D4.1 Database-authored events in DTC

Plan issue D4.1, phase 4 of the community-base unification plan.

Spec: docs/plan/phase-4.md, section D4.1, in DataTalksClub/community-base. Status is tracked in docs/plan/STATUS.md there, which stays the source of truth.

Depends on: C5.3. Do not start until every one of them is done in STATUS.md.

Process

This repository's AGENTS.md and _docs/PROCESS.md govern this work, with _docs/specs/ as the product authority. The plan says what to build and how to verify it; the site process says how work is done here.

Spec

Repository: DataTalksClub/website. Depends on: C5.3. Playbook P5 for events.

Read first

• events/models.py, events/identity.py, events/importers.py, events/qna/,
  events/services.py, _docs/specs/05-events-registration-email.md "Event model",
  _docs/architecture/event-qna-integration.md, _docs/compatibility/.

Steps

1. Export current events, Q&A sessions and historical aggregates (P5 step 1).
2. Create event_qna app: models from events/qna/ with session.event as a OneToOneField
   to events.Event (integer pk now); views and Studio pages unchanged otherwise.
   historical_registrations app for the aggregate models keyed by event_id.
3. Remove the events parser from the content sync; remove events/ app; install
   community_base.events with EVENT_URL_STYLE="public_id"; rebuild tables (P5 steps 2 to 4).
4. Import command: old Event rows -> shared Event with public_id preserved, slug
   preserved, speakers -> Host(kind=speaker, external_ref=<people short>), lifecycle mapped to
   status; Q&A sessions and aggregates re-linked by public_id.
5. Studio: DTC event pages come from the package; Q&A and historical totals register under the
   Events section.
6. Public detail keeps speaker links through HOST_PROFILE_RESOLVER; description bridge from
   _docs/event-description-bridge.md becomes the description field content.

Verification

• Row counts before and after import equal for events, Q&A sessions, aggregates.
• uv run pytest events event_qna historical_registrations -q -> pass; compatibility route
  test passes; Playwright core events tests pass.

First confirm C5.3 is done in docs/plan/STATUS.md, then read AGENTS.md, _docs/PROCESS.md, docs/plan/phase-4.md, and the listed events files and specifications. Trace the existing Event, Q&A, importer, and service models before planning the event_qna and historical_registrations apps and import. Done means the migration preserves row counts and identifiers, the listed pytest and compatibility tests pass, and the core Playwright events tests pass.