diff --git a/packages/app/src/i18n/ar.ts b/packages/app/src/i18n/ar.ts
index 81cc92bf6de2..94ea7d55c27f 100644
--- a/packages/app/src/i18n/ar.ts
+++ b/packages/app/src/i18n/ar.ts
@@ -441,6 +441,8 @@ export const dict = {
   "session.files.selectToOpen": "اختر ملفًا لفتحه",
   "session.files.all": "كل الملفات",
   "session.files.binaryContent": "ملف ثنائي (لا يمكن عرض المحتوى)",
+  "session.files.viewPreview": "استعراض",
+  "session.files.viewSource": "مصدر",
   "session.messages.renderEarlier": "عرض الرسائل السابقة",
   "session.messages.loadingEarlier": "جارٍ تحميل الرسائل السابقة...",
   "session.messages.loadEarlier": "تحميل الرسائل السابقة",
diff --git a/packages/app/src/i18n/br.ts b/packages/app/src/i18n/br.ts
index 9ed3a9fc6fc1..7c4ebfd30c68 100644
--- a/packages/app/src/i18n/br.ts
+++ b/packages/app/src/i18n/br.ts
@@ -444,6 +444,8 @@ export const dict = {
   "session.files.selectToOpen": "Selecione um arquivo para abrir",
   "session.files.all": "Todos os arquivos",
   "session.files.binaryContent": "Arquivo binário (conteúdo não pode ser exibido)",
+  "session.files.viewPreview": "Pré-visualização",
+  "session.files.viewSource": "Código-fonte",
   "session.messages.renderEarlier": "Renderizar mensagens anteriores",
   "session.messages.loadingEarlier": "Carregando mensagens anteriores...",
   "session.messages.loadEarlier": "Carregar mensagens anteriores",
diff --git a/packages/app/src/i18n/bs.ts b/packages/app/src/i18n/bs.ts
index 206aae3729da..f460cd93bc23 100644
--- a/packages/app/src/i18n/bs.ts
+++ b/packages/app/src/i18n/bs.ts
@@ -497,6 +497,8 @@ export const dict = {
   "session.files.selectToOpen": "Odaberi datoteku za otvaranje",
   "session.files.all": "Sve datoteke",
   "session.files.binaryContent": "Binarna datoteka (sadržaj se ne može prikazati)",
+  "session.files.viewPreview": "Pregled",
+  "session.files.viewSource": "Izvorni kod",
 
   "session.messages.renderEarlier": "Prikaži ranije poruke",
   "session.messages.loadingEarlier": "Učitavanje ranijih poruka...",
diff --git a/packages/app/src/i18n/da.ts b/packages/app/src/i18n/da.ts
index 6bf67168fb08..f818143740f3 100644
--- a/packages/app/src/i18n/da.ts
+++ b/packages/app/src/i18n/da.ts
@@ -493,6 +493,8 @@ export const dict = {
   "session.files.selectToOpen": "Vælg en fil at åbne",
   "session.files.all": "Alle filer",
   "session.files.binaryContent": "Binær fil (indhold kan ikke vises)",
+  "session.files.viewPreview": "Forhåndsvisning",
+  "session.files.viewSource": "Kilde",
   "session.messages.renderEarlier": "Vis tidligere beskeder",
   "session.messages.loadingEarlier": "Indlæser tidligere beskeder...",
   "session.messages.loadEarlier": "Indlæs tidligere beskeder",
diff --git a/packages/app/src/i18n/de.ts b/packages/app/src/i18n/de.ts
index 4b6b43a57c00..4b6e978d6f4e 100644
--- a/packages/app/src/i18n/de.ts
+++ b/packages/app/src/i18n/de.ts
@@ -452,6 +452,8 @@ export const dict = {
   "session.files.selectToOpen": "Datei zum Öffnen auswählen",
   "session.files.all": "Alle Dateien",
   "session.files.binaryContent": "Binärdatei (Inhalt kann nicht angezeigt werden)",
+  "session.files.viewPreview": "Vorschau",
+  "session.files.viewSource": "Quelltext",
   "session.messages.renderEarlier": "Frühere Nachrichten rendern",
   "session.messages.loadingEarlier": "Lade frühere Nachrichten...",
   "session.messages.loadEarlier": "Frühere Nachrichten laden",
diff --git a/packages/app/src/i18n/en.ts b/packages/app/src/i18n/en.ts
index fd70f389ecfc..f7c52eedbe28 100644
--- a/packages/app/src/i18n/en.ts
+++ b/packages/app/src/i18n/en.ts
@@ -496,6 +496,8 @@ export const dict = {
   "session.files.selectToOpen": "Select a file to open",
   "session.files.all": "All files",
   "session.files.binaryContent": "Binary file (content cannot be displayed)",
+  "session.files.viewPreview": "Preview",
+  "session.files.viewSource": "Source",
 
   "session.messages.renderEarlier": "Render earlier messages",
   "session.messages.loadingEarlier": "Loading earlier messages...",
diff --git a/packages/app/src/i18n/es.ts b/packages/app/src/i18n/es.ts
index 135a63fef742..5895557d8d69 100644
--- a/packages/app/src/i18n/es.ts
+++ b/packages/app/src/i18n/es.ts
@@ -498,6 +498,8 @@ export const dict = {
   "session.files.selectToOpen": "Selecciona un archivo para abrir",
   "session.files.all": "Todos los archivos",
   "session.files.binaryContent": "Archivo binario (el contenido no puede ser mostrado)",
+  "session.files.viewPreview": "Vista previa",
+  "session.files.viewSource": "Código fuente",
 
   "session.messages.renderEarlier": "Renderizar mensajes anteriores",
   "session.messages.loadingEarlier": "Cargando mensajes anteriores...",
diff --git a/packages/app/src/i18n/fr.ts b/packages/app/src/i18n/fr.ts
index 1ab0c72d53a5..52c684cb5ea7 100644
--- a/packages/app/src/i18n/fr.ts
+++ b/packages/app/src/i18n/fr.ts
@@ -450,6 +450,8 @@ export const dict = {
   "session.files.selectToOpen": "Sélectionnez un fichier à ouvrir",
   "session.files.all": "Tous les fichiers",
   "session.files.binaryContent": "Fichier binaire (le contenu ne peut pas être affiché)",
+  "session.files.viewPreview": "Aperçu",
+  "session.files.viewSource": "Source",
   "session.messages.renderEarlier": "Afficher les messages précédents",
   "session.messages.loadingEarlier": "Chargement des messages précédents...",
   "session.messages.loadEarlier": "Charger les messages précédents",
diff --git a/packages/app/src/i18n/ja.ts b/packages/app/src/i18n/ja.ts
index 6f092a60f683..3d909b944099 100644
--- a/packages/app/src/i18n/ja.ts
+++ b/packages/app/src/i18n/ja.ts
@@ -442,6 +442,8 @@ export const dict = {
   "session.files.selectToOpen": "開くファイルを選択",
   "session.files.all": "すべてのファイル",
   "session.files.binaryContent": "バイナリファイル（内容を表示できません）",
+  "session.files.viewPreview": "プレビュー",
+  "session.files.viewSource": "ソース",
   "session.messages.renderEarlier": "以前のメッセージを表示",
   "session.messages.loadingEarlier": "以前のメッセージを読み込み中...",
   "session.messages.loadEarlier": "以前のメッセージを読み込む",
diff --git a/packages/app/src/i18n/ko.ts b/packages/app/src/i18n/ko.ts
index 4d814d43d0a3..85903a56b707 100644
--- a/packages/app/src/i18n/ko.ts
+++ b/packages/app/src/i18n/ko.ts
@@ -444,6 +444,8 @@ export const dict = {
   "session.files.selectToOpen": "열 파일을 선택하세요",
   "session.files.all": "모든 파일",
   "session.files.binaryContent": "바이너리 파일 (내용을 표시할 수 없음)",
+  "session.files.viewPreview": "미리보기",
+  "session.files.viewSource": "소스",
   "session.messages.renderEarlier": "이전 메시지 렌더링",
   "session.messages.loadingEarlier": "이전 메시지 로드 중...",
   "session.messages.loadEarlier": "이전 메시지 로드",
diff --git a/packages/app/src/i18n/no.ts b/packages/app/src/i18n/no.ts
index 63bc66acfcd2..bfc811f5d27b 100644
--- a/packages/app/src/i18n/no.ts
+++ b/packages/app/src/i18n/no.ts
@@ -498,6 +498,8 @@ export const dict = {
   "session.files.selectToOpen": "Velg en fil å åpne",
   "session.files.all": "Alle filer",
   "session.files.binaryContent": "Binær fil (innhold kan ikke vises)",
+  "session.files.viewPreview": "Forhåndsvisning",
+  "session.files.viewSource": "Kilde",
 
   "session.messages.renderEarlier": "Vis tidligere meldinger",
   "session.messages.loadingEarlier": "Laster inn tidligere meldinger...",
diff --git a/packages/app/src/i18n/pl.ts b/packages/app/src/i18n/pl.ts
index 2a3ea7bfb183..5f988e2d84aa 100644
--- a/packages/app/src/i18n/pl.ts
+++ b/packages/app/src/i18n/pl.ts
@@ -443,6 +443,8 @@ export const dict = {
   "session.files.selectToOpen": "Wybierz plik do otwarcia",
   "session.files.all": "Wszystkie pliki",
   "session.files.binaryContent": "Plik binarny (zawartość nie może być wyświetlona)",
+  "session.files.viewPreview": "Podgląd",
+  "session.files.viewSource": "Źródło",
   "session.messages.renderEarlier": "Renderuj wcześniejsze wiadomości",
   "session.messages.loadingEarlier": "Ładowanie wcześniejszych wiadomości...",
   "session.messages.loadEarlier": "Załaduj wcześniejsze wiadomości",
diff --git a/packages/app/src/i18n/ru.ts b/packages/app/src/i18n/ru.ts
index 93e5b274253c..58270483667b 100644
--- a/packages/app/src/i18n/ru.ts
+++ b/packages/app/src/i18n/ru.ts
@@ -497,6 +497,8 @@ export const dict = {
   "session.files.selectToOpen": "Выберите файл, чтобы открыть",
   "session.files.all": "Все файлы",
   "session.files.binaryContent": "Двоичный файл (содержимое не может быть отображено)",
+  "session.files.viewPreview": "Предпросмотр",
+  "session.files.viewSource": "Исходный код",
   "session.messages.renderEarlier": "Показать предыдущие сообщения",
   "session.messages.loadingEarlier": "Загрузка предыдущих сообщений...",
   "session.messages.loadEarlier": "Загрузить предыдущие сообщения",
diff --git a/packages/app/src/i18n/th.ts b/packages/app/src/i18n/th.ts
index 3b3486b5c700..8ddd48135951 100644
--- a/packages/app/src/i18n/th.ts
+++ b/packages/app/src/i18n/th.ts
@@ -493,6 +493,8 @@ export const dict = {
   "session.files.selectToOpen": "เลือกไฟล์เพื่อเปิด",
   "session.files.all": "ไฟล์ทั้งหมด",
   "session.files.binaryContent": "ไฟล์ไบนารี (ไม่สามารถแสดงเนื้อหาได้)",
+  "session.files.viewPreview": "ดูตัวอย่าง",
+  "session.files.viewSource": "ซอร์สโค้ด",
 
   "session.messages.renderEarlier": "แสดงข้อความก่อนหน้า",
   "session.messages.loadingEarlier": "กำลังโหลดข้อความก่อนหน้า...",
diff --git a/packages/app/src/i18n/zh.ts b/packages/app/src/i18n/zh.ts
index 6489b7025425..c2aca87130c9 100644
--- a/packages/app/src/i18n/zh.ts
+++ b/packages/app/src/i18n/zh.ts
@@ -494,6 +494,8 @@ export const dict = {
   "session.files.selectToOpen": "选择要打开的文件",
   "session.files.all": "所有文件",
   "session.files.binaryContent": "二进制文件（无法显示内容）",
+  "session.files.viewPreview": "预览",
+  "session.files.viewSource": "源代码",
   "session.messages.renderEarlier": "显示更早的消息",
   "session.messages.loadingEarlier": "正在加载更早的消息...",
   "session.messages.loadEarlier": "加载更早的消息",
diff --git a/packages/app/src/i18n/zht.ts b/packages/app/src/i18n/zht.ts
index a01b76c0521b..a100e0718a43 100644
--- a/packages/app/src/i18n/zht.ts
+++ b/packages/app/src/i18n/zht.ts
@@ -490,6 +490,8 @@ export const dict = {
   "session.files.selectToOpen": "選取要開啟的檔案",
   "session.files.all": "所有檔案",
   "session.files.binaryContent": "二進位檔案（無法顯示內容）",
+  "session.files.viewPreview": "預覽",
+  "session.files.viewSource": "原始碼",
   "session.messages.renderEarlier": "顯示更早的訊息",
   "session.messages.loadingEarlier": "正在載入更早的訊息...",
   "session.messages.loadEarlier": "載入更早的訊息",
diff --git a/packages/app/src/pages/session/file-tabs.tsx b/packages/app/src/pages/session/file-tabs.tsx
index d22fa358b028..c5499ef295ab 100644
--- a/packages/app/src/pages/session/file-tabs.tsx
+++ b/packages/app/src/pages/session/file-tabs.tsx
@@ -1,4 +1,4 @@
-import { type ValidComponent, createEffect, createMemo, For, Match, on, onCleanup, Show, Switch } from "solid-js"
+import { type ValidComponent, createEffect, createMemo, createSignal, For, Match, on, onCleanup, Show, Switch } from "solid-js"
 import { createStore, produce } from "solid-js/store"
 import { Dynamic } from "solid-js/web"
 import { sampledChecksum } from "@opencode-ai/util/encode"
@@ -7,6 +7,8 @@ import { showToast } from "@opencode-ai/ui/toast"
 import { LineComment as LineCommentView, LineCommentEditor } from "@opencode-ai/ui/line-comment"
 import { Mark } from "@opencode-ai/ui/logo"
 import { Tabs } from "@opencode-ai/ui/tabs"
+import { IconButton } from "@opencode-ai/ui/icon-button"
+import { Markdown } from "@opencode-ai/ui/markdown"
 import { useLayout } from "@/context/layout"
 import { useFile, type SelectedLineRange } from "@/context/file"
 import { useComments } from "@/context/comments"
@@ -59,6 +61,18 @@ export function FileTabContent(props: {
     return c?.mimeType === "image/svg+xml"
   })
   const isBinary = createMemo(() => state()?.content?.type === "binary")
+  const isMarkdown = createMemo(() => {
+    const p = path()
+    return p?.toLowerCase().endsWith(".md") || p?.toLowerCase().endsWith(".markdown")
+  })
+  const [previewMode, setPreviewMode] = createSignal(true)
+
+  createEffect(() => {
+    const isMarkdownFile = isMarkdown()
+    if (isMarkdownFile) {
+      setPreviewMode(true)
+    }
+  })
   const svgContent = createMemo(() => {
     if (!isSvg()) return
     const c = state()?.content
@@ -483,6 +497,28 @@ export function FileTabContent(props: {
       }}
       onScroll={handleScroll}
     >
+      <Show when={state()?.loaded && isMarkdown() && !isBinary()}>
+        <div class="sticky top-0 z-10 flex justify-end items-center gap-2 px-6 py-2 bg-background-base border-b border-border-weak-base">
+          <div class="flex items-center gap-1 bg-background-stronger rounded-md p-1">
+            <IconButton
+              icon="code"
+              size="small"
+              variant={!previewMode() ? "primary" : "ghost"}
+              onClick={() => setPreviewMode(false)}
+              aria-label={props.language.t("session.files.viewSource")}
+              title={props.language.t("session.files.viewSource")}
+            />
+            <IconButton
+              icon="eye"
+              size="small"
+              variant={previewMode() ? "primary" : "ghost"}
+              onClick={() => setPreviewMode(true)}
+              aria-label={props.language.t("session.files.viewPreview")}
+              title={props.language.t("session.files.viewPreview")}
+            />
+          </div>
+        </div>
+      </Show>
       <Switch>
         <Match when={state()?.loaded && isImage()}>
           <div class="px-6 py-4 pb-40">
@@ -513,6 +549,11 @@ export function FileTabContent(props: {
             </div>
           </div>
         </Match>
+        <Match when={state()?.loaded && isMarkdown() && previewMode()}>
+          <div class="px-6 py-4 pb-40">
+            <Markdown text={contents()} cacheKey={cacheKey()} />
+          </div>
+        </Match>
         <Match when={state()?.loaded}>{renderCode(contents(), "pb-40")}</Match>
         <Match when={state()?.loading}>
           <div class="px-6 py-4 text-text-weak">{props.language.t("common.loading")}...</div>