diff --git a/apps/web/src/components/pullRequest/PullRequestResolveThreadButton.tsx b/apps/web/src/components/pullRequest/PullRequestResolveThreadButton.tsx
new file mode 100644
index 000000000000..b22a4b870269
--- /dev/null
+++ b/apps/web/src/components/pullRequest/PullRequestResolveThreadButton.tsx
@@ -0,0 +1,96 @@
+import type {
+  EnvironmentId,
+  PullRequestDetailView,
+  PullRequestRef,
+  PullRequestReviewThread,
+} from "@t3tools/contracts";
+import { useState } from "react";
+
+import { useAtomCommand } from "~/state/use-atom-command";
+import { pullRequestEnvironment } from "~/state/pullRequests";
+
+import { Button } from "../ui/button";
+import { toastManager } from "../ui/toast";
+import { canResolvePullRequestThread } from "./pullRequestEditing.logic";
+
+/**
+ * Resolve or unresolve a review thread from a conversation entry rather than from its line in the
+ * Code tab. Callers render it on the thread's first comment only, so a thread with five replies
+ * offers one control, not five. Renders nothing where the host or this account cannot resolve the
+ * thread.
+ */
+export function PullRequestResolveThreadButton({
+  environmentId,
+  reference,
+  detail,
+  thread,
+  className,
+  onRefresh,
+}: {
+  environmentId: EnvironmentId;
+  reference: PullRequestRef;
+  detail: PullRequestDetailView;
+  thread: PullRequestReviewThread;
+  className?: string | undefined;
+  onRefresh: () => void;
+}) {
+  // The state asked for, held until the thread shows it so the button stays disabled through the
+  // refetch instead of re-enabling on the old label. `sent` is the thread as it was when the update
+  // succeeded: any refreshed copy also ends the wait, so a refetch that still reports the old
+  // state cannot leave the button disabled.
+  const [requested, setRequested] = useState<{
+    readonly resolved: boolean;
+    readonly sent: PullRequestReviewThread | null;
+  } | null>(null);
+  if (
+    requested !== null &&
+    (thread.isResolved === requested.resolved ||
+      (requested.sent !== null && thread !== requested.sent))
+  ) {
+    setRequested(null);
+  }
+  const pending = requested !== null;
+  const setThreadResolution = useAtomCommand(pullRequestEnvironment.setThreadResolution, {
+    reportFailure: false,
+  });
+  if (!detail.capabilities.review.resolve || !canResolvePullRequestThread(detail, thread))
+    return null;
+
+  const toggle = async () => {
+    if (pending) return;
+    const resolved = !thread.isResolved;
+    setRequested({ resolved, sent: null });
+    const result = await setThreadResolution({
+      environmentId,
+      input: { ...reference, threadId: thread.id, resolved },
+    });
+    if (result._tag === "Failure") {
+      setRequested(null);
+      toastManager.add({ type: "error", title: "The conversation could not be updated" });
+      return;
+    }
+    setRequested({ resolved, sent: thread });
+    onRefresh();
+  };
+
+  return (
+    <Button
+      size="xs"
+      variant="ghost"
+      className={className}
+      disabled={pending}
+      onClick={() => void toggle()}
+    >
+      {thread.isResolved ? "Unresolve" : "Resolve"}
+    </Button>
+  );
+}
+
+/** The thread a comment opens, or null for replies and for remarks on no thread at all. */
+export function pullRequestThreadOpenedBy(
+  threadByCommentId: ReadonlyMap<string, PullRequestReviewThread>,
+  commentId: string,
+): PullRequestReviewThread | null {
+  const thread = threadByCommentId.get(commentId);
+  return thread?.comments[0]?.id === commentId ? thread : null;
+}
diff --git a/apps/web/src/components/pullRequest/PullRequestSummaryTab.tsx b/apps/web/src/components/pullRequest/PullRequestSummaryTab.tsx
index bfda1209f9cb..15b22ee37d7d 100644
--- a/apps/web/src/components/pullRequest/PullRequestSummaryTab.tsx
+++ b/apps/web/src/components/pullRequest/PullRequestSummaryTab.tsx
@@ -68,6 +68,10 @@ import { PullRequestMarkdown } from "./PullRequestMarkdown";
 import { PullRequestCommentBody } from "./PullRequestCommentBody";
 import { PullRequestMarkdownEditor } from "./PullRequestMarkdownEditor";
 import { PullRequestReactionBar } from "./PullRequestReactions";
+import {
+  PullRequestResolveThreadButton,
+  pullRequestThreadOpenedBy,
+} from "./PullRequestResolveThreadButton";
 import { PullRequestConversationGhost } from "./PullRequestGhosts";
 import { sectionCollapseAnchorScrollTop } from "./pullRequestSummaryScroll.logic";
 
@@ -207,6 +211,7 @@ function CollapsedComment({
   label,
   body,
   reactionBar,
+  resolveButton,
   detail,
   thread,
 }: {
@@ -216,6 +221,7 @@ function CollapsedComment({
   /** Null where the remark is nothing but its verdict, which a dismissal usually is. */
   body: string | null;
   reactionBar: ReactNode;
+  resolveButton: ReactNode;
   detail: PullRequestDetailView;
   thread: PullRequestReviewThread | undefined;
 }) {
@@ -237,6 +243,7 @@ function CollapsedComment({
                 className={cn("size-3.5 transition-transform", open && "rotate-180")}
               />
             </CollapsibleTrigger>
+            {resolveButton}
             {reactionBar}
           </div>
           <CommentLocation comment={comment} thread={thread} />
@@ -562,6 +569,7 @@ export function PullRequestSummaryTab({
 
   const renderComment = (comment: PullRequestComment) => {
     const thread = threadByCommentId.get(comment.id);
+    const openedThread = pullRequestThreadOpenedBy(threadByCommentId, comment.id);
     const body = visibleBody(comment.body);
     if (isFinished(comment)) {
       return (
@@ -573,6 +581,18 @@ export function PullRequestSummaryTab({
           thread={thread}
           label={thread?.isResolved ? "Resolved" : "Review dismissed"}
           body={body}
+          resolveButton={
+            openedThread ? (
+              <PullRequestResolveThreadButton
+                environmentId={environmentId}
+                reference={reference}
+                detail={detail}
+                thread={openedThread}
+                className="shrink-0"
+                onRefresh={onRefresh}
+              />
+            ) : null
+          }
           reactionBar={
             <PullRequestReactionBar
               className="ml-auto justify-end"
@@ -640,6 +660,16 @@ export function PullRequestSummaryTab({
               {pendingFinding === pullRequestFindingKey(finding) ? "Preparing..." : fixFindingLabel}
             </Button>
           ) : null}
+          {openedThread ? (
+            <PullRequestResolveThreadButton
+              environmentId={environmentId}
+              reference={reference}
+              detail={detail}
+              thread={openedThread}
+              className="-mt-1 shrink-0"
+              onRefresh={onRefresh}
+            />
+          ) : null}
           {reactionBar}
         </div>
         <div className="px-3">
diff --git a/apps/web/src/components/pullRequest/PullRequestTimelineTab.tsx b/apps/web/src/components/pullRequest/PullRequestTimelineTab.tsx
index 69421fefbbce..43722a3c60f9 100644
--- a/apps/web/src/components/pullRequest/PullRequestTimelineTab.tsx
+++ b/apps/web/src/components/pullRequest/PullRequestTimelineTab.tsx
@@ -38,6 +38,10 @@ import {
 import { canEditPullRequestComment } from "./pullRequestEditing.logic";
 import { PullRequestMarkdown } from "./PullRequestMarkdown";
 import { PullRequestMarkdownEditor } from "./PullRequestMarkdownEditor";
+import {
+  PullRequestResolveThreadButton,
+  pullRequestThreadOpenedBy,
+} from "./PullRequestResolveThreadButton";
 import { PullRequestReactionBar } from "./PullRequestReactions";
 import {
   PullRequestActorAvatar,
@@ -177,6 +181,7 @@ function OpenOnHostButton({ url, onOpen }: { url: string | null; onOpen: (url: s
 function ConversationCard({
   event,
   editable,
+  resolveButton,
   cwd,
   onOpen,
   reactions,
@@ -184,6 +189,7 @@ function ConversationCard({
   event: PullRequestTimelineEvent;
   /** The remark behind this entry, only where this reader may rewrite it. */
   editable: PullRequestComment | null;
+  resolveButton: ReactNode;
   cwd: string;
   onOpen: (url: string) => void;
   reactions: ReactionSurface;
@@ -239,6 +245,7 @@ function ConversationCard({
               onClick={() => setEditing(true)}
             />
           ) : null}
+          {resolveButton}
           {reactions.canReact || event.reactions.length > 0 ? (
             <PullRequestReactionBar
               className="ml-auto justify-end"
@@ -293,12 +300,14 @@ function uniqueConversationActors(events: ReadonlyArray<PullRequestTimelineEvent
 function ConversationGroup({
   events,
   editable,
+  renderResolveButton,
   cwd,
   onOpen,
   reactions,
 }: {
   events: ReadonlyArray<PullRequestTimelineEvent>;
   editable: ReadonlyMap<string, PullRequestComment>;
+  renderResolveButton: (commentId: string) => ReactNode;
   cwd: string;
   onOpen: (url: string) => void;
   reactions: ReactionSurface;
@@ -352,6 +361,7 @@ function ConversationGroup({
                     key={`${reactions.reference.projectId}#${reactions.reference.number}:${event.id}`}
                     event={event}
                     editable={editable.get(event.id) ?? null}
+                    resolveButton={renderResolveButton(event.id)}
                     cwd={cwd}
                     onOpen={onOpen}
                     reactions={reactions}
@@ -570,6 +580,24 @@ export function PullRequestTimelineTab({
       .filter((comment) => canEditPullRequestComment(detail, comment))
       .map((comment) => [comment.id, comment] as const),
   );
+  const threadByCommentId = new Map(
+    detail.reviewThreads.flatMap((thread) =>
+      thread.comments.map((comment) => [comment.id, thread] as const),
+    ),
+  );
+  const renderResolveButton = (commentId: string) => {
+    const thread = pullRequestThreadOpenedBy(threadByCommentId, commentId);
+    return thread ? (
+      <PullRequestResolveThreadButton
+        environmentId={environmentId}
+        reference={reference}
+        detail={detail}
+        thread={thread}
+        className="-mt-1"
+        onRefresh={onRefresh}
+      />
+    ) : null;
+  };
   const orderedEvents = order === "newest" ? events : events.toReversed();
   const rows = groupPullRequestTimelineConversations(orderedEvents);
   const openOnHost = (url: string) => {
@@ -588,6 +616,7 @@ export function PullRequestTimelineTab({
                   key={`comments:${row.events[0]?.id ?? "empty"}`}
                   events={row.events}
                   editable={editable}
+                  renderResolveButton={renderResolveButton}
                   cwd={detail.workspaceRoot}
                   onOpen={openOnHost}
                   reactions={reactions}