The touring engine — one visit, a list of people, more than one home

Moved into the Leasing Engine hub on 2026-09-17. The whole design now lives in Leasing Engine — Technical Designs as section 17, with its own TL;DR and its architecture diagram at the top, and every section and appendix intact as subsections. This page is kept only so old links still work.

Where each former section went:

1. Architecture at a glance → 17.1
2. The invariant, and the five questions it hides → 17.2
3. Today, end to end → 17.3
4. The model: people own calendars, code owns choice → 17.4
5. Western Slope, the first case → 17.5
6. The schema, in Gera's shapes → 17.6
7. The resolver → 17.7
8. The heads-up rule → 17.8
9. The duration rule → 17.9
10. Two homes, one visit → 17.10
11. The pool: merge, share, or rotate → 17.11
12. Cover, reassignment, and the confirmation → 17.12
13. Lockbox / self-guided showing → 17.13
14. The double-book race → 17.14
15. Writing the visit back to the PMS → 17.15
16. What Camellia keeps, unchanged → 17.16
17. Presence and Orca → 17.17
18. The change ladder → 17.18
19. Decisions for Fede → 17.19
20. Risks → 17.20
A1 · decisions in full → 17.A1
A2 · Situs and Western Slope evidence → 17.A2
A3 · self-showing / lockbox comparison → 17.A3
A4 · file map and schema → 17.A4
A5 · open bugs and risks, in full → 17.A5
A6 · what every other product does → 17.A6
A7 · the change ladder, in full → 17.A7

All open calls from this page (D1–D11) are collected in the hub's Open decisions section.