[Sandbox] Add docs for Sandbox S3 credential proxy

[scuffi]

Summary

This PR adds documentation for the S3 mount credential proxy implemented in cloudflare/sandbox-sdk#727

Documentation checklist

• The change adheres to the documentation style guide.

[github-actions]

This pull request requires reviews from CODEOWNERS as it changes files that match the following patterns:

Pattern	Owners
/src/content/docs/sandbox/	@whoiskatrin, @ghostwriternr, @scuffi, @aron-cf, @thomasgauvin, @cloudflare/product-owners, @cloudflare/ai-agents

[ask-bonk]

Clean documentation addition. One minor style guide fix suggested inline.

Summary: This PR adds documentation for the credentialProxy option in the Sandbox SDK, which routes S3 requests through a Durable Object proxy to keep real credentials out of the container. Changes span the Storage API reference (storage.mdx) and the Mount Buckets guide (mount-buckets.mdx).

Issue to address:

• LOW src/content/docs/sandbox/api/storage.mdx:179 — Uses a semicolon. The style guide advises avoiding semicolons — break into shorter sentences instead. Inline suggestion posted.

Note: Consider updating the PR title to [Sandbox] Add docs for S3 credential proxy to match commit conventions.

[ask-bonk]

Reviewed PR #31202. I posted an inline suggestion and added labels.

Findings:

• LOW src/content/docs/sandbox/api/storage.mdx:179 — New text uses a semicolon, which the style guide advises avoiding. Posted an inline suggestion to split into two sentences.
• Note — The PR title does not follow the commit convention format ([Product] description). Consider updating to [Sandbox] Add docs for S3 credential proxy.

Labels applied: documentation, content:new, size/xs

The PR is otherwise clean — accurate technical content, correct use of TypeScriptExample, proper heading structure, and valid frontmatter.

github run

[github-actions]

Preview URL: https://9955af71.preview.developers.cloudflare.com
Preview Branch URL: https://scuffi-s3-credential-proxy.preview.developers.cloudflare.com

Files with changes (up to 15)

Original Link	Updated Link
https://developers.cloudflare.com/sandbox/guides/mount-buckets/	https://scuffi-s3-credential-proxy.preview.developers.cloudflare.com/sandbox/guides/mount-buckets/
https://developers.cloudflare.com/sandbox/api/storage/	https://scuffi-s3-credential-proxy.preview.developers.cloudflare.com/sandbox/api/storage/

[cloudflare-docs-bot]

Review

✅ No style-guide issues found in commit 9955af7.

Commands

Only codeowners can run commands. Post a comment with the command to trigger it.

Command	Description
/review	Runs a review now. Incremental if a prior review exists, full if not.
/full-review	Re-reviews the entire PR diff from scratch, ignoring incremental history. Useful after a rebase, when you want a fresh review, or if the bot gets out of sync and reports issues that no longer exist.

[devin-ai-integration]

✅ Devin Review: No Issues Found

Devin Review analyzed this PR and found no potential bugs to report.

View in Devin Review to see 1 additional finding.