Fix: Attest the gadget-installs tile from the on-wiki install revision

Nik Gkountasrequested to merge
fix/T433621-gadget-installs-ledger into main

The /impact "Install gadgets" tile counted distinct wikis with an install_gadget cta_click carrying cta='install-success'. Those outcome ctas only exist since 2026-07-30, so every install before then — the entire real-user history — was invisible and the tile showed 0 since launch; the only install-success event ever recorded came from an excluded admin on a local dev wiki.

Mirrors the infobox-imports re-sourcing (!163 (merged)):

  • Headline count: COUNT(DISTINCT wiki_url) over task_verifications rows with task_key='install-gadget', windowed on verified_at, composing the shared excludeWikiSQL/excludeAdminsSQL production exclusions.
  • Drill-down: same predicates, GROUP BY wiki_url with MIN(verified_at) as ts, so pre-cta installs date correctly. The MediaWiki:Common.js artifact link (and the Gadgets-definition review note) are unchanged.

The ledger (in-flow credit + T433014 backfill) carries the whole install history with real on-wiki verification timestamps, so the tile windows truthfully across the pre-cta era. Verified against a prod DB copy: production-mode 90d/365d count = 1 (kai.wikipedia.org, ts 2026-06-25 10:36:48 from the backfill row), 30d = 0 (correctly out of window), and headline == drill-down row count at every window.

Known trade-off (accepted): a ledger row proves a verified run, so a wiki where the gadget was installed but never used does not count.

Co-Authored-By: Claude Fable 5 Bug: T433621

Closes T433621

Merge request reports