Fee-Optimized Execution (Maker-First Orders)
Updated May 22, 2026 · 1 min read
Cut trading fees with maker-first orders, tune the fallback to market for fill certainty, and handle the 2026 order-options schema change.
FEE_OPTIMIZED_LIMIT places a maker ALO order - cheaper than MARKET (taker). With [Runtime 1.1.0](https://github.com/Senpi-ai/senpi-trading-runtime) (May 2026), maker-first is the default on entries and exits, so most agents do not need to specify orderType per call.
Controlling fallback behaviour
Option A
ensureExecutionAsTaker: true - Fill certainty
- Falls back to market after
executionTimeoutSeconds(default 45s) - Use when execution certainty matters
- ✗ Pays taker fee on fallback
Option B
Omit (or false) - Fee minimization
- Order stays maker indefinitely
- Cheapest possible fees
- ✗ May rest until filled or cancelled
Schema migration (March 2026)
The ensureExecutionAsTaker flag is no longer a top-level field on Senpi MCP calls. It moved into the feeOptimizedLimitOptions object. New shape:
{
orderType: 'FEE_OPTIMIZED_LIMIT',
feeOptimizedLimitOptions: { ensureExecutionAsTaker: true, executionTimeoutSeconds: 30 }
}If you hit a DEPRECATED_FIELD error mentioning ensureExecutionAsTaker, update your agent's MCP client or skill to the new schema.
Also note: edit_position and close_position no longer accept orderType: LIMIT. They return EDIT_LIMIT_NOT_SUPPORTED or CLOSE_LIMIT_NOT_SUPPORTED if you pass it. See article 13 for full position-management semantics.
For cancelling fee-optimized orders that may rest indefinitely, see article 13 on cancel_order.
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