diff --git a/tests/tools/test_process_heartbeat.py b/tests/tools/test_process_heartbeat.py
index 7c5f9626f7219..fed9b06de8587 100644
--- a/tests/tools/test_process_heartbeat.py
+++ b/tests/tools/test_process_heartbeat.py
@@ -63,7 +63,7 @@ def test_heartbeat_carries_only_new_output_and_stops_at_exit(tmp_path, monkeypat
                            timeout=2.5)
 
 
-def test_terminal_dispatch_heartbeat_implies_notify_and_refuses_foreground(monkeypatch):
+def test_terminal_dispatch_normalizes_materialized_background_fields_for_foreground(monkeypatch):
     from tools import terminal_tool as tt
 
     captured = {}
@@ -74,8 +74,17 @@ def fake_terminal_tool(**kwargs):
 
     monkeypatch.setattr(tt, "terminal_tool", fake_terminal_tool)
     dispatch = tt._handle_terminal
-    fg = json.loads(dispatch({"command": "sleep 1", "heartbeat": 120}))
-    assert fg.get("error") and "background" in fg["error"]
+    fg = json.loads(dispatch({
+        "command": "sleep 1",
+        "background": False,
+        "notify": False,
+        "heartbeat": 60,
+    }))
+    assert "error" not in fg or not fg["error"]
+    assert captured["heartbeat"] == 0 and captured["notify_on_complete"] is False
+
+    foreground_notify = json.loads(dispatch({"command": "sleep 1", "notify": True}))
+    assert foreground_notify.get("error") and "background" in foreground_notify["error"]
 
     bg = json.loads(dispatch({"command": "sleep 1", "background": True, "heartbeat": 120}))
     assert "error" not in bg or not bg["error"]
diff --git a/tools/terminal_tool.py b/tools/terminal_tool.py
index 80cfaf9fd0469..2e9bae49db3d7 100644
--- a/tools/terminal_tool.py
+++ b/tools/terminal_tool.py
@@ -1411,8 +1411,9 @@ def _handle_terminal(args, **kw):
         )
     # `notify` is the advertised interface (true → notify_on_complete,
     # [...] → watch_patterns); the legacy args stay accepted, explicit
-    # `notify` wins. Background-only modifiers on a foreground call fail
-    # with the corrected call instead of being silently ignored.
+    # `notify` wins. Tool schemas mechanically materialize false background
+    # defaults and a heartbeat for ordinary foreground calls, so discard those
+    # non-operative fields instead of making the model retry the same command.
     notify = args.get("notify")
     notify_on_complete = args.get("notify_on_complete", False)
     watch_patterns = args.get("watch_patterns")
@@ -1420,12 +1421,13 @@ def _handle_terminal(args, **kw):
     if not isinstance(heartbeat, int) or isinstance(heartbeat, bool) or heartbeat < 0:
         return tool_error("heartbeat must be a whole number of seconds (min 60).")
     if not args.get("background", False):
-        if notify or watch_patterns or notify_on_complete or heartbeat:
+        if notify or watch_patterns or notify_on_complete:
             return tool_error(
                 "notify/heartbeat only apply to background commands (foreground "
                 "results return directly). Either drop them, or run as "
                 "terminal(command=..., background=true, notify=...)."
             )
+        heartbeat = 0
         if args.get("pty", False):
             return tool_error(
                 "pty requires background=true (a PTY session is interacted "