diff --git a/src/hooks/auto-slash-command/hook.ts b/src/hooks/auto-slash-command/hook.ts
index 1803394d1..8b2c4a58e 100644
--- a/src/hooks/auto-slash-command/hook.ts
+++ b/src/hooks/auto-slash-command/hook.ts
@@ -56,6 +56,16 @@ function getCommandExecutionEventID(input: CommandExecuteBeforeInput): string |
   return null
 }
 
+function partsContainAutoSlashCommandTags(parts: Array<{ text?: string }>): boolean {
+  return parts.some((part) =>
+    typeof part.text === "string"
+    && (
+      part.text.includes(AUTO_SLASH_COMMAND_TAG_OPEN)
+      || part.text.includes(AUTO_SLASH_COMMAND_TAG_CLOSE)
+    )
+  )
+}
+
 export interface AutoSlashCommandHookOptions {
   skills?: LoadedSkill[]
   pluginsEnabled?: boolean
@@ -153,6 +163,10 @@ export function createAutoSlashCommandHook(options?: AutoSlashCommandHookOptions
       input: CommandExecuteBeforeInput,
       output: CommandExecuteBeforeOutput
     ): Promise<void> => {
+      if (partsContainAutoSlashCommandTags(output.parts)) {
+        return
+      }
+
       const eventID = getCommandExecutionEventID(input)
       const commandKey = eventID
         ? `${input.sessionID}:event:${eventID}`
diff --git a/src/hooks/auto-slash-command/index.test.ts b/src/hooks/auto-slash-command/index.test.ts
index 56d6dbbed..70e8d81c9 100644
--- a/src/hooks/auto-slash-command/index.test.ts
+++ b/src/hooks/auto-slash-command/index.test.ts
@@ -355,6 +355,22 @@ describe("createAutoSlashCommandHook", () => {
       expect(output.parts[0].text).toContain("/ralph-loop Command")
     })
 
+    it("should not duplicate injection when command output is already tagged", async () => {
+      //#given
+      const hook = createAutoSlashCommandHook()
+      const input = createCommandInput("ralph-loop")
+      const taggedContent = "<auto-slash-command>\n/ralph-loop Command\n</auto-slash-command>"
+      const output = createCommandOutput(taggedContent)
+
+      //#when
+      await hook["command.execute.before"](input, output)
+
+      //#then
+      expect(output.parts).toHaveLength(1)
+      expect(output.parts[0]?.text).toBe(taggedContent)
+      expect(output.parts[0]?.text?.split("<auto-slash-command>").length).toBe(2)
+    })
+
     it("should inject template for known builtin commands like ulw-loop", async () => {
       //#given
       const hook = createAutoSlashCommandHook()