Polymarket provider: /trades paging uses market+offset, both rejected by Data API v2 (v1 retired 2026-10-24) #132

Polymarket retires Data API v1 on 2026-10-24 (migration guide). This repo still calls v1 routes at HEAD:

• src/ml4t/data/providers/polymarket.py:1549: params {"market": condition_id, "limit": …, "offset": offset}
• src/ml4t/data/providers/polymarket.py:1555: GET {DATA_API_URL}/trades

What changes in v2 (verified live on 2026-10-23):

• the response is {data: [...], pagination: {next_cursor, has_more}} instead of a bare array
• fields are snake_case (asset→token_id, conditionId→condition_id, size→current_size, curPrice→current_price, cashPnl→unrealized_pnl, usdcSize→usdc_size)
• pagination is cursor-only: offset and market now return HTTP 400 (use cursor and condition)

On /v2/trades, market→condition and offset is rejected with 400. Pagination follows pagination.next_cursor, and the docs say v2 cursors stay consistent while new rows arrive. That could replace the offset-cap / end-shifting logic and the repeated-page guard. Record keys become snake_case (transaction_hash, token_id, proxy_wallet), which matters for your dedup key.

Happy to open a PR for this if that's easier for you.

Disclosure: I do Polymarket API migrations as a small freelance service (paid full-repo migration for private forks, if anyone needs one: [email protected]). This note and the fix above are free; feel free to close if you've already handled it.