Retries

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SDK default (maxRetries / max_retries = 3)

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Retry on

• Network timeout
• DNS failure
• Connection reset
• HTTP 408, 429
• HTTP 500, 502, 503 (and other 5xx)

Backoff: exponential (1s, 2s, 4s, … capped).

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Never retry

• 400, 401, 403, 404, 409, 422 (and other non-retryable 4xx except 408/429)

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Never retry (provider)

The presigned PUT to S3/R2/B2 is not retried by the SDK. Provider behavior and stream/body constraints are outside BlobRouter’s control.

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Custom HTTP clients

Mirror the same policy. Honor Retry-After on 429. Include X-Request-ID when contacting support after exhausted retries.