feat: add SerpBase web search integration

[gefsikatsinelou]

Summary

Adds a new SerpBase web search integration (serpbase-haystack). SerpBaseWebSearch is a Haystack component that runs a Google web search through the SerpBase REST API and returns Document objects + links, matching the interface of the existing SerperDevWebSearch / TavilyWebSearch / SearchApiWebSearch components.

Background

Haystack already ships web search integrations for Serper, Tavily, SearchAPI, Brave and DDGS. SerpBase is a Google SERP API (Google Search, Images, News, Videos and Maps) aimed at a lower price point ($0.30/1k queries, no subscription). Adding it gives Haystack users another Google-results backend choice with the same component contract — drop-in replaceable via component.set() or YAML.

The integration follows the repo's established layout exactly: it was scaffolded with scripts/create_new_integration.py and mirrors the serperdev integration structure (component, tests, workflow, labeler, coverage workflow, root README inventory row).

Changes

• New: integrations/serpbase/ — full integration package
  • src/haystack_integrations/components/websearch/serpbase/websearch.py — SerpBaseWebSearch component (sync run + async run_async, to_dict/from_dict, domain filtering with allowed_domains/exclude_subdomains, optional search_params passthrough)
  • src/haystack_integrations/components/websearch/serpbase/__init__.py — exports SerpBaseWebSearch and SerpBaseError
  • tests/test_websearch.py — unit tests (mocked HTTP) + integration tests (skipped unless SERPBASE_API_KEY is set)
  • pyproject.toml, README.md, LICENSE.txt, pydoc/config_docusaurus.yml, py.typed
• New: .github/workflows/serpbase.yml — CI workflow mirroring the serperdev workflow
• Updated: .github/labeler.yml — integration:serpbase label rule
• Updated: .github/workflows/CI_coverage_comment.yml — register Test / serpbase
• Updated: README.md — serpbase row in the integration inventory table

Design decisions

Decision	Rationale
API key via SERPBASE_API_KEY env var / Secret	Follows existing convention (SERPERDEV_API_KEY, TAVILY_API_KEY, ...)
POST + X-API-Key header	SerpBase API contract (https://api.serpbase.dev/google/search)
Parses organic, featured_snippet, people_also_ask	Mirrors the SERP modules the serperdev component surfaces; Document.meta keeps rank/position/title/link
Same run/run_async signature + output types	Drop-in compatible with the other web search components
Domain filtering (allowed_domains, exclude_subdomains)	Same API surface as SerperDevWebSearch
No new dependencies	Uses httpx, already used by the other web search integrations

Testing

• Unit tests mock the HTTP layer and cover: top-k truncation (sync/async), missing-snippet handling, featured snippet + people-also-ask parsing, timeout → TimeoutError, HTTP/request errors → SerpBaseError, domain filtering.
• Integration tests run only when SERPBASE_API_KEY is set (skipped otherwise, same as serperdev).
• ruff and mypy pass on the integration (same config as the rest of the repo).

Notes for maintainers

• If you'd like the integration tests to run in CI, add a SERPBASE_API_KEY secret to the repo — the workflow already references it (tests skip gracefully when it's absent).
• Version tag will follow the integrations/serpbase-v* convention at release time.

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