Idempotent Payloads vs. ETag Conditional Requests for Safe Retries in Portainer API

The goal is to safely retry failed API calls through Portainer without causing duplicate writes when interacting with the Docker daemon via the /api/endpoints/{id}/docker proxy.

Portainer documents that create/update operations are idempotent when the request includes a stable identifier, and that conditional requests using If‑Match/ETag prevent duplicate writes for mutable resources. However, the Docker proxy endpoint does not return a stable ETag in version 2.19.x, making the conditional retry mechanism unreliable, and ad‑hoc commands lack natural idempotency.

• Should clients implement application‑level deduplication using unique request identifiers for proxy calls?
• Is it acceptable to rely solely on idempotent endpoints for resource creation and use external locking or serialization for Docker proxy operations?
• Can a wrapper layer generate and validate client‑side ETags for the proxy endpoint to restore conditional retry safety?