yordis · Oct 28, 2025 · Oct 28, 2025
diff --git a/guides/explanations/events.md b/guides/explanations/events.md
@@ -223,38 +223,6 @@ You request the consistency guarantee, either `:strong` or `:eventual`, when dis
 
 An event handler is a `GenServer` process that subscribes to the configured event store. For each event persisted to the store the `handle/2` callback is called, passing the domain event and its metadata.
 
-## Upcasting events
-
-Commanded supports upcasting of events at runtime using the `Commanded.Event.Upcaster` protocol.
-
-By implementing the upcaster protocol you can transform an event before it is used by a consumer. This might be an aggregate or an event handler. Because the upcaster changes the event at runtime, handlers only need to support the latest version. You can also use upcasting to change the type of event.
-
-### Examples
-
-Change the shape of an event by renaming a field:
-
-```elixir
-defimpl Commanded.Event.Upcaster, for: AnEvent do
-  def upcast(%AnEvent{} = event, _metadata) do
-    %AnEvent{name: name} = event
-
-    %AnEvent{event | first_name: name}
-  end
-end
-```
-
-Change the type of event by replacing a historical event with a new event:
-
-```elixir
-defimpl Commanded.Event.Upcaster, for: HistoricalEvent do
-  def upcast(%HistoricalEvent{} = event, _metadata) do
-    %HistoricalEvent{id: id, name: name} = event
-
-    %NewEvent{id: id, name: name}
-  end
-end
-```
-
 ## Reset an EventHandler
 
 An event handler can be reset (using a mix task), it will restart the event store subscription from the configured

diff --git a/guides/explanations/fork-differences.md b/guides/explanations/fork-differences.md
@@ -11,9 +11,9 @@ This fork maintains an independent release cycle to introduce new features and i
 
 ---
 
-## Breaking Changes
+## Breaking Changes ❌
 
-### **Removed ProcessManager Support** ❌
+### **Removed ProcessManager Support**
 [PR #24](https://github.com/straw-hat-team/commanded/pull/24)
 
 **Changes:**
@@ -26,7 +26,18 @@ This fork maintains an independent release cycle to introduce new features and i
 
 ---
 
-### **EnrichedMetadata Struct** 🔄
+### **Removed Upcasting Support**
+
+**Changes:**
+- Removed `Commanded.Event.Upcast` and `Commanded.Event.Upcaster` modules
+- Removed upcasting from event handlers and aggregates
+- Removed upcasting documentation
+
+**Reason:** Event schema transformations can be handled explicitly in event handlers and aggregates using pattern matching, eliminating the need for a global upcasting component.
+
+---
+
+### **EnrichedMetadata Struct**
 [PR #11](https://github.com/straw-hat-team/commanded/pull/11)
 
 **Changes:**
@@ -37,9 +48,9 @@ This fork maintains an independent release cycle to introduce new features and i
 
 ---
 
-## Features Added
+## Features Added ✨
 
-### **UUIDv7 Support** ✨
+### **UUIDv7 Support**
 [PR #22](https://github.com/straw-hat-team/commanded/pull/22)
 
 **Changes:**
@@ -48,7 +59,7 @@ This fork maintains an independent release cycle to introduce new features and i
 
 ---
 
-### **Configurable UUID Provider** ✨
+### **Configurable UUID Provider**
 
 **Changes:**
 - Integrated `Uniq.UUID` library for UUID generation
@@ -57,7 +68,7 @@ This fork maintains an independent release cycle to introduce new features and i
 
 ---
 
-### **Aggregate Telemetry for Version Conflicts** ✨
+### **Aggregate Telemetry for Version Conflicts**
 [PR #8](https://github.com/straw-hat-team/commanded/pull/8)
 
 **Changes:**
@@ -66,7 +77,7 @@ This fork maintains an independent release cycle to introduce new features and i
 
 ---
 
-### **Custom Event ID Support** ✨
+### **Custom Event ID Support**
 [PR #2](https://github.com/straw-hat-team/commanded/pull/2)
 
 **Changes:**
@@ -76,7 +87,7 @@ This fork maintains an independent release cycle to introduce new features and i
 
 ---
 
-### **EventStore Adapter** ✨
+### **EventStore Adapter**
 [PR #1](https://github.com/straw-hat-team/commanded/pull/1)
 
 **Changes:**

diff --git a/guides/howtos/migrating-from-v1-to-v2.md b/guides/howtos/migrating-from-v1-to-v2.md
@@ -94,18 +94,6 @@ end
    end
    ```
 
-4. **Update Upcaster implementations:**
-
-   ```elixir
-   defimpl Commanded.Event.Upcaster, for: MyEvent do
-     alias Commanded.EventStore.EnrichedMetadata
-
-     def upcast(event, %EnrichedMetadata{} = metadata) do
-       # Implementation
-     end
-   end
-   ```
-
 ## System Metadata Fields
 
 The following fields are now directly accessible on the `EnrichedMetadata` struct:

diff --git a/lib/commanded/aggregates/aggregate.ex b/lib/commanded/aggregates/aggregate.ex
@@ -119,7 +119,6 @@ defmodule Commanded.Aggregates.Aggregate do
   alias Commanded.Aggregates.ExecutionContext
   alias Commanded.Application.Config
   alias Commanded.Event.Mapper
-  alias Commanded.Event.Upcast
   alias Commanded.EventStore
   alias Commanded.EventStore.RecordedEvent
   alias Commanded.Registration
@@ -392,15 +391,12 @@ defmodule Commanded.Aggregates.Aggregate do
   @doc false
   @impl GenServer
   def handle_info({:events, events}, %Aggregate{} = state) do
-    %Aggregate{application: application} = state
-
     Logger.debug(describe(state) <> " received events: " <> inspect(events))
 
     try do
       state =
         events
         |> Enum.reject(&event_already_seen?(&1, state))
-        |> Upcast.upcast_event_stream(additional_metadata: %{application: application})
         |> Enum.reduce(state, &handle_event/2)
 
       noreply_with_lifespan(state)

diff --git a/lib/commanded/event/handler.ex b/lib/commanded/event/handler.ex
@@ -407,7 +407,6 @@ defmodule Commanded.Event.Handler do
   alias Commanded.Event.ErrorHandler
   alias Commanded.Event.FailureContext
   alias Commanded.Event.Handler
-  alias Commanded.Event.Upcast
   alias Commanded.EventStore.RecordedEvent
   alias Commanded.EventStore.Subscription
   alias Commanded.Subscriptions
@@ -952,7 +951,7 @@ defmodule Commanded.Event.Handler do
   @doc false
   @impl GenServer
   def handle_info({:events, events}, state) do
-    %Handler{application: application, handler_callback: callback} = state
+    %Handler{handler_callback: callback} = state
 
     processor =
       case callback do
@@ -963,10 +962,7 @@ defmodule Commanded.Event.Handler do
     Logger.debug(describe(state) <> " received events: #{inspect(events)}")
 
     try do
-      state =
-        events
-        |> Upcast.upcast_event_stream(additional_metadata: %{application: application})
-        |> processor.(state)
+      state = processor.(events, state)
 
       {:noreply, state}
     catch
@@ -1417,8 +1413,7 @@ defmodule Commanded.Event.Handler do
          handler_name,
          handler_module
        ) do
-    %RecordedEvent{data: data} =
-      event = Upcast.upcast_event(event, additional_metadata: %{application: application})
+    %RecordedEvent{data: data} = event
 
     metadata =
       RecordedEvent.enrich_metadata(event,

diff --git a/lib/commanded/event/upcast.ex b/lib/commanded/event/upcast.ex
diff --git a/lib/commanded/event/upcaster.ex b/lib/commanded/event/upcaster.ex
diff --git a/lib/commanded/event_store.ex b/lib/commanded/event_store.ex
@@ -25,7 +25,6 @@ defmodule Commanded.EventStore do
 
   """
   alias Commanded.Application
-  alias Commanded.Event.Upcast
 
   @type application :: Application.t()
   @type config :: Keyword.t()
@@ -80,7 +79,7 @@ defmodule Commanded.EventStore do
           error
 
         stream ->
-          Upcast.upcast_event_stream(stream, additional_metadata: %{application: application})
+          stream
       end
     end)
   end

diff --git a/mix.exs b/mix.exs
@@ -131,7 +131,6 @@ defmodule Commanded.Mixfile do
           Commanded.Event.FailureContext,
           Commanded.Event.Handler,
           Commanded.Event.Mapper,
-          Commanded.Event.Upcaster,
           Commanded.Event.EventId
         ],
         "Event Store": [

diff --git a/test/event/support/upcast/batch_event_handler.ex b/test/event/support/upcast/batch_event_handler.ex
diff --git a/test/event/support/upcast/event_handler.ex b/test/event/support/upcast/event_handler.ex