fix(flatpak): invalid fontconfig cache breaks emoji rendering

src/app/AppConfig.ts

@@ -31,6 +31,15 @@ function getAppConfigFilePath() {
  * Stored in the application data directory.
  */
 export type AppConfig = {
+	// ----------------
+	// Internal
+	// ----------------
+
+	/**
+	 * Last application version when the app was running
+	 */
+	lastAppVersion?: string
+
 	// ----------------
 	// General settings
 	// ----------------

src/app/migration.service.ts

@@ -0,0 +1,67 @@
+/*!
+ * SPDX-FileCopyrightText: 2026 Nextcloud GmbH and Nextcloud contributors
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ */
+
+import type { Awaitable } from '../shared/utils.types.ts'
+
+import gt from 'semver/functions/gt.js'
+import { version } from '../../package.json' with { type: 'json' }
+import { getAppConfig, setAppConfig } from './AppConfig.ts'
+import { migrations } from './migrations/migrations.ts'
+
+export type Migration = {
+	/** Migration name for logging purposes */
+	name: string
+
+	/** Whether to run this migration on the first start of the application after installation */
+	onFirstStart?: boolean
+
+	/** Whether to run this migration on application upgrade */
+	onUpgrade?: boolean
+
+	/** Determine whether the migration should run if it is only needed in certain conditions */
+	validator?: () => Awaitable<boolean>
+
+	/** Migration execution */
+	up(): Awaitable<void>
+}
+
+/**
+ * Run migration
+ *
+ * @param migration - Migration
+ */
+async function runMigration(migration: Migration): Promise<void> {
+	const lastAppVersion = getAppConfig('lastAppVersion')
+
+	const matchesFirstStart = migration.onFirstStart && !lastAppVersion
+	const matchesUpgrade = migration.onUpgrade && lastAppVersion && gt(version, lastAppVersion)
+	if (!matchesFirstStart && !matchesUpgrade) {
+		return
+	}
+
+	const matchesValidator = await migration.validator?.() ?? true
+	if (!matchesValidator) {
+		return
+	}
+
+	try {
+		console.log(`Running migration "${migration.name}"`)
+		await migration.up()
+	} catch (error) {
+		console.error(`Unexpected exception during migration "${migration.name}":`, (error as Error).message)
+	}
+}
+
+/**
+ * Run all migrations and update last version
+ */
+export async function runMigrations() {
+	for (const migration of migrations) {
+		await runMigration(migration)
+	}
+
+	// Migrations are complete - now the app is on the new version
+	setAppConfig('lastAppVersion', version)
+}

src/app/migrations/01-clearFlatpakFontConfigCache.migration.ts

@@ -0,0 +1,27 @@
+/*!
+ * SPDX-FileCopyrightText: 2026 Nextcloud GmbH and Nextcloud contributors
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ */
+
+import type { Migration } from '../migration.service.ts'
+
+import { clearFlatpakFontConfigCache, isFlatpak } from '../system.utils.ts'
+
+/**
+ * Manually clear font config cache for Flatpak installations.
+ * Fixes issues with font rendering like incorrect Emoji font.
+ */
+export const clearFlatpakFontConfigCacheMigration: Migration = {
+	name: 'Clear flatpak font config cache',
+
+	onFirstStart: true,
+
+	validator(): boolean {
+		// Flatpak specific problem
+		return isFlatpak
+	},
+
+	async up() {
+		await clearFlatpakFontConfigCache()
+	},
+}

src/app/migrations/migrations.ts

@@ -0,0 +1,12 @@
+/*!
+ * SPDX-FileCopyrightText: 2026 Nextcloud GmbH and Nextcloud contributors
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ */
+
+import type { Migration } from '../migration.service.ts'
+
+import { clearFlatpakFontConfigCacheMigration } from './01-clearFlatpakFontConfigCache.migration.ts'
+
+export const migrations: Migration[] = [
+	clearFlatpakFontConfigCacheMigration,
+]

src/app/system.utils.ts

@@ -3,6 +3,7 @@
  * SPDX-License-Identifier: AGPL-3.0-or-later
  */
 
+import { rm } from 'node:fs/promises'
 import os from 'node:os'
 import path from 'node:path'
 import { BUILD_CONFIG } from '../shared/build.config.ts'
@@ -100,3 +101,23 @@ export function isSameExecution(argv0: string, cwd: string) {
 
 	return execPath === process.execPath
 }
+
+/**
+ * Manually clear font config cache for Flatpak installations.
+ * Fixes issues with font rendering like incorrect Emoji font.
+ *
+ * @see https://github.com/nextcloud/talk-desktop/issues/1514
+ */
+export async function clearFlatpakFontConfigCache() {
+	if (!process.env.XDG_CACHE_HOME) {
+		console.error('Failed to clear font config cache: $XDG_CACHE_HOME is not defined')
+		return
+	}
+
+	try {
+		// Note: clearing with "fc-cache" command did not help with the issue (was tested with many users and colleagues)
+		await rm(path.join(process.env.XDG_CACHE_HOME, 'fontconfig'), { recursive: true, force: true })
+	} catch (error) {
+		console.error(`Failed to remove font config cache: ${(error as Error).message}`)
+	}
+}

src/main.js

@@ -16,6 +16,7 @@ const { openChromeWebRtcInternals } = require('./app/dev.utils.ts')
 const { triggerDownloadUrl } = require('./app/downloads.ts')
 const { setupReleaseNotificationScheduler } = require('./app/githubReleaseNotification.service.js')
 const { initLaunchAtStartupListener } = require('./app/launchAtStartup.config.ts')
+const { runMigrations } = require('./app/migration.service.ts')
 const { systemInfo, isLinux, isMac, isWindows, isSameExecution } = require('./app/system.utils.ts')
 const { applyTheme } = require('./app/theme.config.ts')
 const { buildTitle } = require('./app/utils.ts')
@@ -80,7 +81,6 @@ if (!app.requestSingleInstanceLock()) {
 	app.quit()
 }
 
-
 ipcMain.on('app:quit', () => app.quit())
 ipcMain.handle('app:getSystemInfo', () => systemInfo)
 ipcMain.handle('app:buildTitle', (event, title) => buildTitle(title))
@@ -141,6 +141,8 @@ let isInWindowRelaunch = false
 
 app.whenReady().then(async () => {
 	await loadAppConfig()
+	await runMigrations()
+
 	applyTheme()
 	initLaunchAtStartupListener()
 	registerAppProtocolHandler()

src/shared/utils.types.ts

@@ -0,0 +1,6 @@
+/*!
+ * SPDX-FileCopyrightText: 2026 Nextcloud GmbH and Nextcloud contributors
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ */
+
+export type Awaitable<T> = T | PromiseLike<T>