HuggingFace inference operator: text-gen provider fallback sends Hub model ID instead of providerId to provider-scoped chat routes

[PG1204]

What happened?

The HuggingFace inference operator resolves the providers serving a model (_resolve_providers) and tries them cheapest-first (_post_with_fallback). Each resolved entry carries a providerId, which is the model's name on that provider, which provider-scoped router routes (router.huggingface.co/{provider}/...) require.

For text-generation and image-text-to-text (the default task path), the fallback loop ignores providerId and posts "model": self.MODEL_ID (the Hub ID) to every provider's chat route (PythonCodegenBase.scala ~L203-206 in common/workflow-operator/.../huggingFace/codegen/). Providers whose internal model name differs reject the request with 400/404. _call_provider (other task families) already uses provider_id correctly.

The hf-inference chat URL is also wrong: built as hf-inference/v1/chat/completions, but the endpoint requires the model in the path (hf-inference/models/{model-id}/v1/chat/completions, the form the same file already uses for pipeline tasks). Since hf-inference sorts first in PROVIDER_COST_PRIORITY, the cheapest provider fails on every row.

Effects:

• Text-gen fallback only succeeds when a provider's model name equals the Hub ID; otherwise rows fail with "All inference providers failed" despite live providers.
• Every row wastes at least one doomed request (up to the 120 s timeout) before falling through, inflating latency and rate-limit pressure.

Fix (contained to the text-gen branch of _post_with_fallback): per attempt, send a copy of the payload with "model" set to that provider's provider_id (copy, not mutation, the payload is reused across the loop), and add the models/{model-id} segment to the hf-inference chat URL. Update the generated-code assertions in HuggingFaceInferenceOpDescSpec.scala to pin both behaviors.

How to reproduce?

1. Add the operator with task text-generation and a model whose providerId differs from its Hub ID (see https://huggingface.co/api/models/{id}?expand[]=inferenceProviderMapping).
2. Run with a valid HF token.
3. Rows fail or fall back to pricier providers; the generated Python shows the chat branch posting "model": self.MODEL_ID everywhere and the hf-inference chat URL missing models/{id}.

Version/Branch

1.3.0-incubating-SNAPSHOT (main)

Commit Hash (Optional)

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What browsers are you seeing the problem on?

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Relevant log output

[PG1204]

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