Python runtime can double-decode compressed responses

[hardbyte]

Summary

reflectapi-runtime can double-decode compressed responses in the Python runtime request path.

When the transport layer returns a response body that has already been decompressed, but the response headers still include Content-Encoding: gzip (or another compression encoding), _make_request rebuilds an httpx.Response with those headers and that already-decoded body. httpx.Response(..., content=...) then attempts to decode the body again and raises a decoding error before the generated client can deserialize the API response.

Observed error

httpx.DecodingError: Error -3 while decompressing data: incorrect header check
...
reflectapi_runtime.exceptions.NetworkError: Network error: Error -3 while decompressing data: incorrect header check

Why this appears to happen

In reflectapi_runtime.client, _make_request builds a new httpx.Response from the structural response:

parsed_response = httpx.Response(
    status_code=client_response.status,
    headers=client_response.headers,
    content=client_response.body,
)

If client_response.body is already decoded but client_response.headers still contains Content-Encoding: gzip, the reconstructed httpx.Response treats the decoded JSON bytes as gzip bytes and fails.

Expected behavior

The runtime should successfully validate/deserialise the response regardless of whether the underlying transport has already decompressed it.

Possible fixes:

• strip Content-Encoding / related compression headers when rebuilding an httpx.Response from an already-decoded structural body
• preserve the raw compressed body when preserving compression headers
• avoid constructing a second decoding httpx.Response for validation

Workaround

Passing Accept-Encoding: identity in the generated client headers avoids the issue by preventing compressed responses:

client = AsyncClient(base_url, headers={"Accept-Encoding": "identity"})

That is functional, but it is surprising and loses compression for all requests.

Environment

• reflectapi-runtime: observed with 0.17.6
• Python generated client using AsyncClient
• Server response: JSON response with compression enabled