refactor: remove built-in skills and built-in skills mechanism (#11414)

Author: hannesrudolph

packages/types/src/skills.ts

@@ -5,8 +5,8 @@
 export interface SkillMetadata {
 	name: string // Required: skill identifier
 	description: string // Required: when to use this skill
-	path: string // Absolute path to SKILL.md (or "<built-in:name>" for built-in skills)
-	source: "global" | "project" | "built-in" // Where the skill was discovered
+	path: string // Absolute path to SKILL.md
+	source: "global" | "project" // Where the skill was discovered
 	/**
 	 * @deprecated Use modeSlugs instead. Kept for backward compatibility.
 	 * If set, skill is only available in this mode.

packages/types/src/vscode-extension-host.ts

@@ -631,7 +631,7 @@ export interface WebviewMessage {
 	modeConfig?: ModeConfig
 	timeout?: number
 	payload?: WebViewMessagePayload
-	source?: "global" | "project" | "built-in"
+	source?: "global" | "project"
 	skillName?: string // For skill operations (createSkill, deleteSkill, moveSkill, openSkillFile)
 	/** @deprecated Use skillModeSlugs instead */
 	skillMode?: string // For skill operations (current mode restriction)

src/core/auto-approval/index.ts

@@ -151,7 +151,7 @@ export async function checkAutoApproval({
 			return { decision: "approve" }
 		}
 
-		// The skill tool only loads pre-defined instructions from built-in, global, or project skills.
+		// The skill tool only loads pre-defined instructions from global or project skills.
 		// It does not read arbitrary files - skills must be explicitly installed/defined by the user.
 		// Auto-approval is intentional to provide a seamless experience when loading task instructions.
 		if (tool.tool === "skill") {

src/core/prompts/sections/skills.ts

@@ -33,10 +33,7 @@ export async function getSkillsSection(
 		.map((skill) => {
 			const name = escapeXml(skill.name)
 			const description = escapeXml(skill.description)
-			// Only include location for file-based skills (not built-in)
-			// Built-in skills are loaded via the skill tool by name, not by path
-			const isFileBasedSkill = skill.source !== "built-in" && skill.path !== "built-in"
-			const locationLine = isFileBasedSkill ? `\n    <location>${escapeXml(skill.path)}</location>` : ""
+			const locationLine = `\n    <location>${escapeXml(skill.path)}</location>`
 			return `  <skill>\n    <name>${name}</name>\n    <description>${description}</description>${locationLine}\n  </skill>`
 		})
 		.join("\n")

src/core/tools/__tests__/skillTool.spec.ts

@@ -99,7 +99,7 @@ describe("skillTool", () => {
 		)
 	})
 
-	it("should successfully load built-in skill", async () => {
+	it("should successfully load a global skill", async () => {
 		const block: ToolUse<"skill"> = {
 			type: "tool_use" as const,
 			name: "skill" as const,
@@ -113,7 +113,7 @@ describe("skillTool", () => {
 		const mockSkillContent = {
 			name: "create-mcp-server",
 			description: "Instructions for creating MCP servers",
-			source: "built-in",
+			source: "global",
 			instructions: "Step 1: Create the server...",
 		}
 
@@ -127,15 +127,15 @@ describe("skillTool", () => {
 				tool: "skill",
 				skill: "create-mcp-server",
 				args: undefined,
-				source: "built-in",
+				source: "global",
 				description: "Instructions for creating MCP servers",
 			}),
 		)
 
 		expect(mockCallbacks.pushToolResult).toHaveBeenCalledWith(
 			`Skill: create-mcp-server
 Description: Instructions for creating MCP servers
-Source: built-in
+Source: global
 
 --- Skill Instructions ---
 
@@ -158,7 +158,7 @@ Step 1: Create the server...`,
 		const mockSkillContent = {
 			name: "create-mcp-server",
 			description: "Instructions for creating MCP servers",
-			source: "built-in",
+			source: "global",
 			instructions: "Step 1: Create the server...",
 		}
 
@@ -170,7 +170,7 @@ Step 1: Create the server...`,
 			`Skill: create-mcp-server
 Description: Instructions for creating MCP servers
 Provided arguments: weather API server
-Source: built-in
+Source: global
 
 --- Skill Instructions ---
 
@@ -192,7 +192,7 @@ Step 1: Create the server...`,
 		mockSkillsManager.getSkillContent.mockResolvedValue({
 			name: "create-mcp-server",
 			description: "Test",
-			source: "built-in",
+			source: "global",
 			instructions: "Test instructions",
 		})
 
@@ -264,7 +264,7 @@ Step 1: Create the server...`,
 		const mockSkillContent = {
 			name: "create-mcp-server",
 			description: "Test",
-			source: "built-in",
+			source: "global",
 			instructions: "Test instructions",
 		}
 

src/core/webview/__tests__/skillsMessageHandler.spec.ts

@@ -28,7 +28,6 @@ vi.mock("../../../i18n", () => ({
 			"skills:errors.missing_delete_fields": "Missing required fields: skillName or source",
 			"skills:errors.missing_move_fields": "Missing required fields: skillName or source",
 			"skills:errors.skill_not_found": `Skill "${params?.name}" not found`,
-			"skills:errors.cannot_modify_builtin": "Built-in skills cannot be created, deleted, or moved",
 		}
 		return translations[key] || key
 	},
@@ -333,25 +332,6 @@ describe("skillsMessageHandler", () => {
 				"Failed to move skill: Skills manager not available",
 			)
 		})
-
-		it("returns undefined when trying to move a built-in skill", async () => {
-			const provider = createMockProvider(true)
-
-			const result = await handleMoveSkill(provider, {
-				type: "moveSkill",
-				skillName: "test-skill",
-				source: "built-in",
-				newSkillMode: "code",
-			} as WebviewMessage)
-
-			expect(result).toBeUndefined()
-			expect(mockLog).toHaveBeenCalledWith(
-				"Error moving skill: Built-in skills cannot be created, deleted, or moved",
-			)
-			expect(vscode.window.showErrorMessage).toHaveBeenCalledWith(
-				"Failed to move skill: Built-in skills cannot be created, deleted, or moved",
-			)
-		})
 	})
 
 	describe("handleOpenSkillFile", () => {

src/core/webview/skillsMessageHandler.ts

@@ -6,6 +6,8 @@ import type { ClineProvider } from "./ClineProvider"
 import { openFile } from "../../integrations/misc/open-file"
 import { t } from "../../i18n"
 
+type SkillSource = SkillMetadata["source"]
+
 /**
  * Handles the requestSkills message - returns all skills metadata
  */
@@ -36,7 +38,7 @@ export async function handleCreateSkill(
 ): Promise<SkillMetadata[] | undefined> {
 	try {
 		const skillName = message.skillName
-		const source = message.source
+		const source = message.source as SkillSource
 		const skillDescription = message.skillDescription
 		// Support new modeSlugs array or fall back to legacy skillMode
 		const modeSlugs = message.skillModeSlugs ?? (message.skillMode ? [message.skillMode] : undefined)
@@ -45,11 +47,6 @@ export async function handleCreateSkill(
 			throw new Error(t("skills:errors.missing_create_fields"))
 		}
 
-		// Built-in skills cannot be created
-		if (source === "built-in") {
-			throw new Error(t("skills:errors.cannot_modify_builtin"))
-		}
-
 		const skillsManager = provider.getSkillsManager()
 		if (!skillsManager) {
 			throw new Error(t("skills:errors.manager_unavailable"))
@@ -81,19 +78,14 @@ export async function handleDeleteSkill(
 ): Promise<SkillMetadata[] | undefined> {
 	try {
 		const skillName = message.skillName
-		const source = message.source
+		const source = message.source as SkillSource
 		// Support new skillModeSlugs array or fall back to legacy skillMode
 		const skillMode = message.skillModeSlugs?.[0] ?? message.skillMode
 
 		if (!skillName || !source) {
 			throw new Error(t("skills:errors.missing_delete_fields"))
 		}
 
-		// Built-in skills cannot be deleted
-		if (source === "built-in") {
-			throw new Error(t("skills:errors.cannot_modify_builtin"))
-		}
-
 		const skillsManager = provider.getSkillsManager()
 		if (!skillsManager) {
 			throw new Error(t("skills:errors.manager_unavailable"))
@@ -122,19 +114,14 @@ export async function handleMoveSkill(
 ): Promise<SkillMetadata[] | undefined> {
 	try {
 		const skillName = message.skillName
-		const source = message.source
+		const source = message.source as SkillSource
 		const currentMode = message.skillMode
 		const newMode = message.newSkillMode
 
 		if (!skillName || !source) {
 			throw new Error(t("skills:errors.missing_move_fields"))
 		}
 
-		// Built-in skills cannot be moved
-		if (source === "built-in") {
-			throw new Error(t("skills:errors.cannot_modify_builtin"))
-		}
-
 		const skillsManager = provider.getSkillsManager()
 		if (!skillsManager) {
 			throw new Error(t("skills:errors.manager_unavailable"))
@@ -163,18 +150,13 @@ export async function handleUpdateSkillModes(
 ): Promise<SkillMetadata[] | undefined> {
 	try {
 		const skillName = message.skillName
-		const source = message.source
+		const source = message.source as SkillSource
 		const newModeSlugs = message.newSkillModeSlugs
 
 		if (!skillName || !source) {
 			throw new Error(t("skills:errors.missing_update_modes_fields"))
 		}
 
-		// Built-in skills cannot be modified
-		if (source === "built-in") {
-			throw new Error(t("skills:errors.cannot_modify_builtin"))
-		}
-
 		const skillsManager = provider.getSkillsManager()
 		if (!skillsManager) {
 			throw new Error(t("skills:errors.manager_unavailable"))
@@ -200,17 +182,12 @@ export async function handleUpdateSkillModes(
 export async function handleOpenSkillFile(provider: ClineProvider, message: WebviewMessage): Promise<void> {
 	try {
 		const skillName = message.skillName
-		const source = message.source
+		const source = message.source as SkillSource
 
 		if (!skillName || !source) {
 			throw new Error(t("skills:errors.missing_delete_fields"))
 		}
 
-		// Built-in skills cannot be opened as files (they have no file path)
-		if (source === "built-in") {
-			throw new Error(t("skills:errors.cannot_open_builtin"))
-		}
-
 		const skillsManager = provider.getSkillsManager()
 		if (!skillsManager) {
 			throw new Error(t("skills:errors.manager_unavailable"))

src/i18n/locales/ca/skills.json

@@ -11,8 +11,6 @@
 		"missing_update_modes_fields": "Missing required fields: skillName or source",
 		"manager_unavailable": "Skills manager not available",
 		"missing_delete_fields": "Missing required fields: skillName or source",
-		"skill_not_found": "Skill \"{{name}}\" not found",
-		"cannot_modify_builtin": "Built-in skills cannot be created, deleted, or moved",
-		"cannot_open_builtin": "Built-in skills cannot be opened as files"
+		"skill_not_found": "Skill \"{{name}}\" not found"
 	}
 }