diff --git a/apps/web/src/appSettings.ts b/apps/web/src/appSettings.ts
index 4dbd29e66..fe6eb6957 100644
--- a/apps/web/src/appSettings.ts
+++ b/apps/web/src/appSettings.ts
@@ -88,6 +88,7 @@ export const AppSettingsSchema = Schema.Struct({
   sidebarAccentProjectNames: Schema.Boolean.pipe(withDefaults(() => true)),
   sidebarAccentColorOverride: Schema.optional(Schema.String.check(Schema.isMaxLength(64))),
   sidebarAccentBgColorOverride: Schema.optional(Schema.String.check(Schema.isMaxLength(64))),
+  showReasoningContent: Schema.Boolean.pipe(withDefaults(() => false)),
   showStitchBorder: Schema.Boolean.pipe(withDefaults(() => true)),
   customCodexModels: Schema.Array(Schema.String).pipe(withDefaults(() => [])),
   customClaudeModels: Schema.Array(Schema.String).pipe(withDefaults(() => [])),
diff --git a/apps/web/src/components/ChatView.tsx b/apps/web/src/components/ChatView.tsx
index 23418dc3b..bd52ad92c 100644
--- a/apps/web/src/components/ChatView.tsx
+++ b/apps/web/src/components/ChatView.tsx
@@ -380,6 +380,7 @@ export default function ChatView({ threadId }: ChatViewProps) {
   const { settings } = useAppSettings();
   const setStickyComposerModel = useComposerDraftStore((store) => store.setStickyModel);
   const timestampFormat = settings.timestampFormat;
+  const showReasoningContent = settings.showReasoningContent;
   const navigate = useNavigate();
   const activeProjectId = threads.find((t) => t.id === threadId)?.projectId ?? null;
   const previewOpen = usePreviewStateStore((state) =>
@@ -4741,6 +4742,7 @@ export default function ChatView({ threadId }: ChatViewProps) {
                   onImageExpand={onExpandTimelineImage}
                   markdownCwd={gitCwd ?? undefined}
                   resolvedTheme={resolvedTheme}
+                  showReasoningContent={showReasoningContent}
                   timestampFormat={timestampFormat}
                   workspaceRoot={activeProject?.cwd ?? undefined}
                   shortcutGuides={chatShortcutGuides}
diff --git a/apps/web/src/components/chat/MessagesTimeline.test.tsx b/apps/web/src/components/chat/MessagesTimeline.test.tsx
index 4d8125479..7d5627ca9 100644
--- a/apps/web/src/components/chat/MessagesTimeline.test.tsx
+++ b/apps/web/src/components/chat/MessagesTimeline.test.tsx
@@ -99,6 +99,7 @@ describe("MessagesTimeline", () => {
         onImageExpand={() => {}}
         markdownCwd={undefined}
         resolvedTheme="light"
+        showReasoningContent={false}
         timestampFormat="locale"
         workspaceRoot={undefined}
         onRemoveQueuedMessage={() => {}}
@@ -146,6 +147,7 @@ describe("MessagesTimeline", () => {
         onImageExpand={() => {}}
         markdownCwd={undefined}
         resolvedTheme="light"
+        showReasoningContent={false}
         timestampFormat="locale"
         workspaceRoot={undefined}
         onRemoveQueuedMessage={() => {}}
@@ -180,6 +182,7 @@ describe("MessagesTimeline", () => {
         onImageExpand={() => {}}
         markdownCwd={undefined}
         resolvedTheme="light"
+        showReasoningContent={false}
         timestampFormat="locale"
         workspaceRoot={undefined}
         onRemoveQueuedMessage={() => {}}
diff --git a/apps/web/src/components/chat/MessagesTimeline.tsx b/apps/web/src/components/chat/MessagesTimeline.tsx
index 3c543d486..25adf1f1a 100644
--- a/apps/web/src/components/chat/MessagesTimeline.tsx
+++ b/apps/web/src/components/chat/MessagesTimeline.tsx
@@ -85,6 +85,7 @@ interface MessagesTimelineProps {
   onImageExpand: (preview: ExpandedImagePreview) => void;
   markdownCwd: string | undefined;
   resolvedTheme: "light" | "dark";
+  showReasoningContent: boolean;
   timestampFormat: TimestampFormat;
   workspaceRoot: string | undefined;
   onRemoveQueuedMessage: (messageId: MessageId) => void;
@@ -111,6 +112,7 @@ export const MessagesTimeline = memo(function MessagesTimeline({
   onImageExpand,
   markdownCwd,
   resolvedTheme,
+  showReasoningContent,
   timestampFormat,
   workspaceRoot,
   onRemoveQueuedMessage,
@@ -372,6 +374,7 @@ export const MessagesTimeline = memo(function MessagesTimeline({
                       key={`work-row:${subGroup.entries[0]!.id}`}
                       workEntry={subGroup.entries[0]!}
                       resolvedTheme={resolvedTheme}
+                      showReasoningContent={showReasoningContent}
                     />
                   ) : (
                     <CollapsedWorkEntryGroup
@@ -379,6 +382,7 @@ export const MessagesTimeline = memo(function MessagesTimeline({
                       heading={subGroup.heading}
                       entries={subGroup.entries}
                       resolvedTheme={resolvedTheme}
+                      showReasoningContent={showReasoningContent}
                     />
                   ),
                 )}
@@ -1072,8 +1076,9 @@ function groupConsecutiveWorkEntries(entries: TimelineWorkEntry[]): ConsecutiveW
 const SimpleWorkEntryRow = memo(function SimpleWorkEntryRow(props: {
   workEntry: TimelineWorkEntry;
   resolvedTheme: "light" | "dark";
+  showReasoningContent: boolean;
 }) {
-  const { workEntry, resolvedTheme } = props;
+  const { workEntry, resolvedTheme, showReasoningContent } = props;
   const iconConfig = workToneIcon(workEntry.tone);
   const EntryIcon = workEntryIcon(workEntry);
   const heading = toolWorkEntryHeading(workEntry);
@@ -1081,6 +1086,8 @@ const SimpleWorkEntryRow = memo(function SimpleWorkEntryRow(props: {
   const hasChangedFiles = (workEntry.changedFiles?.length ?? 0) > 0;
   const previewIsChangedFiles = hasChangedFiles && !workEntry.command && !workEntry.detail;
   const hasDiffData = workEntry.diffData != null && workEntry.itemType === "file_change";
+  const isReasoningWithDetail =
+    showReasoningContent && workEntry.label === "Reasoning update" && !!workEntry.detail;
 
   return (
     <div className="rounded-lg px-1 py-1">
@@ -1105,6 +1112,13 @@ const SimpleWorkEntryRow = memo(function SimpleWorkEntryRow(props: {
           </p>
         </div>
       </div>
+      {isReasoningWithDetail && (
+        <div className="mt-1 pl-7">
+          <p className="whitespace-pre-wrap text-[10px] leading-4 text-muted-foreground/60">
+            {workEntry.detail}
+          </p>
+        </div>
+      )}
       {hasDiffData ? (
         <div className="mt-1.5 pl-6">
           <InlineDiffBlock diffData={workEntry.diffData!} resolvedTheme={resolvedTheme} />
@@ -1140,8 +1154,9 @@ const CollapsedWorkEntryGroup = memo(function CollapsedWorkEntryGroup(props: {
   heading: string;
   entries: TimelineWorkEntry[];
   resolvedTheme: "light" | "dark";
+  showReasoningContent: boolean;
 }) {
-  const { heading, entries, resolvedTheme } = props;
+  const { heading, entries, resolvedTheme, showReasoningContent } = props;
   const [isExpanded, setIsExpanded] = useState(false);
   const firstEntry = entries[0]!;
   const EntryIcon = workEntryIcon(firstEntry);
@@ -1177,10 +1192,17 @@ const CollapsedWorkEntryGroup = memo(function CollapsedWorkEntryGroup(props: {
           {entries.map((entry) => {
             const preview = workEntryPreview(entry);
             const hasDiff = entry.diffData != null && entry.itemType === "file_change";
+            const showReasoningDetail =
+              showReasoningContent && entry.label === "Reasoning update" && !!entry.detail;
             return (
               <div key={`subentry:${entry.id}`}>
-                <p className="truncate py-0.5 text-[10px] leading-4 text-muted-foreground/55">
-                  {preview ?? heading}
+                <p
+                  className={cn(
+                    "py-0.5 text-[10px] leading-4 text-muted-foreground/55",
+                    !showReasoningDetail && "truncate",
+                  )}
+                >
+                  {showReasoningDetail ? entry.detail : (preview ?? heading)}
                 </p>
                 {hasDiff && (
                   <div className="mt-1">
diff --git a/apps/web/src/routes/_chat.settings.tsx b/apps/web/src/routes/_chat.settings.tsx
index 8662b5e44..190c0bb55 100644
--- a/apps/web/src/routes/_chat.settings.tsx
+++ b/apps/web/src/routes/_chat.settings.tsx
@@ -422,6 +422,9 @@ function SettingsRouteView() {
     ...(settings.enableAssistantStreaming !== defaults.enableAssistantStreaming
       ? ["Assistant output"]
       : []),
+    ...(settings.showReasoningContent !== defaults.showReasoningContent
+      ? ["Reasoning content"]
+      : []),
     ...(settings.showAuthFailuresAsErrors !== defaults.showAuthFailuresAsErrors
       ? ["Auth failure errors"]
       : []),
@@ -1131,6 +1134,34 @@ function SettingsRouteView() {
                 }
               />
 
+              <SettingsRow
+                title="Reasoning content"
+                description="Show reasoning/thinking content in the work log instead of just showing 'Reasoning update'."
+                resetAction={
+                  settings.showReasoningContent !== defaults.showReasoningContent ? (
+                    <SettingResetButton
+                      label="reasoning content"
+                      onClick={() =>
+                        updateSettings({
+                          showReasoningContent: defaults.showReasoningContent,
+                        })
+                      }
+                    />
+                  ) : null
+                }
+                control={
+                  <Switch
+                    checked={settings.showReasoningContent}
+                    onCheckedChange={(checked) =>
+                      updateSettings({
+                        showReasoningContent: Boolean(checked),
+                      })
+                    }
+                    aria-label="Show reasoning content in work log"
+                  />
+                }
+              />
+
               <SettingsRow
                 title="Auth failure errors"
                 description="Show provider authentication failures in the thread error banner. Turn this off to keep login issues out of the main error state."