From f9b7c14c3deac6ea00069a2961ee6de704835a91 Mon Sep 17 00:00:00 2001
From: iscai-msft <isabellavcai@gmail.com>
Date: Mon, 27 Apr 2026 13:33:17 -0400
Subject: [PATCH 1/6] fix: convert custom etag-typed headers to
 etag/match_condition

Custom headers typed as Azure.Core.eTag (e.g. x-ms-blob-if-match,
x-ms-source-if-match) now get the same etag/match_condition treatment
as standard If-Match/If-None-Match headers. The original wire name is
preserved via originalWireName so the correct HTTP header is sent.

- Add isEtag flag in emitter for Azure.Core.eTag-typed headers
- Add _is_etag_match/_is_etag_none_match helpers in preprocessor
- Preserve originalWireName in headers_convert for custom headers
- Use originalWireName in serializer for dynamic header name
- Use identity-based removal for etag param reordering

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
---
 ...-etagMatchCondition-2026-04-27-13-33-08.md |  7 +++
 .../http-client-python/emitter/src/http.ts    | 15 +++++-
 .../pygen/codegen/models/parameter.py         |  1 +
 .../serializers/parameter_serializer.py       | 33 +++++++++----
 .../generator/pygen/preprocess/__init__.py    | 47 ++++++++++++++++---
 5 files changed, 85 insertions(+), 18 deletions(-)
 create mode 100644 .chronus/changes/python-etagMatchCondition-2026-04-27-13-33-08.md

diff --git a/.chronus/changes/python-etagMatchCondition-2026-04-27-13-33-08.md b/.chronus/changes/python-etagMatchCondition-2026-04-27-13-33-08.md
new file mode 100644
index 00000000000..be12b4f1143
--- /dev/null
+++ b/.chronus/changes/python-etagMatchCondition-2026-04-27-13-33-08.md
@@ -0,0 +1,7 @@
+---
+changeKind: fix
+packages:
+  - "@typespec/http-client-python"
+---
+
+Convert custom etag-typed headers (e.g. `x-ms-blob-if-match`) to `etag`/`match_condition` parameters, matching the standard `If-Match`/`If-None-Match` behavior while preserving the original wire name for the HTTP header
diff --git a/packages/http-client-python/emitter/src/http.ts b/packages/http-client-python/emitter/src/http.ts
index e87e8b1f113..98e24398298 100644
--- a/packages/http-client-python/emitter/src/http.ts
+++ b/packages/http-client-python/emitter/src/http.ts
@@ -1,4 +1,4 @@
-import { NoTarget } from "@typespec/compiler";
+import { getNamespaceFullName, NoTarget } from "@typespec/compiler";
 
 import {
   getHttpOperationParameter,
@@ -19,6 +19,7 @@ import {
   SdkQueryParameter,
   SdkServiceMethod,
   SdkServiceResponseHeader,
+  SdkType,
   UsageFlags,
 } from "@azure-tools/typespec-client-generator-core";
 import { HttpStatusCodeRange } from "@typespec/http";
@@ -41,6 +42,17 @@ export enum ReferredByOperationTypes {
   NonPagingOnly = 2,
 }
 
+function isEtagType(type: SdkType): boolean {
+  if (type.kind === "nullable") return isEtagType(type.type);
+  const raw = type.__raw;
+  if (!raw || raw.kind !== "Scalar") return false;
+  return (
+    raw.name === "eTag" &&
+    raw.namespace !== undefined &&
+    getNamespaceFullName(raw.namespace) === "Azure.Core"
+  );
+}
+
 function isContentTypeParameter(parameter: SdkHeaderParameter) {
   return parameter.serializedName.toLowerCase() === "content-type";
 }
@@ -496,6 +508,7 @@ function emitHttpHeaderParameter(
     delimiter,
     explode,
     clientDefaultValue,
+    isEtag: isEtagType(parameter.type),
   };
 }
 
diff --git a/packages/http-client-python/generator/pygen/codegen/models/parameter.py b/packages/http-client-python/generator/pygen/codegen/models/parameter.py
index 26eb0ba5c9a..3bc9d7d2f49 100644
--- a/packages/http-client-python/generator/pygen/codegen/models/parameter.py
+++ b/packages/http-client-python/generator/pygen/codegen/models/parameter.py
@@ -61,6 +61,7 @@ def __init__(
     ) -> None:
         super().__init__(yaml_data, code_model)
         self.wire_name: str = yaml_data.get("wireName", "")
+        self.original_wire_name: str = yaml_data.get("originalWireName", self.wire_name)
         self.client_name: str = self.yaml_data["clientName"]
         self.optional: bool = self.yaml_data["optional"]
         self.implementation: Optional[str] = yaml_data.get("implementation", None)
diff --git a/packages/http-client-python/generator/pygen/codegen/serializers/parameter_serializer.py b/packages/http-client-python/generator/pygen/codegen/serializers/parameter_serializer.py
index 9091f86748d..9b37025ff3f 100644
--- a/packages/http-client-python/generator/pygen/codegen/serializers/parameter_serializer.py
+++ b/packages/http-client-python/generator/pygen/codegen/serializers/parameter_serializer.py
@@ -39,16 +39,6 @@ class PopKwargType(Enum):
     "client-request-id": [],
     "x-ms-client-request-id": [],
     "return-client-request-id": [],
-    "etag": [
-        """if_match = prep_if_match(etag, match_condition)""",
-        """if if_match is not None:""",
-        """    _headers["If-Match"] = _SERIALIZER.header("if_match", if_match, "str")""",
-    ],
-    "match-condition": [
-        """if_none_match = prep_if_none_match(etag, match_condition)""",
-        """if if_none_match is not None:""",
-        """    _headers["If-None-Match"] = _SERIALIZER.header("if_none_match", if_none_match, "str")""",
-    ],
 }
 
 
@@ -157,6 +147,29 @@ def serialize_query_header(
         ):
             return SPECIAL_HEADER_SERIALIZATION[param.wire_name.lower()]
 
+        if (
+            not is_legacy
+            and param.location == ParameterLocation.HEADER
+            and param.wire_name.lower() in ("etag", "match-condition")
+        ):
+            # Build etag serialization using the original wire name for the
+            # actual HTTP header.  For standard If-Match / If-None-Match the
+            # original wire name equals those values; for custom etag headers
+            # (e.g. x-ms-blob-if-match) it carries the real header name.
+            header_name = param.original_wire_name
+            if param.wire_name.lower() == "etag":
+                return [
+                    """if_match = prep_if_match(etag, match_condition)""",
+                    """if if_match is not None:""",
+                    f"""    _headers["{header_name}"] = _SERIALIZER.header("if_match", if_match, "str")""",
+                ]
+            else:
+                return [
+                    """if_none_match = prep_if_none_match(etag, match_condition)""",
+                    """if if_none_match is not None:""",
+                    f"""    _headers["{header_name}"] = _SERIALIZER.header("if_none_match", if_none_match, "str")""",
+                ]
+
         set_parameter = "_{}['{}'] = {}".format(
             kwarg_name,
             param.wire_name,
diff --git a/packages/http-client-python/generator/pygen/preprocess/__init__.py b/packages/http-client-python/generator/pygen/preprocess/__init__.py
index 6d3344059a3..6306449dadc 100644
--- a/packages/http-client-python/generator/pygen/preprocess/__init__.py
+++ b/packages/http-client-python/generator/pygen/preprocess/__init__.py
@@ -166,8 +166,29 @@ def get_wire_name_lower(parameter: dict[str, Any]) -> str:
     return (parameter.get("wireName") or "").lower()
 
 
+def _is_etag_match(parameter: dict[str, Any]) -> bool:
+    """Return True if this header should fill the if-match etag slot."""
+    wire = get_wire_name_lower(parameter)
+    if wire == "if-match":
+        return True
+    return bool(parameter.get("isEtag")) and "none-match" not in wire
+
+
+def _is_etag_none_match(parameter: dict[str, Any]) -> bool:
+    """Return True if this header should fill the if-none-match etag slot."""
+    wire = get_wire_name_lower(parameter)
+    if wire == "if-none-match":
+        return True
+    return bool(parameter.get("isEtag")) and "none-match" in wire
+
+
 def headers_convert(yaml_data: dict[str, Any], replace_data: Any) -> None:
     if isinstance(replace_data, dict):
+        # Preserve original wire name so the serializer can use it
+        # for the actual HTTP header (important for custom etag headers
+        # like x-ms-blob-if-match).
+        if "wireName" in replace_data and "wireName" in yaml_data:
+            yaml_data["originalWireName"] = yaml_data["wireName"]
         for k, v in replace_data.items():
             yaml_data[k] = v
 
@@ -317,9 +338,9 @@ def update_client(self, yaml_data: dict[str, Any]) -> None:
                     if p["location"] == "header" and wire_name_lower == "client-request-id":
                         yaml_data["requestIdHeaderName"] = wire_name_lower
                     if self.version_tolerant and p["location"] == "header":
-                        if wire_name_lower == "if-match":
+                        if _is_etag_match(p) and not property_if_match:
                             property_if_match = p
-                        elif wire_name_lower == "if-none-match":
+                        elif _is_etag_none_match(p) and not property_if_none_match:
                             property_if_none_match = p
                 # pylint: disable=line-too-long
                 # some service(e.g. https://github.com/Azure/azure-rest-api-specs/blob/main/specification/cosmos-db/data-plane/Microsoft.Tables/preview/2019-02-02/table.json)
@@ -333,11 +354,11 @@ def update_client(self, yaml_data: dict[str, Any]) -> None:
 
                 if property_if_match and property_if_none_match:
                     # arrange if-match and if-none-match to the end of parameters
-                    o["parameters"] = [
-                        item
-                        for item in o["parameters"]
-                        if get_wire_name_lower(item) not in ("if-match", "if-none-match")
-                    ] + [property_if_match, property_if_none_match]
+                    etag_params = {id(property_if_match), id(property_if_none_match)}
+                    o["parameters"] = [item for item in o["parameters"] if id(item) not in etag_params] + [
+                        property_if_match,
+                        property_if_none_match,
+                    ]
 
                     o["hasEtag"] = True
                     yaml_data["hasEtag"] = True
@@ -374,6 +395,18 @@ def update_parameter(self, yaml_data: dict[str, Any]) -> None:
             yaml_data["hideInMethod"] = True
         if self.version_tolerant and yaml_data["location"] == "header" and wire_name_lower in HEADERS_CONVERT_IN_METHOD:
             headers_convert(yaml_data, HEADERS_CONVERT_IN_METHOD[wire_name_lower])
+        elif (
+            self.version_tolerant
+            and yaml_data["location"] == "header"
+            and yaml_data.get("isEtag")
+            and wire_name_lower not in HEADERS_CONVERT_IN_METHOD
+        ):
+            # Custom etag-typed headers (e.g. x-ms-blob-if-match) get the same
+            # etag/match_condition treatment as standard If-Match/If-None-Match.
+            if _is_etag_none_match(yaml_data):
+                headers_convert(yaml_data, HEADERS_CONVERT_IN_METHOD["if-none-match"])
+            else:
+                headers_convert(yaml_data, HEADERS_CONVERT_IN_METHOD["if-match"])
         if wire_name_lower in ["$host", "content-type", "accept"] and yaml_data["type"]["type"] == "constant":
             yaml_data["clientDefaultValue"] = yaml_data["type"]["value"]
 

From c1fdbb4bc5d0ed885ad6f639fd81518a4d8da228 Mon Sep 17 00:00:00 2001
From: iscai-msft <isabellavcai@gmail.com>
Date: Mon, 27 Apr 2026 14:10:54 -0400
Subject: [PATCH 2/6] simplify check

---
 .../http-client-python/emitter/src/http.ts    | 14 +++-
 .../pygen/codegen/models/parameter.py         |  2 +-
 .../serializers/parameter_serializer.py       | 25 ++----
 .../generator/pygen/preprocess/__init__.py    | 84 ++++++++-----------
 4 files changed, 57 insertions(+), 68 deletions(-)

diff --git a/packages/http-client-python/emitter/src/http.ts b/packages/http-client-python/emitter/src/http.ts
index 98e24398298..0a695e68c6e 100644
--- a/packages/http-client-python/emitter/src/http.ts
+++ b/packages/http-client-python/emitter/src/http.ts
@@ -53,6 +53,18 @@ function isEtagType(type: SdkType): boolean {
   );
 }
 
+function getEtagRole(parameter: SdkHeaderParameter): string | undefined {
+  if (!isEtagType(parameter.type)) return undefined;
+  const name = parameter.name.toLowerCase();
+  const wire = parameter.serializedName.toLowerCase();
+  // Check client name first, then wire name
+  if (name.includes("nonematch") || name.includes("none_match")) return "ifNoneMatch";
+  if (name.includes("match")) return "ifMatch";
+  if (wire.endsWith("if-none-match") || wire === "if-none-match") return "ifNoneMatch";
+  if (wire.endsWith("if-match") || wire === "if-match") return "ifMatch";
+  return undefined;
+}
+
 function isContentTypeParameter(parameter: SdkHeaderParameter) {
   return parameter.serializedName.toLowerCase() === "content-type";
 }
@@ -508,7 +520,7 @@ function emitHttpHeaderParameter(
     delimiter,
     explode,
     clientDefaultValue,
-    isEtag: isEtagType(parameter.type),
+    etagRole: getEtagRole(parameter),
   };
 }
 
diff --git a/packages/http-client-python/generator/pygen/codegen/models/parameter.py b/packages/http-client-python/generator/pygen/codegen/models/parameter.py
index 3bc9d7d2f49..726756671ff 100644
--- a/packages/http-client-python/generator/pygen/codegen/models/parameter.py
+++ b/packages/http-client-python/generator/pygen/codegen/models/parameter.py
@@ -61,7 +61,7 @@ def __init__(
     ) -> None:
         super().__init__(yaml_data, code_model)
         self.wire_name: str = yaml_data.get("wireName", "")
-        self.original_wire_name: str = yaml_data.get("originalWireName", self.wire_name)
+        self.etag_role: Optional[str] = yaml_data.get("etagRole", None)
         self.client_name: str = self.yaml_data["clientName"]
         self.optional: bool = self.yaml_data["optional"]
         self.implementation: Optional[str] = yaml_data.get("implementation", None)
diff --git a/packages/http-client-python/generator/pygen/codegen/serializers/parameter_serializer.py b/packages/http-client-python/generator/pygen/codegen/serializers/parameter_serializer.py
index 9b37025ff3f..9cfbdc94a16 100644
--- a/packages/http-client-python/generator/pygen/codegen/serializers/parameter_serializer.py
+++ b/packages/http-client-python/generator/pygen/codegen/serializers/parameter_serializer.py
@@ -147,28 +147,19 @@ def serialize_query_header(
         ):
             return SPECIAL_HEADER_SERIALIZATION[param.wire_name.lower()]
 
-        if (
-            not is_legacy
-            and param.location == ParameterLocation.HEADER
-            and param.wire_name.lower() in ("etag", "match-condition")
-        ):
-            # Build etag serialization using the original wire name for the
-            # actual HTTP header.  For standard If-Match / If-None-Match the
-            # original wire name equals those values; for custom etag headers
-            # (e.g. x-ms-blob-if-match) it carries the real header name.
-            header_name = param.original_wire_name
-            if param.wire_name.lower() == "etag":
+        if not is_legacy and param.location == ParameterLocation.HEADER and param.etag_role is not None:
+            header_name = param.wire_name
+            if param.etag_role == "ifMatch":
                 return [
                     """if_match = prep_if_match(etag, match_condition)""",
                     """if if_match is not None:""",
                     f"""    _headers["{header_name}"] = _SERIALIZER.header("if_match", if_match, "str")""",
                 ]
-            else:
-                return [
-                    """if_none_match = prep_if_none_match(etag, match_condition)""",
-                    """if if_none_match is not None:""",
-                    f"""    _headers["{header_name}"] = _SERIALIZER.header("if_none_match", if_none_match, "str")""",
-                ]
+            return [
+                """if_none_match = prep_if_none_match(etag, match_condition)""",
+                """if if_none_match is not None:""",
+                f"""    _headers["{header_name}"] = _SERIALIZER.header("if_none_match", if_none_match, "str")""",
+            ]
 
         set_parameter = "_{}['{}'] = {}".format(
             kwarg_name,
diff --git a/packages/http-client-python/generator/pygen/preprocess/__init__.py b/packages/http-client-python/generator/pygen/preprocess/__init__.py
index 6306449dadc..4c7a4263d4b 100644
--- a/packages/http-client-python/generator/pygen/preprocess/__init__.py
+++ b/packages/http-client-python/generator/pygen/preprocess/__init__.py
@@ -132,20 +132,18 @@ def update_paging_response(yaml_data: dict[str, Any]) -> None:
     "client-request-id",
     "return-client-request-id",
 )
-HEADERS_CONVERT_IN_METHOD = {
-    "if-match": {
-        "clientName": "etag",
-        "wireName": "etag",
-        "description": "check if resource is changed. Set None to skip checking etag.",
-    },
-    "if-none-match": {
-        "clientName": "match_condition",
-        "wireName": "match-condition",
-        "description": "The match condition to use upon the etag.",
-        "type": {
-            "type": "sdkcore",
-            "name": "MatchConditions",
-        },
+ETAG_MATCH_DATA = {
+    "clientName": "etag",
+    "etagRole": "ifMatch",
+    "description": "check if resource is changed. Set None to skip checking etag.",
+}
+ETAG_NONE_MATCH_DATA = {
+    "clientName": "match_condition",
+    "etagRole": "ifNoneMatch",
+    "description": "The match condition to use upon the etag.",
+    "type": {
+        "type": "sdkcore",
+        "name": "MatchConditions",
     },
 }
 CLOUD_SETTING = {
@@ -166,29 +164,25 @@ def get_wire_name_lower(parameter: dict[str, Any]) -> str:
     return (parameter.get("wireName") or "").lower()
 
 
-def _is_etag_match(parameter: dict[str, Any]) -> bool:
-    """Return True if this header should fill the if-match etag slot."""
-    wire = get_wire_name_lower(parameter)
-    if wire == "if-match":
-        return True
-    return bool(parameter.get("isEtag")) and "none-match" not in wire
-
+def _get_etag_role(parameter: dict[str, Any]) -> Optional[str]:
+    """Return 'ifMatch', 'ifNoneMatch', or None for this header parameter.
 
-def _is_etag_none_match(parameter: dict[str, Any]) -> bool:
-    """Return True if this header should fill the if-none-match etag slot."""
+    The emitter sets etagRole directly for TypeSpec inputs. For autorest/swagger
+    inputs we fall back to the wire name.
+    """
+    role = parameter.get("etagRole")
+    if role:
+        return role
     wire = get_wire_name_lower(parameter)
+    if wire == "if-match":
+        return "ifMatch"
     if wire == "if-none-match":
-        return True
-    return bool(parameter.get("isEtag")) and "none-match" in wire
+        return "ifNoneMatch"
+    return None
 
 
 def headers_convert(yaml_data: dict[str, Any], replace_data: Any) -> None:
     if isinstance(replace_data, dict):
-        # Preserve original wire name so the serializer can use it
-        # for the actual HTTP header (important for custom etag headers
-        # like x-ms-blob-if-match).
-        if "wireName" in replace_data and "wireName" in yaml_data:
-            yaml_data["originalWireName"] = yaml_data["wireName"]
         for k, v in replace_data.items():
             yaml_data[k] = v
 
@@ -302,9 +296,8 @@ def update_types(self, yaml_data: list[dict[str, Any]]) -> None:
                         value["name"] = upper_name
 
         # add type for reference
-        for v in HEADERS_CONVERT_IN_METHOD.values():
-            if isinstance(v, dict) and "type" in v:
-                yaml_data.append(v["type"])
+        if "type" in ETAG_NONE_MATCH_DATA:
+            yaml_data.append(ETAG_NONE_MATCH_DATA["type"])
         yaml_data.append(CLOUD_SETTING["type"])  # type: ignore
 
     def update_client(self, yaml_data: dict[str, Any]) -> None:
@@ -338,9 +331,10 @@ def update_client(self, yaml_data: dict[str, Any]) -> None:
                     if p["location"] == "header" and wire_name_lower == "client-request-id":
                         yaml_data["requestIdHeaderName"] = wire_name_lower
                     if self.version_tolerant and p["location"] == "header":
-                        if _is_etag_match(p) and not property_if_match:
+                        role = _get_etag_role(p)
+                        if role == "ifMatch" and not property_if_match:
                             property_if_match = p
-                        elif _is_etag_none_match(p) and not property_if_none_match:
+                        elif role == "ifNoneMatch" and not property_if_none_match:
                             property_if_none_match = p
                 # pylint: disable=line-too-long
                 # some service(e.g. https://github.com/Azure/azure-rest-api-specs/blob/main/specification/cosmos-db/data-plane/Microsoft.Tables/preview/2019-02-02/table.json)
@@ -393,20 +387,12 @@ def update_parameter(self, yaml_data: dict[str, Any]) -> None:
             wire_name_lower in HEADERS_HIDE_IN_METHOD or yaml_data.get("clientDefaultValue") == "multipart/form-data"
         ):
             yaml_data["hideInMethod"] = True
-        if self.version_tolerant and yaml_data["location"] == "header" and wire_name_lower in HEADERS_CONVERT_IN_METHOD:
-            headers_convert(yaml_data, HEADERS_CONVERT_IN_METHOD[wire_name_lower])
-        elif (
-            self.version_tolerant
-            and yaml_data["location"] == "header"
-            and yaml_data.get("isEtag")
-            and wire_name_lower not in HEADERS_CONVERT_IN_METHOD
-        ):
-            # Custom etag-typed headers (e.g. x-ms-blob-if-match) get the same
-            # etag/match_condition treatment as standard If-Match/If-None-Match.
-            if _is_etag_none_match(yaml_data):
-                headers_convert(yaml_data, HEADERS_CONVERT_IN_METHOD["if-none-match"])
-            else:
-                headers_convert(yaml_data, HEADERS_CONVERT_IN_METHOD["if-match"])
+        if self.version_tolerant and yaml_data["location"] == "header":
+            role = _get_etag_role(yaml_data)
+            if role == "ifMatch":
+                headers_convert(yaml_data, ETAG_MATCH_DATA)
+            elif role == "ifNoneMatch":
+                headers_convert(yaml_data, ETAG_NONE_MATCH_DATA)
         if wire_name_lower in ["$host", "content-type", "accept"] and yaml_data["type"]["type"] == "constant":
             yaml_data["clientDefaultValue"] = yaml_data["type"]["value"]
 

From c23753c8a442820ab9697c45d4832177d2dfb590 Mon Sep 17 00:00:00 2001
From: iscai-msft <isabellavcai@gmail.com>
Date: Mon, 27 Apr 2026 14:12:42 -0400
Subject: [PATCH 3/6] don't special case for swagger generations

---
 .../generator/pygen/preprocess/__init__.py       | 16 ++--------------
 1 file changed, 2 insertions(+), 14 deletions(-)

diff --git a/packages/http-client-python/generator/pygen/preprocess/__init__.py b/packages/http-client-python/generator/pygen/preprocess/__init__.py
index 4c7a4263d4b..2fc89c5defa 100644
--- a/packages/http-client-python/generator/pygen/preprocess/__init__.py
+++ b/packages/http-client-python/generator/pygen/preprocess/__init__.py
@@ -165,20 +165,8 @@ def get_wire_name_lower(parameter: dict[str, Any]) -> str:
 
 
 def _get_etag_role(parameter: dict[str, Any]) -> Optional[str]:
-    """Return 'ifMatch', 'ifNoneMatch', or None for this header parameter.
-
-    The emitter sets etagRole directly for TypeSpec inputs. For autorest/swagger
-    inputs we fall back to the wire name.
-    """
-    role = parameter.get("etagRole")
-    if role:
-        return role
-    wire = get_wire_name_lower(parameter)
-    if wire == "if-match":
-        return "ifMatch"
-    if wire == "if-none-match":
-        return "ifNoneMatch"
-    return None
+    """Return 'ifMatch', 'ifNoneMatch', or None for this header parameter."""
+    return parameter.get("etagRole")
 
 
 def headers_convert(yaml_data: dict[str, Any], replace_data: Any) -> None:

From e3b61cf6589e87098a8beaebcb5e2fb03df1b5c6 Mon Sep 17 00:00:00 2001
From: iscai-msft <isabellavcai@gmail.com>
Date: Mon, 27 Apr 2026 14:43:16 -0400
Subject: [PATCH 4/6] refactor: clean up etag role detection in emitter

Move etagRole determination into the emitter's getEtagRole() function.
Standard If-Match/If-None-Match headers work with any type.
Non-standard headers (e.g. x-ms-blob-if-match) require Azure.Core.eTag type.
Simplify preprocess _get_etag_role to just read the etagRole field.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
---
 packages/http-client-python/emitter/src/http.ts | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/packages/http-client-python/emitter/src/http.ts b/packages/http-client-python/emitter/src/http.ts
index 0a695e68c6e..07104c972ef 100644
--- a/packages/http-client-python/emitter/src/http.ts
+++ b/packages/http-client-python/emitter/src/http.ts
@@ -54,14 +54,17 @@ function isEtagType(type: SdkType): boolean {
 }
 
 function getEtagRole(parameter: SdkHeaderParameter): string | undefined {
-  if (!isEtagType(parameter.type)) return undefined;
   const name = parameter.name.toLowerCase();
   const wire = parameter.serializedName.toLowerCase();
-  // Check client name first, then wire name
+  // Standard If-Match / If-None-Match headers work with any type
+  if (wire === "if-match") return "ifMatch";
+  if (wire === "if-none-match") return "ifNoneMatch";
+  // Non-standard headers require Azure.Core.eTag type
+  if (!isEtagType(parameter.type)) return undefined;
   if (name.includes("nonematch") || name.includes("none_match")) return "ifNoneMatch";
   if (name.includes("match")) return "ifMatch";
-  if (wire.endsWith("if-none-match") || wire === "if-none-match") return "ifNoneMatch";
-  if (wire.endsWith("if-match") || wire === "if-match") return "ifMatch";
+  if (wire.endsWith("-if-none-match")) return "ifNoneMatch";
+  if (wire.endsWith("-if-match")) return "ifMatch";
   return undefined;
 }
 

From a1fc7a609005fa47fe15541e1698826a15559d78 Mon Sep 17 00:00:00 2001
From: iscai-msft <isabellavcai@gmail.com>
Date: Mon, 27 Apr 2026 14:45:12 -0400
Subject: [PATCH 5/6] chore: update changeset description

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
---
 .../changes/python-etagMatchCondition-2026-04-27-13-33-08.md    | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/.chronus/changes/python-etagMatchCondition-2026-04-27-13-33-08.md b/.chronus/changes/python-etagMatchCondition-2026-04-27-13-33-08.md
index be12b4f1143..b5352021d82 100644
--- a/.chronus/changes/python-etagMatchCondition-2026-04-27-13-33-08.md
+++ b/.chronus/changes/python-etagMatchCondition-2026-04-27-13-33-08.md
@@ -4,4 +4,4 @@ packages:
   - "@typespec/http-client-python"
 ---
 
-Convert custom etag-typed headers (e.g. `x-ms-blob-if-match`) to `etag`/`match_condition` parameters, matching the standard `If-Match`/`If-None-Match` behavior while preserving the original wire name for the HTTP header
+Support custom wire names for etags defined with `Azure.Core.eTag` (e.g. `x-ms-blob-if-match`)

From e327a0de575812e60bca6fd31ddefb1f580f81ce Mon Sep 17 00:00:00 2001
From: iscai-msft <isabellavcai@gmail.com>
Date: Tue, 28 Apr 2026 11:15:52 -0400
Subject: [PATCH 6/6] fix duplicate arg issue

---
 .../http-client-python/generator/pygen/preprocess/__init__.py   | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/packages/http-client-python/generator/pygen/preprocess/__init__.py b/packages/http-client-python/generator/pygen/preprocess/__init__.py
index 2fc89c5defa..bc595e1748a 100644
--- a/packages/http-client-python/generator/pygen/preprocess/__init__.py
+++ b/packages/http-client-python/generator/pygen/preprocess/__init__.py
@@ -330,9 +330,11 @@ def update_client(self, yaml_data: dict[str, Any]) -> None:
                 if not property_if_match and property_if_none_match:
                     property_if_match = property_if_none_match.copy()
                     property_if_match["wireName"] = "if-match"
+                    property_if_match["etagRole"] = "ifMatch"
                 if not property_if_none_match and property_if_match:
                     property_if_none_match = property_if_match.copy()
                     property_if_none_match["wireName"] = "if-none-match"
+                    property_if_none_match["etagRole"] = "ifNoneMatch"
 
                 if property_if_match and property_if_none_match:
                     # arrange if-match and if-none-match to the end of parameters