Unify agent skills internal architecture

[pwang347]

No description provided.

[Copilot]

Pull request overview

This pull request unifies the agent skills internal architecture by integrating skills into the existing prompt file provider system. Skills are now treated as a first-class prompt type alongside prompts, instructions, and agents.

Key changes:

• Adds SkillProvider API to the proposed extension API for registering skill providers
• Integrates PromptsType.skill into the type system and all related switch statements
• Implements NewSkillFileAction for creating new skill files with validation

Reviewed changes

Copilot reviewed 9 out of 10 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
src/vscode-dts/vscode.proposed.chatPromptFiles.d.ts	Adds SkillProvider, SkillResource, and SkillContext types with registration method
src/vs/workbench/contrib/chat/common/promptSyntax/utils/promptFilesLocator.ts	Replaces hardcoded 'SKILL.md' string with SKILL_FILENAME constant
src/vs/workbench/contrib/chat/common/promptSyntax/service/promptsServiceImpl.ts	Adds skill activation event handling for PromptsType.skill case
src/vs/workbench/contrib/chat/common/promptSyntax/service/promptsService.ts	Exports SKILL_PROVIDER_ACTIVATION_EVENT constant
src/vs/workbench/contrib/chat/common/promptSyntax/promptTypes.ts	Adds SKILL_LANGUAGE_ID, SKILL_DOCUMENTATION_URL, and PromptsType.skill enum value
src/vs/workbench/contrib/chat/common/promptSyntax/config/promptFileLocations.ts	Adds SKILL_FILENAME constant, SKILLS_DEFAULT_SOURCE_FOLDER, and skill file type detection logic
src/vs/workbench/contrib/chat/common/promptSyntax/config/config.ts	Adds SKILLS_LOCATION_KEY configuration and skill case in getPromptFileLocationsConfigKey
src/vs/workbench/contrib/chat/browser/promptSyntax/newPromptFileActions.ts	Implements NewSkillFileAction with skill name validation and getSkillContentSnippet helper
src/vs/workbench/api/common/extHostChatAgents2.ts	Extends provider map type to include SkillProvider and adds skill handling in switch statements
src/vs/workbench/api/common/extHost.api.impl.ts	Registers registerSkillProvider method in the chat namespace

Comments suppressed due to low confidence (1)

src/vs/workbench/contrib/chat/common/promptSyntax/config/promptFileLocations.ts:184

• Test coverage is missing for getCleanPromptName with SKILL.md files. The test suite should include a test case to verify that getCleanPromptName correctly extracts the name from SKILL.md files (case insensitive), returning 'SKILL' for all variations like 'SKILL.md', 'skill.md', and 'Skill.md'.

	// For SKILL.md files (case insensitive), return 'SKILL'
	if (fileName.toLowerCase() === SKILL_FILENAME.toLowerCase()) {
		return basename(fileUri.path, '.md');
	}