Background GC jobs reference

[codebestia]

Write apps/backend/docs/concepts-gc-jobs.md covering every scheduled cleanup: services/deviceGc.ts, services/envelopeGc.ts, services/fileCleanup.ts, the prekey/key-package pruning, and the push-subscription backoff re-enable pass.

Acceptance criteria:

• Each job documented with schedule, what it removes, its retention window, and the env var that configures it
• Explains the idempotency and retry-safety of each — notably that a file's hardDeletedAt is set only after a successful object-store delete, so a crash between the two is safe to retry
• Documents the reference-counting check that stops a still-referenced file being deleted
• States which jobs run in-process on every gateway node and the implications for a multi-node deployment

[fathiaoyinloye]

@fathiaoyinloye has applied to work on this issue as part of the Stellar Wave Program's 8th wave.

Hi, I'd like to work on this issue. I have relevant experience with the technologies and concepts involved, and I'm confident I can make the necessary implementation to ensure the it meets the acceptance criteria. I'd be happy to contribute to this task.

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

[ezekielnathaniel070-ai]

@ezekielnathaniel070-ai has applied to work on this issue as part of the Stellar Wave Program's 8th wave.

I would sincerely love to work on this issue because I have strong experience in working and dealing with complex workflow logic.

ℹ️ Repo Maintainers: To accept this application, review their application or assign @ezekielnathaniel070-ai to this issue.

[Dannyorji]

@Dannyorji has applied to work on this issue as part of the Stellar Wave Program's 8th wave.

Hi Maintainer
Can i be assigned this?

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

[drips-wave]

Congratulations, @Dannyorji! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on August 31, 2026.

🧑‍💻 @Dannyorji: 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 🌊

[github-actions]

Closed by #598, merged into dev.

[drips-wave]

This issue has been completed by @Dannyorji as part of the Stellar Wave Program's 8th Wave 🥳

😎 @Dannyorji: You earned 200 Points for completing this issue! After the current Wave ends, you'll be eligible for a percentage of the Wave's reward pool based on the percentage of total points you've earned. Learn more here. You can also Leave a review to share your experience working on this issue.

🧑‍💻 Repo maintainers: How'd the contributor do? Leave a review to share your experience working with them.