Idempotent Pollers, Retries, and Quarantine Paths

The agent crashed after uploading 40 of 42 files. On restart it uploaded everything again, overwrote nothing useful, emitted two completion markers, and the pipeline ran twice—once on a partial set that somehow got marked ready during the race.

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IAM and KMS Across the Hybrid Lab–Cloud Boundary

Transfer logs said AccessDenied. The bucket policy “allowed S3.” Someone added s3:* on the role and it still failed—because the objects used SSE-KMS and the key policy never trusted the transfer identity.

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Moving Instrument Data to S3 Reliably

The object existed in S3. Size looked right. Downstream parsing failed because the transfer cut off mid-write and a later retry never ran—or ran into a different key. Metrics said “uploaded.” Science said “garbage.”

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