feat: add CourseModeCheckoutStarted filter

[pwnage101]

ENT-11573

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Related:

• feat: add CourseModeCheckoutStarted filter #338
• feat: add CalculateEnterpriseDiscountedPrice pipeline step for course mode checkout edx-enterprise#2556
• feat: replace enterprise_customer_for_request with CourseModeCheckoutStarted filter openedx-platform#38109

[pwnage101]

It's unconventional for the return signature to differ from the arguments signature. Better would be:

Suggested change

	return data.get("context")
	return data.get("context"), data.get("request"), data.get("course_mode")

[Copilot]

Pull request overview

This PR introduces a new public filter in the learning subdomain to allow plugins to enrich the checkout context when a user selects a course mode and the checkout flow begins (ENT-11573).

Changes:

• Add CourseModeCheckoutStarted filter (org.openedx.learning.course_mode.checkout.started.v1) with a run_filter(context, request, course_mode) entrypoint.
• Add a unit test validating default pass-through behavior when no pipeline steps are configured.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
openedx_filters/learning/filters.py	Adds the CourseModeCheckoutStarted filter class and metadata docstring.
openedx_filters/learning/tests/test_filters.py	Adds a basic test ensuring the new filter returns the context unchanged by default.

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[pwnage101]

❌ per edx/edx-platform#365 (comment)

[pwnage101]

Here's a version I'd approve quickly (after adding docstrings, unit tests, and conducting integration tests):

from typing import Any, Optional, Protocol

class CourseModePriceRequested(OpenEdxPublicFilter):
    filter_type = "org.openedx.learning.course_mode.price.requested.v1"

    @classmethod
    def run_filter(cls, user: Any, course_mode_data: Any, price: float) -> tuple[Any, Any, float]:
        data = super().run_pipeline(user=user, course_mode_data=course_mode_data, price=price)
        return data["user"], data["course_mode_data"], data["price"]

course_mode_data would be passed a Mode NamedTuple, and price would be the full, non-discounted price.

[pwnage101]

Closing to remind you that you need to re-open this PR from your own openedx-filters branch so that I can approve it.