Review a PR directly by URL/number (`hunk diff --pr`)

[benvinegar]

Gap

hunk reviews local git history only. To review an agent-opened PR, you must gh pr checkout first. There's no way to point hunk at a PR.

What competitors do

difit --pr <url> fetches the patch via gh pr diff --patch, and even imports unresolved inline review threads as startup comments (GH Enterprise + token auth supported). lumen has lumen diff --pr 123 plus auto-detection of the current branch's PR.

Why it matters for hunk

hunk's audience reviews PRs authored by agents (Claude Code, Copilot, etc.). 'Review this PR' is the canonical entry point and hunk currently can't serve it without manual checkout. This is the biggest reach gap.

Note vs #460

#460 is the outbound direction (publish accepted notes as a GitHub PR review). This is the inbound direction (open a PR in hunk to review it). They compose well.

Sketch

• hunk diff --pr <url|number> shells to gh pr diff --patch and feeds the patch path.
• Optional: import unresolved review threads as startup notes.
• Keep it forge-agnostic where possible; gh for GitHub first.

Related: #460. Source: competitor gap analysis (difit, lumen).