BE-32: Client Contract Compatibility Validation (Schema + Version Checks)

[Cedarich]

Complexity: 150 points
Branch: feat/be-contract-compat
Summary
Prevent clients from interacting with incompatible contract deployments by enforcing schema/version checks in responses and write endpoints.
Tasks

• Define contract schema/version requirements per endpoint/flow.
• Return contract compatibility metadata in key responses (link, quote, pay initiation).
• Reject write requests when contract version is unsupported with clear error codes.
• Add tests covering version mismatches and upgrade transitions.
  Acceptance Criteria
• Unsupported clients receive deterministic, actionable errors.
• Compatibility metadata is consistent across endpoints.
• Upgrade rollouts do not break clients silently.

---

[essiend03-glitch]

@essiend03-glitch has applied to work on this issue as part of the Stellar Wave Program's 5th wave.

please i will like to work on this issue

ℹ️ Repo Maintainers: To accept this application, review their application or assign @essiend03-glitch to this issue.

[drips-wave]

Congratulations, @essiend03-glitch! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on June 2, 2026.

🧑‍💻 @essiend03-glitch: 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.

Warning

When opening a PR, please link it to this issue to ensure it gets tracked accurately. Points are awarded when this issue is marked as completed by the maintainer.

🤠 Repo maintainers: Please keep an eye on the contributor's progress and review their work before the due date. You can manage this issue, including adjusting its complexity and points, here.

🌊 Happy Wave 🌊

[neyij]

@neyij has applied to work on this issue as part of the Stellar Wave Program's 5th wave.

hi, i would like to work on this.

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

[drips-wave]

Congratulations, @neyij! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on June 2, 2026.

🧑‍💻 @neyij: 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.

Warning

When opening a PR, please link it to this issue to ensure it gets tracked accurately. Points are awarded when this issue is marked as completed by the maintainer.

🤠 Repo maintainers: Please keep an eye on the contributor's progress and review their work before the due date. You can manage this issue, including adjusting its complexity and points, here.

🌊 Happy Wave 🌊