fix: avoid preallocating large buffers for small uploads

[mittalsonal]

Summary

• remove the unconditional 64MB bytes.Buffer preallocation for regular uploads
• size the initial upload buffer from manifest, multipart, or request size hints when available
• keep large uploads capped at the existing 64MB dispatch threshold and let unknown-size uploads grow naturally
• add focused tests for small manifest sizing, large-size capping, request-length fallback, and unknown large uploads

Validation

• git diff --check

Note: Go tooling is not installed in this environment (go/gofmt are unavailable on PATH), so I could not run local Go tests or formatting. GitHub CI should run the Go checks.

Closes #50

[coderabbitai]

Warning

Review limit reached

@mittalsonal, we couldn't start this review because you've reached your PR review rate limit.

More reviews will be available in 52 minutes and 53 seconds. Learn how PR review limits work.

Your organization has used up its prepaid credits, and credit purchases are no longer available. Enable the review add-on in the billing tab to keep reviews running — you're only billed for reviews past your plan's rate limits ($0.25/file).

⌛ How to resolve this issue?

After more reviews become available, a review can be triggered using the @coderabbitai review command as a PR comment. Alternatively, push new commits to this PR.

We recommend that you space out your commits to avoid hitting the rate limit.

🚦 How do rate limits work?

CodeRabbit enforces hourly rate limits for each developer per organization.

Our paid plans include higher PR review limits than trial, open-source, and free plans. In all cases, reviews become available again over time. During sustained high-volume PR review activity, CodeRabbit may temporarily slow when the next review becomes available.

Please see our Fair Usage Limits Policy for further information.

ℹ️ Review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: f46ddd26-1f61-4cdc-9669-3fd2dbc41e9a

📥 Commits

Reviewing files that changed from the base of the PR and between be465d0 and ceb6e56.

📒 Files selected for processing (2)

• beamsync/server.go
• beamsync/server_test.go

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

---

Thanks for using CodeRabbit! It's free for OSS, and your support helps us grow. If you like it, consider giving us a shout-out.

❤️ Share

• X
• Mastodon
• Reddit
• LinkedIn

_{Comment @coderabbitai help to get the list of available commands and usage tips.}