feat(perplexity): add X-Pplx-Integration attribution header

[jliounis]

Summary

• Add the X-Pplx-Integration: ag2/<version> default header to Perplexity SDK client construction for both AG2 Perplexity tools.
• Merge the attribution header with user-supplied SDK default_headers so existing client customization remains intact.
• Assert the Search API and chat-completions requests propagate the attribution header to the underlying HTTP client.

Motivation

The original Perplexity integration in #2752 added the tools but did not include this attribution header. The header lets Perplexity attribute Search API traffic back to AG2 through api-gateway logs and metrics. This is a no-op for users; it only adds an HTTP request header on Perplexity SDK calls.

Testing

• uv run pytest test/beta/tools/search/test_perplexity.py
• uv run ruff check autogen/beta/tools/search/perplexity.py test/beta/tools/search/test_perplexity.py
• uv run ruff format --check autogen/beta/tools/search/perplexity.py test/beta/tools/search/test_perplexity.py

Note: current main does not contain test/beta/tools/search/test_perplexity_search_api.py; the Perplexity Search API and chat-completions coverage is consolidated in test/beta/tools/search/test_perplexity.py.

---

🤖 Generated by PSI
🧠 Agent used: codex

[CLAassistant]

Thank you for your submission! We really appreciate it. Like many open source projects, we ask that you sign our Contributor License Agreement before we can accept your contribution.

---

james-pplx seems not to be a GitHub user. You need a GitHub account to be able to sign the CLA. If you have already a GitHub account, please add the email address used for this commit to your account.
_{You have signed the CLA already but the status is still pending? Let us recheck it.}

[Lancetnik]

Hi @jliounis, thanks for the contribution!

Before we can review or merge this PR, you need to sign our Contributor License Agreement — the license/cla check on this PR has the signing link. This applies to draft PRs as well: we don't want you to invest work into a change we can't accept.

Once the CLA is signed, the check turns green, the status:needs-cla label is removed, and the PR proceeds through the normal flow.

⏳ If the CLA isn't signed within 3 days, this PR will be marked stale and closed 7 days after that. Signing later and reopening is always an option.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

Files with missing lines	Coverage Δ
autogen/beta/tools/search/perplexity.py	99.00% <100.00%> (+0.05%)	⬆️

... and 41 files with indirect coverage changes

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.