diff --git a/SVSim.Bootstrap/Importers/AchievementCatalogImporter.cs b/SVSim.Bootstrap/Importers/AchievementCatalogImporter.cs
new file mode 100644
index 0000000..1558a85
--- /dev/null
+++ b/SVSim.Bootstrap/Importers/AchievementCatalogImporter.cs
@@ -0,0 +1,60 @@
+using Microsoft.EntityFrameworkCore;
+using SVSim.Bootstrap.Models.Seed;
+using SVSim.Database;
+using SVSim.Database.Models;
+
+namespace SVSim.Bootstrap.Importers;
+
+/// <summary>
+/// Idempotent upsert of achievement-catalog rows from <c>seeds/achievement-catalog.json</c>.
+/// Keyed by (AchievementType, Level) so re-running with new captures grows the ladder.
+/// Rows missing from the seed are LEFT INTACT.
+/// </summary>
+public class AchievementCatalogImporter
+{
+    public async Task<int> ImportAsync(SVSimDbContext context, string seedDir)
+    {
+        var seed = SeedLoader.LoadList<AchievementCatalogSeed>(Path.Combine(seedDir, "achievement-catalog.json"));
+        if (seed.Count == 0)
+        {
+            Console.WriteLine("[AchievementCatalogImporter] No seed rows; skipping.");
+            return 0;
+        }
+
+        var existing = await context.AchievementCatalog
+            .ToDictionaryAsync(e => (e.AchievementType, e.Level));
+        int created = 0, updated = 0;
+        var unmappedTypes = new HashSet<int>();
+        foreach (var s in seed)
+        {
+            if (s.AchievementType == 0 || s.Level == 0) continue;
+            var key = (s.AchievementType, s.Level);
+            var entry = existing.TryGetValue(key, out var ex) ? ex : new AchievementCatalogEntry
+            {
+                AchievementType = s.AchievementType,
+                Level = s.Level,
+            };
+            entry.Name = s.Name;
+            entry.RequireNumber = s.RequireNumber;
+            entry.RewardType = s.RewardType;
+            entry.RewardDetailId = s.RewardDetailId;
+            entry.RewardNumber = s.RewardNumber;
+            entry.OrderNum = s.OrderNum;
+            entry.EventType = s.EventType;
+            entry.EventArg = s.EventArg;
+            if (ex is null) { context.AchievementCatalog.Add(entry); existing[key] = entry; created++; }
+            else updated++;
+            if (s.EventType is null) unmappedTypes.Add(s.AchievementType);
+        }
+
+        await context.SaveChangesAsync();
+        Console.WriteLine($"[AchievementCatalogImporter] +{created}/~{updated}");
+        if (unmappedTypes.Count > 0)
+        {
+            Console.WriteLine($"[AchievementCatalogImporter] WARN: {unmappedTypes.Count} types " +
+                              $"with no event_type: [{string.Join(", ", unmappedTypes.OrderBy(x => x))}] — " +
+                              "add to ACHIEVEMENT_EVENT_MAP in data_dumps/extract/extract-achievements.py");
+        }
+        return created + updated;
+    }
+}
diff --git a/SVSim.Bootstrap/Models/Seed/AchievementCatalogSeed.cs b/SVSim.Bootstrap/Models/Seed/AchievementCatalogSeed.cs
new file mode 100644
index 0000000..4d07870
--- /dev/null
+++ b/SVSim.Bootstrap/Models/Seed/AchievementCatalogSeed.cs
@@ -0,0 +1,17 @@
+using System.Text.Json.Serialization;
+
+namespace SVSim.Bootstrap.Models.Seed;
+
+public sealed class AchievementCatalogSeed
+{
+    [JsonPropertyName("achievement_type")] public int AchievementType { get; set; }
+    [JsonPropertyName("level")] public int Level { get; set; }
+    [JsonPropertyName("name")] public string Name { get; set; } = "";
+    [JsonPropertyName("require_number")] public int RequireNumber { get; set; }
+    [JsonPropertyName("reward_type")] public int RewardType { get; set; }
+    [JsonPropertyName("reward_detail_id")] public long RewardDetailId { get; set; }
+    [JsonPropertyName("reward_number")] public int RewardNumber { get; set; }
+    [JsonPropertyName("order_num")] public int OrderNum { get; set; }
+    [JsonPropertyName("event_type")] public string? EventType { get; set; }
+    [JsonPropertyName("event_arg")] public int? EventArg { get; set; }
+}
diff --git a/SVSim.UnitTests/Importers/AchievementCatalogImporterTests.cs b/SVSim.UnitTests/Importers/AchievementCatalogImporterTests.cs
new file mode 100644
index 0000000..2768b17
--- /dev/null
+++ b/SVSim.UnitTests/Importers/AchievementCatalogImporterTests.cs
@@ -0,0 +1,88 @@
+using Microsoft.EntityFrameworkCore;
+using Microsoft.Extensions.DependencyInjection;
+using SVSim.Bootstrap.Importers;
+using SVSim.Database;
+using SVSim.UnitTests.Infrastructure;
+
+namespace SVSim.UnitTests.Importers;
+
+public class AchievementCatalogImporterTests
+{
+    private static string SeedDir => Path.Combine(AppContext.BaseDirectory, "Data", "seeds");
+
+    [Test]
+    public async Task Imports_captured_achievement_tiers_from_seed()
+    {
+        using var factory = new SVSimTestFactory();
+        using var scope = factory.Services.CreateScope();
+        var db = scope.ServiceProvider.GetRequiredService<SVSimDbContext>();
+
+        await new AchievementCatalogImporter().ImportAsync(db, SeedDir);
+
+        var swordLevel = await db.AchievementCatalog
+            .Where(r => r.AchievementType == 12)
+            .OrderBy(r => r.Level).LastOrDefaultAsync();
+        Assert.That(swordLevel, Is.Not.Null);
+        Assert.That(swordLevel!.EventType, Is.EqualTo("class_level_up:swordcraft"));
+    }
+
+    [Test]
+    public async Task Imports_multiple_levels_for_same_type()
+    {
+        using var factory = new SVSimTestFactory();
+        using var scope = factory.Services.CreateScope();
+        var db = scope.ServiceProvider.GetRequiredService<SVSimDbContext>();
+
+        await new AchievementCatalogImporter().ImportAsync(db, SeedDir);
+
+        // Hand-add a tier not present in the seed (use a high level the seed won't contain).
+        db.AchievementCatalog.Add(new SVSim.Database.Models.AchievementCatalogEntry
+        {
+            AchievementType = 12, Level = 99,
+            Name = "Reach level 999 in Swordcraft (synthetic)", RequireNumber = 999,
+            RewardType = 5, RewardDetailId = 100211062, RewardNumber = 3, OrderNum = 10,
+            EventType = "class_level_up:swordcraft", EventArg = null,
+        });
+        await db.SaveChangesAsync();
+
+        await new AchievementCatalogImporter().ImportAsync(db, SeedDir);
+
+        int swordTiers = await db.AchievementCatalog.CountAsync(r => r.AchievementType == 12);
+        Assert.That(swordTiers, Is.GreaterThanOrEqualTo(3),
+            "hand-added tier 99 must coexist with seeded tiers 6 and 7");
+    }
+
+    [Test]
+    public async Task Is_idempotent_on_rerun()
+    {
+        using var factory = new SVSimTestFactory();
+        using var scope = factory.Services.CreateScope();
+        var db = scope.ServiceProvider.GetRequiredService<SVSimDbContext>();
+
+        await new AchievementCatalogImporter().ImportAsync(db, SeedDir);
+        int before = await db.AchievementCatalog.CountAsync();
+        await new AchievementCatalogImporter().ImportAsync(db, SeedDir);
+        int after = await db.AchievementCatalog.CountAsync();
+
+        Assert.That(after, Is.EqualTo(before));
+    }
+
+    [Test]
+    public async Task Empty_seed_is_no_op()
+    {
+        using var factory = new SVSimTestFactory();
+        using var scope = factory.Services.CreateScope();
+        var db = scope.ServiceProvider.GetRequiredService<SVSimDbContext>();
+
+        string tmp = Path.Combine(Path.GetTempPath(), $"seed-{Guid.NewGuid()}");
+        Directory.CreateDirectory(tmp);
+        try
+        {
+            File.WriteAllText(Path.Combine(tmp, "achievement-catalog.json"), "[]");
+            await new AchievementCatalogImporter().ImportAsync(db, tmp);
+            int count = await db.AchievementCatalog.CountAsync();
+            Assert.That(count, Is.EqualTo(0));
+        }
+        finally { Directory.Delete(tmp, true); }
+    }
+}