Comment on diff to give agent context

[maskdotdev]

I'm aware that this is a large PR, and a big no no per the Contributing.md..., will be opening anyways since it may serve as a basis as Julius mentioned 🫡 .

closes #79

Here's a video of how it would work:

t3code-diff-context.mp4

This PR would cover:

• Select lines in the diff panel and attach draft comments to a specific file and line range.
• Those pending diff comments show up in the composer as attached context, just like we do with images.
• Sending a message includes the diff comments as structured prompt context for the model, with line range, file path, etc.
• The chat timeline hides that raw structured block and shows it as a compact "comments attached" indicator instead.
• Pending diff comments can be edited or deleted from the diff view before send.
• Draft comments persist in composer draft state and recover correctly across failed sends.

Checklist

• This PR is small and focused
• I explained what changed and why
• I included a video for animation/interaction changes

Note

Add diff-context comments to agent chat turns

• Users can select lines in the diff panel to create, edit, and delete pending diff-context comments, which appear as inline annotations on the diff.
• Pending comments are tracked in the composer draft store with full CRUD support and are persisted across sessions.
• When sending a message, pending diff-context comments are serialized as a <diff_context_comments> block appended to the outgoing message text; a message consisting solely of diff comments can be sent.
• The composer shows a summary pill (ComposerPendingDiffComments.tsx) for pending comments with a clear-all control.
• User message bubbles in the timeline strip the serialized block and show a count indicator with tooltip instead; copy and height estimation also exclude the block.

^{Macroscope summarized fac67c6.}

[coderabbitai]

Important

Review skipped

Auto reviews are disabled on this repository. Please check the settings in the CodeRabbit UI or the .coderabbit.yaml file in this repository. To trigger a single review, invoke the @coderabbitai review command.

⚙️ Run configuration

Configuration used: Repository UI

Review profile: CHILL

Plan: Pro

Run ID: c360ff53-5d7c-4ce8-aa62-4499dd48d815

You can disable this status message by setting the reviews.review_status to false in the CodeRabbit configuration file.

Use the checkbox below for a quick retry:

• 🔍 Trigger review

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Post copyable unit tests in a comment

📝 Coding Plan

• Generate coding plan for human review comments

---

Thanks for using CodeRabbit! It's free for OSS, and your support helps us grow. If you like it, consider giving us a shout-out.

❤️ Share

• X
• Mastodon
• Reddit
• LinkedIn

_{Comment @coderabbitai help to get the list of available commands and usage tips.}