Task Manager with Timed Assignments

Process a finite sequence of operations for an initially empty task manager. Return one row of strings for every operation, in input order. The four levels below are cumulative.

Every operation is a row of strings. Its first entry is the operation name and its second entry is a positive integer timestamp written as a decimal string. Operation timestamps strictly increase. All IDs and task-name comparisons are case-sensitive.

Level 1: Task records

• ["ADD_TASK", timestamp, name, priority]: create a task with the given name and nonnegative priority. Return its ID in one cell. IDs are task_id_1, task_id_2, and so on. Tasks with equal names and priorities are allowed.
• ["UPDATE_TASK", timestamp, taskId, name, priority]: replace an existing task's name and priority. Return ["true"] on success or ["false"] when the task does not exist. Updating a task does not change its creation order.
• ["GET_TASK", timestamp, taskId]: return one compact JSON string with the keys name and then priority, for example ["{\"name\":\"Write tests\",\"priority\":5}"]. Preserve all spaces within the name. For this exercise, encode a quotation mark as \" and a backslash as \\ inside the name; write every other permitted character literally. For this exercise, represent a missing task by an empty row [].

Level 2: Search and ordering

• ["SEARCH_TASKS", timestamp, nameFilter, maxResults]: select current task names containing the exact case-sensitive substring nameFilter. An empty filter matches every task.
• ["LIST_TASKS_SORTED", timestamp, limit]: select all tasks.
• Both operations return task IDs sorted by priority descending, then original numeric creation order ascending. Truncate to the requested limit. A nonpositive limit returns [].

Level 3: Users and timed assignments

• ["ADD_USER", timestamp, userId, quota]: for this exercise, create a user and return ["true"] only if the ID is new. A duplicate ID returns ["false"] and preserves the original quota. A zero quota is allowed.
• ["ASSIGN_TASK", timestamp, taskId, userId, finishTime]: create a separate assignment record for the existing task and user. An assignment is active when it is uncompleted and its interval [assignmentTime, finishTime) contains the current timestamp.
• Return ["false"] if the task or user is missing, if the user's active-assignment quota is full, or, for this exercise, if finishTime <= timestamp. Otherwise, return ["true"].
• The same task may have multiple concurrent assignments, including repeated assignments to the same user. Each active assignment consumes one quota slot independently.
• ["GET_USER_TASKS", timestamp, userId]: return one task ID per currently active assignment to that user, sorted by finish time ascending and then assignment timestamp ascending. Keep duplicate task IDs. For this exercise, a missing user returns [].

Level 4: Completion and overdue assignments

• ["COMPLETE_TASK", timestamp, taskId, userId]: among the matching user's active, uncompleted assignments of this task, complete the one with the earliest assignment timestamp. Return ["true"] and immediately release its quota slot. Return ["false"] if no such record exists.
• An assignment cannot be completed at or after its finish time because its active interval excludes that endpoint.
• ["GET_OVERDUE_ASSIGNMENTS", timestamp, userId]: return one task ID per uncompleted assignment to that user with finishTime <= timestamp. Sort by finish time ascending and then assignment timestamp ascending. Keep duplicate IDs from separate records. For this exercise, a missing user returns [].
• A completed assignment never appears in future active or overdue lists. Queries do not consume or remove records. Changing task metadata does not change existing assignment identity or timestamps.

Output rows

Task creation returns one ID, Boolean operations return one lowercase Boolean string, and an existing-task lookup returns one JSON string. List operations return zero or more task IDs directly as the row's cells. A failed mutation leaves tasks, users, counters, and assignment records unchanged.