diff --git a/.planning/phases/06-new-backends/06-VALIDATION.md b/.planning/phases/06-new-backends/06-VALIDATION.md
new file mode 100644
index 0000000..18fff78
--- /dev/null
+++ b/.planning/phases/06-new-backends/06-VALIDATION.md
@@ -0,0 +1,80 @@
+---
+phase: 6
+slug: new-backends
+status: draft
+nyquist_compliant: false
+wave_0_complete: false
+created: 2026-03-30
+---
+
+# Phase 6 — Validation Strategy
+
+> Per-phase validation contract for feedback sampling during execution.
+
+---
+
+## Test Infrastructure
+
+| Property | Value |
+|----------|-------|
+| **Framework** | Vitest 4.1.1 |
+| **Config file** | `vitest.config.ts` (root) |
+| **Quick run command** | `npx vitest run src/schemas/registry.test.ts src/generators/rclone-conf.test.ts src/components/wizard/RemoteConfigStep.test.tsx` |
+| **Full suite command** | `npx vitest run` |
+| **Estimated runtime** | ~15 seconds |
+
+---
+
+## Sampling Rate
+
+- **After every task commit:** Run `npx vitest run`
+- **After every plan wave:** Run `npx vitest run` + `npx tsc --noEmit`
+- **Before `/gsd:verify-work`:** Full suite must be green + zero TypeScript errors
+- **Max feedback latency:** ~15 seconds
+
+---
+
+## Per-Task Verification Map
+
+| Task ID | Plan | Wave | Requirement | Test Type | Automated Command | File Exists | Status |
+|---------|------|------|-------------|-----------|-------------------|-------------|--------|
+| 06-W0-01 | W0 | 0 | BACK-01..04 | unit | `npx vitest run src/schemas/registry.test.ts` | ❌ W0 | ⬜ pending |
+| 06-W0-02 | W0 | 0 | BACK-01..04 | unit | `npx vitest run src/generators/rclone-conf.test.ts` | ❌ W0 | ⬜ pending |
+| 06-W0-03 | W0 | 0 | BACK-01..04 | unit | `npx vitest run src/components/wizard/RemoteConfigStep.test.tsx` | ❌ W0 | ⬜ pending |
+| 06-01-01 | 01 | 1 | BACK-01 | unit | `npx vitest run src/schemas/registry.test.ts src/generators/rclone-conf.test.ts` | ❌ W0 | ⬜ pending |
+| 06-01-02 | 01 | 1 | BACK-02 | unit | `npx vitest run src/schemas/registry.test.ts src/generators/rclone-conf.test.ts src/components/wizard/RemoteConfigStep.test.tsx` | ❌ W0 | ⬜ pending |
+| 06-01-03 | 01 | 1 | BACK-03 | unit | `npx vitest run src/schemas/registry.test.ts src/generators/rclone-conf.test.ts` | ❌ W0 | ⬜ pending |
+| 06-01-04 | 01 | 1 | BACK-04 | unit | `npx vitest run src/schemas/registry.test.ts src/generators/rclone-conf.test.ts` | ❌ W0 | ⬜ pending |
+| 06-02-01 | 02 | 2 | BACK-01..04 | unit | `npx vitest run` | ✅ | ⬜ pending |
+
+*Status: ⬜ pending · ✅ green · ❌ red · ⚠️ flaky*
+
+---
+
+## Wave 0 Requirements
+
+- [ ] `src/schemas/registry.test.ts` — update `EXPECTED_BACKENDS` to include all 7 backends; add SFTP assertions (host, user, pass, key_pem); add B2 (account, key); add GCS (project_number, service_account_credentials); add OneDrive (token, drive_id, drive_type)
+- [ ] `src/generators/rclone-conf.test.ts` — add fixtures for onedrive, sftp (password), sftp (key), gcs, b2; assert type string and key fields; assert gcs produces `type = google cloud storage` (with spaces)
+- [ ] `src/components/wizard/RemoteConfigStep.test.tsx` — add describe blocks for BACK-01 (OneDrive), BACK-02 (SFTP with toggle assertions), BACK-03 (GCS), BACK-04 (B2) using existing `renderWithBackend` helper
+
+---
+
+## Manual-Only Verifications
+
+| Behavior | Requirement | Why Manual | Test Instructions |
+|----------|-------------|------------|-------------------|
+| All 4 new backends appear in BackendSelectionStep UI | BACK-01..04 | Visual confirmation of card layout | Open wizard, confirm OneDrive, SFTP, GCS, B2 cards visible |
+| Download bundle contains valid rclone.conf + scripts | BACK-01..04 | File download flow requires browser interaction | Complete wizard for each backend, download bundle, inspect contents |
+
+---
+
+## 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 < 15s
+- [ ] `nyquist_compliant: true` set in frontmatter
+
+**Approval:** pending