diff --git a/JobTrackerApi.Tests/HumanLanguageCatalogTests.cs b/JobTrackerApi.Tests/HumanLanguageCatalogTests.cs
new file mode 100644
index 0000000..34e204d
--- /dev/null
+++ b/JobTrackerApi.Tests/HumanLanguageCatalogTests.cs
@@ -0,0 +1,57 @@
+using JobTrackerApi.Models;
+using Xunit;
+
+namespace JobTrackerApi.Tests;
+
+// The catalog used to be built solely from CultureInfo.GetCultures, so which languages it
+// recognised depended on the host's ICU data: 806 cultures on a normal machine, exactly 1
+// under globalization-invariant mode. CV imports silently lost their Languages section on a
+// container with trimmed or absent ICU data, and every existing test still passed locally.
+//
+// These pin the explicitly seeded catalog, so deleting the seed list fails here rather than
+// in production on a machine nobody tested.
+public sealed class HumanLanguageCatalogTests
+{
+    [Theory]
+    [InlineData("English")]
+    [InlineData("Norwegian")]
+    [InlineData("French")]
+    [InlineData("Spanish")]
+    [InlineData("German")]
+    [InlineData("Arabic")]
+    [InlineData("Chinese")]
+    [InlineData("Polish")]
+    public void Common_languages_resolve_without_relying_on_host_culture_data(string language)
+    {
+        Assert.Equal(language, HumanLanguageCatalog.NormalizeLanguageName(language));
+    }
+
+    [Theory]
+    [InlineData("norsk")]
+    [InlineData("bokmål")]
+    [InlineData("nynorsk")]
+    public void Norwegian_aliases_resolve_to_the_canonical_name(string alias)
+    {
+        Assert.Equal("Norwegian", HumanLanguageCatalog.NormalizeLanguageName(alias));
+    }
+
+    [Theory]
+    [InlineData("C#")]
+    [InlineData("Leadership")]
+    [InlineData("Public speaking")]
+    [InlineData("Go")]      // a programming language, not a human one
+    [InlineData("Java")]    // Javanese is a language; Java is not
+    [InlineData("Swift")]
+    [InlineData("Rust")]
+    public void Technical_skills_are_not_treated_as_human_languages(string skill)
+    {
+        Assert.Null(HumanLanguageCatalog.NormalizeLanguageName(skill));
+    }
+
+    [Fact]
+    public void A_language_embedded_in_a_phrase_is_extracted_with_its_level()
+    {
+        Assert.Equal("Norwegian", HumanLanguageCatalog.NormalizeLanguageName("Native Norwegian speaker"));
+        Assert.Equal("Native", HumanLanguageCatalog.ExtractLevel("Native Norwegian speaker"));
+    }
+}
diff --git a/Models/HumanLanguageCatalog.cs b/Models/HumanLanguageCatalog.cs
index 6951aaa..8ed2b33 100644
--- a/Models/HumanLanguageCatalog.cs
+++ b/Models/HumanLanguageCatalog.cs
@@ -103,6 +103,40 @@ public static class HumanLanguageCatalog
             map.TryAdd(normalizedAlias, normalizedCanonical);
         }
 
+        // Seeded FIRST, and deliberately not derived from the host.
+        //
+        // This table used to come only from CultureInfo.GetCultures, which returns whatever
+        // culture data the machine happens to carry: 806 entries on a normal Linux or Windows
+        // box, exactly 1 under globalization-invariant mode, and an English-only subset on a
+        // container with trimmed ICU data. So whether "Norwegian" was recognised as a human
+        // language depended on the deployment environment, not on the CV. Under invariant mode
+        // every language was silently dropped and a CV import lost its Languages section with
+        // no error at all.
+        //
+        // These are the languages a CV realistically lists. Culture enumeration still runs
+        // below and still adds breadth for free, but nothing here depends on it.
+        //
+        // Nothing in this list may collide with a technical skill — "Go", "Java", "Swift",
+        // "Rust" and "Basic" are deliberately absent. "Basic" is also a proficiency level.
+        string[] seed =
+        [
+            "English", "Norwegian", "Swedish", "Danish", "Finnish", "Icelandic",
+            "German", "Dutch", "French", "Spanish", "Portuguese", "Italian",
+            "Polish", "Czech", "Slovak", "Slovenian", "Croatian", "Serbian", "Bosnian",
+            "Bulgarian", "Romanian", "Hungarian", "Greek", "Albanian", "Macedonian",
+            "Russian", "Ukrainian", "Belarusian", "Lithuanian", "Latvian", "Estonian",
+            "Turkish", "Arabic", "Hebrew", "Persian", "Kurdish", "Pashto", "Urdu",
+            "Hindi", "Bengali", "Punjabi", "Gujarati", "Marathi", "Tamil", "Telugu",
+            "Malayalam", "Kannada", "Sinhala", "Nepali",
+            "Chinese", "Japanese", "Korean", "Vietnamese", "Thai", "Lao", "Khmer",
+            "Burmese", "Malay", "Indonesian", "Filipino", "Tagalog", "Javanese",
+            "Swahili", "Amharic", "Somali", "Hausa", "Yoruba", "Igbo", "Zulu", "Afrikaans",
+            "Catalan", "Basque", "Galician", "Welsh", "Irish", "Scottish Gaelic", "Maltese",
+            "Latin", "Esperanto", "Armenian", "Georgian", "Azerbaijani", "Kazakh", "Uzbek",
+        ];
+
+        foreach (var language in seed) Add(language, language);
+
         foreach (var culture in CultureInfo.GetCultures(CultureTypes.NeutralCultures | CultureTypes.SpecificCultures))
         {
             var english = CleanCultureLanguageName(culture.EnglishName);