diff --git a/pyproject.toml b/pyproject.toml
index 70f124104..b70f36914 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -10,6 +10,7 @@ dependencies = []
 [project.optional-dependencies]
 dev = [
     "pytest>=8.0",
+    "pytest-timeout>=2.3",
     "pyright>=1.1.409",
 ]
 
@@ -22,6 +23,15 @@ packages = ["src/aelfrice"]
 
 [tool.pytest.ini_options]
 testpaths = ["tests"]
+# Test policy: every test must deterministically terminate. 5s default
+# wall-clock timeout for unit/property tests. Subprocess-driven CLI/MCP
+# integration tests (v0.6.0+) override per-test via @pytest.mark.timeout(N).
+timeout = 5
+strict_markers = true
+markers = [
+    "regression: cumulative integration scenarios run alongside the unit suite",
+    "uat: v1.0 acceptance-criteria tests, run as the final pre-tag gate",
+]
 
 [tool.pyright]
 include = ["src/aelfrice", "tests"]
diff --git a/uv.lock b/uv.lock
index a48889b88..6e70085d4 100644
--- a/uv.lock
+++ b/uv.lock
@@ -11,12 +11,14 @@ source = { editable = "." }
 dev = [
     { name = "pyright" },
     { name = "pytest" },
+    { name = "pytest-timeout" },
 ]
 
 [package.metadata]
 requires-dist = [
     { name = "pyright", marker = "extra == 'dev'", specifier = ">=1.1.409" },
     { name = "pytest", marker = "extra == 'dev'", specifier = ">=8.0" },
+    { name = "pytest-timeout", marker = "extra == 'dev'", specifier = ">=2.3" },
 ]
 provides-extras = ["dev"]
 
@@ -103,6 +105,18 @@ wheels = [
     { url = "https://files.pythonhosted.org/packages/d4/24/a372aaf5c9b7208e7112038812994107bc65a84cd00e0354a88c2c77a617/pytest-9.0.3-py3-none-any.whl", hash = "sha256:2c5efc453d45394fdd706ade797c0a81091eccd1d6e4bccfcd476e2b8e0ab5d9", size = 375249, upload-time = "2026-04-07T17:16:16.13Z" },
 ]
 
+[[package]]
+name = "pytest-timeout"
+version = "2.4.0"
+source = { registry = "https://pypi.org/simple" }
+dependencies = [
+    { name = "pytest" },
+]
+sdist = { url = "https://files.pythonhosted.org/packages/ac/82/4c9ecabab13363e72d880f2fb504c5f750433b2b6f16e99f4ec21ada284c/pytest_timeout-2.4.0.tar.gz", hash = "sha256:7e68e90b01f9eff71332b25001f85c75495fc4e3a836701876183c4bcfd0540a", size = 17973, upload-time = "2025-05-05T19:44:34.99Z" }
+wheels = [
+    { url = "https://files.pythonhosted.org/packages/fa/b6/3127540ecdf1464a00e5a01ee60a1b09175f6913f0644ac748494d9c4b21/pytest_timeout-2.4.0-py3-none-any.whl", hash = "sha256:c42667e5cdadb151aeb5b26d114aff6bdf5a907f176a007a30b940d3d865b5c2", size = 14382, upload-time = "2025-05-05T19:44:33.502Z" },
+]
+
 [[package]]
 name = "typing-extensions"
 version = "4.15.0"