From 9482e71546566b31a9469228e48fb9658189f291 Mon Sep 17 00:00:00 2001
From: Daniel O'Grady <daniel.o-grady@sap.com>
Date: Thu, 3 Sep 2026 09:59:03 +0200
Subject: [PATCH] feat: support @openapi.type and @openapi.default on custom
 parameters

---
 CHANGELOG.md                                  |  1 +
 lib/compile/csdl2openapi.js                   |  3 ++-
 test/lib/compile/data/custom-parameters.json  | 13 +++++++++++++
 .../data/custom-parameters.openapi3.json      | 19 +++++++++++++++++++
 4 files changed, 35 insertions(+), 1 deletion(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index c7be42e..50068e9 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,6 +7,7 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/).
 ## [Unreleased]
 
 ### Added
+- Support `@openapi.type` and `@openapi.default` annotations on `CustomParameter` records (`CustomHeaders`/`CustomQueryOptions`) to emit the correct schema type and default value instead of always defaulting to `schema.type: "string"`
 ### Changed
 ### Deprecated
 ### Removed
diff --git a/lib/compile/csdl2openapi.js b/lib/compile/csdl2openapi.js
index 2fddefd..c1dc213 100644
--- a/lib/compile/csdl2openapi.js
+++ b/lib/compile/csdl2openapi.js
@@ -844,7 +844,8 @@ module.exports.csdl2openapi = function (
             required: custom.Required || false,
             ...(custom.Description && { description: custom.Description }),
             schema: {
-                type: "string",
+                type: custom['@openapi.type'] || "string",
+                ...(custom['@openapi.default'] !== undefined && { default: custom['@openapi.default'] }),
                 ...(custom.DocumentationURL && {
                     externalDocs: { url: custom.DocumentationURL },
                 }),
diff --git a/test/lib/compile/data/custom-parameters.json b/test/lib/compile/data/custom-parameters.json
index b6792fd..01fb608 100644
--- a/test/lib/compile/data/custom-parameters.json
+++ b/test/lib/compile/data/custom-parameters.json
@@ -194,6 +194,19 @@
                                     "Value": "example"
                                 }
                             ]
+                        },
+                        {
+                            "Name": "custom-insert-typed",
+                            "Description": "Custom Header with explicit boolean type and default",
+                            "Required": false,
+                            "@openapi.type": "boolean",
+                            "@openapi.default": true
+                        },
+                        {
+                            "Name": "custom-insert-integer",
+                            "Description": "Custom Header with explicit integer type",
+                            "Required": false,
+                            "@openapi.type": "integer"
                         }
                     ],
                     "CustomQueryOptions": [
diff --git a/test/lib/compile/data/custom-parameters.openapi3.json b/test/lib/compile/data/custom-parameters.openapi3.json
index a194804..42ad6db 100644
--- a/test/lib/compile/data/custom-parameters.openapi3.json
+++ b/test/lib/compile/data/custom-parameters.openapi3.json
@@ -283,6 +283,25 @@
               }
             }
           },
+          {
+            "name": "custom-insert-typed",
+            "in": "header",
+            "required": false,
+            "description": "Custom Header with explicit boolean type and default",
+            "schema": {
+              "type": "boolean",
+              "default": true
+            }
+          },
+          {
+            "name": "custom-insert-integer",
+            "in": "header",
+            "required": false,
+            "description": "Custom Header with explicit integer type",
+            "schema": {
+              "type": "integer"
+            }
+          },
           {
             "name": "customInsert",
             "in": "query",