test(non-interactive-env): add idempotency test for env prefix injection

src/hooks/non-interactive-env/index.test.ts

@@ -111,6 +111,34 @@ describe("non-interactive-env hook", () => {
 
       expect(output.args.command).toBeUndefined()
     })
+
+    test("#given git command already has prefix #when hook executes again #then does not duplicate prefix", async () => {
+      const hook = createNonInteractiveEnvHook(mockCtx)
+      
+      // First call: transforms the command
+      const output1: { args: Record<string, unknown>; message?: string } = {
+        args: { command: "git commit -m 'test'" },
+      }
+      await hook["tool.execute.before"](
+        { tool: "bash", sessionID: "test", callID: "1" },
+        output1
+      )
+      
+      const firstResult = output1.args.command as string
+      expect(firstResult).toStartWith("export ")
+      
+      // Second call: takes the already-prefixed command
+      const output2: { args: Record<string, unknown>; message?: string } = {
+        args: { command: firstResult },
+      }
+      await hook["tool.execute.before"](
+        { tool: "bash", sessionID: "test", callID: "2" },
+        output2
+      )
+      
+      // Should be exactly the same (no double prefix)
+      expect(output2.args.command).toBe(firstResult)
+    })
   })
 
   describe("shell escaping", () => {