fix: support Haystack 3.0's lazy OpenAI client initialization in OpenAI-inheriting generators by julian-risch · Pull Request #3536 · deepset-ai/haystack-core-integrations

julian-risch · 2026-07-02T12:29:30Z

Related Issues

Part of deepset-ai/haystack-private#446

Haystack 3.0 no longer creates the OpenAI clients in __init__: self.client/self.async_client are None until warm_up()/warm_up_async(), the _is_warmed_up flag is gone, and a missing API key raises at warm-up instead of at init. This breaks the ten integrations that subclass OpenAIChatGenerator/OpenAIGenerator/OpenAIResponsesChatGenerator/the OpenAI embedders.

Proposed Changes:

Source changes

mistral, openrouter (run/run_async overrides): replace the removed if not self._is_warmed_up: self.warm_up() with an unconditional self.warm_up() (idempotent on both versions); in run_async, call warm_up_async() when it exists (3.0) so the async client is created on the running event loop; narrow the now-Optional clients for mypy with the same assert-after-warm-up idiom that haystack 3.0's own run() uses.
perplexity chat generator: only wrap the clients with the Perplexity attribution headers in __init__ when they exist (2.x); add warm_up/warm_up_async overrides that apply the headers when 3.0 creates the clients.
perplexity embedders: the attribution header is injected via http_client_kwargs, but the serialized self.http_client_kwargs intentionally keeps the user-provided value — under 3.0 the client is built from that attribute at warm-up, losing the header. Add warm_up/warm_up_async overrides that swap the enriched kwargs in during client creation (no-ops on 2.x, which has no embedder warm-up and builds the client in __init__).

Test changes (aimlapi, cometapi, meta_llama, mistral, nvidia, openrouter, orcarouter, perplexity, stackit, togetherai)

test_init_default/test_init_with_parameters: call component.warm_up() before asserting on client attributes (harmless on 2.x, required on 3.0).
test_init_fail_wo_api_key/test_from_dict_fail_wo_env_var: run init/from_dict and warm_up() inside pytest.raises(ValueError), accepting the error from either version's raise point. The error message is identical on both.
test_init_default_async: converted to async tests that await component.warm_up_async() when available, since 3.0 only creates the async client there.

How did you test it?

Haystack 2.x: unit tests pass.
Haystack v3 branch (installed git+https://github.com/deepset-ai/haystack.git@v3 into the test envs; for the seven suites that also need the ToolInvoker import guard I verified on a local merge with test: guard ToolInvoker imports so chat-generator tests run under Haystack 3.0 #3535):
- test:types is clean in all ten — the _is_warmed_up/OpenAI | None mypy errors from the sweep are gone.
- All lazy-client test failures are fixed. The only remaining v3 unit failures are addressed in other opened PRs.

Notes for the reviewer

Checklist

I have read the contributors guidelines and the code of conduct
I have updated the related issue with new insights and changes
I added unit tests and updated the docstrings
I've used one of the conventional commit types for my PR title: fix:, feat:, build:, chore:, ci:, docs:, style:, refactor:, perf:, test:.

🤖 Generated with Claude Code

Haystack 3.0 no longer creates the OpenAI clients in __init__: they are None until warm_up()/warm_up_async(), and a missing API key raises at warm-up instead of init. Adapt the OpenAI-inheriting integrations while keeping 2.x behavior: - mistral, openrouter: replace the removed _is_warmed_up flag with an unconditional idempotent warm_up() (warm_up_async in run_async when available) and narrow the now-Optional clients for mypy. - perplexity: only wrap the clients with attribution headers in __init__ when they exist (2.x); override warm_up/warm_up_async to inject the headers when 3.0 creates the clients. - tests: warm the component up before asserting on client attributes and accept the API-key error from either __init__ (2.x) or warm_up (3.0). Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

github-actions · 2026-07-02T12:30:35Z

Coverage report (meta_llama)

This PR does not seem to contain any modification to coverable code.

github-actions · 2026-07-02T12:30:38Z

Coverage report (orcarouter)

This PR does not seem to contain any modification to coverable code.

github-actions · 2026-07-02T12:30:41Z

Coverage report (nvidia)

This PR does not seem to contain any modification to coverable code.

github-actions · 2026-07-02T12:30:43Z

Coverage report (openrouter)

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File	Statements	Missing	Coverage	Coverage (new stmts)	Lines missing
integrations/openrouter/src/haystack_integrations/components/generators/openrouter/chat
chat_generator.py					434
Project Total

_{This report was generated by python-coverage-comment-action}

github-actions · 2026-07-02T12:30:44Z

Coverage report (cometapi)

This PR does not seem to contain any modification to coverable code.

github-actions · 2026-07-02T12:30:45Z

Coverage report (stackit)

This PR does not seem to contain any modification to coverable code.

github-actions · 2026-07-02T12:30:46Z

Coverage report (togetherai)

This PR does not seem to contain any modification to coverable code.

github-actions · 2026-07-02T12:30:48Z

Coverage report (aimlapi)

This PR does not seem to contain any modification to coverable code.

github-actions · 2026-07-02T12:30:49Z

Coverage report (mistral)

Click to see where and how coverage changed

File	Statements	Missing	Coverage	Coverage (new stmts)	Lines missing
integrations/mistral/src/haystack_integrations/components/generators/mistral/chat
chat_generator.py					389-390, 432, 463-464
Project Total

_{This report was generated by python-coverage-comment-action}

…dder perplexity's ruff config forbids assert outside tests (S101); raise a RuntimeError instead when the client is missing, which narrows the Optional type for mypy just as well. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

github-actions · 2026-07-02T15:31:19Z

Coverage report (perplexity)

Click to see where and how coverage changed

File	Statements	Missing	Coverage	Coverage (new stmts)	Lines missing
integrations/perplexity/src/haystack_integrations/components/embedders/perplexity
document_embedder.py					157-166, 176-185
text_embedder.py					129-138, 148-157
integrations/perplexity/src/haystack_integrations/components/generators/perplexity/chat
chat_generator.py					153, 164-167
Project Total

_{This report was generated by python-coverage-comment-action}

sjrl · 2026-07-03T07:41:11Z

            max_retries=max_retries,
            http_client_kwargs=_http_client_kwargs_with_attribution(http_client_kwargs),
        )
        self.http_client_kwargs = http_client_kwargs


I wonder if instead of the new warm_up methods we should instead store the original user provided http_client_kwargs under a new key like self._http_client_kwargs = http_client_kwargs and then update the to_dict method to use this internal key.

Then I would set self.http_client_kwargs = _http_client_kwargs_with_attribution(http_client_kwargs) which would avoid the need for the new warm_up methods. WDYT?

Review feedback on #3536: drop the warm-up dev comments in run(), and replace the assert / raise-RuntimeError narrowing with type: ignore[union-attr] comments, consistent with how the repo usually silences mypy for attributes that are Optional only with haystack-ai >= 3.0. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

julian-risch mentioned this pull request Jul 2, 2026

test: trust test modules under Haystack 3.0's deserialization allowlist #3537

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julian-risch marked this pull request as ready for review July 2, 2026 15:22

julian-risch requested a review from a team as a code owner July 2, 2026 15:22

julian-risch requested review from sjrl and removed request for a team July 2, 2026 15:22

julian-risch mentioned this pull request Jul 3, 2026

test: make Tool/Agent serialization assertions version-agnostic for Haystack 2.x/3.x #3533

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sjrl reviewed Jul 3, 2026

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