diff --git a/.github/workflows/release-please.yml b/.github/workflows/release-please.yml
new file mode 100644
index 00000000..7ad80591
--- /dev/null
+++ b/.github/workflows/release-please.yml
@@ -0,0 +1,24 @@
+name: release-please
+
+# Cuts versioned contract-checkpoint releases (tag + GitHub release + CHANGELOG)
+# from conventional commits. These are contract snapshots, NOT a deploy gate.
+
+on:
+  push:
+    branches:
+      - main
+  workflow_dispatch:
+
+permissions:
+  contents: write
+  pull-requests: write
+
+jobs:
+  release-please:
+    if: github.repository == 'scaleapi/scale-agentex'
+    runs-on: ubuntu-latest
+    steps:
+      - uses: googleapis/release-please-action@5c625bfb5d1ff62eadeeb3772007f7f66fdcf071 # v4.4.1
+        with:
+          config-file: release-please-config.json
+          manifest-file: .release-please-manifest.json
diff --git a/.release-please-manifest.json b/.release-please-manifest.json
new file mode 100644
index 00000000..466df71c
--- /dev/null
+++ b/.release-please-manifest.json
@@ -0,0 +1,3 @@
+{
+  ".": "0.1.0"
+}
diff --git a/agentex/src/_version.py b/agentex/src/_version.py
new file mode 100644
index 00000000..bd85479f
--- /dev/null
+++ b/agentex/src/_version.py
@@ -0,0 +1,3 @@
+"""Single source of the agentex contract version (bumped by release-please)."""
+
+__version__ = "0.1.0"  # x-release-please-version
diff --git a/agentex/src/api/app.py b/agentex/src/api/app.py
index 41a9eada..ab0f4a32 100644
--- a/agentex/src/api/app.py
+++ b/agentex/src/api/app.py
@@ -21,6 +21,7 @@
 from fastapi.responses import JSONResponse
 from fastapi.staticfiles import StaticFiles
 
+from src._version import __version__
 from src.adapters.crud_store.exceptions import ItemDoesNotExist
 from src.adapters.http.adapter_httpx import HttpxGateway
 from src.api.authentication_middleware import AgentexAuthMiddleware
@@ -42,6 +43,7 @@
     task_retention,
     tasks,
 )
+from src.api.version_header_middleware import VersionHeaderMiddleware
 from src.config import dependencies
 from src.config.dependencies import (
     GlobalDependencies,
@@ -108,6 +110,7 @@ async def lifespan(_: FastAPI):
 
 fastapi_app = FastAPI(
     title="Agentex API",
+    version=__version__,
     openapi_url="/openapi.json",
     docs_url="/swagger",
     redoc_url="/api",
@@ -137,6 +140,7 @@ async def lifespan(_: FastAPI):
 # Add Authentication middleware
 fastapi_app.add_middleware(AgentexAuthMiddleware)
 fastapi_app.add_middleware(RequestLoggingMiddleware)
+fastapi_app.add_middleware(VersionHeaderMiddleware)
 
 # Mount the MkDocs site
 docs_path = Path(__file__).parent.parent.parent / "docs" / "site"
diff --git a/agentex/src/api/version_header_middleware.py b/agentex/src/api/version_header_middleware.py
new file mode 100644
index 00000000..23b76559
--- /dev/null
+++ b/agentex/src/api/version_header_middleware.py
@@ -0,0 +1,30 @@
+"""ASGI middleware that advertises the server's contract version on responses."""
+
+from __future__ import annotations
+
+from starlette.datastructures import MutableHeaders
+from starlette.types import ASGIApp, Message, Receive, Scope, Send
+
+from src._version import __version__
+
+VERSION_HEADER = "x-agentex-version"
+
+
+class VersionHeaderMiddleware:
+    """Set `X-Agentex-Version` on every HTTP response so clients can detect a
+    server whose contract version is incompatible with their build."""
+
+    def __init__(self, app: ASGIApp) -> None:
+        self.app = app
+
+    async def __call__(self, scope: Scope, receive: Receive, send: Send) -> None:
+        if scope["type"] != "http":
+            await self.app(scope, receive, send)
+            return
+
+        async def send_with_version(message: Message) -> None:
+            if message["type"] == "http.response.start":
+                MutableHeaders(scope=message)[VERSION_HEADER] = __version__
+            await send(message)
+
+        await self.app(scope, receive, send_with_version)
diff --git a/agentex/tests/unit/api/test_version_header_middleware.py b/agentex/tests/unit/api/test_version_header_middleware.py
new file mode 100644
index 00000000..807f9301
--- /dev/null
+++ b/agentex/tests/unit/api/test_version_header_middleware.py
@@ -0,0 +1,22 @@
+"""Unit tests for VersionHeaderMiddleware — sets X-Agentex-Version on responses."""
+
+import pytest
+from src._version import __version__
+from src.api.version_header_middleware import VERSION_HEADER, VersionHeaderMiddleware
+from starlette.applications import Starlette
+from starlette.responses import PlainTextResponse
+from starlette.routing import Route
+from starlette.testclient import TestClient
+
+
+@pytest.mark.unit
+def test_sets_version_header_on_responses():
+    def endpoint(request):
+        return PlainTextResponse("ok")
+
+    wrapped = VersionHeaderMiddleware(Starlette(routes=[Route("/x", endpoint)]))
+    client = TestClient(wrapped)
+
+    response = client.get("/x")
+    assert response.status_code == 200
+    assert response.headers[VERSION_HEADER] == __version__
diff --git a/release-please-config.json b/release-please-config.json
new file mode 100644
index 00000000..45985166
--- /dev/null
+++ b/release-please-config.json
@@ -0,0 +1,32 @@
+{
+  "$schema": "https://raw.githubusercontent.com/googleapis/release-please/main/schemas/config.json",
+  "include-v-in-tag": true,
+  "include-component-in-tag": false,
+  "bump-minor-pre-major": true,
+  "bump-patch-for-minor-pre-major": false,
+  "bootstrap-sha": "ab469df91bba043ea25356c89147d29f7df03bad",
+  "changelog-sections": [
+    { "type": "feat", "section": "Features" },
+    { "type": "fix", "section": "Bug Fixes" },
+    { "type": "perf", "section": "Performance Improvements" },
+    { "type": "revert", "section": "Reverts" },
+    { "type": "docs", "section": "Documentation" },
+    { "type": "refactor", "section": "Refactors" },
+    { "type": "chore", "section": "Chores", "hidden": true },
+    { "type": "test", "section": "Tests", "hidden": true },
+    { "type": "ci", "section": "Continuous Integration", "hidden": true },
+    { "type": "build", "section": "Build System", "hidden": true },
+    { "type": "style", "section": "Styles", "hidden": true }
+  ],
+  "packages": {
+    ".": {
+      "release-type": "python",
+      "package-name": "agentex",
+      "extra-files": [
+        "agentex/src/_version.py",
+        { "type": "yaml", "path": "agentex/openapi.yaml", "jsonpath": "$.info.version" },
+        { "type": "toml", "path": "agentex/pyproject.toml", "jsonpath": "$.project.version" }
+      ]
+    }
+  }
+}