fix: make new_task tool definition dynamic based on experimental setting

- Tool description now changes based on newTaskRequireTodos setting
- When disabled: shows todos as (optional)
- When enabled: shows todos as (required) with no mention of configuration
- Added tests to verify dynamic behavior
- Ensures AI models get unambiguous instructions based on current settings

src/core/prompts/tools/__tests__/new-task.spec.ts

@@ -0,0 +1,98 @@
+import { describe, it, expect } from "vitest"
+import { getNewTaskDescription } from "../new-task"
+import { ToolArgs } from "../types"
+
+describe("getNewTaskDescription", () => {
+	it("should show todos as optional when experiment is disabled", () => {
+		const args: ToolArgs = {
+			cwd: "/test",
+			supportsComputerUse: false,
+			experiments: {
+				newTaskRequireTodos: false,
+			},
+		}
+
+		const description = getNewTaskDescription(args)
+
+		// Check that todos is marked as optional
+		expect(description).toContain("todos: (optional)")
+		expect(description).toContain("optional initial todo list")
+
+		// Should not contain any mention of required
+		expect(description).not.toContain("todos: (required)")
+	})
+
+	it("should show todos as required when experiment is enabled", () => {
+		const args: ToolArgs = {
+			cwd: "/test",
+			supportsComputerUse: false,
+			experiments: {
+				newTaskRequireTodos: true,
+			},
+		}
+
+		const description = getNewTaskDescription(args)
+
+		// Check that todos is marked as required
+		expect(description).toContain("todos: (required)")
+		expect(description).toContain("and initial todo list")
+
+		// Should not contain any mention of optional for todos
+		expect(description).not.toContain("todos: (optional)")
+		expect(description).not.toContain("optional initial todo list")
+	})
+
+	it("should default to optional when experiments is undefined", () => {
+		const args: ToolArgs = {
+			cwd: "/test",
+			supportsComputerUse: false,
+			experiments: undefined,
+		}
+
+		const description = getNewTaskDescription(args)
+
+		// Check that todos is marked as optional by default
+		expect(description).toContain("todos: (optional)")
+		expect(description).toContain("optional initial todo list")
+	})
+
+	it("should default to optional when newTaskRequireTodos is undefined", () => {
+		const args: ToolArgs = {
+			cwd: "/test",
+			supportsComputerUse: false,
+			experiments: {},
+		}
+
+		const description = getNewTaskDescription(args)
+
+		// Check that todos is marked as optional by default
+		expect(description).toContain("todos: (optional)")
+		expect(description).toContain("optional initial todo list")
+	})
+
+	it("should always include the example with todos", () => {
+		const argsWithExperimentOff: ToolArgs = {
+			cwd: "/test",
+			supportsComputerUse: false,
+			experiments: {
+				newTaskRequireTodos: false,
+			},
+		}
+
+		const argsWithExperimentOn: ToolArgs = {
+			cwd: "/test",
+			supportsComputerUse: false,
+			experiments: {
+				newTaskRequireTodos: true,
+			},
+		}
+
+		const descriptionOff = getNewTaskDescription(argsWithExperimentOff)
+		const descriptionOn = getNewTaskDescription(argsWithExperimentOn)
+
+		// Both should include the example with todos
+		const examplePattern = /<todos>\s*\[\s*\]\s*Set up auth middleware/s
+		expect(descriptionOff).toMatch(examplePattern)
+		expect(descriptionOn).toMatch(examplePattern)
+	})
+})

src/core/prompts/tools/new-task.ts

@@ -1,14 +1,16 @@
 import { ToolArgs } from "./types"
 
-export function getNewTaskDescription(_args: ToolArgs): string {
+export function getNewTaskDescription(args: ToolArgs): string {
+	const todosRequired = args.experiments?.newTaskRequireTodos === true
+	const todosStatus = todosRequired ? "(required)" : "(optional)"
+
 	return `## new_task
-Description: This will let you create a new task instance in the chosen mode using your provided message and optional initial todo list.
+Description: This will let you create a new task instance in the chosen mode using your provided message${todosRequired ? " and initial todo list" : " and optional initial todo list"}.
 
 Parameters:
 - mode: (required) The slug of the mode to start the new task in (e.g., "code", "debug", "architect").
 - message: (required) The initial user message or instructions for this new task.
-- todos: (optional by default, can be required via experimental setting) The initial todo list in markdown checklist format for the new task.
-	 Note: The 'todos' parameter can be configured to be required through the experimental setting 'newTaskRequireTodos'.
+- todos: ${todosStatus} The initial todo list in markdown checklist format for the new task.
 
 Usage:
 <new_task>