feat: port the site ports and picker checks

Tables with a download link stack on phones, the browser check covers
the lookup, a hash typed in the search, breadcrumbs, previous and next
across tabs, glossary terms and the 404 hint. validate_site budgets the
Pagefind index pieces and takes the base path without mkdocs.yml. A
test holds the picker to install.narrow() on 180 selections.

tests/test_site_picker.py

@@ -0,0 +1,91 @@
+"""The file picker on Get your files lists what the installer installs.
+
+The picker reads a compacted copy of each install/<platform>.json and keeps
+a file when one of its systems is chosen, or when it has none and "other"
+is chosen, then prints `--system` with the choices. install.py --system
+narrows with install.narrow(). The two must agree file for file, or the
+list the page shows is not what the command it prints installs.
+"""
+
+from __future__ import annotations
+
+import importlib.util
+import json
+import random
+import re
+import sys
+import tempfile
+import unittest
+from pathlib import Path
+
+REPO_ROOT = Path(__file__).resolve().parents[1]
+sys.path.insert(0, str(REPO_ROOT / "scripts"))
+
+_spec = importlib.util.spec_from_file_location("install", REPO_ROOT / "install.py")
+install = importlib.util.module_from_spec(_spec)
+_spec.loader.exec_module(install)
+
+PICKER = REPO_ROOT / "website" / "src" / "components" / "FilePicker.astro"
+
+
+def picked(data: dict, chosen: set[str]) -> list[str]:
+    """The picker's rule, as FilePicker.astro applies it."""
+    wanted = {index for index, system in enumerate(data["systems"]) if system["id"] in chosen}
+    other = install.OTHER_SYSTEMS in chosen
+    return [dest for dest, _size, systems in data["files"]
+            if (any(s in wanted for s in systems) if systems else other)]
+
+
+class PickerMatchesInstaller(unittest.TestCase):
+    def setUp(self):
+        import sitestarlight  # noqa: PLC0415
+
+        self.folder = tempfile.TemporaryDirectory(dir=REPO_ROOT / "tmp" if (REPO_ROOT / "tmp").is_dir() else None)
+        self.out = Path(self.folder.name)
+        self.count = sitestarlight.picker_data(REPO_ROOT / "install", self.out)
+
+    def tearDown(self):
+        self.folder.cleanup()
+
+    def test_every_manifest_has_its_list(self):
+        index = json.loads((self.out / "index.json").read_text(encoding="utf-8"))
+        manifests = [p for p in (REPO_ROOT / "install").glob("*.json")
+                     if "files" in json.loads(p.read_text(encoding="utf-8"))]
+        self.assertEqual(len(index), len(manifests))
+        self.assertEqual(self.count, len(manifests))
+
+    def test_random_selections_equal_install_narrow(self):
+        rng = random.Random(20261022)
+        checked = 0
+        for entry in json.loads((self.out / "index.json").read_text(encoding="utf-8")):
+            platform = entry["platform"]
+            manifest = json.loads((REPO_ROOT / "install" / f"{platform}.json").read_text(encoding="utf-8"))
+            data = json.loads((self.out / f"{platform}.json").read_text(encoding="utf-8"))
+            choices = [s["id"] for s in data["systems"]] + ([install.OTHER_SYSTEMS] if data["other"] else [])
+            for _round in range(10):
+                chosen = set(rng.sample(choices, rng.randint(1, min(len(choices), 6))))
+                files, _omitted = install.narrow(manifest["files"], [], sorted(chosen), [], [])
+                with self.subTest(platform=platform, systems=sorted(chosen)):
+                    self.assertEqual(sorted(picked(data, chosen)), sorted(f["dest"] for f in files))
+                checked += 1
+        self.assertGreater(checked, 0)
+
+    def test_choices_are_what_the_installer_offers(self):
+        for entry in json.loads((self.out / "index.json").read_text(encoding="utf-8")):
+            manifest = json.loads((REPO_ROOT / "install" / f"{entry['platform']}.json").read_text(encoding="utf-8"))
+            data = json.loads((self.out / f"{entry['platform']}.json").read_text(encoding="utf-8"))
+            offered = install.available_choices(manifest["files"], [])["systems"]
+            ours = [s["id"] for s in data["systems"]] + ([install.OTHER_SYSTEMS] if data["other"] else [])
+            with self.subTest(platform=entry["platform"]):
+                self.assertEqual(ours, offered)
+
+    def test_component_applies_the_same_rule(self):
+        """The rule above is the component's: a change to one fails here."""
+        source = PICKER.read_text(encoding="utf-8")
+        self.assertIn("systems.length ? systems.some((s) => wanted.has(s)) : other", source)
+        self.assertIn("picked.includes('other')", source)
+        self.assertRegex(source, re.escape("--system ${picked.join(',')}"))
+
+
+if __name__ == "__main__":
+    unittest.main()