feat(comments): reference a comment into the agent, and turn its answer into a reply draft

[huhamhire]

A reviewer''s comment is usually a claim — is this actually a problem, does this path really run, was it handled elsewhere — and settling it means reading the code the comment points at. That is what the agent is for, but the only way to hand it one was to paste the text into the chat box, dropping the anchor and the authorship on the way. And once you had the answer, replying meant retyping it.

What it does

1. Reference — a button on any comment attaches it as implicit context for the next question, so "is this right?" is a complete question. The agent receives the comment body, its author, and the file/line it points at.
2. Reply — the answer carries a use as reply action that turns it into a draft reply to that comment.

No IPC changes

Both halves land on existing contracts, which is most of why this stayed small:

• agent:ask already carries referencedContext for the diff selection. The comment formats into the same channel, and the two compose — asking whether a comment is right about a selected region needs both.
• drafts:create already models a reply through replyTo, and the comment''s anchor carries over, so an inline reply keeps its position in the diff.

Cross-pane state goes in a store for the same reason the diff selection does: the comment surfaces and ChatPane are siblings with no common owner below App.

Three decisions worth reviewing

The association is deliberately short-lived. "Use as reply" needs the answer to know which comment it answers, so a referenced comment hands off on send instead of being discarded — detached from the input bar, still tied to that round. The hand-off runs on every send, including unreferenced ones: that is what ends a previous association, so an unrelated later answer never offers itself as a reply to an old comment. Memory only, one round. An association that outlived its round would attach an answer to the wrong comment, which is worse than not offering the action.

It produces a draft, not a posted reply. The words are the agent''s; publishing under the user''s name is the user''s call. It lands in the same pool as every other pending reply — editable, rejectable, published with the review batch.

The prompt says what to do with the comment, not just what it says. Without that instruction a model tends to paraphrase the comment back instead of checking it.

Scope

Both comment surfaces get the reference button, identically — toggle to release, chip with a clear button, released on send, cleared on PR switch. DraftZone does not: a draft is a comment nobody else has written yet, so there is no claim to investigate. That boundary is deliberate rather than an oversight of the comment-surface parity rule.

The glyph is the existing ShareIcon rather than something agent-flavoured, because that is already what "reference" looks like in this app (the finding reference button) — one gesture should not have two icons. Thanks for catching that; my first pass used a robot icon, which drew the target where the established convention draws the action.

Verification

lint / typecheck / test / build pass.

Two visual defects were found by running it, not by the gate — both mine, both fixed here, and worth stating because they show what the gate does not cover:

• I created an empty styles/features/chat.scss while probing a file, which shadowed the features/chat/ style directory that @use ''./styles/features/chat'' resolves to. Every ChatPane style vanished — and the build passed, because an empty stylesheet is not an error. Removed, artifact rebuilt.
• The reference button sized itself to its glyph while the text buttons beside it size to a font-size line box, so it stood taller than its row. Both surfaces now take the same padding and font-size, and the svg is display:block so it does not add descender space.

Beyond those, the interaction has not been exercised end to end against a live agent run — worth one pass to confirm the answer''s use as reply produces a draft anchored to the right comment.

🤖 Generated with Claude Code