docs(27): update state after phase completion

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: baotoq

.planning/STATE.md

@@ -9,27 +9,27 @@
 See: .planning/PROJECT.md (updated 2026-02-20)
 
 **Core value:** Single view of all investments (crypto, ETF, savings) with real P&L, plus automated BTC DCA
-**Current focus:** Phase 27 — Price Feeds & Market Data
+**Current focus:** Phase 28 — Portfolio API Endpoints
 
 ## Current Position
 
-Phase: 27 of 29 (Price Feeds & Market Data)
-Plan: 0 of TBD
-Status: Ready to plan
-Last activity: 2026-02-20 — Phase 26 complete (3 plans, 7 entities, 14 new tests)
+Phase: 27 of 29 (Price Feeds & Market Data) — COMPLETE
+Plan: 2 of 2 (all executed)
+Status: Phase 27 complete
+Last activity: 2026-02-20 — Phase 27 complete (2 plans, 3 providers, 11 new files)
 
-Progress: [##░░░░░░░░] 25% (v4.0)
+Progress: [#####░░░░░] 50% (v4.0)
 
 ## Performance Metrics
 
 **Velocity:**
-- Total plans completed: 59 (across v1.0-v4.0)
+- Total plans completed: 61 (across v1.0-v4.0)
 - v1.0: 1 day (11 plans)
 - v1.1: 1 day (7 plans)
 - v1.2: 2 days (12 plans)
 - v2.0: 2 days (15 plans)
 - v3.0: 1 day (11 plans)
-- v4.0: in progress (3 plans so far)
+- v4.0: in progress (5 plans so far)
 
 **By Milestone:**
 
@@ -40,7 +40,7 @@ Progress: [##░░░░░░░░] 25% (v4.0)
 | v1.2 | 9-12 | 12 | Complete |
 | v2.0 | 13-19 | 15 | Complete |
 | v3.0 | 20-25 | 11 | Complete |
-| v4.0 | 26-29 | 3/TBD | Phase 26 complete |
+| v4.0 | 26-29 | 5/TBD | Phase 27 complete |
 
 ## Accumulated Context
 
@@ -63,6 +63,15 @@ All decisions logged in PROJECT.md Key Decisions table.
 - Compound interest test tolerance: 500 VND on 10M deposits (double-precision variance from Math.Pow)
 - VND Principal: numeric(18,0); Crypto Quantity: numeric(18,8); Fee: numeric(18,2); Rate: numeric(8,6)
 
+**Phase 27 decisions:**
+- VNDirect dchart-api used instead of finfo-api (finfo times out externally, dchart verified live)
+- PriceFeedEntry uses positional record with long FetchedAtUnixSeconds (avoids MessagePack DateTimeOffset resolver issues)
+- VNDirect ETF provider uses stale-while-revalidate (returns stale immediately, fire-and-forget refresh)
+- OpenErApi exchange rate uses wait-for-fetch (accuracy matters more for currency conversion)
+- CoinGecko API key added as DefaultRequestHeader on HttpClient at DI registration time
+- Shared resilience config: 2 retries, 1s exponential backoff, 15s total/8s attempt timeout
+- VNDirect close prices multiplied by 1000 to convert from thousands-of-VND to actual VND
+
 **v3.0 Flutter conventions carried forward:**
 - Dark-only theme, NavigationBar (Material 3) + CupertinoIcons, StatefulShellRoute
 - Manual fromJson for DTO models (no json_serializable), intl as explicit dependency
@@ -71,7 +80,7 @@ All decisions logged in PROJECT.md Key Decisions table.
 
 ### Known Risks
 
-- Phase 27: VNDirect finfo API JSON schema unconfirmed (endpoint timed out during research). Needs live request verification at Phase 27 planning start. Use `/gsd:research-phase` before planning Phase 27.
+- VNDirect dchart-api is undocumented/unofficial — could change without notice (research valid until 2026-03-20)
 
 ### Pending Todos
 
@@ -84,8 +93,8 @@ v4.0 roadmap: 4 phases (26-29), 20 requirements, all mapped.
 ## Session Continuity
 
 Last session: 2026-02-20
-Stopped at: Phase 26 complete — all 3 plans executed (domain models, interest calculator, EF Core persistence)
-Next step: `/gsd:research-phase 27` (verify VNDirect API before planning)
+Stopped at: Phase 27 complete — all 2 plans executed (shared types + CoinGecko provider, VNDirect + exchange rate + DI wiring)
+Next step: `/gsd:plan-phase 28` (Portfolio API Endpoints)
 
 ---
-*State updated: 2026-02-20 after Phase 26 completion*
+*State updated: 2026-02-20 after Phase 27 completion*

.planning/phases/27-price-feed-infrastructure/27-01-SUMMARY.md

@@ -0,0 +1,48 @@
+# Phase 27 Plan 01 — Summary
+
+**Completed:** 2026-02-20
+**Duration:** Single pass, zero errors
+
+## What Was Built
+
+Created the shared price feed infrastructure and CoinGecko crypto price provider:
+
+1. **PriceFeedEntry** — MessagePack-serializable positional record with `Price`, `FetchedAtUnixSeconds`, `Currency`. Uses `long` for timestamp to avoid DateTimeOffset resolver issues. Computed `FetchedAt` property via `[IgnoreMember]`.
+
+2. **PriceFeedResult** — Return type record with `Price`, `FetchedAt`, `IsStale`, `Currency`. Static factories `Fresh()` and `Stale()` for clarity.
+
+3. **ICryptoPriceProvider** — Interface with `GetPriceAsync(string coinGeckoId)` and batch `GetPricesAsync(IEnumerable<string> coinGeckoIds)`.
+
+4. **IEtfPriceProvider** — Interface with `GetPriceAsync(string vnDirectTicker)`.
+
+5. **IExchangeRateProvider** — Interface with `GetUsdToVndRateAsync()`.
+
+6. **CoinGeckoPriceProvider** — Full implementation with:
+   - 5-minute freshness window, 30-day physical Redis TTL
+   - Lazy fetch: fresh cache returns immediately, stale attempts refresh with fallback, empty cache blocks
+   - Batch API call via `/simple/price?ids={csv}&vs_currencies=usd`
+   - Optional `x-cg-demo-api-key` header from CoinGeckoOptions.ApiKey
+   - Primary constructor with HttpClient, IDistributedCache, IOptionsMonitor, ILogger
+
+## Files Created
+
+| File | Purpose |
+|------|---------|
+| `Infrastructure/PriceFeeds/PriceFeedEntry.cs` | MessagePack cache record |
+| `Infrastructure/PriceFeeds/PriceFeedResult.cs` | Provider return type |
+| `Infrastructure/PriceFeeds/Crypto/ICryptoPriceProvider.cs` | Crypto provider interface |
+| `Infrastructure/PriceFeeds/Crypto/CoinGeckoPriceProvider.cs` | CoinGecko implementation |
+| `Infrastructure/PriceFeeds/Etf/IEtfPriceProvider.cs` | ETF provider interface |
+| `Infrastructure/PriceFeeds/ExchangeRate/IExchangeRateProvider.cs` | Exchange rate interface |
+
+## Verification
+
+- `dotnet build TradingBot.slnx` — 0 errors
+- All MessagePack attributes correctly applied (MsgPack017 warning resolved with positional record)
+- No new NuGet packages required
+
+## Decisions Made
+
+- Used positional record syntax for PriceFeedEntry to avoid MessagePack init accessor warnings
+- CoinGecko API key sent per-request via HttpRequestMessage header (not default header on HttpClient — that's handled in ServiceCollectionExtensions in Plan 02)
+- Batch method returns stale results for cached IDs and throws only if uncached IDs fail to fetch

.planning/phases/27-price-feed-infrastructure/27-02-SUMMARY.md

@@ -0,0 +1,58 @@
+# Phase 27 Plan 02 — Summary
+
+**Completed:** 2026-02-20
+**Duration:** Single pass, zero errors
+
+## What Was Built
+
+Completed the price feed infrastructure with VNDirect ETF provider, exchange rate provider, DI wiring, and Program.cs integration:
+
+1. **VNDirectPriceProvider** — Stale-while-revalidate pattern:
+   - Fresh cache (< 48h) returns immediately
+   - Stale cache returns immediately + fire-and-forget background refresh via `_ = RefreshInBackgroundAsync()`
+   - Empty cache blocks on fetch, throws if API is down
+   - Close prices multiplied by 1000 (dchart returns thousands-of-VND)
+   - Uses `CancellationToken.None` for background refresh (not tied to original request)
+
+2. **VNDirectDchartResponse** — JSON DTO for dchart API array format (`t`, `c`, `o`, `h`, `l`, `v`, `s`).
+
+3. **OpenErApiProvider** — Wait-for-fetch pattern (not stale-while-revalidate):
+   - Fresh cache (< 12h) returns immediately
+   - Stale cache tries refresh, falls back to stale on failure
+   - Empty cache blocks, throws if API is down
+   - Fetches from `v6/latest/USD`, extracts VND rate
+
+4. **OpenErApiResponse** — JSON DTO for exchange rate response.
+
+5. **ServiceCollectionExtensions.AddPriceFeeds()** — Wires all three providers:
+   - CoinGeckoPriceProvider HttpClient (api.coingecko.com, optional x-cg-demo-api-key header)
+   - VNDirectPriceProvider HttpClient (dchart-api.vndirect.com.vn)
+   - OpenErApiProvider HttpClient (open.er-api.com)
+   - Shared resilience config: 2 retries, 1s exponential backoff, 15s total timeout, 8s attempt timeout
+   - All registered as Scoped (matching existing DI patterns)
+
+6. **Program.cs** — Added `builder.Services.AddPriceFeeds(builder.Configuration)` after CoinGecko registration.
+
+## Files Created/Modified
+
+| File | Action |
+|------|--------|
+| `Infrastructure/PriceFeeds/Etf/VNDirectPriceProvider.cs` | Created |
+| `Infrastructure/PriceFeeds/Etf/VNDirectDchartResponse.cs` | Created |
+| `Infrastructure/PriceFeeds/ExchangeRate/OpenErApiProvider.cs` | Created |
+| `Infrastructure/PriceFeeds/ExchangeRate/OpenErApiResponse.cs` | Created |
+| `Infrastructure/PriceFeeds/ServiceCollectionExtensions.cs` | Created |
+| `Program.cs` | Modified (added using + AddPriceFeeds call) |
+
+## Verification
+
+- `dotnet build TradingBot.slnx` — 0 errors
+- `dotnet test` — 76/76 passed (all existing tests unchanged)
+- No new NuGet packages required
+
+## Decisions Made
+
+- VNDirect uses stale-while-revalidate (returns stale immediately, refreshes in background) per research recommendation — 48h TTL means staleness only during VN market hours
+- OpenErApiProvider uses wait-for-fetch (not stale-while-revalidate) — exchange rate accuracy matters more for currency conversion
+- Shared `ConfigureResilience` method avoids repeating resilience options 3 times
+- CoinGecko API key added as DefaultRequestHeader on HttpClient at registration time (ServiceCollectionExtensions), not per-request