# Review and engineering handoff: PRD v2 / SIM v2

Reviewers played `sim-v2.html` in their browsers. Every comment names the SIM scenario it refers to. An AI reviewer ran first and pre-filled items, which the humans then confirmed or dropped.

## Review feedback → changes (PRD 2.0 → 2.0.1, week 6)
| # | From | Scenario | Feedback | Change | Kind |
|---|---|---|---|---|---|
| R1 | AI reviewer | `handoff` | The code has no expiry. A screenshot of the code could be reused. | Code expires 10 min after issue; a new one is issued on check-in. | [AI] → [DECISION] Jo |
| R2 | Ravi (T&S) | `noshow` | No way to flag a bad experience privately. | New UC-9 *Report a problem*. | [DECISION] |
| R3 | Jo (platform) | `handoff` | Use the existing one-time code from Accounts, not a new service. | API table updated: `handoff.code.*` → Accounts OTC. | [FACT] → [DECISION] |
| R4 | Design | all | A 6-digit code is hard to read aloud. | Code shown as `482 · 913`, large type, with "read aloud" spacing. | [DECISION] |
| R5 | AI reviewer | `decline` | UC-3 doesn't say what happens to a held credit on decline. | Clarified: released immediately, event `swap.declined`. | [AI] |
| R6 | Ana | `spot` | What if no spot is within 2 areas? | Empty state "No Swap Spot near both of you" + *Suggest a spot* (UC-7 extended). | [DECISION] |
| R7 | Jo | `counter` | A counter-offer doubles the state machine. | Kept in the PRD and marked *build last*. | [REC] → see release (omitted) |

## Engineering handoff package (week 7)
- `05-prd-v2.md` (2.0.1), `sim-v2.html` (the reference behaviour; engineers use the **API log** and **Server state** panels), `06-decision-log.md`.
- **APIs still to define in engineering docs:** `spots.slots` (capacity model), `checkin.arrived` (geofence radius per venue).
- **Engineering's own docs:** a sequence diagram of the swap state machine and the event schema for the 6 events. These are linked back from the PRD; the PRD doesn't copy them.

## Design handoff
Design gets the SIM as the behaviour reference. The SIM's visuals are not the production design.
The *element rationale* (Inspect mode) explains which elements are required and which are only illustrative.