feat: get_seller_listings — list another seller's other listings

[asklepios-png]

Summary

Adds get_seller_listings(ad_id) — list the other active listings by the same seller as a given ad. This completes the "who else is this seller selling?" flow that began with owner_id extraction from the adview meta block.

How the endpoint was found

The seller-listings gateway endpoint is not visible from the website — the public profile page is fully server-rendered (the browser never sees the upstream call, and there's no client-side JSON endpoint). It was captured from the Android app's own traffic (emulator + HTTP Toolkit TLS interception):

GET /org/SEARCH_ID_BAP_COMMON?client=…&orgId={ownerId}&include_anonymous=false&page={n}
    host:            apps-gw-poc.svc.tori.fi
    finn-gw-service: SEARCH-QUEST-RC          (no X-Client-Id header needed)
    response:        { "docs": [ … ], "metadata": { "paging": { "param": "page", "current", "last" } } }

Key points that made this small:

• orgId is exactly the ownerId already carried in an adview's meta block, so listings.owner(ad_id) feeds straight in — no new identifier needed.
• It uses the same SEARCH-QUEST-RC service and BAP search key as the public search, so the existing finn-gw-key signing works unchanged — no changes to _request.
• The response shape matches the public search docs, so mapping is trivial.

Changes

• listings.seller_ads(owner_id, max_results=None) — paginates via the page param until metadata.paging.last
• MCP tool get_seller_listings(ad_id) — resolves owner → seller_ads → compact list
• tests/test_seller_ads.py — 4 tests (mock client, no network): single page, pagination, max_results cap, empty seller
• Docs: README tool table + library usage example

Verification

• Full test suite green (13/13)
• Live-verified against a real seller: owner(ad_id) → owner_id → 28 listings returned, titles and prices matching the app

🤖 Generated with Claude Code

[asklepios-png]

Personal note: this one scratches an itch I've been chasing for weeks — reliably pulling up another seller's other listings from just one of their ads. I'd tried a few dead ends (a profile-API path that always 404'd, the SSR web profile with no JSON endpoint, a headless SPiD session that needed OTP) before capturing the app's actual traffic finally revealed it was hiding in the search family all along (/org/{searchKey}?orgId=). Really happy it works end to end now. Glad to adjust anything for your review.