Implement Garmin biometric fetching functions (P2.1)

Add specific fetchers for HRV, Body Battery, and Intensity Minutes
to enable real biometric data collection from Garmin Connect API.

Functions added:
- fetchHrvStatus(): Returns "Balanced", "Unbalanced", or "Unknown"
- fetchBodyBattery(): Returns current BB and yesterday's low value
- fetchIntensityMinutes(): Returns 7-day rolling sum of activity

All functions gracefully handle API failures with safe defaults.
Test count expanded from 14 to 33 covering all scenarios.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

IMPLEMENTATION_PLAN.md

@@ -13,7 +13,7 @@ This file is maintained by Ralph. Run `./ralph-sandbox.sh plan 3` to generate ta
 | `ics.ts` | **COMPLETE** | 23 tests covering generateIcsFeed (90 days of phase events), ICS format validation, timezone handling |
 | `encryption.ts` | **COMPLETE** | 14 tests covering AES-256-GCM encrypt/decrypt round-trip, error handling, key validation |
 | `decision-engine.ts` | **COMPLETE** | 8 priority rules + override handling with `getDecisionWithOverrides()`, 24 tests |
-| `garmin.ts` | **COMPLETE** | 14 tests covering fetchGarminData, isTokenExpired, daysUntilExpiry, error handling, token validation |
+| `garmin.ts` | **COMPLETE** | 33 tests covering fetchGarminData, fetchHrvStatus, fetchBodyBattery, fetchIntensityMinutes, isTokenExpired, daysUntilExpiry, error handling, token validation |
 | `pocketbase.ts` | **COMPLETE** | 9 tests covering `createPocketBaseClient()`, `isAuthenticated()`, `getCurrentUser()`, `loadAuthFromCookies()` |
 | `auth-middleware.ts` | **COMPLETE** | 6 tests covering `withAuth()` wrapper for API route protection |
 | `middleware.ts` (Next.js) | **COMPLETE** | 12 tests covering page protection, redirects to login |
@@ -81,7 +81,7 @@ This file is maintained by Ralph. Run `./ralph-sandbox.sh plan 3` to generate ta
 | `src/lib/email.test.ts` | **EXISTS** - 14 tests (email content, subject lines, formatting) |
 | `src/lib/ics.test.ts` | **EXISTS** - 23 tests (ICS format validation, 90-day event generation, timezone handling) |
 | `src/lib/encryption.test.ts` | **EXISTS** - 14 tests (encrypt/decrypt round-trip, error handling, key validation) |
-| `src/lib/garmin.test.ts` | **EXISTS** - 14 tests (API calls, token expiry, error handling) |
+| `src/lib/garmin.test.ts` | **EXISTS** - 33 tests (fetchGarminData, fetchHrvStatus, fetchBodyBattery, fetchIntensityMinutes, token expiry, error handling) |
 | E2E tests | **NONE** |
 
 ### Critical Business Rules (from Spec)
@@ -248,14 +248,17 @@ Minimum viable product - app can be used for daily decisions.
 
 Full feature set for production use.
 
-### P2.1: Garmin Data Fetching Functions
-- [ ] Add specific fetchers for HRV, Body Battery, Intensity Minutes
+### P2.1: Garmin Data Fetching Functions ✅ COMPLETE
+- [x] Add specific fetchers for HRV, Body Battery, Intensity Minutes
 - **Files:**
-  - `src/lib/garmin.ts` - Add `fetchHrvStatus()`, `fetchBodyBattery()`, `fetchIntensityMinutes()`
+  - `src/lib/garmin.ts` - Added `fetchHrvStatus()`, `fetchBodyBattery()`, `fetchIntensityMinutes()`
 - **Tests:**
-  - `src/lib/garmin.test.ts` - Test API calls, response parsing, error handling
+  - `src/lib/garmin.test.ts` - 33 tests covering API calls, response parsing, error handling (increased from 14 tests)
+- **Functions Implemented:**
+  - `fetchHrvStatus()` - Fetches HRV status (balanced/unbalanced) from Garmin
+  - `fetchBodyBattery()` - Fetches current and yesterday's low body battery values
+  - `fetchIntensityMinutes()` - Fetches weekly moderate + vigorous intensity minutes
 - **Why:** Real biometric data is required for accurate decisions
-- **Note:** Currently only has generic fetchGarminData, isTokenExpired, daysUntilExpiry
 
 ### P2.2: POST/DELETE /api/garmin/tokens Implementation
 - [ ] Store encrypted Garmin OAuth tokens
@@ -442,12 +445,13 @@ Testing, error handling, and refinements.
 ### P3.6: Garmin Tests ✅ COMPLETE
 - [x] Unit tests for Garmin API interactions
 - **Files:**
-  - `src/lib/garmin.test.ts` - 14 tests covering API calls, error handling, token expiry
+  - `src/lib/garmin.test.ts` - 33 tests covering API calls, error handling, token expiry (expanded in P2.1)
 - **Test Cases Covered:**
-  - fetchGarminData HTTP calls and response parsing
+  - fetchGarminData, fetchHrvStatus, fetchBodyBattery, fetchIntensityMinutes HTTP calls and response parsing
   - isTokenExpired logic with various expiry dates
   - daysUntilExpiry calculations
   - Error handling for invalid tokens and network failures
+  - Response parsing for biometric data structures
 - **Why:** External API integration robustness is now fully tested
 
 ### P3.7: Error Handling Improvements
@@ -532,7 +536,7 @@ P2.14 Mini calendar
 - [x] **email.ts** - Complete with 14 tests (`sendDailyEmail`, `sendPeriodConfirmationEmail`, email formatting) (P3.3)
 - [x] **ics.ts** - Complete with 23 tests (`generateIcsFeed`, ICS format validation, 90-day event generation) (P3.4)
 - [x] **encryption.ts** - Complete with 14 tests (AES-256-GCM encrypt/decrypt, round-trip validation, error handling) (P3.5)
-- [x] **garmin.ts** - Complete with 14 tests (`fetchGarminData`, `isTokenExpired`, `daysUntilExpiry`, error handling) (P3.6)
+- [x] **garmin.ts** - Complete with 33 tests (`fetchGarminData`, `fetchHrvStatus`, `fetchBodyBattery`, `fetchIntensityMinutes`, `isTokenExpired`, `daysUntilExpiry`, error handling) (P2.1, P3.6)
 
 ### Components
 - [x] **DecisionCard** - Displays decision status, icon, and reason
@@ -565,7 +569,7 @@ P2.14 Mini calendar
 
 - [x] ~~`src/lib/auth-middleware.ts` does not exist~~ - CREATED in P0.2
 - [x] ~~`src/middleware.ts` does not exist~~ - CREATED in P0.2
-- [ ] `garmin.ts` is only ~30% complete - missing specific biometric fetchers
+- [x] ~~`garmin.ts` is only ~30% complete - missing specific biometric fetchers~~ - FIXED in P2.1 (added fetchHrvStatus, fetchBodyBattery, fetchIntensityMinutes)
 - [x] ~~`pocketbase.ts` missing all auth helper functions~~ - FIXED in P0.1
 - [x] ~~`src/app/api/today/route.ts` type error with null body battery values~~ - FIXED (added null coalescing)