[Feature]: Edit saved review comments in the diff panel and file preview

[cmaciasjimenez]

Before submitting

• I searched existing issues and did not find a duplicate.
• I am describing a concrete problem or use case, not just a vague idea.

Area

apps/web

Problem or use case

Once I submit a review comment on a diff line or in a file preview, its text can't be changed. When I hover a saved comment, the only option is delete. So when I spot a typo, or want to sharpen the instruction before sending the turn, I have to delete the comment, select the same lines again and type the whole thing from scratch.

I ran into this in real use. I wanted to change a comment I'd already left, and the only option was to delete it and start over.

Editing a review comment after you've written it is standard elsewhere. GitHub, GitLab and Codex all let you edit a line comment in place. T3 Code already does this for comments posted to a pull request host (pullRequests.updateComment), so local review comments are the only kind that can't be edited.

Proposed solution

Add an edit (pencil) action next to the existing delete action on a saved review comment. It reopens the same inline composer the comment was written in, prefilled with its text, with Cancel and Save:

• Cancel (or Escape) throws the rewrite away and leaves the saved comment as it was.
• Save replaces the comment's text in place. The comment keeps its id, its line anchor and its position among the draft's attached context.

Why this matters

Review comments are how you give an agent precise, line-anchored feedback. Being able to correct them before sending is basic for a review surface, and it avoids the delete-and-rewrite loop, which is slow and can lose the original wording.

Smallest useful scope

• Web/desktop only, for saved local review comments in the thread diff panel and the file preview.
• No contract, server or mobile changes. Review comments are composer-draft state, and mobile already merges them into the draft text.
• Out of scope: pending (unsubmitted) pull-request review comments, comment threads, resolution state.

Alternatives considered

• Delete and re-add the comment. That's what happens today. It works, but you have to select the lines again and retype the text, and the comment moves to the end of the draft's context.

Risks or tradeoffs

• One extra hover action on saved comments.
• addReviewComment already replaces a record with a matching id, but it does so by removing it and appending it again, which reorders the comments. Editing would change it to replace in place. This changes how shared composer state behaves, so it should have a focused test (feat(web): edit saved review comments in place #12087 adds one).

Examples or references

• Reference implementation with before/after screenshots and a recording: feat(web): edit saved review comments in place #12087. It was closed pending this discussion.
• pullRequests.updateComment: existing editing for comments posted to a PR host.

Contribution

• I would be open to helping implement this.