Randomize questions on every Anki regen

Also make explanation section slightly more readable

test_amateurfunk_anki.py

@@ -11,6 +11,7 @@ import tempfile
 import unittest
 import zipfile
 from pathlib import Path
+from unittest.mock import patch
 
 import amateurfunk_anki as aa
 
@@ -108,6 +109,24 @@ def extract_collection(apkg_path: Path, tmp: Path):
     return tmp / "collection.anki2", media, names
 
 
+class TestResolveShuffleSeed(unittest.TestCase):
+    """Unit coverage for the shuffle-seed resolution itself.
+
+    The CLI-level test patches `resolve_shuffle_seed` out, so the
+    actual default-seed behavior is only exercised here.
+    """
+
+    def test_explicit_seed_is_passed_through(self):
+        self.assertEqual(aa.resolve_shuffle_seed("my-seed"), "my-seed")
+
+    def test_omitted_seed_mints_a_fresh_value_each_call(self):
+        first = aa.resolve_shuffle_seed(None)
+        second = aa.resolve_shuffle_seed(None)
+        self.assertIsInstance(first, str)
+        self.assertTrue(first)
+        self.assertNotEqual(first, second)
+
+
 class TestAnkiBuild(unittest.TestCase):
     def setUp(self):
         self.tmp = tempfile.TemporaryDirectory()
@@ -479,6 +498,7 @@ class TestAnkiBuild(unittest.TestCase):
         common = [
             "--data", str(self.data_dir),
             "--explanations", str(self.explanations_path),
+            "--seed", "stable-test-seed",
             "--epoch", "1234567890",
         ]
         aa.main([*common, "--out", str(out_a)])
@@ -488,6 +508,32 @@ class TestAnkiBuild(unittest.TestCase):
             second = out_b / first.name
             self.assertEqual(first.read_bytes(), second.read_bytes(), first.name)
 
+    def test_cli_without_seed_reshuffles_each_build(self):
+        out_a = self.root / "anki-fresh-a"
+        out_b = self.root / "anki-fresh-b"
+        common = [
+            "--data", str(self.data_dir),
+            "--explanations", str(self.explanations_path),
+            "--epoch", "1234567890",
+        ]
+
+        with patch(
+            "amateurfunk_anki.resolve_shuffle_seed",
+            side_effect=["fresh-a", "fresh-b"],
+        ) as resolve_seed:
+            aa.main([*common, "--out", str(out_a)])
+            aa.main([*common, "--out", str(out_b)])
+
+        resolved_inputs = [
+            call.args[0] for call in resolve_seed.call_args_list
+        ]
+        self.assertEqual(resolved_inputs, [None, None])
+        byte_equal = [
+            first.read_bytes() == (out_b / first.name).read_bytes()
+            for first in sorted(out_a.glob("*.apkg"))
+        ]
+        self.assertFalse(all(byte_equal))
+
 
 class TestRealExplanationsFile(unittest.TestCase):
     """Validate the repo's actual explanations.json against the live catalog.