docs(02-02): complete health probe service plan

- SUMMARY.md: 4 probers, 9 unit tests, nodemailer installed
- STATE.md: advanced to phase 2 plan 2, added 5 key decisions
- ROADMAP.md: updated phase 2 progress (2/4 summaries)
- REQUIREMENTS.md: marked HLTH-02 and HLTH-04 complete

.planning/STATE.md

@@ -5,33 +5,34 @@
 See: .planning/PROJECT.md (updated 2026-02-24)
 
 **Core value:** When something breaks — an API key expires, a service goes down, a credential needs reauthorization — the admin knows immediately and knows exactly what to fix.
-**Current focus:** Phase 1 — Data Foundation
+**Current focus:** Phase 2 — Backend Services
 
 ## Current Position
 
-Phase: 1 of 4 (Data Foundation)
+Phase: 2 of 4 (Backend Services)
 Plan: 2 of TBD in current phase
 Status: In progress
-Last activity: 2026-02-24 — Completed 01-02 (HealthCheckModel + AlertEventModel unit tests)
+Last activity: 2026-02-24 — Completed 02-02 (healthProbeService with 4 probers + 9 unit tests)
 
-Progress: [██░░░░░░░░] 20%
+Progress: [████░░░░░░] 40%
 
 ## Performance Metrics
 
 **Velocity:**
-- Total plans completed: 2
-- Average duration: ~17 min
-- Total execution time: ~0.57 hours
+- Total plans completed: 4
+- Average duration: ~18 min
+- Total execution time: ~1.2 hours
 
 **By Phase:**
 
 | Phase | Plans | Total | Avg/Plan |
 |-------|-------|-------|----------|
 | 01-data-foundation | 2 | ~34 min | ~17 min |
+| 02-backend-services | 2 | ~38 min | ~19 min |
 
 **Recent Trend:**
-- Last 5 plans: 01-01 (8 min), 01-02 (26 min)
-- Trend: —
+- Last 5 plans: 01-01 (8 min), 01-02 (26 min), 02-01 (20 min), 02-02 (18 min)
+- Trend: Stable ~18 min/plan
 
 *Updated after each plan completion*
 
@@ -53,6 +54,11 @@ Recent decisions affecting current work:
 - 01-02: Supabase mock uses chain.then (thenability) so both .single() and direct await patterns work from one mock
 - 01-02: makeSupabaseChain() factory per test — no shared mock state between tests
 - 01-02: vi.mock() factories must use only inline vi.fn() to avoid Vitest hoisting TDZ errors
+- 02-02: LLM probe uses claude-haiku-4-5 with max_tokens 5 (cheapest model, prevents expensive accidental probes)
+- 02-02: Supabase probe uses getPostgresPool().query('SELECT 1') not PostgREST (tests actual DB connectivity)
+- 02-02: Firebase Auth probe: verifyIdToken always throws; 'INVALID'/'Decoding'/'argument' in message = SDK alive = healthy
+- 02-02: Promise.allSettled for probe orchestration — all 4 probes run even if one throws outside its own try/catch
+- 02-02: Per-probe HealthCheckModel.create failure swallowed with logger.error — probe results still returned to caller
 
 ### Pending Todos
 
@@ -67,5 +73,5 @@ None yet.
 ## Session Continuity
 
 Last session: 2026-02-24
-Stopped at: Completed 01-02-PLAN.md — HealthCheckModel + AlertEventModel unit tests (33 tests passing)
+Stopped at: Completed 02-02-PLAN.md — healthProbeService with 4 probers + 9 unit tests (nodemailer installed)
 Resume file: None