diff --git a/.gitea/workflows/ci.yml b/.gitea/workflows/ci.yml
index b1da228..a75f0c5 100644
--- a/.gitea/workflows/ci.yml
+++ b/.gitea/workflows/ci.yml
@@ -57,9 +57,9 @@ jobs:
         run: |
           if [[ -f pyproject.toml ]]; then
             python3 -m pip install --upgrade pip
-            pip3 install -e ".[dev]" 2>/dev/null || pip3 install -e . 2>/dev/null || true
-            pip3 install pytest
-            pytest tests/ -v --tb=short 2>/dev/null || true
+            pip3 install -r requirements.txt 2>/dev/null || true
+            pip3 install pytest pytest-cov pytest-mock
+            pytest tests/ -v --tb=short --cov=factsdb --cov-report=term-missing --cov-fail-under=90
           else
             echo "No Python project detected, skipping pytest"
           fi
diff --git a/.gitignore b/.gitignore
index cd4115b..419459c 100644
--- a/.gitignore
+++ b/.gitignore
@@ -62,4 +62,10 @@ sample/
 
 # Docker
 .dockerignore
-*.docker
\ No newline at end of file
+*.docker
+
+# Test coverage
+.coverage
+coverage.xml
+htmlcov/
+.pytest_cache/
\ No newline at end of file
diff --git a/pyproject.toml b/pyproject.toml
new file mode 100644
index 0000000..04ea7cf
--- /dev/null
+++ b/pyproject.toml
@@ -0,0 +1,18 @@
+[tool.pytest.ini_options]
+testpaths = ["tests"]
+python_files = ["test_*.py"]
+python_functions = ["test_*"]
+
+[tool.coverage.run]
+source = ["factsdb"]
+omit = ["tests/*", "factsdb/__main__.py", "factsdb/main.py", "factsdb/cli.py", "factsdb/__init__.py"]
+
+[tool.coverage.report]
+show_missing = true
+fail_under = 90
+exclude_lines = [
+    "pragma: no cover",
+    "if __name__ == .__main__.:",
+    "raise NotImplementedError",
+    "pass",
+]
diff --git a/tests/__init__.py b/tests/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/tests/conftest.py b/tests/conftest.py
new file mode 100644
index 0000000..37e8df2
--- /dev/null
+++ b/tests/conftest.py
@@ -0,0 +1,58 @@
+"""Shared fixtures for FactsDB tests."""
+
+import os
+import tempfile
+import pytest
+from unittest.mock import MagicMock, patch
+
+from factsdb.config import Config, DatabaseConfig, AIEndpointConfig, FTPServerConfig, SchedulerConfig
+
+
+@pytest.fixture
+def temp_db_path():
+    """Provide a temporary database path that's cleaned up after the test."""
+    with tempfile.NamedTemporaryFile(suffix=".db", delete=False) as f:
+        path = f.name
+    yield path
+    if os.path.exists(path):
+        os.unlink(path)
+
+
+@pytest.fixture
+def mock_env_vars():
+    """Set required environment variables for Config initialization."""
+    env = {
+        "AI_ENDPOINT_URL": "http://localhost:8000/v1",
+        "AI_ENDPOINT_TOKEN": "test-token-123",
+        "FTP_USERNAME": "testuser",
+        "FTP_PASSWORD": "testpass",
+        "DATABASE_PATH": ":memory:",
+    }
+    old = {}
+    for k, v in env.items():
+        old[k] = os.environ.get(k)
+        os.environ[k] = v
+    yield env
+    for k, v in old.items():
+        if v is None:
+            os.environ.pop(k, None)
+        else:
+            os.environ[k] = v
+
+
+@pytest.fixture
+def config(mock_env_vars):
+    """Provide a fully configured Config instance."""
+    return Config()
+
+
+@pytest.fixture
+def db_config(temp_db_path):
+    """Provide a DatabaseConfig pointing to a temp file."""
+    return DatabaseConfig(path=temp_db_path)
+
+
+@pytest.fixture
+def ai_endpoint_config():
+    """Provide an AIEndpointConfig for testing."""
+    return AIEndpointConfig(url="http://localhost:8000/v1", auth_token="test-token")
diff --git a/tests/test_ai_processor.py b/tests/test_ai_processor.py
new file mode 100644
index 0000000..f001af8
--- /dev/null
+++ b/tests/test_ai_processor.py
@@ -0,0 +1,149 @@
+"""Tests for ai_processor module."""
+
+import pytest
+from unittest.mock import patch, MagicMock
+
+from factsdb.ai_processor import AIEndpointClient, AIProcessor
+from factsdb.config import AIEndpointConfig
+
+
+@pytest.fixture
+def ai_config():
+    return AIEndpointConfig(url="http://localhost:8000/v1", auth_token="tok")
+
+
+@pytest.fixture
+def client(ai_config):
+    return AIEndpointClient(ai_config)
+
+
+class TestAIEndpointClient:
+    def test_headers(self, client):
+        h = client._get_headers()
+        assert h["Authorization"] == "Bearer tok"
+        assert h["Content-Type"] == "application/json"
+
+    def test_base_url_trailing_slash(self):
+        cfg = AIEndpointConfig(url="http://localhost:8000/v1/", auth_token="tok")
+        c = AIEndpointClient(cfg)
+        assert c.base_url == "http://localhost:8000/v1"
+
+
+class TestSendRequest:
+    def test_success(self, client):
+        mock_resp = MagicMock()
+        mock_resp.json.return_value = {"choices": []}
+        mock_resp.raise_for_status.return_value = None
+        with patch("requests.post", return_value=mock_resp) as mp:
+            result = client.send_request({"model": "m"})
+            mp.assert_called_once()
+            assert result == {"choices": []}
+
+    def test_request_failure(self, client):
+        import requests.exceptions
+        with patch("requests.post", side_effect=requests.exceptions.ConnectionError("conn")):
+            with pytest.raises(Exception, match="AI endpoint request failed"):
+                client.send_request({})
+
+
+class TestExtractFacts:
+    def test_single_chunk(self, client):
+        mock_resp = MagicMock()
+        mock_resp.json.return_value = {
+            "choices": [{"message": {"content": '{"fact": "F1", "key_entities": ["E"], "key_dates": ["2024"]}'}}]
+        }
+        mock_resp.raise_for_status.return_value = None
+        with patch("requests.post", return_value=mock_resp):
+            result = client.extract_facts("short text", "")
+        assert result["fact"] == "F1"
+        assert "E" in result["key_entities"]
+        assert "2024" in result["key_dates"]
+
+    def test_chunking(self, client):
+        long_text = "x" * 20000
+        calls = []
+        mock_resp = MagicMock()
+        mock_resp.json.return_value = {
+            "choices": [{"message": {"content": '{"fact": "F1", "key_entities": [], "key_dates": []}'}}]
+        }
+        mock_resp.raise_for_status.return_value = None
+        def side_effect(*a, **kw):
+            calls.append(kw.get("json", {}))
+            return mock_resp
+        with patch("requests.post", side_effect=side_effect):
+            result = client.extract_facts(long_text, "")
+        assert len(calls) >= 2
+        assert result["fact"]
+
+    def test_json_code_block(self, client):
+        mock_resp = MagicMock()
+        mock_resp.json.return_value = {
+            "choices": [{"message": {"content": "```json\n{\"fact\": \"FB\", \"key_entities\": [], \"key_dates\": []}\n```"}}]
+        }
+        mock_resp.raise_for_status.return_value = None
+        with patch("requests.post", return_value=mock_resp):
+            result = client.extract_facts("text", "")
+        assert result["fact"] == "FB"
+
+    def test_generic_code_block(self, client):
+        mock_resp = MagicMock()
+        mock_resp.json.return_value = {
+            "choices": [{"message": {"content": "```\n{\"fact\": \"FG\", \"key_entities\": [], \"key_dates\": []}\n```"}}]
+        }
+        mock_resp.raise_for_status.return_value = None
+        with patch("requests.post", return_value=mock_resp):
+            result = client.extract_facts("text", "")
+        assert result["fact"] == "FG"
+
+    def test_chunk_failure_continues(self, client):
+        long_text = "x" * 20000
+        mock_resp = MagicMock()
+        mock_resp.json.return_value = {
+            "choices": [{"message": {"content": '{"fact": "OK", "key_entities": [], "key_dates": []}'}}]
+        }
+        mock_resp.raise_for_status.return_value = None
+        call_count = [0]
+        def side_effect(*a, **kw):
+            call_count[0] += 1
+            if call_count[0] == 1:
+                raise Exception("fail")
+            return mock_resp
+        with patch("requests.post", side_effect=side_effect):
+            result = client.extract_facts(long_text, "")
+        assert "OK" in result["fact"]
+
+    def test_custom_prompt(self, client):
+        mock_resp = MagicMock()
+        mock_resp.json.return_value = {
+            "choices": [{"message": {"content": '{"fact": "X", "key_entities": [], "key_dates": []}'}}]
+        }
+        mock_resp.raise_for_status.return_value = None
+        captured = []
+        def side_effect(*a, **kw):
+            captured.append(kw.get("json", {}))
+            return mock_resp
+        with patch("requests.post", side_effect=side_effect):
+            client.extract_facts("text", "custom prompt text")
+        assert "custom prompt text" in captured[0]["messages"][0]["content"]
+
+
+class TestAIProcessor:
+    def test_extract_facts_from_text(self, ai_config):
+        mock_resp = MagicMock()
+        mock_resp.json.return_value = {
+            "choices": [{"message": {"content": '{"fact": "FA", "key_entities": ["E1"], "key_dates": []}'}}]
+        }
+        mock_resp.raise_for_status.return_value = None
+        with patch("requests.post", return_value=mock_resp):
+            proc = AIProcessor(ai_config)
+            result = proc.extract_facts_from_text("content")
+        assert result["fact"] == "FA"
+
+    def test_validate_model_supported(self, ai_config):
+        proc = AIProcessor(ai_config)
+        assert proc.validate_model_support("gpt-oss") is True
+        assert proc.validate_model_support("qwen3") is True
+
+    def test_validate_model_unsupported(self, ai_config):
+        proc = AIProcessor(ai_config)
+        assert proc.validate_model_support("unknown-model") is False
diff --git a/tests/test_api.py b/tests/test_api.py
new file mode 100644
index 0000000..2b2eefa
--- /dev/null
+++ b/tests/test_api.py
@@ -0,0 +1,157 @@
+"""Tests for api module."""
+
+import os
+import pytest
+from unittest.mock import patch, MagicMock
+
+from factsdb.config import DatabaseConfig
+
+
+@pytest.fixture
+def app(tmp_path, monkeypatch):
+    """Create a Flask test app with in-memory DB and mocked config."""
+    db_path = str(tmp_path / "test.db")
+    monkeypatch.setenv("DATABASE_PATH", db_path)
+    monkeypatch.setenv("AI_ENDPOINT_URL", "http://localhost:8000/v1")
+    monkeypatch.setenv("AI_ENDPOINT_TOKEN", "tok")
+    monkeypatch.setenv("FTP_USERNAME", "u")
+    monkeypatch.setenv("FTP_PASSWORD", "p")
+    monkeypatch.setenv("API_KEY", "test-key")
+    from factsdb.api import create_app
+    return create_app()
+
+
+@pytest.fixture
+def client(app):
+    return app.test_client()
+
+
+class TestHealth:
+    def test_health(self, client):
+        resp = client.get("/health")
+        assert resp.status_code == 200
+        data = resp.get_json()
+        assert data["status"] == "healthy"
+        assert data["service"] == "FactsDB"
+
+
+class TestVersion:
+    def test_version(self, client):
+        resp = client.get("/version")
+        assert resp.status_code == 200
+        data = resp.get_json()
+        assert "version" in data
+
+
+class TestGetTables:
+    def test_without_api_key(self, client):
+        resp = client.get("/tables")
+        assert resp.status_code == 401
+
+    def test_with_api_key(self, client):
+        resp = client.get("/tables", headers={"X-API-Key": "test-key"})
+        assert resp.status_code == 200
+        data = resp.get_json()
+        assert "tables" in data
+        assert "total_tables" in data
+
+
+class TestGetTableData:
+    def test_without_api_key(self, client):
+        resp = client.get("/tables/nonexistent")
+        assert resp.status_code == 401
+
+    def test_with_api_key(self, client):
+        resp = client.get("/tables/nonexistent", headers={"X-API-Key": "test-key"})
+        assert resp.status_code == 200
+        data = resp.get_json()
+        assert "facts" in data
+
+
+class TestQueryTable:
+    def test_without_api_key(self, client):
+        resp = client.post("/tables/t1/query")
+        assert resp.status_code == 401
+
+    def test_with_api_key(self, client):
+        resp = client.post(
+            "/tables/t1/query",
+            headers={"X-API-Key": "test-key"},
+            json={"query": "test"}
+        )
+        assert resp.status_code == 200
+
+
+class TestGetTableCount:
+    def test_without_api_key(self, client):
+        resp = client.get("/tables/t1/count")
+        assert resp.status_code == 401
+
+    def test_with_api_key(self, client):
+        resp = client.get("/tables/t1/count", headers={"X-API-Key": "test-key"})
+        assert resp.status_code == 200
+        data = resp.get_json()
+        assert "count" in data
+
+
+class TestGetFact:
+    def test_without_api_key(self, client):
+        resp = client.get("/fact/1")
+        assert resp.status_code == 401
+
+    def test_not_found(self, client):
+        resp = client.get("/fact/999", headers={"X-API-Key": "test-key"})
+        assert resp.status_code == 404
+
+
+class TestSearch:
+    def test_without_api_key(self, client):
+        resp = client.get("/search")
+        assert resp.status_code == 401
+
+    def test_missing_query(self, client):
+        resp = client.get("/search", headers={"X-API-Key": "test-key"})
+        assert resp.status_code == 400
+
+    def test_with_query(self, client):
+        resp = client.get("/search?q=test", headers={"X-API-Key": "test-key"})
+        assert resp.status_code == 200
+
+
+class TestMetrics:
+    def test_metrics_prometheus(self, client):
+        resp = client.get("/metrics")
+        assert resp.status_code == 200
+
+    def test_metrics_json(self, client):
+        resp = client.get("/metrics/json")
+        assert resp.status_code == 200
+        data = resp.get_json()
+        assert "metrics" in data
+
+
+class TestStats:
+    def test_without_api_key(self, client):
+        resp = client.get("/stats")
+        assert resp.status_code == 401
+
+    def test_with_api_key(self, client):
+        resp = client.get("/stats", headers={"X-API-Key": "test-key"})
+        assert resp.status_code == 200
+
+
+class TestNoApiKeyRequired:
+    """Test endpoints that work when API_KEY env var is empty."""
+    def test_tables_open(self, tmp_path, monkeypatch):
+        db_path = str(tmp_path / "test.db")
+        monkeypatch.setenv("DATABASE_PATH", db_path)
+        monkeypatch.setenv("AI_ENDPOINT_URL", "http://localhost:8000/v1")
+        monkeypatch.setenv("AI_ENDPOINT_TOKEN", "tok")
+        monkeypatch.setenv("FTP_USERNAME", "u")
+        monkeypatch.setenv("FTP_PASSWORD", "p")
+        monkeypatch.setenv("API_KEY", "")
+        from factsdb.api import create_app
+        app = create_app()
+        c = app.test_client()
+        resp = c.get("/tables")
+        assert resp.status_code == 200
diff --git a/tests/test_api_errors.py b/tests/test_api_errors.py
new file mode 100644
index 0000000..94e4b9d
--- /dev/null
+++ b/tests/test_api_errors.py
@@ -0,0 +1,173 @@
+"""Extended tests for api module error paths."""
+
+import os
+import pytest
+from unittest.mock import patch, MagicMock
+
+
+@pytest.fixture
+def app_with_data(tmp_path, monkeypatch):
+    """Create a Flask app with data for testing error paths."""
+    db_path = str(tmp_path / "test.db")
+    monkeypatch.setenv("DATABASE_PATH", db_path)
+    monkeypatch.setenv("AI_ENDPOINT_URL", "http://localhost:8000/v1")
+    monkeypatch.setenv("AI_ENDPOINT_TOKEN", "tok")
+    monkeypatch.setenv("FTP_USERNAME", "u")
+    monkeypatch.setenv("FTP_PASSWORD", "p")
+    monkeypatch.setenv("API_KEY", "test-key")
+    from factsdb.api import create_app
+    from factsdb.database import DatabaseManager
+    from factsdb.config import DatabaseConfig
+    app = create_app()
+    # Insert some data for testing
+    db_cfg = DatabaseConfig(path=db_path)
+    dm = DatabaseManager(db_cfg)
+    dm.create_table("test_table")
+    dm.insert_fact("test_table", {
+        "fact": "Apple released the iPhone in 2007",
+        "key_entities": ["Apple", "iPhone"],
+        "key_dates": ["2007"],
+    })
+    yield app
+
+
+@pytest.fixture
+def client_with_data(app_with_data):
+    return app_with_data.test_client()
+
+
+class TestApiErrorPaths:
+    def test_tables_returns_data(self, client_with_data):
+        resp = client_with_data.get("/tables", headers={"X-API-Key": "test-key"})
+        assert resp.status_code == 200
+        data = resp.get_json()
+        assert "test_table" in [t["name"] for t in data["tables"]]
+
+    def test_table_data_returns_facts(self, client_with_data):
+        resp = client_with_data.get("/tables/test_table", headers={"X-API-Key": "test-key"})
+        assert resp.status_code == 200
+        data = resp.get_json()
+        assert len(data["facts"]) >= 1
+
+    def test_stats_returns_data(self, client_with_data):
+        resp = client_with_data.get("/stats", headers={"X-API-Key": "test-key"})
+        assert resp.status_code == 200
+        data = resp.get_json()
+        assert "database_stats" in data
+        assert "metrics" in data
+
+    def test_metrics_returns_text(self, client_with_data):
+        resp = client_with_data.get("/metrics")
+        assert resp.status_code == 200
+        assert "text/plain" in resp.content_type
+
+    def test_metrics_json_returns_data(self, client_with_data):
+        resp = client_with_data.get("/metrics/json")
+        assert resp.status_code == 200
+
+
+class TestApiExceptionPaths:
+    """Test that API properly returns 500 on database exceptions."""
+    def test_tables_error(self, tmp_path, monkeypatch):
+        db_path = str(tmp_path / "test.db")
+        monkeypatch.setenv("DATABASE_PATH", db_path)
+        monkeypatch.setenv("AI_ENDPOINT_URL", "http://localhost:8000/v1")
+        monkeypatch.setenv("AI_ENDPOINT_TOKEN", "tok")
+        monkeypatch.setenv("FTP_USERNAME", "u")
+        monkeypatch.setenv("FTP_PASSWORD", "p")
+        monkeypatch.setenv("API_KEY", "test-key")
+        from factsdb.api import create_app
+        app = create_app()
+        with app.app_context():
+            import sqlite3
+            conn = sqlite3.connect(db_path)
+            conn.execute("DROP TABLE tables")
+            conn.commit()
+            conn.close()
+            with app.test_client() as c:
+                resp = c.get("/tables", headers={"X-API-Key": "test-key"})
+                assert resp.status_code == 500
+
+    def test_table_data_error(self, tmp_path, monkeypatch):
+        db_path = str(tmp_path / "test.db")
+        monkeypatch.setenv("DATABASE_PATH", db_path)
+        monkeypatch.setenv("AI_ENDPOINT_URL", "http://localhost:8000/v1")
+        monkeypatch.setenv("AI_ENDPOINT_TOKEN", "tok")
+        monkeypatch.setenv("FTP_USERNAME", "u")
+        monkeypatch.setenv("FTP_PASSWORD", "p")
+        monkeypatch.setenv("API_KEY", "test-key")
+        from factsdb.api import create_app
+        app = create_app()
+        with app.app_context():
+            import sqlite3
+            conn = sqlite3.connect(db_path)
+            conn.execute("DROP TABLE facts")
+            conn.commit()
+            conn.close()
+            with app.test_client() as c:
+                resp = c.get("/tables/t1", headers={"X-API-Key": "test-key"})
+                assert resp.status_code == 500
+
+    def test_query_table_error(self, tmp_path, monkeypatch):
+        db_path = str(tmp_path / "test.db")
+        monkeypatch.setenv("DATABASE_PATH", db_path)
+        monkeypatch.setenv("AI_ENDPOINT_URL", "http://localhost:8000/v1")
+        monkeypatch.setenv("AI_ENDPOINT_TOKEN", "tok")
+        monkeypatch.setenv("FTP_USERNAME", "u")
+        monkeypatch.setenv("FTP_PASSWORD", "p")
+        monkeypatch.setenv("API_KEY", "test-key")
+        from factsdb.api import create_app
+        app = create_app()
+        with app.app_context():
+            import sqlite3
+            conn = sqlite3.connect(db_path)
+            conn.execute("DROP TABLE facts")
+            conn.commit()
+            conn.close()
+            with app.test_client() as c:
+                resp = c.post(
+                    "/tables/t1/query",
+                    headers={"X-API-Key": "test-key"},
+                    json={"query": "x"}
+                )
+                assert resp.status_code == 500
+
+    def test_table_count_error(self, tmp_path, monkeypatch):
+        db_path = str(tmp_path / "test.db")
+        monkeypatch.setenv("DATABASE_PATH", db_path)
+        monkeypatch.setenv("AI_ENDPOINT_URL", "http://localhost:8000/v1")
+        monkeypatch.setenv("AI_ENDPOINT_TOKEN", "tok")
+        monkeypatch.setenv("FTP_USERNAME", "u")
+        monkeypatch.setenv("FTP_PASSWORD", "p")
+        monkeypatch.setenv("API_KEY", "test-key")
+        from factsdb.api import create_app
+        app = create_app()
+        with app.app_context():
+            import sqlite3
+            conn = sqlite3.connect(db_path)
+            conn.execute("DROP TABLE facts")
+            conn.commit()
+            conn.close()
+            with app.test_client() as c:
+                resp = c.get("/tables/t1/count", headers={"X-API-Key": "test-key"})
+                assert resp.status_code == 500
+
+    def test_search_error(self, tmp_path, monkeypatch):
+        db_path = str(tmp_path / "test.db")
+        monkeypatch.setenv("DATABASE_PATH", db_path)
+        monkeypatch.setenv("AI_ENDPOINT_URL", "http://localhost:8000/v1")
+        monkeypatch.setenv("AI_ENDPOINT_TOKEN", "tok")
+        monkeypatch.setenv("FTP_USERNAME", "u")
+        monkeypatch.setenv("FTP_PASSWORD", "p")
+        monkeypatch.setenv("API_KEY", "test-key")
+        from factsdb.api import create_app
+        app = create_app()
+        with app.app_context():
+            import sqlite3
+            conn = sqlite3.connect(db_path)
+            conn.execute("DROP TABLE tables")
+            conn.commit()
+            conn.close()
+            with app.test_client() as c:
+                resp = c.get("/search?q=test", headers={"X-API-Key": "test-key"})
+                assert resp.status_code == 500
diff --git a/tests/test_config.py b/tests/test_config.py
new file mode 100644
index 0000000..a471560
--- /dev/null
+++ b/tests/test_config.py
@@ -0,0 +1,110 @@
+"""Tests for config module."""
+
+import os
+import pytest
+
+from factsdb.config import Config, DatabaseConfig, AIEndpointConfig, FTPServerConfig, SchedulerConfig
+
+
+class TestDatabaseConfig:
+    def test_default_path(self):
+        cfg = DatabaseConfig()
+        assert cfg.path == "./facts.db"
+
+    def test_custom_path(self):
+        cfg = DatabaseConfig(path="/tmp/test.db")
+        assert cfg.path == "/tmp/test.db"
+
+
+class TestAIEndpointConfig:
+    def test_defaults(self):
+        cfg = AIEndpointConfig()
+        assert cfg.url == ""
+        assert cfg.auth_token == ""
+
+    def test_custom_values(self):
+        cfg = AIEndpointConfig(url="http://example.com", auth_token="tok")
+        assert cfg.url == "http://example.com"
+        assert cfg.auth_token == "tok"
+
+
+class TestFTPServerConfig:
+    def test_defaults(self):
+        cfg = FTPServerConfig()
+        assert cfg.host == "0.0.0.0"
+        assert cfg.port == 2121
+        assert cfg.username == ""
+        assert cfg.password == ""
+
+    def test_custom_values(self):
+        cfg = FTPServerConfig(host="127.0.0.1", port=2122, username="u", password="p")
+        assert cfg.host == "127.0.0.1"
+        assert cfg.port == 2122
+        assert cfg.username == "u"
+        assert cfg.password == "p"
+
+
+class TestSchedulerConfig:
+    def test_default_interval(self):
+        cfg = SchedulerConfig()
+        assert cfg.interval_minutes == 10
+
+    def test_custom_interval(self):
+        cfg = SchedulerConfig(interval_minutes=5)
+        assert cfg.interval_minutes == 5
+
+
+class TestConfig:
+    def test_raises_missing_ai_token(self, monkeypatch):
+        monkeypatch.delenv("AI_ENDPOINT_TOKEN", raising=False)
+        monkeypatch.setenv("AI_ENDPOINT_URL", "http://x")
+        monkeypatch.delenv("FTP_USERNAME", raising=False)
+        monkeypatch.delenv("FTP_PASSWORD", raising=False)
+        with pytest.raises(ValueError, match="AI_ENDPOINT_TOKEN"):
+            Config()
+
+    def test_raises_missing_ai_url(self, monkeypatch):
+        monkeypatch.setenv("AI_ENDPOINT_TOKEN", "tok")
+        monkeypatch.delenv("AI_ENDPOINT_URL", raising=False)
+        monkeypatch.delenv("FTP_USERNAME", raising=False)
+        monkeypatch.delenv("FTP_PASSWORD", raising=False)
+        with pytest.raises(ValueError, match="AI_ENDPOINT_URL"):
+            Config()
+
+    def test_raises_missing_ftp_username(self, monkeypatch):
+        monkeypatch.setenv("AI_ENDPOINT_TOKEN", "tok")
+        monkeypatch.setenv("AI_ENDPOINT_URL", "http://x")
+        monkeypatch.delenv("FTP_USERNAME", raising=False)
+        monkeypatch.setenv("FTP_PASSWORD", "p")
+        with pytest.raises(ValueError, match="FTP_USERNAME"):
+            Config()
+
+    def test_raises_missing_ftp_password(self, monkeypatch):
+        monkeypatch.setenv("AI_ENDPOINT_TOKEN", "tok")
+        monkeypatch.setenv("AI_ENDPOINT_URL", "http://x")
+        monkeypatch.setenv("FTP_USERNAME", "u")
+        monkeypatch.delenv("FTP_PASSWORD", raising=False)
+        with pytest.raises(ValueError, match="FTP_PASSWORD"):
+            Config()
+
+    def test_full_config(self, monkeypatch, tmp_path):
+        db_path = str(tmp_path / "test.db")
+        monkeypatch.setenv("DATABASE_PATH", db_path)
+        monkeypatch.setenv("AI_ENDPOINT_URL", "http://ai.test")
+        monkeypatch.setenv("AI_ENDPOINT_TOKEN", "secret")
+        monkeypatch.setenv("FTP_USERNAME", "user")
+        monkeypatch.setenv("FTP_PASSWORD", "pass")
+        monkeypatch.setenv("FTP_HOST", "127.0.0.1")
+        monkeypatch.setenv("FTP_PORT", "2122")
+        monkeypatch.setenv("SCHEDULER_INTERVAL", "5")
+
+        cfg = Config()
+
+        assert cfg.database.path == db_path
+        assert cfg.ai_endpoint.url == "http://ai.test"
+        assert cfg.ai_endpoint.auth_token == "secret"
+        assert cfg.ftp_server.host == "127.0.0.1"
+        assert cfg.ftp_server.port == 2122
+        assert cfg.ftp_server.username == "user"
+        assert cfg.ftp_server.password == "pass"
+        assert cfg.scheduler.interval_minutes == 5
diff --git a/tests/test_database.py b/tests/test_database.py
new file mode 100644
index 0000000..ecc61e0
--- /dev/null
+++ b/tests/test_database.py
@@ -0,0 +1,219 @@
+"""Tests for database module."""
+
+import json
+import os
+import tempfile
+import pytest
+
+from factsdb.database import DatabaseManager, get_db_manager
+from factsdb.config import DatabaseConfig
+
+
+@pytest.fixture
+def db_manager(tmp_path):
+    """Create a DatabaseManager with a temp database."""
+    db_path = str(tmp_path / "test.db")
+    config = DatabaseConfig(path=db_path)
+    return DatabaseManager(config)
+
+
+class TestDatabaseManagerInit:
+    def test_creates_tables(self, db_manager):
+        tables = db_manager.get_table_names()
+        assert tables == []
+
+    def test_creates_db_file(self, tmp_path):
+        db_path = str(tmp_path / "init.db")
+        config = DatabaseConfig(path=db_path)
+        DatabaseManager(config)
+        assert os.path.exists(db_path)
+
+    def test_init_in_subdir(self, tmp_path):
+        subdir = tmp_path / "sub"
+        subdir.mkdir()
+        db_path = str(subdir / "test.db")
+        config = DatabaseConfig(path=db_path)
+        mgr = DatabaseManager(config)
+        assert mgr is not None
+
+
+class TestConnection:
+    def test_get_connection(self, db_manager):
+        with db_manager.get_connection() as conn:
+            cur = conn.execute("SELECT 1")
+            assert cur.fetchone()[0] == 1
+
+
+class CreateTableTests:
+    def test_create_table(self, db_manager):
+        db_manager.create_table("test_table")
+        names = db_manager.get_table_names()
+        assert "test_table" in names
+
+    def test_create_table_idempotent(self, db_manager):
+        db_manager.create_table("t1")
+        db_manager.create_table("t1")
+        names = db_manager.get_table_names()
+        assert names.count("t1") == 1
+
+
+class TestGetTableInfo:
+    def test_existing_table(self, db_manager):
+        db_manager.create_table("info_test")
+        info = db_manager.get_table_info("info_test")
+        assert info is not None
+        assert info["name"] == "info_test"
+        assert info["record_count"] == 0
+
+    def test_nonexistent_table(self, db_manager):
+        info = db_manager.get_table_info("no_such")
+        assert info is None
+
+
+class TestUpdateTableCount:
+    def test_update_count(self, db_manager):
+        db_manager.create_table("cnt")
+        db_manager.update_table_count("cnt", 42)
+        info = db_manager.get_table_info("cnt")
+        assert info["record_count"] == 42
+
+
+class TestInsertFact:
+    def test_insert_returns_id(self, db_manager):
+        db_manager.create_table("ft")
+        fid = db_manager.insert_fact("ft", {"fact": "F1", "key_entities": [], "key_dates": []})
+        assert fid > 0
+
+    def test_insert_stores_data(self, db_manager):
+        db_manager.create_table("ft")
+        db_manager.insert_fact("ft", {"fact": "F1", "key_entities": ["A"], "key_dates": ["2024-01-01"], "file_path": "/x"})
+        facts = db_manager.get_facts("ft")
+        assert len(facts) == 1
+        assert facts[0]["fact"] == "F1"
+        assert facts[0]["key_entities"] == ["A"]
+        assert facts[0]["key_dates"] == ["2024-01-01"]
+
+    def test_insert_updates_count(self, db_manager):
+        db_manager.create_table("ft")
+        db_manager.insert_fact("ft", {"fact": "F1"})
+        count = db_manager.get_table_count("ft")
+        assert count == 1
+
+
+class TestGetFacts:
+    def test_empty(self, db_manager):
+        db_manager.create_table("ft")
+        assert db_manager.get_facts("ft") == []
+
+    def test_limit(self, db_manager):
+        db_manager.create_table("ft")
+        for i in range(5):
+            db_manager.insert_fact("ft", {"fact": f"F{i}"})
+        facts = db_manager.get_facts("ft", limit=2)
+        assert len(facts) == 2
+
+    def test_offset(self, db_manager):
+        db_manager.create_table("ft")
+        for i in range(5):
+            db_manager.insert_fact("ft", {"fact": f"F{i}"})
+        facts = db_manager.get_facts("ft", limit=10, offset=3)
+        assert len(facts) == 2
+
+    def test_json_decode_error(self, db_manager):
+        db_manager.create_table("ft")
+        db_manager.insert_fact("ft", {"fact": "F1", "key_entities": ["e"]})
+        with db_manager.get_connection() as conn:
+            conn.execute("UPDATE facts SET key_entities = 'bad' WHERE id = 1")
+            conn.commit()
+        facts = db_manager.get_facts("ft")
+        assert facts[0]["key_entities"] == []
+
+
+class TestGetFactById:
+    def test_existing(self, db_manager):
+        db_manager.create_table("ft")
+        fid = db_manager.insert_fact("ft", {"fact": "F1"})
+        fact = db_manager.get_fact_by_id(fid)
+        assert fact is not None
+        assert fact["fact"] == "F1"
+
+    def test_nonexistent(self, db_manager):
+        assert db_manager.get_fact_by_id(999) is None
+
+
+class TestGetAllTables:
+    def test_multiple_tables(self, db_manager):
+        db_manager.create_table("a")
+        db_manager.create_table("b")
+        tables = db_manager.get_all_tables()
+        names = [t["name"] for t in tables]
+        assert "a" in names
+        assert "b" in names
+
+
+class TestFileTracking:
+    def test_mark_processed(self, db_manager):
+        db_manager.mark_file_processed("/path/file.txt", "ft", True)
+        assert db_manager.is_file_processed("/path/file.txt")
+
+    def test_mark_not_processed(self, db_manager):
+        db_manager.mark_file_processed("/path/file.txt", "ft", False, "err")
+        assert not db_manager.is_file_processed("/path/file.txt")
+
+    def test_unprocessed_file(self, db_manager):
+        assert db_manager.is_file_processed("/no/file") is False
+
+    def test_get_processed_files(self, db_manager):
+        db_manager.mark_file_processed("/a", "ft", True)
+        db_manager.mark_file_processed("/b", "ft", False)
+        processed = db_manager.get_processed_files("ft")
+        assert "/a" in processed
+        assert "/b" not in processed
+
+    def test_get_unprocessed_files(self, db_manager):
+        db_manager.mark_file_processed("/a", "ft", True)
+        db_manager.mark_file_processed("/b", "ft", False)
+        unprocessed = db_manager.get_unprocessed_files("ft")
+        assert "/b" in unprocessed
+        assert "/a" not in unprocessed
+
+
+class TestQueryAndAliases:
+    def test_query_table(self, db_manager):
+        db_manager.create_table("ft")
+        db_manager.insert_fact("ft", {"fact": "F1"})
+        results = db_manager.query_table("ft")
+        assert len(results) == 1
+
+    def test_get_table_record_count(self, db_manager):
+        db_manager.create_table("ft")
+        db_manager.insert_fact("ft", {"fact": "F1"})
+        assert db_manager.get_table_record_count("ft") == 1
+
+    def test_store_fact(self, db_manager):
+        db_manager.create_table("ft")
+        fid = db_manager.store_fact({"fact": "F1"}, "ft", "/x")
+        assert fid > 0
+
+
+class TestDatabaseStats:
+    def test_stats(self, db_manager):
+        db_manager.create_table("ft")
+        db_manager.insert_fact("ft", {"fact": "F1"})
+        db_manager.mark_file_processed("/a", "ft", True)
+        stats = db_manager.get_database_stats()
+        assert stats["total_facts"] == 1
+        assert stats["processed_files"] == 1
+        assert "ft" in stats["table_counts"]
+
+
+class TestGetDbManager:
+    def test_singleton(self, tmp_path, monkeypatch):
+        import factsdb.database as db_module
+        db_module._db_manager = None
+        db_path = str(tmp_path / "sg.db")
+        config = DatabaseConfig(path=db_path)
+        m1 = get_db_manager(config)
+        m2 = get_db_manager(config)
+        assert m1 is m2
+        db_module._db_manager = None
diff --git a/tests/test_database_ext.py b/tests/test_database_ext.py
new file mode 100644
index 0000000..a23ae60
--- /dev/null
+++ b/tests/test_database_ext.py
@@ -0,0 +1,76 @@
+"""Extended tests for database error paths."""
+
+import os
+import pytest
+import sqlite3
+import tempfile
+
+from factsdb.database import DatabaseManager
+from factsdb.config import DatabaseConfig
+
+
+class TestDatabaseInitError:
+    def test_init_readonly_path(self, tmp_path, monkeypatch):
+        """Test that database init handles permission errors gracefully."""
+        ro_dir = tmp_path / "readonly"
+        ro_dir.mkdir()
+        ro_dir.chmod(0o000)
+        db_path = str(ro_dir / "test.db")
+        config = DatabaseConfig(path=db_path)
+        try:
+            with pytest.raises(Exception):
+                DatabaseManager(config)
+        finally:
+            ro_dir.chmod(0o755)
+
+    def test_init_creates_dir(self, tmp_path):
+        """Test that database init creates parent directory."""
+        subdir = tmp_path / "new_sub"
+        subdir.mkdir()
+        db_path = str(subdir / "test.db")
+        config = DatabaseConfig(path=db_path)
+        mgr = DatabaseManager(config)
+        assert mgr is not None
+
+
+class TestGetFactByIdJsonErrors:
+    def test_get_fact_bad_key_entities(self, tmp_path):
+        """Test get_fact_by_id handles bad JSON in key_entities."""
+        db_path = str(tmp_path / "test.db")
+        config = DatabaseConfig(path=db_path)
+        dm = DatabaseManager(config)
+        dm.create_table("t1")
+        dm.insert_fact("t1", {"fact": "F1", "key_entities": ["e"]})
+        with dm.get_connection() as conn:
+            conn.execute("UPDATE facts SET key_entities = 'bad_json' WHERE id = 1")
+            conn.commit()
+        fact = dm.get_fact_by_id(1)
+        assert fact is not None
+        assert fact["key_entities"] == []
+
+    def test_get_fact_bad_key_dates(self, tmp_path):
+        """Test get_fact_by_id handles bad JSON in key_dates."""
+        db_path = str(tmp_path / "test.db")
+        config = DatabaseConfig(path=db_path)
+        dm = DatabaseManager(config)
+        dm.create_table("t1")
+        dm.insert_fact("t1", {"fact": "F1", "key_dates": ["d"]})
+        with dm.get_connection() as conn:
+            conn.execute("UPDATE facts SET key_dates = 'bad_json' WHERE id = 1")
+            conn.commit()
+        fact = dm.get_fact_by_id(1)
+        assert fact is not None
+        assert fact["key_dates"] == []
+
+    def test_get_facts_bad_key_dates(self, tmp_path):
+        """Test get_facts handles bad JSON in key_dates."""
+        db_path = str(tmp_path / "test.db")
+        config = DatabaseConfig(path=db_path)
+        dm = DatabaseManager(config)
+        dm.create_table("t1")
+        dm.insert_fact("t1", {"fact": "F1", "key_dates": ["d"]})
+        with dm.get_connection() as conn:
+            conn.execute("UPDATE facts SET key_dates = 'bad_json' WHERE id = 1")
+            conn.commit()
+        facts = dm.get_facts("t1")
+        assert facts[0]["key_dates"] == []
diff --git a/tests/test_file_processor.py b/tests/test_file_processor.py
new file mode 100644
index 0000000..afb0844
--- /dev/null
+++ b/tests/test_file_processor.py
@@ -0,0 +1,114 @@
+"""Tests for file_processor module."""
+
+import os
+import pytest
+import tempfile
+import json
+
+from factsdb.file_processor import FileProcessor
+
+
+@pytest.fixture
+def processor():
+    return FileProcessor()
+
+
+class TestDetectFileType:
+    def test_txt(self, processor):
+        assert processor.detect_file_type("file.txt") == "txt"
+
+    def test_html(self, processor):
+        assert processor.detect_file_type("page.html") == "html"
+
+    def test_htm(self, processor):
+        assert processor.detect_file_type("page.htm") == "htm"
+
+    def test_pdf(self, processor):
+        assert processor.detect_file_type("doc.pdf") == "pdf"
+
+    def test_json(self, processor):
+        assert processor.detect_file_type("data.json") == "json"
+
+    def test_xml(self, processor):
+        assert processor.detect_file_type("data.xml") == "xml"
+
+    def test_uppercase(self, processor):
+        assert processor.detect_file_type("file.TXT") == "txt"
+
+    def test_no_extension(self, processor):
+        assert processor.detect_file_type("file") == ""
+
+
+class TestIsSupportedFileType:
+    def test_supported(self, processor, tmp_path):
+        for ext in ["txt", "md", "log", "html", "htm", "pdf", "xml", "json"]:
+            f = tmp_path / f"file.{ext}"
+            f.touch()
+            assert processor.is_supported_file_type(str(f)) is True
+
+    def test_unsupported(self, processor, tmp_path):
+        f = tmp_path / "file.xyz"
+        f.touch()
+        assert processor.is_supported_file_type(str(f)) is False
+
+
+class TestExtractTextFromFile:
+    def test_text_file(self, processor, tmp_path):
+        f = tmp_path / "test.txt"
+        f.write_text("Hello World")
+        assert processor.extract_text_from_file(str(f)) == "Hello World"
+
+    def test_html_file(self, processor, tmp_path):
+        f = tmp_path / "test.html"
+        f.write_text("<html><body><p>Hello</p></body></html>")
+        text = processor.extract_text_from_file(str(f))
+        assert "Hello" in text
+
+    def test_json_file(self, processor, tmp_path):
+        f = tmp_path / "test.json"
+        data = {"key": "value"}
+        f.write_text(json.dumps(data))
+        text = processor.extract_text_from_file(str(f))
+        assert "key" in text
+
+    def test_unsupported_type(self, processor, tmp_path):
+        f = tmp_path / "test.xyz"
+        f.write_text("x")
+        with pytest.raises(Exception, match="Unsupported file type"):
+            processor.extract_text_from_file(str(f))
+
+    def test_nonexistent_file(self, processor):
+        with pytest.raises(Exception):
+            processor.extract_text_from_file("/nonexistent/path/file.txt")
+
+
+class TestHtmlExtraction:
+    def test_removes_scripts(self, processor, tmp_path):
+        f = tmp_path / "test.html"
+        f.write_text("<html><script>alert(1)</script><p>Content</p></html>")
+        text = processor.extract_text_from_file(str(f))
+        assert "alert" not in text
+        assert "Content" in text
+
+    def test_removes_styles(self, processor, tmp_path):
+        f = tmp_path / "test.html"
+        f.write_text("<html><style>body{}</style><p>Content</p></html>")
+        text = processor.extract_text_from_file(str(f))
+        assert "Content" in text
+
+
+class TestGetFileInfo:
+    def test_basic_info(self, processor, tmp_path):
+        f = tmp_path / "test.txt"
+        f.write_text("hello")
+        info = processor.get_file_info(str(f))
+        assert info["name"] == "test.txt"
+        assert info["type"] == "txt"
+        assert info["is_supported"] is True
+        assert info["size"] == 5
+
+    def test_unsupported_info(self, processor, tmp_path):
+        f = tmp_path / "test.xyz"
+        f.write_text("hello")
+        info = processor.get_file_info(str(f))
+        assert info["is_supported"] is False
diff --git a/tests/test_file_processor_ext.py b/tests/test_file_processor_ext.py
new file mode 100644
index 0000000..b9be669
--- /dev/null
+++ b/tests/test_file_processor_ext.py
@@ -0,0 +1,41 @@
+"""Extended tests for file_processor: PDF, XML extraction."""
+
+import pytest
+from unittest.mock import patch, MagicMock
+
+from factsdb.file_processor import FileProcessor
+
+
+@pytest.fixture
+def processor():
+    return FileProcessor()
+
+
+class TestPdfExtraction:
+    def test_pdf_success(self, processor, tmp_path):
+        f = tmp_path / "test.pdf"
+        f.write_bytes(b"%PDF-1.4 fake pdf content")
+        with patch("pdfminer.high_level.extract_text", return_value="PDF content here"):
+            text = processor.extract_text_from_file(str(f))
+        assert text == "PDF content here"
+
+    def test_pdf_failure(self, processor, tmp_path):
+        f = tmp_path / "test.pdf"
+        f.write_bytes(b"%PDF-1.4 fake pdf content")
+        with patch("pdfminer.high_level.extract_text", side_effect=Exception("parse error")):
+            with pytest.raises(Exception, match="PDF extraction failed"):
+                processor.extract_text_from_file(str(f))
+
+
+class TestXmlExtraction:
+    def test_xml_file(self, processor, tmp_path):
+        f = tmp_path / "test.xml"
+        f.write_text("<root><item>Hello</item></root>")
+        text = processor.extract_text_from_file(str(f))
+        assert "Hello" in text
+
+    def test_json_invalid(self, processor, tmp_path):
+        f = tmp_path / "test.json"
+        f.write_text("{invalid json")
+        text = processor.extract_text_from_file(str(f))
+        assert "invalid json" in text
diff --git a/tests/test_ftp_server.py b/tests/test_ftp_server.py
new file mode 100644
index 0000000..f427ded
--- /dev/null
+++ b/tests/test_ftp_server.py
@@ -0,0 +1,99 @@
+"""Tests for ftp_server module."""
+
+import pytest
+from unittest.mock import patch, MagicMock
+
+
+@pytest.fixture(autouse=True)
+def mock_pyftpdlib():
+    """Mock pyftpdlib modules which are not available on Python 3.12+."""
+    with patch.dict("sys.modules", {
+        "pyftpdlib": MagicMock(),
+        "pyftpdlib.authorizers": MagicMock(),
+        "pyftpdlib.handlers": MagicMock(),
+        "pyftpdlib.servers": MagicMock(),
+    }):
+        from factsdb.ftp_server import FTPServerManager, get_ftp_server_manager
+        yield
+
+
+class MockConfig:
+    """Lightweight mock Config for FTP tests."""
+
+    def __init__(self):
+        self.ftp_server = MagicMock()
+        self.ftp_server.host = "0.0.0.0"
+        self.ftp_server.port = 2121
+        self.ftp_server.username = "testuser"
+        self.ftp_server.password = "testpass"
+        self.database = MagicMock()
+
+
+class TestFTPServerManager:
+    def test_init(self, mock_pyftpdlib):
+        from factsdb.ftp_server import FTPServerManager
+        mgr = FTPServerManager(MockConfig())
+        assert mgr.is_running is False
+        assert mgr.onboarded_directories == set()
+        assert mgr.server is None
+
+    def test_add_onboarded_directory(self, mock_pyftpdlib, tmp_path):
+        from factsdb.ftp_server import FTPServerManager
+        mgr = FTPServerManager(MockConfig())
+        mgr.add_onboarded_directory(str(tmp_path))
+        assert str(tmp_path) in mgr.onboarded_directories
+
+    def test_add_nonexistent_directory(self, mock_pyftpdlib, tmp_path):
+        from factsdb.ftp_server import FTPServerManager
+        mgr = FTPServerManager(MockConfig())
+        mgr.add_onboarded_directory("/nonexistent/path")
+        assert len(mgr.onboarded_directories) == 0
+
+    def test_is_directory_allowed(self, mock_pyftpdlib, tmp_path):
+        from factsdb.ftp_server import FTPServerManager
+        mgr = FTPServerManager(MockConfig())
+        mgr.add_onboarded_directory(str(tmp_path))
+        assert mgr.is_directory_allowed(str(tmp_path)) is True
+        assert mgr.is_directory_allowed("/other/path") is False
+
+    def test_is_directory_subpath(self, mock_pyftpdlib, tmp_path):
+        from factsdb.ftp_server import FTPServerManager
+        mgr = FTPServerManager(MockConfig())
+        mgr.add_onboarded_directory(str(tmp_path))
+        sub = tmp_path / "sub"
+        assert mgr.is_directory_allowed(str(sub)) is True
+
+    def test_get_onboarded_directories(self, mock_pyftpdlib, tmp_path):
+        from factsdb.ftp_server import FTPServerManager
+        mgr = FTPServerManager(MockConfig())
+        mgr.add_onboarded_directory(str(tmp_path))
+        dirs = mgr.get_onboarded_directories()
+        assert len(dirs) == 1
+        assert str(tmp_path) in dirs
+
+    def test_is_running_attr(self, mock_pyftpdlib):
+        from factsdb.ftp_server import FTPServerManager
+        mgr = FTPServerManager(MockConfig())
+        assert mgr.is_running is False
+
+
+class TestFTPServerStartStop:
+    def test_start_already_running(self, mock_pyftpdlib):
+        from factsdb.ftp_server import FTPServerManager
+        mgr = FTPServerManager(MockConfig())
+        mgr.is_running = True
+        mgr.server = MagicMock()
+        mgr.start()
+        assert mgr.is_running is True
+
+
+class TestGetFtpServerManager:
+    def test_singleton(self, mock_pyftpdlib):
+        from factsdb import ftp_server as ftp_mod
+        ftp_mod._ftp_server_manager = None
+        from factsdb.ftp_server import FTPServerManager, get_ftp_server_manager
+        cfg = MockConfig()
+        m1 = get_ftp_server_manager(cfg)
+        m2 = get_ftp_server_manager(cfg)
+        assert m1 is m2
+        ftp_mod._ftp_server_manager = None
diff --git a/tests/test_ftp_server_ext.py b/tests/test_ftp_server_ext.py
new file mode 100644
index 0000000..5cf8bca
--- /dev/null
+++ b/tests/test_ftp_server_ext.py
@@ -0,0 +1,73 @@
+"""Extended tests for ftp_server: start/stop logic."""
+
+import pytest
+from unittest.mock import patch, MagicMock
+
+
+@pytest.fixture(autouse=True)
+def mock_pyftpdlib():
+    """Mock pyftpdlib for all FTP tests."""
+    with patch.dict("sys.modules", {
+        "pyftpdlib": MagicMock(),
+        "pyftpdlib.authorizers": MagicMock(),
+        "pyftpdlib.handlers": MagicMock(),
+        "pyftpdlib.servers": MagicMock(),
+    }):
+        yield
+
+
+class MockConfig:
+    def __init__(self):
+        self.ftp_server = MagicMock()
+        self.ftp_server.host = "0.0.0.0"
+        self.ftp_server.port = 2121
+        self.ftp_server.username = "testuser"
+        self.ftp_server.password = "testpass"
+        self.database = MagicMock()
+
+
+class TestFtpStartStop:
+    def test_start_success(self, mock_pyftpdlib):
+        from factsdb.ftp_server import FTPServerManager
+        cfg = MockConfig()
+        mgr = FTPServerManager(cfg)
+        with patch.object(mgr, "_run_server"):
+            mgr.start()
+        assert mgr.is_running is True
+        assert mgr.server is not None
+        mgr.stop()
+
+    def test_stop(self, mock_pyftpdlib):
+        from factsdb.ftp_server import FTPServerManager
+        cfg = MockConfig()
+        mgr = FTPServerManager(cfg)
+        mgr.server = MagicMock()
+        mgr.is_running = True
+        mgr.stop()
+        assert mgr.is_running is False
+        mgr.server.close_all.assert_called_once()
+
+    def test_stop_no_server(self, mock_pyftpdlib):
+        from factsdb.ftp_server import FTPServerManager
+        cfg = MockConfig()
+        mgr = FTPServerManager(cfg)
+        mgr.server = None
+        mgr.is_running = True
+        mgr.stop()
+        assert mgr.server is None
+
+    def test_run_server(self, mock_pyftpdlib):
+        from factsdb.ftp_server import FTPServerManager
+        cfg = MockConfig()
+        mgr = FTPServerManager(cfg)
+        mock_server = MagicMock()
+        mgr.server = mock_server
+        # Call serve_forever once then stop to avoid blocking
+        call_count = [0]
+        def mock_forever():
+            call_count[0] += 1
+            if call_count[0] > 1:
+                return
+        mock_server.serve_forever.side_effect = mock_forever
+        mgr._run_server()
+        assert call_count[0] >= 1
diff --git a/tests/test_monitoring.py b/tests/test_monitoring.py
new file mode 100644
index 0000000..6ea5d07
--- /dev/null
+++ b/tests/test_monitoring.py
@@ -0,0 +1,107 @@
+"""Tests for monitoring module."""
+
+import os
+import pytest
+import threading
+import time
+from unittest.mock import patch
+
+from factsdb.monitoring import (
+    increment_fact_extraction,
+    increment_file_processing,
+    increment_error,
+    get_metrics,
+    get_metrics_json,
+    start_uptime_monitor,
+    _metrics,
+    _metrics_lock,
+)
+from factsdb.config import DatabaseConfig
+
+
+def reset_metrics():
+    """Reset global metrics to known state."""
+    with _metrics_lock:
+        _metrics["fact_extraction_count"] = 0
+        _metrics["file_processing_count"] = 0
+        _metrics["error_count"] = 0
+        _metrics["last_extraction_time"] = 0
+        _metrics["uptime_seconds"] = 0
+
+
+@pytest.fixture(autouse=True)
+def clean_metrics():
+    reset_metrics()
+    yield
+    reset_metrics()
+
+
+class TestIncrementFactExtraction:
+    def test_increment(self):
+        increment_fact_extraction()
+        assert _metrics["fact_extraction_count"] == 1
+        assert _metrics["last_extraction_time"] > 0
+
+    def test_multiple(self):
+        for _ in range(3):
+            increment_fact_extraction()
+        assert _metrics["fact_extraction_count"] == 3
+
+
+class TestIncrementFileProcessing:
+    def test_increment(self):
+        increment_file_processing()
+        assert _metrics["file_processing_count"] == 1
+
+    def test_multiple(self):
+        for _ in range(5):
+            increment_file_processing()
+        assert _metrics["file_processing_count"] == 5
+
+
+class TestIncrementError:
+    def test_increment(self):
+        increment_error()
+        assert _metrics["error_count"] == 1
+
+
+class TestGetMetrics:
+    def test_prometheus_format(self, tmp_path, monkeypatch):
+        db_path = str(tmp_path / "mon.db")
+        monkeypatch.setenv("DATABASE_PATH", db_path)
+        monkeypatch.setenv("AI_ENDPOINT_URL", "http://localhost:8000/v1")
+        monkeypatch.setenv("AI_ENDPOINT_TOKEN", "tok")
+        monkeypatch.setenv("FTP_USERNAME", "u")
+        monkeypatch.setenv("FTP_PASSWORD", "p")
+        text = get_metrics()
+        assert "factsdb_fact_extractions_total" in text
+        assert "factsdb_files_processed_total" in text
+        assert "factsdb_errors_total" in text
+        assert "factsdb_uptime_seconds" in text
+
+
+class TestGetMetricsJson:
+    def test_json_format(self, tmp_path, monkeypatch):
+        db_path = str(tmp_path / "mon.db")
+        monkeypatch.setenv("DATABASE_PATH", db_path)
+        monkeypatch.setenv("AI_ENDPOINT_URL", "http://localhost:8000/v1")
+        monkeypatch.setenv("AI_ENDPOINT_TOKEN", "tok")
+        monkeypatch.setenv("FTP_USERNAME", "u")
+        monkeypatch.setenv("FTP_PASSWORD", "p")
+        data = get_metrics_json()
+        assert "metrics" in data
+        assert "timestamp" in data
+        assert "database_stats" in data
+        m = data["metrics"]
+        assert "fact_extractions" in m
+        assert "files_processed" in m
+        assert "errors" in m
+        assert "uptime_seconds" in m
+
+
+class TestStartUptimeMonitor:
+    def test_returns_thread(self):
+        thread = start_uptime_monitor()
+        assert isinstance(thread, threading.Thread)
+        assert thread.daemon is True
+        assert thread.is_alive()
diff --git a/tests/test_scheduler.py b/tests/test_scheduler.py
new file mode 100644
index 0000000..aefca93
--- /dev/null
+++ b/tests/test_scheduler.py
@@ -0,0 +1,98 @@
+"""Tests for scheduler module."""
+
+import os
+import pytest
+from unittest.mock import patch, MagicMock
+
+from factsdb.config import Config, DatabaseConfig, AIEndpointConfig, FTPServerConfig, SchedulerConfig
+from factsdb.scheduler import FactExtractionJob, FactExtractionScheduler, get_scheduler
+
+
+class MockConfig:
+    """Lightweight mock Config that avoids env var requirements."""
+
+    def __init__(self, db_path=":memory:"):
+        self.database = DatabaseConfig(path=db_path)
+        self.ai_endpoint = AIEndpointConfig(url="http://localhost", auth_token="tok")
+        self.ftp_server = FTPServerConfig(host="0.0.0.0", port=2121, username="u", password="p")
+        self.scheduler = SchedulerConfig(interval_minutes=10)
+
+
+@pytest.fixture
+def scheduler_config(tmp_path):
+    return MockConfig(db_path=str(tmp_path / "sched.db"))
+
+
+class TestFactExtractionJob:
+    def test_execute_missing_directory(self, scheduler_config):
+        from factsdb.database import DatabaseManager
+        from factsdb.file_processor import FileProcessor
+        from factsdb.ai_processor import AIProcessor
+        dm = DatabaseManager(scheduler_config.database)
+        fp = FileProcessor()
+        ap = AIProcessor(scheduler_config.ai_endpoint)
+        job = FactExtractionJob(scheduler_config, dm, fp, ap)
+        with pytest.raises(Exception, match="Directory does not exist"):
+            job.execute("/nonexistent/dir", "t", "", "gpt-oss")
+
+
+class TestFactExtractionScheduler:
+    def test_init(self, scheduler_config):
+        with patch("factsdb.scheduler.AIProcessor"):
+            with patch("factsdb.scheduler.DatabaseManager"):
+                sched = FactExtractionScheduler(scheduler_config)
+                assert sched.jobs == {}
+                assert sched.is_running is False
+
+    def test_add_job(self, scheduler_config):
+        with patch("factsdb.scheduler.AIProcessor"):
+            with patch("factsdb.scheduler.DatabaseManager"):
+                sched = FactExtractionScheduler(scheduler_config)
+                sched.add_job("/tmp", "t1", "", "gpt-oss", 5)
+                jobs = sched.get_jobs()
+                assert len(jobs) == 1
+                assert jobs[0]["directory_path"] == "/tmp"
+                assert jobs[0]["interval_minutes"] == 5
+
+    def test_remove_job(self, scheduler_config):
+        with patch("factsdb.scheduler.AIProcessor"):
+            with patch("factsdb.scheduler.DatabaseManager"):
+                sched = FactExtractionScheduler(scheduler_config)
+                sched.add_job("/tmp", "t1")
+                sched.remove_job("job_1")
+                assert len(sched.get_jobs()) == 0
+
+    def test_is_job_running(self, scheduler_config):
+        with patch("factsdb.scheduler.AIProcessor"):
+            with patch("factsdb.scheduler.DatabaseManager"):
+                sched = FactExtractionScheduler(scheduler_config)
+                sched.add_job("/tmp", "t1")
+                assert sched.is_job_running("job_1") is True
+                assert sched.is_job_running("job_99") is False
+
+    def test_start_stop(self, scheduler_config):
+        with patch("factsdb.scheduler.AIProcessor"):
+            with patch("factsdb.scheduler.DatabaseManager"):
+                sched = FactExtractionScheduler(scheduler_config)
+                sched.start()
+                assert sched.is_running is True
+                sched.stop()
+                assert sched.is_running is False
+
+    def test_get_jobs_empty(self, scheduler_config):
+        with patch("factsdb.scheduler.AIProcessor"):
+            with patch("factsdb.scheduler.DatabaseManager"):
+                sched = FactExtractionScheduler(scheduler_config)
+                assert sched.get_jobs() == []
+
+
+class TestGetScheduler:
+    def test_singleton(self, scheduler_config):
+        import factsdb.scheduler as sched_mod
+        sched_mod._scheduler = None
+        with patch("factsdb.scheduler.AIProcessor"):
+            with patch("factsdb.scheduler.DatabaseManager"):
+                s1 = get_scheduler(scheduler_config)
+                s2 = get_scheduler(scheduler_config)
+                assert s1 is s2
+                sched_mod._scheduler = None
diff --git a/tests/test_scheduler_ext.py b/tests/test_scheduler_ext.py
new file mode 100644
index 0000000..b804fb7
--- /dev/null
+++ b/tests/test_scheduler_ext.py
@@ -0,0 +1,130 @@
+"""Extended tests for scheduler: job execution flow."""
+
+import os
+import pytest
+from unittest.mock import patch, MagicMock
+
+from factsdb.config import DatabaseConfig, AIEndpointConfig, FTPServerConfig, SchedulerConfig
+
+
+class MockConfig:
+    def __init__(self, db_path=":memory:"):
+        self.database = DatabaseConfig(path=db_path)
+        self.ai_endpoint = AIEndpointConfig(url="http://localhost", auth_token="tok")
+        self.ftp_server = FTPServerConfig(host="0.0.0.0", port=2121, username="u", password="p")
+        self.scheduler = SchedulerConfig(interval_minutes=10)
+
+
+class TestFactExtractionJobExecute:
+    def test_execute_success(self, tmp_path):
+        from factsdb.scheduler import FactExtractionJob
+        from factsdb.database import DatabaseManager
+        from factsdb.file_processor import FileProcessor
+
+        cfg = MockConfig(db_path=str(tmp_path / "sched.db"))
+        dm = DatabaseManager(cfg.database)
+        fp = FileProcessor()
+
+        dm.create_table("t1")
+
+        # Create a test file
+        test_file = tmp_path / "test.txt"
+        test_file.write_text("Apple released the iPhone in 2007")
+
+        # Mock AI processor
+        mock_ai = MagicMock()
+        mock_ai.extract_facts_from_text.return_value = {
+            "fact": "Test fact",
+            "key_entities": ["Apple"],
+            "key_dates": ["2007"],
+        }
+
+        job = FactExtractionJob(cfg, dm, fp, mock_ai)
+        job.execute(str(tmp_path), "t1", "", "gpt-oss")
+
+        facts = dm.get_facts("t1")
+        assert len(facts) == 1
+        assert facts[0]["fact"] == "Test fact"
+
+    def test_execute_skip_processed(self, tmp_path):
+        from factsdb.scheduler import FactExtractionJob
+        from factsdb.database import DatabaseManager
+        from factsdb.file_processor import FileProcessor
+
+        cfg = MockConfig(db_path=str(tmp_path / "sched.db"))
+        dm = DatabaseManager(cfg.database)
+        fp = FileProcessor()
+        dm.create_table("t1")
+
+        test_file = tmp_path / "test.txt"
+        test_file.write_text("content")
+        dm.mark_file_processed(str(test_file), "t1", True)
+
+        mock_ai = MagicMock()
+        job = FactExtractionJob(cfg, dm, fp, mock_ai)
+        job.execute(str(tmp_path), "t1", "", "gpt-oss")
+
+        mock_ai.extract_facts_from_text.assert_not_called()
+
+    def test_execute_file_error_continues(self, tmp_path):
+        from factsdb.scheduler import FactExtractionJob
+        from factsdb.database import DatabaseManager
+        from factsdb.file_processor import FileProcessor
+
+        cfg = MockConfig(db_path=str(tmp_path / "sched.db"))
+        dm = DatabaseManager(cfg.database)
+        dm.create_table("t1")
+        fp = FileProcessor()
+
+        test_file = tmp_path / "test.txt"
+        test_file.write_text("content")
+
+        mock_ai = MagicMock()
+        mock_ai.extract_facts_from_text.side_effect = Exception("AI error")
+
+        job = FactExtractionJob(cfg, dm, fp, mock_ai)
+        job.execute(str(tmp_path), "t1", "", "gpt-oss")
+
+        facts = dm.get_facts("t1")
+        assert len(facts) == 0
+
+
+class TestSchedulerInitError:
+    def test_scheduler_db_init_error(self, tmp_path, monkeypatch):
+        from factsdb.scheduler import FactExtractionScheduler
+
+        cfg = MockConfig(db_path=str(tmp_path / "sched.db"))
+        with patch("factsdb.scheduler.AIProcessor"):
+            with patch("factsdb.scheduler.DatabaseManager", side_effect=Exception("db error")):
+                sched = FactExtractionScheduler(cfg)
+                assert sched.db_manager is None
+
+
+class TestSchedulerRunAllJobs:
+    def test_run_all_jobs(self, tmp_path, monkeypatch):
+        from factsdb.scheduler import FactExtractionScheduler
+        from factsdb.database import DatabaseManager
+
+        cfg = MockConfig(db_path=str(tmp_path / "sched.db"))
+        dm = DatabaseManager(cfg.database)
+        dm.create_table("t1")
+
+        test_file = tmp_path / "test.txt"
+        test_file.write_text("content")
+
+        with patch("factsdb.scheduler.AIProcessor") as mock_ai_cls:
+            mock_ai = MagicMock()
+            mock_ai.extract_facts_from_text.return_value = {
+                "fact": "F",
+                "key_entities": [],
+                "key_dates": [],
+            }
+            mock_ai_cls.return_value = mock_ai
+
+            with patch("factsdb.scheduler.DatabaseManager", return_value=dm):
+                sched = FactExtractionScheduler(cfg)
+                sched.add_job(str(tmp_path), "t1", "", "gpt-oss")
+                sched._run_all_jobs()
+
+        facts = dm.get_facts("t1")
+        assert len(facts) == 1