Report enum variable validation errors cleanly

structkit/commands/generate.py

@@ -4,7 +4,7 @@
 import argparse
 from structkit.file_item import FileItem
 from structkit.completers import file_strategy_completer, structures_completer
-from structkit.template_renderer import TemplateRenderer
+from structkit.template_renderer import TemplateRenderer, TemplateVariableError
 from structkit.sources import SourceError, resolve_structures_path
 
 import subprocess
@@ -186,7 +186,11 @@ def execute(self, args):
       return
 
     # Actually generate structure
-    self._create_structure(args, mappings)
+    try:
+      self._create_structure(args, mappings)
+    except TemplateVariableError as exc:
+      self.logger.error(f"❗ {exc}")
+      raise SystemExit(1) from None
 
     # Run post-hooks
     if not self._run_hooks(post_hooks, hook_type="post"):

structkit/template_renderer.py

@@ -19,6 +19,10 @@
 from structkit.utils import get_current_repo
 
 
+class TemplateVariableError(ValueError):
+    """Raised when a template variable is missing or fails validation."""
+
+
 class TemplateRenderer:
     def __init__(self, config_variables, input_store, non_interactive, mappings=None):
       self.config_variables = config_variables
@@ -147,8 +151,15 @@ def prompt_for_missing_vars(self, content, vars):
       self.logger.debug(f"Default values from config: {default_values}")
 
       for var in undeclared_variables:
+        conf = schema.get(var, {})
+        if var in vars:
+          if conf:
+            coerced = self._coerce_and_validate(var, vars[var], conf)
+            self.input_store.set_value(var, coerced)
+            vars[var] = coerced
+          continue
+
         if var not in vars:
-          conf = schema.get(var, {})
           required = conf.get('required', False)
           default = self.input_data.get(var, default_values.get(var, ""))
           if self.non_interactive:
@@ -190,7 +201,7 @@ def prompt_for_missing_vars(self, content, vars):
                 user_input = raw
               else:
                 # For invalid enum input, raise immediately instead of re-prompting
-                raise ValueError(f"Variable '{var}' must be one of {enum}, got: {raw}")
+                raise self._enum_value_error(var, raw, enum)
             else:
               if description:
                 print(f"{icon} {BOLD}{var}{RESET}: {description}")
@@ -223,12 +234,12 @@ def _coerce_and_validate(self, name, value, conf):
         else:
           coerced = '' if value is None else str(value)
       except Exception:
-        raise ValueError(f"Variable '{name}' could not be coerced to {vtype} (value: {original})")
+        raise TemplateVariableError(f"Variable '{name}' could not be coerced to {vtype} (value: {original})")
 
       # Enum validation
       enum = conf.get('enum')
       if enum is not None and coerced not in enum:
-        raise ValueError(f"Variable '{name}' must be one of {enum}, got: {coerced}")
+        raise self._enum_value_error(name, coerced, enum)
 
       # Regex validation (only for strings)
       pattern = conf.get('regex') or conf.get('pattern')
@@ -255,3 +266,14 @@ def _as_num(x):
           raise ValueError(f"Variable '{name}' must be <= {maxv}, got {coerced}")
 
       return coerced
+
+    def _enum_value_error(self, name, value, enum):
+      allowed_values = ", ".join(str(item) for item in enum)
+      if value is None or value == "":
+        return TemplateVariableError(
+          f"Variable '{name}' must be set to one of: {allowed_values}. "
+          f"No value was provided. Pass --vars {name}=<value> or define a default."
+        )
+      return TemplateVariableError(
+        f"Variable '{name}' must be one of: {allowed_values}. Got: {value}."
+      )

tests/test_commands_more.py

@@ -9,6 +9,7 @@
 from structkit.commands.list import ListCommand
 from structkit.commands.mcp import MCPCommand
 from structkit.commands.validate import ValidateCommand
+from structkit.template_renderer import TemplateVariableError
 
 
 @pytest.fixture
@@ -114,6 +115,25 @@ def test_generate_mappings_file_not_found(parser, tmp_path):
         command.execute(args)
 
 
+def test_generate_reports_template_variable_error_without_traceback(parser, tmp_path, caplog):
+    command = GenerateCommand(parser)
+    args = parser.parse_args(['struct-x', str(tmp_path)])
+    args.structures_path = None
+    args.mappings_file = None
+    args.backup = None
+
+    with patch.object(command, '_load_yaml_config', return_value={'files': [], 'folders': []}), \
+         patch.object(command, '_create_structure', side_effect=TemplateVariableError(
+             "Variable 'environment' must be one of: dev, staging, prod. Got: qa."
+         )):
+        with pytest.raises(SystemExit) as excinfo:
+            command.execute(args)
+
+    assert excinfo.value.code == 1
+    assert "Variable 'environment' must be one of: dev, staging, prod. Got: qa." in caplog.text
+    assert "Traceback" not in caplog.text
+
+
 def test_info_nonexistent_file_logs_error(parser):
     command = InfoCommand(parser)
     args = parser.parse_args(['does-not-exist'])

tests/test_template_renderer.py

@@ -1,6 +1,6 @@
 import pytest
 from unittest.mock import patch, MagicMock
-from structkit.template_renderer import TemplateRenderer
+from structkit.template_renderer import TemplateRenderer, TemplateVariableError
 
 @pytest.fixture
 def renderer():
@@ -204,3 +204,45 @@ def test_variable_icon_selection():
     assert renderer._get_variable_icon("version", "string") == "🏷️"
     assert renderer._get_variable_icon("config_path", "string") == "📁"
     assert renderer._get_variable_icon("random_var", "string") == "🔧"
+
+
+def test_enum_missing_value_has_clean_error(tmp_path):
+    config_variables = [
+        {"environment": {
+            "type": "string",
+            "description": "Target deployment environment",
+            "enum": ["dev", "staging", "prod"],
+        }}
+    ]
+    renderer = TemplateRenderer(
+        config_variables,
+        str(tmp_path / "input.json"),
+        non_interactive=True,
+    )
+
+    with pytest.raises(TemplateVariableError) as excinfo:
+        renderer.prompt_for_missing_vars("{{@ environment @}}", {})
+
+    message = str(excinfo.value)
+    assert "Variable 'environment' must be set to one of: dev, staging, prod" in message
+    assert "No value was provided" in message
+    assert "--vars environment=<value>" in message
+
+
+def test_enum_invalid_value_has_clean_error(tmp_path):
+    config_variables = [
+        {"environment": {
+            "type": "string",
+            "enum": ["dev", "staging", "prod"],
+        }}
+    ]
+    renderer = TemplateRenderer(
+        config_variables,
+        str(tmp_path / "input.json"),
+        non_interactive=True,
+    )
+
+    with pytest.raises(TemplateVariableError) as excinfo:
+        renderer.prompt_for_missing_vars("{{@ environment @}}", {"environment": "qa"})
+
+    assert str(excinfo.value) == "Variable 'environment' must be one of: dev, staging, prod. Got: qa."