[FEATURE] Support one-time and n-time delayed task execution in Cowork

Problem Statement

Currently, Cowork only supports two task modes: recurring (scheduled by frequency, e.g., daily/weekly) and manual (triggered by the user). There is no way to schedule a task to execute once on a specific date or to run a limited number of times (n-times).

For example, I want to schedule a code review or a report generation for a specific day of the month — say, March 15th — without it repeating. Right now, the only option is to set it as "manual" and remember to trigger it myself, which defeats the purpose of scheduling.

Reference: Schedule recurring tasks in Cowork

Proposed Solution

• Add a "one-time" schedule option: run the task once at a specified date/time, then mark it as completed.
• Add an "n-times" option: allow specifying the number of executions (e.g., run 3 times on the 1st of each month, then stop).
• Optionally, support a specific calendar date picker (e.g., "run on 2026-03-15 at 10:00 UTC").

Alternative Solutions

• Currently using "manual" mode and manually triggering the task on the desired day.
• Setting a recurring task and manually disabling it after the first run — error-prone and wasteful.

Priority

Medium - Would be very helpful

Feature Category

Other (Cowork scheduling)

Use Case Example

1. I have a monthly report that needs to be generated on a specific date (e.g., the 15th).
2. I create a Cowork task and set it to run once on March 15, 2026.
3. Cowork executes the task on that date and marks it as completed.
4. No need to remember to trigger it manually or clean up a recurring schedule after one run.

Another scenario: I need a task to run on the 1st of the next 3 months only. I set n=3 with monthly frequency. After 3 executions, the task auto-completes.