diff --git a/AGENTS.md b/AGENTS.md
index 3a359a0..615dc1b 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -331,8 +331,9 @@ not. Add any useful hypotheses as a follow-up comment on the issue, then leave i
 - Using `characteristic :name, Diffo.Provider.AssignableCharacteristic` for pools — use `pools do / pool :name, :thing / end` instead.
 - Using the removed `AssignableValue` TypedStruct — it no longer exists; use `pools do`.
 - Calling `Assigner.assign/4` when a `pools do` declaration exists — prefer `Assigner.assign/3` which looks up the thing automatically.
-- Forgetting to call `Pool.update_pools/3` in `:define` actions when the resource has `pools do` — pool bounds (`first`, `last`, `algorithm`) are set here.
-- Calling `Assigner.assign/3` on an instance that is not in the correct lifecycle state — the assigner enforces: resource instances must have `resource_state: :operating`; service instances must have `service_state: :active` or `:inactive`. Lifecycle state transitions are an internal domain concern managed by the provider; assignment actions are external-facing. Future: consumer reads may filter out non-`:operating` resources entirely.
+- Hand-writing the `:define` / `:relate` / `:assign_*` after-action plumbing — use `Diffo.Provider.Changes.Define`, `Diffo.Provider.Changes.Relate`, and `{Diffo.Provider.Changes.Assign, pool: :name}` (since 0.4.1). The change modules thread `Characteristic.update_all/3`, `Pool.update_pools/3`, `Relationship.relate_instance/2` and `Assigner.assign/3` together and reload via the resource's primary `:read` action.
+- Hand-writing the `:create` / `:update` accept lists on a `BaseCharacteristic`-derived resource — they are synthesised from the resource's public attributes (since 0.4.1). Declare your own only when you need a narrower accept list.
+- Calling `Assigner.assign/3` on an instance that is not in the correct lifecycle state — the assigner enforces: resource instances must have `resource_state` of `:installing` or `:operating`; service instances must have `service_state` of `:feasibilityChecked`, `:reserved`, `:inactive`, `:active`, or `:suspended` (since 0.4.1). The full lists are exposed via `Assigner.assignable_resource_states/0` and `Assigner.assignable_service_states/0`. Lifecycle state transitions are an internal domain concern managed by the provider; assignment actions are external-facing.
 - Wondering why `Relationship` and `AssignmentRelationship` both have an `alias` attribute with a `[:source_id, :alias]` / `[:target_id, :alias]` identity — alias is a "baby name" given to a relationship slot before (or when) the target is bound. Its full purpose becomes clear alongside the first-order expectation system (see issue #122): the expectation declares the alias for a slot it expects to be filled, and the actual relationship carries the same alias so the two can be matched. Without expectations in place, aliases look like optional metadata; with them, they are the join key between intent and fulfilment.
 - Using `characteristic :pool_name, Diffo.Provider.AssignedToRelationship` — `AssignedToRelationship` no longer exists; use `pools do / pool :name, :thing / end` instead.
 - Querying `Diffo.Provider.Relationship` for assignment records — assignments are stored as `Diffo.Provider.DefinedSimpleRelationship`; access them via `instance.assignments`.
diff --git a/CHANGELOG.md b/CHANGELOG.md
index c438506..1760d8f 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -11,6 +11,42 @@ See [Conventional Commits](Https://conventionalcommits.org) for commit guideline
 
 <!-- changelog -->
 
+## [v0.4.1](https://github.com/diffo-dev/diffo/compare/v0.4.0...v0.4.1) (2026-05-22)
+
+### Bug Fixes
+
+* **Assigner lifecycle** (#168) — broadened the lifecycle states permitted to make assignments. Services may now assign from `:feasibilityChecked`, `:reserved`, `:inactive`, `:active`, or `:suspended` (was `:active` / `:inactive` only). Resources may now assign from `:installing` or `:operating` (was `:operating` only). `Assigner.assignable_state?/1` exposes the policy directly.
+
+### Features
+
+* **`Diffo.Provider.Changes.Define` / `Relate` / `Assign`** (#170) — change modules that wrap the standard after-action patterns every Instance consumer writes. Replace the hand-written `after_action` body threading `Characteristic.update_all` / `Pool.update_pools` / `Relationship.relate_instance` / `Assigner.assign` together with a one-liner:
+
+  ```elixir
+  update :define do
+    argument :characteristic_value_updates, {:array, :term}
+    change Diffo.Provider.Changes.Define
+  end
+
+  update :relate do
+    argument :relationships, {:array, :struct}
+    change Diffo.Provider.Changes.Relate
+  end
+
+  update :assign_port do
+    argument :assignment, :struct, constraints: [instance_of: Assignment]
+    change {Diffo.Provider.Changes.Assign, pool: :ports}
+  end
+  ```
+
+  Reload happens via the resource's primary `:read` action, so no consumer-specific reader is needed.
+* **BaseCharacteristic auto-generated `:create` / `:update` actions** (#171) — `BaseCharacteristic`-derived resources now get default `:create` and `:update` actions synthesised from their public attributes. `:create` accepts `[:name | <public_attrs>]` with `:instance_id` / `:feature_id` arguments and `manage_relationship` changes; `:update` accepts `<public_attrs>`. Consumers may still declare their own actions to override the defaults.
+* **Typed characteristics and pools in Instance JSON** (#169) — `BaseInstance` now loads two new calculations (`:typed_characteristics`, `:pool_characteristics`) by default and the jason customize merges their values into the `serviceCharacteristic` / `resourceCharacteristic` array. Typed `BaseCharacteristic` records and `AssignableCharacteristic` pool records that were already present in the graph are now visible at the TMF JSON surface.
+
+### Notable Changes
+
+* `Diffo.Provider.Calculations.TypedCharacteristics` and `Diffo.Provider.Calculations.PoolCharacteristics` — new calc modules backing the JSON surfacing for #169.
+* Regression test added for #62 (characteristic update validation) — typed `BaseCharacteristic` updates now reject unknown fields and invalid types through Ash's standard changeset machinery.
+
 ## [v0.4.0](https://github.com/diffo-dev/diffo/compare/v0.3.0...v0.4.0) (2026-05-20)
 
 ### Breaking Changes
diff --git a/lib/diffo/provider/changes/assign.ex b/lib/diffo/provider/changes/assign.ex
new file mode 100644
index 0000000..1c55222
--- /dev/null
+++ b/lib/diffo/provider/changes/assign.ex
@@ -0,0 +1,56 @@
+# SPDX-FileCopyrightText: 2025 diffo contributors <https://github.com/diffo-dev/diffo/graphs.contributors>
+#
+# SPDX-License-Identifier: MIT
+
+defmodule Diffo.Provider.Changes.Assign do
+  @moduledoc """
+  After-action change for the standard `:assign_*` pattern.
+
+  Performs an assignment for the named pool via `Assigner.assign/3`, then
+  reloads the result via the resource's primary `:read` action.
+
+  ## Usage
+
+      update :assign_port do
+        argument :assignment, :struct, constraints: [instance_of: Assignment]
+        change {Diffo.Provider.Changes.Assign, pool: :ports}
+      end
+
+  ## Options
+
+  - `:pool` (required) — the pool name (atom) declared via `pools do` on the
+    consuming instance resource.
+  """
+  use Ash.Resource.Change
+
+  require Ash.Query
+
+  alias Diffo.Provider.Assigner
+
+  @impl true
+  def init(opts) do
+    case Keyword.fetch(opts, :pool) do
+      {:ok, pool} when is_atom(pool) and not is_nil(pool) ->
+        {:ok, opts}
+
+      _ ->
+        {:error, "Diffo.Provider.Changes.Assign requires a :pool atom option"}
+    end
+  end
+
+  @impl true
+  def change(changeset, opts, _context) do
+    pool = Keyword.fetch!(opts, :pool)
+
+    Ash.Changeset.after_action(changeset, fn changeset, result ->
+      with {:ok, result} <- Assigner.assign(result, changeset, pool) do
+        id = result.id
+
+        changeset.resource
+        |> Ash.Query.for_read(:read)
+        |> Ash.Query.filter(id == ^id)
+        |> Ash.read_one()
+      end
+    end)
+  end
+end
diff --git a/lib/diffo/provider/changes/define.ex b/lib/diffo/provider/changes/define.ex
new file mode 100644
index 0000000..c33c314
--- /dev/null
+++ b/lib/diffo/provider/changes/define.ex
@@ -0,0 +1,49 @@
+# SPDX-FileCopyrightText: 2025 diffo contributors <https://github.com/diffo-dev/diffo/graphs.contributors>
+#
+# SPDX-License-Identifier: MIT
+
+defmodule Diffo.Provider.Changes.Define do
+  @moduledoc """
+  After-action change for the standard `:define` pattern.
+
+  Applies `characteristic_value_updates` to the instance's declared typed and
+  dynamic characteristics (`Characteristic.update_all/3`) and to its declared
+  pools (`Pool.update_pools/3`), then reloads the result via the resource's
+  primary `:read` action.
+
+  ## Usage
+
+      update :define do
+        argument :characteristic_value_updates, {:array, :term}
+        change Diffo.Provider.Changes.Define
+      end
+
+  This replaces the hand-written `after_action` block that threads
+  `characteristics()`, `pools()`, `Characteristic.update_all/3` and
+  `Pool.update_pools/3` together on every consumer.
+  """
+  use Ash.Resource.Change
+
+  require Ash.Query
+
+  alias Diffo.Provider.Extension.Characteristic
+  alias Diffo.Provider.Extension.Pool
+
+  @impl true
+  def change(changeset, _opts, _context) do
+    Ash.Changeset.after_action(changeset, fn changeset, result ->
+      module = changeset.resource
+
+      with {:ok, result} <- Ash.load(result, [:characteristics]),
+           {:ok, result} <- Characteristic.update_all(result, changeset, module.characteristics()),
+           {:ok, result} <- Pool.update_pools(result, changeset, module.pools()) do
+        id = result.id
+
+        module
+        |> Ash.Query.for_read(:read)
+        |> Ash.Query.filter(id == ^id)
+        |> Ash.read_one()
+      end
+    end)
+  end
+end
diff --git a/lib/diffo/provider/changes/relate.ex b/lib/diffo/provider/changes/relate.ex
new file mode 100644
index 0000000..a3dd61f
--- /dev/null
+++ b/lib/diffo/provider/changes/relate.ex
@@ -0,0 +1,39 @@
+# SPDX-FileCopyrightText: 2025 diffo contributors <https://github.com/diffo-dev/diffo/graphs.contributors>
+#
+# SPDX-License-Identifier: MIT
+
+defmodule Diffo.Provider.Changes.Relate do
+  @moduledoc """
+  After-action change for the standard `:relate` pattern.
+
+  Creates relationships from the `:relationships` argument on the changeset via
+  `Relationship.relate_instance/2`, then reloads the result via the resource's
+  primary `:read` action.
+
+  ## Usage
+
+      update :relate do
+        argument :relationships, {:array, :struct}
+        change Diffo.Provider.Changes.Relate
+      end
+  """
+  use Ash.Resource.Change
+
+  require Ash.Query
+
+  alias Diffo.Provider.Instance.Relationship
+
+  @impl true
+  def change(changeset, _opts, _context) do
+    Ash.Changeset.after_action(changeset, fn changeset, result ->
+      with {:ok, result} <- Relationship.relate_instance(result, changeset) do
+        id = result.id
+
+        changeset.resource
+        |> Ash.Query.for_read(:read)
+        |> Ash.Query.filter(id == ^id)
+        |> Ash.read_one()
+      end
+    end)
+  end
+end
diff --git a/lib/diffo/provider/components/base_instance.ex b/lib/diffo/provider/components/base_instance.ex
index b58f8bc..99eb0bb 100644
--- a/lib/diffo/provider/components/base_instance.ex
+++ b/lib/diffo/provider/components/base_instance.ex
@@ -235,6 +235,7 @@ defmodule Diffo.Provider.BaseInstance do
         :features,
         Instance.derive_feature_list_name(record.type)
       )
+      |> Instance.merge_typed_and_pool_characteristics(record)
       |> Util.suppress_rename(
         :characteristics,
         Instance.derive_characteristic_list_name(record.type)
@@ -688,6 +689,8 @@ defmodule Diffo.Provider.BaseInstance do
                 :notes,
                 :features,
                 :characteristics,
+                :typed_characteristics,
+                :pool_characteristics,
                 :places,
                 :parties
               ],
@@ -699,5 +702,17 @@ defmodule Diffo.Provider.BaseInstance do
     calculate :href, :string, Diffo.Provider.Calculations.InstanceHref do
       description "the inventory href of the service or resource instance"
     end
+
+    calculate :typed_characteristics,
+              {:array, :struct},
+              Diffo.Provider.Calculations.TypedCharacteristics do
+      description "typed BaseCharacteristic records declared via the characteristics DSL"
+    end
+
+    calculate :pool_characteristics,
+              {:array, :struct},
+              Diffo.Provider.Calculations.PoolCharacteristics do
+      description "AssignableCharacteristic records declared via the pools DSL"
+    end
   end
 end
diff --git a/lib/diffo/provider/components/calculations/pool_characteristics.ex b/lib/diffo/provider/components/calculations/pool_characteristics.ex
new file mode 100644
index 0000000..796735b
--- /dev/null
+++ b/lib/diffo/provider/components/calculations/pool_characteristics.ex
@@ -0,0 +1,31 @@
+# SPDX-FileCopyrightText: 2025 diffo contributors <https://github.com/diffo-dev/diffo/graphs.contributors>
+#
+# SPDX-License-Identifier: MIT
+
+defmodule Diffo.Provider.Calculations.PoolCharacteristics do
+  @moduledoc """
+  Loads the `AssignableCharacteristic` pool records associated with an
+  instance, one per `pool :name, :thing` declaration on the resource module.
+
+  Used by `BaseInstance` to surface pool characteristics alongside the
+  dynamic `Diffo.Provider.Characteristic` records in the
+  `serviceCharacteristic` / `resourceCharacteristic` JSON view (#169).
+  """
+  use Ash.Resource.Calculation
+
+  @impl true
+  def load(_query, _opts, _context), do: []
+
+  @impl true
+  def calculate(records, _opts, _context) do
+    Enum.map(records, fn record ->
+      if function_exported?(record.__struct__, :pools, 0) and record.__struct__.pools() != [] do
+        Diffo.Provider.AssignableCharacteristic
+        |> Ash.Query.filter_input(instance_id: record.id)
+        |> Ash.read!(domain: Diffo.Provider)
+      else
+        []
+      end
+    end)
+  end
+end
diff --git a/lib/diffo/provider/components/calculations/typed_characteristics.ex b/lib/diffo/provider/components/calculations/typed_characteristics.ex
new file mode 100644
index 0000000..36ea0ad
--- /dev/null
+++ b/lib/diffo/provider/components/calculations/typed_characteristics.ex
@@ -0,0 +1,56 @@
+# SPDX-FileCopyrightText: 2025 diffo contributors <https://github.com/diffo-dev/diffo/graphs.contributors>
+#
+# SPDX-License-Identifier: MIT
+
+defmodule Diffo.Provider.Calculations.TypedCharacteristics do
+  @moduledoc """
+  Loads all typed `BaseCharacteristic`-derived records associated with an
+  instance.
+
+  For each `characteristic :role, ValueModule` declaration on the instance's
+  resource module — including both singular and `{:array, ValueModule}` forms
+  — this calculation queries `ValueModule` by `instance_id == record.id` and
+  returns the collected records as a flat list.
+
+  Used by `BaseInstance` to surface typed characteristics alongside the
+  dynamic `Diffo.Provider.Characteristic` records in the
+  `serviceCharacteristic` / `resourceCharacteristic` JSON view (#169).
+  """
+  use Ash.Resource.Calculation
+
+  alias Diffo.Provider.Extension.Characteristic, as: CharacteristicHelper
+
+  @impl true
+  def load(_query, _opts, _context), do: []
+
+  @impl true
+  def calculate(records, _opts, _context) do
+    Enum.map(records, fn record ->
+      record
+      |> typed_value_modules()
+      |> Enum.flat_map(fn module ->
+        module
+        |> Ash.Query.filter_input(instance_id: record.id)
+        |> Ash.read!(domain: Diffo.Provider)
+      end)
+    end)
+  end
+
+  defp typed_value_modules(record) do
+    module = record.__struct__
+
+    if function_exported?(module, :characteristics, 0) do
+      module.characteristics()
+      |> Enum.map(fn %{value_type: value_type} ->
+        case value_type do
+          {:array, mod} -> mod
+          mod when is_atom(mod) -> mod
+        end
+      end)
+      |> Enum.uniq()
+      |> Enum.filter(&CharacteristicHelper.typed?/1)
+    else
+      []
+    end
+  end
+end
diff --git a/lib/diffo/provider/components/characteristic/extension.ex b/lib/diffo/provider/components/characteristic/extension.ex
index a5f4046..16561f8 100644
--- a/lib/diffo/provider/components/characteristic/extension.ex
+++ b/lib/diffo/provider/components/characteristic/extension.ex
@@ -3,6 +3,18 @@
 # SPDX-License-Identifier: MIT
 
 defmodule Diffo.Provider.Characteristic.Extension do
-  @moduledoc "Marker extension identifying a module as a valid characteristic resource."
-  use Spark.Dsl.Extension, sections: []
+  @moduledoc """
+  Marker extension identifying a module as a valid characteristic resource.
+
+  Also synthesises default `:create` and `:update` actions on
+  `BaseCharacteristic`-derived resources from the resource's declared public
+  attributes — `:create` accepts `[:name | <public_attrs>]` with
+  `:instance_id` / `:feature_id` arguments and corresponding
+  `manage_relationship` changes; `:update` accepts `<public_attrs>` only.
+  Consumers may declare their own `:create` / `:update` actions to override
+  the synthesised ones.
+  """
+  use Spark.Dsl.Extension,
+    sections: [],
+    transformers: [Diffo.Provider.Characteristic.Extension.Transformers.GenerateActions]
 end
diff --git a/lib/diffo/provider/components/characteristic/extension/transformers/generate_actions.ex b/lib/diffo/provider/components/characteristic/extension/transformers/generate_actions.ex
new file mode 100644
index 0000000..755b9d5
--- /dev/null
+++ b/lib/diffo/provider/components/characteristic/extension/transformers/generate_actions.ex
@@ -0,0 +1,71 @@
+# SPDX-FileCopyrightText: 2025 diffo contributors <https://github.com/diffo-dev/diffo/graphs.contributors>
+#
+# SPDX-License-Identifier: MIT
+
+defmodule Diffo.Provider.Characteristic.Extension.Transformers.GenerateActions do
+  @moduledoc """
+  Synthesises default `:create` and `:update` actions on
+  `BaseCharacteristic`-derived resources from the resource's declared public
+  attributes.
+
+  `:create` accepts `[:name | <public_attrs>]` with `:instance_id` and
+  `:feature_id` `:uuid` arguments and corresponding `manage_relationship`
+  changes. `:update` accepts `<public_attrs>` only.
+
+  Consumers that declare their own `:create` or `:update` action take
+  precedence — `add_new_action/4` will not replace an existing one.
+
+  System attributes (`:id`, timestamps, the BaseCharacteristic `:name` slot)
+  are excluded from the synthesised lists; `:name` is included on `:create`
+  only.
+  """
+  use Spark.Dsl.Transformer
+
+  alias Ash.Resource.Builder
+  alias Spark.Dsl.Transformer
+
+  # Attributes generated by Ash internals / BaseCharacteristic that must not
+  # appear in the synthesised accept lists.
+  @reserved_attrs [:id, :name, :created_at, :updated_at]
+
+  @impl true
+  def transform(dsl_state) do
+    public_attrs = consumer_public_attributes(dsl_state)
+
+    with {:ok, dsl_state} <- maybe_add_create(dsl_state, public_attrs) do
+      maybe_add_update(dsl_state, public_attrs)
+    end
+  end
+
+  defp consumer_public_attributes(dsl_state) do
+    dsl_state
+    |> Transformer.get_entities([:attributes])
+    |> Enum.filter(&(Map.get(&1, :public?) && &1.name not in @reserved_attrs))
+    |> Enum.map(& &1.name)
+  end
+
+  defp maybe_add_create(dsl_state, public_attrs) do
+    with {:ok, instance_arg} <- Builder.build_action_argument(:instance_id, :uuid),
+         {:ok, feature_arg} <- Builder.build_action_argument(:feature_id, :uuid),
+         {:ok, instance_change} <-
+           Builder.build_action_change(
+             {Ash.Resource.Change.ManageRelationship,
+              [argument: :instance_id, relationship: :instance, opts: [type: :append]]}
+           ),
+         {:ok, feature_change} <-
+           Builder.build_action_change(
+             {Ash.Resource.Change.ManageRelationship,
+              [argument: :feature_id, relationship: :feature, opts: [type: :append]]}
+           ) do
+      Builder.add_new_action(dsl_state, :create, :create,
+        accept: [:name | public_attrs],
+        arguments: [instance_arg, feature_arg],
+        changes: [instance_change, feature_change]
+      )
+    end
+  end
+
+  defp maybe_add_update(dsl_state, public_attrs) do
+    Builder.add_new_action(dsl_state, :update, :update, accept: public_attrs)
+  end
+end
diff --git a/lib/diffo/provider/components/instance/util.ex b/lib/diffo/provider/components/instance/util.ex
index 0e20761..09902ed 100644
--- a/lib/diffo/provider/components/instance/util.ex
+++ b/lib/diffo/provider/components/instance/util.ex
@@ -124,6 +124,22 @@ defmodule Diffo.Provider.Instance.Util do
     end
   end
 
+  @doc false
+  def merge_typed_and_pool_characteristics(result, record) do
+    typed = Map.get(record, :typed_characteristics) || []
+    pool = Map.get(record, :pool_characteristics) || []
+    extras = typed ++ pool
+
+    case extras do
+      [] ->
+        result
+
+      _ ->
+        existing = Diffo.Util.get(result, :characteristics) || []
+        Diffo.Util.set(result, :characteristics, existing ++ extras)
+    end
+  end
+
   @doc false
   def derive_type(specification_type) do
     case specification_type do
diff --git a/mix.exs b/mix.exs
index 5bc13cd..be6dc83 100644
--- a/mix.exs
+++ b/mix.exs
@@ -6,7 +6,7 @@ defmodule Diffo.MixProject do
   @moduledoc false
   use Mix.Project
 
-  @version "0.4.0"
+  @version "0.4.1"
   @name "Diffo"
   @description "TMF Service and Resource Manager with a difference"
   @github_url "https://github.com/diffo-dev/diffo"
diff --git a/test/provider/extension/assigner_test.exs b/test/provider/extension/assigner_test.exs
index 5e662a2..8969fc8 100644
--- a/test/provider/extension/assigner_test.exs
+++ b/test/provider/extension/assigner_test.exs
@@ -105,7 +105,7 @@ defmodule Diffo.Provider.Extension.AssignerTest do
       encoding = Jason.encode!(card) |> Diffo.Util.summarise_dates()
 
       assert encoding ==
-               ~s({\"id\":\"#{card.id}",\"href\":\"resourceInventoryManagement/v4/resource/#{card.id}",\"category\":\"Network Resource\",\"description\":\"A Card Resource Instance\",\"resourceSpecification\":{\"id\":\"cd29956f-6c68-44cc-bf54-705eb8d2f754\",\"href\":\"resourceCatalogManagement/v4/resourceSpecification/cd29956f-6c68-44cc-bf54-705eb8d2f754\",\"name\":\"card\",\"version\":\"v1.0.0\"}})
+               ~s({\"id\":\"#{card.id}",\"href\":\"resourceInventoryManagement/v4/resource/#{card.id}",\"category\":\"Network Resource\",\"description\":\"A Card Resource Instance\",\"resourceSpecification\":{\"id\":\"cd29956f-6c68-44cc-bf54-705eb8d2f754\",\"href\":\"resourceCatalogManagement/v4/resourceSpecification/cd29956f-6c68-44cc-bf54-705eb8d2f754\",\"name\":\"card\",\"version\":\"v1.0.0\"},\"resourceCharacteristic\":[{\"name\":\"card\",\"value\":{}},{\"name\":\"ports\",\"value\":{\"first\":1,\"last\":1,\"algorithm\":\"lowest\"}}]})
     end
 
     test "define card" do
@@ -131,7 +131,7 @@ defmodule Diffo.Provider.Extension.AssignerTest do
       encoding = Jason.encode!(card) |> Diffo.Util.summarise_dates()
 
       assert encoding ==
-               ~s({\"id\":\"#{card.id}",\"href\":\"resourceInventoryManagement/v4/resource/#{card.id}",\"category\":\"Network Resource\",\"description\":\"A Card Resource Instance\",\"resourceSpecification\":{\"id\":\"cd29956f-6c68-44cc-bf54-705eb8d2f754\",\"href\":\"resourceCatalogManagement/v4/resourceSpecification/cd29956f-6c68-44cc-bf54-705eb8d2f754\",\"name\":\"card\",\"version\":\"v1.0.0\"}})
+               ~s({\"id\":\"#{card.id}",\"href\":\"resourceInventoryManagement/v4/resource/#{card.id}",\"category\":\"Network Resource\",\"description\":\"A Card Resource Instance\",\"resourceSpecification\":{\"id\":\"cd29956f-6c68-44cc-bf54-705eb8d2f754\",\"href\":\"resourceCatalogManagement/v4/resourceSpecification/cd29956f-6c68-44cc-bf54-705eb8d2f754\",\"name\":\"card\",\"version\":\"v1.0.0\"},\"resourceCharacteristic\":[{\"name\":\"card\",\"value\":{\"family\":\"ISAM\",\"model\":\"EBLT48\",\"technology\":\"adsl2Plus\"}},{\"name\":\"ports\",\"value\":{\"first\":1,\"last\":48,\"type\":\"ADSL2+\",\"algorithm\":\"lowest\"}}]})
     end
 
     test "auto assign port to resource" do
@@ -157,7 +157,7 @@ defmodule Diffo.Provider.Extension.AssignerTest do
       encoding = Jason.encode!(card) |> Diffo.Util.summarise_dates()
 
       assert encoding ==
-               ~s({\"id\":\"#{card.id}",\"href\":\"resourceInventoryManagement/v4/resource/#{card.id}",\"category\":\"Network Resource\",\"description\":\"A Card Resource Instance\",\"resourceSpecification\":{\"id\":\"cd29956f-6c68-44cc-bf54-705eb8d2f754\",\"href\":\"resourceCatalogManagement/v4/resourceSpecification/cd29956f-6c68-44cc-bf54-705eb8d2f754\",\"name\":\"card\",\"version\":\"v1.0.0\"},\"lifecycleState\":\"operating\",\"resourceRelationship\":[{\"type\":\"assignedTo\",\"resource\":{\"id\":\"#{assignee.id}\",\"href\":\"resourceInventoryManagement/v4/resource/#{assignee.id}\"},\"resourceRelationshipCharacteristic\":[{\"name\":\"port\",\"value\":1}]}]})
+               ~s({\"id\":\"#{card.id}",\"href\":\"resourceInventoryManagement/v4/resource/#{card.id}",\"category\":\"Network Resource\",\"description\":\"A Card Resource Instance\",\"resourceSpecification\":{\"id\":\"cd29956f-6c68-44cc-bf54-705eb8d2f754\",\"href\":\"resourceCatalogManagement/v4/resourceSpecification/cd29956f-6c68-44cc-bf54-705eb8d2f754\",\"name\":\"card\",\"version\":\"v1.0.0\"},\"lifecycleState\":\"operating\",\"resourceRelationship\":[{\"type\":\"assignedTo\",\"resource\":{\"id\":\"#{assignee.id}\",\"href\":\"resourceInventoryManagement/v4/resource/#{assignee.id}\"},\"resourceRelationshipCharacteristic\":[{\"name\":\"port\",\"value\":1}]}],\"resourceCharacteristic\":[{\"name\":\"card\",\"value\":{\"family\":\"ISAM\",\"model\":\"EBLT48\",\"technology\":\"adsl2Plus\"}},{\"name\":\"ports\",\"value\":{\"first\":1,\"last\":48,\"type\":\"ADSL2+\",\"algorithm\":\"lowest\"}}]})
     end
 
     test "auto assign two ports to same resource" do
@@ -188,7 +188,7 @@ defmodule Diffo.Provider.Extension.AssignerTest do
       encoding = Jason.encode!(card) |> Diffo.Util.summarise_dates()
 
       assert encoding ==
-               ~s({\"id\":\"#{card.id}",\"href\":\"resourceInventoryManagement/v4/resource/#{card.id}",\"category\":\"Network Resource\",\"description\":\"A Card Resource Instance\",\"resourceSpecification\":{\"id\":\"cd29956f-6c68-44cc-bf54-705eb8d2f754\",\"href\":\"resourceCatalogManagement/v4/resourceSpecification/cd29956f-6c68-44cc-bf54-705eb8d2f754\",\"name\":\"card\",\"version\":\"v1.0.0\"},\"lifecycleState\":\"operating\",\"resourceRelationship\":[{\"type\":\"assignedTo\",\"resource\":{\"id\":\"#{assignee.id}\",\"href\":\"resourceInventoryManagement/v4/resource/#{assignee.id}\"},\"resourceRelationshipCharacteristic\":[{\"name\":\"port\",\"value\":1}]},{\"type\":\"assignedTo\",\"resource\":{\"id\":\"#{assignee.id}\",\"href\":\"resourceInventoryManagement/v4/resource/#{assignee.id}\"},\"resourceRelationshipCharacteristic\":[{\"name\":\"port\",\"value\":2}]}]})
+               ~s({\"id\":\"#{card.id}",\"href\":\"resourceInventoryManagement/v4/resource/#{card.id}",\"category\":\"Network Resource\",\"description\":\"A Card Resource Instance\",\"resourceSpecification\":{\"id\":\"cd29956f-6c68-44cc-bf54-705eb8d2f754\",\"href\":\"resourceCatalogManagement/v4/resourceSpecification/cd29956f-6c68-44cc-bf54-705eb8d2f754\",\"name\":\"card\",\"version\":\"v1.0.0\"},\"lifecycleState\":\"operating\",\"resourceRelationship\":[{\"type\":\"assignedTo\",\"resource\":{\"id\":\"#{assignee.id}\",\"href\":\"resourceInventoryManagement/v4/resource/#{assignee.id}\"},\"resourceRelationshipCharacteristic\":[{\"name\":\"port\",\"value\":1}]},{\"type\":\"assignedTo\",\"resource\":{\"id\":\"#{assignee.id}\",\"href\":\"resourceInventoryManagement/v4/resource/#{assignee.id}\"},\"resourceRelationshipCharacteristic\":[{\"name\":\"port\",\"value\":2}]}],\"resourceCharacteristic\":[{\"name\":\"card\",\"value\":{\"family\":\"ISAM\",\"model\":\"EBLT48\",\"technology\":\"adsl2Plus\"}},{\"name\":\"ports\",\"value\":{\"first\":1,\"last\":48,\"type\":\"ADSL2+\",\"algorithm\":\"lowest\"}}]})
     end
 
     test "specific assignment rejects duplicate request" do
@@ -219,7 +219,7 @@ defmodule Diffo.Provider.Extension.AssignerTest do
       encoding = Jason.encode!(card) |> Diffo.Util.summarise_dates()
 
       assert encoding ==
-               ~s({\"id\":\"#{card.id}",\"href\":\"resourceInventoryManagement/v4/resource/#{card.id}",\"category\":\"Network Resource\",\"description\":\"A Card Resource Instance\",\"resourceSpecification\":{\"id\":\"cd29956f-6c68-44cc-bf54-705eb8d2f754\",\"href\":\"resourceCatalogManagement/v4/resourceSpecification/cd29956f-6c68-44cc-bf54-705eb8d2f754\",\"name\":\"card\",\"version\":\"v1.0.0\"},\"lifecycleState\":\"operating\",\"resourceRelationship\":[{\"type\":\"assignedTo\",\"resource\":{\"id\":\"#{assignee.id}\",\"href\":\"resourceInventoryManagement/v4/resource/#{assignee.id}\"},\"resourceRelationshipCharacteristic\":[{\"name\":\"port\",\"value\":5}]}]})
+               ~s({\"id\":\"#{card.id}",\"href\":\"resourceInventoryManagement/v4/resource/#{card.id}",\"category\":\"Network Resource\",\"description\":\"A Card Resource Instance\",\"resourceSpecification\":{\"id\":\"cd29956f-6c68-44cc-bf54-705eb8d2f754\",\"href\":\"resourceCatalogManagement/v4/resourceSpecification/cd29956f-6c68-44cc-bf54-705eb8d2f754\",\"name\":\"card\",\"version\":\"v1.0.0\"},\"lifecycleState\":\"operating\",\"resourceRelationship\":[{\"type\":\"assignedTo\",\"resource\":{\"id\":\"#{assignee.id}\",\"href\":\"resourceInventoryManagement/v4/resource/#{assignee.id}\"},\"resourceRelationshipCharacteristic\":[{\"name\":\"port\",\"value\":5}]}],\"resourceCharacteristic\":[{\"name\":\"card\",\"value\":{\"family\":\"ISAM\",\"model\":\"EBLT48\",\"technology\":\"adsl2Plus\"}},{\"name\":\"ports\",\"value\":{\"first\":1,\"last\":48,\"type\":\"ADSL2+\",\"algorithm\":\"lowest\"}}]})
     end
 
     test "unassign an auto-assigned port from a resource" do
@@ -258,7 +258,7 @@ defmodule Diffo.Provider.Extension.AssignerTest do
       encoding = Jason.encode!(card) |> Diffo.Util.summarise_dates()
 
       assert encoding ==
-               ~s({\"id\":\"#{card.id}",\"href\":\"resourceInventoryManagement/v4/resource/#{card.id}",\"category\":\"Network Resource\",\"description\":\"A Card Resource Instance\",\"resourceSpecification\":{\"id\":\"cd29956f-6c68-44cc-bf54-705eb8d2f754\",\"href\":\"resourceCatalogManagement/v4/resourceSpecification/cd29956f-6c68-44cc-bf54-705eb8d2f754\",\"name\":\"card\",\"version\":\"v1.0.0\"},\"lifecycleState\":\"operating\"})
+               ~s({\"id\":\"#{card.id}",\"href\":\"resourceInventoryManagement/v4/resource/#{card.id}",\"category\":\"Network Resource\",\"description\":\"A Card Resource Instance\",\"resourceSpecification\":{\"id\":\"cd29956f-6c68-44cc-bf54-705eb8d2f754\",\"href\":\"resourceCatalogManagement/v4/resourceSpecification/cd29956f-6c68-44cc-bf54-705eb8d2f754\",\"name\":\"card\",\"version\":\"v1.0.0\"},\"lifecycleState\":\"operating\",\"resourceCharacteristic\":[{\"name\":\"card\",\"value\":{\"family\":\"ISAM\",\"model\":\"EBLT48\",\"technology\":\"adsl2Plus\"}},{\"name\":\"ports\",\"value\":{\"first\":1,\"last\":48,\"type\":\"ADSL2+\",\"algorithm\":\"lowest\"}}]})
     end
 
     test "auto assign port to resource in :installing state (#168)" do
diff --git a/test/support/resource/characteristic/card_characteristic.ex b/test/support/resource/characteristic/card_characteristic.ex
index ad9ea36..bb8ef8a 100644
--- a/test/support/resource/characteristic/card_characteristic.ex
+++ b/test/support/resource/characteristic/card_characteristic.ex
@@ -13,20 +13,6 @@ defmodule Diffo.Test.Characteristic.CardCharacteristic do
     plural_name :card_values
   end
 
-  actions do
-    create :create do
-      accept [:name, :family, :model, :technology]
-      argument :instance_id, :uuid
-      argument :feature_id, :uuid
-      change manage_relationship(:instance_id, :instance, type: :append)
-      change manage_relationship(:feature_id, :feature, type: :append)
-    end
-
-    update :update do
-      accept [:family, :model, :technology]
-    end
-  end
-
   attributes do
     attribute :family, :atom, public?: true, description: "the card family name"
     attribute :model, :string, public?: true, description: "the card model name"
diff --git a/test/support/resource/characteristic/deployment_class.ex b/test/support/resource/characteristic/deployment_class.ex
index 59f7b6b..7610b5b 100644
--- a/test/support/resource/characteristic/deployment_class.ex
+++ b/test/support/resource/characteristic/deployment_class.ex
@@ -13,20 +13,6 @@ defmodule Diffo.Test.Characteristic.DeploymentClass do
     plural_name :deployment_class_values
   end
 
-  actions do
-    create :create do
-      accept [:name, :class, :mask]
-      argument :instance_id, :uuid
-      argument :feature_id, :uuid
-      change manage_relationship(:instance_id, :instance, type: :append)
-      change manage_relationship(:feature_id, :feature, type: :append)
-    end
-
-    update :update do
-      accept [:class, :mask]
-    end
-  end
-
   attributes do
     attribute :class, :string, public?: true, description: "the deployment class"
     attribute :mask, :string, public?: true, description: "the mask name"
diff --git a/test/support/resource/characteristic/shelf_characteristic.ex b/test/support/resource/characteristic/shelf_characteristic.ex
index 3cdfc47..6a3e3e5 100644
--- a/test/support/resource/characteristic/shelf_characteristic.ex
+++ b/test/support/resource/characteristic/shelf_characteristic.ex
@@ -13,20 +13,6 @@ defmodule Diffo.Test.Characteristic.ShelfCharacteristic do
     plural_name :shelf_values
   end
 
-  actions do
-    create :create do
-      accept [:name, :family, :model, :technology]
-      argument :instance_id, :uuid
-      argument :feature_id, :uuid
-      change manage_relationship(:instance_id, :instance, type: :append)
-      change manage_relationship(:feature_id, :feature, type: :append)
-    end
-
-    update :update do
-      accept [:family, :model, :technology]
-    end
-  end
-
   attributes do
     attribute :family, :atom, public?: true, description: "the shelf family name"
     attribute :model, :string, public?: true, description: "the shelf model name"
diff --git a/test/support/resource/instance/access_service.ex b/test/support/resource/instance/access_service.ex
index 42f702d..acee2c5 100644
--- a/test/support/resource/instance/access_service.ex
+++ b/test/support/resource/instance/access_service.ex
@@ -39,20 +39,6 @@ defmodule Diffo.Test.Instance.AccessService do
     end
   end
 
-  calculations do
-    calculate :assigner_name, {:array, :string},
-      {Diffo.Provider.Calculations.FieldViaAssignedRelationship, [via: [:primary], field: :name]}
-
-    calculate :assigner_names, {:array, :string},
-      {Diffo.Provider.Calculations.FieldViaAssignedRelationship, [field: :name]}
-
-    calculate :assigned_port, {:array, :integer},
-      {Diffo.Provider.Calculations.FieldFromAssignment, [alias: :primary, field: :value]}
-
-    calculate :all_assignment_values, {:array, :integer},
-      {Diffo.Provider.Calculations.FieldFromAssignment, [field: :value]}
-  end
-
   actions do
     create :build do
       accept [:id, :name, :type]
@@ -61,4 +47,23 @@ defmodule Diffo.Test.Instance.AccessService do
       upsert? false
     end
   end
+
+  calculations do
+    calculate :assigner_name,
+              {:array, :string},
+              {Diffo.Provider.Calculations.FieldViaAssignedRelationship,
+               [via: [:primary], field: :name]}
+
+    calculate :assigner_names,
+              {:array, :string},
+              {Diffo.Provider.Calculations.FieldViaAssignedRelationship, [field: :name]}
+
+    calculate :assigned_port,
+              {:array, :integer},
+              {Diffo.Provider.Calculations.FieldFromAssignment, [alias: :primary, field: :value]}
+
+    calculate :all_assignment_values,
+              {:array, :integer},
+              {Diffo.Provider.Calculations.FieldFromAssignment, [field: :value]}
+  end
 end
diff --git a/test/support/resource/instance/card_instance.ex b/test/support/resource/instance/card_instance.ex
index b0e27c3..eb01721 100644
--- a/test/support/resource/instance/card_instance.ex
+++ b/test/support/resource/instance/card_instance.ex
@@ -9,11 +9,8 @@ defmodule Diffo.Test.Instance.CardInstance do
   Card - Card Resource Instance
   """
   alias Diffo.Provider.BaseInstance
-  alias Diffo.Provider.Instance.Relationship
-  alias Diffo.Provider.Extension.Characteristic
-  alias Diffo.Provider.Extension.Pool
-  alias Diffo.Provider.Assigner
   alias Diffo.Provider.Assignment
+  alias Diffo.Provider.Changes
   alias Diffo.Test.Servo
   alias Diffo.Test.Characteristic.CardCharacteristic
 
@@ -70,36 +67,19 @@ defmodule Diffo.Test.Instance.CardInstance do
     update :define do
       description "defines the card"
       argument :characteristic_value_updates, {:array, :term}
-
-      change after_action(fn changeset, result, _context ->
-               with {:ok, result} <-
-                      Characteristic.update_all(result, changeset, characteristics()),
-                    {:ok, result} <- Pool.update_pools(result, changeset, pools()),
-                    {:ok, result} <- Servo.get_card_by_id(result.id),
-                    do: {:ok, result}
-             end)
+      change Changes.Define
     end
 
     update :relate do
       description "relates the card with other instances"
       argument :relationships, {:array, :struct}
-
-      change after_action(fn changeset, result, _context ->
-               with {:ok, result} <- Relationship.relate_instance(result, changeset),
-                    {:ok, result} <- Servo.get_card_by_id(result.id),
-                    do: {:ok, result}
-             end)
+      change Changes.Relate
     end
 
     update :assign_port do
       description "relates the card with an instance by assigning a port"
       argument :assignment, :struct, constraints: [instance_of: Assignment]
-
-      change after_action(fn changeset, result, _context ->
-               with {:ok, result} <- Assigner.assign(result, changeset, :ports),
-                    {:ok, result} <- Servo.get_card_by_id(result.id),
-                    do: {:ok, result}
-             end)
+      change {Changes.Assign, pool: :ports}
     end
   end
 end
diff --git a/test/support/resource/instance/shelf_instance.ex b/test/support/resource/instance/shelf_instance.ex
index fb8f2ee..4c2af1d 100644
--- a/test/support/resource/instance/shelf_instance.ex
+++ b/test/support/resource/instance/shelf_instance.ex
@@ -10,11 +10,8 @@ defmodule Diffo.Test.Instance.ShelfInstance do
   """
 
   alias Diffo.Provider.BaseInstance
-  alias Diffo.Provider.Instance.Relationship
-  alias Diffo.Provider.Extension.Characteristic
-  alias Diffo.Provider.Extension.Pool
-  alias Diffo.Provider.Assigner
   alias Diffo.Provider.Assignment
+  alias Diffo.Provider.Changes
   alias Diffo.Test.Servo
   alias Diffo.Test.Characteristic.ShelfCharacteristic
   alias Diffo.Test.Characteristic.DeploymentClass
@@ -84,15 +81,6 @@ defmodule Diffo.Test.Instance.ShelfInstance do
     end
   end
 
-  calculations do
-    calculate :linked_target_name, {:array, :string},
-      {Diffo.Provider.Calculations.FieldViaRelationship, [alias: :link, field: :name]}
-
-    calculate :assigned_linked_name, {:array, :string},
-      {Diffo.Provider.Calculations.FieldViaRelationship,
-       [type: :assignedTo, alias: :link, field: :name]}
-  end
-
   actions do
     create :build do
       description "creates a new Shelf resource instance for build"
@@ -109,36 +97,30 @@ defmodule Diffo.Test.Instance.ShelfInstance do
     update :define do
       description "defines the shelf"
       argument :characteristic_value_updates, {:array, :term}
-
-      change after_action(fn changeset, result, _context ->
-               with {:ok, result} <-
-                      Characteristic.update_all(result, changeset, characteristics()),
-                    {:ok, result} <- Pool.update_pools(result, changeset, pools()),
-                    {:ok, result} <- Servo.get_shelf_by_id(result.id),
-                    do: {:ok, result}
-             end)
+      change Changes.Define
     end
 
     update :relate do
       description "relates the shelf with cards"
       argument :relationships, {:array, :struct}
-
-      change after_action(fn changeset, result, _context ->
-               with {:ok, result} <- Relationship.relate_instance(result, changeset),
-                    {:ok, result} <- Servo.get_shelf_by_id(result.id),
-                    do: {:ok, result}
-             end)
+      change Changes.Relate
     end
 
     update :assign_slot do
       description "relates the shelf with an instance by assigning a slot"
       argument :assignment, :struct, constraints: [instance_of: Assignment]
-
-      change after_action(fn changeset, result, _context ->
-               with {:ok, result} <- Assigner.assign(result, changeset, :slots),
-                    {:ok, result} <- Servo.get_shelf_by_id(result.id),
-                    do: {:ok, result}
-             end)
+      change {Changes.Assign, pool: :slots}
     end
   end
+
+  calculations do
+    calculate :linked_target_name,
+              {:array, :string},
+              {Diffo.Provider.Calculations.FieldViaRelationship, [alias: :link, field: :name]}
+
+    calculate :assigned_linked_name,
+              {:array, :string},
+              {Diffo.Provider.Calculations.FieldViaRelationship,
+               [type: :assignedTo, alias: :link, field: :name]}
+  end
 end
diff --git a/usage-rules.md b/usage-rules.md
index 218ae5c..287ddb0 100644
--- a/usage-rules.md
+++ b/usage-rules.md
@@ -124,7 +124,10 @@ end
 ```
 
 Each characteristic module uses `Diffo.Provider.BaseCharacteristic` as a fragment and declares
-its own attributes, a `:value` calculation, and create/update actions:
+its own attributes and a `:value` calculation. Default `:create` and `:update` actions
+covering all public attributes (with `:name` on `:create` only and `:instance_id` /
+`:feature_id` arguments wired to `manage_relationship`) are synthesised automatically —
+declare your own only when you need a narrower accept list:
 
 ```elixir
 defmodule MyApp.SpeedCharacteristic do
@@ -144,20 +147,6 @@ defmodule MyApp.SpeedCharacteristic do
     end
   end
 
-  actions do
-    create :create do
-      accept [:name, :downstream_mbps, :upstream_mbps]
-      argument :instance_id, :uuid
-      argument :feature_id, :uuid
-      change manage_relationship(:instance_id, :instance, type: :append)
-      change manage_relationship(:feature_id, :feature, type: :append)
-    end
-
-    update :update do
-      accept [:downstream_mbps, :upstream_mbps]
-    end
-  end
-
   preparations do
     prepare build(load: [:value])
   end
@@ -296,35 +285,31 @@ end
 - Each Instance module gets `pools/0` (list of declarations) and `pool/1` (lookup by name)
   generated at compile time.
 
-In the `:define` action, apply updates for both characteristics and pools:
+For the `:define`, `:relate`, and `:assign_*` action patterns use the bundled change
+modules. They wrap the standard after-action plumbing and reload via the resource's
+primary `:read` action — no per-domain reader is required:
 
 ```elixir
 update :define do
   argument :characteristic_value_updates, {:array, :term}
-
-  change after_action(fn changeset, result, _context ->
-    with {:ok, result} <- Characteristic.update_all(result, changeset, characteristics()),
-         {:ok, result} <- Pool.update_pools(result, changeset, pools()),
-         {:ok, result} <- MyDomain.get_by_id(result.id),
-         do: {:ok, result}
-  end)
+  change Diffo.Provider.Changes.Define
 end
-```
 
-In assignment actions, use `Assigner.assign/3` (thing is looked up from the pool declaration):
+update :relate do
+  argument :relationships, {:array, :struct}
+  change Diffo.Provider.Changes.Relate
+end
 
-```elixir
 update :assign_core do
   argument :assignment, :struct, constraints: [instance_of: Assignment]
-
-  change after_action(fn changeset, result, _context ->
-    with {:ok, result} <- Assigner.assign(result, changeset, :cores),
-         {:ok, result} <- MyDomain.get_by_id(result.id),
-         do: {:ok, result}
-  end)
+  change {Diffo.Provider.Changes.Assign, pool: :cores}
 end
 ```
 
+If you need to do more than the standard pattern, the underlying helpers
+(`Characteristic.update_all/3`, `Pool.update_pools/3`, `Relationship.relate_instance/2`,
+`Assigner.assign/3`) remain available for a hand-written `after_action`.
+
 ### `relationships do` — Instance only
 
 Declares which relationship roles this Instance kind may participate in as a **source** or