diff --git a/openspec/specs/settings-service/spec.md b/openspec/specs/settings-service/spec.md
index d410e889..f3332084 100644
--- a/openspec/specs/settings-service/spec.md
+++ b/openspec/specs/settings-service/spec.md
@@ -142,3 +142,25 @@ The service MUST call `importFromApp` from a single call site with the same, sta
 - AND WHEN the true fix is determined to belong in OpenRegister rather than this app
 - THEN an issue MUST be filed against the owning repository documenting the mechanism, and referenced from this app's code and docs
 
+### Requirement: The system SHALL merge ADR-037 register fragments so disjoint fragments never collide (REQ-007)
+
+`SettingsService::deepMergeConfig()` is the single merge primitive that folds every `register.d/*.json` fragment onto the monolith register. Its contract MUST be: nested maps merge key-by-key so that fragments touching *disjoint* keys all survive the merge; list values concatenate; scalar values from the overlay overwrite the base. This is what allows concurrent OpenSpec changes to each ship their own fragment without either one's schemas or paths being lost — the property ADR-037 exists to provide. The one deliberate exception is the `authorization` subtree, which replaces rather than concatenates; that carve-out and its rationale are specified under `catalog-ratings`, and this requirement MUST NOT be read as overriding it.
+
+#### Scenario: Disjoint fragments union their schemas and paths
+
+- GIVEN a base register declaring schema `Existing` and path `/existing`
+- AND a fragment adding schema `AlphaComponent` and path `/alpha`
+- AND a second fragment adding schema `BetaService` and path `/beta`
+- WHEN the fragments are merged onto the base in sequence
+- THEN all three schemas MUST be present under `components.schemas`
+- AND all three paths MUST be present under `paths`
+- AND no earlier fragment's contribution may be dropped by a later one
+
+#### Scenario: Lists concatenate and scalars overwrite
+
+- GIVEN a base with `required: ["a", "b"]` and `info.version: "0.1.0"`
+- AND an overlay with `required: ["c"]` and `info.version: "0.2.0"`
+- WHEN the overlay is merged onto the base
+- THEN `required` MUST be `["a", "b", "c"]`
+- AND `info.version` MUST be `"0.2.0"`
+
diff --git a/tests/Unit/Service/RegisterFragmentMergeTest.php b/tests/Unit/Service/RegisterFragmentMergeTest.php
index 5f9b31bf..c47b9667 100644
--- a/tests/Unit/Service/RegisterFragmentMergeTest.php
+++ b/tests/Unit/Service/RegisterFragmentMergeTest.php
@@ -12,7 +12,7 @@
  *
  * @link https://conduction.nl
  *
- * @spec openspec/changes/modular-register-manifest-fragments/specs/modular-config/spec.md
+ * @spec openspec/specs/settings-service/spec.md#requirement-the-system-shall-merge-adr-037-register-fragments-so-disjoint-fragments-never-collide-req-007
  */
 
 declare(strict_types=1);
@@ -48,6 +48,7 @@ private function merge(array $base, array $overlay): array
      * Two fragments adding disjoint OpenAPI schemas/paths union by key.
      *
      * @return void
+     * @spec   openspec/specs/settings-service/spec.md#scenario-disjoint-fragments-union-their-schemas-and-paths
      */
     public function testDisjointFragmentsUnionSchemasAndPaths(): void
     {
@@ -84,6 +85,7 @@ public function testDisjointFragmentsUnionSchemasAndPaths(): void
      * List arrays are concatenated; scalars overwrite.
      *
      * @return void
+     * @spec   openspec/specs/settings-service/spec.md#scenario-lists-concatenate-and-scalars-overwrite
      */
     public function testListsConcatenateAndScalarsOverwrite(): void
     {
diff --git a/tests/Unit/Service/SbomRegisterShapeTest.php b/tests/Unit/Service/SbomRegisterShapeTest.php
index 7d3d6689..d8cffded 100644
--- a/tests/Unit/Service/SbomRegisterShapeTest.php
+++ b/tests/Unit/Service/SbomRegisterShapeTest.php
@@ -87,7 +87,7 @@ private function schema(string $slug): array
      * actually writes them to and the status endpoint reads them from.
      *
      * @return void
-     * @spec   openspec/specs/sbom-import/spec.md#requirement-a-successful-import-records-provenance-on-the-version
+     * @spec   openspec/specs/sbom-import/spec.md#scenario-a-successful-import-records-provenance-on-the-version
      */
     public function testModuleVersieCarriesSbomProvenance(): void
     {
@@ -117,7 +117,7 @@ public function testModuleVersieCarriesSbomProvenance(): void
      * that shipped the silent-drop defect.
      *
      * @return void
-     * @spec   openspec/specs/sbom-import/spec.md#requirement-a-successful-import-records-provenance-on-the-version
+     * @spec   openspec/specs/sbom-import/spec.md#scenario-a-successful-import-records-provenance-on-the-version
      */
     public function testOrganisatieDoesNotCarrySbomProvenance(): void
     {
@@ -136,7 +136,7 @@ public function testOrganisatieDoesNotCarrySbomProvenance(): void
      * rows without these fields stays non-destructive.
      *
      * @return void
-     * @spec   openspec/specs/sbom-import/spec.md#requirement-existing-versions-are-unaffected-by-the-schema-addition
+     * @spec   openspec/specs/sbom-import/spec.md#scenario-existing-versions-are-unaffected-by-the-schema-addition
      */
     public function testSbomProvenanceIsOptional(): void
     {
@@ -155,7 +155,7 @@ public function testSbomProvenanceIsOptional(): void
      * voorzieningen register, so imported components have a home table.
      *
      * @return void
-     * @spec   openspec/specs/sbom-import/spec.md#requirement-a-parsed-component-persists-with-its-moduleversie-relation
+     * @spec   openspec/specs/sbom-import/spec.md#scenario-a-parsed-component-persists-with-its-moduleversie-relation
      */
     public function testSbomComponentIsRegisteredInVoorzieningen(): void
     {