validate retrieve --k must be > 0

src/contextseek/cli/main.py

@@ -55,6 +55,16 @@ def _resolve_scope(args: argparse.Namespace, default_scope: str) -> str:
     return scope
 
 
+def _positive_int(value: str) -> int:
+    """Validate and parse a positive integer (> 0)."""
+    n = int(value)
+    if n <= 0:
+        raise argparse.ArgumentTypeError(
+            f"invalid positive int value: {value!r} (must be > 0)"
+        )
+    return n
+
+
 def build_parser() -> argparse.ArgumentParser:
     """Build CLI parser for commands."""
     parser = argparse.ArgumentParser(prog="contextseek")
@@ -73,7 +83,7 @@ def build_parser() -> argparse.ArgumentParser:
     )
     retrieve_parser.add_argument("--scope", default=None)
     retrieve_parser.add_argument("--query", required=True)
-    retrieve_parser.add_argument("--k", type=int, default=10)
+    retrieve_parser.add_argument("--k", type=_positive_int, default=10)
     retrieve_parser.add_argument(
         "--full",
         action="store_true",

tests/unit_tests/test_cli.py

@@ -0,0 +1,52 @@
+"""Tests for CLI argument parsing and validation."""
+
+import argparse
+from contextlib import redirect_stderr
+from io import StringIO
+
+import pytest
+
+from contextseek.cli.main import build_parser, _positive_int
+
+
+class TestPositiveInt:
+    def test_positive_value(self):
+        assert _positive_int("5") == 5
+        assert _positive_int("1") == 1
+
+    def test_zero_raises(self):
+        with pytest.raises(argparse.ArgumentTypeError, match="must be > 0"):
+            _positive_int("0")
+
+    def test_negative_raises(self):
+        with pytest.raises(argparse.ArgumentTypeError, match="must be > 0"):
+            _positive_int("-1")
+
+    def test_non_integer_raises(self):
+        with pytest.raises(ValueError):
+            _positive_int("abc")
+
+
+class TestRetrieveKValidation:
+    def test_k_zero_rejected(self) -> None:
+        parser = build_parser()
+        err = StringIO()
+        with redirect_stderr(err), pytest.raises(SystemExit):
+            parser.parse_args(["retrieve", "--scope", "t", "--query", "q", "--k", "0"])
+        assert "must be > 0" in err.getvalue()
+
+    def test_k_negative_rejected(self) -> None:
+        parser = build_parser()
+        err = StringIO()
+        with redirect_stderr(err), pytest.raises(SystemExit):
+            parser.parse_args(
+                ["retrieve", "--scope", "t", "--query", "q", "--k", "-1"]
+            )
+        assert "must be > 0" in err.getvalue()
+
+    def test_k_positive_accepted(self) -> None:
+        parser = build_parser()
+        args = parser.parse_args(
+            ["retrieve", "--scope", "t", "--query", "q", "--k", "5"]
+        )
+        assert args.k == 5