From 45eda4401029ee015bd5f80d063a943e72f8ee24 Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Fri, 20 Feb 2026 11:14:08 +0000
Subject: [PATCH 1/3] Initial plan


From f48a1ae6964f82586c20b763960e3cdad2d0d70f Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Fri, 20 Feb 2026 11:21:40 +0000
Subject: [PATCH 2/3] Fix ConfigFile parser warning on
 definePreview({...}).type<T>() chaining

Co-authored-by: valentinpalkovic <5889929+valentinpalkovic@users.noreply.github.com>
---
 code/core/src/csf-tools/ConfigFile.test.ts | 17 +++++++++++++++++
 code/core/src/csf-tools/ConfigFile.ts      | 13 ++++++++++---
 2 files changed, 27 insertions(+), 3 deletions(-)

diff --git a/code/core/src/csf-tools/ConfigFile.test.ts b/code/core/src/csf-tools/ConfigFile.test.ts
index f702579aeecd..191989b1751b 100644
--- a/code/core/src/csf-tools/ConfigFile.test.ts
+++ b/code/core/src/csf-tools/ConfigFile.test.ts
@@ -293,6 +293,23 @@ describe('ConfigFile', () => {
           )
         ).toEqual(['test', 'vitest', '!a11ytest']);
       });
+      it('parses correctly with .type<T>() chaining on export default', () => {
+        const source = dedent`
+          import { definePreview } from '@storybook/react-vite';
+
+          export default definePreview({
+            parameters: {
+              foo: 'bar',
+            },
+          }).type<{
+            parameters: {
+              customParam?: string;
+            };
+          }>();
+        `;
+        const config = loadConfig(source).parse();
+        expect(config.getFieldValue(['parameters', 'foo'])).toEqual('bar');
+      });
     });
   });
 
diff --git a/code/core/src/csf-tools/ConfigFile.ts b/code/core/src/csf-tools/ConfigFile.ts
index c5f376f5096f..79aa5a9d886f 100644
--- a/code/core/src/csf-tools/ConfigFile.ts
+++ b/code/core/src/csf-tools/ConfigFile.ts
@@ -204,9 +204,16 @@ export class ConfigFile {
           self.hasDefaultExport = true;
           let decl = self._resolveDeclaration(node.declaration as t.Node, parent);
 
-          // csf factory
-          if (t.isCallExpression(decl) && t.isObjectExpression(decl.arguments[0])) {
-            decl = decl.arguments[0];
+          // csf factory - unwrap call expressions like definePreview({...}) or definePreview({...}).type<T>()
+          while (t.isCallExpression(decl)) {
+            if (t.isObjectExpression(decl.arguments[0])) {
+              decl = decl.arguments[0];
+              break;
+            } else if (t.isMemberExpression(decl.callee) && t.isCallExpression(decl.callee.object)) {
+              decl = decl.callee.object;
+            } else {
+              break;
+            }
           }
 
           if (t.isObjectExpression(decl)) {

From 2bdb54a73586347cdc6303ff119bb0cb778073be Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Tue, 3 Mar 2026 09:46:37 +0000
Subject: [PATCH 3/3] Fix prettier formatting in ConfigFile.ts

Co-authored-by: valentinpalkovic <5889929+valentinpalkovic@users.noreply.github.com>
---
 code/core/src/csf-tools/ConfigFile.ts | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/code/core/src/csf-tools/ConfigFile.ts b/code/core/src/csf-tools/ConfigFile.ts
index 79aa5a9d886f..6e326004c82d 100644
--- a/code/core/src/csf-tools/ConfigFile.ts
+++ b/code/core/src/csf-tools/ConfigFile.ts
@@ -209,7 +209,10 @@ export class ConfigFile {
             if (t.isObjectExpression(decl.arguments[0])) {
               decl = decl.arguments[0];
               break;
-            } else if (t.isMemberExpression(decl.callee) && t.isCallExpression(decl.callee.object)) {
+            } else if (
+              t.isMemberExpression(decl.callee) &&
+              t.isCallExpression(decl.callee.object)
+            ) {
               decl = decl.callee.object;
             } else {
               break;