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

[ethanyhou]

1. Create SKILL.md files across directories:

    '.github/skills/**/SKILL.md',
    '.claude/skills/**/SKILL.md',
    '.agents/skills/**/SKILL.md',
    '~/.copilot/skills/**/SKILL.md',
    '~/.claude/skills/**/SKILL.md',
    '~/.agents/skills/**/SKILL.md'

2. Go to preference page to enable the skill:
   
3. Switch to agent mode and type /, the skills should be rendered / hide corresponding to the preference settings.
   
4. Skills is only enabled in agent mode, this is a CLS side behavior.

[Copilot]

Pull request overview

Adds Skills support to Copilot Chat’s Agent experience by wiring a new “Enable Skills” preference through to CLS settings, extending the conversation templates LSP request to include workspace folders (so CLS can discover SKILL.md / .prompt.md), and updating UI/test infrastructure to validate skills rendering via SWTBot probes.

Changes:

• Add “Enable Skills” preference (UI strings, preference page UI, defaults) and propagate it to language server settings.
• Extend conversation/templates request to include workspace folders; enrich template model with source (BUILTIN/PROMPT/SKILL) and update completion filtering/sorting.
• Add SWTBot probe actions + a new probe script to validate skills appear/disappear based on the preference.

Reviewed changes

Copilot reviewed 22 out of 22 changed files in this pull request and generated 10 comments.

Show a summary per file

File	Description
com.microsoft.copilot.eclipse.ui/src/com/microsoft/copilot/eclipse/ui/preferences/messages.properties	Adds UI strings for Skills toggle; adjusts sub-agent label.
com.microsoft.copilot.eclipse.ui/src/com/microsoft/copilot/eclipse/ui/preferences/Messages.java	Adds NLS keys for Skills toggle.
com.microsoft.copilot.eclipse.ui/src/com/microsoft/copilot/eclipse/ui/preferences/LanguageServerSettingManager.java	Syncs enableSkills to CLS settings, including live updates.
com.microsoft.copilot.eclipse.ui/src/com/microsoft/copilot/eclipse/ui/preferences/CopilotPreferenceInitializer.java	Sets default values for sub-agent + skills toggles.
com.microsoft.copilot.eclipse.ui/src/com/microsoft/copilot/eclipse/ui/preferences/ChatPreferencesPage.java	Adds “Enable Skills” field editor; refactors layout helpers.
com.microsoft.copilot.eclipse.ui/src/com/microsoft/copilot/eclipse/ui/chat/services/ChatCompletionService.java	Refreshes templates using workspace folders; listens for skill/prompt file changes + pref changes.
com.microsoft.copilot.eclipse.ui/src/com/microsoft/copilot/eclipse/ui/chat/ChatAssistProcessor.java	Filters templates by mode scope and improves matching/sorting; displays skills using short description.
com.microsoft.copilot.eclipse.ui.test/src/com/microsoft/copilot/eclipse/ui/preferences/LanguageServerSettingManagerTests.java	Updates mocks for the new preference key.
com.microsoft.copilot.eclipse.ui.test/src/com/microsoft/copilot/eclipse/ui/chat/services/McpExtensionPointManagerTest.java	Fixes test setup to avoid NPE; improves null-map assertion.
com.microsoft.copilot.eclipse.ui.test/src/com/microsoft/copilot/eclipse/ui/chat/services/ChatCompletionServiceTest.java	Updates tests for new templates API + job family; adds static mocking of CopilotUi.
com.microsoft.copilot.eclipse.swtbot.test/src/com/microsoft/copilot/eclipse/swtbot/test/probe/StepExecutor.java	Adds new probe actions (preferences, workspace file ops, job waiting, content-assist assertions, key typing).
com.microsoft.copilot.eclipse.swtbot.test/src/com/microsoft/copilot/eclipse/swtbot/test/probe/ProbeStep.java	Adds fields needed for the new probe actions.
com.microsoft.copilot.eclipse.swtbot.test/src/com/microsoft/copilot/eclipse/swtbot/test/probe/Locator.java	Documents new checkBox locator type.
com.microsoft.copilot.eclipse.swtbot.test/probe-scripts/skills-file-with-pref-001.json	New probe validating Skills enabled/disabled behavior.
com.microsoft.copilot.eclipse.core/src/com/microsoft/copilot/eclipse/core/lsp/protocol/TemplateSource.java	New enum identifying template source type.
com.microsoft.copilot.eclipse.core/src/com/microsoft/copilot/eclipse/core/lsp/protocol/CopilotAgentSettings.java	Adds enableSkills setting.
com.microsoft.copilot.eclipse.core/src/com/microsoft/copilot/eclipse/core/lsp/protocol/ConversationTemplatesParams.java	New params record for conversation/templates request.
com.microsoft.copilot.eclipse.core/src/com/microsoft/copilot/eclipse/core/lsp/protocol/ConversationTemplate.java	Converts template model to a record; adds source.
com.microsoft.copilot.eclipse.core/src/com/microsoft/copilot/eclipse/core/lsp/CopilotLanguageServerConnection.java	Updates listConversationTemplates to pass workspace folders.
com.microsoft.copilot.eclipse.core/src/com/microsoft/copilot/eclipse/core/lsp/CopilotLanguageServer.java	Updates LSP request signature for templates to accept params.
com.microsoft.copilot.eclipse.core/src/com/microsoft/copilot/eclipse/core/Constants.java	Adds ENABLE_SKILLS preference key.
.github/skills/ui-action/SKILL.md	Documents new probe actions used by the skills probe script.

Comments suppressed due to low confidence (2)

com.microsoft.copilot.eclipse.ui/src/com/microsoft/copilot/eclipse/ui/chat/services/ChatCompletionService.java:120

• InterruptedException is caught and only logged here. The thread interrupt flag should be restored (Thread.currentThread().interrupt()) so callers/framework code can react appropriately (e.g., job cancellation).

    } catch (InterruptedException | ExecutionException e) {
      CopilotCore.LOGGER.error(e);
    }

com.microsoft.copilot.eclipse.ui/src/com/microsoft/copilot/eclipse/ui/chat/services/ChatCompletionService.java:234

• syncCommands() mutates the current HashSet/ArrayList instances via clear(). Since fetchAsync() updates these fields from a background Job, readers (e.g., isCommand() from the UI thread) can race with clear(), and HashSet/ArrayList are not thread-safe for concurrent reads+writes. Prefer swapping in new immutable/empty instances (e.g., Collections.emptySet()/emptyList()) to keep the snapshot swap pattern consistent and avoid concurrent mutation.

  private void syncCommands(String status) {
    switch (status) {
      case CopilotStatusResult.OK:
        fetchAsync();
        break;
      default:
        allCommands.clear();
        templates.clear();
        agents.clear();
        break;

[kwin]

Looking forward to it, however README should probably updated as well for this feature.

[ethanyhou]

Looking forward to it, however README should probably updated as well for this feature.

@kwin added.