feat: add DiscountEligibilityCheckRequested filter

[pwnage101]

Adds a new DiscountEligibilityCheckRequested filter to the learning subdomain, enabling plugins to mark users as ineligible for LMS-controlled course discounts without coupling the core platform to enterprise-specific logic.

ENT-11564

Co-Authored-By: Claude Sonnet 4.6 noreply@anthropic.com

---

Blocks:

• feat: add DiscountEligibilityStep pipeline step edx-enterprise#2545
• feat: replace enterprise_support import with DiscountEligibilityCheckRequested filter openedx-platform#38099

[pwnage101]

make type more explicit.

[pwnage101]

Don't forget to also bump the version.

[pwnage101]

Should reference openedx/openedx-platform, not the legacy openedx/edx-platform path.

[pwnage101]

Use strict dict access here: data["user"], data["course_key"], data["is_eligible"]. Per the convention established on #333, data.get(...) lets a buggy pipeline step silently drop a key — None would then propagate into the caller and falsy-evaluate as ineligible. We want a KeyError raised inside the pipeline instead.

[pwnage101]

Tighten the return annotation from bare tuple to tuple[Any, Any, bool] (or, better, concrete User / CourseKey types alongside fixing the input annotations below). Per #333, leaving this as a wide tuple allows a buggy step to return None for required values without the type checker flagging it.

[marlonkeating]

Done for CourseKey, omitting for User as the type is not referenced anywhere in the file and we would need to do something like User = get_user_model(), which I imagine we shouldn't do just to get a Type annotation.

[pwnage101]

You actually can use AbstractBaseUser from django. See my draft PR for a different ticket: https://github.com/openedx/openedx-filters/pull/336/changes#diff-0c79edd111d62405dc0829ac0b0b971c73b410de87c0133a7190b3de08b40ed9

from django.contrib.auth.base_user import AbstractBaseUser
[...]
    def run_filter(cls, user: AbstractBaseUser, course_key: CourseKey) -> tuple[AbstractBaseUser, CourseKey]:

[pwnage101]

The docstring below already names User and CourseKey or course object — lift those into the annotations (user: User, course_key: CourseKey) so input and output align and Any doesn't drift in.

[pwnage101]

Per the minimal-test convention from #334, the canonical test for a new filter in this repo verifies inputs pass through unchanged when no pipeline is configured — mirror test_schedule_requested directly above. The override-to-False case exercises pipeline-step behavior and belongs alongside the pipeline-step implementation in edx-enterprise, not here.

[pwnage101]

❌ Simplify the output type to remove ambiguity---None values should not be allowed.

Suggested change

	def run_filter(
	cls,
	user: Any,
	course_key: CourseKey,
	is_eligible: bool,
	) -> tuple[Any, CourseKey | None, bool | None]:
	def run_filter(
	cls,
	user: AbstractBaseUser,
	course_key: CourseKey,
	is_eligible: bool,
	) -> tuple[AbstractBaseUser, CourseKey, bool]:

[pwnage101]

See also my comment on an older thread about AbstractBaseUser: #335 (comment)

[pwnage101]

Nit: since it only takes one pipeline step to deem the entire discount ineligible, every pipeline step implementation must take care to skip itself when is_eligible=False to prevent clobbering a prior step which set it to False. This pushes complexity into 3rd party code when there's really a much simpler solution:

We could make pipeline steps simply raise an OpenEdxFilterException exception. There are many examples in this same file, including StudentRegistrationRequested.PreventRegistration:
https://github.com/edx/openedx-filters/blob/main/openedx_filters/learning/filters.py#L161

This has the side-benefit of providing a clean way to pass error messages from the caller without polluting the run_filter() signature. See my in-progress work for a different ticket: https://github.com/openedx/openedx-filters/pull/336/changes

Notably:

class CoursewareAccessChecksRequested(OpenEdxPublicFilter):
   [...]

    class PreventCoursewareAccess(OpenEdxFilterException):
        [...]

        def __init__(
            self,
            error_code: str,
            developer_message: str,
            user_message: str,
        ) -> None:
            super().__init__()
            self.error_code = error_code
            self.developer_message = developer_message
            self.user_message = user_message