diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 1a01f71..3d0148b 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -47,8 +47,11 @@ jobs:
       - name: Install dependencies
         run: uv sync --group dev
 
-      - name: Run tests
-        run: uv run pytest -v
+      - name: Run tests with coverage
+        # Ratchet: raise --cov-fail-under as coverage improves. Target is 80%;
+        # the floor starts at the currently achievable 20% so the gate blocks
+        # regressions today instead of failing on day one.
+        run: uv run pytest -v --cov --cov-report=term --cov-report=xml --cov-fail-under=20
 
   workspace-alignment:
     runs-on: ubuntu-latest
diff --git a/pyproject.toml b/pyproject.toml
index ce27432..a0162fa 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -13,6 +13,7 @@ dependencies = [
 dev = [
     "pre-commit>=4.3.0",
     "pytest>=9.0.1",
+    "pytest-cov>=6.0",
     "ruff>=0.16,<0.17",
 ]
 
@@ -24,6 +25,11 @@ exclude = ["repositories"]
 [tool.pytest.ini_options]
 testpaths = ["tests"]
 
+[tool.coverage.run]
+# Measure the workspace's own code only. Without this, a bare `--cov` also
+# counts tests/ as covered code and reports a misleadingly high number.
+source = [".ai-workspace"]
+
 [tool.ruff.lint]
 select = ["E", "F", "I", "UP", "B", "SIM"]
 ignore = ["E501"]