Use client.ensure_can_trade() alongside position sizing: sizing decides how much, this pre-flight decides whether to trade at all given current wallet balance.
client.ensure_can_trade()
A one-call pre-flight that catches underfunded wallets before you try to place an order. Every rejected trade round-trips to the backend, logs a failure, and gets retried on the next cron tick — replacing the loop with a single status fetch per run is a pure win for skill reliability and observability.
Available in simmer-sdk >= 0.11.1. Collateral-agnostic — reads pUSD on V2 (post-2026-04-28 cutover), USDC.e on V1, so it keeps working across the migration without any code change on your side.
Quick start
from simmer_sdk import SimmerClient
client = SimmerClient()
preflight = client.ensure_can_trade(min_usd=1.0)
if not preflight["ok"]:
# Skip cleanly — harness + automaton reporting distinguish this from "skill broken"
print(f"Skip: {preflight['reason']} (balance ${preflight['balance']:.2f} {preflight['collateral']})")
return
# Cap your per-run size to leave room for fees + slippage
order_size = min(MY_MAX_BET, preflight["max_safe_size"])
Arguments
| Arg | Default | Meaning |
|---|
min_usd | 1.0 | Minimum viable trade size in active collateral. Below this, ok=False. |
venue | client’s venue | Only "polymarket" runs the check. Other venues short-circuit to ok=True. |
safety_buffer | 0.02 | Fraction of balance kept as fee/slippage buffer. max_safe_size = balance × (1 − safety_buffer). |
Returns
A dict with the following keys:
| Field | Meaning |
|---|
ok | True if balance ≥ min_usd (or non-polymarket venue). |
balance | Active collateral balance in USD-equivalent units. |
collateral | "pUSD" (V2), "USDC.e" (V1), or "" (non-polymarket). |
exchange_version | "v1" or "v2" — matches server-side flag. |
reason | "ok", "insufficient_balance", "no_wallet", "balance_unavailable", or "skipped_non_polymarket". |
max_safe_size | balance × (1 − safety_buffer), or 0.0 when ok=False. |
When to call it
Call ensure_can_trade() once per skill run, before any market discovery or signal generation. Running it at the top of your loop costs one REST call and eliminates every downstream rejected order when the wallet is under-funded.
- Underfunded → emit a skip report (
skip_reason="insufficient_balance") and return. The automaton reporter will surface this cleanly, distinct from “skill broken.”
- Sized correctly → clamp your per-run
MAX_BET_USD (or equivalent) to max_safe_size so you leave headroom for fees + price slippage.
Why not just trust client.get_portfolio()?
You can — but ensure_can_trade() bundles three things you’d otherwise re-implement in every skill:
- Collateral-agnostic balance selection: reads the correct token for the active
exchange_version (pUSD on V2, USDC.e on V1).
- Failure-mode distinction: returns a stable
reason string across RPC outages, missing wallets, and genuine zero-balance cases.
- Safety buffer math: the
max_safe_size return is already clamped for fees and slippage — no off-by-one between skills.
