Correct task-product input/output semantics in ifcos-impl-sequence

[PahlawanJoey]

repro_ap10.py

Summary

This PR corrects the task-to-product relationship documented by the ifcos-impl-sequence skill.

The current AP-10 guidance reverses IFC input/output semantics:

• A product constructed or installed by a task is a task output and should be linked using sequence.assign_product.

• A product used, consumed, demolished, maintained, or otherwise operated on by a task is a task input and should be linked using sequence.assign_process.

The affected guidance has been made consistent across the skill, examples, anti-patterns, and method reference.

Problem

AP-10 currently presents sequence.assign_process as the standard way to link a construction task to the product it creates, while marking sequence.assign_product as incorrect.

This contradicts:

• the decision tree elsewhere in the same skill;

• the existing assign_product method reference;

• the official IfcOpenShell API documentation;

• the behaviour of ifcopenshell.util.sequence.

It also incorrectly describes assign_product as meaning that a product “controls” a task. IFC controls use IfcRelAssignsToControl, which is a different relationship.

Correct IFC semantics

Purpose | IfcOpenShell API | IFC relationship | Standard query -- | -- | -- | -- Product built or installed by a task | sequence.assign_product(relating_product=product, related_object=task) | IfcRelAssignsToProduct | get_task_outputs(task) Product used or operated on by a task | sequence.assign_process(relating_process=task, related_object=product) | IfcRelAssignsToProcess / IfcTask.OperatesOn | get_task_inputs(task) Control assigned to a task | Control assignment API | IfcRelAssignsToControl | Separate control relationship

A minimal verification is:

sequence.assign_product(
    model,
    relating_product=constructed_wall,
    related_object=construction_task,
)
assert constructed_wall in ifcopenshell.util.sequence.get_task_outputs(

construction_task

)
sequence.assign_process(

model,

relating_process=demolition_task,

related_object=existing_wall,

)
assert existing_wall in ifcopenshell.util.sequence.get_task_inputs(

demolition_task

)

Following the previous AP-10 recommendation causes a newly constructed wall to appear as an input in OperatesOn, while get_task_outputs(task) remains empty.

Additional API correction

The general v0.8+ warning about passing products as a list incorrectly used assign_process as an example.

In IfcOpenShell 0.8.5:

• sequence.assign_process accepts one related_object;

• sequence.assign_product accepts one related_object.

The updated text names APIs that actually use list arguments and avoids applying that rule to APIs with singular parameters.

Files updated

• skills/ifcopenshell/impl/ifcos-impl-sequence/SKILL.md

• skills/ifcopenshell/impl/ifcos-impl-sequence/references/anti-patterns.md

• skills/ifcopenshell/impl/ifcos-impl-sequence/references/examples.md

• skills/ifcopenshell/impl/ifcos-impl-sequence/references/methods.md

References

• IfcOpenShell assign_product

• IfcOpenShell assign_process

• IfcOpenShell sequence utilities

This is a documentation-only correction; no runtime code is changed.