From 04e877379149431d30d070b0edc86cd614c43f12 Mon Sep 17 00:00:00 2001
From: David Velasquez <david.velasquez@marvik.ai>
Date: Mon, 8 Jun 2026 16:40:01 -0500
Subject: [PATCH 1/2] Fix: honor `nullable: true` on object types with
 additionalProperties

`nonArraySchemaObjectTypeToTs` wraps the non-dictionary return in its
`case "object"` branch via `appendNullToUnion(..., item.nullable)`, but
the dictionary return (`additionalProperties` is truthy) did not. The
same pattern exists in `schemaObjectTypeNode`, which short-circuits to
`createDictionaryType` before reaching the switch and also dropped
`item.nullable`. Every other type branch handles `item.nullable`;
these two dictionary paths were the only exceptions.

Result: schemas like

    type: object
    additionalProperties: true
    nullable: true

generated `{ [key: string]: any }` instead of
`{ [key: string]: any } | null`, silently dropping the null case.

Added regression coverage for both shapes:
- `additionalProperties: true` + `nullable: true`
- `additionalProperties: { type: "string" }` + `nullable: true`
---
 spec/common/types.spec.ts | 18 ++++++++++++++++++
 src/common/util.ts        |  7 +++++--
 2 files changed, 23 insertions(+), 2 deletions(-)

diff --git a/spec/common/types.spec.ts b/spec/common/types.spec.ts
index 8e2d7e5..e4a2789 100644
--- a/spec/common/types.spec.ts
+++ b/spec/common/types.spec.ts
@@ -70,6 +70,12 @@ export type MyDictionaryValueNested = {
         };
     };
 };
+export type MyNullableDictionary = {
+    [key: string]: any;
+} | null;
+export type MyNullableDictionaryString = {
+    [key: string]: string;
+} | null;
 `;
 
 describe("makeTypes", () => {
@@ -293,6 +299,18 @@ describe("makeTypes", () => {
               },
             },
           },
+          MyNullableDictionary: {
+            type: "object",
+            additionalProperties: true,
+            nullable: true,
+          },
+          MyNullableDictionaryString: {
+            type: "object",
+            additionalProperties: {
+              type: "string",
+            },
+            nullable: true,
+          },
         },
       },
     };
diff --git a/src/common/util.ts b/src/common/util.ts
index e5387f1..89ec5e6 100644
--- a/src/common/util.ts
+++ b/src/common/util.ts
@@ -137,7 +137,7 @@ export function schemaObjectTypeNode(
   }
 
   if (item.additionalProperties) {
-    return createDictionaryType($refs, item);
+    return appendNullToUnion(createDictionaryType($refs, item), item.nullable);
   }
 
   if (item.properties) {
@@ -253,7 +253,10 @@ export function nonArraySchemaObjectTypeToTs(
       );
     case "object": {
       if (item.additionalProperties) {
-        return createDictionaryType($refs, item);
+        return appendNullToUnion(
+          createDictionaryType($refs, item),
+          item.nullable
+        );
       }
 
       return appendNullToUnion(

From 8d393b25acd603e5bdc948c4f11ba2654aa525ae Mon Sep 17 00:00:00 2001
From: David Velasquez <david.velasquez@marvik.ai>
Date: Mon, 8 Jun 2026 16:46:34 -0500
Subject: [PATCH 2/2] Update changelog for nullable dictionary types fix

---
 changelog.md | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/changelog.md b/changelog.md
index 77c4805..25e0710 100644
--- a/changelog.md
+++ b/changelog.md
@@ -59,3 +59,7 @@ A major release with breaking changes. Involves updating type signatures to matc
 ### 3.5.4
 
 - Fix for @tanstack/query v5.89.0 onError, onSuccess and onSettled signature change referenced in issue 9660
+
+### 3.5.5
+
+- Fix `nullable: true` not being honored for `object` types with `additionalProperties` (dictionary types). Both code paths in `src/common/util.ts` now wrap the dictionary type with `appendNullToUnion` so `| null` is appended when `nullable: true` is set.