docs: document batch API endpoint

TODO.md

@@ -144,48 +144,20 @@ and report() methods. Integrated into main loop with configurable stats_interval
 
 ---
 
-### [ ] 15. Unit Test Infrastructure
+### [x] 15. Unit Test Infrastructure
 
-**Problem:** No automated tests. Changes can break existing functionality silently.
+**Completed.** Added pytest-based test suite with comprehensive coverage.
+- tests/conftest.py: Shared fixtures (temp_db, proxy_db, sample_proxies, etc.)
+- tests/test_dbs.py: 40 tests for database operations (CDN filtering, latency, stats)
+- tests/test_fetch.py: 60 tests for proxy validation (skipped in Python 3)
+- tests/test_misc.py: 39 tests for utilities (timestamp, log levels, SSL errors)
+- tests/mock_network.py: Network mocking infrastructure
 
-**Implementation:**
 ```
-tests/
-├── __init__.py
-├── test_proxy_utils.py    # Test IP validation, cleansing
-├── test_extract.py        # Test proxy/URL extraction
-├── test_database.py       # Test DB operations with temp DB
-└── mock_network.py        # Mock rocksock for offline testing
+Test Results: 79 passed, 60 skipped (Python 2 only)
+Run with: python3 -m pytest tests/ -v
 ```
 
-```python
-# tests/test_proxy_utils.py
-import unittest
-import sys
-sys.path.insert(0, '..')
-import fetch
-
-class TestProxyValidation(unittest.TestCase):
-    def test_valid_proxy(self):
-        self.assertTrue(fetch.is_usable_proxy('8.8.8.8:8080'))
-
-    def test_private_ip_rejected(self):
-        self.assertFalse(fetch.is_usable_proxy('192.168.1.1:8080'))
-        self.assertFalse(fetch.is_usable_proxy('10.0.0.1:8080'))
-        self.assertFalse(fetch.is_usable_proxy('172.16.0.1:8080'))
-
-    def test_invalid_port_rejected(self):
-        self.assertFalse(fetch.is_usable_proxy('8.8.8.8:0'))
-        self.assertFalse(fetch.is_usable_proxy('8.8.8.8:99999'))
-
-if __name__ == '__main__':
-    unittest.main()
-```
-
-**Files:** tests/ directory
-**Effort:** High (initial), Low (ongoing)
-**Risk:** Low
-
 ---
 
 ## Long Term (Future)
@@ -261,6 +233,31 @@ if __name__ == '__main__':
 
 ---
 
+### [x] 23. Batch API Endpoint
+
+**Completed.** Added `/api/dashboard` batch endpoint combining stats, workers, and countries.
+
+**Implementation:**
+- `httpd.py`: New `/api/dashboard` endpoint returns combined data in single response
+- `httpd.py`: Refactored `/api/workers` to use `_get_workers_data()` helper method
+- `dashboard.js`: Updated `fetchStats()` to use batch endpoint instead of multiple calls
+
+**Response Structure:**
+```json
+{
+  "stats": { /* same as /api/stats */ },
+  "workers": { /* same as /api/workers */ },
+  "countries": { /* same as /api/countries */ }
+}
+```
+
+**Benefit:**
+- Reduces dashboard polling from 2 HTTP requests to 1 per poll cycle
+- Lower RTT impact over SSH tunnels and high-latency connections
+- Single database connection serves all data
+
+---
+
 ## Profiling-Based Performance Optimizations
 
 **Baseline:** 30-minute profiling session, 25.6M function calls, 1842s runtime
@@ -446,6 +443,8 @@ above target the remaining 31.3% of CPU-bound operations.
 - [ ] Configurable refresh interval via URL param or localStorage
 - [x] Pause polling when browser tab not visible (Page Visibility API)
 - [x] Skip chart rendering for inactive dashboard tabs (reduces CPU)
+- [ ] Batch API endpoints - combine /api/stats, /api/workers, /api/countries into
+      single /api/dashboard call to reduce round-trips (helps SSH tunnel latency)
 
 ### [ ] Dashboard Feature Ideas