fix: await upload session registration

[danny-avila]

I fixed the upload authorization race that could register files under unusable upload:null... keys by making Redis session registration a strict prerequisite for file-server forwarding.

• Awaited the session-key SET before every /upload PUT.
• Shared one request-scoped registration promise across /upload/batch so every file waits for the same completed write.
• Drained upload streams and returned HTTP 500 when batch session registration fails.
• Added deterministic regression coverage for ordering, shared batch registration, and registration failure.

Fixes #40

Change Type

• Bug fix (non-breaking change which fixes an issue)

Testing

• Ran cd service && bun run build.
• Ran cd service && bun run test: 523 tests passed.
• Ran cd service && bun test src/service/upload-session.test.ts --rerun-each 20: 60 repeated tests passed.

Test Configuration:

• Bun 1.3.13
• macOS

Checklist

• My code adheres to this project's style guidelines
• I have performed a self-review of my own code
• I have commented in any complex areas of my code
• My changes do not introduce new warnings
• I have written tests demonstrating that my changes are effective or that my feature works
• Local unit tests pass with my changes

[danny-avila]

@codex review

[chatgpt-codex-connector]

💡 Codex Review

Here are some automated review suggestions for this pull request.

Reviewed commit: a8a32604f7

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[danny-avila]

@codex review

[chatgpt-codex-connector]

Codex Review: Didn't find any major issues. Delightful!

Reviewed commit: ed3e94e41f

ℹ️ About Codex in GitHub

Your team has set up Codex to review pull requests in this repo. Reviews are triggered when you

• Open a pull request for review
• Mark a draft as ready
• Comment "@codex review".

If Codex has suggestions, it will comment; otherwise it will react with 👍.

Codex can also answer questions or update the PR. Try commenting "@codex address that feedback".