fix!: switch DALLEImageGenerator to gpt-image-2

[anakin87]

Related Issues

• fixes Dall-E models have been retired -> DALLEImageGenerator does not work #11318

Proposed Changes:

• switch DALLEImageGenerator to gpt-image-2, adapt for API changes but trying to keep backward compatibility

How did you test it?

CI, new (slow) integration test

Checklist

• I have read the contributors guidelines and the code of conduct.
• I have updated the related issue with new insights and changes.
• I have 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: and added ! in case the PR includes breaking changes.
• I have documented my code.
• I have added a release note file, following the contributors guidelines.
• I have run pre-commit hooks and fixed any issue.

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Project	Deployment	Actions	Updated (UTC)
haystack-docs	Ready	Preview, Comment	May 15, 2026 10:06am

[github-actions]

Coverage report

Click to see where and how coverage changed

File	Statements	Missing	Coverage	Coverage (new stmts)	Lines missing
haystack/components/generators
openai_dalle.py
haystack/core/pipeline
async_pipeline.py
Project Total

This report was generated by python-coverage-comment-action

[claude]

Code review

Checked for bugs and CLAUDE.md compliance. One issue found:

assert self.client without explanation — haystack/components/generators/openai_dalle.py line 127 (link)

AGENTS.md states: "To fix type issues, avoid type: ignore, casts, or assertions when possible. If they are necessary, explain why." (AGENTS.md L46-L50).

The new assert self.client replaces the prior # type: ignore[union-attr] but lacks an inline rationale. Other comparable type-narrowing assertions in this codebase consistently include a brief comment explaining why mypy needs the hint. Consider adding an explanatory comment, e.g.:

assert self.client is not None  # warm_up() sets self.client; hint for mypy

[bogdankostic]

Looking good, I'm just wondering if at some point we should also rename the component to something like OpenAIImageGenerator.

[anakin87]

Looking good, I'm just wondering if at some point we should also rename the component to something like OpenAIImageGenerator.

Noted for Haystack 3 on Notion