`content_type`-specific validation on the file-message send path

[codebestia]

lib/validateMessagePayload.ts is the shared validator used by the REST send path and the main send_message socket handler. send_file_message has its own inline, weaker checks and never calls the shared validator, so file messages skip the envelope-presence rule entirely.

Acceptance criteria:

• send_file_message calls the same validateMessagePayload the other send paths use
• Land this together with the envelope-migration issue — the file-type rule requires envelopes and send_file_message doesn't create any yet in isolation
• lib/validateMessagePayload.ts remains the single source of truth for send-payload validity, referenced by every send path

[richardgittest]

@richardgittest has applied to work on this issue as part of the Stellar Wave Program's 7th wave.

Hi Maintainer, I would love to work on this

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

[TheEmmaIhezie]

@TheEmmaIhezie has applied to work on this issue as part of the Stellar Wave Program's 7th wave.

I would like to work on this issue because consistent validation is a key principle of secure software development. Having different validation logic for different message send paths can lead to inconsistent behavior, security gaps, and maintenance challenges. Consolidating validation around a single shared validator ensures that all message types are subject to the same security and integrity checks while reducing duplication and the risk of future regressions.

My relevant experience comes from my cybersecurity background, where I have developed knowledge of secure software development, input validation, backend security, and defensive programming. I also have experience working with JavaScript/TypeScript, backend development, Git, and GitHub, and I am actively contributing to open-source projects that emphasize code quality, security, and maintainability.

I am interested in contributing to this issue because it combines backend engineering, security, and code maintainability. I will ensure that send_file_message uses the shared validateMessagePayload function, preserve validateMessagePayload.ts as the single source of truth for message validation, coordinate the implementation with the envelope migration requirements, and include appropriate tests to verify consistent validation behavior across every message send path.

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

[Ajibola6921]

@Ajibola6921 has applied to work on this issue as part of the Stellar Wave Program's 7th wave.

Hello Maintainer, I'd be glad to take responsibility for this issue and submit a high-quality pull request for your review.

ℹ️ Repo Maintainers: To accept this application, review their application or assign @Ajibola6921 to this issue.

[johdanike]

@johdanike has applied to work on this issue as part of the Stellar Wave Program's 7th wave.

I'd love to take this on! I will integrate the shared validateMessagePayload into the send_file_message socket handler to ensure the envelope-presence rule is strictly enforced across all send paths, maintaining a single source of truth. I'll also ensure this is landed together with the envelope-migration issue to satisfy the file-type envelope requirement. Let me know if I can get assigned!

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

[drips-wave]

Congratulations, @johdanike! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on July 30, 2026.

🧑‍💻 @johdanike: 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 🌊