From e220589506824d48b82103ccd3856dfb895880fd Mon Sep 17 00:00:00 2001
From: Patrik Oldsberg <poldsberg@gmail.com>
Date: Thu, 19 Mar 2026 13:43:08 +0100
Subject: [PATCH] frontend-plugin-api: remove defineParams from
 PluginHeaderActionBlueprint

Replace the defineParams + createExtensionBlueprintParams pattern with
inline param types on the factory, matching PageBlueprint, SubPageBlueprint,
and other blueprints. Update the app-visualizer usage accordingly.

Signed-off-by: Patrik Oldsberg <poldsberg@gmail.com>
Made-with: Cursor
---
 .../remove-plugin-header-action-define-params.md      |  5 +++++
 .changeset/update-app-visualizer-header-action.md     |  5 +++++
 packages/frontend-plugin-api/report.api.md            |  6 ++----
 .../src/blueprints/PluginHeaderActionBlueprint.tsx    | 11 ++---------
 plugins/app-visualizer/report.api.md                  |  7 ++-----
 plugins/app-visualizer/src/plugin.tsx                 |  9 ++++-----
 6 files changed, 20 insertions(+), 23 deletions(-)
 create mode 100644 .changeset/remove-plugin-header-action-define-params.md
 create mode 100644 .changeset/update-app-visualizer-header-action.md

diff --git a/.changeset/remove-plugin-header-action-define-params.md b/.changeset/remove-plugin-header-action-define-params.md
new file mode 100644
index 0000000000..8bbdf99466
--- /dev/null
+++ b/.changeset/remove-plugin-header-action-define-params.md
@@ -0,0 +1,5 @@
+---
+'@backstage/frontend-plugin-api': minor
+---
+
+**BREAKING**: Removed the `defineParams` callback from `PluginHeaderActionBlueprint`. Params are now typed inline on the factory, matching the pattern used by `PageBlueprint`, `SubPageBlueprint`, and others. To migrate, change `params: defineParams => defineParams({ ... })` to `params: { ... }` when calling `PluginHeaderActionBlueprint.make(...)`.
diff --git a/.changeset/update-app-visualizer-header-action.md b/.changeset/update-app-visualizer-header-action.md
new file mode 100644
index 0000000000..e95e84eb43
--- /dev/null
+++ b/.changeset/update-app-visualizer-header-action.md
@@ -0,0 +1,5 @@
+---
+'@backstage/plugin-app-visualizer': patch
+---
+
+Updated `PluginHeaderActionBlueprint` usage to pass params as a plain object.
diff --git a/packages/frontend-plugin-api/report.api.md b/packages/frontend-plugin-api/report.api.md
index c3936ba0da..7008aae801 100644
--- a/packages/frontend-plugin-api/report.api.md
+++ b/packages/frontend-plugin-api/report.api.md
@@ -1951,11 +1951,9 @@ export type PendingOAuthRequest = {
 // @public
 export const PluginHeaderActionBlueprint: ExtensionBlueprint_2<{
   kind: 'plugin-header-action';
-  params: (params: {
+  params: {
     loader: () => Promise<JSX.Element>;
-  }) => ExtensionBlueprintParams_2<{
-    loader: () => Promise<JSX.Element>;
-  }>;
+  };
   output: ExtensionDataRef_2<JSX_2, 'core.reactElement', {}>;
   inputs: {};
   config: {};
diff --git a/packages/frontend-plugin-api/src/blueprints/PluginHeaderActionBlueprint.tsx b/packages/frontend-plugin-api/src/blueprints/PluginHeaderActionBlueprint.tsx
index 84ed9da7ff..eb0c24420d 100644
--- a/packages/frontend-plugin-api/src/blueprints/PluginHeaderActionBlueprint.tsx
+++ b/packages/frontend-plugin-api/src/blueprints/PluginHeaderActionBlueprint.tsx
@@ -16,11 +16,7 @@
 
 import { lazy as reactLazy } from 'react';
 import { ExtensionBoundary } from '../components';
-import {
-  coreExtensionData,
-  createExtensionBlueprint,
-  createExtensionBlueprintParams,
-} from '../wiring';
+import { coreExtensionData, createExtensionBlueprint } from '../wiring';
 
 /**
  * Creates extensions that provide plugin-scoped header actions.
@@ -36,10 +32,7 @@ export const PluginHeaderActionBlueprint = createExtensionBlueprint({
   kind: 'plugin-header-action',
   attachTo: { id: 'api:app/plugin-header-actions', input: 'actions' },
   output: [coreExtensionData.reactElement],
-  defineParams(params: { loader: () => Promise<JSX.Element> }) {
-    return createExtensionBlueprintParams(params);
-  },
-  *factory(params, { node }) {
+  *factory(params: { loader: () => Promise<JSX.Element> }, { node }) {
     const LazyAction = reactLazy(() =>
       params.loader().then(element => ({ default: () => element })),
     );
diff --git a/plugins/app-visualizer/report.api.md b/plugins/app-visualizer/report.api.md
index 9ee06eccb0..ba29cb92dc 100644
--- a/plugins/app-visualizer/report.api.md
+++ b/plugins/app-visualizer/report.api.md
@@ -5,7 +5,6 @@
 ```ts
 import { AnyRouteRefParams } from '@backstage/frontend-plugin-api';
 import { ConfigurableExtensionDataRef } from '@backstage/frontend-plugin-api';
-import { ExtensionBlueprintParams } from '@backstage/frontend-plugin-api';
 import { ExtensionDataRef } from '@backstage/frontend-plugin-api';
 import { ExtensionInput } from '@backstage/frontend-plugin-api';
 import { IconComponent } from '@backstage/frontend-plugin-api';
@@ -124,11 +123,9 @@ const visualizerPlugin: OverridableFrontendPlugin<
       configInput: {};
       output: ExtensionDataRef<JSX_2.Element, 'core.reactElement', {}>;
       inputs: {};
-      params: (params: {
+      params: {
         loader: () => Promise<JSX.Element>;
-      }) => ExtensionBlueprintParams<{
-        loader: () => Promise<JSX.Element>;
-      }>;
+      };
     }>;
     'sub-page:app-visualizer/details': OverridableExtensionDefinition<{
       kind: 'sub-page';
diff --git a/plugins/app-visualizer/src/plugin.tsx b/plugins/app-visualizer/src/plugin.tsx
index 9fa7b2cd72..fab8479c54 100644
--- a/plugins/app-visualizer/src/plugin.tsx
+++ b/plugins/app-visualizer/src/plugin.tsx
@@ -76,11 +76,10 @@ const appVisualizerTextPage = SubPageBlueprint.make({
 });
 
 const copyTreeAsJson = PluginHeaderActionBlueprint.make({
-  params: defineParams =>
-    defineParams({
-      loader: () =>
-        import('./components/CopyTreeButton').then(m => <m.CopyTreeButton />),
-    }),
+  params: {
+    loader: () =>
+      import('./components/CopyTreeButton').then(m => <m.CopyTreeButton />),
+  },
 });
 
 export const appVisualizerNavItem = NavItemBlueprint.make({