fix(workflows): validate non-string step types (#4111)

Return an actionable validation error when a workflow step type is a YAML list or mapping instead of raising during registry membership checks.

Assisted-by: OpenAI Codex (model: GPT-5, autonomous)

src/specify_cli/workflows/engine.py

@@ -366,6 +366,17 @@ def _validate_steps(
 
         # Determine step type
         step_type = step_config.get("type", "command")
+        if not isinstance(step_type, str):
+            # Registry keys are strings. Checking an unhashable YAML value
+            # (for example ``type: [shell]`` or a mapping) against the set
+            # below raises a raw TypeError before validation can report the
+            # authoring mistake. Guard every non-string shape first, matching
+            # the typed validation already applied to workflow and step IDs.
+            errors.append(
+                f"Step {step_id!r}: 'type' must be a string, got "
+                f"{type(step_type).__name__} ({step_type!r})."
+            )
+            continue
         if step_type not in _get_valid_step_types():
             errors.append(
                 f"Step {step_id!r} has invalid type {step_type!r}."

tests/test_workflows.py

@@ -4565,6 +4565,29 @@ steps:
         errors = validate_workflow(definition)
         assert any("invalid type" in e.lower() for e in errors)
 
+    @pytest.mark.parametrize("step_type", [["shell"], {"name": "shell"}])
+    def test_non_string_step_type_reports_error(self, step_type):
+        """Unhashable YAML values must not crash registry membership checks."""
+        from specify_cli.workflows.engine import WorkflowDefinition, validate_workflow
+
+        definition = WorkflowDefinition(
+            {
+                "workflow": {
+                    "id": "test",
+                    "name": "Test",
+                    "version": "1.0.0",
+                },
+                "steps": [{"id": "bad", "type": step_type}],
+            }
+        )
+
+        errors = validate_workflow(definition)
+
+        assert errors == [
+            f"Step 'bad': 'type' must be a string, got "
+            f"{type(step_type).__name__} ({step_type!r})."
+        ]
+
     def test_nested_step_validation(self):
         from specify_cli.workflows.engine import WorkflowDefinition, validate_workflow