diff --git a/apps/web/src/components/chat/ChatComposer.tsx b/apps/web/src/components/chat/ChatComposer.tsx
index d7878cc29a165..56c73bcec16a6 100644
--- a/apps/web/src/components/chat/ChatComposer.tsx
+++ b/apps/web/src/components/chat/ChatComposer.tsx
@@ -133,6 +133,7 @@ import {
 import { attachmentUploadBlockReason } from "../../lib/attachmentUploadState";
 import type { AssistantCitationSourceAnchor } from "~/lib/assistantTextSelection";
 import { shortcutLabelForCommand } from "../../keybindings";
+import { persistClientSettingsUpdate } from "../../hooks/useSettings";
 import {
   type TerminalContextDraft,
   type TerminalContextSelection,
@@ -198,6 +199,7 @@ import {
   ComposerRestingImagePreviews,
 } from "./ComposerAttachmentStrip";
 import { ComposerPrimaryActions } from "./ComposerPrimaryActions";
+import { ComposerRichTextToggle } from "./ComposerRichTextToggle";
 import { ComposerFooterPrimaryActions } from "./ComposerFooterControls";
 import { ComposerPendingUserInputPanel } from "./ComposerPendingUserInputPanel";
 import { ComposerPlanFollowUpBanner } from "./ComposerPlanFollowUpBanner";
@@ -304,6 +306,7 @@ export interface ChatComposerHandle {
   openModelPicker: () => void;
   stepReasoningEffort: (direction: 1 | -1) => void;
   toggleModelPicker: () => void;
+  toggleRichText: () => void;
   openControl: (command: KeybindingCommand) => void;
   isModelPickerOpen: () => boolean;
   isCaretAtStart: () => boolean;
@@ -2852,6 +2855,13 @@ export const ChatComposer = memo(function ChatComposer(props: ChatComposerProps)
           openModelPickerStable();
         }
       },
+      toggleRichText: () => {
+        if (isLiteralPendingAnswer) return;
+        persistClientSettingsUpdate((current) => ({
+          ...current,
+          composerRichTextEnabled: !current.composerRichTextEnabled,
+        })).catch(console.error);
+      },
       openControl: (command) => {
         if (composerBlurFrameRef.current !== null) {
           window.cancelAnimationFrame(composerBlurFrameRef.current);
@@ -3429,7 +3439,23 @@ export const ChatComposer = memo(function ChatComposer(props: ChatComposerProps)
                   showMobilePendingAnswerActions && "hidden sm:flex",
                 )}
               >
-                {composerAttachButton ? <div className="me-2">{composerAttachButton}</div> : null}
+                {composerAttachButton || !isLiteralPendingAnswer ? (
+                  <div className="me-2 flex items-center gap-0.5">
+                    {composerAttachButton}
+                    {isLiteralPendingAnswer ? null : (
+                      <ComposerRichTextToggle
+                        richTextEnabled={settings.composerRichTextEnabled}
+                        shortcutLabel={shortcutLabelForCommand(
+                          keybindings,
+                          "composer.toggleRichText",
+                          {
+                            context: { terminalFocus: false, terminalOpen, modelPickerOpen: false },
+                          },
+                        )}
+                      />
+                    )}
+                  </div>
+                ) : null}
                 <div
                   data-chat-composer-actions="right"
                   data-chat-composer-transition-actions="true"
diff --git a/apps/web/src/components/chat/ComposerRichTextToggle.tsx b/apps/web/src/components/chat/ComposerRichTextToggle.tsx
new file mode 100644
index 0000000000000..b705180c20993
--- /dev/null
+++ b/apps/web/src/components/chat/ComposerRichTextToggle.tsx
@@ -0,0 +1,41 @@
+import { FeatherIcon } from "lucide-react";
+
+import { updateClientSettings } from "../../hooks/useSettings";
+import { Button } from "../ui/button";
+import { Tooltip, TooltipPopup, TooltipTrigger } from "../ui/tooltip";
+
+// Same setting as Settings → Chat → Rich text composer. Flipping it remounts the
+// editor; pointer-down is swallowed so a focused editor keeps its caret across that.
+export function ComposerRichTextToggle({
+  richTextEnabled,
+  shortcutLabel,
+}: {
+  readonly richTextEnabled: boolean;
+  readonly shortcutLabel: string | null;
+}) {
+  const showingSource = !richTextEnabled;
+  return (
+    <Tooltip>
+      <TooltipTrigger
+        render={
+          <Button
+            type="button"
+            variant="ghost"
+            size="icon-sm"
+            aria-label="Markdown source"
+            aria-pressed={showingSource}
+            data-pressed={showingSource ? "" : undefined}
+            onPointerDown={(event) => event.preventDefault()}
+            onClick={() => void updateClientSettings({ composerRichTextEnabled: showingSource })}
+          />
+        }
+      >
+        <FeatherIcon />
+      </TooltipTrigger>
+      <TooltipPopup>
+        {showingSource ? "Show formatting" : "Show Markdown source"}
+        {shortcutLabel ? ` · ${shortcutLabel}` : null}
+      </TooltipPopup>
+    </Tooltip>
+  );
+}
diff --git a/apps/web/src/components/chat/composerShortcuts.ts b/apps/web/src/components/chat/composerShortcuts.ts
index 30beb9771968f..e55398996cea9 100644
--- a/apps/web/src/components/chat/composerShortcuts.ts
+++ b/apps/web/src/components/chat/composerShortcuts.ts
@@ -18,6 +18,12 @@ export function composerShortcutCommands(
     "modelPicker.toggle": ({ event }) => {
       if (!event.repeat) composerRef.current?.toggleModelPicker();
     },
+    "composer.toggleRichText": ({ event }) => {
+      // The flip remounts the editor, which would drop an unsaved citation comment.
+      if (event.target instanceof Element && event.target.closest("[data-citation-comment-editor]"))
+        return false;
+      if (!event.repeat) composerRef.current?.toggleRichText();
+    },
     "composer.increaseEffort": ({ event }) => {
       if (!event.repeat) composerRef.current?.stepReasoningEffort(1);
     },
diff --git a/apps/web/src/keybindings.test.ts b/apps/web/src/keybindings.test.ts
index a0ba7fa7ee043..96ae09296dea5 100644
--- a/apps/web/src/keybindings.test.ts
+++ b/apps/web/src/keybindings.test.ts
@@ -768,12 +768,21 @@ describe("composer and pull request shortcuts", () => {
   });
 
   it.each(["MacIntel", "Win32", "Linux"])(
-    "reserves the alternate send chord for the focused composer on %s",
+    "resolves composer toggle and alternate send chords in their contexts on %s",
     (platform) => {
       const modifier = {
         metaKey: platform === "MacIntel",
         ctrlKey: platform !== "MacIntel",
       };
+      for (const terminalFocus of [false, true]) {
+        assert.strictEqual(
+          resolveShortcutCommand(event({ key: "/", ...modifier }), DEFAULT_RESOLVED_KEYBINDINGS, {
+            platform,
+            context: { terminalFocus },
+          }),
+          terminalFocus ? null : "composer.toggleRichText",
+        );
+      }
       const shiftedEnter = event({ key: "Enter", shiftKey: true, ...modifier });
       for (const composerRequiresModifier of [false, true]) {
         const context = {
diff --git a/docs/user/composer.md b/docs/user/composer.md
index 714572dfd5005..afac8ce64cf3b 100644
--- a/docs/user/composer.md
+++ b/docs/user/composer.md
@@ -19,7 +19,9 @@ The composer writes Markdown and shows it styled as you type. Markers such as
 them. Lines starting with `- `, `1. `, `- [ ] `, `> `, `# ` or `---` become lists,
 task lists, quotes, headings and rules; ` ``` ` followed by Enter opens a code
 block. What you typed is what the agent receives, markers and numbering
-included, and `#1234` without a space still looks up a pull request.
+included, and `#1234` without a space still looks up a pull request. To see the
+plain Markdown instead, press the button beside attach; it is the same
+switch as **Settings → Chat → Rich text composer**.
 
 Enter sends. In a list or quote, **Shift+Enter** continues it, and Shift+Enter
 on an empty line moves out one level, then leaves it; **Tab** nests a list item
diff --git a/docs/user/keybindings.md b/docs/user/keybindings.md
index 83989762c5b07..0e8e17744019e 100644
--- a/docs/user/keybindings.md
+++ b/docs/user/keybindings.md
@@ -28,6 +28,7 @@ Use `mod+shift+e` for effort, `mod+shift+a` for permissions, `mod+shift+x` for t
 workspace, and `mod+shift+g` for the Git branch. The workspace menu includes the
 current checkout, a new worktree, and the previous worktree when available.
 Use `mod+shift+l` to reuse the previous worktree directly.
+Use `mod+/` to switch the composer between rich text and its Markdown source.
 
 To change effort one step without opening the picker, bind
 **Composer: Increase Effort** and **Composer: Decrease Effort** in Keybindings.
diff --git a/packages/contracts/src/keybindings.ts b/packages/contracts/src/keybindings.ts
index 714e0a1d486a1..cc55adb9ca81b 100644
--- a/packages/contracts/src/keybindings.ts
+++ b/packages/contracts/src/keybindings.ts
@@ -87,6 +87,7 @@ export const STATIC_KEYBINDING_COMMANDS = [
   "appearance.cycle",
   "themeEditor.toggle",
   "composer.stash",
+  "composer.toggleRichText",
   "composer.sendAlternate",
   "composer.sendBackground",
   "composer.sendAndNewThread",
diff --git a/packages/shared/src/keybindings.ts b/packages/shared/src/keybindings.ts
index 32292c0f9ef21..8ae3f052afede 100644
--- a/packages/shared/src/keybindings.ts
+++ b/packages/shared/src/keybindings.ts
@@ -179,6 +179,7 @@ export const DEFAULT_KEYBINDINGS: ReadonlyArray<KeybindingRule> = [
   { key: "mod+alt+shift+a", command: "appearance.cycle", when: "!terminalFocus" },
   { key: "mod+alt+shift+t", command: "themeEditor.toggle" },
   { key: "mod+s", command: "composer.stash", when: "!terminalFocus" },
+  { key: "mod+/", command: "composer.toggleRichText", when: "!terminalFocus" },
   { key: "mod+shift+enter", command: "thread.steerQueuedMessage", when: "!terminalFocus" },
   { key: "alt+arrowup", command: "thread.editQueuedMessage", when: "composerFocus" },
   { key: "mod+enter", command: "composer.sendAlternate", when: "composerFocus && turnRunning" },