fix: extract parameter defaults independently for each template in code change detection

Use each template's own Parameters section to extract defaults,
so expansion produces correct results even if parameter definitions
changed between the current and deployed template versions.

Author: bnusunny

samcli/lib/sync/infra_sync_executor.py

@@ -586,18 +586,24 @@ def _detect_foreach_code_changes(
         from samcli.lib.cfn_language_extensions.sam_integration import expand_language_extensions
 
         try:
-            # Extract parameter default values from the template so Ref-based
-            # ForEach collections (e.g. {"Ref": "ServiceNames"}) can be resolved.
-            param_values = {}
+            # Extract parameter default values from each template independently
+            # so Ref-based ForEach collections can be resolved correctly even if
+            # parameter definitions changed between deployments.
+            current_params = {}
             for param_name, param_def in current_template.get("Parameters", {}).items():
                 if isinstance(param_def, dict) and "Default" in param_def:
-                    param_values[param_name] = param_def["Default"]
+                    current_params[param_name] = param_def["Default"]
+
+            deployed_params = {}
+            for param_name, param_def in last_deployed_template.get("Parameters", {}).items():
+                if isinstance(param_def, dict) and "Default" in param_def:
+                    deployed_params[param_name] = param_def["Default"]
 
             current_expanded = expand_language_extensions(
-                current_template, parameter_values=param_values
+                current_template, parameter_values=current_params
             ).expanded_template
             deployed_expanded = expand_language_extensions(
-                last_deployed_template, parameter_values=param_values
+                last_deployed_template, parameter_values=deployed_params
             ).expanded_template
         except Exception as e:
             LOG.warning(