diff --git a/.gitignore b/.gitignore
index 47078f4c8..bf179d8cd 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,2 +1,3 @@
 /node_modules/
 yarn-error.log*
+coverage/
\ No newline at end of file
diff --git a/packages/nicolium/tsconfig.json b/packages/nicolium/tsconfig.json
index 06614820d..8d8c5205b 100644
--- a/packages/nicolium/tsconfig.json
+++ b/packages/nicolium/tsconfig.json
@@ -18,5 +18,5 @@
     "typeRoots": ["./src/types", "./node_modules/@types", "./node_modules"],
     "types": ["vite/client", "vite-plugin-compile-time/client", "dom-chromium-ai"]
   },
-  "exclude": ["src/**/*.test.ts", "src/**/*.test.tsx"]
+  "exclude": ["tests/**/*.test.ts", "tests/**/*.test.tsx"]
 }
diff --git a/packages/pl-api/package.json b/packages/pl-api/package.json
index 2713706f0..596aff2ef 100644
--- a/packages/pl-api/package.json
+++ b/packages/pl-api/package.json
@@ -24,7 +24,10 @@
     "lint": "oxlint",
     "fmt": "oxfmt",
     "fmt:check": "oxfmt --check",
-    "precommit": "lint-staged"
+    "precommit": "lint-staged",
+    "test": "vitest run",
+    "test:watch": "vitest",
+    "test:coverage": "vitest run --coverage"
   },
   "dependencies": {
     "blurhash": "^2.0.5",
@@ -39,6 +42,7 @@
     "@types/http-link-header": "^1.0.7",
     "@types/node": "^25.3.0",
     "@types/semver": "^7.7.1",
+    "@vitest/coverage-v8": "4.0.18",
     "oxfmt": "^0.35.0",
     "oxlint": "^1.50.0",
     "typedoc": "^0.28.17",
@@ -47,6 +51,7 @@
     "typescript": "^5.9.3",
     "vite": "^7.3.1",
     "vite-plugin-dts": "^4.5.4",
+    "vitest": "^4.0.18",
     "ws": "^8.19.0"
   },
   "lint-staged": {
diff --git a/packages/pl-api/tests/utils/accounts.test.ts b/packages/pl-api/tests/utils/accounts.test.ts
new file mode 100644
index 000000000..2199ca942
--- /dev/null
+++ b/packages/pl-api/tests/utils/accounts.test.ts
@@ -0,0 +1,29 @@
+import { describe, expect, it } from 'vitest';
+
+import { isDefaultAvatar, isDefaultHeader } from '@/utils/accounts';
+
+describe('isDefaultHeader', () => {
+  it('detects GoToSocial default header', () => {
+    expect(isDefaultHeader('https://gts.mkljczk.pl/assets/default_header.webp')).toBe(true);
+  });
+
+  it('detects NeoDB default headers', () => {
+    expect(isDefaultHeader('https://neodb.social/static/img/missing.5fa23ea9f65e.png')).toBe(true);
+  });
+});
+
+describe('isDefaultAvatar', () => {
+  it('detects GoToSocial default avatar', () => {
+    expect(
+      isDefaultAvatar('https://gts.mkljczk.pl/assets/default_avatars/GoToSocial_icon4.webp'),
+    ).toBe(true);
+  });
+
+  it('returns false for non-default avatar', () => {
+    expect(
+      isDefaultAvatar(
+        'https://example.com/fileserver/01Z0G3Q7MWJ7DKMFYA2DDZ9T32/attachment/original/01KGZ1PKJF1JJ4GVKRBB2F2QME.jpegavatar.jpg',
+      ),
+    ).toBe(false);
+  });
+});
diff --git a/packages/pl-api/tsconfig.json b/packages/pl-api/tsconfig.json
index 46095c7f4..534dfa6ca 100644
--- a/packages/pl-api/tsconfig.json
+++ b/packages/pl-api/tsconfig.json
@@ -5,6 +5,9 @@
     "module": "ESNext",
     "lib": ["ES2020", "DOM", "DOM.Iterable"],
     "skipLibCheck": true,
+    "paths": {
+      "@/*": ["./src/*"]
+    },
 
     /* Bundler mode */
     "moduleResolution": "bundler",
diff --git a/packages/pl-api/vite.config.ts b/packages/pl-api/vite.config.ts
index d14779539..e91dcda96 100644
--- a/packages/pl-api/vite.config.ts
+++ b/packages/pl-api/vite.config.ts
@@ -1,3 +1,4 @@
+import { fileURLToPath, URL } from 'node:url';
 import { resolve } from 'path';
 
 import { defineConfig } from 'vite';
@@ -5,7 +6,7 @@ import dts from 'vite-plugin-dts';
 
 import pkg from './package.json';
 
-export default defineConfig({
+export default defineConfig(() => ({
   plugins: [dts({ include: ['lib'], insertTypesEntry: true })],
   build: {
     copyPublicDir: false,
@@ -21,7 +22,21 @@ export default defineConfig({
       external: Object.keys(pkg.dependencies),
     },
   },
+  resolve: {
+    alias: [
+      {
+        find: '@/',
+        replacement: fileURLToPath(new URL('./lib/', import.meta.url)),
+      },
+    ],
+  },
   server: {
     port: Number(process.env.PORT ?? 7313),
   },
-});
+  test: {
+    globals: true,
+    environment: 'jsdom',
+    include: ['tests/**/*.test.{ts,tsx}'],
+    css: false,
+  },
+}));
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index 59bfd9d64..5a8592b18 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -468,6 +468,9 @@ importers:
       '@types/semver':
         specifier: ^7.7.1
         version: 7.7.1
+      '@vitest/coverage-v8':
+        specifier: 4.0.18
+        version: 4.0.18(vitest@4.0.18(@types/node@25.3.0)(jiti@1.21.7)(jsdom@28.1.0)(lightningcss@1.31.1)(sass-embedded@1.97.3)(sass@1.97.3)(terser@5.46.0)(yaml@2.8.2))
       oxfmt:
         specifier: ^0.35.0
         version: 0.35.0
@@ -492,6 +495,9 @@ importers:
       vite-plugin-dts:
         specifier: ^4.5.4
         version: 4.5.4(@types/node@25.3.0)(rollup@4.57.1)(typescript@5.9.3)(vite@7.3.1(@types/node@25.3.0)(jiti@1.21.7)(lightningcss@1.31.1)(sass-embedded@1.97.3)(sass@1.97.3)(terser@5.46.0)(yaml@2.8.2))
+      vitest:
+        specifier: ^4.0.18
+        version: 4.0.18(@types/node@25.3.0)(jiti@1.21.7)(jsdom@28.1.0)(lightningcss@1.31.1)(sass-embedded@1.97.3)(sass@1.97.3)(terser@5.46.0)(yaml@2.8.2)
       ws:
         specifier: ^8.19.0
         version: 8.19.0