diff --git a/.speakeasy/workflow.yaml b/.speakeasy/workflow.yaml
index 6e3084fd..1586eb0e 100644
--- a/.speakeasy/workflow.yaml
+++ b/.speakeasy/workflow.yaml
@@ -12,6 +12,7 @@ sources:
             - location: overlays/strip-headers-overlay.yaml
             - location: overlays/client-modifications-overlay.yaml
             - location: overlays/indexing-modifications-overlay.yaml
+            - location: overlays/custom-metadata-modifications-overlay.yaml
             - location: overlays/agent-modifications-overlay.yaml
             - location: overlays/admin-modifications-overlay.yaml
         output: overlayed_specs/glean-merged-spec.yaml
@@ -58,5 +59,6 @@ sources:
             - location: overlays/info-name-overlay.yaml
             - location: overlays/strip-headers-overlay.yaml
             - location: overlays/indexing-modifications-overlay.yaml
+            - location: overlays/custom-metadata-modifications-overlay.yaml
         output: overlayed_specs/glean-indexing-api-specs.yaml
 targets: {}
diff --git a/overlays/custom-metadata-modifications-overlay.yaml b/overlays/custom-metadata-modifications-overlay.yaml
new file mode 100644
index 00000000..8535344d
--- /dev/null
+++ b/overlays/custom-metadata-modifications-overlay.yaml
@@ -0,0 +1,69 @@
+overlay: 1.0.0
+x-speakeasy-jsonpath: rfc9535
+info:
+  title: Speakeasy Modifications - Custom Metadata
+  version: 0.0.1
+
+actions:
+  # Custom Metadata - SDK grouping and method names
+  - target: $["paths"]["/rest/api/index/document/{docId}/custom-metadata/{groupName}"]["put"]
+    update:
+      x-speakeasy-name-override: upsert
+      x-speakeasy-group: indexing.customMetadata
+
+  - target: $["paths"]["/rest/api/index/document/{docId}/custom-metadata/{groupName}"]["delete"]
+    update:
+      x-speakeasy-name-override: delete
+      x-speakeasy-group: indexing.customMetadata
+
+  - target: $["paths"]["/rest/api/index/custom-metadata/schema/{groupName}"]["get"]
+    update:
+      x-speakeasy-name-override: getSchema
+      x-speakeasy-group: indexing.customMetadata
+
+  - target: $["paths"]["/rest/api/index/custom-metadata/schema/{groupName}"]["put"]
+    update:
+      x-speakeasy-name-override: upsertSchema
+      x-speakeasy-group: indexing.customMetadata
+
+  - target: $["paths"]["/rest/api/index/custom-metadata/schema/{groupName}"]["delete"]
+    update:
+      x-speakeasy-name-override: deleteSchema
+      x-speakeasy-group: indexing.customMetadata
+
+  # Introduce a Custom Metadata-specific PropertyDefinition schema that exposes only
+  # the fields applicable to Custom Metadata. The shared PropertyDefinition schema
+  # (used by the Datasource / Custom Properties API) carries fields like displayLabel,
+  # displayLabelPlural, uiOptions, hideUiFacet, uiFacetOrder, and group that are not
+  # relevant to Custom Metadata. We cannot strip those fields from PropertyDefinition
+  # itself without affecting the Indexing API surface, so we create a
+  # narrower schema scoped to Custom Metadata and re-point CustomMetadataSchema to it.
+  - target: $["components"]["schemas"]
+    update:
+      CustomMetadataPropertyDefinition:
+        type: object
+        description: The definition for a key within a Custom Metadata schema. Only the fields applicable to Custom Metadata are exposed.
+        properties:
+          name:
+            type: string
+            description: The name of the metadata key.
+          propertyType:
+            type: string
+            enum:
+              - TEXT
+              - PICKLIST
+              - TEXTLIST
+              - MULTIPICKLIST
+            description: The type of metadata key. This governs the search and faceting behavior.
+          skipIndexing:
+            type: boolean
+            description: If true then the property will not be indexed for retrieval and ranking.
+        required:
+          - name
+          - propertyType
+
+  # Re-point CustomMetadataSchema.metadataKeys to the narrower schema above.
+  - target: $["components"]["schemas"]["CustomMetadataSchema"]["properties"]["metadataKeys"]
+    update:
+      items:
+        $ref: '#/components/schemas/CustomMetadataPropertyDefinition'
diff --git a/tests/post_transform_smoke.test.js b/tests/post_transform_smoke.test.js
index ae27ef52..0ef3439f 100644
--- a/tests/post_transform_smoke.test.js
+++ b/tests/post_transform_smoke.test.js
@@ -55,7 +55,12 @@ describe('Post-transformation smoke tests', () => {
 
     expect(paths.length).toBeGreaterThan(0);
 
-    const allowedPrefixes = ['/rest/api/v1', '/api/index/v1', '/api/'];
+    const allowedPrefixes = [
+      '/rest/api/v1',
+      '/api/index/v1',
+      '/api/',
+      '/rest/api/index/',
+    ];
     const hasUnexpected = paths.some(
       (p) => !allowedPrefixes.some((prefix) => p.startsWith(prefix)),
     );
diff --git a/tests/source-spec-transformer.test.js b/tests/source-spec-transformer.test.js
index 652f59c0..a0b3d74b 100644
--- a/tests/source-spec-transformer.test.js
+++ b/tests/source-spec-transformer.test.js
@@ -89,8 +89,26 @@ describe('OpenAPI YAML Transformer', () => {
 
     expect(transformedPaths.length).toBe(originalPaths.length);
 
+    // A path may declare its own `servers:` block; in that case the transformer
+    // prefixes the path with that path-level basePath rather than the global one.
+    const expectedBasePathFor = (pathValue) => {
+      const pathServers = pathValue?.servers;
+      if (Array.isArray(pathServers) && pathServers.length > 0) {
+        const candidate = extractBasePath(pathServers[0].url ?? '');
+        if (candidate) return candidate;
+      }
+      return originalBasePath;
+    };
+
+    const allExpectedBasePaths = new Set();
+
     for (const originalPath of originalPaths) {
-      const expectedTransformedPath = `${originalBasePath}${originalPath}`;
+      const expectedBasePath = expectedBasePathFor(
+        originalSpec.paths[originalPath],
+      );
+      allExpectedBasePaths.add(expectedBasePath);
+
+      const expectedTransformedPath = `${expectedBasePath}${originalPath}`;
       expect(transformedSpec.paths).toHaveProperty(expectedTransformedPath);
 
       const originalOperations = originalSpec.paths[originalPath];
@@ -103,7 +121,10 @@ describe('OpenAPI YAML Transformer', () => {
     }
 
     for (const path of transformedPaths) {
-      expect(path.startsWith(originalBasePath)).toBe(true);
+      const matchesSomeBasePath = [...allExpectedBasePaths].some((prefix) =>
+        path.startsWith(prefix),
+      );
+      expect(matchesSomeBasePath).toBe(true);
     }
 
     if (