[Backend] Implement Task Payload Size and Argument Validation Hardening

[ayomideadeniran]

Contributor Focus: [Input Hardening] Protect backend and contract paths from malformed or extreme task payloads
ETA: 2 days

Context

Task payloads and execution arguments may vary widely and can become a source of edge-case failures or abuse.

Problem

Weak validation around payload shape and size can cause performance issues, unexpected failures, or unsafe assumptions.

Task Breakdown

1. Review where task payloads and arguments enter the system.
2. Define size and structural validation rules.
3. Ensure failures are reported consistently and early.
4. Add tests for extreme and malformed inputs.
5. Document the constraints for future API or frontend consumers.

Acceptance Criteria

• Malformed or oversized task payloads are rejected predictably.
• Validation happens early enough to avoid wasted work.
• Constraints are documented clearly.
• Tests cover high-risk edge cases.

[MickeeJay]

@MickeeJay has applied to work on this issue as part of the Stellar Wave Program's 4th wave.

Hello Maintainer,
I’ve carefully read the issue and understand what’s needed. I’ll implement this in a way that maintains consistency with the current architecture.

Ready to proceed once assigned.

ℹ️ Repo Maintainers: To accept this application, review their application or assign @MickeeJay to this issue.

[Icebear-16]

@Icebear-16 has applied to work on this issue as part of the Stellar Wave Program's 4th wave.

I'd really love to work on this

ℹ️ Repo Maintainers: To accept this application, review their application or assign @Icebear-16 to this issue.

[drips-wave]

Congratulations, @Icebear-16! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on April 29, 2026.

🧑‍💻 @Icebear-16: Please resolve the issue such that the repo's maintainers have enough time to review your contribution before the due date. You'll earn Points for completing the issue on-time, which will make you eligible for a share of the Stellar Wave Program's reward pool.

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