Release 0.2.1: PRView Rules-of-Hooks fix (React #310 blank page)

PRView.jsx declared its threadsByKind useMemo after the early-return
guard for the loading state. First mount: pr is null, early return
fires, 14 hooks called. Second render: pr populated, execution
reaches the useMemo, 15 hooks — React #310, page goes blank.

Move the useMemo above the early returns and null-safe the
pr?.threads access so the hook count stays stable across renders.

Pre-existing bug in the post-Contribute-rewrite PR view; surfaced
in production by 0.2.0's graduation merge race fix enabling the
workflow that opens this code path. Patch per §20.2 — no operator
action required beyond rebuilding the frontend and restarting.

CHANGELOG.md

@@ -23,6 +23,28 @@ skip versions are the composition of each intervening adjacent
 release's steps in order — no A-to-B path is pre-computed beyond
 that.
 
+## 0.2.1 — 2026-05-26
+
+**Patch — no operator action required.** Rebuild the frontend and
+restart per the routine deploy steps; no `.env` changes, no schema
+changes, no behavior changes a deployment would notice in steady
+state.
+
+### Fixed
+
+- **PR view blank page (React #310).** `frontend/src/components/PRView.jsx`
+  declared its `threadsByKind` `useMemo` *after* the early-return
+  guard for the loading state (`if (!pr) return …`). On first mount
+  `pr` was null so the early return fired and 14 hooks were called;
+  on the second render `pr` was populated and execution reached the
+  `useMemo`, calling 15 hooks — violating the Rules of Hooks and
+  unmounting the page subtree (blank screen). The `useMemo` is now
+  declared above the early returns with optional-chaining on `pr`,
+  keeping the hook count stable between the loading and loaded
+  renders. Pre-existing bug in the post-Contribute-rewrite PR view;
+  surfaced in production by 0.2.0's graduation merge race fix
+  enabling the workflow that opens this code path.
+
 ## 0.2.0 — 2026-05-26
 
 **Breaking config change.** The frontend now requires

VERSION

@@ -1 +1 @@
-0.2.0
+0.2.1

frontend/package-lock.json

@@ -1,12 +1,12 @@
 {
   "name": "rfc-app-frontend",
-  "version": "0.1.0",
+  "version": "0.2.1",
   "lockfileVersion": 3,
   "requires": true,
   "packages": {
     "": {
       "name": "rfc-app-frontend",
-      "version": "0.1.0",
+      "version": "0.2.1",
       "dependencies": {
         "@codemirror/commands": "^6.10.3",
         "@codemirror/lang-markdown": "^6.5.0",

frontend/package.json

@@ -1,7 +1,7 @@
 {
   "name": "rfc-app-frontend",
   "private": true,
-  "version": "0.2.0",
+  "version": "0.2.1",
   "type": "module",
   "scripts": {
     "dev": "vite",

frontend/src/components/PRView.jsx

@@ -143,6 +143,19 @@ export default function PRView({ viewer }) {
     }
   }, [slug, prNumber, reviewText, reviewDraft, refresh])
 
+  // §10.6: split messages by thread kind for the visual distinction
+  // §10.4 requires. Within each kind, sort by id for chronological
+  // order. Declared above the early returns below so the hook count
+  // stays stable between the loading render (pr == null) and the
+  // loaded render (Rules of Hooks — React #310 otherwise).
+  const threadsByKind = useMemo(() => {
+    const out = { chat: [], review: [], flag: [] }
+    for (const t of pr?.threads || []) {
+      out[t.thread_kind]?.push(t)
+    }
+    return out
+  }, [pr?.threads])
+
   // ── render ─────────────────────────────────────────────────────
   if (error) return <article className="entry-view"><p>Error: {error}</p></article>
   if (!pr) return <article className="entry-view">Loading PR…</article>
@@ -154,17 +167,6 @@ export default function PRView({ viewer }) {
   const supersededBy = pr.superseded_by_pr_number
   const supersedes = pr.supersedes_pr_number
 
-  // §10.6: split messages by thread kind for the visual distinction
-  // §10.4 requires. Within each kind, sort by id for chronological
-  // order.
-  const threadsByKind = useMemo(() => {
-    const out = { chat: [], review: [], flag: [] }
-    for (const t of pr.threads || []) {
-      out[t.thread_kind]?.push(t)
-    }
-    return out
-  }, [pr.threads])
-
   const seenSha = pr.seen?.last_seen_commit_sha
   const seenMsgId = pr.seen?.last_seen_message_id || 0