feat: add olostep-haystack integration (WebSearch + Fetcher)

[umerkay]

Related Issues

• No related issue this is a new integration contribution

Proposed Changes:

Adds olostep-haystack, a new integration providing two components:

OlostepWebSearch searches the web using Olostep's /v1/searches
endpoint and returns results as Haystack Document objects (with title
and link in metadata) plus a list of URLs. Works as a drop-in alternative
to BraveSearchWebSearch and SerperDevWebSearch. Calls the REST endpoint
directly via requests (the Olostep Python SDK does not expose a searches
namespace).

OlostepFetcher fetches and converts web pages to clean Markdown (or
HTML) using the official olostep Python SDK (SyncOlostepClient). Returns
content as Haystack Document objects. Works as a drop-in alternative to
LinkContentFetcher + Firecrawl in web RAG pipelines.

Both components:

• Read the API key via Haystack's Secret (env var OLOSTEP_API_KEY)
• Support to_dict() / from_dict() for pipeline serialization
• Follow the same structure as brave-haystack

How did you test it?

• Unit tests for OlostepWebSearch mock requests.post and verify correct
  Document output, top_k limiting, allowed_domains filtering, missing
  API key error handling, and to_dict/from_dict round-trip
• Unit tests for OlostepFetcher mock SyncOlostepClient and verify correct
  Document output, None content handling, auth error propagation, and
  to_dict/from_dict round-trip
• Ran hatch run fmt, hatch run test:types, hatch run test:unit — all pass

Notes for the reviewer

• /v1/searches has no SDK wrapper requests.post is intentional, not an
  oversight
• SyncOlostepClient is imported inside run() rather than at module level
  to avoid import errors for users who haven't installed olostep
• The SDK requires Python 3.11+ which is reflected in pyproject.toml
• Olostep docs: https://docs.olostep.com

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: feat:

[CLAassistant]

All committers have signed the CLA.

[socket-security]

Review the following changes in direct dependencies. Learn more about Socket for GitHub.

Diff	Package	Supply Chain Security	Vulnerability	Quality	Maintenance	License
	olostep@​1.1.0

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[julian-risch]

Thank you for your suggestion and opening this issue. We recommend to publish and release this integration yourself using our repository template if you believe it benefits a larger group of users. https://github.com/deepset-ai/custom-component
Once you released it, your integration can be added to https://github.com/deepset-ai/haystack-integrations so that it gets listed on our web page https://haystack.deepset.ai/integrations