Module control 

Control operators — side-effect, gating, error recovery, convergence.

Operators

• tap / tap_observer — side-effect passthrough.
• on_first_data — one-shot side-effect on first DATA.
• rescue — error recovery via user callback.
• valve — boolean-gated passthrough with optional cancellation.
• settle — wave-count convergence detector.
• repeat — sequential resubscribe loop.

Functions

on_first_data

One-shot side-effect tap. Calls invoke_tap_fn(fn_id, handle) on the first DATA only, then becomes a pure passthrough. All messages are forwarded unchanged.

repeat

Sequential resubscribe loop. Forwards all DATA from source. On source COMPLETE, if remaining > 0, resubscribes to source and decrements remaining. On ERROR, terminates immediately (no retry).

rescue

Error recovery operator. On ERROR, calls binding.invoke_rescue_fn(fn_id, error_handle):

settle

Wave-count convergence detector.

tap

Passthrough operator that forwards all DATA unchanged. On each DATA, calls binding.invoke_tap_fn(fn_id, handle) as a side-effect. Forwards COMPLETE and ERROR unchanged.

tap_observer

Like tap but with lifecycle observer callbacks. Each callback is optional (None = skip that lifecycle event).

valve

Boolean-gated passthrough. Subscribes to both source and control.