function, but only on the function's parameters.
 
-### Then Parameters
+### Then Callback Function
 
-To specify the action to perform if the condition is satisfied, chain a `then` function to `when` and pass it a callback function.
+To specify the action to perform if the condition is satisfied, chain a `then` function to `when` and pass it a callback function. The callback function is only executed if `when`'s second parameter function returns a `true` value.
 
-The callback function is only executed if `when`'s second parameter function returns a `true` value.
+The callback function passed to `then` is treated the same as the workflow's definition function. That means:
+
+- You can execute steps in the callback function.
+- You can't [transform data and variables](../variable-manipulation/page.mdx) in the callback function. Instead, use `transform`.
+- You can't use if-else conditions in the callback function.
+- You can't use loops in the callback function.
+- You should keep in mind the [workflow constructor constraints](../constructor-constraints/page.mdx) in the callback function.
 
 ---
 
 ## Implementing If-Else with When-Then
 
-when-then doesn't support if-else conditions. Instead, use two `when-then` conditions in your workflow.
+`when-then` doesn't support if-else conditions. Instead, use two `when-then` conditions in your workflow.
 
 For example:
 
@@ -166,9 +173,15 @@ const { isActive } = when(
 ).then(() => {
   const isActive = isActiveStep()
 
-  return {
+  const returnData = transform({
     isActive,
-  }
+  }, (data) => {
+    return {
+      message: data.isActive ? "Active" : "Not Active",
+    }
+  })
+
+  return returnData
 })
 ```