cowork: schema command error-path hardening + honest sample footer

src/datamorph/cli.py

@@ -176,8 +176,18 @@ def schema_cmd(
         err_console.print(f"[red]Could not detect format for: {file}[/red]")
         sys.exit(1)
 
-    reader = get_reader(fmt)
-    schema = reader.infer_schema(file, sample_size=sample)
+    try:
+        reader = get_reader(fmt)
+    except ValueError as e:
+        err_console.print(f"[red]ERROR:[/red] {e}")
+        sys.exit(1)
+    try:
+        schema = reader.infer_schema(file, sample_size=sample)
+    except Exception as e:
+        err_console.print(
+            f"[red]ERROR:[/red] Could not infer schema from {file}: {e}"
+        )
+        sys.exit(1)
 
     if json_output:
         console.print(json.dumps(schema, indent=2))
@@ -192,7 +202,7 @@ def schema_cmd(
 
     console.print(f"\nDetected format: [bold]{fmt}[/bold]")
     console.print(table)
-    console.print(f"[dim]Inferred from {sample}+ rows[/dim]")
+    console.print(f"[dim]Inferred from a sample of up to {sample} rows[/dim]")
 
 
 # ── formats ──────────────────────────────────────────────────────────

tests/test_cli_error_paths.py

@@ -31,3 +31,35 @@ def test_convert_nonexistent_file(self):
         """convert subcommand with nonexistent file shows error."""
         result = runner.invoke(cli, ["convert", "/nonexistent/file.json"])
         assert result.exit_code != 0
+
+
+class TestSchemaCmdErrorPaths:
+    """Tests for the `schema` subcommand error paths (silent-failure class)."""
+
+    def test_schema_unsupported_format_exits_cleanly(self, tmp_path):
+        """--format with an unsupported name errors instead of traceback."""
+        f = tmp_path / "data.txt"
+        f.write_text("hello")
+        result = runner.invoke(cli, ["schema", str(f), "--format", "nope"])
+        assert result.exit_code == 1
+        assert "Unsupported format" in result.output
+        assert "Traceback" not in result.output
+
+    def test_schema_malformed_json_exits_cleanly(self, tmp_path):
+        """Malformed input yields a clean error, not an unhandled traceback."""
+        f = tmp_path / "broken.json"
+        f.write_text("{not valid json!!!")
+        result = runner.invoke(cli, ["schema", str(f)])
+        assert result.exit_code == 1
+        assert "Could not infer schema" in result.output
+        assert "Traceback" not in result.output
+
+    def test_schema_sample_message_is_honest(self, tmp_path):
+        """Footer reports the sample cap, not '{sample}+ rows'."""
+        import json as _json
+
+        f = tmp_path / "rows.json"
+        f.write_text(_json.dumps([{"a": 1}, {"a": 2}]))
+        result = runner.invoke(cli, ["schema", str(f), "--sample", "100"])
+        assert result.exit_code == 0
+        assert "up to 100 rows" in result.output