# WETH-quote roundtrip probe (#2265), ppdata 13 Oct
- Cause of weth_quote_unsupported: the WETH token (0x0bd7d308f8e1639fab988df18a8011f41eacad73, proxy, OZ-upgradeable) keeps balances at storage slot 51 and allowances at slot 52; sellprobe only tries slots 0-11. Verified by balanceOf/allowance overrides = BIG. Permit2 pull from W also works.
- Patched /opt/sw/roundtrip/rt4.py (backup rt4.py.bak_ppdata_1013): falls back to slots 51/52. rtd.py NOT restarted (ppfeeds owns it).
- NOT solved: with the slots fixed, the buy swap on weth pools still reverts with empty data inside the UniversalRouter v4 unlock callback, before any PoolManager.swap call (even action [SWAP_EXACT_IN_SINGLE] alone). Same code works on native pools. No debug_traceCall structLogs available on the free RPC, so I could not see the opcode. Suspects: key order/pool_key for weth pools, or UR rejecting params when currency0 is an ERC20.
- Next: compare pool_key output with a real weth buy tx calldata (decode one real UR execute on a weth pool from the chain) and mirror its encoding.