signature_type=2 (POLY_GNOSIS_SAFE) — POST /order returns 401 with valid credentials

[sirlancelot22]

Setup

• Package: py-clob-client-v2 v1.0.1rc1 (from PyPI)
• Python 3.14 on Windows 10
• ClobClient configured per the V2 migration docs:
  • host="https://clob.polymarket.com"
  • chain_id=137
  • signature_type=2 (POLY_GNOSIS_SAFE)
  • funder=<my Polymarket proxy address>
  • key=<my EOA private key>

What works

• L1 derivation: client.create_or_derive_api_key() returns valid credentials
• L2 reads: GET /auth/api-keys returns 200 with the key listed
• I verified the SDK's build_hmac_signature matches a manual implementation byte-for-byte
• Public endpoints: GET /time, GET /markets, GET /book all work fine

What fails

client.create_and_post_order(...) consistently returns:
PolyApiException[status_code=401, error_message={'error': 'Unauthorized/Invalid api key'}]

Diagnostic

I tested a manually-signed POST /order with the same payload (built via create_order()) varying just the POLY_ADDRESS header:

POLY_ADDRESS value	Status	Response body
Signer EOA	401	{"error":"Unauthorized/Invalid api key"}
Funder (proxy)	400	{"error":"the order signer address has to be the address of the API KEY"}

Reading these together: with POLY_ADDRESS=signer, L2 auth fails; with POLY_ADDRESS=funder, auth passes but the order validator rejects because the SDK correctly sets order.signer = EOA (since the GnosisSafeProxy contract has no signing key) while the validator appears to require order.signer == api_key_owner_address.

For a Gnosis Safe Proxy, those addresses are different by design.

Reproducibility

Reproduced on a brand-new wallet (different EOA, different proxy, freshly derived credentials). Same failure pattern. Not account-specific state.

Question

Is signature_type=2 currently functional for POST /order on V2, or is this a known gap awaiting the deposit wallet (signature_type=3 / POLY_1271) rollout?

If a workaround exists for existing Gnosis Safe Proxy users, would appreciate guidance. Happy to provide a minimal reproduction script.