Comment on issues
You can leave a comment on any issue visible to you in Linear.

Overview
Once an issue has been created, all workspace members with access to the issue will be able to comment on the issue.
Basics
Post a comment on an issue
You can easily leave a comment on an issue by clicking into the "Leave a comment…" text box at the bottom of any issue you are viewing. Whereas issue descriptions are instantly visible and saved automatically, you will need to click the Comment button or CMD/CTRL ENTER to post the comment to the issue.
You can attach files to a comment using the paper clip icon or CMD/CTRL SHIFT A.
If you navigate away from the issue before posting your comment, the comment will be saved as a draft locally until you navigate back to the issue and post it.
Comment threads

If you want to respond to a specific comment rather than just leave a new comment directly at the bottom of an issue, you can create a comment thread for this purpose.
Hover over the comment you'd like to respond to and click on the arrow icon in the top right to start a comment thread. If a thread already exists, just click into the text box at the bottom of this comment thread and start crafting your response.
To collapse a comment thread, just click Shift X.
Cmd M to focus comment textbox and start writing a comment
Cmd/Ctrl Enter to post a comment on an issue
Cmd/Ctrl Shift A to upload a file to a comment
Shift R to reply to a comment
Shift X to collapse a thread
Edit an issue comment
If you want to edit an existing comment you wrote on an issue, you can click on the ... icon to the top right of the comment and then select edit. You will need to click save to save any changes you make.
If you try and navigate elsewhere in Linear before saving your changes to an issue comment, we will ask if you would like to discard your changes. You can click cancel if you would like to stay and save your changes before navigating elsewhere.
Further actions
To take action on an existing comment, hover over the comment and click on the … icon to the right of the comment. From here, you can choose to edit the comment, copy a link to the comment, create a new issue or sub-issue from the comment and also delete the comment.
Remember, you can always emoji respond to an existing comment if a new comment isn't necessary. Just click on the emoji icon which appears when you hover over the relevant comment.