diff --git a/src/tenantq/cli.py b/src/tenantq/cli.py
index 783b347..6798001 100644
--- a/src/tenantq/cli.py
+++ b/src/tenantq/cli.py
@@ -5,6 +5,7 @@
 import json
 from typing import List, Optional
 
+import click
 import typer
 
 from .benchmark import BenchmarkResult, run_benchmark
@@ -112,7 +113,7 @@ def benchmark(
 def search(
     query: str,
     tenant: str = typer.Option(..., help="Tenant id to scope the search."),
-    mode: str = typer.Option("hybrid"),
+    mode: str = typer.Option("hybrid", click_type=click.Choice(["dense", "sparse", "hybrid"])),
     limit: int = typer.Option(5),
     category: Optional[str] = typer.Option(None),
     embedder: str = typer.Option("fastembed"),
diff --git a/tests/test_cli.py b/tests/test_cli.py
new file mode 100644
index 0000000..01cb8e8
--- /dev/null
+++ b/tests/test_cli.py
@@ -0,0 +1,20 @@
+"""CLI behaviour: option validation surfaces clean usage errors."""
+
+from __future__ import annotations
+
+import pytest
+from typer.testing import CliRunner
+
+from tenantq.cli import app
+
+runner = CliRunner()
+
+
+@pytest.mark.parametrize("bad_mode", ["hybird", "HYBRID", "dense "])
+def test_search_rejects_unknown_mode(bad_mode):
+    result = runner.invoke(app, ["search", "neural network", "--tenant", "acme", "--mode", bad_mode])
+    assert result.exit_code != 0
+    assert result.exception is not None
+    message = str(result.exception)
+    assert "hybrid" in message
+    assert "is not one of" in message