fix: Close viewer if we navigate back in browser history

cypress/e2e/navigation.cy.ts

@@ -0,0 +1,29 @@
+/**
+ * SPDX-FileCopyrightText: 2025 Nextcloud GmbH and Nextcloud contributors
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ */
+
+describe('Browser navigation', function() {
+	before(function() {
+		// Init user
+		cy.createRandomUser().then(user => {
+			// Upload test files
+			cy.uploadFile(user, 'image.png', 'image/png', '/image1.png')
+
+			// Visit nextcloud
+			cy.login(user)
+			cy.visit('/apps/files')
+		})
+	})
+	after(function() {
+		cy.logout()
+	})
+
+	it('Navigating back to the files overview', function() {
+		cy.getFile('image1.png', { timeout: 10000 })
+		cy.openFile('image1.png')
+		cy.get('body > .viewer').should('be.visible')
+		cy.go('back')
+		cy.get('body > .viewer').should('not.exist')
+	})
+})

src/files_actions/viewerAction.ts

@@ -22,6 +22,13 @@
 	)
 }
 
+const onPopState = () => {
+	if (window.OCP.Files.Router.query.openfile !== 'true') {
+		window.OCA.Viewer.close()
+		window.removeEventListener('popstate', onPopState)
+	}
+}
+
 /**
  * Execute the viewer files action
  * @param node The active node
@@ -36,6 +43,8 @@
 		window.OCP.Files.Router.goToRoute(null, window.OCP.Files.Router.params, newQuery)
 	}
 
+	window.addEventListener('popstate', onPopState)
+
 	pushToHistory(node, view, dir)
 	window.OCA.Viewer.open({
 		path: node.path,
@@ -45,7 +54,7 @@
 		onNext(fileInfo) {
 			pushToHistory(fileInfo, view, dir)
 		},
 		onClose
 	})
 
 	return null