fix(python): Fix duplicate model docstrings on regeneration

.chronus/changes/python-docstring-duplicate-fix-2026-7-16-22-38-0.md

@@ -0,0 +1,8 @@
+---
+# Change versionKind to one of: internal, fix, dependencies, feature, deprecation, breaking
+changeKind: fix
+packages:
+  - "@typespec/http-client-python"
+---
+
+[Python] Fix duplicate `:keyword:`/`:paramtype:` lines in generated DPG model docstrings that duplicated the existing `:ivar:`/`:vartype:` entries

packages/http-client-python/generator/pygen/codegen/serializers/model_serializer.py

@@ -122,15 +122,6 @@ def input_documentation_string(prop: Property) -> list[str]:
         # building the param line of the property doc
         return _documentation_string(prop, "keyword", "paramtype")
 
-    def keyword_documentation_string(self, model: ModelType) -> list[str]:
-        # building the ``:keyword:``/``:paramtype:`` lines for the keyword-only
-        # arguments of the generated ``__init__`` overload so that the docstring
-        # keeps a 1:1 correlation with the keyword-only arguments in the signature.
-        retval: list[str] = []
-        for prop in sorted(self._init_line_parameters(model), key=lambda x: x.optional):
-            retval.extend(self.input_documentation_string(prop))
-        return retval
-
     @staticmethod
     def variable_documentation_string(prop: Property) -> list[str]:
         return _documentation_string(prop, "ivar", "vartype")
@@ -428,6 +419,16 @@ def declare_model(self, model: ModelType) -> str:
             basename += f", discriminator='{model.discriminator_value}'"
         return f"class {model.name}({basename}):{self.class_pylint_disable(model)}"
 
+    def class_pylint_disable(self, model: ModelType) -> str:
+        retval = super().class_pylint_disable(model)
+        # DPG models render an empty ``@overload def __init__(self, *, ...)`` body, so the
+        # guideline checker validates the keyword-only arguments against the *class* docstring.
+        # We only document those arguments as instance variables (``:ivar:``) to avoid a redundant
+        # ``:keyword:`` entry per property, so silence the keyword/keyword-only correlation check.
+        if self._init_line_parameters(model):
+            retval = add_to_pylint_disable(retval, "docstring-keyword-should-match-keyword-only")
+        return retval
+
     @staticmethod
     def get_properties_to_declare(model: ModelType) -> list[Property]:
         if model.parents:

packages/http-client-python/generator/pygen/codegen/templates/model_dpg.py.jinja2

@@ -16,11 +16,6 @@
             {% endfor %}
         {% endfor %}
     {% endif %}
-    {% if serializer.need_init(model) %}
-        {% for line in serializer.keyword_documentation_string(model) %}
-    {{ macros.wrap_model_string(line, '\n    ') -}}
-        {% endfor %}
-    {% endif %}
     """
 
     {% if model.is_polymorphic %}