feat(traits): add Sign Language trait

Content.Server/Traits/Assorted/LanguageKnowledgeModifierComponent.cs

@@ -0,0 +1,23 @@
+using Content.Shared.Language;
+using Robust.Shared.Serialization.TypeSerializers.Implementations.Custom.Prototype.List;
+
+namespace Content.Server.Traits.Assorted;
+
+/// <summary>
+///     Used for traits that modify entities' language knowledge.
+/// </summary>
+[RegisterComponent]
+public sealed partial class LanguageKnowledgeModifierComponent : Component
+{
+    /// <summary>
+    ///     List of languages this entity will learn to speak.
+    /// </summary>
+    [DataField("speaks")]
+    public List<string> NewSpokenLanguages = new();
+
+    /// <summary>
+    ///     List of languages this entity will learn to understand.
+    /// </summary>
+    [DataField("understands")]
+    public List<string> NewUnderstoodLanguages = new();
+}

Content.Server/Traits/Assorted/LanguageKnowledgeModifierSystem.cs

@@ -0,0 +1,35 @@
+using System.Linq;
+using Content.Shared.Language;
+using Content.Shared.Language.Components;
+
+namespace Content.Server.Traits.Assorted;
+
+public sealed class LanguageKnowledgeModifierSystem : EntitySystem
+{
+    [Dependency] private readonly LanguageSystem _languages = default!;
+
+    public override void Initialize()
+    {
+        base.Initialize();
+        SubscribeLocalEvent<LanguageKnowledgeModifierComponent, ComponentInit>(OnStartup);
+    }
+
+    private void OnStartup(Entity<LanguageKnowledgeModifierComponent> entity, ref ComponentInit args)
+    {
+        if (!TryComp<LanguageKnowledgeComponent>(entity, out var knowledge))
+        {
+            Log.Warning($"Entity {entity.Owner} does not have a LanguageKnowledge but has a LanguageKnowledgeModifier!");
+            return;
+        }
+
+        for (var spokenLanguage in entity.Comp.NewSpokenLanguages)
+        {
+            _languages.AddLanguage(entity, spokenLanguage, true, false, knowledge);
+        }
+
+        for (var understoodLanguage in entity.Comp.NewUnderstoodLanguages)
+        {
+            _languages.AddLanguage(entity, understoodLanguage, false, true, knowledge);
+        }
+    }
+}

Resources/Locale/en-US/traits/traits.ftl

@@ -60,3 +60,8 @@ trait-name-Voracious = Voracious
 trait-description-Voracious =
     Nothing gets between you and your food.
     Your endless consumption of food and drinks is twice as fast.
+
+trait-name-SignLanguage = Sign Language
+trait-description-SignLanguage =
+    You can understand and use sign language, allowing for visual communication.
+    Being mute for any reason still allows you to communicate with sign language.

Resources/Prototypes/Traits/skills.yml

@@ -40,3 +40,14 @@
     - type: ConsumeDelayModifier
       foodDelayMultiplier: 0.5
       drinkDelayMultiplier: 0.5
+
+- type: trait
+  id: SignLanguage
+  category: Visual
+  points: -1
+  components:
+    - type: LanguageKnowledgeModifier
+      speaks:
+        - Sign
+      understands:
+        - Sign