Print help when command is empty and no input redirect

Author: daonb

llm/cli.py

@@ -143,6 +143,11 @@ def prompt(
 
     Documentation: https://llm.datasette.io/en/stable/usage.html
     """
+    # If no prompt is provided, and we are in a TTY, show the help
+    if sys.stdin.isatty() and not prompt:
+        click.echo(click.Context(cli).get_help())
+        return
+
     if log and no_log:
         raise click.ClickException("--log and --no-log are mutually exclusive")
 
@@ -153,18 +158,14 @@ def read_prompt():
 
         # Is there extra prompt available on stdin?
         stdin_prompt = None
-        if not sys.stdin.isatty():
-            stdin_prompt = sys.stdin.read()
+        stdin_prompt = sys.stdin.read()
 
         if stdin_prompt:
             bits = [stdin_prompt]
             if prompt:
                 bits.append(prompt)
             prompt = " ".join(bits)
 
-        if prompt is None and not save and sys.stdin.isatty():
-            # Hang waiting for input to stdin (unless --save)
-            prompt = sys.stdin.read()
         return prompt
 
     if save:

tests/test_llm.py

@@ -570,3 +570,16 @@ def test_model_defaults(tmpdir, monkeypatch):
     assert config_path.exists()
     assert llm.get_default_model() == "gpt-4o"
     assert llm.get_model().model_id == "gpt-4o"
+
+
+def test_interactive_llm_empty_prompt():
+    runner = CliRunner()
+    # use a pty for stdin
+    master, _ = os.openpty()
+    input = os.fdopen(master, "r")
+    args = ["--no-stream"]
+    result = runner.invoke(cli, args, input=input, catch_exceptions=False)
+    assert result.exit_code == 0
+    # ensure the result is the help message
+    assert result.output.startswith("Usage:")
+    input.close()