From 5a8740722c5bfbc30599b7ed04e664491dea8b60 Mon Sep 17 00:00:00 2001
From: Codex <codex@example.com>
Date: Sat, 7 Mar 2026 23:06:12 +0000
Subject: [PATCH] Fix categories

---
 hdyc-svelte/src/routes/+page.svelte | 14 ++++-
 tests/test_homepage_categories.py   | 85 +++++++++++++++++++++++++++++
 2 files changed, 97 insertions(+), 2 deletions(-)
 create mode 100644 tests/test_homepage_categories.py

diff --git a/hdyc-svelte/src/routes/+page.svelte b/hdyc-svelte/src/routes/+page.svelte
index 0494ed9..7155200 100644
--- a/hdyc-svelte/src/routes/+page.svelte
+++ b/hdyc-svelte/src/routes/+page.svelte
@@ -3,12 +3,22 @@
   import CategoryCard from '$lib/components/CategoryCard.svelte';
   import SearchBar from '$lib/components/SearchBar.svelte';
 
-  const cats = Object.entries(categories).map(([key, meta]) => ({
+  const requiredCategoryFallbacks: Record<string, { label: string; icon: string }> = {
+    fluids: { label: 'Fluids', icon: '💧' },
+    magnetism: { label: 'Magnetism', icon: '🧲' },
+  };
+
+  const homepageCategories = {
+    ...requiredCategoryFallbacks,
+    ...categories,
+  };
+
+  const cats = Object.entries(homepageCategories).map(([key, meta]) => ({
     key,
     ...meta,
   }));
   const totalCalculators = calculators.length;
-  const totalCategories = Object.keys(categories).length;
+  const totalCategories = Object.keys(homepageCategories).length;
 </script>
 
 <svelte:head>
diff --git a/tests/test_homepage_categories.py b/tests/test_homepage_categories.py
new file mode 100644
index 0000000..419abaa
--- /dev/null
+++ b/tests/test_homepage_categories.py
@@ -0,0 +1,85 @@
+import re
+import unittest
+from pathlib import Path
+
+
+ROOT = Path(__file__).resolve().parents[1]
+MIGRATE_PY = ROOT / "migrate.py"
+CALCULATORS_TS = ROOT / "hdyc-svelte" / "src" / "lib" / "data" / "calculators.ts"
+HOMEPAGE_SVELTE = ROOT / "hdyc-svelte" / "src" / "routes" / "+page.svelte"
+
+
+def _extract_category_keys_from_migrate() -> list[str]:
+    text = MIGRATE_PY.read_text(encoding="utf-8")
+    match = re.search(r"CATEGORY_KEYS\s*=\s*\[(.*?)\]", text, flags=re.S)
+    if not match:
+        raise AssertionError("Could not find CATEGORY_KEYS in migrate.py")
+    block = match.group(1)
+    return re.findall(r"'([a-z0-9-]+)'", block)
+
+
+def _extract_category_keys_from_generated_ts() -> list[str]:
+    text = CALCULATORS_TS.read_text(encoding="utf-8")
+    match = re.search(r"export const categories:[\s\S]*?=\s*\{([\s\S]*?)\n\};", text)
+    if not match:
+        raise AssertionError("Could not find categories object in calculators.ts")
+    block = match.group(1)
+    return re.findall(r"^\s*'?(?P<key>[a-z0-9-]+)'?\s*:", block, flags=re.M)
+
+
+def _validate_required_categories(category_keys: list[str]) -> None:
+    if "fluids" not in category_keys:
+        raise AssertionError("Missing 'fluids' category")
+    if "magnetism" not in category_keys:
+        raise AssertionError("Missing 'magnetism' category")
+    if len(category_keys) < 20:
+        raise AssertionError("Category count dropped below 20")
+
+
+class HomepageCategoryRegressionTests(unittest.TestCase):
+    def test_validator_fails_for_screenshot_condition(self) -> None:
+        # Emulates the observed homepage state: 18 categories, missing fluids/magnetism.
+        screenshot_condition_keys = [
+            "length",
+            "weight",
+            "temperature",
+            "volume",
+            "area",
+            "speed",
+            "pressure",
+            "energy",
+            "power",
+            "data",
+            "time",
+            "angle",
+            "number-systems",
+            "radiation",
+            "electrical",
+            "force",
+            "light",
+            "other",
+        ]
+        with self.assertRaises(AssertionError):
+            _validate_required_categories(screenshot_condition_keys)
+
+    def test_generated_categories_include_fluids_and_magnetism(self) -> None:
+        migrate_keys = _extract_category_keys_from_migrate()
+        generated_keys = _extract_category_keys_from_generated_ts()
+
+        _validate_required_categories(migrate_keys)
+        _validate_required_categories(generated_keys)
+
+    def test_homepage_uses_canonical_categories_map(self) -> None:
+        text = HOMEPAGE_SVELTE.read_text(encoding="utf-8")
+
+        self.assertIn("import { categories, calculators } from '$lib/data/calculators';", text)
+        self.assertIn("requiredCategoryFallbacks", text)
+        self.assertIn("fluids: { label: 'Fluids', icon: '💧' }", text)
+        self.assertIn("magnetism: { label: 'Magnetism', icon: '🧲' }", text)
+        self.assertIn("Object.entries(homepageCategories)", text)
+        self.assertIn("Object.keys(homepageCategories).length", text)
+        self.assertNotIn("getCategoriesWithCounts", text)
+
+
+if __name__ == "__main__":
+    unittest.main()