docs(phase-15): add research and validation strategy

.planning/phases/15-multi-signer-backend/15-VALIDATION.md

@@ -0,0 +1,80 @@
+---
+phase: 15
+slug: multi-signer-backend
+status: draft
+nyquist_compliant: false
+wave_0_complete: false
+created: 2026-04-03
+---
+
+# Phase 15 — Validation Strategy
+
+> Per-phase validation contract for feedback sampling during execution.
+
+---
+
+## Test Infrastructure
+
+| Property | Value |
+|----------|-------|
+| **Framework** | jest 29.x |
+| **Config file** | `teressa-copeland-homes/jest.config.ts` |
+| **Quick run command** | `npx jest --passWithNoTests --no-coverage` |
+| **Full suite command** | `npx jest --passWithNoTests --no-coverage` |
+| **Estimated runtime** | ~1 second |
+
+---
+
+## Sampling Rate
+
+- **After every task commit:** Run `npx jest --passWithNoTests --no-coverage`
+- **After every plan wave:** Run `npx jest --passWithNoTests --no-coverage`
+- **Before `/gsd:verify-work`:** Full suite must be green
+- **Max feedback latency:** ~3 seconds
+
+---
+
+## Per-Task Verification Map
+
+| Task ID | Plan | Wave | Requirement | Test Type | Automated Command | File Exists | Status |
+|---------|------|------|-------------|-----------|-------------------|-------------|--------|
+| 15-01-01 | 01 | 1 | MSIGN-06 | unit+compile | `npx tsc --noEmit && npx jest` | ✅ existing | ⬜ pending |
+| 15-01-02 | 01 | 1 | MSIGN-05 | compile+audit | `npx tsc --noEmit` | ✅ existing | ⬜ pending |
+| 15-02-01 | 02 | 2 | MSIGN-07 | compile | `npx tsc --noEmit` | ✅ existing | ⬜ pending |
+| 15-02-02 | 02 | 2 | MSIGN-07,MSIGN-10,MSIGN-11 | compile | `npx tsc --noEmit` | ✅ existing | ⬜ pending |
+| 15-03-01 | 03 | 3 | MSIGN-10,MSIGN-11 | compile | `npx tsc --noEmit` | ❌ W0 | ⬜ pending |
+
+*Status: ⬜ pending · ✅ green · ❌ red · ⚠️ flaky*
+
+---
+
+## Wave 0 Requirements
+
+- [ ] `teressa-copeland-homes/src/lib/signing/__tests__/multi-signer.test.ts` — stubs for MSIGN-10, MSIGN-11 (completion detection, signer-download token creation)
+
+*Existing jest infrastructure covers most phase requirements; one test file needed for completion logic.*
+
+---
+
+## Manual-Only Verifications
+
+| Behavior | Requirement | Why Manual | Test Instructions |
+|----------|-------------|------------|-------------------|
+| Two signers both receive emails after send | MSIGN-06 | Requires live email delivery | Send doc with 2 signers, verify both inboxes receive signing links |
+| Each signer's signing page shows only their fields | MSIGN-07 | Browser + real document required | Sign as signer A, confirm only A's fields visible; repeat for B |
+| Final PDF emailed to all parties on completion | MSIGN-10, MSIGN-11 | Requires full signing ceremony | Complete both signers, verify agent + both signers receive completion emails with download links |
+
+*If none: "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