diff --git a/src/auto-reply/commands-registry.data.ts b/src/auto-reply/commands-registry.data.ts
index 98b2d5f1e28..19ed6fb82bf 100644
--- a/src/auto-reply/commands-registry.data.ts
+++ b/src/auto-reply/commands-registry.data.ts
@@ -196,6 +196,14 @@ function buildChatCommands(): ChatCommandDefinition[] {
       acceptsArgs: true,
       category: "status",
     }),
+    defineChatCommand({
+      key: "fast",
+      description: "Show or change fast mode for this session.",
+      textAlias: "/fast",
+      acceptsArgs: true,
+      scope: "text",
+      category: "status",
+    }),
     defineChatCommand({
       key: "cortex",
       description: "Inspect or override Cortex prompt mode for this conversation.",
diff --git a/src/auto-reply/commands-registry.test.ts b/src/auto-reply/commands-registry.test.ts
index 400cccd32ad..fe63dc6b474 100644
--- a/src/auto-reply/commands-registry.test.ts
+++ b/src/auto-reply/commands-registry.test.ts
@@ -199,6 +199,13 @@ describe("commands registry", () => {
     ]);
   });
 
+  it("registers /fast as a text command", () => {
+    const fast = listChatCommands().find((command) => command.key === "fast");
+    expect(fast).toBeTruthy();
+    expect(fast?.scope).toBe("text");
+    expect(fast?.textAliases).toContain("/fast");
+  });
+
   it("invalidates cached command lists after plugin registry updates", () => {
     const before = listChatCommands();
     expect(before.find((command) => command.key === "dock:msteams")).toBeFalsy();