diff --git a/.github/workflows/opentofu.yml b/.github/workflows/opentofu.yml
index 098bcca..bcc2f47 100644
--- a/.github/workflows/opentofu.yml
+++ b/.github/workflows/opentofu.yml
@@ -19,5 +19,8 @@ jobs:
       github.event_name != 'pull_request' ||
       github.event.pull_request.head.repo.full_name == github.repository
     uses: makeitworkcloud/shared-workflows/.github/workflows/opentofu.yml@main
+    with:
+      aws-region: us-west-2
+      aws-role-to-assume: arn:aws:iam::332355796717:role/github-actions-twilio-state
     secrets:
       CHART_UPDATER_GITHUB_APP_PRIVATE_KEY: ${{ secrets.CHART_UPDATER_GITHUB_APP_PRIVATE_KEY }}
diff --git a/Makefile b/Makefile
index a8476b8..97e74e3 100644
--- a/Makefile
+++ b/Makefile
@@ -1,23 +1,30 @@
 SHELL     := /bin/bash
 TERRAFORM := $(shell which tofu)
+S3_BUCKET := mitw-tf-twilio-infra
+S3_REGION := us-west-2
+S3_KEY    := tofu/twilio/terraform.tfstate
 
 .PHONY: clean init plan apply test pre-commit-config pre-commit-check-deps pre-commit-install-hooks
 
 clean:
 	@find . -name .terraform -type d | xargs -r rm -rf
 
-# Bootstrap deliberately uses no remote backend until the encrypted backend
-# contract and least-privilege CI access are established in a later PR.
+# tfroot-aws owns this private, versioned state bucket and the GitHub OIDC role
+# that CI assumes. The backend needs no static AWS credentials.
 init: clean
-	@${TERRAFORM} init -backend=false -upgrade -input=false
+	@${TERRAFORM} init -reconfigure -upgrade -input=false \
+		-backend-config="bucket=${S3_BUCKET}" \
+		-backend-config="key=${S3_KEY}" \
+		-backend-config="region=${S3_REGION}" \
+		-backend-config="use_lockfile=true"
 
 plan: init
-	@${TERRAFORM} plan -refresh=false -input=false -lock=false -compact-warnings
+	@${TERRAFORM} plan -refresh=false -input=false -compact-warnings
 
 # There are intentionally no provider configurations or Twilio resources in
-# this bootstrap, so the main-branch apply has no provider-side effect.
+# this root, so backend selection is the only stateful behavior on main.
 apply: init
-	@${TERRAFORM} apply -auto-approve -refresh=false -input=false -lock=false -compact-warnings
+	@${TERRAFORM} apply -auto-approve -refresh=false -input=false -compact-warnings
 
 test: pre-commit-config pre-commit-install-hooks
 	@pre-commit run -a
diff --git a/docs/bootstrap.md b/docs/bootstrap.md
index eaf9785..5e18d1b 100644
--- a/docs/bootstrap.md
+++ b/docs/bootstrap.md
@@ -2,9 +2,9 @@
 
 ## Scope
 
-This initial root validates the OpenTofu toolchain and provider installation only. It creates, imports, updates, or deletes **no** Twilio resources. In particular, it does not purchase or configure phone numbers, webhooks, credentials, messaging services, or runtime routing.
+This root validates the OpenTofu toolchain, remote state backend, and provider installation only. It creates, imports, updates, or deletes **no** Twilio resources. In particular, it does not purchase or configure phone numbers, webhooks, credentials, messaging services, or runtime routing.
 
-The evaluated provider is `RJPearson94/twilio` `0.27.1`. Registry documentation confirms it supports Twilio phone-number resources and inbound `messaging` webhook fields, but it is community-maintained and requires existing account credentials. The bootstrap intentionally declares no provider configuration, so CI receives no Twilio credentials and performs no provider-side API call.
+The evaluated provider is `RJPearson94/twilio` `0.27.1`. Registry documentation confirms it supports Twilio phone-number resources and inbound `messaging` webhook fields, but it is community-maintained and requires existing account credentials. The root intentionally declares no provider configuration, so CI receives no Twilio credentials and performs no provider-side API call.
 
 ## Ownership boundary
 
@@ -12,13 +12,9 @@ The future root may own only Twilio phone-number inventory and inbound messaging
 
 ## Backend and credential contract
 
-The checked-in `.sops.yaml` identifies the approved encryption recipient but no encrypted secret file exists yet. A later, separately reviewed change must:
+[`tfroot-aws` PR #43](https://github.com/makeitworkcloud/tfroot-aws/pull/43) created the canonical backend producer: a dedicated private, encrypted, versioned bucket and an exact-repository GitHub OIDC role restricted to the state object, lockfile, and SOPS KMS decrypt/describe access. This root selects that backend through the reusable workflow's `aws-role-to-assume` input and uses S3 native locking. No static AWS backend credential is stored in source or GitHub Actions secrets.
 
-1. establish least-privilege GitHub Actions OIDC access for this exact repository to decrypt SOPS material;
-2. add an encrypted backend configuration for a dedicated Twilio state object; and
-3. define an existing Twilio credential delivery path that cannot expose a token in source, CI logs, or OpenTofu state.
-
-Only after those prerequisites pass pull-request validation may a later root change add provider configuration or Twilio inventory. Any actual Twilio provisioning or webhook update still requires explicit owner confirmation before merge because `main` invokes the environment-gated apply path.
+The checked-in `.sops.yaml` identifies the approved encryption recipient but no encrypted secret file exists yet. A later, separately reviewed change must define a Twilio credential delivery path that cannot expose a token in source, CI logs, or OpenTofu state. Only after that prerequisite passes pull-request validation may a later root change add provider configuration or Twilio inventory. Any actual Twilio provisioning or webhook update still requires explicit owner confirmation before merge because `main` invokes the environment-gated apply path.
 
 ## Central generated files
 
diff --git a/main.tf b/main.tf
index adbd32e..2f16480 100644
--- a/main.tf
+++ b/main.tf
@@ -1,3 +1,4 @@
-# Bootstrap intentionally contains no Twilio resources, data sources, provider
-# configuration, or secret material. The next root change must first establish
-# the encrypted backend and credential-delivery contract described in docs/bootstrap.md.
+# This root has a selected remote backend but intentionally contains no Twilio
+# resources, data sources, provider configuration, or secret material. A later
+# reviewed change must establish encrypted credential delivery before adding a
+# provider block or managing Twilio inventory.
diff --git a/providers.tf b/providers.tf
index e580aec..1b1e825 100644
--- a/providers.tf
+++ b/providers.tf
@@ -1,6 +1,8 @@
 terraform {
   required_version = "> 1.3"
 
+  backend "s3" {}
+
   required_providers {
     twilio = {
       source  = "RJPearson94/twilio"
@@ -9,10 +11,5 @@ terraform {
   }
 }
 
-# The permanent S3 backend is intentionally omitted until its encrypted
-# contract and least-privilege CI access are reviewed in a follow-up PR.
-# The bootstrap Makefile initializes with -backend=false.
-
-# No provider block is declared during bootstrap. The candidate provider is
-# installed and syntax-validated without receiving credentials or managing
-# Twilio resources.
+# No provider block is declared. The selected backend is independent of Twilio
+# credentials and resource management; those remain separate follow-up gates.