[Feature]: Linkify bare #N issue references in chat and show a hover card preview

[Xentox-Phil]

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

Agents refer to issues by bare number all the time, for example "Remove = soft delete (removed_at), with lineItem.restore as its inverse, built in #31? I recommend yes". The agent knows what #31 is because it's in its context. I don't. #31 renders as plain text: no link, no title, nothing to hover.

So every time I have to stop, open GitHub, find #31, then come back, or ask the agent "what was #31 again?". It happens many times per session, especially in decision questions where the issue number is the context I need to answer.

Proposed solution

• Linkify bare references in assistant messages: #N resolves against the thread's project repo, and owner/repo#N against that repo. Render them as the existing issue/PR chips ([Feature]: Show PRs and issues differently in chat link chips #25894).
• Hover card on those chips, and on full issue/PR URL chips, fetched lazily on hover and cached: title, type (issue/PR), state (open/closed/merged), labels, assignee, the first 2–3 lines of the body. GitHub's own hovercard is the model.
• If the number doesn't exist in the repo, leave it as plain text.

Smallest useful scope

Bare #N → chip for the project's GitHub repo, with a hover card showing title + state. Labels, body excerpt and cross-repo references can follow.

Related

• [Feature]: Show PRs and issues differently in chat link chips #25894 (issue/PR chip icons, full URLs only)
• feat(issues): link issues to threads and expose issue tools to agents #19270 (thread issue snapshots: key, title, state; could back the card)
• Feature: Add an Issues panel alongside Pull Requests #11067 (Issues panel, full detail view)

[Xentox-Phil]

here the 31 should be a chip.