diff --git a/scripts/mma_exec.py b/scripts/mma_exec.py
index 9c8cc1a..b2a6155 100644
--- a/scripts/mma_exec.py
+++ b/scripts/mma_exec.py
@@ -198,10 +198,10 @@ def execute_agent(role: str, prompt: str, docs: list[str]) -> str:
     command_text += f"\n\nTASK: {prompt}\n\n"
 
     # Use subprocess with input to pipe the prompt via stdin, avoiding WinError 206.
-    # We use -p '-' to read from stdin if supported, otherwise just a placeholder that stdin appends to.
+    # We use -p 'mma_task' to ensure non-interactive (headless) mode and valid parsing.
     ps_command = (
         f"if (Test-Path 'C:\\projects\\misc\\setup_gemini.ps1') {{ . 'C:\\projects\\misc\\setup_gemini.ps1' }}; "
-        f"gemini -p '---' --output-format json --model {model}"
+        f"gemini -p 'mma_task' --output-format json --model {model}"
     )
     cmd = ['powershell.exe', '-NoProfile', '-Command', ps_command]