feat: Support agent skills in agent mode and add preferences settings

.github/skills/ui-action/SKILL.md

@@ -296,4 +296,4 @@ action is usable from every probe.
 ### Keep one probe focused
 
 Each JSON script represents one test case. Split unrelated behaviours into
-separate probes so a single `FAILED-step…` screenshot tells you what broke.
+separate probes so a single `FAILED-step…` screenshot tells you what broke.

README.md

@@ -61,6 +61,18 @@ MCP support enables integrating external tools and services into Copilot workflo
 - **Custom Agents** allow users to create personalized agents with specific instructions and behaviors.
 - **Isolated Subagents** can be spawned by the main agent to handle specific tasks or contexts independently.
 - **Plan Agent** can generate multi-step plans to accomplish complex tasks, breaking them down into manageable actions.
+- **Skills** are reusable, specialized AI assistant templates that enrich chat context in Agent Mode. Skills are defined as `SKILL.md` files and can be scoped to a workspace or shared globally.
+
+  - Creating Skills
+
+    Place a `SKILL.md` file in any of these directories:
+
+    - **Project-scoped:** `.github/skills/<skill-name>/`, `.claude/skills/<skill-name>/`, `.agents/skills/<skill-name>/`
+    - **User-scoped (global):** `~/.copilot/skills/<skill-name>/`, `~/.claude/skills/<skill-name>/`, `~/.agents/skills/<skill-name>/`
+
+    Each `SKILL.md` file can include YAML front matter with metadata (name, description) followed by Markdown content that provides domain knowledge, workflows, or instructions for the AI assistant.
+
+    Skills are automatically discovered and available in Agent Mode. You can enable or disable skills in **Window → Preferences → Copilot → Chat → Enable Skills**.
 
 For other available features in Eclipse, see the [Copilot feature matrix](https://docs.github.com/en/copilot/reference/copilot-feature-matrix?tool=eclipse).
 

com.microsoft.copilot.eclipse.core/src/com/microsoft/copilot/eclipse/core/Constants.java

@@ -28,6 +28,7 @@ private Constants() {
   public static final String WORKSPACE_CONTEXT_ENABLED = "workspaceContextEnabled";
   public static final String SUB_AGENT_ENABLED = "subAgentEnabled";
   public static final String AGENT_MAX_REQUESTS = "agentMaxRequests";
+  public static final String ENABLE_SKILLS = "enableSkills";
   public static final String MCP = "mcp";
   public static final String MCP_REGISTRY_URL = "mcpRegistryUrl";
   public static final String MCP_REGISTRY_VERSION = "v0.1";

com.microsoft.copilot.eclipse.core/src/com/microsoft/copilot/eclipse/core/events/CopilotEventConstants.java

@@ -160,4 +160,10 @@ public class CopilotEventConstants {
    * Event when a rate limit warning is received from the language server.
    */
   public static final String TOPIC_RATE_LIMIT_WARNING = TOPIC_CHAT + "RATE_LIMIT_WARNING";
+
+  /**
+   * Event when custom prompts, skills, agents, or instructions change on the language server. Clients should re-fetch
+   * conversation templates on receipt.
+   */
+  public static final String TOPIC_CHAT_DID_CHANGE_CUSTOMIZATION_FILES = TOPIC_CHAT + "DID_CHANGE_CUSTOMIZATION_FILES";
 }

com.microsoft.copilot.eclipse.core/src/com/microsoft/copilot/eclipse/core/lsp/CopilotLanguageClient.java

@@ -136,11 +136,11 @@ public CompletableFuture<Object[]> getConversationContext(ConversationContextPar
   public CompletableFuture<Object> invokeClientTool(InvokeClientToolParams params) {
     return CompletableFuture.supplyAsync(() -> {
       try {
-        CompletableFuture<LanguageModelToolResult[]> toolFuture =
-            CopilotCore.getPlugin().getChatEventsManager().invokeAgentTool(params);
+        CompletableFuture<LanguageModelToolResult[]> toolFuture = CopilotCore.getPlugin().getChatEventsManager()
+            .invokeAgentTool(params);
         if (toolFuture == null) {
-          CopilotCore.LOGGER.error(
-              new IllegalStateException("invokeAgentTool returned null for tool: " + params.getName()));
+          CopilotCore.LOGGER
+              .error(new IllegalStateException("invokeAgentTool returned null for tool: " + params.getName()));
           LanguageModelToolResult errorResult = new LanguageModelToolResult();
           errorResult.addContent("Failed to invoke the tool: tool invocation returned null");
           errorResult.setStatus(ToolInvocationStatus.error);
@@ -178,6 +178,8 @@ public CompletableFuture<Object[]> confirmClientTool(InvokeClientToolConfirmatio
     });
   }
 
+  // TODO: Should remove workspace-root folder as the projects are not directly under it in Eclipse, and can cause
+  // confusion in CLS.
   @Override
   public CompletableFuture<List<WorkspaceFolder>> workspaceFolders() {
     // Ideally, we should return each IProject as a workspace folder, but given that when
@@ -255,9 +257,30 @@ public void onRateLimitWarning(RateLimitWarningParams params) {
   }
 
   /**
-   * Handles the Dynamic OAuth request for MCP.
-   * Shows a dialog with multiple input fields and returns the user's input values.
-   * Returns null if the user cancels the request.
+   * Notify when custom skills change (global or workspace). Signal-only; clients re-fetch templates.
+   */
+  @JsonNotification("copilot/customSkill/didChange")
+  public void onDidChangeCustomSkill(Object params) {
+    notifyCustomizationFilesChanged();
+  }
+
+  /**
+   * Notify when custom prompts change (global or workspace). Signal-only; clients re-fetch templates.
+   */
+  @JsonNotification("copilot/customPrompt/didChange")
+  public void onDidChangeCustomPrompt(Object params) {
+    notifyCustomizationFilesChanged();
+  }
+
+  private void notifyCustomizationFilesChanged() {
+    if (eventBroker != null) {
+      eventBroker.post(CopilotEventConstants.TOPIC_CHAT_DID_CHANGE_CUSTOMIZATION_FILES, null);
+    }
+  }
+
+  /**
+   * Handles the Dynamic OAuth request for MCP. Shows a dialog with multiple input fields and returns the user's input
+   * values. Returns null if the user cancels the request.
    */
   @JsonRequest("copilot/dynamicOAuth")
   public CompletableFuture<Map<String, String>> mcpOauth(McpOauthRequest request) {
@@ -303,13 +326,11 @@ public void onDidChangePolicy(DidChangePolicyParams params) {
       }
       if (flags.isSubAgentPolicyEnabled() != params.isSubAgentEnabled()) {
         flags.setSubAgentPolicyEnabled(params.isSubAgentEnabled());
-        eventBroker.post(CopilotEventConstants.TOPIC_DID_CHANGE_SUB_AGENT_POLICY,
-            params.isSubAgentEnabled());
+        eventBroker.post(CopilotEventConstants.TOPIC_DID_CHANGE_SUB_AGENT_POLICY, params.isSubAgentEnabled());
       }
       if (flags.isCustomAgentPolicyEnabled() != params.isCustomAgentEnabled()) {
         flags.setCustomAgentPolicyEnabled(params.isCustomAgentEnabled());
-        eventBroker.post(CopilotEventConstants.TOPIC_DID_CHANGE_CUSTOM_AGENT_POLICY,
-            params.isCustomAgentEnabled());
+        eventBroker.post(CopilotEventConstants.TOPIC_DID_CHANGE_CUSTOM_AGENT_POLICY, params.isCustomAgentEnabled());
       }
     }
   }

com.microsoft.copilot.eclipse.core/src/com/microsoft/copilot/eclipse/core/lsp/CopilotLanguageServer.java

@@ -28,6 +28,7 @@
 import com.microsoft.copilot.eclipse.core.lsp.protocol.ConversationMode;
 import com.microsoft.copilot.eclipse.core.lsp.protocol.ConversationModesParams;
 import com.microsoft.copilot.eclipse.core.lsp.protocol.ConversationTemplate;
+import com.microsoft.copilot.eclipse.core.lsp.protocol.ConversationTemplatesParams;
 import com.microsoft.copilot.eclipse.core.lsp.protocol.ConversationTurnParams;
 import com.microsoft.copilot.eclipse.core.lsp.protocol.CopilotModel;
 import com.microsoft.copilot.eclipse.core.lsp.protocol.CopilotStatusResult;
@@ -137,9 +138,11 @@ public interface CopilotLanguageServer extends LanguageServer {
 
   /**
    * List conversation templates.
+   *
+   * @param params includes workspace folders for discovering workspace-specific prompt files and skills
    */
   @JsonRequest("conversation/templates")
-  CompletableFuture<ConversationTemplate[]> listTemplates(NullParams param);
+  CompletableFuture<ConversationTemplate[]> listTemplates(ConversationTemplatesParams params);
 
   /**
    * List conversation modes.

com.microsoft.copilot.eclipse.core/src/com/microsoft/copilot/eclipse/core/lsp/CopilotLanguageServerConnection.java

@@ -20,6 +20,7 @@
 import org.eclipse.lsp4j.ProgressParams;
 import org.eclipse.lsp4j.Range;
 import org.eclipse.lsp4j.TextDocumentIdentifier;
+import org.eclipse.lsp4j.WorkspaceFolder;
 import org.eclipse.lsp4j.jsonrpc.Endpoint;
 import org.eclipse.lsp4j.jsonrpc.messages.Either;
 import org.eclipse.lsp4j.services.LanguageServer;
@@ -45,6 +46,7 @@
 import com.microsoft.copilot.eclipse.core.lsp.protocol.ConversationMode;
 import com.microsoft.copilot.eclipse.core.lsp.protocol.ConversationModesParams;
 import com.microsoft.copilot.eclipse.core.lsp.protocol.ConversationTemplate;
+import com.microsoft.copilot.eclipse.core.lsp.protocol.ConversationTemplatesParams;
 import com.microsoft.copilot.eclipse.core.lsp.protocol.ConversationTurnParams;
 import com.microsoft.copilot.eclipse.core.lsp.protocol.CopilotModel;
 import com.microsoft.copilot.eclipse.core.lsp.protocol.CopilotStatusResult;
@@ -369,10 +371,12 @@ public CompletableFuture<ChatTurnResult> addConversationTurn(String workDoneToke
 
   /**
    * List the conversation templates.
+   *
+   * @param workspaceFolders workspace folders for discovering workspace-specific prompt files and skills
    */
-  public CompletableFuture<ConversationTemplate[]> listConversationTemplates() {
+  public CompletableFuture<ConversationTemplate[]> listConversationTemplates(List<WorkspaceFolder> workspaceFolders) {
     Function<LanguageServer, CompletableFuture<ConversationTemplate[]>> fn = server -> {
-      return ((CopilotLanguageServer) server).listTemplates(new NullParams());
+      return ((CopilotLanguageServer) server).listTemplates(new ConversationTemplatesParams(workspaceFolders));
     };
     return this.languageServerWrapper.execute(fn);
   }

com.microsoft.copilot.eclipse.core/src/com/microsoft/copilot/eclipse/core/lsp/protocol/ConversationTemplate.java

@@ -4,78 +4,14 @@
 package com.microsoft.copilot.eclipse.core.lsp.protocol;
 
 import java.util.List;
-import java.util.Objects;
-
-import org.apache.commons.lang3.builder.ToStringBuilder;
 
 /**
- * Get the templates.
+ * Represents a conversation template returned by the language server.
  */
-public class ConversationTemplate {
-
-
-  private String id;
-  private String description;
-  private String shortDescription;
-  private List<String> scopes;
-
-  public String getId() {
-    return id;
-  }
-
-  public void setId(String id) {
-    this.id = id;
-  }
-
-  public String getDescription() {
-    return description;
-  }
-
-  public void setDescription(String description) {
-    this.description = description;
-  }
-
-  public String getShortDescription() {
-    return shortDescription;
-  }
-
-  public void setShortDescription(String shortDescription) {
-    this.shortDescription = shortDescription;
-  }
-
-  public List<String> getScopes() {
-    return scopes;
-  }
-
-  public void setScopes(List<String> scopes) {
-    this.scopes = scopes;
-  }
-
-  @Override
-  public int hashCode() {
-    return Objects.hash(id, description, shortDescription, scopes);
-  }
-
-  @Override
-  public boolean equals(Object obj) {
-    if (this == obj) {
-      return true;
-    }
-    if (obj == null || getClass() != obj.getClass()) {
-      return false;
-    }
-    ConversationTemplate that = (ConversationTemplate) obj;
-    return Objects.equals(id, that.id) && Objects.equals(description, that.description)
-        && Objects.equals(shortDescription, that.shortDescription) && Objects.equals(scopes, that.scopes);
-  }
-
-  @Override
-  public String toString() {
-    ToStringBuilder builder = new ToStringBuilder(this);
-    builder.append("id", id);
-    builder.append("description", description);
-    builder.append("shortDescription", shortDescription);
-    builder.append("scopes", scopes);
-    return builder.toString();
-  }
+public record ConversationTemplate(
+    String id,
+    String description,
+    String shortDescription,
+    List<String> scopes,
+    TemplateSource source) {
 }

com.microsoft.copilot.eclipse.core/src/com/microsoft/copilot/eclipse/core/lsp/protocol/ConversationTemplatesParams.java

@@ -0,0 +1,21 @@
+// Copyright (c) Microsoft Corporation.
+// Licensed under the MIT license.
+
+package com.microsoft.copilot.eclipse.core.lsp.protocol;
+
+import java.util.Collections;
+import java.util.List;
+
+import org.eclipse.lsp4j.WorkspaceFolder;
+
+/**
+ * Parameters for the {@code conversation/templates} request.
+ *
+ * @param workspaceFolders the workspace folders used to discover workspace-specific prompt files and skills
+ */
+public record ConversationTemplatesParams(List<WorkspaceFolder> workspaceFolders) {
+  /** Compact constructor that defaults {@code null} workspace folders to an empty list. */
+  public ConversationTemplatesParams {
+    workspaceFolders = workspaceFolders != null ? workspaceFolders : Collections.emptyList();
+  }
+}

com.microsoft.copilot.eclipse.core/src/com/microsoft/copilot/eclipse/core/lsp/protocol/CopilotAgentSettings.java

@@ -15,6 +15,7 @@ public class CopilotAgentSettings {
 
   @SerializedName("maxToolCallingLoop")
   private int agentMaxRequests;
+  private boolean enableSkills;
 
   public int getAgentMaxRequests() {
     return agentMaxRequests;
@@ -24,9 +25,17 @@ public void setAgentMaxRequests(int agentMaxRequests) {
     this.agentMaxRequests = agentMaxRequests;
   }
 
+  public boolean isEnableSkills() {
+    return enableSkills;
+  }
+
+  public void setEnableSkills(boolean enableSkills) {
+    this.enableSkills = enableSkills;
+  }
+
   @Override
   public int hashCode() {
-    return Objects.hash(agentMaxRequests);
+    return Objects.hash(agentMaxRequests, enableSkills);
   }
 
   @Override
@@ -38,13 +47,14 @@ public boolean equals(Object obj) {
       return false;
     }
     CopilotAgentSettings other = (CopilotAgentSettings) obj;
-    return agentMaxRequests == other.agentMaxRequests;
+    return agentMaxRequests == other.agentMaxRequests && enableSkills == other.enableSkills;
   }
 
   @Override
   public String toString() {
     ToStringBuilder builder = new ToStringBuilder(this);
     builder.append("agentMaxRequests", agentMaxRequests);
+    builder.append("enableSkills", enableSkills);
     return builder.toString();
   }
 }

com.microsoft.copilot.eclipse.core/src/com/microsoft/copilot/eclipse/core/lsp/protocol/TemplateSource.java

@@ -0,0 +1,20 @@
+// Copyright (c) Microsoft Corporation.
+// Licensed under the MIT license.
+
+package com.microsoft.copilot.eclipse.core.lsp.protocol;
+
+import com.google.gson.annotations.SerializedName;
+
+/**
+ * Source of a conversation template.
+ */
+public enum TemplateSource {
+  @SerializedName("builtin")
+  BUILTIN,
+
+  @SerializedName("prompt")
+  PROMPT,
+
+  @SerializedName("skill")
+  SKILL
+}