diff --git a/package.json b/package.json
index 1dd9a3745..ccdc2dd09 100644
--- a/package.json
+++ b/package.json
@@ -16,8 +16,8 @@
     "apps/*"
   ],
   "engines": {
-    "node": ">=20.6.0",
-    "npm": ">=8.0.0"
+    "node": ">=22.0.0",
+    "npm": ">=10.0.0"
   },
   "devDependencies": {
     "@modelcontextprotocol/sdk": "^1.30.0",
diff --git a/tests/unit/test_node_engines_floor.py b/tests/unit/test_node_engines_floor.py
new file mode 100644
index 000000000..ac6658fe5
--- /dev/null
+++ b/tests/unit/test_node_engines_floor.py
@@ -0,0 +1,223 @@
+"""Regression tests for the declared Node engine floor.
+
+The root `package.json` advertises the Node versions this repo supports. That
+claim is load-bearing in a place that never fails loudly: Vercel reads
+`engines.node` to pick the runtime for `apps/web`. `npm install` only *warns*
+(`EBADENGINE`) when a package wants a newer Node, so a stale floor never turns a
+check red.
+
+Before this test the floor said `>=20.6.0` while every gate in the repo ran on
+Node 22 (`ci.yml`, `e2e-tests.yml`, `security.yml`, and `apps/web/Dockerfile`),
+and core runtime dependencies — `openai@7`, `ai@7`, the Supabase client — all
+declare `>=22`. Node 20 was therefore advertised but never built or tested.
+
+The invariant locked in here is *toolchain consistency*: the version the repo
+promises must be the version it actually builds and tests on.
+
+Deliberately not asserted is "the floor dominates every dependency's declared
+floor". Much of the tree uses *union* ranges — `vitest@4.1.10` is
+`^20.0.0 || ^22.0.0 || >=24.0.0`, `eslint-visitor-keys@5.0.1` is
+`^20.19.0 || ^22.13.0 || >=24` — whose trailing `>=` branch is one alternative
+among several, not an unconditional minimum. Both explicitly admit Node 22.
+Reading such a range as "requires >=24" is simply wrong, so `_parse_floor`
+below refuses to guess: it accepts only a range that is a single, complete
+`>=` clause and returns `None` for every other form. A selected runtime
+dependency that adopts an unsupported form fails loudly rather than silently
+contributing a fabricated floor.
+"""
+
+from __future__ import annotations
+
+import json
+import re
+from collections.abc import Iterator
+from pathlib import Path
+from typing import Any
+
+import pytest
+import yaml
+
+REPO_ROOT = Path(__file__).resolve().parents[2]
+PACKAGE_JSON = REPO_ROOT / "package.json"
+PACKAGE_LOCK = REPO_ROOT / "package-lock.json"
+WEB_DOCKERFILE = REPO_ROOT / "apps/web/Dockerfile"
+
+# Workflows whose Node pin defines "the version we actually test on".
+CI_WORKFLOWS = (
+    REPO_ROOT / ".github/workflows/ci.yml",
+    REPO_ROOT / ".github/workflows/e2e-tests.yml",
+    REPO_ROOT / ".github/workflows/security.yml",
+)
+
+# Direct runtime dependencies whose floor the deployed app must satisfy.
+RUNTIME_DEPS_UNDER_TEST = ("openai", "ai", "@ai-sdk/gateway")
+
+# Anchored: the whole range must be one `>=` clause. An unanchored search would
+# happily pull `>=24.0.0` out of `^20.0.0 || ^22.0.0 || >=24.0.0` and report a
+# floor of 24 for a range that accepts Node 20.
+_MIN_VERSION = re.compile(r"^>=\s*v?(\d+)(?:\.(\d+))?(?:\.(\d+))?$")
+_DOCKER_NODE = re.compile(r"^FROM\s+node:(\d+)", re.MULTILINE)
+
+
+def _walk(node: Any) -> Iterator[Any]:
+    """Yield every mapping nested anywhere inside a parsed YAML document."""
+    if isinstance(node, dict):
+        yield node
+        for value in node.values():
+            yield from _walk(value)
+    elif isinstance(node, list):
+        for item in node:
+            yield from _walk(item)
+
+
+def _pinned_node_majors(workflow: Path) -> set[int]:
+    """Every Node major a workflow pins via `actions/setup-node`.
+
+    Parsed rather than text-matched so a commented-out or documentation-only
+    `node-version:` line cannot fail this test spuriously.
+    """
+    document = yaml.safe_load(workflow.read_text())
+    majors: set[int] = set()
+    for mapping in _walk(document):
+        pin = (mapping.get("with") or {}).get("node-version") if mapping else None
+        if pin is None:
+            continue
+        match = re.match(r"v?(\d+)", str(pin).strip())
+        if match:
+            majors.add(int(match.group(1)))
+    return majors
+
+
+def _parse_floor(spec: str | None) -> tuple[int, int, int] | None:
+    """Return the floor of a semver range, or `None` if it is not a bare `>=`.
+
+    Only a range that is *entirely* one `>=X[.Y[.Z]]` clause has an unambiguous
+    minimum. Unions (`a || b`) and compound ranges (`>=22 <24`) return `None`
+    rather than a guess — see the module docstring.
+    """
+    if not spec:
+        return None
+    match = _MIN_VERSION.match(spec.strip())
+    if match is None:
+        return None
+    major, minor, patch = match.groups()
+    return (int(major), int(minor or 0), int(patch or 0))
+
+
+def _load(path: Path) -> dict:
+    assert path.exists(), f"{path} should exist"
+    return json.loads(path.read_text())
+
+
+def _declared_floor() -> tuple[int, int, int]:
+    engines = _load(PACKAGE_JSON).get("engines") or {}
+    floor = _parse_floor(engines.get("node"))
+    assert (
+        floor is not None
+    ), "root package.json must declare engines.node as a >= range"
+    return floor
+
+
+def _locked_floor(name: str) -> tuple[int, int, int] | None:
+    """Strictest declared Node floor for any copy of `name` in the lockfile."""
+    strictest: tuple[int, int, int] | None = None
+    for path, meta in (_load(PACKAGE_LOCK).get("packages") or {}).items():
+        if not path or not isinstance(meta, dict):
+            continue
+        if path.split("node_modules/")[-1] != name:
+            continue
+        floor = _parse_floor((meta.get("engines") or {}).get("node"))
+        if floor is not None and (strictest is None or floor > strictest):
+            strictest = floor
+    return strictest
+
+
+def test_declared_floor_matches_the_version_ci_tests_on() -> None:
+    """The advertised major must be the major every CI workflow pins."""
+    declared_major = _declared_floor()[0]
+    for workflow in CI_WORKFLOWS:
+        assert workflow.exists(), f"{workflow} should exist"
+        pinned = _pinned_node_majors(workflow)
+        assert pinned, f"{workflow.name} should pin a node-version"
+        assert pinned == {declared_major}, (
+            f"{workflow.name} tests on Node {sorted(pinned)} but package.json "
+            f"advertises >={declared_major}. The repo must promise what it tests."
+        )
+
+
+def test_declared_floor_matches_the_version_the_image_ships() -> None:
+    """The advertised major must be the major the production image is built on."""
+    assert WEB_DOCKERFILE.exists(), f"{WEB_DOCKERFILE} should exist"
+    tags = {int(m) for m in _DOCKER_NODE.findall(WEB_DOCKERFILE.read_text())}
+    assert tags, "apps/web/Dockerfile should build FROM a pinned node: tag"
+    declared_major = _declared_floor()[0]
+    assert tags == {declared_major}, (
+        f"apps/web/Dockerfile ships Node {sorted(tags)} but package.json "
+        f"advertises >={declared_major}."
+    )
+
+
+@pytest.mark.parametrize("dependency", RUNTIME_DEPS_UNDER_TEST)
+def test_declared_floor_satisfies_core_runtime_dependencies(dependency: str) -> None:
+    """A runtime dep must never demand a newer Node than Vercel is told to use."""
+    required = _locked_floor(dependency)
+    assert required is not None, (
+        f"expected {dependency} to declare engines.node in package-lock.json as "
+        "a bare '>=' range. Either it is now absent, or it moved to a union or "
+        "compound range that _parse_floor deliberately refuses to reduce to a "
+        "single floor. Re-read the range by hand and either widen the parser or "
+        "drop this dependency from RUNTIME_DEPS_UNDER_TEST — do not let the "
+        "check pass vacuously."
+    )
+    declared = _declared_floor()
+    assert declared >= required, (
+        f"{dependency} requires Node >={'.'.join(map(str, required))} but "
+        f"package.json advertises >={'.'.join(map(str, declared))}, so Vercel "
+        "may select a runtime the dependency does not support"
+    )
+
+
+@pytest.mark.parametrize(
+    ("spec", "expected"),
+    [
+        (">=22.0.0", (22, 0, 0)),
+        (">=22", (22, 0, 0)),
+        (">= 20.6.0", (20, 6, 0)),
+        ("  >=22.0.0  ", (22, 0, 0)),
+        ("v22.0.0", None),
+        ("^20.0.0", None),
+        ("", None),
+        (None, None),
+        # Union ranges have no single minimum: the trailing `>=` branch is one
+        # alternative, not a floor. These are the real ranges carried by
+        # vitest@4.1.10, eslint-visitor-keys@5.0.1, chrome-devtools-mcp@1.6.0
+        # and vite@8.2.0 — every one of them admits Node 22, so reading the
+        # last branch as a requirement would be actively wrong.
+        ("^20.0.0 || ^22.0.0 || >=24.0.0", None),
+        ("^20.19.0 || ^22.13.0 || >=24", None),
+        ("^20.19.0 || >=22.12.0", None),
+        (">=22.0.0 || >=24.0.0", None),
+        # Compound ranges are bounded above, so `>=` alone does not describe them.
+        (">=22.0.0 <24.0.0", None),
+    ],
+)
+def test_parse_floor(spec: str | None, expected: tuple[int, int, int] | None) -> None:
+    assert _parse_floor(spec) == expected
+
+
+def test_pinned_node_majors_ignores_commented_and_unrelated_keys(
+    tmp_path: Path,
+) -> None:
+    """A `node-version` outside a `with:` block must not be read as a pin."""
+    workflow = tmp_path / "sample.yml"
+    workflow.write_text(
+        "jobs:\n"
+        "  build:\n"
+        "    steps:\n"
+        "      - uses: actions/setup-node@v4\n"
+        '        with:\n          node-version: "22"\n'
+        "      # node-version: 18   <- a comment must be ignored\n"
+        "      - name: not a setup step\n"
+        "        env:\n          NOTE: node-version 16 mentioned in prose\n"
+    )
+    assert _pinned_node_majors(workflow) == {22}