docs: document when-then name

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

@@ -8,19 +8,17 @@ 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 its 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.
+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 satisified.
 
 ---
 
-## What is the When-Then Utility?
+## How to use When-Then?
 
-when-then from the Workflows SDK executes an action if a condition is satisfied. The `when` function accepts as a parameter a function that returns a boolean value, and the `then` function is chained to `when`. `then` accepts as a parameter a function that's executed if `when`'s parameter function returns a `true` value.
+The Workflows SDK provides a `when` function that is used to check whether a condition is true. You chain a `then` function to `when` that specifies the steps to execute if the condition in `when` is satisfied.
 
 For example:
 
@@ -77,4 +75,101 @@ In this code snippet, you execute the `isActiveStep` only if the `input.is_activ
 
 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.
+
+---
+
+## Implementing If-Else with When-Then
+
+when-then doesn't support if-else conditions. Instead, use two `when-then` conditions in your workflow.
+
+For example:
+
+export const ifElseHighlights = [
+  ["7", "when", "This when-then block acts as an if condition."],
+  ["16", "when", "This when-then block acts as an else condiiton."]
+]
+
+```ts highlights={ifElseHighlights}
+const workflow = createWorkflow(
+  "workflow", 
+  function (input: {
+    is_active: boolean
+  }) {
+
+    const isActiveResult = when(
+      input, 
+      (input) => {
+        return input.is_active
+      }
+    ).then(() => {
+      return isActiveStep()
+    })
+
+    const notIsActiveResult = when(
+      input,
+      (input) => {
+        return input.is_active
+      }
+    ).then(() => {
+      return notIsActiveStep()
+    })
+
+    // ...
+  }
+)
+```
+
+In the above workflow, you use two `when-then` blocks. The first one performs a step if `input.is_active` is `true`, and the second performs a step if `input.is_active` is `false`, acting as an else condition.
+
+---
+
+## Specify Name for When-Then
+
+Internally, `when-then` blocks have a unique name similar to a step. When you return a step's result in a `when-then` block, the block's name is derived from the step's name. For example:
+
+```ts
+const isActiveResult = when(
+  input, 
+  (input) => {
+    return input.is_active
+  }
+).then(() => {
+  return isActiveStep()
+})
+```
+
+This `when-then` block's internal name will be `when-then-is-active`, where `is-active` is the step's name.
+
+However, if you need to return in your `when-then` block something other than a step's result, you need to specify a unique step name for that block. Otherwise, Medusa will generate a random name for it which can cause unexpected errors in production.
+
+You pass a name for `when-then` as a first parameter of `when`, whose signature can accept three parameters in this case. For example:
+
+export const nameHighlights = [
+  ["2", `"check-is-active"`, "The when-then block's name."],
+  ["10", "return", "`then` returns a value other than the step's result."]
+]
+
+```ts highlights={nameHighlights}
+const { isActive } = when(
+  "check-is-active",
+  input, 
+  (input) => {
+    return input.is_active
+  }
+).then(() => {
+  const isActive = isActiveStep()
+
+  return {
+    isActive
+  }
+})
+```
+
+Since `then` returns a value different than the step's result, you pass to the `when` function the following parameters:
+
+1. A unique name to be assigned to the `when-then` block.
+2. Either an object or the workflow's input. This data is passed as a parameter to the function in `when`'s second parameter.
+3. A function that returns a boolean indicating whether to execute the action in `then`.
+
+The second and third parameters are the same as the parameters you previously passed to `when`.

www/apps/book/app/learn/fundamentals/workflows/constructor-constraints/page.mdx

@@ -157,6 +157,8 @@ const myWorkflow = createWorkflow(
 })
 ```
 
+You can also pair multiple `when-then` blocks to implement an `if-else` condition as explained in [this chapter](../conditions/page.mdx).
+
 ### No Conditional Operators
 
 You can't use conditional operators in a workflow, such as `??` or `||`.