Refactor _rewrite_inner_scalar function for improved step reference handling (#2352)

- Adjust the order of replacement steps to ensure child step renames occur before parameter bindings, preserving parent step references in bindings.
- Update unit tests to reflect the new order and add a test for preserving parent step references in parameter bindings.

Author: dkosowski87

inference/core/workflows/execution_engine/v1/inner_workflow/inline.py

@@ -256,11 +256,13 @@ def _rewrite_inner_scalar(
 
     Non-strings are returned unchanged. For strings, replacements run in order:
 
-    1. ``_replace_inputs_in_string`` — workflow inputs and defaults.
-    2. If that step produced a non-string (whole ``$inputs.*`` reference), it is returned as-is;
-       dotted step references are not applied to non-strings.
-    3. ``_replace_step_prefixes_in_string`` — ``$steps.<child>.`` → ``$steps.<new>.``.
-    4. ``_replace_bare_child_step_refs_in_string`` — bare ``$steps.<child>`` tokens.
+    1. ``_replace_step_prefixes_in_string`` — ``$steps.<child>.`` → ``$steps.<new>.``.
+    2. ``_replace_bare_child_step_refs_in_string`` — bare ``$steps.<child>`` tokens.
+    3. ``_replace_inputs_in_string`` — workflow inputs and defaults (parent selectors).
+
+    Child step renames run before parameter bindings so a binding such as
+    ``$steps.dynamic_crop.crops`` that refers to a parent step is not rewritten when the
+    child workflow also defines a step named ``dynamic_crop``.
 
     ``step_pairs`` maps each original child step name to its unique name after inlining
     (typically ``f"{inner_name}__{child_step}"``).
@@ -293,26 +295,21 @@ def _rewrite_inner_scalar(
     if not isinstance(value, str):
         return value
 
-    after_inputs = _replace_inputs_in_string(
-        value,
-        bindings=bindings,
-        input_defaults=input_defaults,
-    )
-
-    if not isinstance(after_inputs, str):
-        return after_inputs
-
     dotted = _replace_step_prefixes_in_string(
-        after_inputs,
+        value,
         old_to_new=step_pairs,
     )
 
-    out = _replace_bare_child_step_refs_in_string(
+    after_bare = _replace_bare_child_step_refs_in_string(
         dotted,
         step_pairs=step_pairs,
     )
 
-    return out
+    return _replace_inputs_in_string(
+        after_bare,
+        bindings=bindings,
+        input_defaults=input_defaults,
+    )
 
 
 def _deep_map_leaves(obj: Any, fn: Callable[[Any], Any]) -> Any:

tests/workflows/unit_tests/execution_engine/inner_workflow/test_inline.py

@@ -221,7 +221,7 @@ def test_rewrite_inner_scalar_non_string_unchanged() -> None:
     ) == {"nested": True}
 
 
-def test_rewrite_inner_scalar_pipeline_inputs_then_dotted_then_bare() -> None:
+def test_rewrite_inner_scalar_pipeline_dotted_then_bare_then_inputs() -> None:
     out = _rewrite_inner_scalar(
         "$inputs.msg and $steps.echo.out and $steps.echo",
         step_pairs=[("echo", "inner__echo")],
@@ -231,6 +231,17 @@ def test_rewrite_inner_scalar_pipeline_inputs_then_dotted_then_bare() -> None:
     assert out == "hello and $steps.inner__echo.out and $steps.inner__echo"
 
 
+def test_rewrite_inner_scalar_preserves_parent_step_in_parameter_binding() -> None:
+    """Parent ``$steps.<name>`` in bindings must not be renamed to the inlined child step."""
+    out = _rewrite_inner_scalar(
+        "$inputs.vehicle_image",
+        step_pairs=[("dynamic_crop", "inner__dynamic_crop")],
+        bindings={"vehicle_image": "$steps.dynamic_crop.crops"},
+        input_defaults={},
+    )
+    assert out == "$steps.dynamic_crop.crops"
+
+
 def test_rewrite_inner_scalar_whole_input_non_string_skips_step_rewrite() -> None:
     sentinel = {"selector": "$steps.echo.x"}
     out = _rewrite_inner_scalar(