Call semantics, pools, and failures — Codex & MCP

When to use

Use explicit methods when execution differs from the service default or requires a pool, priority, parallelism, or error path.

Behavior

• function_call invokes the target directly under normal in-process semantics.
• task_pool_call submits work to a named pool; priority_task_pool_call also requires an explicit priority.
• parallel_call dispatches an existing edge independently. Use Split to create fan-out branches; a call-semantic method neither creates the edge nor changes source-count rules.
• An Error stream and error edge represent failure flow; they are not equivalent to a normal data edge.

Example

process_inventory >> reserve_inventory
process_inventory.priority_task_pool_call(
    reserve_inventory,
    pool=inventory_workers,
    priority=10,
)
process_inventory | inventory_error

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