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 serialization must keep the user-provided value — under 3.0 the client is built from self.http_client_kwargs at warm-up, losing the header. Keep the enriched kwargs on self.http_client_kwargs (so both 2.x init and 3.0 warm-up build the clients with the header) and store the original user-provided value as self._http_client_kwargs, which to_dict() serializes.

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

test_init_default/test_init_with_parameters: no longer assert on client attributes; they check component.api_key.resolve_value() and the other init attributes. Client creation is covered by a new dedicated test_warm_up (calls warm_up(), harmless on 2.x, required on 3.0).
test_init_fail_wo_api_key: runs init and warm_up() inside pytest.raises(ValueError), accepting the error from either version's raise point. The error message is identical on both. test_from_dict_fail_wo_env_var is removed as redundant with this test.
test_init_default_async → test_warm_up_async: async test 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)

Click to see where and how coverage changed

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
text_embedder.py
integrations/perplexity/src/haystack_integrations/components/generators/perplexity/chat
chat_generator.py
Project Total

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

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>

anakin87

I've left some general considerations on tests.

(I would probably have created separate PRs for each integration where we modify the source code.) Anyway, the important thing is releasing the integrations once merged to make them v3-ready)

…undant from_dict env-var tests - test_init_default/test_init_with_parameters no longer call warm_up(); they assert on api_key.resolve_value() instead of client attributes - client creation is covered by a new dedicated test_warm_up - test_from_dict_fail_wo_env_var removed (redundant with test_init_fail_wo_api_key) - test_init_default_async renamed to test_warm_up_async (it tests client creation) Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

…client_kwargs from an internal attribute Per review suggestion: keep the attribution-enriched http_client_kwargs on self.http_client_kwargs so haystack-ai >= 3.0 builds the clients with the header at warm-up, and store the original user-provided value under self._http_client_kwargs for to_dict(). Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

anakin87

I've also aligned the Perplexity Chat Generator in 1540d41 and be173b7

It's now ready to be merged

julian-risch mentioned this pull request Jul 2, 2026

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

Merged

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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anakin87 self-requested a review July 6, 2026 08:13

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julian-risch requested a review from anakin87 July 6, 2026 10:21

julian-risch and others added 3 commits July 6, 2026 15:49

standardize Perplexity Chat Generator

1540d41

fix tests

be173b7

anakin87 approved these changes Jul 6, 2026

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julian-risch merged commit a5907d1 into main Jul 6, 2026
78 of 84 checks passed

julian-risch deleted the fix/lazy-openai-client-compat branch July 6, 2026 15:34

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