Recurrence with a constant due window - calculated from start date

[pointlessone]

I have a repeating task that has its due date crossing month boundary. The window for the task completion is constant. Is there a way to set it up with Tasks?

Example:

• Task starts at 25th of every month
• It can be completed within 10 days

This gives the following dates:

Start	Due
2022-01-25	2022-02-04
2022-02-25	2022-03-07
2022-03-25	2022-04-04
2022-04-25	2022-05-05

As you can see, due date does not fall on the same day of the next month.

And here's what I'm getting with Tasks. The last task is what I wrote and the rest is generated.

• test #task 🔁 every month 🛫 2022-07-25 📅 2022-08-04
• test #task 🔁 every month 🛫 2022-06-24 📅 2022-07-04 ✅ 2022-09-14
• test #task 🔁 every month 🛫 2022-05-25 📅 2022-06-04 ✅ 2022-09-14
• test #task 🔁 every month 🛫 2022-04-24 📅 2022-05-04 ✅ 2022-09-14
• test #task 🔁 every month 🛫 2022-03-25 📅 2022-04-04 ✅ 2022-09-14
• test #task 🔁 every month 🛫 2022-02-22 📅 2022-03-04 ✅ 2022-09-14
• test #task 🔁 every month 🛫 2022-01-25 📅 2022-02-04 ✅ 2022-09-14

As you can see, due date is fixed and start date is moving around.

[claremacrae]

This is the intended behaviour, which is documented here:
https://obsidian-tasks-group.github.io/obsidian-tasks/getting-started/recurring-tasks/#priority-of-dates

Due date is the highest priority date, and if your start date is 10 days earlier, the new task’s start date will be 10 days before the new due date.

Because not all months have the same number of days, your “10 days before” rule will give you different start dates.

[pointlessone]

Would you consider a contribution to change dates priority on a per-task basis for the purpose of recurring task generation?

[claremacrae]

It's not something I'm super keen on. It would complicate the code and, more of a concern, complicate the documentation.

To my knowledge, it's the first complaint along these lines, after 135,000 downloads, so it feels to me like quite a corner case.

I was going to suggest a workaround that, with a good text editor and the pattern you had, it would be very easy to make a year or several's copies of the task, non-recurring, and leave a reminder to repeat the pattern in a few years' time, when you had got through the first batch.

[claremacrae]

Would you consider a contribution to change dates priority on a per-task basis for the purpose of recurring task generation?

I’ve been thinking about it some more. What syntax did you have in mind for the per-task option please?

If you have something in mind that would make sense along side the current recurrence syntax, it would help me to understand what you mean, and how generally applicable it might be.

Thanks in advance.

[pointlessone]

I have a few ideas. I didn't spend much time thinking about it and didn't look at the code so don't know if any of them is viable.

---

1. Keep current dates priority but allow relative expressions for dates. Use the first available concrete date as the anchor for recurring dates calculations.

Example:

• test #task 🔁 every month 🛫 2022-03-25 📅 10 days after ✅ 2022-09-14
• test #task 🔁 every month 🛫 2022-02-25 📅 10 days after ✅ 2022-09-14
• test #task 🔁 every month 🛫 2022-01-25 📅 10 days after ✅ 2022-09-14

Start date is the only concrete date here so it's used for calculation to generate a new task. 10 days after is relative to the highest priority concrete date available and would resolve to a different month day every time.

Alternative relative dates:

• test #task 🔁 every month 🛫 2022-01-25 📅 in 10 days ✅ 2022-09-14
• test #task 🔁 every month 🛫 2022-01-25 📅 10 days later ✅ 2022-09-14

---

2. Add anchor date marker. Allows manually specifying which date is the highest priority.

• test #task 🔁 every month 🛫 2022-03-25! 📅 2022-04-04 ✅ 2022-09-14
• test #task 🔁 every month 🛫 2022-02-25! 📅 2022-03-07 ✅ 2022-09-14
• test #task 🔁 every month 🛫 2022-01-25! 📅 2022-02-04 ✅ 2022-09-14

Alternative syntax: mark the designator.

• test #task 🔁 every month 🛫! 2022-01-25 📅 2022-02-04 ✅ 2022-09-14

Exclamation point was the first idea but a different character/placement can be used:

• test #task 🔁 every month 🛫 @2022-01-25 📅 2022-02-04 ✅ 2022-09-14
• test #task 🔁 every month 🛫 2022-01-25⚓ 📅 2022-02-04 ✅ 2022-09-14

[claremacrae]

We should avoid using the @ symbol. It is already used - and expanded - by some other plugins, like Natural Language Dates.

[claremacrae]

Thank you for the suggestions. Don’t worry about the code. We can make most things happen.

The important thing is that it makes sense to users when read, and is easy to document.

(Sometimes when I’m stuck on how something should look, I write the documentation first, to see if I can express what the behaviour should be in words.)

Another idea to throw in to the mix is to add some more words in the ‘every’ section, maybe

every month after start
every month from start

Let’s keep adding suggestions.

[claremacrae]

OK. We would need to work out where the new text goes in relation to the 'when done' words.

In terms of evaluating how logical the new wording would be, here are some examples:

https://obsidian-tasks-group.github.io/obsidian-tasks/getting-started/recurring-tasks/#examples

🔁 every 3 days
🔁 every 10 days when done
🔁 every weekday (meaning every Mon - Fri)
🔁 every week on Sunday
🔁 every 2 weeks
🔁 every 3 weeks on Friday
🔁 every 2 months
🔁 every month on the 1st
🔁 every month on the last
🔁 every 6 months on the 2nd Wednesday
🔁 every January on the 15th
🔁 every February on the last
🔁 every April and December on the 1st and 24th (meaning every April 1st and December 24th)
🔁 every year

A niggle with the 'from start' or 'after start' ideas is that it could seem to relate to the start of the year, or the start of the month.

[pointlessone]

It can be more explicit and be "from start date" or even "from task start date".

[claremacrae]

So your original task would look like this:

• test #task 🔁 every month from start date 🛫 2022-01-25 📅 2022-02-04

I'll have a think about it. In the meantime, I would welcome more suggestions, if any are forthcoming!

It would have to be an error if there was no start date specified (or scheduled, if the user provided that instead). We don't currently have a way to report errors in task content to users, though that is a separate topic.

[claremacrae]

My concern is I still think it can be easily misunderstood, but I don't have any better ideas right now.

[pointlessone]

I can see how "from" can be confusing. Haw about "with start date priority"? Is there another use of "with" in the recurrence syntax?