docs(33): capture phase context

.planning/phases/33-currency-system/33-DISCUSSION-LOG.md

@@ -0,0 +1,138 @@
+# Phase 33: Currency System - Discussion Log
+
+> **Audit trail only.** Do not use as input to planning, research, or execution agents.
+> Decisions are captured in CONTEXT.md — this log preserves the alternatives considered.
+
+**Date:** 2026-04-13
+**Phase:** 33-Currency System
+**Areas discussed:** Data model & source currency, Conversion strategy, User experience & display, Catalog & sharing implications
+
+---
+
+## Data Model & Source Currency
+
+### Core pricing model
+
+| Option | Description | Selected |
+|--------|-------------|----------|
+| Per-item source currency | Add priceCurrency column alongside priceCents | |
+| Per-user base currency only | All prices assumed in user's currency | |
+| Everything stored as USD | Normalize to USD on entry | |
+| Market-specific pricing | Prices are market-specific, not converted. Different markets have different UVP/MSRP | ✓ |
+
+**User's choice:** Market-specific pricing — not just exchange rate conversion. A €2,000 bike in Germany may be £2,200 in the UK because that's the UK market price, not a conversion.
+**Notes:** User emphasized that German UVP (MSRP) can be completely different from UK or US retail prices. This is a market reality, not a conversion problem.
+
+### Community price data
+
+| Option | Description | Selected |
+|--------|-------------|----------|
+| On catalog detail page | "Report your price" button | |
+| During add-to-collection | Capture when adding item | |
+| Both (tied to ownership) | Only report for items you own, auto-captured from collection | ✓ |
+
+**User's choice:** Both, but tied to collection ownership — you can only report prices for items you have. Prevents duplicates.
+**Notes:** User also identified that candidate "price I found it for" is research-quality data. Purchase date should be tracked for temporal context.
+
+### Scope check
+
+| Option | Description | Selected |
+|--------|-------------|----------|
+| Foundation layer | UVP display + conversion, community data later | |
+| Full system | Everything: market prices, community submissions, conversion | ✓ |
+| Let's scope it together | Walk through each piece | |
+
+**User's choice:** Full system in Phase 33.
+
+---
+
+## Conversion Strategy
+
+### Rate source
+
+| Option | Description | Selected |
+|--------|-------------|----------|
+| Free API (ECB/frankfurter.app) | Daily rates, no API key, ~30 currencies | ✓ |
+| Paid API (Open Exchange Rates) | More currencies, intraday, ~$12/mo | |
+| You decide | Claude picks | |
+
+**User's choice:** Free API — ECB via frankfurter.app
+
+### Conversion location
+
+| Option | Description | Selected |
+|--------|-------------|----------|
+| Server-side | Server fetches rates, returns converted prices | ✓ |
+| Client-side | Client converts locally | |
+| You decide | Claude picks | |
+
+**User's choice:** Server-side
+
+---
+
+## User Experience & Display
+
+### Market/locale detection
+
+| Option | Description | Selected |
+|--------|-------------|----------|
+| Manual setting only | User picks market in settings | |
+| Auto-detect + manual override | Browser locale / IP, changeable | |
+| Tied to currency choice | Currency = market, with auto-suggestion | ✓ |
+
+**User's choice:** Currency tied to market (EUR=EU, GBP=UK, USD=US) with auto-suggestion from browser locale and IP geolocation. Best of both worlds.
+
+### Converted price display
+
+| Option | Description | Selected |
+|--------|-------------|----------|
+| Prefix with ~ and muted style | ~£1,720 with tooltip | |
+| Dual display | €2,000 (~£1,720) — source prominent, converted in parens | ✓ |
+| You decide | Claude picks | |
+
+**User's choice:** Dual display
+
+---
+
+## Catalog & Sharing Implications
+
+### Catalog detail page
+
+| Option | Description | Selected |
+|--------|-------------|----------|
+| User's market first, others expandable | Local UVP + community avg prominent, other markets collapsible | ✓ |
+| All markets in a table | Price table showing all markets at once | |
+| You decide | Claude picks | |
+
+**User's choice:** User's market first, others expandable
+
+### Shared setup prices
+
+| Option | Description | Selected |
+|--------|-------------|----------|
+| Owner's original prices | Show in owner's currency with conversion toggle | |
+| Viewer's market prices | Auto-convert to viewer's currency | |
+| Layered disclosure | Card: viewer's market MSRP. Detail: full breakdown including owner's price | ✓ |
+
+**User's choice:** Layered — card shows viewer's market MSRP, detail page shows full breakdown (owner's price, all market MSRPs, community averages).
+
+### Comparison table currencies
+
+| Option | Description | Selected |
+|--------|-------------|----------|
+| Normalize to user's currency | All candidates in viewer's currency, marked as approximate | ✓ |
+| Source currency with tooltip | Each in source currency, hover for conversion | |
+| You decide | Claude picks | |
+
+**User's choice:** Normalize — mixed currencies (EUR, USD, JPY, TRY) are useless for comparison. Rough converted price gives direction even if not exact. Users can add their own researched "price I found it for."
+
+## Claude's Discretion
+
+- Rate caching strategy
+- Schema design for market prices table
+- Community price aggregation approach
+- Transition from current simple priceCents model
+
+## Deferred Ideas
+
+None — discussion stayed within phase scope.