feat: support markdown plans

[elenazherdeva]

Supported Markdown plans, made them Jinja-templated, and allowed passing parameters.

The plan.md file can be in a free format, but the last group of lines that start with “-” is considered the plan.

Some examples:

Example 1:

# plan.md

Here is the python repo

-use {{ dep }}
-use poetry

Here is a plan:

- Open a file
- Run a test
- Setup {{ repo }}

the plan is:

- Open a file
- Run a test
- Setup {{ repo }}

Example 2:

Here is the python repo.

You should follow these steps:

- Open a file
- Run a test
- Setup {{ repo }}

the plan is:

- Open a file
- Run a test
- Setup {{ repo }}

To start a session with a plan:

goose session planned plan.md -p param1:value1 param2:value2

[elenazherdeva]

should we get rid of plan.yaml in the goose session start command?

[lamchau]

just curious: is this our recommended style for multiline strings? what are the trade offs for this over triple-quoted multiline strings or even keeping the markdown as a fixture?

[elenazherdeva]

to be honest, I did it to pass the ruff checks. Not sure if we've discussed it before

[michaelneale]

I like this myself - but would want to see others sure as it kind of is a UX/api change (not that plans are well known). I guess main benefit of yaml is if you had a tool emitting it etc for goose to consume

[lily-de]

do we have to use - or will it also pick up * ? because i tend to use * and I think we should be very explicit to users writing their own plans if a certain formatting is needed. We should also add a page in the docs for custom plans -- I don't think I added one

[elenazherdeva]

yes @lily-de I agree, we should mention it in the docs somehow, because now only the last group of lines that start with “-” is considered the plan

[lukealvoeiro]

LGTM! Some small nits, nothing blocking

[lukealvoeiro]

i can see -p being confusing for plan and params... maybe -a/--args instead? up to you tho!

[lukealvoeiro]

[nit/maybe not even applicable]should we be stripping - from the tasks? Just wondering because if someone happens to type in a plan:

-1:do this 
-2:do that

then that could be inferred as negative numbers which maybe would change the order of events?