remove conversion of cron to identifier; add doc clarification

Author: themisvaltinos

docs/concepts/models/python_models.md

@@ -394,6 +394,35 @@ It's also possible to use the `@EACH` macro, combined with a global list variabl
 ...
 ```
 
+## Using macros in model properties
+
+Python models support macro variables in model properties. However, special care must be taken when the macro variable appears within a string.
+
+For example when using macro variables inside cron expressions, you need to wrap the entire expression in quotes and prefix it with `@` to ensure proper parsing:
+
+```python linenums="1"
+# Correct: Wrap the cron expression containing a macro variable
+@model(
+    "my_model",
+    cron="@'*/@{mins} * * * *'",  # Note the @'...' syntax
+    ...
+)
+
+# This also works with blueprint variables
+@model(
+    "@{customer}.scheduled_model",
+    cron="@'0 @{hour} * * *'",
+    blueprints=[
+        {"customer": "customer_1", "hour": 2}, # Runs at 2 AM
+        {"customer": "customer_2", "hour": 8}, # Runs at 8 AM
+    ],
+    ...
+)
+
+```
+
+This is necessary because cron expressions often use `@` for aliases (like `@daily`, `@hourly`), which can conflict with SQLMesh's macro syntax.
+
 ## Examples
 ### Basic
 The following is an example of a Python model returning a static Pandas DataFrame.

sqlmesh/core/model/definition.py

@@ -2786,10 +2786,6 @@ def render_field_value(value: t.Any) -> t.Any:
         ) or field_value is None:
             continue
 
-        # If it contains a macro reference we need to render it similar to sql models
-        if field == "cron" and isinstance(field_value, str):
-            field_value = exp.to_identifier(field_value)
-
         if field in RUNTIME_RENDERED_MODEL_FIELDS:
             fields[field] = parse_strings_with_macro_refs(field_value, dialect)
             continue

tests/core/test_model.py

@@ -10772,7 +10772,7 @@ def test_python_model_cron_with_blueprints(tmp_path: Path) -> None:
 @model(
     "@{customer}.some_table",
     kind="FULL",
-    cron="*/@{min} * * * *",
+    cron="@'*/@{min} * * * *'",
     blueprints=[
         {"customer": "customer1", "field_a": "x", "field_b": "y", "min": 5},
         {"customer": "customer2", "field_a": "z", "field_b": "w", "min": 10},