diff --git a/docs/build-manual.py b/docs/build-manual.py
index 64cb612..959f0b4 100644
--- a/docs/build-manual.py
+++ b/docs/build-manual.py
@@ -279,7 +279,14 @@ def build_site(root: Path, out: Path) -> list[dict]:
             continue
 
         # Section 5: category index page keeps its slot; entries explode.
-        slug_dir = "functions"
+        #
+        # Deliberately NOT "functions": Cloudflare Pages reserves a top-level
+        # `functions/` directory in the deploy output for Pages Functions
+        # (server-side handlers) and silently drops it from the static-asset
+        # upload. The pages build fine and never arrive — every entry 404s in
+        # production while working locally. test_site_avoids_reserved_dir
+        # guards this.
+        slug_dir = "reference"
         if rel.name == "index.md":
             target = out / slug_dir / "index.md"
             target.parent.mkdir(parents=True, exist_ok=True)
diff --git a/docs/verify-manual.py b/docs/verify-manual.py
index 4ba56af..f904d4d 100644
--- a/docs/verify-manual.py
+++ b/docs/verify-manual.py
@@ -203,7 +203,7 @@ def test_site_build_produces_function_pages():
         sidebar = build_manual.build_site(docs / "manual", out)
         pages = list(out.rglob("*.md*"))
         assert (out / "index.md").exists(), "landing page missing"
-        fn_pages = [p for p in pages if "functions" in p.parts and p.name != "index.mdx"]
+        fn_pages = [p for p in pages if "reference" in p.parts and p.name != "index.mdx"]
         assert len(fn_pages) > 80, f"expected >80 function pages, got {len(fn_pages)}"
         assert not (out / "00-name.md").exists(), "site:false page was published"
         assert sidebar, "sidebar structure is empty"
@@ -293,6 +293,29 @@ def test_sidebar_has_no_duplicate_functions_entry():
     assert len(labels) == 15, f"expected Overview + 14 categories, got {len(labels)}"
 
 
+def test_site_avoids_reserved_dir():
+    """No output directory may collide with a Cloudflare Pages reserved name.
+
+    Pages treats a top-level `functions/` directory in the deploy output as
+    Pages Functions (server-side handlers) and drops it from the static-asset
+    upload. The build succeeds, wrangler reports success, and every page under
+    it 404s in production while working perfectly under `astro preview` — so
+    only a check on the emitted tree catches it.
+    """
+    import build_manual
+
+    reserved = {"functions", "_worker.js", "_routes.json"}
+    docs = Path(__file__).parent
+    with tempfile.TemporaryDirectory() as d:
+        out = Path(d)
+        build_manual.build_site(docs / "manual", out)
+        clashes = {p.name for p in out.iterdir()} & reserved
+    assert not clashes, (
+        f"site output has Cloudflare Pages reserved name(s): {sorted(clashes)} "
+        "— these are silently excluded from the deployed assets"
+    )
+
+
 TESTS = [v for k, v in sorted(globals().items()) if k.startswith("test_")]