refactor: extract credentail key building logic to auth_config

PiperOrigin-RevId: 768124459

src/google/adk/auth/auth_handler.py

@@ -112,7 +112,7 @@ class AuthHandler:
 
   def parse_and_store_auth_response(self, state: State) -> None:
 
-    credential_key = self.get_credential_key()
+    credential_key = "temp:" + self.auth_config.get_credential_key()
 
     state[credential_key] = self.auth_config.exchanged_auth_credential
     if not isinstance(
@@ -130,7 +130,7 @@ class AuthHandler:
       raise ValueError("auth_scheme is empty.")
 
   def get_auth_response(self, state: State) -> AuthCredential:
-    credential_key = self.get_credential_key()
+    credential_key = "temp:" + self.auth_config.get_credential_key()
     return state.get(credential_key, None)
 
   def generate_auth_request(self) -> AuthConfig:
@@ -192,29 +192,6 @@ class AuthHandler:
         exchanged_auth_credential=exchanged_credential,
     )
 
-  def get_credential_key(self) -> str:
-    """Generates a unique key for the given auth scheme and credential."""
-    auth_scheme = self.auth_config.auth_scheme
-    auth_credential = self.auth_config.raw_auth_credential
-    if auth_scheme.model_extra:
-      auth_scheme = auth_scheme.model_copy(deep=True)
-      auth_scheme.model_extra.clear()
-    scheme_name = (
-        f"{auth_scheme.type_.name}_{hash(auth_scheme.model_dump_json())}"
-        if auth_scheme
-        else ""
-    )
-    if auth_credential.model_extra:
-      auth_credential = auth_credential.model_copy(deep=True)
-      auth_credential.model_extra.clear()
-    credential_name = (
-        f"{auth_credential.auth_type.value}_{hash(auth_credential.model_dump_json())}"
-        if auth_credential
-        else ""
-    )
-
-    return f"temp:adk_{scheme_name}_{credential_name}"
-
   def generate_auth_uri(
       self,
   ) -> AuthCredential:

src/google/adk/auth/auth_tool.py

@@ -12,6 +12,8 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+from __future__ import annotations
+
 from .auth_credential import AuthCredential
 from .auth_credential import BaseModelWithConfig
 from .auth_schemes import AuthScheme
@@ -43,6 +45,34 @@ class AuthConfig(BaseModelWithConfig):
   this field to guide the user through the OAuth2 flow and fill auth response in
   this field"""
 
+  def get_credential_key(self):
+    """Generates a hash key based on auth_scheme and raw_auth_credential. This
+    hash key can be used to store / retrieve exchanged_auth_credential in a
+    credentials store.
+    """
+    auth_scheme = self.auth_scheme
+
+    if auth_scheme.model_extra:
+      auth_scheme = auth_scheme.model_copy(deep=True)
+      auth_scheme.model_extra.clear()
+    scheme_name = (
+        f"{auth_scheme.type_.name}_{hash(auth_scheme.model_dump_json())}"
+        if auth_scheme
+        else ""
+    )
+
+    auth_credential = self.raw_auth_credential
+    if auth_credential.model_extra:
+      auth_credential = auth_credential.model_copy(deep=True)
+      auth_credential.model_extra.clear()
+    credential_name = (
+        f"{auth_credential.auth_type.value}_{hash(auth_credential.model_dump_json())}"
+        if auth_credential
+        else ""
+    )
+
+    return f"adk_{scheme_name}_{credential_name}"
+
 
 class AuthToolArguments(BaseModelWithConfig):
   """the arguments for the special long running function tool that is used to