fix(sandboxes): retry upload response read errors

[xeophon]

File uploads now recover from transient response-read failures instead of immediately aborting sandbox setup. Both synchronous and asynchronous file and bytes uploads retry httpx.ReadError using the existing four-attempt upload budget and exponential backoff.

Retries resend the same bytes to the same destination and share the budget with existing transient HTTP retries. The generic POST retry policy remains unchanged. If a bytes upload ultimately fails, its error includes the exception type and preserves the original cause.

---

Note

Low Risk
Idempotent upload retries only; behavior change is limited to recovering transient network/read failures without altering auth, 409, or generic POST retry policies.

Overview
Sandbox uploads now treat transient httpx.ReadError (failures while reading the gateway response) like existing 408/5xx retries, instead of failing immediately.

Sync and async upload_file and upload_bytes route ReadError through _should_retry_upload_error, which shares the same MAX_409_RETRIES attempt counter and exponential backoff as other transient upload errors. upload_bytes also surfaces failures with the exception type and chains the original cause when retries are exhausted.

New parametrized tests cover sync/async clients, file vs bytes uploads, and exhaustion after the retry budget.

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[chatgpt-codex-connector]

Codex Review Summary

This comment shows the latest Codex review activity on this pull request.

Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-09-06T15:11:21.611231Z	bf14b90	PR opened

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