diff --git a/lib/ash/changeset/changeset.ex b/lib/ash/changeset/changeset.ex
index cc6adca2..b7f03afd 100644
--- a/lib/ash/changeset/changeset.ex
+++ b/lib/ash/changeset/changeset.ex
@@ -351,30 +351,6 @@ defmodule Ash.Changeset do
   end
 
   @for_create_opts [
-    relationships: [
-      type: :any,
-      doc: """
-      customize relationship behavior.
-
-      By default, any relationships are ignored. There are three ways to change relationships with this function:
-
-      ### Action Arguments (preferred)
-
-      Create an argument on the action and add a `Ash.Resource.Change.Builtins.manage_relationship/3` change to the action.
-
-      ### Overrides
-
-      You can pass the `relationships` option to specify the behavior. It is a keyword list of relationship and either
-        * one of the preset manage types: #{inspect(@manage_types)}
-        * explicit options, in the form of `{:manage, [...opts]}`
-
-      ```elixir
-      Ash.Changeset.for_create(MyResource, :create, params, relationships: [relationship: :append, other_relationship: {:manage, [...opts]}])
-      ```
-
-      You can also use explicit calls to `manage_relationship/4`.
-      """
-    ],
     require?: [
       type: :boolean,
       default: false,
@@ -532,7 +508,7 @@ defmodule Ash.Changeset do
           |> set_tenant(opts[:tenant] || changeset.tenant)
           |> Map.put(:__validated_for_action__, action.name)
           |> Map.put(:action, action)
-          |> cast_params(action, params, opts)
+          |> cast_params(action, params)
           |> set_argument_defaults(action)
           |> run_action_changes(action, opts[:actor])
           |> add_validations()
@@ -560,7 +536,7 @@ defmodule Ash.Changeset do
           |> set_tenant(opts[:tenant] || changeset.tenant || changeset.data.__metadata__[:tenant])
           |> Map.put(:action, action)
           |> Map.put(:__validated_for_action__, action.name)
-          |> cast_params(action, params || %{}, opts)
+          |> cast_params(action, params || %{})
           |> set_argument_defaults(action)
           |> validate_attributes_accepted(action)
           |> require_values(action.type, false, action.require_attributes)
@@ -767,7 +743,7 @@ defmodule Ash.Changeset do
     end
   end
 
-  defp cast_params(changeset, action, params, opts) do
+  defp cast_params(changeset, action, params) do
     changeset = %{
       changeset
       | params: Map.merge(changeset.params || %{}, Enum.into(params || %{}, %{}))
@@ -785,24 +761,6 @@ defmodule Ash.Changeset do
             changeset
           end
 
-        rel = Ash.Resource.Info.public_relationship(changeset.resource, name) ->
-          if rel.writable? do
-            behaviour = opts[:relationships][rel.name]
-
-            case behaviour do
-              nil ->
-                changeset
-
-              type when is_atom(type) ->
-                manage_relationship(changeset, rel.name, value, type: type)
-
-              {:manage, manage_opts} ->
-                manage_relationship(changeset, rel.name, value, manage_opts)
-            end
-          else
-            changeset
-          end
-
         true ->
           changeset
       end
@@ -1568,11 +1526,6 @@ defmodule Ash.Changeset do
             * belongs_to - an update action on the source resource
       """
     ],
-    relationships: [
-      type: :any,
-      default: [],
-      doc: "A keyword list of instructions for nested relationships."
-    ],
     error_path: [
       type: :any,
       doc: """
@@ -1778,15 +1731,6 @@ defmodule Ash.Changeset do
 
         add_error(changeset, error)
 
-      %{writable?: false} = relationship ->
-        error =
-          InvalidRelationship.exception(
-            relationship: relationship.name,
-            message: "Relationship is not editable"
-          )
-
-        add_error(changeset, error)
-
       relationship ->
         if relationship.cardinality == :many && is_map(input) && !is_struct(input) do
           case map_input_to_list(input) do
diff --git a/lib/ash/dsl/dsl.ex b/lib/ash/dsl/dsl.ex
index e2503dfc..b12f4283 100644
--- a/lib/ash/dsl/dsl.ex
+++ b/lib/ash/dsl/dsl.ex
@@ -159,7 +159,18 @@ defmodule Ash.Dsl do
 
             defmacro __after_compile__(_, _) do
               quote do
-                Ash.Dsl.Extension.run_after_compile()
+                transformers_to_run =
+                  @extensions
+                  |> Enum.flat_map(& &1.transformers())
+                  |> Ash.Dsl.Transformer.sort()
+                  |> Enum.filter(& &1.after_compile?())
+
+                __MODULE__
+                |> Ash.Dsl.Extension.run_transformers(
+                  transformers_to_run,
+                  Module.get_attribute(__MODULE__, :ash_dsl_config),
+                  false
+                )
               end
             end
 
diff --git a/lib/ash/dsl/extension.ex b/lib/ash/dsl/extension.ex
index 5cbe3c51..85c0bed9 100644
--- a/lib/ash/dsl/extension.ex
+++ b/lib/ash/dsl/extension.ex
@@ -484,23 +484,6 @@ defmodule Ash.Dsl.Extension do
     end
   end
 
-  defmacro run_after_compile do
-    quote do
-      transformers_to_run =
-        @extensions
-        |> Enum.flat_map(& &1.transformers())
-        |> Ash.Dsl.Transformer.sort()
-        |> Enum.filter(& &1.after_compile?())
-
-      __MODULE__
-      |> Ash.Dsl.Extension.run_transformers(
-        transformers_to_run,
-        Module.get_attribute(__MODULE__, :ash_dsl_config),
-        false
-      )
-    end
-  end
-
   def run_transformers(mod, transformers, ash_dsl_config, store?) do
     Enum.reduce_while(transformers, ash_dsl_config, fn transformer, dsl ->
       result =
diff --git a/lib/ash/elixir_sense/plugin.ex b/lib/ash/elixir_sense/plugin.ex
index 738352af..d43e72ae 100644
--- a/lib/ash/elixir_sense/plugin.ex
+++ b/lib/ash/elixir_sense/plugin.ex
@@ -10,6 +10,7 @@ if Code.ensure_loaded?(ElixirSense.Plugin) do
     alias ElixirSense.Providers.Suggestion.Matcher
 
     def suggestions(hint, {_, function_call, arg_index, info}, _chain, opts) do
+      opts = add_module_store(opts)
       option = info.option || get_option(opts.cursor_context.text_before)
 
       if option do
@@ -20,6 +21,7 @@ if Code.ensure_loaded?(ElixirSense.Plugin) do
     end
 
     def suggestions(hint, opts) do
+      opts = add_module_store(opts)
       option = get_section_option(opts.cursor_context.text_before)
 
       if option do
@@ -29,6 +31,22 @@ if Code.ensure_loaded?(ElixirSense.Plugin) do
       end
     end
 
+    # For some reason, the module store does not change when modules are defined
+    # so we are building our own fresh copy here. This is definitely a performance
+    # hit
+    defp add_module_store(opts) do
+      Map.put(opts, :module_store, ElixirSense.Core.ModuleStore.build(all_loaded()))
+    end
+
+    defp all_loaded do
+      :code.all_loaded()
+      |> Enum.filter(fn
+        {mod, _} when is_atom(mod) -> true
+        _ -> false
+      end)
+      |> Enum.map(&elem(&1, 0))
+    end
+
     def get_suggestions(hint, opts, opt_path \\ [], type \\ nil) do
       with true <- Enum.any?(opts.env.attributes, &(&1.name == :ash_is)),
            dsl_mod when not is_nil(dsl_mod) <-
@@ -587,7 +605,14 @@ if Code.ensure_loaded?(ElixirSense.Plugin) do
       end)
       |> Enum.uniq()
       |> Enum.map(&Module.concat([&1]))
-      |> Enum.filter(&Code.ensure_loaded?/1)
+      |> Enum.filter(fn module ->
+        try do
+          Code.ensure_loaded?(module)
+        rescue
+          _ ->
+            false
+        end
+      end)
     end
   end
 end
diff --git a/lib/ash/elixir_sense/resource.ex b/lib/ash/elixir_sense/resource.ex
index f9587705..01fab267 100644
--- a/lib/ash/elixir_sense/resource.ex
+++ b/lib/ash/elixir_sense/resource.ex
@@ -30,6 +30,41 @@ if Code.ensure_loaded?(ElixirSense.Plugin) do
         else
           []
         end
+        |> Enum.reject(fn
+          %{name: name} when name in ["__info__", "module_info", "module_info"] ->
+            true
+
+          _ ->
+            false
+        end)
+        |> Enum.map(fn
+          %{type: :function, origin: origin, name: name, arity: arity} = completion ->
+            try do
+              {:docs_v1, _, _, _, _, _, functions} = Code.fetch_docs(Module.concat([origin]))
+
+              new_summary =
+                Enum.find_value(functions, fn
+                  {{:function, func_name, func_arity}, _, _,
+                   %{
+                     "en" => docs
+                   }, _} ->
+                    if to_string(func_name) == name && func_arity == arity do
+                      docs
+                    end
+
+                  _other ->
+                    false
+                end)
+
+              %{completion | summary: new_summary || completion.summary}
+            rescue
+              _e ->
+                completion
+            end
+
+          other ->
+            other
+        end)
 
       custom =
         for module <- module_store.by_behaviour[behaviour] || [],
@@ -51,6 +86,8 @@ if Code.ensure_loaded?(ElixirSense.Plugin) do
       builtins ++ custom
     end
 
+    defp lowercase_string?(""), do: true
+
     defp lowercase_string?(string) do
       first = String.first(string)
       String.downcase(first) == first
diff --git a/lib/ash/resource/change/builtins.ex b/lib/ash/resource/change/builtins.ex
index 2203a643..6314795e 100644
--- a/lib/ash/resource/change/builtins.ex
+++ b/lib/ash/resource/change/builtins.ex
@@ -24,8 +24,8 @@ defmodule Ash.Resource.Change.Builtins do
 
   If a zero argument function is provided, it is called to determine the value.
 
-  If a tuple of `{:arg, :argument_name}` is provided, the value will be read from the argument if supplied.
-  If the argument is not supplied then nothing happens.
+  If a `arg(:arg_name)` is provided, the value will be read from the argument if supplied.
+  If the argument specified is not given to the action, then nothing happens.
   """
   def set_attribute(attribute, value) do
     {Ash.Resource.Change.SetAttribute, attribute: attribute, value: value}
diff --git a/lib/ash/resource/relationships/belongs_to.ex b/lib/ash/resource/relationships/belongs_to.ex
index f5420a58..a3819690 100644
--- a/lib/ash/resource/relationships/belongs_to.ex
+++ b/lib/ash/resource/relationships/belongs_to.ex
@@ -56,6 +56,12 @@ defmodule Ash.Resource.Relationships.BelongsTo do
 
   @opt_schema Ash.OptionsHelpers.merge_schemas(
                 [
+                  writable?: [
+                    type: :boolean,
+                    doc:
+                      "Whether or not the attribute created by this relationship will be marked with `writable?: true`.",
+                    default: false
+                  ],
                   primary_key?: [
                     type: :boolean,
                     default: false,
diff --git a/lib/ash/resource/relationships/has_many.ex b/lib/ash/resource/relationships/has_many.ex
index 5de45f8f..483bea17 100644
--- a/lib/ash/resource/relationships/has_many.ex
+++ b/lib/ash/resource/relationships/has_many.ex
@@ -8,7 +8,6 @@ defmodule Ash.Resource.Relationships.HasMany do
     :source_field,
     :source,
     :context,
-    :writable?,
     :description,
     :filter,
     :sort,
@@ -28,7 +27,6 @@ defmodule Ash.Resource.Relationships.HasMany do
           type: :has_many,
           cardinality: :many,
           source: Ash.Resource.t(),
-          writable?: boolean,
           read_action: atom,
           filter: Ash.Filter.t() | nil,
           no_fields?: boolean,
diff --git a/lib/ash/resource/relationships/has_one.ex b/lib/ash/resource/relationships/has_one.ex
index cbd0d8b3..ec2b08e3 100644
--- a/lib/ash/resource/relationships/has_one.ex
+++ b/lib/ash/resource/relationships/has_one.ex
@@ -9,7 +9,6 @@ defmodule Ash.Resource.Relationships.HasOne do
     :private?,
     :source_field,
     :allow_orphans?,
-    :writable?,
     :context,
     :description,
     :filter,
@@ -31,7 +30,6 @@ defmodule Ash.Resource.Relationships.HasOne do
           type: :has_one,
           cardinality: :one,
           source: Ash.Resource.t(),
-          writable?: boolean,
           name: atom,
           read_action: atom,
           no_fields?: boolean,
diff --git a/lib/ash/resource/relationships/many_to_many.ex b/lib/ash/resource/relationships/many_to_many.ex
index a336e54d..80dd707a 100644
--- a/lib/ash/resource/relationships/many_to_many.ex
+++ b/lib/ash/resource/relationships/many_to_many.ex
@@ -13,7 +13,6 @@ defmodule Ash.Resource.Relationships.ManyToMany do
     :not_found_message,
     :violation_message,
     :api,
-    :writable?,
     :private?,
     :sort,
     :read_action,
@@ -30,7 +29,6 @@ defmodule Ash.Resource.Relationships.ManyToMany do
           type: :many_to_many,
           cardinality: :many,
           source: Ash.Resource.t(),
-          writable?: boolean,
           private?: boolean,
           filter: Ash.Filter.t() | nil,
           read_action: atom,
diff --git a/lib/ash/resource/relationships/shared_options.ex b/lib/ash/resource/relationships/shared_options.ex
index 98eb42a1..bb1e29c7 100644
--- a/lib/ash/resource/relationships/shared_options.ex
+++ b/lib/ash/resource/relationships/shared_options.ex
@@ -26,11 +26,6 @@ defmodule Ash.Resource.Relationships.SharedOptions do
       doc:
         "The field on this resource that should match the `destination_field` on the related resource."
     ],
-    writable?: [
-      type: :boolean,
-      doc: "Whether or not the relationship may be edited.",
-      default: true
-    ],
     description: [
       type: :string,
       doc: "An optional description for the relationship"
diff --git a/lib/ash/resource/transformers/belongs_to_attribute.ex b/lib/ash/resource/transformers/belongs_to_attribute.ex
index d4252786..9cd1afbc 100644
--- a/lib/ash/resource/transformers/belongs_to_attribute.ex
+++ b/lib/ash/resource/transformers/belongs_to_attribute.ex
@@ -29,7 +29,7 @@ defmodule Ash.Resource.Transformers.BelongsToAttribute do
             else
               not relationship.required?
             end,
-          writable?: false,
+          writable?: relationship.writable?,
           private?: true,
           primary_key?: relationship.primary_key?
         )
diff --git a/test/actions/create_test.exs b/test/actions/create_test.exs
index 77b2a481..7913e5ad 100644
--- a/test/actions/create_test.exs
+++ b/test/actions/create_test.exs
@@ -692,18 +692,6 @@ defmodule Ash.Test.Actions.CreateTest do
   end
 
   describe "creating with required belongs_to relationships" do
-    test "allows creating with belongs_to relationship" do
-      author =
-        Author
-        |> new()
-        |> change_attribute(:bio, "best dude")
-        |> Api.create!()
-
-      ProfileWithBelongsTo
-      |> Ash.Changeset.for_create(:create, [author: author], relationships: [author: :replace])
-      |> Api.create!()
-    end
-
     test "does not allow creating without the required belongs_to relationship" do
       assert_raise Ash.Error.Invalid, ~r/relationship author is required/, fn ->
         ProfileWithBelongsTo
diff --git a/test/elixir_sense/plugin_test.exs b/test/elixir_sense/plugin_test.exs
index 2fb2a308..4498ca8c 100644
--- a/test/elixir_sense/plugin_test.exs
+++ b/test/elixir_sense/plugin_test.exs
@@ -543,7 +543,8 @@ defmodule Ash.ElixirSense.PluginTest do
                snippet: nil,
                spec: "",
                summary:
-                 "Calls `Ash.Changeset.manage_relationship/4` with the changeset and relationship provided, using the value provided for the named argument",
+                 "Calls `Ash.Changeset.manage_relationship/4` with the changeset and relationship provided, using the value provided for the named argument" <>
+                   _,
                type: :function,
                visibility: :public
              },
@@ -558,7 +559,8 @@ defmodule Ash.ElixirSense.PluginTest do
                snippet: nil,
                spec: "",
                summary:
-                 "Calls `Ash.Changeset.manage_relationship/4` with the changeset and relationship provided, using the value provided for the named argument",
+                 "Calls `Ash.Changeset.manage_relationship/4` with the changeset and relationship provided, using the value provided for the named argument" <>
+                   _,
                type: :function,
                visibility: :public
              }