diff --git a/tests/tools/test_parse_env_var.py b/tests/tools/test_parse_env_var.py
index cffee7c9af..8cbbce6985 100644
--- a/tests/tools/test_parse_env_var.py
+++ b/tests/tools/test_parse_env_var.py
@@ -1,5 +1,6 @@
 """Tests for _parse_env_var and _get_env_config env-var validation."""
 
+import importlib
 import json
 from unittest.mock import patch
 
@@ -84,3 +85,23 @@ class TestParseEnvVar:
         with patch.dict("os.environ", {"TERMINAL_DOCKER_VOLUMES": "not json"}):
             with pytest.raises(ValueError, match="valid JSON"):
                 _parse_env_var("TERMINAL_DOCKER_VOLUMES", "[]", json.loads, "valid JSON")
+
+
+class TestImportTimeEnvParsing:
+    """Module-level env parsing should never make terminal_tool unimportable."""
+
+    def test_invalid_foreground_timeout_falls_back_to_default(self):
+        try:
+            with patch.dict("os.environ", {"TERMINAL_MAX_FOREGROUND_TIMEOUT": "5m"}, clear=False):
+                mod = importlib.reload(_tt_mod)
+                assert mod.FOREGROUND_MAX_TIMEOUT == 600
+        finally:
+            importlib.reload(_tt_mod)
+
+    def test_invalid_disk_warning_threshold_falls_back_to_default(self):
+        try:
+            with patch.dict("os.environ", {"TERMINAL_DISK_WARNING_GB": "huge"}, clear=False):
+                mod = importlib.reload(_tt_mod)
+                assert mod.DISK_USAGE_WARNING_THRESHOLD_GB == 500.0
+        finally:
+            importlib.reload(_tt_mod)
diff --git a/tools/terminal_tool.py b/tools/terminal_tool.py
index 4a2a5fc0be..8fbffadc94 100644
--- a/tools/terminal_tool.py
+++ b/tools/terminal_tool.py
@@ -72,11 +72,48 @@ from tools.tool_backend_helpers import (
 )
 
 
+def _safe_parse_import_env(
+    name: str,
+    default: Any,
+    converter,
+    type_label: str,
+):
+    """Parse module-level numeric env vars without breaking import.
+
+    Terminal tool is imported by CLI, ACP, tests, and tool discovery. A single
+    malformed env var must not make the whole module unloadable at import time.
+    """
+    raw = os.getenv(name)
+    if raw is None or raw == "":
+        return default
+    try:
+        return converter(raw)
+    except (TypeError, ValueError):
+        logger.warning(
+            "Invalid value for %s: %r (expected %s). Falling back to %r.",
+            name,
+            raw,
+            type_label,
+            default,
+        )
+        return default
+
+
 # Hard cap on foreground timeout; override via TERMINAL_MAX_FOREGROUND_TIMEOUT env var.
-FOREGROUND_MAX_TIMEOUT = int(os.getenv("TERMINAL_MAX_FOREGROUND_TIMEOUT", "600"))
+FOREGROUND_MAX_TIMEOUT = _safe_parse_import_env(
+    "TERMINAL_MAX_FOREGROUND_TIMEOUT",
+    600,
+    int,
+    "integer",
+)
 
 # Disk usage warning threshold (in GB)
-DISK_USAGE_WARNING_THRESHOLD_GB = float(os.getenv("TERMINAL_DISK_WARNING_GB", "500"))
+DISK_USAGE_WARNING_THRESHOLD_GB = _safe_parse_import_env(
+    "TERMINAL_DISK_WARNING_GB",
+    500.0,
+    float,
+    "number",
+)
 
 
 def _check_disk_usage_warning():