diff --git a/.github/workflows/ci-main.yml b/.github/workflows/ci-main.yml
new file mode 100644
index 0000000..f845888
--- /dev/null
+++ b/.github/workflows/ci-main.yml
@@ -0,0 +1,74 @@
+name: Main CI (full)
+on:
+  push:
+    branches: [ main ]
+
+jobs:
+  test-and-smoke:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - uses: actions/setup-python@v5
+        with:
+          python-version: '3.11'
+          cache: 'pip'
+          cache-dependency-path: |
+            requirements.txt
+            requirements-dev.txt
+
+      - name: Install deps
+        run: |
+          python -m pip install --upgrade pip
+          pip install -r requirements.txt -r requirements-dev.txt
+
+      - name: Unit tests
+        env:
+          PYTHONDONTWRITEBYTECODE: 1
+        run: |
+          python -m pytest --cov=serving_app --cov-report=term-missing
+
+      - name: Train model
+        run: python -m training.train
+
+      - name: Boot API
+        env:
+          API_KEY: test-key
+        run: |
+          set -euo pipefail
+          uvicorn serving_app.main:app --host 127.0.0.1 --port 8011 >/tmp/uvicorn.log 2>&1 &
+          echo $! > /tmp/uvicorn.pid
+          for i in {1..40}; do
+            if curl -sf http://127.0.0.1:8011/health >/dev/null; then
+              echo "API is up"
+              exit 0
+            fi
+            sleep 0.5
+          done
+          echo "API failed to start"; cat /tmp/uvicorn.log || true; exit 1
+
+      - name: Predict smoke (trained)
+        env:
+          API_KEY: test-key
+        run: |
+          set -euo pipefail
+          RESP=$(curl -s -X POST "http://127.0.0.1:8011/predict" \
+            -H 'Content-Type: application/json' \
+            -H "x-api-key: ${API_KEY}" \
+            -d '{"features":[5.1,3.5,1.4,0.2], "return_proba":true}')
+          echo "$RESP" | jq .
+          echo "$RESP" | jq -e 'has("prediction") and has("proba") and has("latency_ms")' >/dev/null
+
+      - name: Shutdown
+        if: always()
+        run: |
+          [ -f /tmp/uvicorn.pid ] && kill $(cat /tmp/uvicorn.pid) || true
+          sleep 1
+          pkill -f "uvicorn" || true
+
+      - name: Upload logs (on failure)
+        if: failure()
+        uses: actions/upload-artifact@v4
+        with:
+          name: uvicorn-logs
+          path: /tmp/uvicorn.log
diff --git a/.github/workflows/ci-pr.yml b/.github/workflows/ci-pr.yml
new file mode 100644
index 0000000..83458ff
--- /dev/null
+++ b/.github/workflows/ci-pr.yml
@@ -0,0 +1,76 @@
+name: PR CI (fast)
+
+on:
+  pull_request:
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - uses: actions/setup-python@v5
+        with:
+          python-version: '3.11'
+          cache: 'pip'
+          cache-dependency-path: |
+            requirements.txt
+            requirements-dev.txt
+
+      - name: Install deps
+        run: |
+          python -m pip install --upgrade pip
+          pip install -r requirements.txt -r requirements-dev.txt
+
+      - name: Unit tests
+        env:
+          PYTHONDONTWRITEBYTECODE: 1
+          PYTHONPATH: ${{ github.workspace }}
+          API_KEY: test-key
+        run: |
+          python -m pytest --cov=serving_app --cov-report=term-missing
+
+  smoke:
+    runs-on: ubuntu-latest
+    needs: test
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-python@v5
+        with:
+          python-version: '3.11'
+
+      - name: Install runtime deps only
+        run: |
+          python -m pip install --upgrade pip
+          pip install -r requirements.txt
+
+      - name: Boot API (no training for speed)
+        env:
+          API_KEY: test-key
+        run: |
+          set -euo pipefail
+          uvicorn serving_app.main:app --host 127.0.0.1 --port 8011 >/tmp/uvicorn.log 2>&1 &
+          echo $! > /tmp/uvicorn.pid
+          for i in {1..40}; do
+            if curl -sf http://127.0.0.1:8011/health >/dev/null; then
+              echo "API is up"
+              exit 0
+            fi
+            sleep 0.5
+          done
+          echo "API failed to start"; cat /tmp/uvicorn.log || true; exit 1
+
+      - name: Shutdown
+        if: always()
+        run: |
+          [ -f /tmp/uvicorn.pid ] && kill "$(cat /tmp/uvicorn.pid)" || true
+          sleep 1
+          pkill -f "uvicorn" || true
+
+      - name: Upload logs (on failure)
+        if: failure()
+        uses: actions/upload-artifact@v4
+        with:
+          name: uvicorn-logs
+          path: /tmp/uvicorn.log
+
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
deleted file mode 100644
index 17ac317..0000000
--- a/.github/workflows/ci.yml
+++ /dev/null
@@ -1,32 +0,0 @@
-name: CI
-on: [push, pull_request]
-jobs:
-  smoke:
-    runs-on: ubuntu-latest
-    steps:
-      - uses: actions/checkout@v4
-      - uses: actions/setup-python@v5
-        with:
-          python-version: '3.11'
-          cache: 'pip'
-          cache-dependency-path: 'requirements.txt'
-      - run: pip install -r requirements.txt
-      - name: Train model
-        run: python -m training.train
-      - name: Boot API
-        env: { API_KEY: "" }
-        run: |
-          uvicorn serving_app.main:app --host 127.0.0.1 --port 8011 &
-          echo $! > uvicorn.pid
-          for i in {1..40}; do
-            curl -sf http://127.0.0.1:8011/health && break
-            sleep 0.5
-          done
-      - name: Predict smoke
-        run: |
-          curl -s -X POST http://127.0.0.1:8011/predict \
-            -H 'Content-Type: application/json' \
-            -d '{"features":[5.1,3.5,1.4,0.2], "return_proba":true}' | python -m json.tool
-      - name: Shutdown
-        if: always()
-        run: kill $(cat uvicorn.pid) || true
diff --git a/.gitignore b/.gitignore
index 4f7011c..cb66d3d 100644
--- a/.gitignore
+++ b/.gitignore
@@ -19,3 +19,4 @@ venv/
 # Models/artifacts (adjust to your project)
 models/
 artifacts/
+.coverage
diff --git a/README.md b/README.md
index dd26753..3bacd89 100644
--- a/README.md
+++ b/README.md
@@ -1,8 +1,12 @@
-# Serving App (FastAPI + scikit-learn)
+# Serving App  
+🚀 A production-style ML API built with **FastAPI** + **scikit-learn**
+
+[![CI](https://github.com/KyleSDeveloper/serving_app/actions/workflows/ci-pr.yml/badge.svg)](https://github.com/KyleSDeveloper/serving_app/actions/workflows/ci-pr.yml)
 ![Python 3.11](https://img.shields.io/badge/Python-3.11-blue)
 ![FastAPI](https://img.shields.io/badge/FastAPI-ready-teal)
 ![Docker](https://img.shields.io/badge/Docker-ready-informational)
 
+
 A tiny, production-style ML serving skeleton.  
 Trains a scikit-learn classifier (Iris demo) and serves predictions via FastAPI.
 
diff --git a/requirements-dev.txt b/requirements-dev.txt
new file mode 100644
index 0000000..785a62e
--- /dev/null
+++ b/requirements-dev.txt
@@ -0,0 +1,6 @@
+pytest
+pytest-cov
+requests
+ruff
+mypy
+httpx
diff --git a/tests/conftest.py b/tests/conftest.py
new file mode 100644
index 0000000..363ae40
--- /dev/null
+++ b/tests/conftest.py
@@ -0,0 +1,74 @@
+# tests/conftest.py
+import os
+import inspect
+import contextlib
+import numpy as np
+import pytest
+from fastapi.testclient import TestClient
+from serving_app import main as m  # where app/_model/_n_features live
+
+
+def _noop():
+    """No-op dependency override."""
+    return None
+
+
+class _DummyModel:
+    def predict(self, X):
+        X = np.asarray(X)
+        # return numpy array so .astype works
+        return np.zeros(len(X), dtype=int)
+
+    def predict_proba(self, X):
+        X = np.asarray(X)
+        # shape (n_samples, 2)
+        return np.tile([0.4, 0.6], (len(X), 1))
+
+
+@pytest.fixture(scope="session")
+def client():
+    # --- Save originals so we can restore later ---
+    orig_overrides = dict(getattr(m.app, "dependency_overrides", {}))
+    orig_model = getattr(m, "_model", None)
+    orig_n_features = getattr(m, "_n_features", None)
+
+    # 1) Env for any key checks
+    os.environ.setdefault("API_KEY", "test-key")
+    os.environ.setdefault("X_API_KEY", "test-key")
+
+    # 2) Disable ALL route dependencies (auth/key checks etc.)
+    for route in m.app.routes:
+        if getattr(route, "dependencies", None):
+            for dep in route.dependencies:
+                if callable(getattr(dep, "dependency", None)):
+                    m.app.dependency_overrides[dep.dependency] = _noop
+
+    # Also best-effort override any module callables that look like auth/key checks
+    for name, obj in inspect.getmembers(m):
+        if callable(obj) and any(t in name.lower() for t in ("key", "auth", "token", "apikey")):
+            m.app.dependency_overrides[obj] = _noop
+
+    # 3) Start app, then stub the model so startup can’t overwrite it
+    with TestClient(m.app) as c:
+        c.headers.update({
+            "x-api-key": "test-key",
+            "X-API-Key": "test-key",
+            "Authorization": "Bearer test-key",
+            "api-key": "test-key",
+        })
+        m._model = _DummyModel()
+        m._n_features = 4
+        yield c
+
+    # --- Restore originals ---
+    with contextlib.suppress(Exception):
+        m.app.dependency_overrides.clear()
+        m.app.dependency_overrides.update(orig_overrides)
+        m._model = orig_model
+        m._n_features = orig_n_features
+
+
+
+
+
+
diff --git a/tests/test_health.py b/tests/test_health.py
new file mode 100644
index 0000000..8007e78
--- /dev/null
+++ b/tests/test_health.py
@@ -0,0 +1,9 @@
+def test_health(client):
+    r = client.get("/health")
+    assert r.status_code == 200
+    body = r.json()
+    assert body.get("ok") is True
+    assert isinstance(body.get("model_loaded"), bool)
+    assert isinstance(body.get("version"), str) and body["version"]
+
+
diff --git a/tests/test_metrics.py b/tests/test_metrics.py
new file mode 100644
index 0000000..e69de29
diff --git a/tests/test_predict.py b/tests/test_predict.py
new file mode 100644
index 0000000..66605d0
--- /dev/null
+++ b/tests/test_predict.py
@@ -0,0 +1,37 @@
+import pytest
+
+def test_predict_happy_path(client):
+    # requires 4 features
+    payload = {"features": [0.1, 0.2, 0.3, 0.4]}
+    r = client.post("/predict", json=payload)
+    assert r.status_code == 200
+    out = r.json()
+    # Accept the app's actual schema
+    assert isinstance(out, dict)
+    assert "prediction" in out
+    assert "proba" in out  # may be None if return_proba=False
+    assert "latency_ms" in out
+
+def test_predict_with_proba(client):
+    payload = {"features": [0.9, -0.1, 0.3, 0.0], "return_proba": True}
+    r = client.post("/predict", json=payload)
+    assert r.status_code == 200
+    out = r.json()
+    assert "prediction" in out
+    assert "proba" in out and out["proba"] is not None
+    # if your proba is a list of class probs, sanity-check shape/type:
+    assert isinstance(out["proba"], (list, tuple))
+
+
+@pytest.mark.parametrize("bad", [
+    {},  # missing features
+    {"features": None},
+    {"features": "not-a-list"},
+    {"features": []},  # empty not allowed (if you allow empty, drop this)
+    {"features": [None, 1, 2]},
+    {"features": ["a", "b"]},
+])
+def test_predict_bad_payloads(client, bad):
+    r = client.post("/predict", json=bad)
+    assert r.status_code in (400, 422)
+
diff --git a/tests/test_predict_batch.py b/tests/test_predict_batch.py
new file mode 100644
index 0000000..d58ba69
--- /dev/null
+++ b/tests/test_predict_batch.py
@@ -0,0 +1,32 @@
+import pytest
+
+def test_predict_batch_happy_path(client):
+    payload = {"items": [[0.0, 1.0, 0.0, 1.0],
+                         [1.0, 0.0, 1.0, 0.0]]}
+    r = client.post("/predict_batch", json=payload)
+    assert r.status_code == 200
+    data = r.json()
+    if isinstance(data, dict) and "predictions" in data:
+        assert isinstance(data["predictions"], list) and len(data["predictions"]) == 2
+    else:
+        assert isinstance(data, list) and len(data) == 2
+
+def test_predict_batch_with_proba(client):
+    payload = {"items": [[0.2, 0.3, 0.4, 0.5],
+                         [0.8, 0.1, 0.2, 0.3]], "return_proba": True}
+    r = client.post("/predict_batch", json=payload)
+    assert r.status_code == 200
+    out = r.json()
+    assert isinstance(out, (dict, list))
+
+@pytest.mark.parametrize("bad", [
+    {},                          # missing items
+    {"items": None},
+    {"items": "nope"},
+    {"items": [[0.0, 1.0], ["a", "b"]]},  # mixed types
+])
+def test_predict_batch_bad_payloads(client, bad):
+    r = client.post("/predict_batch", json=bad)
+    assert r.status_code in (400, 422)
+
+
diff --git a/tests/test_version.py b/tests/test_version.py
new file mode 100644
index 0000000..1850c6f
--- /dev/null
+++ b/tests/test_version.py
@@ -0,0 +1,5 @@
+def test_version(client):
+    r = client.get("/version")
+    assert r.status_code == 200
+    data = r.json()
+    assert "version" in data and isinstance(data["version"], str)