Grant submissions are unreachable: add a grant application path or reject grants in submit explicitly

[0xdevcollins]

Source: docs/threat-model.md v1.0, DoS.13 (Priority 3, Open).

Problem

submit requires a prior application for Pillar::Bounty | Pillar::Grant (event_ops.rs:573), but apply_to_bounty accepts only Pillar::Bounty (bounty.rs, require_active_bounty). A grant submit therefore always fails with ApplicantNotApplied. Fail-closed, so no security impact, but a dead path that will confuse integrators and auditors.

Options

• Generalise the application entry point to grants (apply_to_event), or
• Make submit reject grant events with a dedicated error (grants proceed through owner-driven selection and milestone claims without on-chain submissions).

Done when

The chosen behaviour is tested for all four event types and Appendix A of the threat model is updated.

[abojeEdwin]

Hi maintainer, I've gone through the issue and I have a clear understanding of the fix for this issue. I'd love to be assigned to this issue. Thank you

[Okorie2000-code]

The issue description is crystal clear, and I’d be glad to work on it. I’ll ensure the implementation is clean, tested, and submit a clean PR. Kindly assign it to me. 🙏

[guptakumarranjeet150]

Hi maintainers,

I am interested in working on this issue.
Plan:

1. Implement Grant submissions are unreachable: add a grant application path or reject grants in submit explicitly with thorough authorization verification and clean data structures.
2. Ensure contract compiles cleanly and passes all cargo tests without warnings.

I am ready to start immediately—please feel free to assign this to me!