diff --git a/src/components/Changes.svelte b/src/components/Changes.svelte
index 585f9faff..91199e011 100644
--- a/src/components/Changes.svelte
+++ b/src/components/Changes.svelte
@@ -15,7 +15,12 @@
     stepIndex,
   } from "@app/lib/commentNavigation";
   import { diffOptions } from "@app/lib/diffOptions.svelte";
-  import { fileDiffPath, fileMetaOf, fullFileLoader } from "@app/lib/diffText";
+  import {
+    checkedPaths,
+    fileDiffPath,
+    fileMetaOf,
+    fullFileLoader,
+  } from "@app/lib/diffText";
   import { draftReviewStorage } from "@app/lib/draftReviewStorage";
   import {
     cachedDiffStats,
@@ -207,28 +212,18 @@
   const fileMeta = $derived(fileMetaOf(diffFiles));
 
   const reviewedPaths = $derived.by(() => {
-    if (!draftReviewId) return undefined;
-    // eslint-disable-next-line svelte/prefer-svelte-reactivity -- rebuilt fresh each derivation
-    const paths = new Set<string>();
-    for (const file of diffFiles) {
-      const path = fileDiffPath(file);
-      if (draftReviewStorage.isFileChecked(draftReviewId, path)) {
-        paths.add(path);
-      }
-    }
-    return paths;
+    const id = draftReviewId;
+    if (!id) return undefined;
+    return checkedPaths(diffFiles, path =>
+      draftReviewStorage.isFileChecked(id, path),
+    );
   });
 
   // Lockfiles and generated manifests are noise in a review, and a file already
   // marked reviewed has been dealt with, so both start collapsed.
-  const collapsedPaths = $derived.by(() => {
-    // eslint-disable-next-line svelte/prefer-svelte-reactivity -- rebuilt fresh each derivation
-    const paths = new Set(fileMeta.ignored);
-    for (const path of reviewedPaths ?? []) {
-      paths.add(path);
-    }
-    return paths;
-  });
+  const collapsedPaths = $derived(
+    new Set([...fileMeta.ignored, ...(reviewedPaths ?? [])]),
+  );
 
   const commentCounts = $derived.by(() => {
     const comments = diffCodeComments;
diff --git a/src/lib/diffText.ts b/src/lib/diffText.ts
index 2ea34dc5c..69910391e 100644
--- a/src/lib/diffText.ts
+++ b/src/lib/diffText.ts
@@ -130,3 +130,23 @@ export function fullFileLoader(
     return { oldContents, newContents };
   };
 }
+
+/// How many of the diff's files a reviewer has checked off. Checks left over
+/// from files the diff no longer has don't count.
+export function checkedFileProgress(
+  files: FileDiff[],
+  checkedFiles: string[],
+): { filesChecked: number; filesTotal: number } {
+  const paths = new Set(files.map(fileDiffPath));
+  return {
+    filesChecked: checkedFiles.filter(path => paths.has(path)).length,
+    filesTotal: files.length,
+  };
+}
+
+export function checkedPaths(
+  files: FileDiff[],
+  isChecked: (path: string) => boolean,
+): Set<string> {
+  return new Set(files.map(fileDiffPath).filter(isChecked));
+}
diff --git a/src/views/repo/Patch.svelte b/src/views/repo/Patch.svelte
index b5449b9f4..561f9e407 100644
--- a/src/views/repo/Patch.svelte
+++ b/src/views/repo/Patch.svelte
@@ -12,10 +12,12 @@
   import type { Commit } from "@bindings/repo/Commit";
   import type { RepoInfo } from "@bindings/repo/RepoInfo";
 
+  import countBy from "lodash/countBy";
   import mapValues from "lodash/mapValues";
   import { SvelteSet } from "svelte/reactivity";
 
   import { commentSourcesOf } from "@app/lib/commentSources";
+  import { checkedFileProgress } from "@app/lib/diffText";
   import { draftReviewStorage } from "@app/lib/draftReviewStorage";
   import { nodeRunning } from "@app/lib/events";
   import {
@@ -329,16 +331,8 @@
           status: undefined,
         }),
       ]);
-      const patchCounts: Record<string, number> = {};
-      for (const p of patches.content) {
-        patchCounts[p.author.did] = (patchCounts[p.author.did] ?? 0) + 1;
-      }
-      const issueCounts: Record<string, number> = {};
-      for (const i of issues) {
-        issueCounts[i.author.did] = (issueCounts[i.author.did] ?? 0) + 1;
-      }
-      patchesAuthoredByDid = patchCounts;
-      issuesAuthoredByDid = issueCounts;
+      patchesAuthoredByDid = countBy(patches.content, p => p.author.did);
+      issuesAuthoredByDid = countBy(issues, i => i.author.did);
       lastActivityRid = targetRid;
       activityLoaded = true;
     } catch (error) {
@@ -554,18 +548,7 @@
       head: rev.head,
     }).then(diff => {
       if (cancelled) return;
-      const filePaths = new Set(
-        diff.files.map(f =>
-          f.status === "moved" || f.status === "copied" ? f.newPath : f.path,
-        ),
-      );
-      const filesChecked = draft.checkedFiles.filter(p =>
-        filePaths.has(p),
-      ).length;
-      fileProgress = {
-        filesChecked,
-        filesTotal: diff.files.length,
-      };
+      fileProgress = checkedFileProgress(diff.files, draft.checkedFiles);
     });
     return () => {
       cancelled = true;