A store-level retry for a provider 5xx stacked on top of the retries the
embedding wrapper and the provider SDK already perform, so a batch the SDK
answered after 12 attempts became 36. Retry ownership stays with those
layers; the store answers a provider-wide 5xx once and gives up.
Transport failures keep their retry because they describe a connection that
no lower layer has reported, and the opt-in quota policy is untouched.
Tests updated to pin the new boundary: a 503 is answered once for the
OpenAI-shaped, Gemini-shaped and DashScope-shaped errors, while a 429 keeps
its retry from the rate-limit branch.
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