Bug: get_parameters_by_name and get() use different cache keys, so they never share cache entries #8593

Expected Behaviour

A parameter fetched by get("/a") is served from cache by a following get_parameters_by_name({"/a": {}}), and the other way around, as long as it is fresh.

Current Behaviour

get_parameters_by_name builds its cache key as (name, transform) (ssm.py:566 and :664), while BaseProvider._build_cache_key builds (name, transform, is_nested). The two never match, so the same parameter is fetched twice and stored twice. Inside get_parameters_by_name itself, a parameter that goes through the decrypt path (get()) and later through the batch path is also fetched again.

Code snippet

from botocore.config import Config
from botocore.stub import Stubber
from aws_lambda_powertools.utilities.parameters import SSMProvider

provider = SSMProvider(boto_config=Config(region_name="us-east-1"))
stub = Stubber(provider.client)
resp1 = {"Parameter": {"Name": "/a", "Value": "v", "Type": "String", "Version": 1}}
resp2 = {"Parameters": [{"Name": "/a", "Value": "v", "Type": "String", "Version": 1}]}
stub.add_response("get_parameter", resp1, {"Name": "/a", "WithDecryption": False})
stub.add_response("get_parameters", resp2, {"Names": ["/a"]})
stub.activate()

provider.get("/a")
provider.get_parameters_by_name({"/a": {}})   # second API call for a value that is fresh in cache
print(list(provider.store))  # [('/a', None, False), ('/a', None)]

Possible Solution

Use self._build_cache_key(name=name, transform=transform) in both places in ssm.py instead of building the tuple by hand.

Steps to Reproduce

Run the snippet above (it uses botocore.stub.Stubber, no AWS access needed).

Powertools for AWS Lambda (Python) version

latest

AWS Lambda function runtime

3.13

Packaging format used

PyPi

Debugging logs