This is a bit of a puzzler for me and I'd like to try to work out what our community norms and guidelines are around this topic.
Suppose user A posts a question which is a bit light on context. User B sees this and decides that they want to improve the question so that it might avoid closure/deletion (or in the case it's closed, to push for reopening). The way in which user B does this is by adding a partial attempt to the original question, pursuant to the first suggestion of "including your work" in the guide on how to ask a good question.
When and under what conditions is this appropriate behavior?
On the one hand I understand and appreciate the motivation to improve a question that you like but which is perhaps not quite up to our community standards. On the other, including a solution attempt by someone who's not the OP strikes me as potentially a little dishonest, and contrary to the principle that "[e]ven edits that must make drastic changes should strive to preserve the goals of the post's owner" (this is from the suggested edit review dialog). There's also a potential issue with such an edit occurring after an answer has been submitted: if the added attempt is just the first step of the submitted solution, this feels unsatisfying to me.
Question 2524460: Looking at the edit history, it would seem that this is a fairly large edit which adds a nearly-complete solution to the post and changes the intent of the post from "where can I start on this" to "how do I do this without this particular argument". I'm not really a fan of this.
Question 124663: In this question, I found David Speyer's edit explaining why this question was difficult (essentially "the approach you'd want to take doesn't work because of the following problem") to be a valuable addition to the post, even if it's at least passingly similar to the sort of edit above that ruffles my feathers.
I'd like to explicate our community norms/policies about what sort of edits to add context are appropriate. Answers should address general principles for what sort of context is acceptable to add as an editor to questions by others, how this changes based on the general situation surrounding the question (whether the question is already answered, one's previous interactions with the question, etc) and ideally include discussion of examples (either those I've provided in this post or other posts from MSE) to see the potential effects of proposed guidelines.