diff --git a/agent/copilot_acp_client.py b/agent/copilot_acp_client.py
index 027defa22b..457b32b37b 100644
--- a/agent/copilot_acp_client.py
+++ b/agent/copilot_acp_client.py
@@ -477,8 +477,8 @@ class CopilotACPClient:
             proc.stdin.write(json.dumps(payload) + "\n")
             proc.stdin.flush()
 
-            deadline = time.time() + timeout_seconds
-            while time.time() < deadline:
+            deadline = time.monotonic() + timeout_seconds
+            while time.monotonic() < deadline:
                 if proc.poll() is not None:
                     break
                 try:
diff --git a/hermes_cli/auth.py b/hermes_cli/auth.py
index 0e12e7157d..1bcb1af77f 100644
--- a/hermes_cli/auth.py
+++ b/hermes_cli/auth.py
@@ -894,7 +894,7 @@ def _file_lock(
         lock_path.write_text(" ", encoding="utf-8")
 
     with lock_path.open("r+" if msvcrt else "a+") as lock_file:
-        deadline = time.time() + max(1.0, timeout_seconds)
+        deadline = time.monotonic() + max(1.0, timeout_seconds)
         while True:
             try:
                 if fcntl:
@@ -904,7 +904,7 @@ def _file_lock(
                     msvcrt.locking(lock_file.fileno(), msvcrt.LK_NBLCK, 1)
                 break
             except (BlockingIOError, OSError, PermissionError):
-                if time.time() >= deadline:
+                if time.monotonic() >= deadline:
                     raise TimeoutError(timeout_message)
                 time.sleep(0.05)
 
@@ -1974,9 +1974,9 @@ def _spotify_wait_for_callback(
 
     thread = threading.Thread(target=server.serve_forever, kwargs={"poll_interval": 0.1}, daemon=True)
     thread.start()
-    deadline = time.time() + max(5.0, timeout_seconds)
+    deadline = time.monotonic() + max(5.0, timeout_seconds)
     try:
-        while time.time() < deadline:
+        while time.monotonic() < deadline:
             if result["code"] or result["error"]:
                 return result
             time.sleep(0.1)
@@ -2739,10 +2739,10 @@ def _poll_for_token(
     poll_interval: int,
 ) -> Dict[str, Any]:
     """Poll the token endpoint until the user approves or the code expires."""
-    deadline = time.time() + max(1, expires_in)
+    deadline = time.monotonic() + max(1, expires_in)
     current_interval = max(1, min(poll_interval, DEVICE_AUTH_POLL_INTERVAL_CAP_SECONDS))
 
-    while time.time() < deadline:
+    while time.monotonic() < deadline:
         response = client.post(
             f"{portal_base_url}/api/oauth/token",
             data={
diff --git a/hermes_cli/copilot_auth.py b/hermes_cli/copilot_auth.py
index 348e4efe83..7475f80a2b 100644
--- a/hermes_cli/copilot_auth.py
+++ b/hermes_cli/copilot_auth.py
@@ -212,9 +212,9 @@ def copilot_device_code_login(
     print("  Waiting for authorization...", end="", flush=True)
 
     # Step 3: Poll for completion
-    deadline = time.time() + timeout_seconds
+    deadline = time.monotonic() + timeout_seconds
 
-    while time.time() < deadline:
+    while time.monotonic() < deadline:
         time.sleep(interval + _DEVICE_CODE_POLL_SAFETY_MARGIN)
 
         poll_data = urllib.parse.urlencode({
diff --git a/hermes_cli/gateway.py b/hermes_cli/gateway.py
index 232f8dac80..c751ced8ae 100644
--- a/hermes_cli/gateway.py
+++ b/hermes_cli/gateway.py
@@ -585,10 +585,10 @@ def _wait_for_systemd_service_restart(
 
     svc = get_service_name()
     scope_label = _service_scope_label(system).capitalize()
-    deadline = time.time() + timeout
+    deadline = time.monotonic() + timeout
     printed_runtime_wait = False
 
-    while time.time() < deadline:
+    while time.monotonic() < deadline:
         props = _read_systemd_unit_properties(system=system)
         active_state = props.get("ActiveState", "")
         sub_state = props.get("SubState", "")
diff --git a/hermes_cli/web_server.py b/hermes_cli/web_server.py
index 5469cff607..5527039cf1 100644
--- a/hermes_cli/web_server.py
+++ b/hermes_cli/web_server.py
@@ -1877,8 +1877,8 @@ async def _start_device_code_flow(provider_id: str) -> Dict[str, Any]:
             name=f"oauth-codex-{sid[:6]}",
         ).start()
         # Block briefly until the worker has populated the user_code, OR error.
-        deadline = time.time() + 10
-        while time.time() < deadline:
+        deadline = time.monotonic() + 10
+        while time.monotonic() < deadline:
             with _oauth_sessions_lock:
                 s = _oauth_sessions.get(sid)
             if s and (s.get("user_code") or s["status"] != "pending"):
@@ -2012,10 +2012,10 @@ def _codex_full_login_worker(session_id: str) -> None:
             sess["expires_at"] = time.time() + sess["expires_in"]
 
         # Step 2: poll until authorized
-        deadline = time.time() + sess["expires_in"]
+        deadline = time.monotonic() + sess["expires_in"]
         code_resp = None
         with httpx.Client(timeout=httpx.Timeout(15.0)) as client:
-            while time.time() < deadline:
+            while time.monotonic() < deadline:
                 time.sleep(poll_interval)
                 poll = client.post(
                     f"{issuer}/api/accounts/deviceauth/token",