OTP DLT Rollback

When to rollback

• DLT provider rejection at scale
• Incorrect template metadata discovered in production
• OTP delivery success rate below SLO
• Any P1 incident during DLT rollout

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Rollback procedure

Steps

1. Set OTP_DLT_ENABLED=false in deployment environment (or backend/.env).
2. Restart the backend process (required — env read at startup).
3. Verify startup log: otp_dlt_activation_status with "globalEnabled": false.
4. Send test OTP — logs should show deliveryMode: legacy_q and no otp_dlt_dispatch.
5. Confirm provider_response with route: q (NOTIFICATION category).

Time to effect: One process restart.

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Per-app rollback (without global flag)

Set dltEnabled: false in backend/config/otp-mappings.json for the affected app and restart.

Global flag off overrides all apps immediately.

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Re-enable fallback for a DLT-only app (Phase 8D)

Use when a retired app (legacyRouteEnabled: false) experiences DLT failures and you need route=q fallback without disabling DLT globally.

Steps

1. Edit backend/config/otp-mappings.json — set legacyRouteEnabled: true for the affected appId.
2. Restart backend.
3. Verify startup log otp_cutover_status shows app in hybridApps (not retiredApps).
4. Confirm /platform/otp → Delivery policy shows Fallback: enabled, Mode: Hybrid.
5. Trigger test OTP; on simulated DLT failure, logs should show otp_dlt_fallback then providerRoute: q.

Time to effect: One process restart.

Cutover checklist (reverse)

• Root cause of DLT failure understood
• Stakeholder notified of temporary hybrid mode
• otp_dlt_hard_failure rate returns to zero
• Plan to re-retire (legacyRouteEnabled: false) after 30-day stability

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User impact

Scenario	Impact
Rollback before send completes	User sees 502; OTP revoked; can retry
Rollback after successful send	OTP valid; SMS already delivered (DLT or legacy)
Mixed in-flight	Some DLT, some legacy SMS; verify unchanged

API contracts unchanged — clients cannot distinguish delivery mode from responses.

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Verification checklist

• OTP_DLT_ENABLED=false in running environment
• otp_dlt_fallback may appear if global was true with per-app off; after global off, fallback stops
• otp_delivery_completed shows deliveryMode: legacy_q, providerRoute: q
• OTP verify flow unchanged

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Re-enable

Follow Rollout runbook after root cause fixed.