Strict content-type negotiation: only `application/json` accepted

[usmanimamu17-create]

Problem

Endpoints accept Content-Type: text/plain; Pydantic may silently parse.

Why

Loose content types enable param smuggling via alternate encodings.

Outcome

Middleware returns 415 for non-JSON/multipart. Multipart exempted.

Acceptance

• POST with text/plain → 415
• POST JSON works case-insensitively
• Multipart unchanged

Files

• app/middleware/content_type.py (NEW)
• app/main.py

[oluseguntaiwojoel-lab]

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

I would love to work on this issue because I have what it takes to get the job done

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[abbaskachia]

@abbaskachia 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 enforcing strict Content-Type validation is an important security improvement that helps prevent malformed requests and content-type smuggling while ensuring the API behaves consistently.

I have experience working with Python, FastAPI, backend development, and open-source projects. For this task, I will implement middleware to enforce the accepted request content types, preserve existing multipart upload behavior, integrate the middleware into the application, and add or update tests to verify valid JSON requests succeed while unsupported content types correctly return HTTP 415 without affecting existing functionality.

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[penielgold-hub]

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

Hello maintainer, I would like to work on this issue

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[Salauayo]

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

Hi maintainer, kindly assign this to me. I’m a full-stack developer and can submit the PR within 24 hours.

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[Tenny150]

@Tenny150 has applied to work on this issue as part of the Stellar Wave Program's 7th wave.

I will like to apply for this

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[drips-wave]

Congratulations, @Tenny150! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on July 30, 2026.

🧑‍💻 @Tenny150: 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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