diff --git a/tests/test_token_tracker.py b/tests/test_token_tracker.py
new file mode 100644
index 00000000..dd58340f
--- /dev/null
+++ b/tests/test_token_tracker.py
@@ -0,0 +1,159 @@
+"""
+Tests for scripts/token_tracker.py — Token Budget Tracker.
+"""
+
+import json
+import os
+import sqlite3
+import tempfile
+import unittest
+from pathlib import Path
+
+import sys
+sys.path.insert(0, str(Path(__file__).parent.parent / "scripts"))
+from token_tracker import (
+    get_db,
+    record_usage,
+    get_usage_since,
+    get_hourly_usage,
+    get_worker_usage,
+    format_tokens,
+    progress_bar,
+    estimate_eta,
+    check_alerts,
+    load_budgets,
+    save_budgets,
+)
+
+
+class TestTokenTracker(unittest.TestCase):
+    def setUp(self):
+        self.tmpdir = tempfile.mkdtemp()
+        self.db_path = Path(self.tmpdir) / "test.db"
+        self.conn = get_db(self.db_path)
+
+    def tearDown(self):
+        self.conn.close()
+
+    def test_record_usage(self):
+        record_usage(self.conn, "pipeline1", "worker1", 1000)
+        cursor = self.conn.execute("SELECT pipeline, worker, tokens FROM token_usage")
+        row = cursor.fetchone()
+        self.assertEqual(row, ("pipeline1", "worker1", 1000))
+
+    def test_get_usage_since(self):
+        record_usage(self.conn, "p1", "w1", 500)
+        record_usage(self.conn, "p1", "w2", 300)
+        record_usage(self.conn, "p2", "w1", 200)
+
+        usage = get_usage_since(self.conn, "2020-01-01T00:00:00")
+        self.assertEqual(usage["p1"], 800)
+        self.assertEqual(usage["p2"], 200)
+
+    def test_get_worker_usage(self):
+        record_usage(self.conn, "p1", "w1", 500)
+        record_usage(self.conn, "p1", "w2", 300)
+        record_usage(self.conn, "p1", "w1", 100)
+
+        workers = get_worker_usage(self.conn, "p1", "2020-01-01T00:00:00")
+        self.assertEqual(workers["w1"], 600)
+        self.assertEqual(workers["w2"], 300)
+
+
+class TestFormatTokens(unittest.TestCase):
+    def test_billions(self):
+        self.assertEqual(format_tokens(1_500_000_000), "1.5B")
+
+    def test_millions(self):
+        self.assertEqual(format_tokens(45_200_000), "45.2M")
+
+    def test_thousands(self):
+        self.assertEqual(format_tokens(1_500), "1.5K")
+
+    def test_small(self):
+        self.assertEqual(format_tokens(42), "42")
+
+    def test_zero(self):
+        self.assertEqual(format_tokens(0), "0")
+
+
+class TestProgressBar(unittest.TestCase):
+    def test_empty(self):
+        self.assertEqual(progress_bar(0, 100), "░" * 10)
+
+    def test_half(self):
+        bar = progress_bar(50, 100)
+        self.assertEqual(bar, "█████░░░░░")
+
+    def test_full(self):
+        self.assertEqual(progress_bar(100, 100), "█" * 10)
+
+    def test_overfull(self):
+        self.assertEqual(progress_bar(150, 100), "█" * 10)
+
+    def test_zero_target(self):
+        self.assertEqual(progress_bar(0, 0), "░" * 10)
+
+
+class TestEstimateEta(unittest.TestCase):
+    def test_done(self):
+        self.assertEqual(estimate_eta(100, 100, 1), "DONE")
+
+    def test_hours(self):
+        eta = estimate_eta(50, 100, 1)
+        self.assertEqual(eta, "1.0h")
+
+    def test_minutes(self):
+        eta = estimate_eta(90, 100, 1)
+        self.assertIn("m", eta)  # Should be in minutes format
+
+    def test_no_data(self):
+        self.assertEqual(estimate_eta(0, 100, 1), "N/A")
+
+
+class TestCheckAlerts(unittest.TestCase):
+    def test_no_alerts(self):
+        usage = {"p1": 100}
+        budgets = {"p1": 1000}
+        alerts = check_alerts(usage, budgets)
+        self.assertEqual(alerts, [])
+
+    def test_50_percent(self):
+        usage = {"p1": 500}
+        budgets = {"p1": 1000}
+        alerts = check_alerts(usage, budgets)
+        self.assertTrue(any("50" in a for a in alerts))
+
+    def test_80_percent(self):
+        usage = {"p1": 800}
+        budgets = {"p1": 1000}
+        alerts = check_alerts(usage, budgets)
+        self.assertTrue(any("80" in a for a in alerts))
+
+    def test_100_percent(self):
+        usage = {"p1": 1000}
+        budgets = {"p1": 1000}
+        alerts = check_alerts(usage, budgets)
+        self.assertTrue(any("100" in a for a in alerts))
+
+    def test_over_budget(self):
+        usage = {"p1": 1500}
+        budgets = {"p1": 1000}
+        alerts = check_alerts(usage, budgets)
+        self.assertTrue(len(alerts) >= 3)  # 50%, 80%, 100% all triggered
+        self.assertTrue(any("🔴" in a for a in alerts))
+
+
+class TestBudgets(unittest.TestCase):
+    def test_save_load(self):
+        tmpfile = tempfile.mktemp(suffix=".json")
+        budgets = {"p1": 100, "p2": 200}
+        save_budgets(budgets)
+        # Reset and reload
+        from token_tracker import BUDGETS_FILE
+        loaded = load_budgets()
+        self.assertIn("p1", loaded)
+
+
+if __name__ == "__main__":
+    unittest.main()