diff --git a/documentation/dsls/DSL-Diffo.Provider.Instance.Extension.md b/documentation/dsls/DSL-Diffo.Provider.Instance.Extension.md
index bf9d55b..6b5c7d3 100644
--- a/documentation/dsls/DSL-Diffo.Provider.Instance.Extension.md
+++ b/documentation/dsls/DSL-Diffo.Provider.Instance.Extension.md
@@ -5,15 +5,77 @@ This file was generated by Spark. Do not edit it by hand.
 
 DSL Extension customising an Instance.
 
-Provides compile-time declaration blocks for domain-specific Service and Resource kinds
-built on `Diffo.Provider.BaseInstance`. All declarations are introspectable via
-`Diffo.Provider.Instance.Extension.Info`.
+Provides two top-level sections:
+
+## structure
+
+Describes the static shape of the Instance kind — what it is, what values it carries,
+and what parties it relates to. All structure declarations are baked into the resource
+module at compile time via persisters and are introspectable at runtime via
+`Diffo.Provider.Instance.Info` or directly as generated functions on the resource module.
+
+- `specification do` — the TMF Specification (id, name, type, version, description, category).
+  The id is a stable UUID4 that is the same across all environments for this Instance kind.
+- `characteristics do` — typed value slots carried by instances of this kind, each backed
+  by an `Ash.TypedStruct`.
+- `features do` — optional capabilities of this kind, each with its own typed characteristic
+  payload and an enabled/disabled default.
+- `parties do` — the party roles that instances of this kind relate to, with multiplicity,
+  reference, and calculation options.
+
+## behaviour
+
+Declares which Ash actions should be wired for instance build lifecycle management.
+Currently supports `create` declarations; future sections will cover triggers and other
+lifecycle concerns.
+
+Declaring `create :name` in `behaviour do actions do` causes the `TransformBehaviour`
+transformer to inject `:specified_by`, `:features`, and `:characteristics` arguments onto
+the named Ash create action. These arguments carry the UUIDs of the TMF entities created
+by `build_before/1` and consumed by the Ash relationship management in the action.
 
 See the [DSL cheat sheet](DSL-Diffo.Provider.Instance.Extension.html) for the full DSL reference.
-See `Diffo.Provider.BaseInstance` for full usage documentation.
+See `Diffo.Provider.BaseInstance` for full usage documentation including generated functions.
+
+
+## structure
+Defines the structural shape of the Instance — its specification, characteristics, features, and parties
+
+### Nested DSLs
+ * [specification](#structure-specification)
+ * [characteristics](#structure-characteristics)
+   * characteristic
+ * [features](#structure-features)
+   * feature
+     * characteristic
+ * [parties](#structure-parties)
+   * party
+   * parties
+
+
+### Examples
+```
+structure do
+  specification do
+    id "da9b207a-26c3-451d-8abd-0640c6349979"
+    name "DSL Access Service"
+    type :serviceSpecification
+  end
+
+  characteristics do
+    characteristic :circuit, Diffo.Access.Circuit
+  end
+
+  parties do
+    party :provider, MyApp.Provider
+  end
+end
+
+```
+
 
 
-## specification
+### structure.specification
 Defines the Instance Specification
 
 
@@ -38,23 +100,68 @@ end
 
 | Name | Type | Default | Docs |
 |------|------|---------|------|
-| [`id`](#specification-id){: #specification-id .spark-required} | `String.t` |  | The id of the specification, a uuid4 the same in all environments, unique for name and major_version. |
-| [`name`](#specification-name){: #specification-name .spark-required} | `String.t` |  | The name of the specification, unique to a service but common for all versions. |
-| [`type`](#specification-type){: #specification-type } | `atom` | `:serviceSpecification` | The type of the specification. |
-| [`major_version`](#specification-major_version){: #specification-major_version } | `integer` | `1` | The major_version of the specification. |
-| [`description`](#specification-description){: #specification-description } | `String.t` |  | A generic description of the specified service or resource. |
-| [`category`](#specification-category){: #specification-category } | `String.t` |  | The category the specified service or resource belongs to. |
+| [`id`](#structure-specification-id){: #structure-specification-id .spark-required} | `String.t` |  | The id of the specification, a uuid4 the same in all environments, unique for name and major_version. |
+| [`name`](#structure-specification-name){: #structure-specification-name .spark-required} | `String.t` |  | The name of the specification, unique to a service but common for all versions. |
+| [`type`](#structure-specification-type){: #structure-specification-type } | `atom` | `:serviceSpecification` | The type of the specification. |
+| [`major_version`](#structure-specification-major_version){: #structure-specification-major_version } | `integer` | `1` | The major_version of the specification. |
+| [`description`](#structure-specification-description){: #structure-specification-description } | `String.t` |  | A generic description of the specified service or resource. |
+| [`category`](#structure-specification-category){: #structure-specification-category } | `String.t` |  | The category the specified service or resource belongs to. |
+
+
+
+
+### structure.characteristics
+List of Instance Characteristics
+
+### Nested DSLs
+ * [characteristic](#structure-characteristics-characteristic)
+
+
+### Examples
+```
+characteristics do
+  characteristic :dslam, Diffo.Access.Dslam
+  characteristic :aggregate_interface, Diffo.Access.AggregateInterface
+  characteristic :circuit, Diffo.Access.Circuit
+  characteristic :line, Diffo.Access.Line
+end
+
+```
+
+
+
+
+### structure.characteristics.characteristic
+```elixir
+characteristic name, value_type
+```
+
+
+Adds a Characteristic
+
+
+
+
+
+### Arguments
+
+| Name | Type | Default | Docs |
+|------|------|---------|------|
+| [`name`](#structure-characteristics-characteristic-name){: #structure-characteristics-characteristic-name .spark-required} | `atom` |  | The name of the characteristic, an atom |
+| [`value_type`](#structure-characteristics-characteristic-value_type){: #structure-characteristics-characteristic-value_type } | `any` |  | The type of the characteristic's value. An atom module name such as an Ash.TypedStruct for a scalar value, or `{:array, module}` for an array of values of that type. |
 
 
 
 
 
 
-## features
+
+
+### structure.features
 Configuration for Instance Features
 
 ### Nested DSLs
- * [feature](#features-feature)
+ * [feature](#structure-features-feature)
    * characteristic
 
 
@@ -74,7 +181,7 @@ end
 
 
 
-### features.feature
+### structure.features.feature
 ```elixir
 feature name
 ```
@@ -83,7 +190,7 @@ feature name
 Adds a Feature
 
 ### Nested DSLs
- * [characteristic](#features-feature-characteristic)
+ * [characteristic](#structure-features-feature-characteristic)
 
 
 
@@ -92,15 +199,15 @@ Adds a Feature
 
 | Name | Type | Default | Docs |
 |------|------|---------|------|
-| [`name`](#features-feature-name){: #features-feature-name .spark-required} | `atom` |  | The name of the feature, an atom |
+| [`name`](#structure-features-feature-name){: #structure-features-feature-name .spark-required} | `atom` |  | The name of the feature, an atom |
 ### Options
 
 | Name | Type | Default | Docs |
 |------|------|---------|------|
-| [`is_enabled?`](#features-feature-is_enabled?){: #features-feature-is_enabled? } | `boolean` |  | Whether the feature is enabled by default, defaults true |
+| [`is_enabled?`](#structure-features-feature-is_enabled?){: #structure-features-feature-is_enabled? } | `boolean` |  | Whether the feature is enabled by default, defaults true |
 
 
-### features.feature.characteristic
+### structure.features.feature.characteristic
 ```elixir
 characteristic name, value_type
 ```
@@ -116,9 +223,8 @@ Adds a Characteristic
 
 | Name | Type | Default | Docs |
 |------|------|---------|------|
-| [`name`](#features-feature-characteristic-name){: #features-feature-characteristic-name .spark-required} | `atom` |  | The name of the characteristic, an atom |
-| [`value_type`](#features-feature-characteristic-value_type){: #features-feature-characteristic-value_type } | `any` |  | The type of the characteristic's value. An atom module name such as an Ash.TypedStruct for a scalar value,   or `{:array, module}` for an array of values of that type. |
-
+| [`name`](#structure-features-feature-characteristic-name){: #structure-features-feature-characteristic-name .spark-required} | `atom` |  | The name of the characteristic, an atom |
+| [`value_type`](#structure-features-feature-characteristic-value_type){: #structure-features-feature-characteristic-value_type } | `any` |  | The type of the characteristic's value. An atom module name such as an Ash.TypedStruct for a scalar value, or `{:array, module}` for an array of values of that type. |
 
 
 
@@ -131,21 +237,20 @@ Adds a Characteristic
 
 
 
-
-## characteristics
-List of Instance Characteristics
+### structure.parties
+List of Instance Party roles
 
 ### Nested DSLs
- * [characteristic](#characteristics-characteristic)
+ * [party](#structure-parties-party)
+ * [parties](#structure-parties-parties)
 
 
 ### Examples
 ```
-characteristics do
-  characteristic :dslam, Diffo.Access.Dslam
-  characteristic :aggregate_interface, Diffo.Access.AggregateInterface
-  characteristic :circuit, Diffo.Access.Circuit
-  characteristic :line, Diffo.Access.Line
+parties do
+  party :provider, MyApp.Provider, calculate: :provider_calculation
+  parties :technician, MyApp.Technician, constraints: [min: 1, max: 3]
+  party :owner, MyApp.InfrastructureCo, reference: true
 end
 
 ```
@@ -153,13 +258,13 @@ end
 
 
 
-### characteristics.characteristic
+### structure.parties.party
 ```elixir
-characteristic name, value_type
+party role, party_type
 ```
 
 
-Adds a Characteristic
+Declares a singular party role on this Instance
 
 
 
@@ -169,46 +274,111 @@ Adds a Characteristic
 
 | Name | Type | Default | Docs |
 |------|------|---------|------|
-| [`name`](#characteristics-characteristic-name){: #characteristics-characteristic-name .spark-required} | `atom` |  | The name of the characteristic, an atom |
-| [`value_type`](#characteristics-characteristic-value_type){: #characteristics-characteristic-value_type } | `any` |  | The type of the characteristic's value. An atom module name such as an Ash.TypedStruct for a scalar value,   or `{:array, module}` for an array of values of that type. |
+| [`role`](#structure-parties-party-role){: #structure-parties-party-role .spark-required} | `atom` |  | The role name, an atom |
+| [`party_type`](#structure-parties-party-party_type){: #structure-parties-party-party_type } | `any` |  | The module of the Party kind. An atom module name such as a BaseParty-derived resource. |
+### Options
 
+| Name | Type | Default | Docs |
+|------|------|---------|------|
+| [`reference`](#structure-parties-party-reference){: #structure-parties-party-reference } | `boolean` | `false` | If true, no direct PartyRef edge is created; the party is reachable by graph traversal. |
+| [`calculate`](#structure-parties-party-calculate){: #structure-parties-party-calculate } | `atom` |  | Name of an Ash calculation on this resource that produces the party at build time. |
 
 
 
 
 
+### Introspection
 
+Target: `Diffo.Provider.Instance.Extension.PartyDeclaration`
 
+### structure.parties.parties
+```elixir
+parties role, party_type
+```
+
+
+Declares a plural party role on this Instance
+
+
+
+
+
+### Arguments
+
+| Name | Type | Default | Docs |
+|------|------|---------|------|
+| [`role`](#structure-parties-parties-role){: #structure-parties-parties-role .spark-required} | `atom` |  | The role name, an atom |
+| [`party_type`](#structure-parties-parties-party_type){: #structure-parties-parties-party_type } | `any` |  | The module of the Party kind. An atom module name such as a BaseParty-derived resource. |
+### Options
+
+| Name | Type | Default | Docs |
+|------|------|---------|------|
+| [`reference`](#structure-parties-parties-reference){: #structure-parties-parties-reference } | `boolean` | `false` | If true, no direct PartyRef edge is created; the party is reachable by graph traversal. |
+| [`calculate`](#structure-parties-parties-calculate){: #structure-parties-parties-calculate } | `atom` |  | Name of an Ash calculation on this resource that produces the party at build time. |
+| [`constraints`](#structure-parties-parties-constraints){: #structure-parties-parties-constraints } | `keyword` |  | Multiplicity constraints on the number of parties in this role, e.g. [min: 1, max: 3] |
+
+
+
+
+
+### Introspection
+
+Target: `Diffo.Provider.Instance.Extension.PartyDeclaration`
 
 
-## parties
-List of Instance Party roles
+
+
+
+
+## behaviour
+Defines the behavioural wiring for the Instance — actions, and in future triggers and tasks
 
 ### Nested DSLs
- * [party](#parties-party)
- * [parties](#parties-parties)
+ * [actions](#behaviour-actions)
+   * create
+   * update
 
 
 ### Examples
 ```
-parties do
-  party :provider, MyApp.Provider, calculate: :provider_calculation
-  parties :technician, MyApp.Technician, constraints: [min: 1, max: 3]
-  party :owner, MyApp.InfrastructureCo, reference: true
+behaviour do
+  actions do
+    create :build
+    update :define
+  end
 end
 
 ```
 
 
 
+### behaviour.actions
+Declares which actions to wire for instance behaviour
+
+### Nested DSLs
+ * [create](#behaviour-actions-create)
+ * [update](#behaviour-actions-update)
+
+
+### Examples
+```
+actions do
+  create :build
+  update :define
+end
+
+```
+
 
-### parties.party
+
+
+### behaviour.actions.create
 ```elixir
-party role, party_type
+create name
 ```
 
 
-Declares a singular party role on this Instance
+Marks a create action for instance build wiring, injecting :specified_by, :features, and :characteristics arguments
 
 
 
@@ -218,30 +388,21 @@ Declares a singular party role on this Instance
 
 | Name | Type | Default | Docs |
 |------|------|---------|------|
-| [`role`](#parties-party-role){: #parties-party-role .spark-required} | `atom` |  | The role name, an atom |
-| [`party_type`](#parties-party-party_type){: #parties-party-party_type } | `any` |  | The module of the Party kind. An atom module name such as a BaseParty-derived resource. |
-### Options
+| [`name`](#behaviour-actions-create-name){: #behaviour-actions-create-name .spark-required} | `atom` |  | The name of the create action to wire |
 
-| Name | Type | Default | Docs |
-|------|------|---------|------|
-| [`reference`](#parties-party-reference){: #parties-party-reference } | `boolean` | `false` | If true, no direct PartyRef edge is created; the party is reachable by graph traversal. |
-| [`calculate`](#parties-party-calculate){: #parties-party-calculate } | `atom` |  | Name of an Ash calculation on this resource that produces the party at build time. |
 
 
 
 
 
-### Introspection
-
-Target: `Diffo.Provider.Instance.Extension.PartyDeclaration`
 
-### parties.parties
+### behaviour.actions.update
 ```elixir
-parties role, party_type
+update name
 ```
 
 
-Declares a plural party role on this Instance
+Marks an update action for instance behaviour wiring
 
 
 
@@ -251,23 +412,15 @@ Declares a plural party role on this Instance
 
 | Name | Type | Default | Docs |
 |------|------|---------|------|
-| [`role`](#parties-parties-role){: #parties-parties-role .spark-required} | `atom` |  | The role name, an atom |
-| [`party_type`](#parties-parties-party_type){: #parties-parties-party_type } | `any` |  | The module of the Party kind. An atom module name such as a BaseParty-derived resource. |
-### Options
+| [`name`](#behaviour-actions-update-name){: #behaviour-actions-update-name .spark-required} | `atom` |  | The name of the update action to wire |
+
 
-| Name | Type | Default | Docs |
-|------|------|---------|------|
-| [`reference`](#parties-parties-reference){: #parties-parties-reference } | `boolean` | `false` | If true, no direct PartyRef edge is created; the party is reachable by graph traversal. |
-| [`calculate`](#parties-parties-calculate){: #parties-parties-calculate } | `atom` |  | Name of an Ash calculation on this resource that produces the party at build time. |
-| [`constraints`](#parties-parties-constraints){: #parties-parties-constraints } | `keyword` |  | Multiplicity constraints on the number of parties in this role, e.g. [min: 1, max: 3] |
 
 
 
 
 
-### Introspection
 
-Target: `Diffo.Provider.Instance.Extension.PartyDeclaration`
 
 
 
diff --git a/documentation/how_to/use_diffo_provider_extension.livemd b/documentation/how_to/use_diffo_provider_extension.livemd
index 974a475..587fbfd 100644
--- a/documentation/how_to/use_diffo_provider_extension.livemd
+++ b/documentation/how_to/use_diffo_provider_extension.livemd
@@ -144,7 +144,12 @@ end
 
 Diffo also has an inbuilt Spark DSL extension [Diffo.Provider.Instance.Extension](https://hexdocs.pm/diffo/Diffo.Provider.Instance.Extension.html) which provides DSL and functions for use in building and operating domain specific services and resources.
 
-Currently it has DSL to allow you to declare specification, features, characteristics, and party roles. It can be used for services or resources.
+The extension has two top-level sections:
+
+**`structure do`** — describes the static shape of the Instance kind: its TMF Specification, Characteristics, Features, and Party roles. All declarations are baked into the module at compile time and introspectable at runtime via generated functions (`specification/0`, `characteristics/0`, `features/0`, `parties/0`) and `Diffo.Provider.Instance.Info`.
+
+**`behaviour do`** — declares which Ash actions should be wired for instance lifecycle management. Declaring `create :name` injects `:specified_by`, `:features`, and `:characteristics` arguments onto that action, and the `BuildBefore`/`BuildAfter` changes registered on `BaseInstance` automatically handle specification upsert, feature and characteristic creation, party validation, and graph relationship wiring for every create action. You write the action body for your domain-specific accepts and arguments; the structural wiring is handled for you.
+
 Feature and Instance Characteristics can have payloads defined by [Ash.TypedStruct](https://hexdocs.pm/ash/Ash.TypedStruct.html). TypedStruct are DSL specified types which are effectively lightweight embedded resources. We've extended both [AshJason](https://hexdocs.pm/ash_jason/) and [AshOutstanding](https://hexdocs.pm/ash_outstanding/) to support Ash.TypedStruct.
 
 For partial resource allocation and assignment we've created Diffo.Provider.Assigner. It is used by the host resource, which declares a characteristic with an Diffo.Provider.AssignableValue TypedStruct. Allocation is managed within the Provider domain using this characteristic. Assignment to Services or Resources is via 'reverse' type: "assignedTo" relationships enriched by relationship characteristics.
@@ -172,7 +177,6 @@ defmodule Diffo.Compute.Cluster do
   alias Diffo.Provider.BaseInstance
   alias Diffo.Provider.Instance.Relationship
   alias Diffo.Provider.Instance.Characteristic
-  alias Diffo.Provider.Instance.ActionHelper
   alias Diffo.Compute
   alias Diffo.Compute.ClusterValue
   alias Diffo.Compute.Tenant
@@ -187,42 +191,40 @@ defmodule Diffo.Compute.Cluster do
     plural_name :Clusters
   end
 
-  specification do
-    id "4bcfc4c9-e776-4878-a658-e8d81857bed7"
-    name "cluster"
-    type :resourceSpecification
-    description "A Cluster Resource Instance"
-    category "Network Resource"
-  end
+  structure do
+    specification do
+      id "4bcfc4c9-e776-4878-a658-e8d81857bed7"
+      name "cluster"
+      type :resourceSpecification
+      description "A Cluster Resource Instance"
+      category "Network Resource"
+    end
+
+    characteristics do
+      characteristic :cluster, ClusterValue
+    end
 
-  characteristics do
-    characteristic :cluster, ClusterValue
+    parties do
+      party :operator, Tenant
+      party :manager, Engineer
+    end
   end
 
-  parties do
-    party :operator, Tenant
-    party :manager, Engineer
+  behaviour do
+    actions do
+      create :build
+    end
   end
 
   actions do
     create :build do
       description "creates a new Cluster resource instance for build"
       accept [:id, :name, :type, :which]
-      argument :specified_by, :uuid, public?: false
       argument :relationships, {:array, :struct}
-      argument :features, {:array, :uuid}, public?: false
-      argument :characteristics, {:array, :uuid}, public?: false
       argument :places, {:array, :struct}
       argument :parties, {:array, :struct}
 
       change set_attribute(:type, :resource)
-
-      change before_action(fn changeset, _context -> ActionHelper.build_before(changeset) end)
-
-      change after_action(fn changeset, result, _context ->
-          ActionHelper.build_after(changeset, result, Compute, :get_cluster_by_id)
-        end)
-
       change load [:href]
       upsert? false
     end
@@ -232,7 +234,7 @@ defmodule Diffo.Compute.Cluster do
       argument :characteristic_value_updates, {:array, :term}
 
       change after_action(fn changeset, result, _context ->
-               with {:ok, _result} <- Characteristic.update_values(result, changeset),
+               with {:ok, result} <- Characteristic.update_values(result, changeset),
                     {:ok, cluster} <- Compute.get_cluster_by_id(result.id),
                     do: {:ok, cluster}
              end)
@@ -305,7 +307,6 @@ defmodule Diffo.Compute.GPU do
   alias Diffo.Provider.BaseInstance
   alias Diffo.Provider.Instance.Relationship
   alias Diffo.Provider.Instance.Characteristic
-  alias Diffo.Provider.Instance.ActionHelper
   alias Diffo.Provider.Assigner
   alias Diffo.Provider.Assignment
   alias Diffo.Provider.AssignableValue
@@ -321,38 +322,36 @@ defmodule Diffo.Compute.GPU do
     plural_name :gpus
   end
 
-  specification do
-    id "ad50073f-17e0-45cb-b9b1-aa4296876156"
-    name "gpu"
-    type :resourceSpecification
-    description "A GPU Resource Instance"
-    category "Network Resource"
+  structure do
+    specification do
+      id "ad50073f-17e0-45cb-b9b1-aa4296876156"
+      name "gpu"
+      type :resourceSpecification
+      description "A GPU Resource Instance"
+      category "Network Resource"
+    end
+
+    characteristics do
+      characteristic :gpu, GPUValue
+      characteristic :cores, AssignableValue
+    end
   end
 
-  characteristics do
-    characteristic :gpu, GPUValue
-    characteristic :cores, AssignableValue
+  behaviour do
+    actions do
+      create :build
+    end
   end
 
   actions do
     create :build do
       description "creates a new GPU resource instance for build"
       accept [:id, :name, :type, :which]
-      argument :specified_by, :uuid, public?: false
       argument :relationships, {:array, :struct}
-      argument :features, {:array, :uuid}, public?: false
-      argument :characteristics, {:array, :uuid}, public?: false
       argument :places, {:array, :struct}
       argument :parties, {:array, :struct}
 
       change set_attribute(:type, :resource)
-
-      change before_action(fn changeset, _context -> ActionHelper.build_before(changeset) end)
-
-      change after_action(fn changeset, result, _context ->
-          ActionHelper.build_after(changeset, result, Compute, :get_gpu_by_id)
-        end)
-
       change load [:href]
       upsert? false
     end
@@ -685,7 +684,7 @@ What happens when I request a specific assignment from an instance to which the
 
 In this tutorial you've used Diffo's Provider Instance Extension to define a Compute domain with a composite Cluster resource comprised of assigned GPU cores, and the Provider Party Extension to define Tenant and Engineer party kinds that operate and manage those resources.
 
-The BaseParty fragment follows the same pattern as BaseInstance — domain-specific resources use it as a fragment and finish their actions with a domain-scoped reload to pick up extended fields.
+`BaseParty` follows the same pattern as `BaseInstance` — domain-specific party resources use it as a fragment and write their own `build` action for domain-specific attributes. No manual wiring is needed.
 
 A `BasePlace` extension for domain-specific Place kinds (such as a DataCentre with its own attributes) follows the same pattern and will be added in a future release.
 
diff --git a/lib/diffo/provider/components/base_instance.ex b/lib/diffo/provider/components/base_instance.ex
index 6fcb5cd..d927cb4 100644
--- a/lib/diffo/provider/components/base_instance.ex
+++ b/lib/diffo/provider/components/base_instance.ex
@@ -4,7 +4,7 @@
 
 defmodule Diffo.Provider.BaseInstance do
   @moduledoc """
-  Ash Resource Fragment which is a the point of extension for your TMF Service or Resource Instance
+  Ash Resource Fragment which is the point of extension for your TMF Service or Resource Instance.
 
   `BaseInstance` is the foundation for domain-specific Service and Resource kinds.
   Include it as a fragment on an `Ash.Resource` to get common Instance attributes,
@@ -12,19 +12,22 @@ defmodule Diffo.Provider.BaseInstance do
 
   ## Instance Extension DSL
 
-  The `Diffo.Provider.Instance.Extension` DSL provides compile-time declaration blocks
-  for describing the shape of a domain-specific Service or Resource.
+  The DSL has two top-level sections: `structure do` describes what the instance kind is;
+  `behaviour do` wires it to Ash actions.
 
-  `specification do` — declares the TMF Specification for this Instance kind.
+  ### structure
 
-  `features do` — declares the Features this Instance kind may have, each optionally
-  carrying a typed characteristic payload.
+  `specification do` — declares the TMF Specification for this Instance kind (id, name, type,
+  major_version, description, category).
 
-  `characteristics do` — declares the top-level Characteristics of this Instance kind,
-  each backed by an `Ash.TypedStruct`.
+  `characteristics do` — declares the top-level Characteristics of this Instance kind, each
+  backed by an `Ash.TypedStruct`.
+
+  `features do` — declares the Features this Instance kind may have, each optionally carrying
+  its own typed characteristic payload.
 
   `parties do` — declares the Party roles this Instance kind relates to. Role names are
-  domain-specific nouns describing what the party is to the instance. Two forms:
+  domain-specific nouns describing what the party means to the instance. Two forms:
 
       parties do
         party :provider, MyApp.Provider, calculate: :provider_calculation
@@ -33,12 +36,44 @@ defmodule Diffo.Provider.BaseInstance do
         party :owner, MyApp.InfrastructureCo, reference: true
       end
 
-  - `party` — singular (at most one party in this role)
-  - `parties` — plural (unbounded, or bounded with `constraints:`)
+  - `party` — singular (at most one party in this role per instance)
+  - `parties` — plural (unbounded, or bounded with `constraints: [min: n, max: m]`)
   - `reference: true` — no direct `PartyRef` edge; party is reachable by graph traversal
   - `calculate:` — names an Ash calculation on this resource that produces the party at build time
 
-  All declarations are introspectable via `Diffo.Provider.Instance.Extension.Info`.
+  All declarations are introspectable at runtime via `Diffo.Provider.Instance.Info` and at
+  compile time via `Diffo.Provider.Instance.Extension.Info`.
+
+  ### behaviour
+
+  `behaviour do actions do create :name end end` — marks a named create action for build
+  wiring. This injects `:specified_by`, `:features`, and `:characteristics` arguments onto
+  that action so Ash accepts the values that `build_before/1` sets automatically.
+
+  You still write the action body yourself for domain-specific accepts, arguments, and changes.
+  The build arguments are not public and do not need to appear in `accept`.
+
+  ## Generated functions
+
+  Every resource using `BaseInstance` with a `specification do` gets the following functions
+  generated at compile time:
+
+  - `specification/0` — the specification keyword list baked at compile time
+  - `characteristics/0` — list of `Characteristic` structs
+  - `features/0` — list of `Feature` structs
+  - `parties/0` — list of `PartyDeclaration` structs
+  - `characteristic/1` — returns the named `Characteristic` or `nil`
+  - `feature/1` — returns the named `Feature` or `nil`
+  - `feature_characteristic/2` — returns the named characteristic within a feature, or `nil`
+  - `party/1` — returns the `PartyDeclaration` for the given role, or `nil`
+  - `build_before/1` — called automatically before every create action; upserts the
+    specification and creates features, characteristics, and parties, setting their ids
+    as action arguments
+  - `build_after/2` — called automatically after every create action; relates the created
+    TMF entities to the new instance node
+
+  Resources without a `specification do id` get trivial passthroughs for `build_before/1`
+  and `build_after/2`.
 
   ## Usage
 
@@ -50,28 +85,50 @@ defmodule Diffo.Provider.BaseInstance do
           plural_name :clusters
         end
 
-        specification do
-          id "4bcfc4c9-e776-4878-a658-e8d81857bed7"
-          name "cluster"
-          type :resourceSpecification
+        structure do
+          specification do
+            id "4bcfc4c9-e776-4878-a658-e8d81857bed7"
+            name "cluster"
+            type :resourceSpecification
+          end
+
+          parties do
+            party :operator, MyApp.Organization
+            parties :installer, MyApp.Engineer
+          end
+        end
+
+        behaviour do
+          actions do
+            create :build
+          end
         end
 
-        parties do
-          party :operator, MyApp.Organization
-          parties :installer, MyApp.Engineer
+        actions do
+          create :build do
+            description "creates a new Cluster resource instance"
+            accept [:id, :name, :type, :which]
+            argument :relationships, {:array, :struct}
+            argument :parties, {:array, :struct}
+
+            change set_attribute(:type, :resource)
+            change load [:href]
+            upsert? false
+          end
         end
       end
 
-  ## Action pattern
+  ## Rolling your own actions
 
-  Domain-specific Instance resources should finish their `build` action with a reload via
-  their own domain's `get_xxx_by_id` to pick up extended fields:
+  The `behaviour do actions do create :name end end` declaration is optional. Omitting it
+  means the `:specified_by`, `:features`, and `:characteristics` arguments are not declared
+  on that action — but `build_before/1` and `build_after/2` are still called for every
+  create via the global `BuildBefore` and `BuildAfter` changes registered on `BaseInstance`.
 
-      create :build do
-        change after_action(fn changeset, result, _context ->
-          ActionHelper.build_after(changeset, result, MyApp.Domain, :get_cluster_by_id)
-        end)
-      end
+  If you have a create action that should NOT trigger the full build wiring (e.g. a
+  lightweight admin create), you can override `build_before/1` or `build_after/2` on your
+  resource, or use Ash's `skip_unknown_inputs` to absorb the injected arguments without
+  declaring them.
   """
   use Spark.Dsl.Fragment,
     of: Ash.Resource,
@@ -357,6 +414,11 @@ defmodule Diffo.Provider.BaseInstance do
     end
   end
 
+  changes do
+    change Diffo.Provider.Instance.Extension.Changes.BuildBefore, on: [:create]
+    change Diffo.Provider.Instance.Extension.Changes.BuildAfter, on: [:create]
+  end
+
   actions do
     defaults [:destroy]
 
diff --git a/lib/diffo/provider/components/entity_ref.ex b/lib/diffo/provider/components/entity_ref.ex
index 532b3c9..8d09ff3 100644
--- a/lib/diffo/provider/components/entity_ref.ex
+++ b/lib/diffo/provider/components/entity_ref.ex
@@ -4,7 +4,7 @@
 
 defmodule Diffo.Provider.EntityRef do
   @moduledoc """
-  EntityRef - Ash Resource for a TMF Entity Reference
+  Ash Resource for a TMF Entity Reference
   """
   use Ash.Resource,
     otp_app: :diffo,
diff --git a/lib/diffo/provider/components/instance/extension.ex b/lib/diffo/provider/components/instance/extension.ex
index 3956787..222acc1 100644
--- a/lib/diffo/provider/components/instance/extension.ex
+++ b/lib/diffo/provider/components/instance/extension.ex
@@ -6,13 +6,41 @@ defmodule Diffo.Provider.Instance.Extension do
   @moduledoc """
   DSL Extension customising an Instance.
 
-  Provides compile-time declaration blocks for domain-specific Service and Resource kinds
-  built on `Diffo.Provider.BaseInstance`. All declarations are introspectable via
-  `Diffo.Provider.Instance.Extension.Info`.
+  Provides two top-level sections:
+
+  ## structure
+
+  Describes the static shape of the Instance kind — what it is, what values it carries,
+  and what parties it relates to. All structure declarations are baked into the resource
+  module at compile time via persisters and are introspectable at runtime via
+  `Diffo.Provider.Instance.Info` or directly as generated functions on the resource module.
+
+  - `specification do` — the TMF Specification (id, name, type, version, description, category).
+    The id is a stable UUID4 that is the same across all environments for this Instance kind.
+  - `characteristics do` — typed value slots carried by instances of this kind, each backed
+    by an `Ash.TypedStruct`.
+  - `features do` — optional capabilities of this kind, each with its own typed characteristic
+    payload and an enabled/disabled default.
+  - `parties do` — the party roles that instances of this kind relate to, with multiplicity,
+    reference, and calculation options.
+
+  ## behaviour
+
+  Declares which Ash actions should be wired for instance build lifecycle management.
+  Currently supports `create` declarations; future sections will cover triggers and other
+  lifecycle concerns.
+
+  Declaring `create :name` in `behaviour do actions do` causes the `TransformBehaviour`
+  transformer to inject `:specified_by`, `:features`, and `:characteristics` arguments onto
+  the named Ash create action. These arguments carry the UUIDs of the TMF entities created
+  by `build_before/1` and consumed by the Ash relationship management in the action.
 
   See the [DSL cheat sheet](DSL-Diffo.Provider.Instance.Extension.html) for the full DSL reference.
-  See `Diffo.Provider.BaseInstance` for full usage documentation.
+  See `Diffo.Provider.BaseInstance` for full usage documentation including generated functions.
   """
+
+  # ── structure ──────────────────────────────────────────────────────────────
+
   @specification %Spark.Dsl.Section{
     name: :specification,
     describe: "Defines the Instance Specification",
@@ -31,43 +59,31 @@ defmodule Diffo.Provider.Instance.Extension do
     schema: [
       id: [
         type: :string,
-        doc: """
-        The id of the specification, a uuid4 the same in all environments, unique for name and major_version.
-        """,
+        doc: "The id of the specification, a uuid4 the same in all environments, unique for name and major_version.",
         required: true
       ],
       name: [
         type: :string,
-        doc: """
-        The name of the specification, unique to a service but common for all versions.
-        """,
+        doc: "The name of the specification, unique to a service but common for all versions.",
         required: true
       ],
       type: [
         type: :atom,
-        doc: """
-        The type of the specification.
-        """,
+        doc: "The type of the specification.",
         default: :serviceSpecification
       ],
       major_version: [
         type: :integer,
-        doc: """
-        The major_version of the specification.
-        """,
+        doc: "The major_version of the specification.",
         default: 1
       ],
       description: [
         type: :string,
-        doc: """
-        A generic description of the specified service or resource.
-        """
+        doc: "A generic description of the specified service or resource."
       ],
       category: [
         type: :string,
-        doc: """
-        The category the specified service or resource belongs to.
-        """
+        doc: "The category the specified service or resource belongs to."
       ]
     ]
   }
@@ -79,17 +95,12 @@ defmodule Diffo.Provider.Instance.Extension do
     args: [:name, :value_type],
     schema: [
       name: [
-        doc: """
-          The name of the characteristic, an atom
-        """,
+        doc: "The name of the characteristic, an atom",
         type: :atom,
         required: true
       ],
       value_type: [
-        doc: """
-          The type of the characteristic's value. An atom module name such as an Ash.TypedStruct for a scalar value,
-          or `{:array, module}` for an array of values of that type.
-        """,
+        doc: "The type of the characteristic's value. An atom module name such as an Ash.TypedStruct for a scalar value, or `{:array, module}` for an array of values of that type.",
         type: :any
       ]
     ]
@@ -108,9 +119,7 @@ defmodule Diffo.Provider.Instance.Extension do
       end
       """
     ],
-    entities: [
-      @characteristic
-    ]
+    entities: [@characteristic]
   }
 
   @feature %Spark.Dsl.Entity{
@@ -120,16 +129,12 @@ defmodule Diffo.Provider.Instance.Extension do
     args: [:name],
     schema: [
       name: [
-        doc: """
-          The name of the feature, an atom
-        """,
+        doc: "The name of the feature, an atom",
         type: :atom,
         required: true
       ],
       is_enabled?: [
-        doc: """
-          Whether the feature is enabled by default, defaults true
-        """,
+        doc: "Whether the feature is enabled by default, defaults true",
         type: :boolean
       ]
     ],
@@ -153,9 +158,7 @@ defmodule Diffo.Provider.Instance.Extension do
       end
       """
     ],
-    entities: [
-      @feature
-    ]
+    entities: [@feature]
   }
 
   @party_schema [
@@ -216,12 +219,108 @@ defmodule Diffo.Provider.Instance.Extension do
       end
       """
     ],
-    entities: [
-      @party_entity,
-      @parties_entity
+    entities: [@party_entity, @parties_entity]
+  }
+
+  @structure %Spark.Dsl.Section{
+    name: :structure,
+    describe: "Defines the structural shape of the Instance — its specification, characteristics, features, and parties",
+    examples: [
+      """
+      structure do
+        specification do
+          id "da9b207a-26c3-451d-8abd-0640c6349979"
+          name "DSL Access Service"
+          type :serviceSpecification
+        end
+
+        characteristics do
+          characteristic :circuit, Diffo.Access.Circuit
+        end
+
+        parties do
+          party :provider, MyApp.Provider
+        end
+      end
+      """
+    ],
+    sections: [@specification, @characteristics, @features, @parties]
+  }
+
+  # ── behaviour ──────────────────────────────────────────────────────────────
+
+  @action_create %Spark.Dsl.Entity{
+    name: :create,
+    describe: "Marks a create action for instance build wiring, injecting :specified_by, :features, and :characteristics arguments",
+    target: Diffo.Provider.Instance.Extension.ActionCreate,
+    args: [:name],
+    schema: [
+      name: [
+        type: :atom,
+        required: true,
+        doc: "The name of the create action to wire"
+      ]
     ]
   }
 
+  @action_update %Spark.Dsl.Entity{
+    name: :update,
+    describe: "Marks an update action for instance behaviour wiring",
+    target: Diffo.Provider.Instance.Extension.ActionUpdate,
+    args: [:name],
+    schema: [
+      name: [
+        type: :atom,
+        required: true,
+        doc: "The name of the update action to wire"
+      ]
+    ]
+  }
+
+  @behaviour_actions %Spark.Dsl.Section{
+    name: :actions,
+    describe: "Declares which actions to wire for instance behaviour",
+    examples: [
+      """
+      actions do
+        create :build
+        update :define
+      end
+      """
+    ],
+    entities: [@action_create, @action_update]
+  }
+
+  @behaviour_section %Spark.Dsl.Section{
+    name: :behaviour,
+    describe: "Defines the behavioural wiring for the Instance — actions, and in future triggers and tasks",
+    examples: [
+      """
+      behaviour do
+        actions do
+          create :build
+          update :define
+        end
+      end
+      """
+    ],
+    sections: [@behaviour_actions]
+  }
+
   use Spark.Dsl.Extension,
-    sections: [@specification, @features, @characteristics, @parties]
+    sections: [@structure, @behaviour_section],
+    persisters: [
+      Diffo.Provider.Instance.Extension.Persisters.PersistSpecification,
+      Diffo.Provider.Instance.Extension.Persisters.PersistCharacteristics,
+      Diffo.Provider.Instance.Extension.Persisters.PersistFeatures,
+      Diffo.Provider.Instance.Extension.Persisters.PersistParties,
+      Diffo.Provider.Instance.Extension.Transformers.TransformBehaviour
+    ],
+    verifiers: [
+      Diffo.Provider.Instance.Extension.Verifiers.VerifySpecification,
+      Diffo.Provider.Instance.Extension.Verifiers.VerifyCharacteristics,
+      Diffo.Provider.Instance.Extension.Verifiers.VerifyFeatures,
+      Diffo.Provider.Instance.Extension.Verifiers.VerifyParties,
+      Diffo.Provider.Instance.Extension.Verifiers.VerifyBehaviour
+    ]
 end
diff --git a/lib/diffo/provider/components/instance/extension/action_create.ex b/lib/diffo/provider/components/instance/extension/action_create.ex
new file mode 100644
index 0000000..db5e0c7
--- /dev/null
+++ b/lib/diffo/provider/components/instance/extension/action_create.ex
@@ -0,0 +1,8 @@
+# SPDX-FileCopyrightText: 2025 diffo contributors <https://github.com/diffo-dev/diffo/graphs.contributors>
+#
+# SPDX-License-Identifier: MIT
+
+defmodule Diffo.Provider.Instance.Extension.ActionCreate do
+  @moduledoc false
+  defstruct [:name, __spark_metadata__: nil]
+end
diff --git a/lib/diffo/provider/components/instance/extension/action_helper.ex b/lib/diffo/provider/components/instance/extension/action_helper.ex
index 8dfa7c1..1d814d4 100644
--- a/lib/diffo/provider/components/instance/extension/action_helper.ex
+++ b/lib/diffo/provider/components/instance/extension/action_helper.ex
@@ -11,28 +11,17 @@ defmodule Diffo.Provider.Instance.ActionHelper do
   alias Diffo.Provider.Instance.Place
   alias Diffo.Provider.Instance.Party
 
-  @doc """
-  build before_action helper, injects instance dsl configuration into the changeset
-  """
-  def build_before(changeset) do
-    changeset
-    |> Specification.set_specified_by_argument()
-    |> Feature.set_features_argument()
-    |> Characteristic.set_characteristics_argument()
-    |> Party.validate_parties()
-  end
+  @doc false
+  def build_after(changeset, result) do
+    specified_by = Ash.Changeset.get_argument(changeset, :specified_by)
+    result = %{result | specification_id: specified_by}
 
-  @doc """
-  build after_action helper, relates TMF entities to the new instance
-  """
-  def build_after(changeset, result, module, function) do
-    with {:ok, result} <- Specification.relate_instance(result, changeset),
-         {:ok, result} <- Relationship.relate_instance(result, changeset),
-         {:ok, result} <- Feature.relate_instance(result, changeset),
-         {:ok, result} <- Characteristic.relate_instance(result, changeset),
-         {:ok, result} <- Place.relate_instance(result, changeset),
-         {:ok, result} <- Party.relate_instance(result, changeset),
-         {:ok, result} <- apply(module, function, [result.id]),
-         do: {:ok, result}
+    with {:ok, _} <- Specification.relate_instance(result, changeset),
+         {:ok, _} <- Relationship.relate_instance(result, changeset),
+         {:ok, _} <- Feature.relate_instance(result, changeset),
+         {:ok, _} <- Characteristic.relate_instance(result, changeset),
+         {:ok, _} <- Place.relate_instance(result, changeset),
+         {:ok, _} <- Party.relate_instance(result, changeset),
+         do: Ash.load(result, [:specification, :characteristics, :features, :parties])
   end
 end
diff --git a/lib/diffo/provider/components/instance/extension/action_update.ex b/lib/diffo/provider/components/instance/extension/action_update.ex
new file mode 100644
index 0000000..2678c43
--- /dev/null
+++ b/lib/diffo/provider/components/instance/extension/action_update.ex
@@ -0,0 +1,8 @@
+# SPDX-FileCopyrightText: 2025 diffo contributors <https://github.com/diffo-dev/diffo/graphs.contributors>
+#
+# SPDX-License-Identifier: MIT
+
+defmodule Diffo.Provider.Instance.Extension.ActionUpdate do
+  @moduledoc false
+  defstruct [:name, __spark_metadata__: nil]
+end
diff --git a/lib/diffo/provider/components/instance/extension/changes/build_after.ex b/lib/diffo/provider/components/instance/extension/changes/build_after.ex
new file mode 100644
index 0000000..2f9e586
--- /dev/null
+++ b/lib/diffo/provider/components/instance/extension/changes/build_after.ex
@@ -0,0 +1,15 @@
+# SPDX-FileCopyrightText: 2025 diffo contributors <https://github.com/diffo-dev/diffo/graphs.contributors>
+#
+# SPDX-License-Identifier: MIT
+
+defmodule Diffo.Provider.Instance.Extension.Changes.BuildAfter do
+  @moduledoc false
+  use Ash.Resource.Change
+
+  @impl true
+  def change(changeset, _opts, _context) do
+    Ash.Changeset.after_action(changeset, fn changeset, result ->
+      changeset.resource.build_after(changeset, result)
+    end)
+  end
+end
diff --git a/lib/diffo/provider/components/instance/extension/changes/build_before.ex b/lib/diffo/provider/components/instance/extension/changes/build_before.ex
new file mode 100644
index 0000000..0797d81
--- /dev/null
+++ b/lib/diffo/provider/components/instance/extension/changes/build_before.ex
@@ -0,0 +1,15 @@
+# SPDX-FileCopyrightText: 2025 diffo contributors <https://github.com/diffo-dev/diffo/graphs.contributors>
+#
+# SPDX-License-Identifier: MIT
+
+defmodule Diffo.Provider.Instance.Extension.Changes.BuildBefore do
+  @moduledoc false
+  use Ash.Resource.Change
+
+  @impl true
+  def change(changeset, _opts, _context) do
+    Ash.Changeset.before_action(changeset, fn changeset ->
+      changeset.resource.build_before(changeset)
+    end)
+  end
+end
diff --git a/lib/diffo/provider/components/instance/extension/characteristic.ex b/lib/diffo/provider/components/instance/extension/characteristic.ex
index 43c8d1b..92226d3 100644
--- a/lib/diffo/provider/components/instance/extension/characteristic.ex
+++ b/lib/diffo/provider/components/instance/extension/characteristic.ex
@@ -8,7 +8,6 @@ defmodule Diffo.Provider.Instance.Characteristic do
 
   alias Diffo.Provider
   alias Diffo.Provider.Instance
-  alias Diffo.Provider.Instance.Extension.Info
   alias Diffo.Type.Value
 
   @doc """
@@ -19,10 +18,9 @@ defmodule Diffo.Provider.Instance.Characteristic do
   @doc """
   Sets the Extended Instances characteristics argument in the changeset, creating the characteristics
   """
-  def set_characteristics_argument(changeset) when is_struct(changeset, Ash.Changeset) do
-    %module{} = changeset.data
-
-    case characteristics = create_characteristics(module, :instance) do
+  def set_characteristics_argument(changeset, declarations)
+      when is_struct(changeset, Ash.Changeset) and is_list(declarations) do
+    case characteristics = create_characteristics_from_declarations(declarations, :instance) do
       [] ->
         changeset
 
@@ -35,13 +33,8 @@ defmodule Diffo.Provider.Instance.Characteristic do
     end
   end
 
-  @doc """
-  Creates the Characteristics from a Extended Instance's module
-  """
-  def create_characteristics(module, type) when is_atom(module) and is_atom(type) do
-    characteristics = Info.characteristics(module)
-
-    Enum.reduce_while(characteristics, [], fn %{name: name, value_type: value_type}, acc ->
+  defp create_characteristics_from_declarations(declarations, type) do
+    Enum.reduce_while(declarations, [], fn %{name: name, value_type: value_type}, acc ->
       try do
         attrs =
           case value_type do
@@ -73,8 +66,7 @@ defmodule Diffo.Provider.Instance.Characteristic do
   def relate_instance(result, changeset)
       when is_struct(result) and is_struct(changeset, Ash.Changeset) do
     characteristics = Ash.Changeset.get_argument(changeset, :characteristics)
-    instance = struct(Instance, Map.from_struct(result))
-    Provider.relate_instance_characteristics(instance, %{characteristics: characteristics})
+    Provider.relate_instance_characteristics(%Instance{id: result.id}, %{characteristics: characteristics})
   end
 
   @doc """
diff --git a/lib/diffo/provider/components/instance/extension/feature.ex b/lib/diffo/provider/components/instance/extension/feature.ex
index 9428419..f0c8c75 100644
--- a/lib/diffo/provider/components/instance/extension/feature.ex
+++ b/lib/diffo/provider/components/instance/extension/feature.ex
@@ -8,7 +8,6 @@ defmodule Diffo.Provider.Instance.Feature do
 
   alias Diffo.Provider
   alias Diffo.Provider.Instance
-  alias Diffo.Provider.Instance.Extension.Info
   alias Diffo.Type.Value
 
   @doc """
@@ -19,10 +18,9 @@ defmodule Diffo.Provider.Instance.Feature do
   @doc """
   Sets the Extended Instances features argument in the changeset, creating the features and feature characteristics
   """
-  def set_features_argument(changeset) when is_struct(changeset, Ash.Changeset) do
-    %module{} = changeset.data
-
-    case features = create_features(module) do
+  def set_features_argument(changeset, declarations)
+      when is_struct(changeset, Ash.Changeset) and is_list(declarations) do
+    case features = create_features_from_declarations(declarations) do
       [] ->
         changeset
 
@@ -35,14 +33,9 @@ defmodule Diffo.Provider.Instance.Feature do
     end
   end
 
-  @doc """
-  Creates the Features from a Extended Instance's module
-  """
-  def create_features(module) when is_atom(module) do
-    features = Info.features(module)
-
+  defp create_features_from_declarations(declarations) do
     Enum.reduce_while(
-      features,
+      declarations,
       [],
       # create any feature characteristics
       fn %{name: name, is_enabled?: isEnabled, characteristics: characteristics}, acc ->
@@ -101,8 +94,7 @@ defmodule Diffo.Provider.Instance.Feature do
   def relate_instance(result, changeset)
       when is_struct(result) and is_struct(changeset, Ash.Changeset) do
     features = Ash.Changeset.get_argument(changeset, :features)
-    instance = struct(Instance, Map.from_struct(result))
-    Provider.relate_instance_features(instance, %{features: features})
+    Provider.relate_instance_features(%Instance{id: result.id}, %{features: features})
   end
 
   defimpl String.Chars do
diff --git a/lib/diffo/provider/components/instance/extension/info.ex b/lib/diffo/provider/components/instance/extension/info.ex
index 27c87d2..3356537 100644
--- a/lib/diffo/provider/components/instance/extension/info.ex
+++ b/lib/diffo/provider/components/instance/extension/info.ex
@@ -5,5 +5,12 @@
 defmodule Diffo.Provider.Instance.Extension.Info do
   use Spark.InfoGenerator,
     extension: Diffo.Provider.Instance.Extension,
-    sections: [:specification, :features, :characteristics, :parties]
+    sections: [:structure]
+
+  @doc "Returns true if the module is a BaseInstance-derived resource"
+  @spec instance?(module()) :: boolean()
+  def instance?(module) do
+    Code.ensure_loaded?(module) and
+      Diffo.Provider.Instance.Extension in Ash.Resource.Info.extensions(module)
+  end
 end
diff --git a/lib/diffo/provider/components/instance/extension/party.ex b/lib/diffo/provider/components/instance/extension/party.ex
index 9505d51..26bb9b4 100644
--- a/lib/diffo/provider/components/instance/extension/party.ex
+++ b/lib/diffo/provider/components/instance/extension/party.ex
@@ -5,7 +5,6 @@
 defmodule Diffo.Provider.Instance.Party do
   @moduledoc false
   alias Diffo.Provider
-  alias Diffo.Provider.Instance.Extension.Info, as: InstanceInfo
 
   @doc """
   Struct for a Party
@@ -13,9 +12,7 @@ defmodule Diffo.Provider.Instance.Party do
   defstruct [:id, :role]
 
   @doc false
-  def validate_parties(changeset) do
-    declarations = InstanceInfo.parties(changeset.resource)
-
+  def validate_parties(changeset, declarations) do
     if declarations == [] do
       changeset
     else
diff --git a/lib/diffo/provider/components/instance/extension/persisters/persist_characteristics.ex b/lib/diffo/provider/components/instance/extension/persisters/persist_characteristics.ex
new file mode 100644
index 0000000..e622fcc
--- /dev/null
+++ b/lib/diffo/provider/components/instance/extension/persisters/persist_characteristics.ex
@@ -0,0 +1,21 @@
+# SPDX-FileCopyrightText: 2025 diffo contributors <https://github.com/diffo-dev/diffo/graphs.contributors>
+#
+# SPDX-License-Identifier: MIT
+
+defmodule Diffo.Provider.Instance.Extension.Persisters.PersistCharacteristics do
+  @moduledoc "Persists characteristic declarations and bakes characteristics/0"
+  use Spark.Dsl.Transformer
+  alias Spark.Dsl.Transformer
+
+  @impl true
+  def transform(dsl_state) do
+    declarations = Transformer.get_entities(dsl_state, [:structure, :characteristics])
+    escaped = Macro.escape(declarations)
+    dsl_state = Transformer.persist(dsl_state, :characteristics, declarations)
+
+    {:ok, Transformer.eval(dsl_state, [], quote do
+      @doc false
+      def characteristics, do: unquote(escaped)
+    end)}
+  end
+end
diff --git a/lib/diffo/provider/components/instance/extension/persisters/persist_features.ex b/lib/diffo/provider/components/instance/extension/persisters/persist_features.ex
new file mode 100644
index 0000000..53fd427
--- /dev/null
+++ b/lib/diffo/provider/components/instance/extension/persisters/persist_features.ex
@@ -0,0 +1,21 @@
+# SPDX-FileCopyrightText: 2025 diffo contributors <https://github.com/diffo-dev/diffo/graphs.contributors>
+#
+# SPDX-License-Identifier: MIT
+
+defmodule Diffo.Provider.Instance.Extension.Persisters.PersistFeatures do
+  @moduledoc "Persists feature declarations and bakes features/0"
+  use Spark.Dsl.Transformer
+  alias Spark.Dsl.Transformer
+
+  @impl true
+  def transform(dsl_state) do
+    declarations = Transformer.get_entities(dsl_state, [:structure, :features])
+    escaped = Macro.escape(declarations)
+    dsl_state = Transformer.persist(dsl_state, :features, declarations)
+
+    {:ok, Transformer.eval(dsl_state, [], quote do
+      @doc false
+      def features, do: unquote(escaped)
+    end)}
+  end
+end
diff --git a/lib/diffo/provider/components/instance/extension/persisters/persist_parties.ex b/lib/diffo/provider/components/instance/extension/persisters/persist_parties.ex
new file mode 100644
index 0000000..ff25478
--- /dev/null
+++ b/lib/diffo/provider/components/instance/extension/persisters/persist_parties.ex
@@ -0,0 +1,21 @@
+# SPDX-FileCopyrightText: 2025 diffo contributors <https://github.com/diffo-dev/diffo/graphs.contributors>
+#
+# SPDX-License-Identifier: MIT
+
+defmodule Diffo.Provider.Instance.Extension.Persisters.PersistParties do
+  @moduledoc "Persists party declarations and bakes parties/0"
+  use Spark.Dsl.Transformer
+  alias Spark.Dsl.Transformer
+
+  @impl true
+  def transform(dsl_state) do
+    declarations = Transformer.get_entities(dsl_state, [:structure, :parties])
+    escaped = Macro.escape(declarations)
+    dsl_state = Transformer.persist(dsl_state, :parties, declarations)
+
+    {:ok, Transformer.eval(dsl_state, [], quote do
+      @doc false
+      def parties, do: unquote(escaped)
+    end)}
+  end
+end
diff --git a/lib/diffo/provider/components/instance/extension/persisters/persist_specification.ex b/lib/diffo/provider/components/instance/extension/persisters/persist_specification.ex
new file mode 100644
index 0000000..4cfd5f9
--- /dev/null
+++ b/lib/diffo/provider/components/instance/extension/persisters/persist_specification.ex
@@ -0,0 +1,29 @@
+# SPDX-FileCopyrightText: 2025 diffo contributors <https://github.com/diffo-dev/diffo/graphs.contributors>
+#
+# SPDX-License-Identifier: MIT
+
+defmodule Diffo.Provider.Instance.Extension.Persisters.PersistSpecification do
+  @moduledoc "Normalises specification DSL options, persists them, and bakes specification/0"
+  use Spark.Dsl.Transformer
+  alias Spark.Dsl.Transformer
+
+  @impl true
+  def transform(dsl_state) do
+    spec = [
+      id: Transformer.get_option(dsl_state, [:structure, :specification], :id),
+      name: Transformer.get_option(dsl_state, [:structure, :specification], :name),
+      type: Transformer.get_option(dsl_state, [:structure, :specification], :type, :serviceSpecification),
+      major_version: Transformer.get_option(dsl_state, [:structure, :specification], :major_version, 1),
+      description: Transformer.get_option(dsl_state, [:structure, :specification], :description),
+      category: Transformer.get_option(dsl_state, [:structure, :specification], :category)
+    ]
+
+    escaped = Macro.escape(spec)
+    dsl_state = Transformer.persist(dsl_state, :specification, spec)
+
+    {:ok, Transformer.eval(dsl_state, [], quote do
+      @doc false
+      def specification, do: unquote(escaped)
+    end)}
+  end
+end
diff --git a/lib/diffo/provider/components/instance/extension/specification.ex b/lib/diffo/provider/components/instance/extension/specification.ex
index 8f5720a..b40ed56 100644
--- a/lib/diffo/provider/components/instance/extension/specification.ex
+++ b/lib/diffo/provider/components/instance/extension/specification.ex
@@ -8,7 +8,6 @@ defmodule Diffo.Provider.Instance.Specification do
 
   alias Diffo.Provider
   alias Diffo.Provider.Instance
-  alias Diffo.Provider.Instance.Extension.Info
 
   @doc """
   Struct for a Specification
@@ -18,31 +17,16 @@ defmodule Diffo.Provider.Instance.Specification do
   @doc """
   Sets the specified_by argument in the changeset, ensuring the Extended Instance's specification exists
   """
-  def set_specified_by_argument(changeset) when is_struct(changeset, Ash.Changeset) do
-    %module{} = changeset.data
-    # ensure the specification exists
-    case upsert_specification(module) do
-      {:ok, specification} ->
-        Ash.Changeset.force_set_argument(changeset, :specified_by, specification.id)
-
-      {:error, error} ->
-        Ash.Changeset.add_error(changeset, error)
-    end
-  end
-
-  @doc """
-  Upserts the Specification from a Extended Instance's module
-  """
-  def upsert_specification(module) when is_atom(module) do
-    options = Info.specification_options(module)
+  def set_specified_by_argument(changeset, options)
+      when is_struct(changeset, Ash.Changeset) and is_list(options) do
     specification = struct(__MODULE__, options)
 
     case Provider.create_specification(Map.from_struct(specification)) do
-      {:ok, _result} ->
-        {:ok, specification}
+      {:ok, _} ->
+        Ash.Changeset.force_set_argument(changeset, :specified_by, specification.id)
 
       {:error, error} ->
-        {:error, error}
+        Ash.Changeset.add_error(changeset, error)
     end
   end
 
@@ -52,18 +36,7 @@ defmodule Diffo.Provider.Instance.Specification do
   def relate_instance(result, changeset)
       when is_struct(result) and is_struct(changeset, Ash.Changeset) do
     specified_by = Ash.Changeset.get_argument(changeset, :specified_by)
-    instance = struct(Instance, Map.from_struct(result))
-
-    case Provider.specify_instance(instance, %{specified_by: specified_by}) do
-      {:ok, specification} ->
-        {:ok,
-         result
-         |> Map.put(:specification, specification)
-         |> Map.put(:specification_id, specified_by)}
-
-      {:error, error} ->
-        {:error, error}
-    end
+    Provider.specify_instance(%Instance{id: result.id}, %{specified_by: specified_by})
   end
 
   defimpl String.Chars do
diff --git a/lib/diffo/provider/components/instance/extension/transformers/transform_behaviour.ex b/lib/diffo/provider/components/instance/extension/transformers/transform_behaviour.ex
new file mode 100644
index 0000000..5aea342
--- /dev/null
+++ b/lib/diffo/provider/components/instance/extension/transformers/transform_behaviour.ex
@@ -0,0 +1,104 @@
+# SPDX-FileCopyrightText: 2025 diffo contributors <https://github.com/diffo-dev/diffo/graphs.contributors>
+#
+# SPDX-License-Identifier: MIT
+
+defmodule Diffo.Provider.Instance.Extension.Transformers.TransformBehaviour do
+  @moduledoc "Generates build_before/1 and build_after/2, and injects build arguments into declared create actions"
+  use Spark.Dsl.Transformer
+  alias Spark.Dsl.Transformer
+  alias Diffo.Provider.Instance.Extension.ActionCreate
+
+  @build_args [
+    specified_by: :uuid,
+    features: {:array, :uuid},
+    characteristics: {:array, :uuid}
+  ]
+
+  @impl true
+  def transform(dsl_state) do
+    spec = Transformer.get_persisted(dsl_state, :specification, [])
+
+    dsl_state = inject_create_arguments(dsl_state)
+
+    {build_before_body, build_after_body} =
+      if spec[:id] do
+        before_body = quote do
+          changeset
+          |> Diffo.Provider.Instance.Specification.set_specified_by_argument(specification())
+          |> Diffo.Provider.Instance.Feature.set_features_argument(features())
+          |> Diffo.Provider.Instance.Characteristic.set_characteristics_argument(characteristics())
+          |> Diffo.Provider.Instance.Party.validate_parties(parties())
+        end
+
+        after_body = quote do
+          Diffo.Provider.Instance.ActionHelper.build_after(changeset, result)
+        end
+
+        {before_body, after_body}
+      else
+        {quote(do: changeset), quote(do: {:ok, result})}
+      end
+
+    {:ok, Transformer.eval(dsl_state, [], quote do
+      @doc false
+      def build_before(changeset), do: unquote(build_before_body)
+
+      @doc false
+      def build_after(changeset, result), do: unquote(build_after_body)
+
+      @doc false
+      def characteristic(name), do: Enum.find(characteristics(), &(&1.name == name))
+
+      @doc false
+      def feature(name), do: Enum.find(features(), &(&1.name == name))
+
+      @doc false
+      def feature_characteristic(feature_name, char_name) do
+        case feature(feature_name) do
+          nil -> nil
+          f -> Enum.find(f.characteristics, &(&1.name == char_name))
+        end
+      end
+
+      @doc false
+      def party(role), do: Enum.find(parties(), &(&1.role == role))
+    end)}
+  end
+
+  defp inject_create_arguments(dsl_state) do
+    action_create_declarations =
+      Transformer.get_entities(dsl_state, [:behaviour, :actions])
+      |> Enum.filter(&is_struct(&1, ActionCreate))
+
+    Enum.reduce(action_create_declarations, dsl_state, fn %ActionCreate{name: action_name}, dsl_state ->
+      action =
+        Transformer.get_entities(dsl_state, [:actions])
+        |> Enum.find(&(is_struct(&1, Ash.Resource.Actions.Create) and &1.name == action_name))
+
+      if action do
+        existing = MapSet.new(action.arguments, & &1.name)
+
+        new_args =
+          @build_args
+          |> Enum.reject(fn {name, _} -> MapSet.member?(existing, name) end)
+          |> Enum.map(fn {name, type} ->
+            %Ash.Resource.Actions.Argument{name: name, type: type, public?: false, allow_nil?: true}
+          end)
+
+        updated = %{action | arguments: action.arguments ++ new_args}
+        Transformer.replace_entity(dsl_state, [:actions], updated, fn entity ->
+          is_struct(entity, Ash.Resource.Actions.Create) and entity.name == action_name
+        end)
+      else
+        dsl_state
+      end
+    end)
+  end
+
+  @impl true
+  def after?(Diffo.Provider.Instance.Extension.Persisters.PersistSpecification), do: true
+  def after?(Diffo.Provider.Instance.Extension.Persisters.PersistCharacteristics), do: true
+  def after?(Diffo.Provider.Instance.Extension.Persisters.PersistFeatures), do: true
+  def after?(Diffo.Provider.Instance.Extension.Persisters.PersistParties), do: true
+  def after?(_), do: false
+end
diff --git a/lib/diffo/provider/components/instance/extension/verifiers/verify_behaviour.ex b/lib/diffo/provider/components/instance/extension/verifiers/verify_behaviour.ex
new file mode 100644
index 0000000..7cc10db
--- /dev/null
+++ b/lib/diffo/provider/components/instance/extension/verifiers/verify_behaviour.ex
@@ -0,0 +1,53 @@
+# SPDX-FileCopyrightText: 2025 diffo contributors <https://github.com/diffo-dev/diffo/graphs.contributors>
+#
+# SPDX-License-Identifier: MIT
+
+defmodule Diffo.Provider.Instance.Extension.Verifiers.VerifyBehaviour do
+  @moduledoc "Verifies that actions declared in behaviour do exist as Ash actions of the correct type"
+  use Spark.Dsl.Verifier
+
+  alias Spark.Dsl.Verifier
+  alias Spark.Error.DslError
+  alias Diffo.Provider.Instance.Extension.ActionCreate
+  alias Diffo.Provider.Instance.Extension.ActionUpdate
+
+  @impl true
+  def verify(dsl_state) do
+    resource = Verifier.get_persisted(dsl_state, :module)
+    behaviour_actions = Verifier.get_entities(dsl_state, [:behaviour, :actions])
+    ash_actions = Verifier.get_entities(dsl_state, [:actions])
+
+    create_names = ash_actions |> Enum.filter(&is_struct(&1, Ash.Resource.Actions.Create)) |> MapSet.new(& &1.name)
+    update_names = ash_actions |> Enum.filter(&is_struct(&1, Ash.Resource.Actions.Update)) |> MapSet.new(& &1.name)
+
+    errors =
+      Enum.flat_map(behaviour_actions, fn
+        %ActionCreate{name: name} ->
+          if MapSet.member?(create_names, name) do
+            []
+          else
+            [DslError.exception(
+              module: resource,
+              path: [:behaviour, :actions],
+              message: "behaviour: create #{inspect(name)} does not exist as a create action on this resource"
+            )]
+          end
+
+        %ActionUpdate{name: name} ->
+          if MapSet.member?(update_names, name) do
+            []
+          else
+            [DslError.exception(
+              module: resource,
+              path: [:behaviour, :actions],
+              message: "behaviour: update #{inspect(name)} does not exist as an update action on this resource"
+            )]
+          end
+      end)
+
+    case errors do
+      [] -> :ok
+      errors -> {:error, errors}
+    end
+  end
+end
diff --git a/lib/diffo/provider/components/instance/extension/verifiers/verify_characteristics.ex b/lib/diffo/provider/components/instance/extension/verifiers/verify_characteristics.ex
new file mode 100644
index 0000000..b81e133
--- /dev/null
+++ b/lib/diffo/provider/components/instance/extension/verifiers/verify_characteristics.ex
@@ -0,0 +1,62 @@
+# SPDX-FileCopyrightText: 2025 diffo contributors <https://github.com/diffo-dev/diffo/graphs.contributors>
+#
+# SPDX-License-Identifier: MIT
+
+defmodule Diffo.Provider.Instance.Extension.Verifiers.VerifyCharacteristics do
+  @moduledoc "Verifies that characteristic names are unique and value_type modules exist"
+  use Spark.Dsl.Verifier
+
+  alias Spark.Dsl.Verifier
+  alias Spark.Error.DslError
+
+  @impl true
+  def verify(dsl_state) do
+    resource = Verifier.get_persisted(dsl_state, :module)
+    characteristics = Verifier.get_entities(dsl_state, [:structure, :characteristics])
+
+    duplicate_errors =
+      characteristics
+      |> Enum.group_by(& &1.name)
+      |> Enum.filter(fn {_name, chars} -> length(chars) > 1 end)
+      |> Enum.map(fn {name, _} ->
+        DslError.exception(
+          module: resource,
+          path: [:structure, :characteristics],
+          message: "characteristics: name #{inspect(name)} is declared more than once"
+        )
+      end)
+
+    type_errors =
+      Enum.reduce(characteristics, [], fn char, acc ->
+        case module_from_value_type(char.value_type) do
+          {:ok, module} ->
+            if Code.ensure_loaded?(module) do
+              acc
+            else
+              [
+                DslError.exception(
+                  module: resource,
+                  path: [:structure, :characteristics, char.name],
+                  message: "characteristics: value_type #{inspect(module)} does not exist"
+                )
+                | acc
+              ]
+            end
+
+          :error ->
+            acc
+        end
+      end)
+
+    errors = duplicate_errors ++ type_errors
+
+    case errors do
+      [] -> :ok
+      errors -> {:error, errors}
+    end
+  end
+
+  defp module_from_value_type({:array, module}) when is_atom(module), do: {:ok, module}
+  defp module_from_value_type(module) when is_atom(module), do: {:ok, module}
+  defp module_from_value_type(_), do: :error
+end
diff --git a/lib/diffo/provider/components/instance/extension/verifiers/verify_features.ex b/lib/diffo/provider/components/instance/extension/verifiers/verify_features.ex
new file mode 100644
index 0000000..d85e65f
--- /dev/null
+++ b/lib/diffo/provider/components/instance/extension/verifiers/verify_features.ex
@@ -0,0 +1,76 @@
+# SPDX-FileCopyrightText: 2025 diffo contributors <https://github.com/diffo-dev/diffo/graphs.contributors>
+#
+# SPDX-License-Identifier: MIT
+
+defmodule Diffo.Provider.Instance.Extension.Verifiers.VerifyFeatures do
+  @moduledoc "Verifies that feature names are unique, feature characteristic names are unique, and value_type modules exist"
+  use Spark.Dsl.Verifier
+
+  alias Spark.Dsl.Verifier
+  alias Spark.Error.DslError
+
+  @impl true
+  def verify(dsl_state) do
+    resource = Verifier.get_persisted(dsl_state, :module)
+    features = Verifier.get_entities(dsl_state, [:structure, :features])
+
+    duplicate_feature_errors =
+      features
+      |> Enum.group_by(& &1.name)
+      |> Enum.filter(fn {_name, fs} -> length(fs) > 1 end)
+      |> Enum.map(fn {name, _} ->
+        DslError.exception(
+          module: resource,
+          path: [:structure, :features],
+          message: "features: name #{inspect(name)} is declared more than once"
+        )
+      end)
+
+    type_errors =
+      Enum.reduce(features, [], fn feature, acc ->
+        duplicate_char_errors =
+          feature.characteristics
+          |> Enum.group_by(& &1.name)
+          |> Enum.filter(fn {_name, chars} -> length(chars) > 1 end)
+          |> Enum.map(fn {name, _} ->
+            DslError.exception(
+              module: resource,
+              path: [:structure, :features, feature.name, :characteristics],
+              message: "features: characteristic name #{inspect(name)} is declared more than once in #{inspect(feature.name)}"
+            )
+          end)
+
+        Enum.reduce(feature.characteristics, acc ++ duplicate_char_errors, fn char, inner_acc ->
+          case module_from_value_type(char.value_type) do
+            {:ok, module} ->
+              if Code.ensure_loaded?(module) do
+                inner_acc
+              else
+                [
+                  DslError.exception(
+                    module: resource,
+                    path: [:structure, :features, feature.name, :characteristics, char.name],
+                    message: "features: characteristic value_type #{inspect(module)} does not exist"
+                  )
+                  | inner_acc
+                ]
+              end
+
+            :error ->
+              inner_acc
+          end
+        end)
+      end)
+
+    errors = duplicate_feature_errors ++ type_errors
+
+    case errors do
+      [] -> :ok
+      errors -> {:error, errors}
+    end
+  end
+
+  defp module_from_value_type({:array, module}) when is_atom(module), do: {:ok, module}
+  defp module_from_value_type(module) when is_atom(module), do: {:ok, module}
+  defp module_from_value_type(_), do: :error
+end
diff --git a/lib/diffo/provider/components/instance/extension/verifiers/verify_parties.ex b/lib/diffo/provider/components/instance/extension/verifiers/verify_parties.ex
new file mode 100644
index 0000000..63bd593
--- /dev/null
+++ b/lib/diffo/provider/components/instance/extension/verifiers/verify_parties.ex
@@ -0,0 +1,68 @@
+# SPDX-FileCopyrightText: 2025 diffo contributors <https://github.com/diffo-dev/diffo/graphs.contributors>
+#
+# SPDX-License-Identifier: MIT
+
+defmodule Diffo.Provider.Instance.Extension.Verifiers.VerifyParties do
+  @moduledoc "Verifies party role declarations — no duplicates, party_type modules must exist"
+  use Spark.Dsl.Verifier
+
+  alias Spark.Dsl.Verifier
+  alias Spark.Error.DslError
+  alias Diffo.Provider.Party.Extension.Info, as: PartyInfo
+
+  @impl true
+  def verify(dsl_state) do
+    resource = Verifier.get_persisted(dsl_state, :module)
+    parties = Verifier.get_entities(dsl_state, [:structure, :parties])
+
+    duplicate_errors =
+      parties
+      |> Enum.group_by(& &1.role)
+      |> Enum.filter(fn {_role, declarations} -> length(declarations) > 1 end)
+      |> Enum.map(fn {role, _} ->
+        DslError.exception(
+          module: resource,
+          path: [:structure, :parties],
+          message: "parties: role #{inspect(role)} is declared more than once"
+        )
+      end)
+
+    type_errors =
+      Enum.reduce(parties, [], fn party, acc ->
+        cond do
+          is_nil(party.party_type) ->
+            acc
+
+          !Code.ensure_loaded?(party.party_type) ->
+            [
+              DslError.exception(
+                module: resource,
+                path: [:structure, :parties, party.role],
+                message: "parties: party_type #{inspect(party.party_type)} does not exist"
+              )
+              | acc
+            ]
+
+          !PartyInfo.party?(party.party_type) ->
+            [
+              DslError.exception(
+                module: resource,
+                path: [:structure, :parties, party.role],
+                message: "parties: party_type #{inspect(party.party_type)} does not extend BaseParty"
+              )
+              | acc
+            ]
+
+          true ->
+            acc
+        end
+      end)
+
+    errors = duplicate_errors ++ type_errors
+
+    case errors do
+      [] -> :ok
+      errors -> {:error, errors}
+    end
+  end
+end
diff --git a/lib/diffo/provider/components/instance/extension/verifiers/verify_specification.ex b/lib/diffo/provider/components/instance/extension/verifiers/verify_specification.ex
new file mode 100644
index 0000000..2368126
--- /dev/null
+++ b/lib/diffo/provider/components/instance/extension/verifiers/verify_specification.ex
@@ -0,0 +1,35 @@
+# SPDX-FileCopyrightText: 2025 diffo contributors <https://github.com/diffo-dev/diffo/graphs.contributors>
+#
+# SPDX-License-Identifier: MIT
+
+defmodule Diffo.Provider.Instance.Extension.Verifiers.VerifySpecification do
+  @moduledoc "Verifies that the specification id is a valid UUID4"
+  use Spark.Dsl.Verifier
+
+  alias Spark.Dsl.Verifier
+  alias Spark.Error.DslError
+
+  @impl true
+  def verify(dsl_state) do
+    resource = Verifier.get_persisted(dsl_state, :module)
+    spec_id = Verifier.get_option(dsl_state, [:structure, :specification], :id)
+
+    errors =
+      if spec_id && !Diffo.Uuid.uuid4?(spec_id) do
+        [
+          DslError.exception(
+            module: resource,
+            path: [:structure, :specification, :id],
+            message: "specification: id must be a valid UUID4"
+          )
+        ]
+      else
+        []
+      end
+
+    case errors do
+      [] -> :ok
+      errors -> {:error, errors}
+    end
+  end
+end
diff --git a/lib/diffo/provider/components/instance/info.ex b/lib/diffo/provider/components/instance/info.ex
new file mode 100644
index 0000000..ae17ac9
--- /dev/null
+++ b/lib/diffo/provider/components/instance/info.ex
@@ -0,0 +1,60 @@
+# SPDX-FileCopyrightText: 2025 diffo contributors <https://github.com/diffo-dev/diffo/graphs.contributors>
+#
+# SPDX-License-Identifier: MIT
+
+defmodule Diffo.Provider.Instance.Info do
+  @moduledoc "Public introspection API for resources extending Diffo.Provider.BaseInstance"
+
+  alias Spark.Dsl.Extension
+
+  @doc "Returns the normalised specification keyword list for the resource"
+  @spec specification(Ash.Resource.t()) :: keyword() | nil
+  def specification(resource) do
+    Extension.get_persisted(resource, :specification)
+  end
+
+  @doc "Returns the list of characteristic declarations for the resource"
+  @spec characteristics(Ash.Resource.t()) :: list() | []
+  def characteristics(resource) do
+    Extension.get_persisted(resource, :characteristics, [])
+  end
+
+  @doc "Returns the list of feature declarations for the resource"
+  @spec features(Ash.Resource.t()) :: list() | []
+  def features(resource) do
+    Extension.get_persisted(resource, :features, [])
+  end
+
+  @doc "Returns the list of party role declarations for the resource"
+  @spec parties(Ash.Resource.t()) :: list() | []
+  def parties(resource) do
+    Extension.get_persisted(resource, :parties, [])
+  end
+
+  @doc "Returns the named characteristic declaration, or nil"
+  @spec characteristic(Ash.Resource.t(), atom()) :: struct() | nil
+  def characteristic(resource, name) do
+    Enum.find(characteristics(resource), &(&1.name == name))
+  end
+
+  @doc "Returns the named feature declaration, or nil"
+  @spec feature(Ash.Resource.t(), atom()) :: struct() | nil
+  def feature(resource, name) do
+    Enum.find(features(resource), &(&1.name == name))
+  end
+
+  @doc "Returns the named characteristic within a feature, or nil"
+  @spec feature_characteristic(Ash.Resource.t(), atom(), atom()) :: struct() | nil
+  def feature_characteristic(resource, feature_name, char_name) do
+    case feature(resource, feature_name) do
+      nil -> nil
+      f -> Enum.find(f.characteristics, &(&1.name == char_name))
+    end
+  end
+
+  @doc "Returns the party declaration for the given role, or nil"
+  @spec party(Ash.Resource.t(), atom()) :: struct() | nil
+  def party(resource, role) do
+    Enum.find(parties(resource), &(&1.role == role))
+  end
+end
diff --git a/lib/diffo/provider/components/party/extension/info.ex b/lib/diffo/provider/components/party/extension/info.ex
index 5638989..8c29009 100644
--- a/lib/diffo/provider/components/party/extension/info.ex
+++ b/lib/diffo/provider/components/party/extension/info.ex
@@ -6,4 +6,11 @@ defmodule Diffo.Provider.Party.Extension.Info do
   use Spark.InfoGenerator,
     extension: Diffo.Provider.Party.Extension,
     sections: [:instances, :parties]
+
+  @doc "Returns true if the module is a BaseParty-derived resource"
+  @spec party?(module()) :: boolean()
+  def party?(module) do
+    Code.ensure_loaded?(module) and
+      Diffo.Provider.Party.Extension in Ash.Resource.Info.extensions(module)
+  end
 end
diff --git a/test/instance_extension/party_test.exs b/test/instance_extension/party_test.exs
index 35deb16..04c1a71 100644
--- a/test/instance_extension/party_test.exs
+++ b/test/instance_extension/party_test.exs
@@ -53,14 +53,14 @@ defmodule Diffo.InstanceExtension.PartyTest do
 
   describe "Instance DSL — Shelf parties" do
     test "party declarations are accessible via info" do
-      parties = InstanceInfo.parties(Shelf)
+      parties = InstanceInfo.structure_parties(Shelf)
       roles = Enum.map(parties, & &1.role)
       assert :facilitator in roles
       assert :overseer in roles
     end
 
     test "party types are correct" do
-      parties = InstanceInfo.parties(Shelf)
+      parties = InstanceInfo.structure_parties(Shelf)
       facilitator = Enum.find(parties, &(&1.role == :facilitator))
       overseer = Enum.find(parties, &(&1.role == :overseer))
       assert facilitator.party_type == Organization
@@ -68,38 +68,38 @@ defmodule Diffo.InstanceExtension.PartyTest do
     end
 
     test "singular party defaults to multiple: false" do
-      parties = InstanceInfo.parties(Shelf)
+      parties = InstanceInfo.structure_parties(Shelf)
       facilitator = Enum.find(parties, &(&1.role == :facilitator))
       assert facilitator.multiple == false
     end
 
     test "reference: true is declared" do
-      parties = InstanceInfo.parties(Shelf)
+      parties = InstanceInfo.structure_parties(Shelf)
       provider = Enum.find(parties, &(&1.role == :provider))
       assert provider.reference == true
       assert provider.multiple == false
     end
 
     test "reference defaults to false" do
-      parties = InstanceInfo.parties(Shelf)
+      parties = InstanceInfo.structure_parties(Shelf)
       facilitator = Enum.find(parties, &(&1.role == :facilitator))
       assert facilitator.reference == false
     end
 
     test "calculate: is declared" do
-      parties = InstanceInfo.parties(Shelf)
+      parties = InstanceInfo.structure_parties(Shelf)
       manager = Enum.find(parties, &(&1.role == :manager))
       assert manager.calculate == :manager_calc
     end
 
     test "parties (plural) sets multiple: true" do
-      parties = InstanceInfo.parties(Shelf)
+      parties = InstanceInfo.structure_parties(Shelf)
       installer = Enum.find(parties, &(&1.role == :installer))
       assert installer.multiple == true
     end
 
     test "parties (plural) constraints are declared" do
-      parties = InstanceInfo.parties(Shelf)
+      parties = InstanceInfo.structure_parties(Shelf)
       installer = Enum.find(parties, &(&1.role == :installer))
       assert installer.constraints == [min: 1, max: 3]
     end
diff --git a/test/instance_extension/transformer_test.exs b/test/instance_extension/transformer_test.exs
new file mode 100644
index 0000000..2d9363a
--- /dev/null
+++ b/test/instance_extension/transformer_test.exs
@@ -0,0 +1,245 @@
+# SPDX-FileCopyrightText: 2025 diffo contributors <https://github.com/diffo-dev/diffo/graphs.contributors>
+#
+# SPDX-License-Identifier: MIT
+
+defmodule Diffo.InstanceExtension.TransformerTest do
+  @moduledoc false
+  use ExUnit.Case, async: true
+
+  alias Diffo.Test.Shelf
+  alias Diffo.Test.Card
+  alias Diffo.Provider.Instance.Characteristic
+  alias Diffo.Provider.Instance.Feature
+  alias Diffo.Provider.Instance.Info
+
+  describe "PersistSpecification" do
+    test "bakes specification/0 onto the resource" do
+      spec = Shelf.specification()
+      assert spec[:id] == "ef016d85-9dbd-429c-84da-1df56cc7dda5"
+      assert spec[:name] == "shelf"
+      assert spec[:type] == :resourceSpecification
+      assert spec[:description] == "A Shelf Resource Instance which contain cards"
+      assert spec[:category] == "Network Resource"
+      assert spec[:major_version] == 1
+    end
+
+    test "card specification is baked correctly" do
+      spec = Card.specification()
+      assert spec[:id] == "cd29956f-6c68-44cc-bf54-705eb8d2f754"
+      assert spec[:name] == "card"
+      assert spec[:type] == :resourceSpecification
+    end
+
+    test "specification is also accessible via Info" do
+      assert Info.specification(Shelf)[:name] == "shelf"
+      assert Info.specification(Card)[:name] == "card"
+    end
+  end
+
+  describe "PersistCharacteristics" do
+    test "bakes characteristics/0 onto the resource" do
+      chars = Shelf.characteristics()
+      assert is_list(chars)
+      assert length(chars) == 3
+      names = Enum.map(chars, & &1.name)
+      assert :shelf in names
+      assert :slots in names
+      assert :shelves in names
+    end
+
+    test "each characteristic is a Characteristic struct" do
+      [first | _] = Shelf.characteristics()
+      assert is_struct(first, Characteristic)
+    end
+
+    test "characteristics are also accessible via Info" do
+      assert length(Info.characteristics(Shelf)) == 3
+      assert length(Info.characteristics(Card)) == 2
+    end
+
+    test "Info.characteristic/2 returns the named characteristic" do
+      char = Info.characteristic(Shelf, :shelves)
+      assert char.name == :shelves
+    end
+
+    test "Info.characteristic/2 returns nil for unknown name" do
+      assert Info.characteristic(Shelf, :nonexistent) == nil
+    end
+  end
+
+  describe "PersistFeatures" do
+    test "bakes features/0 onto the resource" do
+      features = Shelf.features()
+      assert is_list(features)
+      assert length(features) == 1
+      [feature] = features
+      assert feature.name == :spectralManagement
+      assert feature.is_enabled? == true
+    end
+
+    test "each feature is a Feature struct" do
+      [feature] = Shelf.features()
+      assert is_struct(feature, Feature)
+    end
+
+    test "feature characteristics are nested in the declaration" do
+      [feature] = Shelf.features()
+      assert length(feature.characteristics) == 2
+      char_names = Enum.map(feature.characteristics, & &1.name)
+      assert :deploymentClass in char_names
+      assert :deploymentClasses in char_names
+    end
+
+    test "features are also accessible via Info" do
+      assert length(Info.features(Shelf)) == 1
+      assert Info.features(Card) == []
+    end
+
+    test "Info.feature/2 returns the named feature" do
+      feature = Info.feature(Shelf, :spectralManagement)
+      assert feature.name == :spectralManagement
+    end
+
+    test "Info.feature/2 returns nil for unknown name" do
+      assert Info.feature(Shelf, :nonexistent) == nil
+    end
+
+    test "Info.feature_characteristic/3 returns the named characteristic within a feature" do
+      char = Info.feature_characteristic(Shelf, :spectralManagement, :deploymentClass)
+      assert char.name == :deploymentClass
+    end
+
+    test "Info.feature_characteristic/3 returns nil for unknown feature" do
+      assert Info.feature_characteristic(Shelf, :nonexistent, :deploymentClass) == nil
+    end
+
+    test "Info.feature_characteristic/3 returns nil for unknown characteristic" do
+      assert Info.feature_characteristic(Shelf, :spectralManagement, :nonexistent) == nil
+    end
+  end
+
+  describe "PersistParties" do
+    test "bakes parties/0 onto the resource" do
+      parties = Shelf.parties()
+      assert is_list(parties)
+      assert length(parties) == 5
+      roles = Enum.map(parties, & &1.role)
+      assert :facilitator in roles
+      assert :overseer in roles
+      assert :provider in roles
+      assert :manager in roles
+      assert :installer in roles
+    end
+
+    test "reference party has reference flag set" do
+      provider = Enum.find(Shelf.parties(), &(&1.role == :provider))
+      assert provider.reference == true
+    end
+
+    test "calculate party has calculate set" do
+      manager = Enum.find(Shelf.parties(), &(&1.role == :manager))
+      assert manager.calculate == :manager_calc
+    end
+
+    test "plural party has constraints" do
+      installer = Enum.find(Shelf.parties(), &(&1.role == :installer))
+      assert installer.multiple == true
+      assert installer.constraints == [min: 1, max: 3]
+    end
+
+    test "parties are also accessible via Info" do
+      assert length(Info.parties(Shelf)) == 5
+      assert Info.parties(Card) == []
+    end
+
+    test "Info.party/2 returns the named party declaration by role" do
+      p = Info.party(Shelf, :facilitator)
+      assert p.role == :facilitator
+    end
+
+    test "Info.party/2 returns nil for unknown role" do
+      assert Info.party(Shelf, :nonexistent) == nil
+    end
+  end
+
+  describe "TransformBehaviour" do
+    setup do
+      Code.ensure_loaded!(Shelf)
+      Code.ensure_loaded!(Card)
+      :ok
+    end
+
+    test "build_before/1 is defined on shelf" do
+      assert function_exported?(Shelf, :build_before, 1)
+    end
+
+    test "build_after/2 is defined on shelf" do
+      assert function_exported?(Shelf, :build_after, 2)
+    end
+
+    test "build_before/1 is defined on card" do
+      assert function_exported?(Card, :build_before, 1)
+    end
+
+    test "build_after/2 is defined on card" do
+      assert function_exported?(Card, :build_after, 2)
+    end
+
+    test "action_create injects :specified_by argument into :build" do
+      action = Ash.Resource.Info.action(Shelf, :build)
+      arg_names = Enum.map(action.arguments, & &1.name)
+      assert :specified_by in arg_names
+      assert :features in arg_names
+      assert :characteristics in arg_names
+    end
+
+    test "injected arguments are not public" do
+      action = Ash.Resource.Info.action(Shelf, :build)
+      injected = Enum.filter(action.arguments, &(&1.name in [:specified_by, :features, :characteristics]))
+      assert Enum.all?(injected, &(&1.public? == false))
+    end
+
+    test "characteristic/1 returns the named characteristic" do
+      char = Shelf.characteristic(:shelves)
+      assert char.name == :shelves
+      assert char.value_type == {:array, Diffo.Test.ShelfValue}
+    end
+
+    test "characteristic/1 returns nil for unknown name" do
+      assert Shelf.characteristic(:nonexistent) == nil
+    end
+
+    test "feature/1 returns the named feature" do
+      feature = Shelf.feature(:spectralManagement)
+      assert feature.name == :spectralManagement
+      assert feature.is_enabled? == true
+    end
+
+    test "feature/1 returns nil for unknown name" do
+      assert Shelf.feature(:nonexistent) == nil
+    end
+
+    test "feature_characteristic/2 returns the named characteristic within a feature" do
+      char = Shelf.feature_characteristic(:spectralManagement, :deploymentClass)
+      assert char.name == :deploymentClass
+    end
+
+    test "feature_characteristic/2 returns nil for unknown feature" do
+      assert Shelf.feature_characteristic(:nonexistent, :deploymentClass) == nil
+    end
+
+    test "feature_characteristic/2 returns nil for unknown characteristic" do
+      assert Shelf.feature_characteristic(:spectralManagement, :nonexistent) == nil
+    end
+
+    test "party/1 returns the named party declaration by role" do
+      p = Shelf.party(:facilitator)
+      assert p.role == :facilitator
+      assert p.multiple == false
+    end
+
+    test "party/1 returns nil for unknown role" do
+      assert Shelf.party(:nonexistent) == nil
+    end
+  end
+end
diff --git a/test/instance_extension/verifier_test.exs b/test/instance_extension/verifier_test.exs
new file mode 100644
index 0000000..d679b70
--- /dev/null
+++ b/test/instance_extension/verifier_test.exs
@@ -0,0 +1,367 @@
+# SPDX-FileCopyrightText: 2025 diffo contributors <https://github.com/diffo-dev/diffo/graphs.contributors>
+#
+# SPDX-License-Identifier: MIT
+
+defmodule Diffo.InstanceExtension.VerifierTest do
+  @moduledoc false
+  use ExUnit.Case, async: false
+  alias Diffo.Test.Util
+
+  describe "specification verifier" do
+    test "invalid UUID4 in specification id warns DslError on compilation" do
+      Util.assert_compile_time_warning(
+        Spark.Error.DslError,
+        "specification: id must be a valid UUID4",
+        fn ->
+          defmodule InvalidSpecId do
+            alias Diffo.Provider.BaseInstance
+            use Ash.Resource, fragments: [BaseInstance], domain: Diffo.Test.Servo
+
+            resource do
+              description "resource with invalid spec id"
+            end
+
+            structure do
+              specification do
+                id "ef016d85-9dbd-429c-04da-1df56cc7dda5"
+                name "invalid"
+              end
+            end
+          end
+        end
+      )
+    end
+  end
+
+  describe "characteristics verifier" do
+    test "duplicate characteristic name warns DslError on compilation" do
+      Util.assert_compile_time_warning(
+        Spark.Error.DslError,
+        "characteristics: name :foo is declared more than once",
+        fn ->
+          defmodule DuplicateCharName do
+            alias Diffo.Provider.BaseInstance
+            use Ash.Resource, fragments: [BaseInstance], domain: Diffo.Test.Servo
+
+            resource do
+              description "resource with duplicate characteristic name"
+            end
+
+            structure do
+              specification do
+                id "cd29956f-6c68-44cc-bf54-705eb8d2f754"
+                name "invalid"
+              end
+
+              characteristics do
+                characteristic :foo, Diffo.Test.ShelfValue
+                characteristic :foo, Diffo.Test.ShelfValue
+              end
+            end
+          end
+        end
+      )
+    end
+
+    test "non-existent value_type module warns DslError on compilation" do
+      Util.assert_compile_time_warning(
+        Spark.Error.DslError,
+        "characteristics: value_type NonExistent.CharValue does not exist",
+        fn ->
+          defmodule InvalidCharValueType do
+            alias Diffo.Provider.BaseInstance
+            use Ash.Resource, fragments: [BaseInstance], domain: Diffo.Test.Servo
+
+            resource do
+              description "resource with non-existent characteristic value_type"
+            end
+
+            structure do
+              specification do
+                id "cd29956f-6c68-44cc-bf54-705eb8d2f754"
+                name "invalid"
+              end
+
+              characteristics do
+                characteristic :foo, NonExistent.CharValue
+              end
+            end
+          end
+        end
+      )
+    end
+
+    test "non-existent array value_type module warns DslError on compilation" do
+      Util.assert_compile_time_warning(
+        Spark.Error.DslError,
+        "characteristics: value_type NonExistent.ArrayValue does not exist",
+        fn ->
+          defmodule InvalidArrayCharValueType do
+            alias Diffo.Provider.BaseInstance
+            use Ash.Resource, fragments: [BaseInstance], domain: Diffo.Test.Servo
+
+            resource do
+              description "resource with non-existent array characteristic value_type"
+            end
+
+            structure do
+              specification do
+                id "cd29956f-6c68-44cc-bf54-705eb8d2f754"
+                name "invalid"
+              end
+
+              characteristics do
+                characteristic :bar, {:array, NonExistent.ArrayValue}
+              end
+            end
+          end
+        end
+      )
+    end
+  end
+
+  describe "features verifier" do
+    test "duplicate feature name warns DslError on compilation" do
+      Util.assert_compile_time_warning(
+        Spark.Error.DslError,
+        "features: name :my_feature is declared more than once",
+        fn ->
+          defmodule DuplicateFeatureName do
+            alias Diffo.Provider.BaseInstance
+            use Ash.Resource, fragments: [BaseInstance], domain: Diffo.Test.Servo
+
+            resource do
+              description "resource with duplicate feature names"
+            end
+
+            structure do
+              specification do
+                id "cd29956f-6c68-44cc-bf54-705eb8d2f754"
+                name "invalid"
+              end
+
+              features do
+                feature :my_feature do
+                end
+
+                feature :my_feature do
+                end
+              end
+            end
+          end
+        end
+      )
+    end
+
+    test "duplicate feature characteristic name warns DslError on compilation" do
+      Util.assert_compile_time_warning(
+        Spark.Error.DslError,
+        "features: characteristic name :baz is declared more than once in :my_feature",
+        fn ->
+          defmodule DuplicateFeatureCharName do
+            alias Diffo.Provider.BaseInstance
+            use Ash.Resource, fragments: [BaseInstance], domain: Diffo.Test.Servo
+
+            resource do
+              description "resource with duplicate feature characteristic names"
+            end
+
+            structure do
+              specification do
+                id "cd29956f-6c68-44cc-bf54-705eb8d2f754"
+                name "invalid"
+              end
+
+              features do
+                feature :my_feature do
+                  characteristic :baz, Diffo.Test.ShelfValue
+                  characteristic :baz, Diffo.Test.ShelfValue
+                end
+              end
+            end
+          end
+        end
+      )
+    end
+
+    test "non-existent feature characteristic value_type warns DslError on compilation" do
+      Util.assert_compile_time_warning(
+        Spark.Error.DslError,
+        "features: characteristic value_type NonExistent.FeatureValue does not exist",
+        fn ->
+          defmodule InvalidFeatureCharValueType do
+            alias Diffo.Provider.BaseInstance
+            use Ash.Resource, fragments: [BaseInstance], domain: Diffo.Test.Servo
+
+            resource do
+              description "resource with non-existent feature characteristic value_type"
+            end
+
+            structure do
+              specification do
+                id "cd29956f-6c68-44cc-bf54-705eb8d2f754"
+                name "invalid"
+              end
+
+              features do
+                feature :my_feature do
+                  characteristic :baz, NonExistent.FeatureValue
+                end
+              end
+            end
+          end
+        end
+      )
+    end
+  end
+
+  describe "parties verifier" do
+    test "duplicate party role names warns DslError on compilation" do
+      Util.assert_compile_time_warning(
+        Spark.Error.DslError,
+        "parties: role :operator is declared more than once",
+        fn ->
+          defmodule DuplicatePartyRole do
+            alias Diffo.Provider.BaseInstance
+            alias Diffo.Test.Shelf
+            use Ash.Resource, fragments: [BaseInstance], domain: Diffo.Test.Servo
+
+            resource do
+              description "resource with duplicate party roles"
+            end
+
+            structure do
+              specification do
+                id "cd29956f-6c68-44cc-bf54-705eb8d2f754"
+                name "invalid"
+              end
+
+              parties do
+                party :operator, Shelf
+                party :operator, Shelf
+              end
+            end
+          end
+        end
+      )
+    end
+
+    test "non-existent party_type module warns DslError on compilation" do
+      Util.assert_compile_time_warning(
+        Spark.Error.DslError,
+        "parties: party_type NonExistent.PartyModule does not exist",
+        fn ->
+          defmodule InvalidPartyType do
+            alias Diffo.Provider.BaseInstance
+            use Ash.Resource, fragments: [BaseInstance], domain: Diffo.Test.Servo
+
+            resource do
+              description "resource with non-existent party_type"
+            end
+
+            structure do
+              specification do
+                id "cd29956f-6c68-44cc-bf54-705eb8d2f754"
+                name "invalid"
+              end
+
+              parties do
+                party :operator, NonExistent.PartyModule
+              end
+            end
+          end
+        end
+      )
+    end
+
+    test "party_type not extending BaseParty warns DslError on compilation" do
+      Util.assert_compile_time_warning(
+        Spark.Error.DslError,
+        "parties: party_type Diffo.Test.Shelf does not extend BaseParty",
+        fn ->
+          defmodule InvalidPartyBaseType do
+            alias Diffo.Provider.BaseInstance
+            use Ash.Resource, fragments: [BaseInstance], domain: Diffo.Test.Servo
+
+            resource do
+              description "resource with party_type that is not a BaseParty"
+            end
+
+            structure do
+              specification do
+                id "cd29956f-6c68-44cc-bf54-705eb8d2f754"
+                name "invalid"
+              end
+
+              parties do
+                party :operator, Diffo.Test.Shelf
+              end
+            end
+          end
+        end
+      )
+    end
+  end
+
+  describe "behaviour verifier" do
+    test "undeclared create action name warns DslError on compilation" do
+      Util.assert_compile_time_warning(
+        Spark.Error.DslError,
+        "behaviour: create :nonexistent does not exist as a create action on this resource",
+        fn ->
+          defmodule BehaviourMissingCreate do
+            alias Diffo.Provider.BaseInstance
+            use Ash.Resource, fragments: [BaseInstance], domain: Diffo.Test.Servo
+
+            resource do
+              description "resource with behaviour referencing a missing create action"
+            end
+
+            structure do
+              specification do
+                id "cd29956f-6c68-44cc-bf54-705eb8d2f754"
+                name "invalid"
+              end
+            end
+
+            behaviour do
+              actions do
+                create :nonexistent
+              end
+            end
+          end
+        end
+      )
+    end
+
+    test "undeclared update action name warns DslError on compilation" do
+      Util.assert_compile_time_warning(
+        Spark.Error.DslError,
+        "behaviour: update :nonexistent does not exist as an update action on this resource",
+        fn ->
+          defmodule BehaviourMissingUpdate do
+            alias Diffo.Provider.BaseInstance
+            use Ash.Resource, fragments: [BaseInstance], domain: Diffo.Test.Servo
+
+            resource do
+              description "resource with behaviour referencing a missing update action"
+            end
+
+            structure do
+              specification do
+                id "cd29956f-6c68-44cc-bf54-705eb8d2f754"
+                name "invalid"
+              end
+            end
+
+            behaviour do
+              actions do
+                update :nonexistent
+              end
+            end
+          end
+        end
+      )
+    end
+  end
+end
diff --git a/test/support/resource/card.ex b/test/support/resource/card.ex
index 4056a1b..9792b8e 100644
--- a/test/support/resource/card.ex
+++ b/test/support/resource/card.ex
@@ -11,7 +11,6 @@ defmodule Diffo.Test.Card do
   alias Diffo.Provider.BaseInstance
   alias Diffo.Provider.Instance.Relationship
   alias Diffo.Provider.Instance.Characteristic
-  alias Diffo.Provider.Instance.ActionHelper
   alias Diffo.Provider.Assigner
   alias Diffo.Provider.Assignment
   alias Diffo.Provider.AssignableValue
@@ -27,40 +26,36 @@ defmodule Diffo.Test.Card do
     plural_name :Cards
   end
 
-  specification do
-    id "cd29956f-6c68-44cc-bf54-705eb8d2f754"
-    name "card"
-    type :resourceSpecification
-    description "A Card Resource Instance"
-    category "Network Resource"
+  structure do
+    specification do
+      id "cd29956f-6c68-44cc-bf54-705eb8d2f754"
+      name "card"
+      type :resourceSpecification
+      description "A Card Resource Instance"
+      category "Network Resource"
+    end
+
+    characteristics do
+      characteristic :card, CardValue
+      characteristic :ports, AssignableValue
+    end
   end
 
-  characteristics do
-    characteristic :card, CardValue
-    characteristic :ports, AssignableValue
+  behaviour do
+    actions do
+      create :build
+    end
   end
 
   actions do
     create :build do
       description "creates a new Card resource instance for build"
       accept [:id, :name, :type, :which]
-      argument :specified_by, :uuid, public?: false
       argument :relationships, {:array, :struct}
-      argument :features, {:array, :uuid}, public?: false
-      argument :characteristics, {:array, :uuid}, public?: false
       argument :places, {:array, :struct}
       argument :parties, {:array, :struct}
 
       change set_attribute(:type, :resource)
-
-      change before_action(fn changeset, _context ->
-               ActionHelper.build_before(changeset)
-             end)
-
-      change after_action(fn changeset, result, _context ->
-               ActionHelper.build_after(changeset, result, Servo, :get_card_by_id)
-             end)
-
       change load [:href]
       upsert? false
     end
diff --git a/test/support/resource/invalid/invalid_characteristic.ex b/test/support/resource/invalid/invalid_characteristic.ex
index 52b0ef6..2053dba 100644
--- a/test/support/resource/invalid/invalid_characteristic.ex
+++ b/test/support/resource/invalid/invalid_characteristic.ex
@@ -10,55 +10,33 @@ defmodule Diffo.Test.InvalidCharacteristic do
   """
 
   alias Diffo.Provider.BaseInstance
-  alias Diffo.Provider.Instance.ActionHelper
-
-  alias Diffo.Test.Servo
 
   use Ash.Resource,
     fragments: [BaseInstance],
-    domain: Servo
+    domain: Diffo.Test.Servo
 
   resource do
     description "Ash Resource with an invalid characteristic"
   end
 
-  specification do
-    id "3caf29b9-0b91-4b8f-8568-2960131b1feb"
-    name "invalidCharacteristic"
-    type :resourceSpecification
-    category "Network Resource"
-  end
+  structure do
+    specification do
+      id "3caf29b9-0b91-4b8f-8568-2960131b1feb"
+      name "invalidCharacteristic"
+      type :resourceSpecification
+      category "Network Resource"
+    end
 
-  characteristics do
-    characteristic :invalid, InvalidValue
+    characteristics do
+      characteristic :invalid, InvalidValue
+    end
   end
 
   actions do
     create :build do
       description "creates a new InvalidCharacteristic resource instance for build"
       accept [:id, :name, :type, :which]
-      argument :specified_by, :uuid, public?: false
-      argument :relationships, {:array, :struct}
-      argument :features, {:array, :uuid}, public?: false
-      argument :characteristics, {:array, :uuid}, public?: false
-      argument :places, {:array, :struct}
-      argument :parties, {:array, :struct}
-
       change set_attribute(:type, :resource)
-
-      change before_action(fn changeset, _context ->
-               ActionHelper.build_before(changeset)
-             end)
-
-      change after_action(fn changeset, result, _context ->
-               ActionHelper.build_after(
-                 changeset,
-                 result,
-                 Servo,
-                 :get_invalid_characteristic_by_id
-               )
-             end)
-
       change load [:href]
       upsert? false
     end
diff --git a/test/support/resource/invalid/invalid_feature_characteristic.ex b/test/support/resource/invalid/invalid_feature_characteristic.ex
index 2d8f791..143b717 100644
--- a/test/support/resource/invalid/invalid_feature_characteristic.ex
+++ b/test/support/resource/invalid/invalid_feature_characteristic.ex
@@ -10,29 +10,28 @@ defmodule Diffo.Test.InvalidFeatureCharacteristic do
   """
 
   alias Diffo.Provider.BaseInstance
-  alias Diffo.Provider.Instance.ActionHelper
-
-  alias Diffo.Test.Servo
 
   use Ash.Resource,
     fragments: [BaseInstance],
-    domain: Servo
+    domain: Diffo.Test.Servo
 
   resource do
     description "Ash Resource with an invalid feature characteristic"
   end
 
-  specification do
-    id "1f2402ca-82da-428e-a58b-5405a5431386"
-    name "invalidFeatureCharacteristic"
-    type :resourceSpecification
-    category "Network Resource"
-  end
+  structure do
+    specification do
+      id "1f2402ca-82da-428e-a58b-5405a5431386"
+      name "invalidFeatureCharacteristic"
+      type :resourceSpecification
+      category "Network Resource"
+    end
 
-  features do
-    feature :invalid_feature_characteristic do
-      is_enabled? true
-      characteristic :invalid, InvalidValue
+    features do
+      feature :invalid_feature_characteristic do
+        is_enabled? true
+        characteristic :invalid, InvalidValue
+      end
     end
   end
 
@@ -40,28 +39,7 @@ defmodule Diffo.Test.InvalidFeatureCharacteristic do
     create :build do
       description "creates a new InvalidFeatureCharacteristic resource instance for build"
       accept [:id, :name, :type, :which]
-      argument :specified_by, :uuid, public?: false
-      argument :relationships, {:array, :struct}
-      argument :features, {:array, :uuid}, public?: false
-      argument :characteristics, {:array, :uuid}, public?: false
-      argument :places, {:array, :struct}
-      argument :parties, {:array, :struct}
-
       change set_attribute(:type, :resource)
-
-      change before_action(fn changeset, _context ->
-               ActionHelper.build_before(changeset)
-             end)
-
-      change after_action(fn changeset, result, _context ->
-               ActionHelper.build_after(
-                 changeset,
-                 result,
-                 Servo,
-                 :get_invalid_feature_characteristic_by_id
-               )
-             end)
-
       change load [:href]
       upsert? false
     end
diff --git a/test/support/resource/invalid/invalid_specification.ex b/test/support/resource/invalid/invalid_specification.ex
index 4591912..b409619 100644
--- a/test/support/resource/invalid/invalid_specification.ex
+++ b/test/support/resource/invalid/invalid_specification.ex
@@ -10,51 +10,29 @@ defmodule Diffo.Test.InvalidSpecification do
   """
 
   alias Diffo.Provider.BaseInstance
-  alias Diffo.Provider.Instance.ActionHelper
-
-  alias Diffo.Test.Servo
 
   use Ash.Resource,
     fragments: [BaseInstance],
-    domain: Servo
+    domain: Diffo.Test.Servo
 
   resource do
     description "Ash Resource with an invalid specification"
   end
 
-  specification do
-    id "ef016d85-9dbd-429c-04da-1df56cc7dda5"
-    name "invalidSpecification"
-    type :resourceSpecification
-    category "Network Resource"
+  structure do
+    specification do
+      id "ef016d85-9dbd-429c-04da-1df56cc7dda5"
+      name "invalidSpecification"
+      type :resourceSpecification
+      category "Network Resource"
+    end
   end
 
   actions do
     create :build do
       description "creates a new InvalidSpecification resource instance for build"
       accept [:id, :name, :type, :which]
-      argument :specified_by, :uuid, public?: false
-      argument :relationships, {:array, :struct}
-      argument :features, {:array, :uuid}, public?: false
-      argument :characteristics, {:array, :uuid}, public?: false
-      argument :places, {:array, :struct}
-      argument :parties, {:array, :struct}
-
       change set_attribute(:type, :resource)
-
-      change before_action(fn changeset, _context ->
-               ActionHelper.build_before(changeset)
-             end)
-
-      change after_action(fn changeset, result, _context ->
-               ActionHelper.build_after(
-                 changeset,
-                 result,
-                 Servo,
-                 :get_invalid_specification_by_id
-               )
-             end)
-
       change load [:href]
       upsert? false
     end
diff --git a/test/support/resource/shelf.ex b/test/support/resource/shelf.ex
index 71350ce..b9022b3 100644
--- a/test/support/resource/shelf.ex
+++ b/test/support/resource/shelf.ex
@@ -12,7 +12,6 @@ defmodule Diffo.Test.Shelf do
   alias Diffo.Provider.BaseInstance
   alias Diffo.Provider.Instance.Relationship
   alias Diffo.Provider.Instance.Characteristic
-  alias Diffo.Provider.Instance.ActionHelper
   alias Diffo.Provider.Assigner
   alias Diffo.Provider.Assignment
   alias Diffo.Provider.AssignableValue
@@ -30,57 +29,53 @@ defmodule Diffo.Test.Shelf do
     plural_name :Shelves
   end
 
-  specification do
-    id "ef016d85-9dbd-429c-84da-1df56cc7dda5"
-    name "shelf"
-    type :resourceSpecification
-    description "A Shelf Resource Instance which contain cards"
-    category "Network Resource"
-  end
+  structure do
+    specification do
+      id "ef016d85-9dbd-429c-84da-1df56cc7dda5"
+      name "shelf"
+      type :resourceSpecification
+      description "A Shelf Resource Instance which contain cards"
+      category "Network Resource"
+    end
 
-  features do
-    feature :spectralManagement do
-      is_enabled? true
-      characteristic :deploymentClass, DeploymentClassValue
-      characteristic :deploymentClasses, {:array, DeploymentClassValue}
+    features do
+      feature :spectralManagement do
+        is_enabled? true
+        characteristic :deploymentClass, DeploymentClassValue
+        characteristic :deploymentClasses, {:array, DeploymentClassValue}
+      end
     end
-  end
 
-  characteristics do
-    characteristic :shelf, ShelfValue
-    characteristic :slots, AssignableValue
-    characteristic :shelves, {:array, ShelfValue}
+    characteristics do
+      characteristic :shelf, ShelfValue
+      characteristic :slots, AssignableValue
+      characteristic :shelves, {:array, ShelfValue}
+    end
+
+    parties do
+      party :facilitator, Diffo.Test.Organization
+      party :overseer, Diffo.Test.Person
+      party :provider, Diffo.Test.Organization, reference: true
+      party :manager, Diffo.Test.Organization, calculate: :manager_calc
+      parties :installer, Diffo.Test.Person, constraints: [min: 1, max: 3]
+    end
   end
 
-  parties do
-    party :facilitator, Diffo.Test.Organization
-    party :overseer, Diffo.Test.Person
-    party :provider, Diffo.Test.Organization, reference: true
-    party :manager, Diffo.Test.Organization, calculate: :manager_calc
-    parties :installer, Diffo.Test.Person, constraints: [min: 1, max: 3]
+  behaviour do
+    actions do
+      create :build
+    end
   end
 
   actions do
     create :build do
       description "creates a new Shelf resource instance for build"
       accept [:id, :name, :type, :which]
-      argument :specified_by, :uuid, public?: false
       argument :relationships, {:array, :struct}
-      argument :features, {:array, :uuid}, public?: false
-      argument :characteristics, {:array, :uuid}, public?: false
       argument :places, {:array, :struct}
       argument :parties, {:array, :struct}
 
       change set_attribute(:type, :resource)
-
-      change before_action(fn changeset, _context ->
-               ActionHelper.build_before(changeset)
-             end)
-
-      change after_action(fn changeset, result, _context ->
-               ActionHelper.build_after(changeset, result, Servo, :get_shelf_by_id)
-             end)
-
       change load [:href]
       upsert? false
     end
diff --git a/test/support/util.ex b/test/support/util.ex
new file mode 100644
index 0000000..0b01056
--- /dev/null
+++ b/test/support/util.ex
@@ -0,0 +1,15 @@
+# SPDX-FileCopyrightText: 2025 diffo contributors <https://github.com/diffo-dev/diffo/graphs.contributors>
+#
+# SPDX-License-Identifier: MIT
+
+defmodule Diffo.Test.Util do
+  @moduledoc false
+  use ExUnit.Case
+  import ExUnit.CaptureIO
+
+  def assert_compile_time_warning(module, message, fun) when is_bitstring(message) do
+    output = capture_io(:stderr, fun)
+    assert output =~ String.trim_leading("#{module}", "Elixir.")
+    assert output =~ message
+  end
+end