fix(code-review): show PR comment counts on files

packages/ui/src/features/code-review/components/PatchedFileDiff.test.tsx

@@ -0,0 +1,82 @@
+import type { FileDiffMetadata } from "@pierre/diffs";
+import type { PrCommentThread } from "@posthog/core/code-review/types";
+import type { ChangedFile } from "@posthog/shared/domain-types";
+import { render, screen } from "@testing-library/react";
+import type { ReactNode } from "react";
+import { describe, expect, it, vi } from "vitest";
+
+vi.mock("../../../primitives/FileIcon", () => ({
+  FileIcon: () => <span data-testid="file-icon" />,
+}));
+
+vi.mock("./InteractiveFileDiff", () => ({
+  InteractiveFileDiff: ({
+    fileDiff,
+    renderCustomHeader,
+  }: {
+    fileDiff: FileDiffMetadata;
+    renderCustomHeader: (fileDiff: FileDiffMetadata) => ReactNode;
+  }) => renderCustomHeader(fileDiff),
+}));
+
+import { PatchedFileDiff } from "./PatchedFileDiff";
+
+const patch = `diff --git a/src/reviewed.ts b/src/reviewed.ts
+index 1111111..2222222 100644
+--- a/src/reviewed.ts
++++ b/src/reviewed.ts
+@@ -1 +1 @@
+-before
++after`;
+
+describe.each([
+  [
+    "regular",
+    {
+      path: "src/reviewed.ts",
+      originalPath: "src/original.ts",
+      patch,
+    },
+  ],
+  ["binary", { path: "assets/reviewed.png", patch: null }],
+  ["unavailable", { path: "src/unavailable.ts", patch: null }],
+] as const)("PatchedFileDiff %s header", (_kind, fileInput) => {
+  it("renders metadata before line change stats", () => {
+    const file = {
+      ...fileInput,
+      linesAdded: 2,
+      linesRemoved: 1,
+    } as ChangedFile;
+    const threadPath = file.originalPath ?? file.path;
+    const commentThreads = new Map<number, PrCommentThread>([
+      [
+        1,
+        {
+          rootId: 1,
+          nodeId: "thread-1",
+          isResolved: false,
+          filePath: threadPath,
+          comments: [{ id: 1 }, { id: 2 }] as PrCommentThread["comments"],
+        },
+      ],
+    ]);
+
+    render(
+      <PatchedFileDiff
+        file={file}
+        taskId="task"
+        options={{}}
+        collapsed
+        onToggle={() => {}}
+        commentThreads={commentThreads}
+      />,
+    );
+
+    const header = screen.getByRole("button");
+    const text = header.textContent ?? "";
+    const additions = _kind === "regular" ? "+1" : "+2";
+
+    expect(screen.getByTitle("2 comments")).toBeInTheDocument();
+    expect(text.indexOf("2 comments")).toBeLessThan(text.indexOf(additions));
+  });
+});

packages/ui/src/features/code-review/components/PatchedFileDiff.tsx

@@ -49,6 +49,7 @@ export function PatchedFileDiff({
     }
     return null;
   }, [fileDiff, fallback, file.path]);
+  const commentCount = countPrCommentsForFile(commentThreads, file);
 
   // Branch/PR diffs have no reliable local working-tree file to preview (the
   // checkout may be on a different ref, and GitHub omits binary patches), so
@@ -63,6 +64,7 @@ export function PatchedFileDiff({
         collapsed={collapsed}
         onToggle={onToggle}
         externalUrl={externalUrl}
+        commentCount={commentCount}
         headerTrailing={headerTrailing}
       />
     );
@@ -78,6 +80,7 @@ export function PatchedFileDiff({
         collapsed={collapsed}
         onToggle={onToggle}
         externalUrl={externalUrl}
+        commentCount={commentCount}
         headerTrailing={headerTrailing}
       />
     );
@@ -95,9 +98,26 @@ export function PatchedFileDiff({
           fileDiff={fd}
           collapsed={collapsed}
           onToggle={onToggle}
+          commentCount={commentCount}
           trailing={headerTrailing}
         />
       )}
     />
   );
 }
+
+function countPrCommentsForFile(
+  threads: Map<number, PrCommentThread> | undefined,
+  file: Pick<ChangedFile, "path" | "originalPath">,
+): number {
+  let count = 0;
+  for (const thread of threads?.values() ?? []) {
+    if (
+      thread.filePath === file.path ||
+      (file.originalPath != null && thread.filePath === file.originalPath)
+    ) {
+      count += thread.comments.length;
+    }
+  }
+  return count;
+}

packages/ui/src/features/code-review/reviewShellParts.test.tsx

@@ -36,12 +36,13 @@ function findSpan(
   return found;
 }
 
-function renderHeader(path: string) {
+function renderHeader(path: string, commentCount?: number) {
   const diff = render(
     <DiffFileHeader
       fileDiff={makeFileDiff(path)}
       collapsed={false}
       onToggle={() => {}}
+      commentCount={commentCount}
     />,
   );
   const deferred = render(
@@ -52,6 +53,7 @@ function renderHeader(path: string) {
       reason="line-limit"
       collapsed={false}
       onToggle={() => {}}
+      commentCount={commentCount}
     />,
   );
   return { diff, deferred };
@@ -96,4 +98,12 @@ describe.each([
     expect(dirSpan.parentElement).toBe(fileSpan.parentElement);
     expect(dirSpan.parentElement?.classList.contains("flex")).toBe(true);
   });
+
+  it("renders metadata before line changes", () => {
+    const rendered = renderHeader("src/ReviewShell.tsx", 2)[which];
+    const text = rendered.container.querySelector("button")?.textContent ?? "";
+    const additions = which === "diff" ? "+3" : "+10";
+
+    expect(text.indexOf("2 comments")).toBeLessThan(text.indexOf(additions));
+  });
 });

packages/ui/src/features/code-review/reviewShellParts.tsx

@@ -2,6 +2,7 @@ import {
   ArrowCounterClockwise,
   ArrowSquareOut,
   CaretDown,
+  ChatCircle,
   Minus,
   Plus,
 } from "@phosphor-icons/react";
@@ -13,6 +14,7 @@ import {
   splitFilePath,
   sumHunkStats,
 } from "@posthog/core/code-review/reviewShellGeometry";
+import { Badge } from "@posthog/quill";
 import type { ChangedFile, Task } from "@posthog/shared/domain-types";
 import { type ReactNode, useCallback, useMemo, useState } from "react";
 import { FileIcon } from "../../primitives/FileIcon";
@@ -139,6 +141,7 @@ export function FileHeaderRow({
   deletions,
   collapsed,
   onToggle,
+  commentCount,
   trailing,
 }: {
   dirPath: string;
@@ -147,6 +150,7 @@ export function FileHeaderRow({
   deletions: number;
   collapsed: boolean;
   onToggle: () => void;
+  commentCount?: number;
   trailing?: ReactNode;
 }) {
   return (
@@ -176,6 +180,9 @@ export function FileHeaderRow({
           {dirPath}
         </span>
       </span>
+      {commentCount != null && commentCount > 0 && (
+        <PrCommentCountBadge count={commentCount} />
+      )}
       <span className="font-mono text-[10px]">
         {additions > 0 && (
           <span className="mr-[2px] text-(--green-9)">+{additions}</span>
@@ -210,6 +217,7 @@ export function DiffFileHeader({
   onDiscard,
   onStage,
   staged,
+  commentCount,
   trailing,
 }: {
   fileDiff: FileDiffMetadata;
@@ -219,6 +227,7 @@ export function DiffFileHeader({
   onDiscard?: () => void;
   onStage?: () => void;
   staged?: boolean;
+  commentCount?: number;
   /** Extra controls rendered after the action buttons (e.g. a "Viewed" toggle). */
   trailing?: ReactNode;
 }) {
@@ -237,6 +246,7 @@ export function DiffFileHeader({
       deletions={deletions}
       collapsed={collapsed}
       onToggle={onToggle}
+      commentCount={commentCount}
       trailing={
         (onStage || onDiscard || onOpenFile || trailing) && (
           <span className="ml-auto inline-flex items-center gap-[2px]">
@@ -299,6 +309,7 @@ export function DeferredDiffPlaceholder({
   onToggle,
   onShow,
   externalUrl,
+  commentCount,
   headerTrailing,
 }: {
   filePath: string;
@@ -309,6 +320,7 @@ export function DeferredDiffPlaceholder({
   onToggle: () => void;
   onShow?: () => void;
   externalUrl?: string;
+  commentCount?: number;
   /** Extra controls in the header row (e.g. a "Viewed" toggle). */
   headerTrailing?: ReactNode;
 }) {
@@ -323,6 +335,7 @@ export function DeferredDiffPlaceholder({
         deletions={linesRemoved}
         collapsed={collapsed}
         onToggle={onToggle}
+        commentCount={commentCount}
         trailing={
           headerTrailing && (
             <span className="ml-auto inline-flex items-center">
@@ -369,3 +382,18 @@ export function DeferredDiffPlaceholder({
     </div>
   );
 }
+
+function PrCommentCountBadge({ count }: { count: number }) {
+  const label = `${count} comment${count === 1 ? "" : "s"}`;
+  return (
+    <Badge
+      variant="default"
+      title={label}
+      className="shrink-0 gap-[3px] border-(--gray-7) bg-(--gray-3) text-[11px] text-gray-12 tabular-nums"
+    >
+      <ChatCircle size={12} weight="fill" />
+      {count}
+      <span className="sr-only"> comment{count === 1 ? "" : "s"}</span>
+    </Badge>
+  );
+}

packages/ui/src/features/git-interaction/usePrDetails.ts

@@ -8,18 +8,10 @@ interface UsePrDetailsOptions {
   includeComments?: boolean;
 }
 
-function threadsToMap(threads: PrReviewThread[]): Map<number, PrCommentThread> {
-  const map = new Map<number, PrCommentThread>();
-  for (const thread of threads) {
-    map.set(thread.rootId, {
-      rootId: thread.rootId,
-      nodeId: thread.nodeId,
-      isResolved: thread.isResolved,
-      comments: thread.comments,
-      filePath: thread.filePath,
-    });
-  }
-  return map;
+function mapPrCommentThreads(
+  threads: PrReviewThread[],
+): Map<number, PrCommentThread> {
+  return new Map(threads.map((thread) => [thread.rootId, thread]));
 }
 
 export interface PrStateDetails {
@@ -80,7 +72,7 @@ export function usePrDetails(
   });
 
   const commentThreads = useMemo(
-    () => threadsToMap(commentsQuery.data ?? []),
+    () => mapPrCommentThreads(commentsQuery.data ?? []),
     [commentsQuery.data],
   );