feat: add Context.dev integration

[aadithyanr]

Related Issues

• related to New integration proposal: Context.dev #3872

Proposed Changes

Adds context-dev-haystack, an official Context.dev integration with three Haystack components:

• ContextWebSearch for relevance-ranked live web search
• ContextFetcher for fetching known URLs as Markdown Documents
• ContextCrawler for bounded website crawling

All components support sync and async execution, environment-backed secrets, Haystack serialization, retry handling, custom API parameters, and the production Context.dev API.

How did you test it?

• hatch run fmt-check
• hatch run test:types — 5 source files passed
• hatch run test:unit — 25 passed
• hatch run test:integration — 6 live production API tests passed across sync and async search, fetch, and crawl
• lowest-direct dependency resolution — 25 unit tests passed with haystack-ai==2.24.1 and httpx==0.27.0
• hatch build — sdist and wheel built successfully
• installed the wheel in a clean virtual environment and verified imports plus Haystack serialization round-trips

Notes for the reviewer

• The integration was scaffolded with scripts/create_new_integration.py.
• The distribution is named context-dev-haystack because the unrelated Context.ai project already owns context-haystack on PyPI.
• Crawling defaults to one page to avoid accidental credit consumption; callers can raise maxPages through crawl_params.
• Context.dev search accepts at least 10 results, so ContextWebSearch requests 10 when top_k is lower and returns only the requested number.
• The shared client normalizes boolean, list, and nested query parameters consistently for both Haystack sync and async HTTP paths.
• The unreleased Answers API is intentionally not included.
• The implementation was AI-assisted, then manually reviewed and validated against the live production API.

Checklist

• I have read the contributors guidelines and the code of conduct
• I opened and linked the required new integration proposal
• I added unit tests and updated the docstrings
• The PR title uses a conventional commit type

[CLAassistant]

All committers have signed the CLA.

[github-actions]

Hi @aadithyanr, thanks a lot for contributing a new integration! 🙏

This PR looks like it adds a new integration (context), but we couldn't
find a linked issue labeled new integration.

Every integration we merge is maintained, tested nightly, and released by us, so before reviewing the code
we'd like to understand the adoption of the technology you're integrating with. Could you please
open a New Integration Proposal
and fill it out? The Adoption signals section (GitHub stars, PyPI downloads over the last 30 days,
release activity, community demand) is what helps us decide whether to add the integration to Haystack.

Then reference the issue in this PR's description (for example, by adding Related to #<issue-number>)
and this comment will disappear automatically.

[HaystackBot]

Hi @aadithyanr, thanks a lot for your contribution! 🙏

We noticed that the Contributor License Agreement (CLA) check (license/cla) hasn't passed yet, so we've temporarily moved this PR to draft and paused the review assignment.

To get your PR reviewed, please sign the CLA via the link in the license/cla check below (or in the CLA bot comment). As soon as the check turns green, this PR will automatically be marked ready for review again and a reviewer will be re-assigned.

[HaystackBot]

Thanks for signing the CLA, @aadithyanr! 🎉 This PR is now ready for review again and the reviewer has been re-assigned.