refactor: introduce write_todos tool for enhanced task management

- Added a new write_todos tool to facilitate the creation and management of planning lists within the chat interface.
- Updated system prompt with detailed instructions on using the write_todos tool, including usage patterns and restrictions.
- Enhanced the chat message handling to support the new tool, ensuring proper integration and user experience.
- Implemented UI components for displaying and interacting with the planning lists, including progress tracking and status indicators.

surfsense_web/components/tool-ui/plan/schema.ts

@@ -0,0 +1,67 @@
+import { z } from "zod";
+import { ActionSchema } from "../shared/schema";
+
+/**
+ * Todo item status
+ */
+export const TodoStatusSchema = z.enum(["pending", "in_progress", "completed", "cancelled"]);
+export type TodoStatus = z.infer<typeof TodoStatusSchema>;
+
+/**
+ * Single todo item in a plan
+ */
+export const PlanTodoSchema = z.object({
+  id: z.string(),
+  label: z.string(),
+  status: TodoStatusSchema,
+  description: z.string().optional(),
+});
+
+export type PlanTodo = z.infer<typeof PlanTodoSchema>;
+
+/**
+ * Serializable plan schema for tool results
+ */
+export const SerializablePlanSchema = z.object({
+  id: z.string(),
+  title: z.string(),
+  description: z.string().optional(),
+  todos: z.array(PlanTodoSchema).min(1),
+  maxVisibleTodos: z.number().optional(),
+  showProgress: z.boolean().optional(),
+});
+
+export type SerializablePlan = z.infer<typeof SerializablePlanSchema>;
+
+/**
+ * Parse and validate a serializable plan from tool result
+ */
+export function parseSerializablePlan(data: unknown): SerializablePlan {
+  const result = SerializablePlanSchema.safeParse(data);
+  
+  if (!result.success) {
+    console.warn("Invalid plan data:", result.error.issues);
+    
+    // Try to extract basic info for fallback
+    const obj = (data && typeof data === "object" ? data : {}) as Record<string, unknown>;
+    
+    return {
+      id: typeof obj.id === "string" ? obj.id : "unknown",
+      title: typeof obj.title === "string" ? obj.title : "Plan",
+      description: typeof obj.description === "string" ? obj.description : undefined,
+      todos: Array.isArray(obj.todos)
+        ? obj.todos.map((t, i) => ({
+            id: typeof (t as any)?.id === "string" ? (t as any).id : `todo-${i}`,
+            label: typeof (t as any)?.label === "string" ? (t as any).label : "Task",
+            status: TodoStatusSchema.safeParse((t as any)?.status).success
+              ? (t as any).status
+              : "pending",
+            description: typeof (t as any)?.description === "string" ? (t as any).description : undefined,
+          }))
+        : [{ id: "1", label: "No tasks", status: "pending" as const }],
+    };
+  }
+  
+  return result.data;
+}
+