diff --git a/bruno/neon-sprawl-server/ability-catalog/Health after ability catalog load.bru b/bruno/neon-sprawl-server/ability-catalog/Health after ability catalog load.bru
new file mode 100644
index 0000000..757385e
--- /dev/null
+++ b/bruno/neon-sprawl-server/ability-catalog/Health after ability catalog load.bru	
@@ -0,0 +1,25 @@
+meta {
+  name: GET health (ability catalog boot NEO-77)
+  type: http
+  seq: 1
+}
+
+get {
+  url: {{baseUrl}}/health
+  body: none
+  auth: none
+}
+
+docs {
+  NEO-77 loads content/abilities/*_abilities.json at startup (fail-fast). No ability HTTP API in this story — use this request to confirm the host started after catalog validation.
+}
+
+tests {
+  test("status 200", function () {
+    expect(res.getStatus()).to.equal(200);
+  });
+
+  test("service identity", function () {
+    expect(res.getBody().service).to.equal("NeonSprawl.Server");
+  });
+}
diff --git a/server/NeonSprawl.Server.Tests/Game/Combat/AbilityCatalogTestPaths.cs b/server/NeonSprawl.Server.Tests/Game/Combat/AbilityCatalogTestPaths.cs
new file mode 100644
index 0000000..1965b73
--- /dev/null
+++ b/server/NeonSprawl.Server.Tests/Game/Combat/AbilityCatalogTestPaths.cs
@@ -0,0 +1,17 @@
+using NeonSprawl.Server.Game.Combat;
+
+namespace NeonSprawl.Server.Tests.Game.Combat;
+
+internal static class AbilityCatalogTestPaths
+{
+    internal static string DiscoverRepoAbilitiesDirectory() =>
+        AbilityCatalogPathResolution.TryDiscoverAbilitiesDirectory(AppContext.BaseDirectory)
+        ?? throw new InvalidOperationException(
+            "Could not discover repo content/abilities from AppContext.BaseDirectory; run tests from the neon-sprawl clone.");
+
+    internal static string DiscoverRepoAbilityDefSchemaPath() =>
+        AbilityCatalogPathResolution.ResolveAbilityDefSchemaPath(
+            DiscoverRepoAbilitiesDirectory(),
+            configuredSchemaPath: null,
+            contentRootPath: string.Empty);
+}
diff --git a/server/NeonSprawl.Server.Tests/Game/Combat/AbilityDefinitionCatalogLoaderTests.cs b/server/NeonSprawl.Server.Tests/Game/Combat/AbilityDefinitionCatalogLoaderTests.cs
new file mode 100644
index 0000000..30a7623
--- /dev/null
+++ b/server/NeonSprawl.Server.Tests/Game/Combat/AbilityDefinitionCatalogLoaderTests.cs
@@ -0,0 +1,333 @@
+using System.Net;
+using System.Text;
+using System.Text.Json.Nodes;
+using Microsoft.AspNetCore.Mvc.Testing;
+using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.Logging.Abstractions;
+using NeonSprawl.Server.Game.Combat;
+using NeonSprawl.Server.Tests;
+using Xunit;
+
+namespace NeonSprawl.Server.Tests.Game.Combat;
+
+public class AbilityDefinitionCatalogLoaderTests
+{
+    private const string ValidPrototypeCatalogJson =
+        """
+        {
+          "schemaVersion": 1,
+          "abilities": [
+            {
+              "id": "prototype_pulse",
+              "displayName": "Prototype Pulse",
+              "baseDamage": 25,
+              "cooldownSeconds": 3.0,
+              "abilityKind": "attack"
+            },
+            {
+              "id": "prototype_guard",
+              "displayName": "Prototype Guard",
+              "baseDamage": 0,
+              "cooldownSeconds": 6.0,
+              "abilityKind": "utility"
+            },
+            {
+              "id": "prototype_dash",
+              "displayName": "Prototype Dash",
+              "baseDamage": 0,
+              "cooldownSeconds": 4.0,
+              "abilityKind": "movement"
+            },
+            {
+              "id": "prototype_burst",
+              "displayName": "Prototype Burst",
+              "baseDamage": 40,
+              "cooldownSeconds": 5.0,
+              "abilityKind": "attack"
+            }
+          ]
+        }
+        """;
+
+    private static (string Root, string AbilitiesDir, string SchemaPath) CreateTempContentLayout()
+    {
+        var root = Directory.CreateTempSubdirectory("neon-sprawl-abilitycat-");
+        var abilitiesDir = Path.Combine(root.FullName, "content", "abilities");
+        var schemaDir = Path.Combine(root.FullName, "content", "schemas");
+        Directory.CreateDirectory(abilitiesDir);
+        Directory.CreateDirectory(schemaDir);
+        var schemaPath = Path.Combine(schemaDir, "ability-def.schema.json");
+        File.Copy(AbilityCatalogTestPaths.DiscoverRepoAbilityDefSchemaPath(), schemaPath, overwrite: true);
+        return (root.FullName, abilitiesDir, schemaPath);
+    }
+
+    private static void WriteCatalog(string abilitiesDir, string catalogJson) =>
+        File.WriteAllText(Path.Combine(abilitiesDir, "prototype_abilities.json"), catalogJson, Encoding.UTF8);
+
+    private static JsonObject GetAbilityRow(JsonObject catalogRoot, string abilityId)
+    {
+        var abilities = catalogRoot["abilities"] as JsonArray
+                        ?? throw new InvalidOperationException("expected abilities array");
+        foreach (var node in abilities)
+        {
+            if (node is JsonObject row && row["id"]?.GetValue<string>() == abilityId)
+                return row;
+        }
+
+        throw new InvalidOperationException($"ability id not found: {abilityId}");
+    }
+
+    private static AbilityDefinitionCatalog LoadCatalog(string abilitiesDir, string schemaPath) =>
+        AbilityDefinitionCatalogLoader.Load(abilitiesDir, schemaPath, NullLogger.Instance);
+
+    [Fact]
+    public void Load_ShouldSucceed_WhenCatalogMatchesPrototypeContract()
+    {
+        // Arrange
+        var (_, abilitiesDir, schemaPath) = CreateTempContentLayout();
+        WriteCatalog(abilitiesDir, ValidPrototypeCatalogJson);
+        // Act
+        var catalog = LoadCatalog(abilitiesDir, schemaPath);
+        // Assert
+        Assert.Equal(4, catalog.DistinctAbilityCount);
+        Assert.Equal(1, catalog.CatalogJsonFileCount);
+        Assert.True(catalog.TryGetAbility("prototype_pulse", out var pulse));
+        Assert.NotNull(pulse);
+        Assert.Equal(25, pulse!.BaseDamage);
+        Assert.Equal(3.0, pulse.CooldownSeconds);
+        Assert.Equal("attack", pulse.AbilityKind);
+    }
+
+    [Fact]
+    public void Load_ShouldThrow_WhenAbilitiesIsNotArray()
+    {
+        // Arrange
+        var (_, abilitiesDir, schemaPath) = CreateTempContentLayout();
+        File.WriteAllText(
+            Path.Combine(abilitiesDir, "bad_abilities.json"),
+            """{"schemaVersion": 1, "abilities": "nope"}""",
+            Encoding.UTF8);
+        // Act
+        var ex = Record.Exception(() => LoadCatalog(abilitiesDir, schemaPath));
+        // Assert
+        var ioe = Assert.IsType<InvalidOperationException>(ex);
+        Assert.Contains("bad_abilities.json", ioe.Message, StringComparison.Ordinal);
+        Assert.Contains("expected top-level 'abilities' array", ioe.Message, StringComparison.Ordinal);
+    }
+
+    [Fact]
+    public void Load_ShouldThrow_WhenSchemaVersionIsNotOne()
+    {
+        // Arrange
+        var (_, abilitiesDir, schemaPath) = CreateTempContentLayout();
+        File.WriteAllText(
+            Path.Combine(abilitiesDir, "bad_abilities.json"),
+            """{"schemaVersion": 2, "abilities": []}""",
+            Encoding.UTF8);
+        // Act
+        var ex = Record.Exception(() => LoadCatalog(abilitiesDir, schemaPath));
+        // Assert
+        var ioe = Assert.IsType<InvalidOperationException>(ex);
+        Assert.Contains("expected schemaVersion 1", ioe.Message, StringComparison.Ordinal);
+    }
+
+    [Fact]
+    public void Load_ShouldThrow_WhenDuplicateAbilityIdAcrossFiles()
+    {
+        // Arrange
+        var (_, abilitiesDir, schemaPath) = CreateTempContentLayout();
+        WriteCatalog(abilitiesDir, ValidPrototypeCatalogJson);
+        File.WriteAllText(
+            Path.Combine(abilitiesDir, "extra_abilities.json"),
+            """
+            {
+              "schemaVersion": 1,
+              "abilities": [
+                {
+                  "id": "prototype_pulse",
+                  "displayName": "Duplicate Pulse",
+                  "baseDamage": 1,
+                  "cooldownSeconds": 1.0
+                }
+              ]
+            }
+            """,
+            Encoding.UTF8);
+        // Act
+        var ex = Record.Exception(() => LoadCatalog(abilitiesDir, schemaPath));
+        // Assert
+        var ioe = Assert.IsType<InvalidOperationException>(ex);
+        Assert.Contains("duplicate ability id 'prototype_pulse'", ioe.Message, StringComparison.Ordinal);
+    }
+
+    [Fact]
+    public void Load_ShouldThrow_WhenE5M1GateFails()
+    {
+        // Arrange
+        var (_, abilitiesDir, schemaPath) = CreateTempContentLayout();
+        var root = JsonNode.Parse(ValidPrototypeCatalogJson) as JsonObject
+                   ?? throw new InvalidOperationException("expected object root");
+        var abilities = root["abilities"] as JsonArray
+                        ?? throw new InvalidOperationException("expected abilities array");
+        abilities.RemoveAt(abilities.Count - 1);
+        WriteCatalog(abilitiesDir, root.ToJsonString());
+        // Act
+        var ex = Record.Exception(() => LoadCatalog(abilitiesDir, schemaPath));
+        // Assert
+        var ioe = Assert.IsType<InvalidOperationException>(ex);
+        Assert.Contains("prototype E5M1 expects exactly ability ids", ioe.Message, StringComparison.Ordinal);
+    }
+
+    [Fact]
+    public void Load_ShouldThrow_WhenBaseDamageIsNegative()
+    {
+        // Arrange
+        var (_, abilitiesDir, schemaPath) = CreateTempContentLayout();
+        var root = JsonNode.Parse(ValidPrototypeCatalogJson) as JsonObject
+                   ?? throw new InvalidOperationException("expected object root");
+        GetAbilityRow(root, "prototype_pulse")["baseDamage"] = -1;
+        WriteCatalog(abilitiesDir, root.ToJsonString());
+        // Act
+        var ex = Record.Exception(() => LoadCatalog(abilitiesDir, schemaPath));
+        // Assert
+        var ioe = Assert.IsType<InvalidOperationException>(ex);
+        Assert.Contains("Ability catalog validation failed", ioe.Message, StringComparison.Ordinal);
+        Assert.Contains("baseDamage", ioe.Message, StringComparison.Ordinal);
+    }
+
+    [Fact]
+    public void Load_ShouldThrow_WhenCooldownSecondsIsZero()
+    {
+        // Arrange
+        var (_, abilitiesDir, schemaPath) = CreateTempContentLayout();
+        var root = JsonNode.Parse(ValidPrototypeCatalogJson) as JsonObject
+                   ?? throw new InvalidOperationException("expected object root");
+        GetAbilityRow(root, "prototype_pulse")["cooldownSeconds"] = 0;
+        WriteCatalog(abilitiesDir, root.ToJsonString());
+        // Act
+        var ex = Record.Exception(() => LoadCatalog(abilitiesDir, schemaPath));
+        // Assert
+        var ioe = Assert.IsType<InvalidOperationException>(ex);
+        Assert.Contains("Ability catalog validation failed", ioe.Message, StringComparison.Ordinal);
+        Assert.Contains("cooldownSeconds", ioe.Message, StringComparison.Ordinal);
+    }
+
+    [Fact]
+    public void Load_ShouldThrow_WhenDisplayNameIsEmpty()
+    {
+        // Arrange
+        var (_, abilitiesDir, schemaPath) = CreateTempContentLayout();
+        var root = JsonNode.Parse(ValidPrototypeCatalogJson) as JsonObject
+                   ?? throw new InvalidOperationException("expected object root");
+        GetAbilityRow(root, "prototype_pulse")["displayName"] = "";
+        WriteCatalog(abilitiesDir, root.ToJsonString());
+        // Act
+        var ex = Record.Exception(() => LoadCatalog(abilitiesDir, schemaPath));
+        // Assert
+        var ioe = Assert.IsType<InvalidOperationException>(ex);
+        Assert.Contains("Ability catalog validation failed", ioe.Message, StringComparison.Ordinal);
+        Assert.Contains("displayName", ioe.Message, StringComparison.Ordinal);
+    }
+
+    [Fact]
+    public void Load_ShouldThrow_WhenNoAbilityCatalogFiles()
+    {
+        // Arrange
+        var (_, abilitiesDir, schemaPath) = CreateTempContentLayout();
+        // Act
+        var ex = Record.Exception(() => LoadCatalog(abilitiesDir, schemaPath));
+        // Assert
+        var ioe = Assert.IsType<InvalidOperationException>(ex);
+        Assert.Contains("no *_abilities.json files", ioe.Message, StringComparison.Ordinal);
+    }
+
+    [Fact]
+    public void Load_ShouldThrow_WhenJsonIsInvalid()
+    {
+        // Arrange
+        var (_, abilitiesDir, schemaPath) = CreateTempContentLayout();
+        File.WriteAllText(
+            Path.Combine(abilitiesDir, "bad_abilities.json"),
+            "{not json",
+            Encoding.UTF8);
+        // Act
+        var ex = Record.Exception(() => LoadCatalog(abilitiesDir, schemaPath));
+        // Assert
+        var ioe = Assert.IsType<InvalidOperationException>(ex);
+        Assert.Contains("bad_abilities.json", ioe.Message, StringComparison.Ordinal);
+        Assert.Contains("invalid JSON", ioe.Message, StringComparison.Ordinal);
+    }
+
+    [Fact]
+    public void Load_ShouldThrow_WhenAbilitiesDirectoryMissing()
+    {
+        // Arrange
+        var missingDir = Path.Combine(Path.GetTempPath(), "neon-sprawl-no-abilities-" + Guid.NewGuid().ToString("n"));
+        var schemaPath = AbilityCatalogTestPaths.DiscoverRepoAbilityDefSchemaPath();
+        // Act
+        var ex = Record.Exception(() =>
+            AbilityDefinitionCatalogLoader.Load(missingDir, schemaPath, NullLogger.Instance));
+        // Assert
+        var ioe = Assert.IsType<InvalidOperationException>(ex);
+        Assert.Contains("missing directory", ioe.Message, StringComparison.Ordinal);
+        Assert.Contains(missingDir, ioe.Message, StringComparison.Ordinal);
+    }
+
+    [Fact]
+    public void Load_ShouldThrow_WhenSchemaFileMissing()
+    {
+        // Arrange
+        var (_, abilitiesDir, _) = CreateTempContentLayout();
+        var missingSchema = Path.Combine(abilitiesDir, "missing-ability-def.schema.json");
+        // Act
+        var ex = Record.Exception(() =>
+            AbilityDefinitionCatalogLoader.Load(abilitiesDir, missingSchema, NullLogger.Instance));
+        // Assert
+        var ioe = Assert.IsType<InvalidOperationException>(ex);
+        Assert.Contains("missing schema file", ioe.Message, StringComparison.Ordinal);
+        Assert.Contains(missingSchema, ioe.Message, StringComparison.Ordinal);
+    }
+
+    [Fact]
+    public async Task Host_ShouldResolveCatalogFromDi_WhenStartupSucceeds()
+    {
+        // Arrange
+        await using var factory = new InMemoryWebApplicationFactory();
+        using var client = factory.CreateClient();
+        // Act
+        var response = await client.GetAsync("/health");
+        // Assert
+        Assert.Equal(HttpStatusCode.OK, response.StatusCode);
+        var catalog = factory.Services.GetRequiredService<AbilityDefinitionCatalog>();
+        Assert.Equal(4, catalog.DistinctAbilityCount);
+        Assert.True(catalog.TryGetAbility("prototype_burst", out var burst));
+        Assert.Equal(40, burst!.BaseDamage);
+        Assert.Equal(5.0, burst.CooldownSeconds);
+    }
+
+    [Fact]
+    public void Host_ShouldFailStartup_WhenCatalogDirectoryInvalid()
+    {
+        // Arrange
+        var badDir = Path.Combine(Path.GetTempPath(), "neon-sprawl-empty-abilities-" + Guid.NewGuid().ToString("n"));
+        Directory.CreateDirectory(badDir);
+        try
+        {
+            // Act
+            var ex = Record.Exception(() =>
+            {
+                using var factory = new WebApplicationFactory<Program>().WithWebHostBuilder(b =>
+                    b.UseSetting("Content:AbilitiesDirectory", badDir));
+                factory.CreateClient();
+            });
+            // Assert
+            Assert.NotNull(ex);
+            Assert.Contains("Ability catalog validation failed", ex.ToString(), StringComparison.Ordinal);
+        }
+        finally
+        {
+            if (Directory.Exists(badDir))
+                Directory.Delete(badDir);
+        }
+    }
+}
diff --git a/server/NeonSprawl.Server.Tests/Game/Interaction/SalvageActivityDeniedRegistryWebApplicationFactory.cs b/server/NeonSprawl.Server.Tests/Game/Interaction/SalvageActivityDeniedRegistryWebApplicationFactory.cs
index f9efdbe..c1f96b7 100644
--- a/server/NeonSprawl.Server.Tests/Game/Interaction/SalvageActivityDeniedRegistryWebApplicationFactory.cs
+++ b/server/NeonSprawl.Server.Tests/Game/Interaction/SalvageActivityDeniedRegistryWebApplicationFactory.cs
@@ -6,6 +6,7 @@ using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.Hosting;
 using Microsoft.Extensions.Time.Testing;
 using NeonSprawl.Server.Game.AbilityInput;
+using NeonSprawl.Server.Game.Combat;
 using NeonSprawl.Server.Game.Crafting;
 using NeonSprawl.Server.Game.Gathering;
 using NeonSprawl.Server.Game.Items;
@@ -41,11 +42,15 @@ public sealed class SalvageActivityDeniedRegistryWebApplicationFactory : WebAppl
         var recipesDir = RecipeCatalogPathResolution.TryDiscoverRecipesDirectory(AppContext.BaseDirectory)
             ?? throw new InvalidOperationException(
                 "Could not discover repo content/recipes from AppContext.BaseDirectory; run tests from the neon-sprawl clone.");
+        var abilitiesDir = AbilityCatalogPathResolution.TryDiscoverAbilitiesDirectory(AppContext.BaseDirectory)
+            ?? throw new InvalidOperationException(
+                "Could not discover repo content/abilities from AppContext.BaseDirectory; run tests from the neon-sprawl clone.");
         builder.UseSetting("Content:SkillsDirectory", skillsDir);
         builder.UseSetting("Content:MasteryDirectory", masteryDir);
         builder.UseSetting("Content:ItemsDirectory", itemsDir);
         builder.UseSetting("Content:ResourceNodesDirectory", resourceNodesDir);
         builder.UseSetting("Content:RecipesDirectory", recipesDir);
+        builder.UseSetting("Content:AbilitiesDirectory", abilitiesDir);
         builder.UseSetting("Game:EnableMasteryFixtureApi", "true");
 
         builder.ConfigureTestServices(services =>
diff --git a/server/NeonSprawl.Server.Tests/Game/PositionState/PostgresWebApplicationFactory.cs b/server/NeonSprawl.Server.Tests/Game/PositionState/PostgresWebApplicationFactory.cs
index 0337336..dd6072b 100644
--- a/server/NeonSprawl.Server.Tests/Game/PositionState/PostgresWebApplicationFactory.cs
+++ b/server/NeonSprawl.Server.Tests/Game/PositionState/PostgresWebApplicationFactory.cs
@@ -1,6 +1,7 @@
 using Microsoft.AspNetCore.Hosting;
 using Microsoft.AspNetCore.Mvc.Testing;
 using Microsoft.Extensions.Configuration;
+using NeonSprawl.Server.Game.Combat;
 using NeonSprawl.Server.Game.Crafting;
 using NeonSprawl.Server.Game.Gathering;
 using NeonSprawl.Server.Game.Items;
@@ -39,11 +40,15 @@ public sealed class PostgresWebApplicationFactory : WebApplicationFactory<Progra
         var recipesDir = RecipeCatalogPathResolution.TryDiscoverRecipesDirectory(AppContext.BaseDirectory)
             ?? throw new InvalidOperationException(
                 "Could not discover repo content/recipes from AppContext.BaseDirectory; run tests from the neon-sprawl clone.");
+        var abilitiesDir = AbilityCatalogPathResolution.TryDiscoverAbilitiesDirectory(AppContext.BaseDirectory)
+            ?? throw new InvalidOperationException(
+                "Could not discover repo content/abilities from AppContext.BaseDirectory; run tests from the neon-sprawl clone.");
         builder.UseSetting("Content:SkillsDirectory", skillsDir);
         builder.UseSetting("Content:MasteryDirectory", masteryDir);
         builder.UseSetting("Content:ItemsDirectory", itemsDir);
         builder.UseSetting("Content:ResourceNodesDirectory", resourceNodesDir);
         builder.UseSetting("Content:RecipesDirectory", recipesDir);
+        builder.UseSetting("Content:AbilitiesDirectory", abilitiesDir);
 
         builder.ConfigureAppConfiguration((_, config) =>
         {
diff --git a/server/NeonSprawl.Server.Tests/Game/Skills/MissionRewardDeniedRegistryWebApplicationFactory.cs b/server/NeonSprawl.Server.Tests/Game/Skills/MissionRewardDeniedRegistryWebApplicationFactory.cs
index 1e29349..fb336d1 100644
--- a/server/NeonSprawl.Server.Tests/Game/Skills/MissionRewardDeniedRegistryWebApplicationFactory.cs
+++ b/server/NeonSprawl.Server.Tests/Game/Skills/MissionRewardDeniedRegistryWebApplicationFactory.cs
@@ -6,6 +6,7 @@ using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.Hosting;
 using Microsoft.Extensions.Time.Testing;
 using NeonSprawl.Server.Game.AbilityInput;
+using NeonSprawl.Server.Game.Combat;
 using NeonSprawl.Server.Game.Crafting;
 using NeonSprawl.Server.Game.Mastery;
 using NeonSprawl.Server.Game.PositionState;
@@ -33,9 +34,13 @@ public sealed class MissionRewardDeniedRegistryWebApplicationFactory : WebApplic
         var recipesDir = RecipeCatalogPathResolution.TryDiscoverRecipesDirectory(AppContext.BaseDirectory)
             ?? throw new InvalidOperationException(
                 "Could not discover repo content/recipes from AppContext.BaseDirectory; run tests from the neon-sprawl clone.");
+        var abilitiesDir = AbilityCatalogPathResolution.TryDiscoverAbilitiesDirectory(AppContext.BaseDirectory)
+            ?? throw new InvalidOperationException(
+                "Could not discover repo content/abilities from AppContext.BaseDirectory; run tests from the neon-sprawl clone.");
         builder.UseSetting("Content:SkillsDirectory", skillsDir);
         builder.UseSetting("Content:MasteryDirectory", masteryDir);
         builder.UseSetting("Content:RecipesDirectory", recipesDir);
+        builder.UseSetting("Content:AbilitiesDirectory", abilitiesDir);
 
         builder.ConfigureTestServices(services =>
         {
diff --git a/server/NeonSprawl.Server.Tests/Game/Skills/RefineActivityDeniedRegistryWebApplicationFactory.cs b/server/NeonSprawl.Server.Tests/Game/Skills/RefineActivityDeniedRegistryWebApplicationFactory.cs
index ea04cc8..b0b9a23 100644
--- a/server/NeonSprawl.Server.Tests/Game/Skills/RefineActivityDeniedRegistryWebApplicationFactory.cs
+++ b/server/NeonSprawl.Server.Tests/Game/Skills/RefineActivityDeniedRegistryWebApplicationFactory.cs
@@ -6,6 +6,7 @@ using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.Hosting;
 using Microsoft.Extensions.Time.Testing;
 using NeonSprawl.Server.Game.AbilityInput;
+using NeonSprawl.Server.Game.Combat;
 using NeonSprawl.Server.Game.Crafting;
 using NeonSprawl.Server.Game.Mastery;
 using NeonSprawl.Server.Game.PositionState;
@@ -33,9 +34,13 @@ public sealed class RefineActivityDeniedRegistryWebApplicationFactory : WebAppli
         var recipesDir = RecipeCatalogPathResolution.TryDiscoverRecipesDirectory(AppContext.BaseDirectory)
             ?? throw new InvalidOperationException(
                 "Could not discover repo content/recipes from AppContext.BaseDirectory; run tests from the neon-sprawl clone.");
+        var abilitiesDir = AbilityCatalogPathResolution.TryDiscoverAbilitiesDirectory(AppContext.BaseDirectory)
+            ?? throw new InvalidOperationException(
+                "Could not discover repo content/abilities from AppContext.BaseDirectory; run tests from the neon-sprawl clone.");
         builder.UseSetting("Content:SkillsDirectory", skillsDir);
         builder.UseSetting("Content:MasteryDirectory", masteryDir);
         builder.UseSetting("Content:RecipesDirectory", recipesDir);
+        builder.UseSetting("Content:AbilitiesDirectory", abilitiesDir);
 
         builder.ConfigureTestServices(services =>
         {
diff --git a/server/NeonSprawl.Server.Tests/InMemoryWebApplicationFactory.cs b/server/NeonSprawl.Server.Tests/InMemoryWebApplicationFactory.cs
index 0afbe68..dc283ad 100644
--- a/server/NeonSprawl.Server.Tests/InMemoryWebApplicationFactory.cs
+++ b/server/NeonSprawl.Server.Tests/InMemoryWebApplicationFactory.cs
@@ -5,6 +5,7 @@ using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.Hosting;
 using Microsoft.Extensions.Time.Testing;
 using NeonSprawl.Server.Game.AbilityInput;
+using NeonSprawl.Server.Game.Combat;
 using NeonSprawl.Server.Game.Crafting;
 using NeonSprawl.Server.Game.Gathering;
 using NeonSprawl.Server.Game.Items;
@@ -42,11 +43,15 @@ public sealed class InMemoryWebApplicationFactory : WebApplicationFactory<Progra
         var recipesDir = RecipeCatalogPathResolution.TryDiscoverRecipesDirectory(AppContext.BaseDirectory)
             ?? throw new InvalidOperationException(
                 "Could not discover repo content/recipes from AppContext.BaseDirectory; run tests from the neon-sprawl clone.");
+        var abilitiesDir = AbilityCatalogPathResolution.TryDiscoverAbilitiesDirectory(AppContext.BaseDirectory)
+            ?? throw new InvalidOperationException(
+                "Could not discover repo content/abilities from AppContext.BaseDirectory; run tests from the neon-sprawl clone.");
         builder.UseSetting("Content:SkillsDirectory", skillsDir);
         builder.UseSetting("Content:MasteryDirectory", masteryDir);
         builder.UseSetting("Content:ItemsDirectory", itemsDir);
         builder.UseSetting("Content:ResourceNodesDirectory", resourceNodesDir);
         builder.UseSetting("Content:RecipesDirectory", recipesDir);
+        builder.UseSetting("Content:AbilitiesDirectory", abilitiesDir);
         builder.UseSetting("Game:EnableMasteryFixtureApi", "true");
 
         builder.ConfigureTestServices(services =>
diff --git a/server/NeonSprawl.Server/Game/Combat/AbilityCatalogPathResolution.cs b/server/NeonSprawl.Server/Game/Combat/AbilityCatalogPathResolution.cs
new file mode 100644
index 0000000..cf75380
--- /dev/null
+++ b/server/NeonSprawl.Server/Game/Combat/AbilityCatalogPathResolution.cs
@@ -0,0 +1,60 @@
+namespace NeonSprawl.Server.Game.Combat;
+
+/// <summary>Resolves ability catalog paths for local dev, tests, and container layouts (NEO-77).</summary>
+public static class AbilityCatalogPathResolution
+{
+    /// <summary>Walks <paramref name="startDirectory"/> and parents for an existing <c>content/abilities</c> directory.</summary>
+    public static string? TryDiscoverAbilitiesDirectory(string startDirectory)
+    {
+        for (var dir = new DirectoryInfo(startDirectory); dir is not null; dir = dir.Parent)
+        {
+            var candidate = Path.Combine(dir.FullName, "content", "abilities");
+            if (Directory.Exists(candidate))
+                return Path.GetFullPath(candidate);
+        }
+
+        return null;
+    }
+
+    /// <summary>
+    /// Resolves the abilities catalog directory.
+    /// Empty <paramref name="configuredAbilitiesDirectory"/> triggers discovery from <see cref="AppContext.BaseDirectory"/>.
+    /// </summary>
+    public static string ResolveAbilitiesDirectory(string? configuredAbilitiesDirectory, string contentRootPath)
+    {
+        if (string.IsNullOrWhiteSpace(configuredAbilitiesDirectory))
+        {
+            var discovered = TryDiscoverAbilitiesDirectory(AppContext.BaseDirectory);
+            if (discovered is not null)
+                return discovered;
+
+            throw new InvalidOperationException(
+                "Content:AbilitiesDirectory is not set and auto-discovery failed (no ancestor of AppContext.BaseDirectory contains 'content/abilities'). " +
+                "Set Content:AbilitiesDirectory in configuration or environment (e.g. Content__AbilitiesDirectory).");
+        }
+
+        var trimmed = configuredAbilitiesDirectory.Trim();
+        if (Path.IsPathRooted(trimmed))
+            return Path.GetFullPath(trimmed);
+
+        return Path.GetFullPath(Path.Combine(contentRootPath, trimmed));
+    }
+
+    /// <summary>Resolves JSON Schema path for a single ability row (Draft 2020-12).</summary>
+    public static string ResolveAbilityDefSchemaPath(
+        string abilitiesDirectory,
+        string? configuredSchemaPath,
+        string contentRootPath)
+    {
+        if (!string.IsNullOrWhiteSpace(configuredSchemaPath))
+        {
+            var trimmed = configuredSchemaPath.Trim();
+            if (Path.IsPathRooted(trimmed))
+                return Path.GetFullPath(trimmed);
+
+            return Path.GetFullPath(Path.Combine(contentRootPath, trimmed));
+        }
+
+        return Path.GetFullPath(Path.Combine(abilitiesDirectory, "..", "schemas", "ability-def.schema.json"));
+    }
+}
diff --git a/server/NeonSprawl.Server/Game/Combat/AbilityCatalogServiceCollectionExtensions.cs b/server/NeonSprawl.Server/Game/Combat/AbilityCatalogServiceCollectionExtensions.cs
new file mode 100644
index 0000000..68e7c9f
--- /dev/null
+++ b/server/NeonSprawl.Server/Game/Combat/AbilityCatalogServiceCollectionExtensions.cs
@@ -0,0 +1,37 @@
+using Microsoft.Extensions.Configuration;
+using Microsoft.Extensions.Hosting;
+using Microsoft.Extensions.Options;
+using NeonSprawl.Server.Game.Skills;
+
+namespace NeonSprawl.Server.Game.Combat;
+
+/// <summary>DI registration for the fail-fast ability catalog (NEO-77).</summary>
+public static class AbilityCatalogServiceCollectionExtensions
+{
+    /// <summary>Binds <see cref="ContentPathsOptions"/> and registers <see cref="AbilityDefinitionCatalog"/> as a singleton.</summary>
+    public static IServiceCollection AddAbilityDefinitionCatalog(this IServiceCollection services, IConfiguration configuration)
+    {
+        services.AddOptions<ContentPathsOptions>()
+            .Bind(configuration.GetSection(ContentPathsOptions.SectionName));
+
+        services.AddSingleton<AbilityDefinitionCatalog>(sp =>
+        {
+            var hostEnv = sp.GetRequiredService<IHostEnvironment>();
+            var opts = sp.GetRequiredService<IOptions<ContentPathsOptions>>().Value;
+            var logger = sp.GetRequiredService<ILoggerFactory>()
+                .CreateLogger("NeonSprawl.Server.Game.Combat.AbilityCatalog");
+
+            var abilitiesDir = AbilityCatalogPathResolution.ResolveAbilitiesDirectory(
+                opts.AbilitiesDirectory,
+                hostEnv.ContentRootPath);
+            var schemaPath = AbilityCatalogPathResolution.ResolveAbilityDefSchemaPath(
+                abilitiesDir,
+                opts.AbilityDefSchemaPath,
+                hostEnv.ContentRootPath);
+
+            return AbilityDefinitionCatalogLoader.Load(abilitiesDir, schemaPath, logger);
+        });
+
+        return services;
+    }
+}
diff --git a/server/NeonSprawl.Server/Game/Combat/AbilityDefRow.cs b/server/NeonSprawl.Server/Game/Combat/AbilityDefRow.cs
new file mode 100644
index 0000000..34ff4cb
--- /dev/null
+++ b/server/NeonSprawl.Server/Game/Combat/AbilityDefRow.cs
@@ -0,0 +1,9 @@
+namespace NeonSprawl.Server.Game.Combat;
+
+/// <summary>One validated <c>AbilityDef</c> row from <c>content/abilities/*_abilities.json</c> (NEO-77).</summary>
+public sealed record AbilityDefRow(
+    string Id,
+    string DisplayName,
+    int BaseDamage,
+    double CooldownSeconds,
+    string? AbilityKind);
diff --git a/server/NeonSprawl.Server/Game/Combat/AbilityDefinitionCatalog.cs b/server/NeonSprawl.Server/Game/Combat/AbilityDefinitionCatalog.cs
new file mode 100644
index 0000000..1c5b10f
--- /dev/null
+++ b/server/NeonSprawl.Server/Game/Combat/AbilityDefinitionCatalog.cs
@@ -0,0 +1,24 @@
+using System.Collections.ObjectModel;
+
+namespace NeonSprawl.Server.Game.Combat;
+
+/// <summary>In-memory ability catalog loaded at startup (NEO-77). Game callers should use <c>IAbilityDefinitionRegistry</c> (NEO-79).</summary>
+public sealed class AbilityDefinitionCatalog(
+    string abilitiesDirectory,
+    IReadOnlyDictionary<string, AbilityDefRow> byId,
+    int catalogJsonFileCount)
+{
+    /// <summary>Absolute path to the directory that was enumerated for <c>*_abilities.json</c> catalogs.</summary>
+    public string AbilitiesDirectory { get; } = abilitiesDirectory;
+
+    public IReadOnlyDictionary<string, AbilityDefRow> ById { get; } = new ReadOnlyDictionary<string, AbilityDefRow>(new Dictionary<string, AbilityDefRow>(byId, StringComparer.Ordinal));
+
+    public int DistinctAbilityCount => ById.Count;
+
+    /// <summary>Number of <c>*_abilities.json</c> files under <see cref="AbilitiesDirectory"/>.</summary>
+    public int CatalogJsonFileCount { get; } = catalogJsonFileCount;
+
+    /// <summary>Resolves a catalog row by stable ability <paramref name="id"/>.</summary>
+    public bool TryGetAbility(string id, out AbilityDefRow? row) =>
+        ById.TryGetValue(id, out row);
+}
diff --git a/server/NeonSprawl.Server/Game/Combat/AbilityDefinitionCatalogLoader.cs b/server/NeonSprawl.Server/Game/Combat/AbilityDefinitionCatalogLoader.cs
new file mode 100644
index 0000000..5eb5e83
--- /dev/null
+++ b/server/NeonSprawl.Server/Game/Combat/AbilityDefinitionCatalogLoader.cs
@@ -0,0 +1,190 @@
+using System.Text;
+using System.Text.Json;
+using System.Text.Json.Nodes;
+using Json.Schema;
+using Microsoft.Extensions.Logging;
+
+namespace NeonSprawl.Server.Game.Combat;
+
+/// <summary>Loads and validates <c>content/abilities/*_abilities.json</c> using the same rules as <c>scripts/validate_content.py</c> (NEO-77).</summary>
+public static class AbilityDefinitionCatalogLoader
+{
+    /// <summary>Loads catalogs from disk or throws <see cref="InvalidOperationException"/> with actionable messages.</summary>
+    public static AbilityDefinitionCatalog Load(string abilitiesDirectory, string schemaPath, ILogger logger)
+    {
+        abilitiesDirectory = Path.GetFullPath(abilitiesDirectory);
+        schemaPath = Path.GetFullPath(schemaPath);
+
+        var errors = new List<string>();
+
+        if (!File.Exists(schemaPath))
+            errors.Add($"error: missing schema file {schemaPath}");
+
+        if (!Directory.Exists(abilitiesDirectory))
+            errors.Add($"error: missing directory {abilitiesDirectory}");
+
+        if (errors.Count > 0)
+            ThrowIfAny(errors);
+
+        var jsonFiles = Directory.GetFiles(abilitiesDirectory, "*_abilities.json", SearchOption.TopDirectoryOnly)
+            .OrderBy(p => p, StringComparer.Ordinal)
+            .ToArray();
+        if (jsonFiles.Length == 0)
+            errors.Add($"error: no *_abilities.json files under {abilitiesDirectory}");
+
+        if (errors.Count > 0)
+            ThrowIfAny(errors);
+
+        var schema = JsonSchema.FromText(File.ReadAllText(schemaPath));
+        var evalOptions = new EvaluationOptions { OutputFormat = OutputFormat.List };
+
+        var abilityIdToSourceFile = new Dictionary<string, string>(StringComparer.Ordinal);
+        var rows = new Dictionary<string, AbilityDefRow>(StringComparer.Ordinal);
+
+        foreach (var path in jsonFiles)
+        {
+            JsonNode? root;
+            try
+            {
+                root = JsonNode.Parse(File.ReadAllText(path));
+            }
+            catch (JsonException ex)
+            {
+                errors.Add($"error: {path}: invalid JSON: {ex.Message}");
+                continue;
+            }
+
+            if (root is not JsonObject rootObj)
+            {
+                errors.Add($"error: {path}: expected JSON object at root");
+                continue;
+            }
+
+            var schemaVersionNode = rootObj["schemaVersion"];
+            if (schemaVersionNode is not JsonValue schemaVersionValue ||
+                !schemaVersionValue.TryGetValue<int>(out var schemaVersion) ||
+                schemaVersion != 1)
+            {
+                var got = schemaVersionNode?.ToJsonString() ?? "null";
+                errors.Add($"error: {path}: expected schemaVersion 1, got {got}");
+                continue;
+            }
+
+            var abilitiesNode = rootObj["abilities"];
+            if (abilitiesNode is not JsonArray abilitiesArray)
+            {
+                errors.Add($"error: {path}: expected top-level 'abilities' array");
+                continue;
+            }
+
+            for (var i = 0; i < abilitiesArray.Count; i++)
+            {
+                var ability = abilitiesArray[i];
+                if (ability is not JsonObject rowObj)
+                {
+                    errors.Add($"error: {path}: abilities[{i}] must be an object");
+                    continue;
+                }
+
+                var eval = schema.Evaluate(rowObj, evalOptions);
+                var schemaMsgs = CollectSchemaMessages(eval, path, i).OrderBy(m => m, StringComparer.Ordinal).ToList();
+                if (!eval.IsValid)
+                {
+                    if (schemaMsgs.Count == 0)
+                        schemaMsgs.Add($"error: {path} abilities[{i}] (root): schema validation failed");
+
+                    errors.AddRange(schemaMsgs);
+                }
+
+                var rowSchemaErrors = schemaMsgs.Count;
+
+                var aid = (rowObj["id"] as JsonValue)?.GetValue<string>();
+                if (aid is not null && rowSchemaErrors == 0)
+                {
+                    if (abilityIdToSourceFile.TryGetValue(aid, out var prevPath))
+                    {
+                        errors.Add($"error: duplicate ability id '{aid}' in {prevPath} and {path}");
+                        continue;
+                    }
+
+                    abilityIdToSourceFile[aid] = path;
+                    rows[aid] = ParseRow(rowObj);
+                }
+            }
+        }
+
+        ThrowIfAny(errors);
+
+        var e5m1 = PrototypeE5M1AbilityCatalogRules.TryGetE5M1GateError(abilityIdToSourceFile);
+        if (e5m1 is not null)
+        {
+            errors.Add(e5m1);
+            ThrowIfAny(errors);
+        }
+
+        if (logger.IsEnabled(LogLevel.Information))
+        {
+            logger.LogInformation(
+                "Loaded ability catalog from {AbilitiesDirectory}: {AbilityCount} ability(s) across {CatalogFileCount} JSON catalog file(s).",
+                abilitiesDirectory,
+                rows.Count,
+                jsonFiles.Length);
+        }
+
+        return new AbilityDefinitionCatalog(abilitiesDirectory, rows, jsonFiles.Length);
+    }
+
+    private static AbilityDefRow ParseRow(JsonObject rowObj)
+    {
+        var id = (rowObj["id"] as JsonValue)!.GetValue<string>();
+        var displayName = (rowObj["displayName"] as JsonValue)!.GetValue<string>();
+        var baseDamage = (rowObj["baseDamage"] as JsonValue)!.GetValue<int>();
+        var cooldownSeconds = (rowObj["cooldownSeconds"] as JsonValue)!.GetValue<double>();
+        string? abilityKind = null;
+        if (rowObj["abilityKind"] is JsonValue abilityKindValue)
+            abilityKind = abilityKindValue.GetValue<string>();
+
+        return new AbilityDefRow(id, displayName, baseDamage, cooldownSeconds, abilityKind);
+    }
+
+    private static List<string> CollectSchemaMessages(EvaluationResults eval, string filePath, int index)
+    {
+        var sink = new List<string>();
+        AppendSchemaMessages(eval, filePath, index, sink);
+        return sink;
+    }
+
+    private static void AppendSchemaMessages(EvaluationResults r, string filePath, int index, List<string> sink)
+    {
+        if (r.HasDetails)
+        {
+            foreach (var d in r.Details!)
+                AppendSchemaMessages(d, filePath, index, sink);
+        }
+
+        if (!r.HasErrors)
+            return;
+
+        foreach (var kv in r.Errors!)
+        {
+            var loc = r.InstanceLocation?.ToString();
+            if (string.IsNullOrEmpty(loc) || loc == "#")
+                loc = "(root)";
+
+            sink.Add($"error: {filePath} abilities[{index}] {loc}: {kv.Key} — {kv.Value}");
+        }
+    }
+
+    private static void ThrowIfAny(List<string> errors)
+    {
+        if (errors.Count == 0)
+            return;
+
+        var sb = new StringBuilder();
+        sb.AppendLine("Ability catalog validation failed:");
+        foreach (var e in errors.OrderBy(x => x, StringComparer.Ordinal))
+            sb.AppendLine(e);
+
+        throw new InvalidOperationException(sb.ToString().TrimEnd());
+    }
+}
diff --git a/server/NeonSprawl.Server/Game/Combat/PrototypeE5M1AbilityCatalogRules.cs b/server/NeonSprawl.Server/Game/Combat/PrototypeE5M1AbilityCatalogRules.cs
new file mode 100644
index 0000000..30f8b89
--- /dev/null
+++ b/server/NeonSprawl.Server/Game/Combat/PrototypeE5M1AbilityCatalogRules.cs
@@ -0,0 +1,35 @@
+using System.Collections.Frozen;
+
+namespace NeonSprawl.Server.Game.Combat;
+
+/// <summary>
+/// Prototype E5M1 roster gate (NEO-76 / NEO-77), mirrored from <c>scripts/validate_content.py</c>
+/// <c>PROTOTYPE_E5M1_ABILITY_IDS</c> / <c>_prototype_e5m1_ability_gate</c>.
+/// </summary>
+public static class PrototypeE5M1AbilityCatalogRules
+{
+    /// <summary>Keep in sync with <c>scripts/validate_content.py</c> <c>PROTOTYPE_E5M1_ABILITY_IDS</c>.</summary>
+    public static readonly FrozenSet<string> ExpectedAbilityIds = FrozenSet.ToFrozenSet(
+        [
+            "prototype_pulse",
+            "prototype_guard",
+            "prototype_dash",
+            "prototype_burst",
+        ],
+        StringComparer.Ordinal);
+
+    /// <summary>Returns a human-readable error if the E5M1 ability contract fails, otherwise <see langword="null"/>.</summary>
+    public static string? TryGetE5M1GateError(IReadOnlyDictionary<string, string> abilityIdToSourceFile)
+    {
+        var ids = abilityIdToSourceFile.Keys.ToFrozenSet(StringComparer.Ordinal);
+        if (!ids.SetEquals(ExpectedAbilityIds))
+        {
+            return
+                "error: prototype E5M1 expects exactly ability ids " +
+                $"[{string.Join(", ", ExpectedAbilityIds.Order(StringComparer.Ordinal).Select(s => "'" + s + "'"))}], " +
+                $"got [{string.Join(", ", ids.Order(StringComparer.Ordinal).Select(s => "'" + s + "'"))}]";
+        }
+
+        return null;
+    }
+}
diff --git a/server/NeonSprawl.Server/Game/Skills/ContentPathsOptions.cs b/server/NeonSprawl.Server/Game/Skills/ContentPathsOptions.cs
index 4655375..93da821 100644
--- a/server/NeonSprawl.Server/Game/Skills/ContentPathsOptions.cs
+++ b/server/NeonSprawl.Server/Game/Skills/ContentPathsOptions.cs
@@ -76,4 +76,16 @@ public sealed class ContentPathsOptions
     /// When unset, resolved as <c>{parent of recipes directory}/schemas/recipe-io-row.schema.json</c>.
     /// </summary>
     public string? RecipeIoRowSchemaPath { get; set; }
+
+    /// <summary>
+    /// Optional. Absolute path, or path relative to <see cref="Microsoft.Extensions.Hosting.IHostEnvironment.ContentRootPath"/>.
+    /// When unset, the host walks ancestors of <see cref="AppContext.BaseDirectory"/> for a <c>content/abilities</c> directory.
+    /// </summary>
+    public string? AbilitiesDirectory { get; set; }
+
+    /// <summary>
+    /// Optional override for <c>ability-def.schema.json</c>.
+    /// When unset, resolved as <c>{parent of abilities directory}/schemas/ability-def.schema.json</c>.
+    /// </summary>
+    public string? AbilityDefSchemaPath { get; set; }
 }
diff --git a/server/NeonSprawl.Server/Program.cs b/server/NeonSprawl.Server/Program.cs
index 645dd15..87ae584 100644
--- a/server/NeonSprawl.Server/Program.cs
+++ b/server/NeonSprawl.Server/Program.cs
@@ -1,4 +1,5 @@
 using NeonSprawl.Server.Game.AbilityInput;
+using NeonSprawl.Server.Game.Combat;
 using NeonSprawl.Server.Game.Crafting;
 using NeonSprawl.Server.Game.Gathering;
 using NeonSprawl.Server.Game.Interaction;
@@ -19,6 +20,7 @@ builder.Services.AddSkillDefinitionCatalog(builder.Configuration);
 builder.Services.AddItemDefinitionCatalog(builder.Configuration);
 builder.Services.AddResourceNodeCatalog(builder.Configuration);
 builder.Services.AddRecipeDefinitionCatalog(builder.Configuration);
+builder.Services.AddAbilityDefinitionCatalog(builder.Configuration);
 builder.Services.AddMasteryCatalog(builder.Configuration);
 
 var app = builder.Build();
@@ -26,6 +28,7 @@ _ = app.Services.GetRequiredService<SkillDefinitionCatalog>();
 _ = app.Services.GetRequiredService<ItemDefinitionCatalog>();
 _ = app.Services.GetRequiredService<ResourceNodeCatalog>();
 _ = app.Services.GetRequiredService<RecipeDefinitionCatalog>();
+_ = app.Services.GetRequiredService<AbilityDefinitionCatalog>();
 _ = app.Services.GetRequiredService<MasteryCatalog>();
 _ = app.Services.GetRequiredService<ISkillLevelCurve>();
 
diff --git a/server/NeonSprawl.Server/appsettings.json b/server/NeonSprawl.Server/appsettings.json
index 3e9cd5a..b13ffb7 100644
--- a/server/NeonSprawl.Server/appsettings.json
+++ b/server/NeonSprawl.Server/appsettings.json
@@ -13,7 +13,9 @@
     "ItemDefSchemaPath": "",
     "RecipesDirectory": "",
     "RecipeDefSchemaPath": "",
-    "RecipeIoRowSchemaPath": ""
+    "RecipeIoRowSchemaPath": "",
+    "AbilitiesDirectory": "",
+    "AbilityDefSchemaPath": ""
   },
   "Game": {
     "DevPlayerId": "dev-local-1",
diff --git a/server/README.md b/server/README.md
index d8321d1..0277adf 100644
--- a/server/README.md
+++ b/server/README.md
@@ -80,6 +80,19 @@ On startup the host loads every **`*_recipes.json`** under the recipes directory
 
 On success, **Information** logs include the resolved recipes directory path, distinct recipe count, and catalog file count. Game code should use **`IRecipeDefinitionRegistry`** for lookups (NEO-67). The catalog singleton remains for fail-fast startup only; do not inject **`RecipeDefinitionCatalog`** in new game code.
 
+## Ability catalog (`content/abilities`, NEO-77)
+
+On startup the host loads every **`*_abilities.json`** under the abilities directory, validates each row against **`content/schemas/ability-def.schema.json`**, requires **`schemaVersion` 1** per file, rejects **duplicate `id`** values across files, and enforces the **prototype E5M1** four-id roster gate (same rules as **`scripts/validate_content.py`**). If anything is missing or invalid, the process **exits during startup** with an actionable error—there is no silent fallback.
+
+| Config | Meaning |
+|--------|---------|
+| **`Content:AbilitiesDirectory`** | Optional. Absolute path, or path relative to the server **content root**. When unset, walks **ancestors of `AppContext.BaseDirectory`** until it finds **`content/abilities`**. |
+| **`Content:AbilityDefSchemaPath`** | Optional override for **`ability-def.schema.json`**. When unset, **`{parent of abilities directory}/schemas/ability-def.schema.json`**. |
+
+**Docker / CI:** include **`content/abilities`** and **`content/schemas/ability-def.schema.json`** in the mounted **`content/`** tree; set **`Content__AbilitiesDirectory`** when layout differs.
+
+On success, **Information** logs include the resolved abilities directory path, distinct ability count, and catalog file count. Game code should use **`IAbilityDefinitionRegistry`** for lookups (NEO-79). The catalog singleton remains for fail-fast startup only; **`PrototypeAbilityRegistry`** hotbar/cast allowlist is unchanged until NEO-79.
+
 ## Recipe definitions (NEO-68)
 
 **`GET /game/world/recipe-definitions`** returns a versioned JSON body (`schemaVersion` **1**, **`recipes`**) backed by **`IRecipeDefinitionRegistry`** — the same prototype rows loaded at startup (no second source of truth). Each row includes **`id`**, **`displayName`**, **`recipeKind`**, **`requiredSkillId`**, and nested **`inputs`** / **`outputs`** (`itemId`, `quantity`). Plan: [NEO-68 implementation plan](../../docs/plans/NEO-68-implementation-plan.md); manual QA: [`docs/manual-qa/NEO-68.md`](../../docs/manual-qa/NEO-68.md); Bruno: `bruno/neon-sprawl-server/recipe-definitions/`.