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+---
+phase: 8
+slug: backend-aggregation-filtering
+status: draft
+nyquist_compliant: false
+wave_0_complete: false
+created: 2026-04-09
+---
+
+# Phase 8 — Validation Strategy
+
+> Per-phase validation contract for feedback sampling during execution.
+
+---
+
+## Test Infrastructure
+
+| Property | Value |
+|----------|-------|
+| **Framework** | PHPUnit 10.x |
+| **Config file** | phpunit.xml.dist |
+| **Quick run command** | `vendor/bin/phpunit --filter HeatmapControllerTest` |
+| **Full suite command** | `vendor/bin/phpunit` |
+| **Estimated runtime** | ~5 seconds |
+
+---
+
+## Sampling Rate
+
+- **After every task commit:** Run `vendor/bin/phpunit --filter HeatmapControllerTest`
+- **After every plan wave:** Run `vendor/bin/phpunit`
+- **Before `/gsd-verify-work`:** Full suite must be green
+- **Max feedback latency:** 5 seconds
+
+---
+
+## Per-Task Verification Map
+
+| Task ID | Plan | Wave | Requirement | Threat Ref | Secure Behavior | Test Type | Automated Command | File Exists | Status |
+|---------|------|------|-------------|------------|-----------------|-----------|-------------------|-------------|--------|
+| 8-01-01 | 01 | 1 | API-01 | — | N/A | unit | `vendor/bin/phpunit --filter testHourlyAggregation` | ❌ W0 | ⬜ pending |
+| 8-01-02 | 01 | 1 | API-01 | — | N/A | unit | `vendor/bin/phpunit --filter testDayHourAggregation` | ❌ W0 | ⬜ pending |
+| 8-02-01 | 02 | 1 | FILT-02, FILT-03 | — | N/A | unit | `vendor/bin/phpunit --filter testActivityFilter` | ❌ W0 | ⬜ pending |
+| 8-02-02 | 02 | 1 | FILT-03 | — | N/A | unit | `vendor/bin/phpunit --filter testCustomerFilter` | ❌ W0 | ⬜ pending |
+| 8-03-01 | 03 | 1 | API-02 | — | N/A | unit | `vendor/bin/phpunit --filter testCascadeCustomers` | ❌ W0 | ⬜ pending |
+| 8-03-02 | 03 | 1 | API-02 | — | N/A | unit | `vendor/bin/phpunit --filter testCascadeProjects` | ❌ W0 | ⬜ pending |
+| 8-03-03 | 03 | 1 | API-02 | — | N/A | unit | `vendor/bin/phpunit --filter testCascadeActivities` | ❌ W0 | ⬜ pending |
+
+*Status: ⬜ pending · ✅ green · ❌ red · ⚠️ flaky*
+
+---
+
+## Wave 0 Requirements
+
+- [ ] `Tests/Controller/HeatmapControllerTest.php` — extend with test stubs for hourly, dayhour, filters, cascade endpoints
+- [ ] `Tests/Service/HeatmapServiceTest.php` — stubs for aggregation methods (if unit testing service separately)
+
+*Existing PHPUnit infrastructure covers framework needs.*
+
+---
+
+## Manual-Only Verifications
+
+*All phase behaviors have automated verification.*
+
+---
+
+## Validation Sign-Off
+
+- [ ] All tasks have `<automated>` verify or Wave 0 dependencies
+- [ ] Sampling continuity: no 3 consecutive tasks without automated verify
+- [ ] Wave 0 covers all MISSING references
+- [ ] No watch-mode flags
+- [ ] Feedback latency < 5s
+- [ ] `nyquist_compliant: true` set in frontmatter
+
+**Approval:** pending