diff --git a/backend/src/auth/auth.ts b/backend/src/auth/auth.ts
index e73008ac..b2633022 100644
--- a/backend/src/auth/auth.ts
+++ b/backend/src/auth/auth.ts
@@ -82,6 +82,12 @@ export function authenticateSession(deps: AuthDependencies): preHandlerHookHandl
     const snapshot = captureAuthConfigSnapshot(request, deps.authentication);
     if (isPublicRoute(request)) return;
 
+    const operator = loopbackMaintenancePrincipal(request);
+    if (operator) {
+      request.principal = operator;
+      return;
+    }
+
     if (legacy) {
       await legacy(request, reply);
       if (reply.sent || !STATE_CHANGING_METHODS.has(request.method)) return;
@@ -138,6 +144,15 @@ export function authenticateSession(deps: AuthDependencies): preHandlerHookHandl
   };
 }
 
+function loopbackMaintenancePrincipal(request: FastifyRequest): PrincipalContext | undefined {
+  if (request.ip !== "127.0.0.1" && request.ip !== "::1" && request.ip !== "::ffff:127.0.0.1") return undefined;
+  if (singleHeader(request.headers["x-thoth-principal-issuer"]) !== "tht"
+    || singleHeader(request.headers["x-thoth-principal-subject"]) !== "tht-maintenance"
+    || singleHeader(request.headers["x-thoth-principal-display-name"]) !== "Tht maintenance"
+    || singleHeader(request.headers["x-thoth-is-admin"]) !== "1") return undefined;
+  return upstreamPrincipal(request.headers);
+}
+
 export function requireCsrf(request: FastifyRequest, reply: FastifyReply): true | FastifyReply {
   const expectedOrigin = request.authPublicOrigin;
   const token = request.authSessionToken;
diff --git a/backend/src/auth/windows-auth-storage.ts b/backend/src/auth/windows-auth-storage.ts
index 4de5f24e..0e03ef8e 100644
--- a/backend/src/auth/windows-auth-storage.ts
+++ b/backend/src/auth/windows-auth-storage.ts
@@ -173,7 +173,7 @@ function validateFilename(filename: string, allowClaim = false, allowOidcSlot =
 }
 
 function safeThtExecutable(value: string | undefined, pathStyle: AuthStoragePathStyle): string {
-  const executable = value ?? process.env.THT_BIN ?? "tht";
+  const executable = value ?? process.env.THT_AUTH_STORAGE_BIN ?? process.env.THT_BIN ?? "tht";
   if (typeof executable !== "string" || executable.length === 0 || /[\u0000-\u001f\u007f]/.test(executable)) throw invalid();
   if (executable === "tht" || (pathStyle === "windows" && executable === "tht.exe")) return executable;
   const paths = pathStyle === "windows" ? win32 : posix;
diff --git a/backend/src/server.ts b/backend/src/server.ts
index df9f3536..06bf5f7f 100644
--- a/backend/src/server.ts
+++ b/backend/src/server.ts
@@ -1,5 +1,6 @@
 import { buildApp, type AppWithAuthSessionStore } from "./app.js";
 import { loadConfig } from "./config.js";
+import { formatStartupFailure } from "./startup-error.js";
 const config = loadConfig(process.env);
 const app = buildApp(config) as AppWithAuthSessionStore;
 
@@ -17,7 +18,7 @@ async function start(): Promise<void> {
   console.log(`backend listening on ${address}`);
 }
 
-void start().catch(() => {
-  console.error("backend startup failed");
+void start().catch((error: unknown) => {
+  console.error(formatStartupFailure(error));
   process.exitCode = 1;
 });
diff --git a/backend/src/startup-error.ts b/backend/src/startup-error.ts
new file mode 100644
index 00000000..d04ea6ce
--- /dev/null
+++ b/backend/src/startup-error.ts
@@ -0,0 +1,12 @@
+const STARTUP_CAUSES = new Set([
+  "auth_config_invalid",
+  "auth_session_store_invalid",
+  "workspace_registry_invalid",
+]);
+
+/** Return one bounded machine cause; never include the original error text or stack. */
+export function formatStartupFailure(error: unknown): string {
+  const message = error instanceof Error ? error.message : "";
+  const cause = STARTUP_CAUSES.has(message) ? message : "startup_unknown";
+  return `backend startup failed: ${cause}`;
+}
diff --git a/backend/test/auth.test.ts b/backend/test/auth.test.ts
index 20044f7d..dcbd1ac1 100644
--- a/backend/test/auth.test.ts
+++ b/backend/test/auth.test.ts
@@ -184,6 +184,43 @@ test("the session boundary exposes only exact health and authentication protocol
   expect((await app.inject({ method: "GET", url: "/auth/configured" })).statusCode).toBe(401);
 });
 
+test("the session boundary retains the exact loopback tht maintenance identity in configured auth modes", async () => {
+  const app = Fastify();
+  app.addHook("preHandler", authenticateSession({ mode: "local" }));
+  app.get("/private", async (request) => getPrincipal(request));
+  app.post("/private", async (request) => getPrincipal(request));
+  const headers = {
+    "x-thoth-principal-issuer": "tht",
+    "x-thoth-principal-subject": "tht-maintenance",
+    "x-thoth-principal-display-name": "Tht maintenance",
+    "x-thoth-is-admin": "1",
+  };
+
+  for (const method of ["GET", "POST"] as const) {
+    const response = await app.inject({ method, url: "/private", headers, remoteAddress: "127.0.0.1" });
+    expect(response.statusCode).toBe(200);
+    expect(response.json()).toMatchObject({ issuer: "tht", subject: "tht-maintenance", isAdmin: true });
+  }
+});
+
+test("the session boundary rejects tht maintenance headers outside exact loopback provenance", async () => {
+  const app = Fastify();
+  app.addHook("preHandler", authenticateSession({ mode: "local" }));
+  app.get("/private", async (request) => getPrincipal(request));
+  const exact = {
+    "x-thoth-principal-issuer": "tht",
+    "x-thoth-principal-subject": "tht-maintenance",
+    "x-thoth-principal-display-name": "Tht maintenance",
+    "x-thoth-is-admin": "1",
+  };
+
+  expect((await app.inject({ method: "GET", url: "/private", headers: exact, remoteAddress: "172.30.0.9" })).statusCode).toBe(503);
+  expect((await app.inject({
+    method: "GET", url: "/private", remoteAddress: "127.0.0.1",
+    headers: { ...exact, "x-thoth-principal-subject": "not-maintenance" },
+  })).statusCode).toBe(503);
+});
+
 test("the session boundary touches a valid cookie session through the bounded Task 7 store operation", async () => {
   const sessions = {
     resolve: vi.fn(async () => ({
diff --git a/backend/test/startup-error.test.ts b/backend/test/startup-error.test.ts
new file mode 100644
index 00000000..bf1685bd
--- /dev/null
+++ b/backend/test/startup-error.test.ts
@@ -0,0 +1,28 @@
+import { describe, expect, it } from "vitest";
+import { formatStartupFailure } from "../src/startup-error.js";
+
+describe("formatStartupFailure", () => {
+  it.each([
+    [new Error("auth_session_store_invalid"), "backend startup failed: auth_session_store_invalid"],
+    [new Error("auth_config_invalid"), "backend startup failed: auth_config_invalid"],
+    [new Error("workspace_registry_invalid"), "backend startup failed: workspace_registry_invalid"],
+  ])("emits only an allowlisted startup cause", (error, expected) => {
+    expect(formatStartupFailure(error)).toBe(expected);
+  });
+
+  it("collapses unknown errors without exposing their message, stack, token, or path", () => {
+    const error = new Error(
+      "EACCES password=plain-secret token=token-secret at /run/secrets/private-token",
+    );
+    error.stack = "Error: raw failure\n    at /app/backend/dist/server.js:42:1";
+
+    const formatted = formatStartupFailure(error);
+
+    expect(formatted).toBe("backend startup failed: startup_unknown");
+    for (const leaked of [
+      "EACCES", "plain-secret", "token-secret", "/run/secrets", "raw failure", "server.js",
+    ]) {
+      expect(formatted).not.toContain(leaked);
+    }
+  });
+});
diff --git a/backend/test/windows-auth-storage.test.ts b/backend/test/windows-auth-storage.test.ts
index fcd4546e..ac8fed9a 100644
--- a/backend/test/windows-auth-storage.test.ts
+++ b/backend/test/windows-auth-storage.test.ts
@@ -93,6 +93,29 @@ function bridgeForChild(child: FakeBridgeChild, pathStyle: "windows" | "posix" =
 }
 
 describe("Windows auth-storage bridge", () => {
+  test("uses a dedicated native storage executable without replacing the harness tht", async () => {
+    vi.stubEnv("THT_BIN", "/opt/venv/bin/tht");
+    vi.stubEnv("THT_AUTH_STORAGE_BIN", "/usr/local/bin/tht-auth-storage");
+    const calls: Array<{ executable: string }> = [];
+    const bridge = createPosixAuthStorageBridge({
+      invoke: async (call) => {
+        calls.push(call);
+        return {
+          code: 0,
+          stdout: Buffer.from('{"version":1,"ok":true,"prepared":true}\n'),
+          stderr: Buffer.alloc(0),
+        };
+      },
+    });
+
+    await bridge.ensureLayout("/data/auth");
+
+    expect(calls).toHaveLength(1);
+    expect(calls[0]!.executable).toBe("/usr/local/bin/tht-auth-storage");
+    expect(process.env.THT_BIN).toBe("/opt/venv/bin/tht");
+    vi.unstubAllEnvs();
+  });
+
   test("uses the same bounded hidden bridge to ensure a POSIX session layout", async () => {
     const calls: Array<{ executable: string; args: readonly string[]; input: Buffer; timeoutMs: number }> = [];
     const bridge = createPosixAuthStorageBridge({
diff --git a/docker/core-entrypoint.sh b/docker/core-entrypoint.sh
index 6f9049cc..df2280e1 100755
--- a/docker/core-entrypoint.sh
+++ b/docker/core-entrypoint.sh
@@ -13,6 +13,10 @@ node /app/docker/ensure-pi-trust.mjs "${THT_HARNESS_DIR:-/app/harness}"
 cmd="${1:-server}"
 case "$cmd" in
   server)
+    [[ "${THT_AUTH_STATE_ROOT:-/data/auth}" == /data/auth ]] \
+      || { printf '%s\n' 'authentication state root is invalid' >&2; exit 1; }
+    printf '%s\n' '{"version":1,"operation":"ensure-layout","root":"/data/auth"}' \
+      | "${THT_AUTH_STORAGE_BIN:-/usr/local/bin/tht-auth-storage}" _auth-storage >/dev/null
     exec node /app/backend/dist/server.js
     ;;
   check)
diff --git a/docker/core.Dockerfile b/docker/core.Dockerfile
index 0d37203c..410eeff4 100644
--- a/docker/core.Dockerfile
+++ b/docker/core.Dockerfile
@@ -7,6 +7,14 @@ ARG IMAGE_VERSION=local
 # ---- Pinned Node source for the runtime binary and npm ----
 FROM node:24.16.0-bookworm@sha256:40ad9f3064e67d6860b4bc3fe1880b2953934fd6320ada990e45fe0efa6badd7 AS node-runtime
 
+# ---- Pinned native storage helper used by the authenticated backend ----
+FROM golang:1.26.5-bookworm@sha256:1ecb7edf62a0408027bd5729dfd6b1b8766e578e8df93995b225dfd0944eb651 AS tht-auth-storage-build
+WORKDIR /src/tools/tht
+COPY tools/tht/go.mod tools/tht/go.sum ./
+RUN go mod download
+COPY tools/tht ./
+RUN CGO_ENABLED=0 go build -trimpath -ldflags='-s -w' -o /out/tht-auth-storage ./cmd/tht
+
 # ---- Stage 0: locked Pi runtime ----
 FROM node:24.16.0-bookworm@sha256:40ad9f3064e67d6860b4bc3fe1880b2953934fd6320ada990e45fe0efa6badd7 AS pi-runtime-build
 ARG PI_VERSION
@@ -61,7 +69,9 @@ RUN useradd --create-home --uid 10001 --shell /bin/bash thoth
 # Docker copies these owned directories into newly-created named volumes, allowing the non-root
 # runtime user to create application settings, sessions, registry snapshots, state, and locks.
 RUN mkdir -p /home/thoth/.pi/agent /data/settings /data/sessions /data/workspace-registry /data/workspace-secrets \
- && chown -R thoth:thoth /home/thoth/.pi /data
+      /data/auth/sessions /data/auth/oidc \
+ && chown -R thoth:thoth /home/thoth/.pi /data \
+ && chmod 0700 /data/auth /data/auth/sessions /data/auth/oidc
 
 COPY harness/ /app/harness/
 # Pi scrive lock/settings in .pi: ownership thoth per sopravvivere al rebuild
@@ -91,14 +101,17 @@ COPY backend/package*.json /app/backend/
 # Runtime Pi is installed only from the committed lockfile. The image exposes its immutable
 # executable directly, so no host Pi installation or writable global npm directory is needed.
 COPY --from=pi-runtime-build /opt/pi-runtime/node_modules /opt/pi-runtime/node_modules
+COPY --from=tht-auth-storage-build /out/tht-auth-storage /usr/local/bin/tht-auth-storage
 RUN ln -s /opt/pi-runtime/node_modules/.bin/pi /usr/local/bin/pi \
- && test "$(pi --version)" = "$PI_VERSION"
+ && test "$(pi --version)" = "$PI_VERSION" \
+ && test -x /usr/local/bin/tht-auth-storage
 
 ENV PATH="/opt/venv/bin:/usr/local/bin:$PATH" \
     PI_VERSION="${PI_VERSION}" \
     HOST=0.0.0.0 PORT=8787 \
     THT_HARNESS_DIR=/app/harness \
     THT_BIN=/opt/venv/bin/tht \
+    THT_AUTH_STORAGE_BIN=/usr/local/bin/tht-auth-storage \
     PI_BIN=pi \
     HOME=/home/thoth
 
diff --git a/scripts/test-default-compose.sh b/scripts/test-default-compose.sh
index 4b968dfd..05207a90 100755
--- a/scripts/test-default-compose.sh
+++ b/scripts/test-default-compose.sh
@@ -24,8 +24,19 @@ if (services.join(",") !== "core,embedding,embedding-model-init,frontend,qdrant"
 if (/omics_portal|chirone|localllm_default|\/home\/chirone/i.test(JSON.stringify(config))) {
   throw new Error("default Compose contains application-specific coupling");
 }
-for (const volume of ["settings", "pi-state", "workspace-registry", "sessions", "auth-state", "qdrant-data", "embedding-models"]) {
-  if (!config.volumes || !config.volumes[volume]) throw new Error(`missing required volume: ${volume}`);
+const expectedVolumes = [
+  "auth-state",
+  "embedding-models",
+  "pi-state",
+  "qdrant-data",
+  "sessions",
+  "settings",
+  "workspace-registry",
+  "workspace-secrets",
+];
+const actualVolumes = Object.keys(config.volumes || {});
+if (actualVolumes.join(",") !== expectedVolumes.join(",")) {
+  throw new Error(`unexpected ordered volume set: ${actualVolumes.join(",")}`);
 }
 const core = config.services.core;
 const frontend = config.services.frontend;
diff --git a/scripts/unified-deployment-smoke.sh b/scripts/unified-deployment-smoke.sh
index a8a6d669..636d40b2 100755
--- a/scripts/unified-deployment-smoke.sh
+++ b/scripts/unified-deployment-smoke.sh
@@ -166,6 +166,44 @@ task13_compose_logged() {
   task13_run_logged "$label" "${TASK13_COMPOSE[@]}" "$@"
 }
 
+task13_report_core_startup_failure() {
+  local container_id state exit_code logs cause="startup failure is unclassified"
+  container_id="$(task13_compose ps --all -q core 2>/dev/null | head -n 1 || true)"
+  state=""
+  if [[ -n "$container_id" ]]; then
+    state="$(docker inspect --format '{{.State.Status}}:{{.State.ExitCode}}' "$container_id" 2>/dev/null || true)"
+  fi
+  exit_code="${state##*:}"
+  [[ "$exit_code" =~ ^[0-9]{1,3}$ ]] || exit_code="unknown"
+  logs="$(task13_compose logs --no-color --tail 100 core 2>/dev/null || true)"
+  case "$logs" in
+    *auth_session_store_invalid*|*auth*storage*request*failed*|*EACCES*auth*|*permission*auth*)
+      cause="authentication state storage is unavailable"
+      ;;
+    *auth_config_invalid*|*authentication*configuration*)
+      cause="authentication configuration is invalid"
+      ;;
+    *workspace_registry_invalid*|*workspace*registry*)
+      cause="workspace registry startup validation failed"
+      ;;
+  esac
+  printf 'Core startup cause: %s (exit code %s).\n' "$cause" "$exit_code" >&2
+}
+
+task13_compose_start_logged() {
+  local label="$1"
+  shift
+  task13_compose_files
+  if task13_bounded "$TASK13_COMMAND_TIMEOUT" "$label" \
+    "${TASK13_COMPOSE[@]}" "$@" >>"$TASK13_LOG" 2>&1; then
+    return 0
+  fi
+  TASK13_FAILURE_LOGGED=1
+  printf 'Task 13 command failed: %s\n' "$label" >&2
+  task13_report_core_startup_failure
+  return 1
+}
+
 task13_write_environment() {
   local remote="$1"
   {
@@ -296,6 +334,7 @@ services:
       - $TASK13_PI_MODELS:/home/thoth/.pi/agent/models.json:ro
       - $TASK13_PI_SETTINGS:/home/thoth/.pi/agent/settings.json:ro
       - workspace-registry:/data/workspace-registry
+      - workspace-secrets:/data/workspace-secrets
       - sessions:/data/sessions
       - $TASK13_AUTH_ROOT:/run/thothii-auth:ro
       - auth-state:/data/auth
@@ -333,6 +372,9 @@ volumes:
   workspace-registry:
     labels:
       io.thothii.task13.run: "$TASK13_RUN_ID"
+  workspace-secrets:
+    labels:
+      io.thothii.task13.run: "$TASK13_RUN_ID"
   sessions:
     labels:
       io.thothii.task13.run: "$TASK13_RUN_ID"
@@ -362,6 +404,9 @@ EOF
 
 task13_write_server_fixture_files() {
   local data_root pi_root registry_root remote_path workspace_path
+  TASK13_OIDC_SERVER="${TASK13_OIDC_SERVER:-$TASK13_TMP/fake-oidc.mjs}"
+  TASK13_OIDC_CERT="${TASK13_OIDC_CERT:-$TASK13_TMP/fake-oidc-cert.pem}"
+  TASK13_OIDC_KEY="${TASK13_OIDC_KEY:-$TASK13_TMP/fake-oidc-key.pem}"
   printf '{}\n' >"$TASK13_PI_AUTH"
   printf 'THT_MODEL_API_KEY=%s\nTHT_OIDC_CLIENT_SECRET=%s\nTHT_AUTHENTIK_API_TOKEN=%s\n' \
     "$TASK13_SECRET_VALUE" "$TASK13_OIDC_CLIENT_SECRET" "$TASK13_AUTHENTIK_API_TOKEN" >"$TASK13_SECRETS"
@@ -376,6 +421,63 @@ EOF
   chmod 0600 "$TASK13_SECRETS" "$TASK13_SESSION_RUNTIME_PASSWORD" \
     "$TASK13_SESSION_MIGRATOR_PASSWORD_FILE"
 
+  task13_run_logged "create scoped fake OIDC certificate" openssl req -x509 -newkey rsa:2048 \
+    -sha256 -nodes -days 1 -subj '/CN=task13-fake-oidc' \
+    -addext 'subjectAltName=DNS:task13-fake-oidc' \
+    -keyout "$TASK13_OIDC_KEY" -out "$TASK13_OIDC_CERT"
+  chmod 0600 "$TASK13_OIDC_KEY"
+  chmod 0644 "$TASK13_OIDC_CERT"
+  cat >"$TASK13_OIDC_SERVER" <<'EOF'
+import { createPublicKey, generateKeyPairSync } from "node:crypto";
+import { readFileSync } from "node:fs";
+import https from "node:https";
+
+const origin = "https://task13-fake-oidc:9443";
+const issuer = `${origin}/application/o/task13/`;
+const expectedToken = process.env.TASK13_AUTHENTIK_API_TOKEN;
+const { publicKey } = generateKeyPairSync("rsa", { modulusLength: 2048 });
+const jwk = { ...createPublicKey(publicKey).export({ format: "jwk" }), kid: "task13", use: "sig", alg: "RS256" };
+const send = (response, status, body) => {
+  const payload = JSON.stringify(body);
+  response.writeHead(status, { "content-type": "application/json", "content-length": Buffer.byteLength(payload) });
+  response.end(payload);
+};
+
+const server = https.createServer({
+  cert: readFileSync("/fixtures/oidc-cert.pem"),
+  key: readFileSync("/fixtures/oidc-key.pem"),
+}, (request, response) => {
+  const target = new URL(request.url ?? "/", origin);
+  if (target.pathname === "/health") return send(response, 200, { status: "ok" });
+  if (target.pathname.includes(".well-known/openid-configuration")) {
+    return send(response, 200, {
+      issuer,
+      authorization_endpoint: `${origin}/authorize`,
+      token_endpoint: `${origin}/token`,
+      jwks_uri: `${origin}/jwks`,
+      response_types_supported: ["code"],
+      subject_types_supported: ["public"],
+      id_token_signing_alg_values_supported: ["RS256"],
+    });
+  }
+  if (target.pathname === "/jwks") return send(response, 200, { keys: [jwk] });
+  if (target.pathname === "/api/v3/core/groups/") {
+    if (request.headers.authorization !== `Bearer ${expectedToken}`) return send(response, 401, { detail: "unauthorized" });
+    const name = target.searchParams.get("name") ?? "";
+    console.log(`group:${name}`);
+    const configured = name === "task13-users" || name === "task13-admins";
+    return send(response, 200, {
+      pagination: { next: null },
+      results: configured ? [{ name }, { name: "task13-unrelated" }] : [{ name: "task13-unrelated" }],
+    });
+  }
+  return send(response, 404, { error: "not_found" });
+});
+
+server.listen(9443, "0.0.0.0");
+EOF
+  chmod 0644 "$TASK13_OIDC_SERVER"
+
   cat >"$TASK13_SERVER_WORKSPACE_CONFIG" <<'EOF'
 language: en
 session_storage:
@@ -417,6 +519,7 @@ services:
       labels:
         io.thothii.task13.run: "$TASK13_RUN_ID"
     environment:
+      NODE_EXTRA_CA_CERTS: /fixtures/task13-oidc-ca.pem
       THT_WS_TASK13_SMOKE_DWH_TRANSPORT: postgres_direct
       THT_WS_TASK13_SMOKE_DWH_HOST: dwh.task13.invalid
       THT_WS_TASK13_SMOKE_DWH_PORT: "5432"
@@ -427,6 +530,7 @@ services:
     volumes:
       - $remote_path:/fixtures/remote.git:ro
       - $TASK13_SESSION_RUNTIME_PASSWORD:/run/secrets/task13-runtime-password:ro
+      - $TASK13_OIDC_CERT:/fixtures/task13-oidc-ca.pem:ro
   frontend:
     image: $TASK13_FRONTEND_IMAGE
     build:
@@ -639,15 +743,15 @@ task13_configure_local_authentication() {
 task13_configure_server_oidc_authentication() {
   task13_run_logged "configure fake server OIDC authentication" "$TASK13_THT" --installation "$TASK13_INSTALLATION" auth configure \
     --mode oidc --public-url "https://task13.example.invalid" \
-    --issuer "https://task13-fake-oidc.invalid/application/o/task13/" --client-id task13-smoke-client \
-    --authentik-base-url "https://task13-fake-authentik.invalid" --user-group task13-users --admin-group task13-admins
+    --issuer "https://task13-fake-oidc:9443/application/o/task13/" --client-id task13-smoke-client \
+    --authentik-base-url "https://task13-fake-oidc:9443" --user-group task13-users --admin-group task13-admins
 }
 
 task13_start_stack() {
   printf '== Build and start isolated local Compose distribution ==\n'
   task13_assert_rendered_contract
   task13_compose_logged "build local Compose images" build --pull
-  task13_compose_logged "start local Compose distribution" up --detach --wait --wait-timeout 120
+  task13_compose_start_logged "start local Compose distribution" up --detach --wait --wait-timeout 120
   TASK13_NETWORK="$(docker network ls \
     --filter "label=com.docker.compose.project=$TASK13_PROJECT" \
     --filter 'label=com.docker.compose.network=thothii' --format '{{.Name}}')"
@@ -674,7 +778,36 @@ task13_start_server_stack() {
   printf '== Build and start isolated Linux server profile ==\n'
   task13_assert_rendered_contract
   task13_compose_logged "build server Compose images" build --pull core frontend
-  task13_compose_logged "start server Compose distribution" \
+  task13_compose_logged "create server Compose resources" create core frontend
+  TASK13_NETWORK="$(docker network ls \
+    --filter "label=com.docker.compose.project=$TASK13_PROJECT" \
+    --filter 'label=com.docker.compose.network=thothii' --format '{{.Name}}')"
+  [[ -n "$TASK13_NETWORK" && "$TASK13_NETWORK" != *$'\n'* ]] \
+    || task13_fail "isolated server Compose network was not resolved"
+  task13_run_logged "start scoped fake OIDC provider" docker run --detach \
+    --name "$TASK13_OIDC_CONTAINER" \
+    --label "io.thothii.task13.run=$TASK13_RUN_ID" \
+    --network "$TASK13_NETWORK" --network-alias task13-fake-oidc \
+    --user "$(id -u):$(id -g)" \
+    --env "TASK13_AUTHENTIK_API_TOKEN=$TASK13_AUTHENTIK_API_TOKEN" \
+    --env NODE_EXTRA_CA_CERTS=/fixtures/oidc-cert.pem \
+    --entrypoint node \
+    --volume "$TASK13_OIDC_SERVER:/fixtures/fake-oidc.mjs:ro" \
+    --volume "$TASK13_OIDC_CERT:/fixtures/oidc-cert.pem:ro" \
+    --volume "$TASK13_OIDC_KEY:/fixtures/oidc-key.pem:ro" \
+    "$TASK13_CORE_IMAGE" /fixtures/fake-oidc.mjs
+  for _attempt in $(seq 1 30); do
+    if docker exec "$TASK13_OIDC_CONTAINER" node -e \
+      "fetch('https://task13-fake-oidc:9443/health',{signal:AbortSignal.timeout(3000)}).then(r=>{if(!r.ok)process.exit(1)}).catch(()=>process.exit(1))" \
+      >>"$TASK13_LOG" 2>&1; then
+      break
+    fi
+    sleep 1
+  done
+  docker exec "$TASK13_OIDC_CONTAINER" node -e \
+    "fetch('https://task13-fake-oidc:9443/health',{signal:AbortSignal.timeout(3000)}).then(r=>{if(!r.ok)process.exit(1)}).catch(()=>process.exit(1))" \
+    >>"$TASK13_LOG" 2>&1 || task13_log_failure "scoped fake OIDC provider readiness"
+  task13_compose_start_logged "start server Compose distribution" \
     up --detach --wait --wait-timeout 120 core frontend
 }
 
@@ -729,6 +862,116 @@ task13_assert_local_auth_lifecycle() {
   [[ "$unauthenticated" == 401 ]] || task13_fail "local logout did not revoke the remembered session"
 }
 
+task13_create_admin_session() {
+  local frontend login_body me
+  frontend="$(task13_frontend_address)"
+  TASK13_ADMIN_COOKIE="$TASK13_TMP/operations-admin.cookies"
+  login_body="$TASK13_TMP/operations-admin-login.json"
+  printf '{"username":"%s","password":"%s","remember":true}' \
+    "$TASK13_AUTH_ADMIN" "$TASK13_AUTH_PASSWORD" >"$login_body"
+  chmod 0600 "$login_body"
+  task13_run_logged "create authenticated smoke administration session" curl \
+    --connect-timeout "$TASK13_CURL_CONNECT_TIMEOUT" --max-time "$TASK13_CURL_MAX_TIME" \
+    --fail --silent --show-error --cookie-jar "$TASK13_ADMIN_COOKIE" \
+    -H "Origin: http://$frontend" -H 'content-type: application/json' --data-binary "@$login_body" \
+    "http://$frontend/api/auth/local/login"
+  me="$(curl --connect-timeout "$TASK13_CURL_CONNECT_TIMEOUT" --max-time "$TASK13_CURL_MAX_TIME" \
+    --fail --silent --show-error --cookie "$TASK13_ADMIN_COOKIE" "http://$frontend/api/me")"
+  TASK13_ADMIN_CSRF="$(node -e 'const value=JSON.parse(process.argv[1]); if(typeof value.csrfToken!=="string") process.exit(1); process.stdout.write(value.csrfToken)' "$me")" \
+    || task13_fail "authenticated smoke administration session lacks CSRF state"
+}
+
+task13_authenticated_get() {
+  local path="$1" frontend
+  frontend="$(task13_frontend_address)"
+  curl --connect-timeout "$TASK13_CURL_CONNECT_TIMEOUT" --max-time "$TASK13_CURL_MAX_TIME" \
+    --fail --silent --show-error --cookie "$TASK13_ADMIN_COOKIE" "http://$frontend/api/$path"
+}
+
+task13_authenticated_post() {
+  local path="$1" frontend
+  frontend="$(task13_frontend_address)"
+  curl --connect-timeout "$TASK13_CURL_CONNECT_TIMEOUT" --max-time 15 \
+    --fail --silent --show-error --cookie "$TASK13_ADMIN_COOKIE" \
+    -H "Origin: http://$frontend" -H "x-thothii-csrf: $TASK13_ADMIN_CSRF" \
+    -X POST "http://$frontend/api/$path"
+}
+
+task13_assert_local_restore_reauthentication() {
+  local frontend archive login_body cookie_before cookie_after me status_before status_after
+  frontend="$(task13_frontend_address)"
+  archive="$TASK13_TMP/local-restore-source.zip"
+  login_body="$TASK13_TMP/local-restore-login.json"
+  cookie_before="$TASK13_TMP/local-restore-before.cookies"
+  cookie_after="$TASK13_TMP/local-restore-after.cookies"
+  printf '{"username":"%s","password":"%s","remember":true}' \
+    "$TASK13_AUTH_ADMIN" "$TASK13_AUTH_PASSWORD" >"$login_body"
+  chmod 0600 "$login_body"
+
+  task13_run_logged "create pre-backup browser session" curl \
+    --connect-timeout "$TASK13_CURL_CONNECT_TIMEOUT" --max-time "$TASK13_CURL_MAX_TIME" \
+    --fail --silent --show-error --cookie-jar "$cookie_before" \
+    -H "Origin: http://$frontend" -H 'content-type: application/json' --data-binary "@$login_body" \
+    "http://$frontend/api/auth/local/login"
+  task13_compose_logged "stop local stack for backup" stop
+  task13_run_logged "create real default-custody backup" "$TASK13_THT" \
+    --installation "$TASK13_INSTALLATION" backup --output "$archive"
+  python3 - "$archive" <<'PY'
+import json
+import sys
+import zipfile
+
+with zipfile.ZipFile(sys.argv[1]) as archive:
+    manifest = json.loads(archive.read("manifest.json"))
+volumes = [item["logical_name"] for item in manifest["volumes"]]
+if volumes != ["embedding-models", "pi-state", "qdrant-data", "sessions", "settings", "workspace-registry", "workspace-secrets"]:
+    raise SystemExit(f"unexpected backup volume custody: {volumes}")
+entries = manifest["entries"]
+if any(item.get("logical_name") == "auth-state" or "/data/auth" in item.get("source_path", "") for item in entries):
+    raise SystemExit("default backup contains authentication runtime state")
+auth = [item for item in entries if item["path"].startswith("authentication-secrets/")]
+if len(auth) != 1 or not auth[0]["path"].endswith("-auth.yaml") or auth[0]["archived"]:
+    raise SystemExit("default backup auth custody is not an auth.yaml reference only")
+if any(item["path"].endswith("users.yaml") for item in entries):
+    raise SystemExit("default backup contains users.yaml")
+PY
+
+  task13_compose_start_logged "restart local stack before restore" up --detach --wait --wait-timeout 120
+  status_before="$(curl --connect-timeout "$TASK13_CURL_CONNECT_TIMEOUT" --max-time "$TASK13_CURL_MAX_TIME" \
+    --silent --output /dev/null --write-out '%{http_code}' --cookie "$cookie_before" "http://$frontend/api/me")"
+  [[ "$status_before" == 200 ]] || task13_fail "pre-backup browser session did not survive an ordinary stop/start"
+  task13_run_logged "create post-backup browser session" curl \
+    --connect-timeout "$TASK13_CURL_CONNECT_TIMEOUT" --max-time "$TASK13_CURL_MAX_TIME" \
+    --fail --silent --show-error --cookie-jar "$cookie_after" \
+    -H "Origin: http://$frontend" -H 'content-type: application/json' --data-binary "@$login_body" \
+    "http://$frontend/api/auth/local/login"
+  me="$(curl --connect-timeout "$TASK13_CURL_CONNECT_TIMEOUT" --max-time "$TASK13_CURL_MAX_TIME" \
+    --fail --silent --show-error --cookie "$cookie_after" "http://$frontend/api/me")"
+  node -e 'const value=JSON.parse(process.argv[1]); if(value.issuer!=="local"||value.session?.remembered!==true) process.exit(1)' "$me" \
+    || task13_fail "post-backup browser session was not authenticated"
+  task13_compose_logged "seed pending OIDC state excluded from restore" exec -T core sh -ceu \
+    'printf %s "{}" > /data/auth/oidc/aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa.json && chmod 0600 /data/auth/oidc/aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa.json && test "$(find /data/auth/sessions -type f | wc -l | tr -d " ")" -ge 2'
+
+  task13_compose_logged "stop local stack for restore" stop
+  task13_run_logged "perform real production restore" "$TASK13_THT" \
+    --installation "$TASK13_INSTALLATION" restore "$archive" --yes
+  task13_compose_start_logged "start restored local stack" up --detach --wait --wait-timeout 120
+  status_before="$(curl --connect-timeout "$TASK13_CURL_CONNECT_TIMEOUT" --max-time "$TASK13_CURL_MAX_TIME" \
+    --silent --output /dev/null --write-out '%{http_code}' --cookie "$cookie_before" "http://$frontend/api/me")"
+  status_after="$(curl --connect-timeout "$TASK13_CURL_CONNECT_TIMEOUT" --max-time "$TASK13_CURL_MAX_TIME" \
+    --silent --output /dev/null --write-out '%{http_code}' --cookie "$cookie_after" "http://$frontend/api/me")"
+  [[ "$status_before" == 401 && "$status_after" == 401 ]] \
+    || task13_fail "restore did not force every independent browser session to reauthenticate"
+  task13_compose_logged "verify private empty restored auth state" exec -T core sh -ceu '
+    test "$(stat -c %a /data/auth)" = 700
+    test "$(stat -c %a /data/auth/sessions)" = 700
+    test "$(stat -c %a /data/auth/oidc)" = 700
+    test "$(stat -c %u /data/auth)" = "$(id -u)"
+    test -z "$(find /data/auth/sessions /data/auth/oidc -mindepth 1 -print -quit)"
+  '
+  task13_create_admin_session
+}
+
 task13_assert_runtime() {
   local frontend expected_pi actual_pi core_id
   frontend="$(task13_frontend_address)"
@@ -745,8 +988,10 @@ task13_assert_runtime() {
     'command -v pi >/dev/null'
   task13_compose_logged "core Docker socket isolation" exec -T core sh -ceu \
     'test ! -e /var/run/docker.sock'
-  task13_compose_logged "workspace registry bootstrap" exec -T core \
-    curl --connect-timeout 3 --max-time 10 -fsS http://127.0.0.1:8787/workspace-registry/status
+  task13_assert_local_auth_lifecycle
+  task13_create_admin_session
+  task13_authenticated_get workspace-registry/status >/dev/null \
+    || task13_fail "authenticated workspace registry bootstrap failed"
   task13_compose_logged "active workspace registry state" exec -T core sh -ceu \
     'test -f /data/workspace-registry/state/active.json'
   task13_compose_logged "mounted Pi auth readability" exec -T core sh -ceu \
@@ -757,7 +1002,6 @@ task13_assert_runtime() {
   [[ "$(docker inspect --format '{{ index .Config.Labels "io.thothii.task13.run" }}' "$core_id")" == "$TASK13_RUN_ID" ]] \
     || task13_fail "core lacks the explicit Task 13 resource label"
   task13_assert_maintenance_auth_isolation
-  task13_assert_local_auth_lifecycle
   task13_run_logged "tht Pi doctor" "$TASK13_THT" --installation "$TASK13_INSTALLATION" pi doctor
 }
 
@@ -799,7 +1043,7 @@ task13_report_server_workspace_failure() {
 }
 
 task13_assert_server_runtime() {
-  local frontend unauthenticated trusted_header_status session_status diagnostics diagnostic_status core_id frontend_id
+  local frontend unauthenticated trusted_header_status session_status diagnostics status provider_requests core_id frontend_id
   local expected_core_image expected_frontend_image
   frontend="$(task13_frontend_address)"
   task13_run_logged "server frontend health" curl \
@@ -857,22 +1101,32 @@ task13_assert_server_runtime() {
   if grep -Fq "$TASK13_SECRET_VALUE" "$TASK13_TMP/server-sessions.out"; then
     task13_fail "server session failure exposed the fixture secret"
   fi
+  status="$TASK13_TMP/server-auth-status.json"
+  task13_run_logged "server static OIDC status" "$TASK13_THT" --installation "$TASK13_INSTALLATION" auth status --json
+  "$TASK13_THT" --installation "$TASK13_INSTALLATION" auth status --json >"$status"
+  node -e 'const value=JSON.parse(require("fs").readFileSync(process.argv[1], "utf8")); if(value.mode!=="oidc"||typeof value.configRevision!=="string"||value.configRevision.length!==64) process.exit(1)' "$status" \
+    || task13_fail "server static OIDC status was not valid"
   diagnostics="$TASK13_TMP/server-auth-diagnostics.json"
-  set +e
-  "$TASK13_THT" --installation "$TASK13_INSTALLATION" auth check --json >"$diagnostics" 2>>"$TASK13_LOG"
-  diagnostic_status=$?
-  set -e
-  [[ "$diagnostic_status" == 1 ]] || task13_fail "fake OIDC diagnostics did not fail closed"
-  node -e 'const value=JSON.parse(require("fs").readFileSync(process.argv[1], "utf8")); if(value.mode!=="oidc"||value.ready!==false||!value.checks.some((item)=>item.code==="oidc_discovery_unreachable")) process.exit(1)' "$diagnostics" \
-    || task13_fail "fake OIDC fixture did not produce the expected static diagnostic"
+  task13_run_logged "server live OIDC diagnostics" "$TASK13_THT" --installation "$TASK13_INSTALLATION" auth check --json
+  "$TASK13_THT" --installation "$TASK13_INSTALLATION" auth check --json >"$diagnostics"
+  node -e 'const value=JSON.parse(require("fs").readFileSync(process.argv[1], "utf8")); if(value.mode!=="oidc"||value.ready!==true||value.checks.length!==1||value.checks[0].code!=="auth_ready") process.exit(1)' "$diagnostics" \
+    || task13_fail "scoped fake OIDC provider did not pass live production diagnostics"
+  provider_requests="$(docker logs "$TASK13_OIDC_CONTAINER" 2>>"$TASK13_LOG")"
+  [[ "$(grep -Fc 'group:task13-users' <<<"$provider_requests")" -ge 1 ]] \
+    || task13_fail "live OIDC diagnostics did not verify the mandatory user group"
+  [[ "$(grep -Fc 'group:task13-admins' <<<"$provider_requests")" -ge 1 ]] \
+    || task13_fail "live OIDC diagnostics did not verify the mandatory administrator group"
+  if grep -Fq 'group:task13-unrelated' <<<"$provider_requests" \
+    || grep -Fq 'task13-unrelated' "$diagnostics"; then
+    task13_fail "live OIDC diagnostics queried or warned about an unrelated group"
+  fi
   if grep -Fq "$TASK13_OIDC_CLIENT_SECRET" "$diagnostics" || grep -Fq "$TASK13_AUTHENTIK_API_TOKEN" "$diagnostics"; then
     task13_fail "OIDC diagnostics exposed a fixture secret"
   fi
 }
 
 task13_registry_status() {
-  task13_compose exec -T core curl --connect-timeout 3 --max-time 10 -fsS \
-    http://127.0.0.1:8787/workspace-registry/status
+  task13_authenticated_get workspace-registry/status
 }
 
 task13_registry_head() {
@@ -914,8 +1168,7 @@ task13_prepare_persistence() {
   TASK13_INITIAL_MOUNTS="$(task13_mount_fingerprint)"
   TASK13_INITIAL_HEAD="$(task13_active_registry_head)"
   [[ "$TASK13_INITIAL_HEAD" =~ ^[0-9a-f]{40}$ ]] || task13_fail "initial registry head is invalid"
-  task13_compose exec -T core curl --connect-timeout 3 --max-time 10 -fsS \
-    http://127.0.0.1:8787/workspaces \
+  task13_authenticated_get workspaces \
     | grep -Fq 'Task 13 Smoke' || task13_fail "initial workspace is unavailable"
 }
 
@@ -939,8 +1192,8 @@ task13_registry_lifecycle() {
   task13_commit_registry_change 'Update Task 13 workspace metadata'
   task13_write_environment /fixtures/remote.git
   task13_compose_logged "online Compose recreation" up --detach --force-recreate --wait --wait-timeout 120
-  task13_compose exec -T core curl --connect-timeout 3 --max-time 15 -fsS -X POST     http://127.0.0.1:8787/workspace-registry/pull >/dev/null
-  task13_compose exec -T core curl --connect-timeout 3 --max-time 10 -fsS     http://127.0.0.1:8787/workspaces     | grep -Fq 'Task 13 Smoke Updated' || task13_fail "valid Git update was not activated"
+  task13_authenticated_post workspace-registry/pull >/dev/null
+  task13_authenticated_get workspaces | grep -Fq 'Task 13 Smoke Updated' || task13_fail "valid Git update was not activated"
   valid_head="$(task13_active_registry_head)"
   [[ "$valid_head" =~ ^[0-9a-f]{40}$ && "$valid_head" != "$TASK13_INITIAL_HEAD" ]]     || task13_fail "valid Git update did not advance the registry head"
   TASK13_INITIAL_HEAD="$valid_head"
@@ -950,7 +1203,7 @@ task13_registry_lifecycle() {
 '
   printf 'guide v2\n' >"$TASK13_SEED/$TASK13_WORKSPACE_ID/evidence/guide.md"
   task13_commit_registry_change 'Update Task 13 workspace evidence only'
-  task13_compose exec -T core curl --connect-timeout 3 --max-time 15 -fsS -X POST     http://127.0.0.1:8787/workspace-registry/pull >/dev/null
+  task13_authenticated_post workspace-registry/pull >/dev/null
   evidence_head="$(task13_active_registry_head)"
   [[ "$evidence_head" =~ ^[0-9a-f]{40}$ && "$evidence_head" != "$valid_head" ]]     || task13_fail "content-only Git Evidence update did not advance the registry head"
   TASK13_INITIAL_HEAD="$evidence_head"
@@ -960,14 +1213,14 @@ task13_registry_lifecycle() {
 '
   task13_replace_once "$TASK13_SEED/thoth-workspaces.yaml"     'name: Task 13 Smoke Updated' 'name: Task 13 Smoke Drift'
   task13_commit_registry_change 'Break Task 13 workspace metadata parity'
-  if task13_compose exec -T core curl --connect-timeout 3 --max-time 15 -fsS -X POST     http://127.0.0.1:8787/workspace-registry/pull >>"$TASK13_LOG" 2>&1; then
+  if task13_authenticated_post workspace-registry/pull >>"$TASK13_LOG" 2>&1; then
     task13_fail "registry accepted catalog/descriptor metadata mismatch"
   fi
   [[ "$(task13_active_registry_head)" == "$TASK13_INITIAL_HEAD" ]]     || task13_fail "metadata mismatch replaced the valid registry head"
-  task13_compose exec -T core curl --connect-timeout 3 --max-time 10 -fsS     http://127.0.0.1:8787/workspaces     | grep -Fq 'Task 13 Smoke Updated' || task13_fail "metadata mismatch displaced the valid workspace"
+  task13_authenticated_get workspaces | grep -Fq 'Task 13 Smoke Updated' || task13_fail "metadata mismatch displaced the valid workspace"
   task13_replace_once "$TASK13_SEED/thoth-workspaces.yaml"     'name: Task 13 Smoke Drift' 'name: Task 13 Smoke Updated'
   task13_commit_registry_change 'Restore Task 13 workspace metadata parity'
-  task13_compose exec -T core curl --connect-timeout 3 --max-time 15 -fsS -X POST     http://127.0.0.1:8787/workspace-registry/pull >/dev/null
+  task13_authenticated_post workspace-registry/pull >/dev/null
   repaired_head="$(task13_active_registry_head)"
   [[ "$repaired_head" =~ ^[0-9a-f]{40}$ && "$repaired_head" != "$TASK13_INITIAL_HEAD" ]]     || task13_fail "metadata repair did not restore a fresh valid registry head"
   TASK13_INITIAL_HEAD="$repaired_head"
@@ -983,14 +1236,14 @@ task13_registry_lifecycle() {
   mkdir -p "$TASK13_SEED/orphan/evidence"
   printf 'orphan guide\n' >"$TASK13_SEED/orphan/evidence/guide.md"
   task13_commit_registry_change 'Add orphan Task 13 workspace directory'
-  if task13_compose exec -T core curl --connect-timeout 3 --max-time 15 -fsS -X POST     http://127.0.0.1:8787/workspace-registry/pull >>"$TASK13_LOG" 2>&1; then
+  if task13_authenticated_post workspace-registry/pull >>"$TASK13_LOG" 2>&1; then
     task13_fail "registry accepted orphan Task 13 descriptor directory"
   fi
   [[ "$(task13_active_registry_head)" == "$TASK13_INITIAL_HEAD" ]]     || task13_fail "orphan descriptor directory replaced the valid registry head"
-  task13_compose exec -T core curl --connect-timeout 3 --max-time 10 -fsS     http://127.0.0.1:8787/workspaces     | grep -Fq 'Task 13 Smoke Updated' || task13_fail "orphan descriptor displaced the valid workspace"
+  task13_authenticated_get workspaces | grep -Fq 'Task 13 Smoke Updated' || task13_fail "orphan descriptor displaced the valid workspace"
   rm -rf "$TASK13_SEED/orphan"
   task13_commit_registry_change 'Remove orphan Task 13 workspace directory'
-  task13_compose exec -T core curl --connect-timeout 3 --max-time 15 -fsS -X POST     http://127.0.0.1:8787/workspace-registry/pull >/dev/null
+  task13_authenticated_post workspace-registry/pull >/dev/null
   TASK13_INITIAL_HEAD="$(task13_active_registry_head)"
 
   printf '== Reject the retired flat workspace layout and retain the valid snapshot ==
@@ -999,11 +1252,11 @@ task13_registry_lifecycle() {
   cp "$TASK13_ROOT/scripts/fixtures/workspace-registry-task13.yaml"     "$TASK13_SEED/workspaces/$TASK13_WORKSPACE_ID.yaml"
   printf 'legacy guide\n' >"$TASK13_SEED/workspace-content/$TASK13_WORKSPACE_ID/evidence/guide.md"
   task13_commit_registry_change 'Reintroduce retired flat Task 13 workspace layout'
-  if task13_compose exec -T core curl --connect-timeout 3 --max-time 15 -fsS -X POST     http://127.0.0.1:8787/workspace-registry/pull >>"$TASK13_LOG" 2>&1; then
+  if task13_authenticated_post workspace-registry/pull >>"$TASK13_LOG" 2>&1; then
     task13_fail "registry accepted the retired flat Task 13 workspace layout"
   fi
   [[ "$(task13_active_registry_head)" == "$TASK13_INITIAL_HEAD" ]]     || task13_fail "retired flat workspace layout replaced the valid registry head"
-  task13_compose exec -T core curl --connect-timeout 3 --max-time 10 -fsS     http://127.0.0.1:8787/workspaces     | grep -Fq 'Task 13 Smoke Updated' || task13_fail "retired flat workspace layout displaced the valid workspace"
+  task13_authenticated_get workspaces | grep -Fq 'Task 13 Smoke Updated' || task13_fail "retired flat workspace layout displaced the valid workspace"
   task13_assert_sentinels
 }
 
@@ -1059,8 +1312,7 @@ task13_update_rollback() {
   task13_assert_sentinels
   task13_run_logged "post-rollback tht doctor" \
     "$TASK13_THT" --installation "$TASK13_INSTALLATION" pi doctor
-  task13_compose exec -T core curl --connect-timeout 3 --max-time 10 -fsS \
-    http://127.0.0.1:8787/workspaces \
+  task13_authenticated_get workspaces \
     | grep -Fq 'Task 13 Smoke' || task13_fail "rollback lost the active workspace"
 }
 
@@ -1174,6 +1426,7 @@ task13_cleanup() {
   fi
   task13_remove_labeled_container "${TASK13_BAD_CANDIDATE_CONTAINER:-}" || cleanup_rc=1
   task13_remove_labeled_container "${TASK13_LLM_CONTAINER:-}" || cleanup_rc=1
+  task13_remove_labeled_container "${TASK13_OIDC_CONTAINER:-}" || cleanup_rc=1
   if [[ -n "${TASK13_PROJECT:-}" && -n "${TASK13_ROOT:-}" && -f "${TASK13_OVERRIDE:-}" ]]; then
     if task13_assert_project_ownership >>"${TASK13_LOG:-/dev/null}" 2>&1; then
       task13_compose_files
@@ -1304,6 +1557,40 @@ task13_self_test_server_workspace_diagnostics() {
     || task13_fail "server diagnostics did not sanitize response and core logs"
 }
 
+task13_self_test_core_startup_diagnostics() {
+  local output
+  TASK13_SECRET_VALUE="fixture-known-secret"
+
+  task13_compose() {
+    case "$*" in
+      "ps --all -q core") printf '%s\n' 'task13-core-id' ;;
+      "logs --no-color --tail 100 core")
+        printf '%s\n' \
+          'Error: EACCES: permission denied, mkdir /data/auth/sessions' \
+          'password=plain-secret token=fixture-known-secret' \
+          'secret path: /run/secrets/private-token' \
+          '    at createFileAuthSessionStore (/app/backend/dist/auth/session-store.js:101:9)'
+        ;;
+      *) task13_fail "startup diagnostics requested an unexpected Compose command: $*" ;;
+    esac
+  }
+  docker() {
+    [[ "$*" == "inspect --format {{.State.Status}}:{{.State.ExitCode}} task13-core-id" ]] \
+      || task13_fail "startup diagnostics requested an unexpected Docker command: $*"
+    printf '%s\n' 'exited:1'
+  }
+
+  output="$(task13_report_core_startup_failure 2>&1)"
+  unset -f task13_compose docker
+
+  [[ "$output" == 'Core startup cause: authentication state storage is unavailable (exit code 1).' ]] \
+    || task13_fail "startup diagnostics emitted a non-allowlisted cause: $output"
+  for leaked in EACCES permission /data/auth /run/secrets plain-secret fixture-known-secret \
+    createFileAuthSessionStore session-store.js; do
+    [[ "$output" != *"$leaked"* ]] || task13_fail "startup diagnostics leaked $leaked"
+  done
+}
+
 task13_self_test_cleanup_ownership() {
   local calls foreign_error owned_name foreign_name
   calls="$(mktemp "${TMPDIR:-/tmp}/thothii-task13-cleanup-contract.XXXXXX")"
@@ -1664,6 +1951,7 @@ task13_self_test_source_contract() {
 
 task13_self_test() {
   task13_self_test_sanitizer
+  task13_self_test_core_startup_diagnostics
   task13_self_test_server_workspace_diagnostics
   task13_self_test_cleanup_ownership
   task13_self_test_image_cleanup_ownership
@@ -1695,6 +1983,7 @@ task13_self_test_case() {
     windows) task13_self_test_windows_release_contract ;;
     server) task13_self_test_server_release_contract ;;
     server-diagnostics) task13_self_test_server_workspace_diagnostics ;;
+    startup-diagnostics) task13_self_test_core_startup_diagnostics ;;
     *) task13_fail "unknown Task 13 self-test case: $1" ;;
   esac
 }
@@ -1777,8 +2066,12 @@ task13_initialize() {
   TASK13_PI_MODELS="$TASK13_TMP/models.json"
   TASK13_PI_SETTINGS="$TASK13_TMP/pi-settings.json"
   TASK13_LLM_SERVER="$TASK13_TMP/fake-llm.mjs"
+  TASK13_OIDC_SERVER="$TASK13_TMP/fake-oidc.mjs"
+  TASK13_OIDC_CERT="$TASK13_TMP/fake-oidc-cert.pem"
+  TASK13_OIDC_KEY="$TASK13_TMP/fake-oidc-key.pem"
   TASK13_THT_DIR="$TASK13_TMP/tht"
   TASK13_LLM_CONTAINER="$TASK13_PROJECT-llm"
+  TASK13_OIDC_CONTAINER="$TASK13_PROJECT-oidc"
   TASK13_BAD_CANDIDATE_CONTAINER="$TASK13_PROJECT-bad-candidate"
   TASK13_CORE_IMAGE="task13-core-$TASK13_RUN_ID:local"
   TASK13_FRONTEND_IMAGE="task13-frontend-$TASK13_RUN_ID:local"
@@ -1799,7 +2092,7 @@ task13_initialize() {
 }
 
 task13_require_tools() {
-  for command in bash git docker curl node sed awk grep rg sort; do
+  for command in bash git docker curl node openssl python3 sed awk grep rg sort; do
     command -v "$command" >/dev/null 2>&1 || task13_fail "$command is required"
   done
   task13_run_logged "Docker daemon readiness" docker info
@@ -1823,6 +2116,7 @@ task13_smoke_main() {
   task13_assert_project_ownership
   task13_assert_built_image_ownership
   task13_assert_runtime
+  task13_assert_local_restore_reauthentication
   task13_prepare_persistence
   if [[ "$mode" == full ]]; then
     task13_registry_lifecycle
diff --git a/tools/tht/internal/backup/create.go b/tools/tht/internal/backup/create.go
index 080e6443..86acf36e 100644
--- a/tools/tht/internal/backup/create.go
+++ b/tools/tht/internal/backup/create.go
@@ -457,26 +457,6 @@ func inspectRequiredVolumes(ctx context.Context, runner archiveRunner, rendered
 }
 
 func imageIdentities(ctx context.Context, installation config.Installation, runner archiveRunner, rendered renderedCompose) ([]ImageIdentity, error) {
-	result, err := runner.Run(ctx, installation.ComposeArgs("images", "--format", "json"), nil)
-	if err != nil {
-		return nil, dockerError("inspect image identities", result, err)
-	}
-	ids := map[string]string{}
-	decoder := json.NewDecoder(strings.NewReader(result.Stdout))
-	for {
-		var item struct {
-			Service string `json:"Service"`
-			ID      string `json:"ID"`
-		}
-		err := decoder.Decode(&item)
-		if errors.Is(err, io.EOF) {
-			break
-		}
-		if err != nil || item.Service == "" {
-			return nil, errors.New("Docker Compose returned invalid image identities")
-		}
-		ids[item.Service] = item.ID
-	}
 	services := make([]string, 0, len(rendered.Services))
 	for name, definition := range rendered.Services {
 		if definition.Image != "" {
@@ -486,11 +466,70 @@ func imageIdentities(ctx context.Context, installation config.Installation, runn
 	sort.Strings(services)
 	images := make([]ImageIdentity, 0, len(services))
 	for _, name := range services {
-		images = append(images, ImageIdentity{Service: name, Reference: rendered.Services[name].Image, ID: ids[name]})
+		result, err := runner.Run(ctx, installation.ComposeArgs("images", "--format", "json", name), nil)
+		if err != nil {
+			return nil, dockerError("inspect image identities", result, err)
+		}
+		inspected, err := decodeComposeImageIdentities(result.Stdout)
+		if err != nil {
+			return nil, err
+		}
+		matching := make([]composeImageIdentity, 0, len(inspected))
+		for _, item := range inspected {
+			if item.Service == "" || item.Service == name {
+				matching = append(matching, item)
+			}
+		}
+		if len(matching) > 1 {
+			return nil, errors.New("Docker Compose returned invalid image identities")
+		}
+		id := ""
+		if len(matching) == 1 {
+			id = matching[0].ID
+		}
+		images = append(images, ImageIdentity{Service: name, Reference: rendered.Services[name].Image, ID: id})
 	}
 	return images, nil
 }
 
+type composeImageIdentity struct {
+	Service       string `json:"Service"`
+	ContainerName string `json:"ContainerName"`
+	ID            string `json:"ID"`
+}
+
+func decodeComposeImageIdentities(value string) ([]composeImageIdentity, error) {
+	trimmed := strings.TrimSpace(value)
+	if trimmed == "" {
+		return nil, nil
+	}
+	var identities []composeImageIdentity
+	if strings.HasPrefix(trimmed, "[") {
+		if json.Unmarshal([]byte(trimmed), &identities) != nil {
+			return nil, errors.New("Docker Compose returned invalid image identities")
+		}
+	} else {
+		decoder := json.NewDecoder(strings.NewReader(trimmed))
+		for {
+			var item composeImageIdentity
+			err := decoder.Decode(&item)
+			if errors.Is(err, io.EOF) {
+				break
+			}
+			if err != nil {
+				return nil, errors.New("Docker Compose returned invalid image identities")
+			}
+			identities = append(identities, item)
+		}
+	}
+	for _, item := range identities {
+		if item.ID == "" || item.Service == "" && item.ContainerName == "" {
+			return nil, errors.New("Docker Compose returned invalid image identities")
+		}
+	}
+	return identities, nil
+}
+
 func installationRunning(ctx context.Context, installation config.Installation, runner archiveRunner) (bool, error) {
 	result, err := runner.Run(ctx, installation.ComposeArgs("ps", "--all", "--format", "json"), nil)
 	if err != nil {
diff --git a/tools/tht/internal/backup/create_test.go b/tools/tht/internal/backup/create_test.go
index 5ea50a3e..2d9bd9f1 100644
--- a/tools/tht/internal/backup/create_test.go
+++ b/tools/tht/internal/backup/create_test.go
@@ -23,6 +23,32 @@ import (
 
 var requiredTestVolumes = []string{"settings", "pi-state", "workspace-registry", "workspace-secrets", "sessions", "qdrant-data", "embedding-models"}
 
+func TestDecodeComposeImageIdentitiesAcceptsArrayAndStreamingJSON(t *testing.T) {
+	for name, input := range map[string]string{
+		"array":     `[{"ContainerName":"project-core-1","ID":"sha256:core"},{"ContainerName":"project-frontend-1","ID":"sha256:frontend"}]`,
+		"streaming": "{\"Service\":\"core\",\"ID\":\"sha256:core\"}\n{\"Service\":\"frontend\",\"ID\":\"sha256:frontend\"}\n",
+	} {
+		t.Run(name, func(t *testing.T) {
+			identities, err := decodeComposeImageIdentities(input)
+			if err != nil {
+				t.Fatal(err)
+			}
+			if len(identities) != 2 || identities[0].ID != "sha256:core" || identities[1].ID != "sha256:frontend" {
+				t.Fatalf("image identities = %#v", identities)
+			}
+		})
+	}
+}
+
+func TestDecodeComposeImageIdentitiesAcceptsNoContainerForProfiledService(t *testing.T) {
+	for _, input := range []string{"", "[]"} {
+		identities, err := decodeComposeImageIdentities(input)
+		if err != nil || len(identities) != 0 {
+			t.Fatalf("decodeComposeImageIdentities(%q) = %#v, %v", input, identities, err)
+		}
+	}
+}
+
 func TestCreateWritesManifestLastWithConfigurationMetadataAndSevenVolumes(t *testing.T) {
 	fixture := newBackupFixture(t, "local")
 	output := filepath.Join(t.TempDir(), "custom.zip")
diff --git a/tools/tht/internal/backup/preflight.go b/tools/tht/internal/backup/preflight.go
index bb8fa20d..e5658b26 100644
--- a/tools/tht/internal/backup/preflight.go
+++ b/tools/tht/internal/backup/preflight.go
@@ -61,13 +61,15 @@ type PreflightDependencies struct {
 
 // ArchiveEntryMetadata is safe restore metadata. It intentionally contains no archive payload.
 type ArchiveEntryMetadata struct {
-	Path      string
-	Kind      string
-	Owner     string
-	Size      int64
-	SHA256    string
-	Mode      uint32
-	Sensitive bool
+	Path        string
+	Kind        string
+	Owner       string
+	LogicalName string
+	SourcePath  string
+	Size        int64
+	SHA256      string
+	Mode        uint32
+	Sensitive   bool
 }
 
 // PreflightResult is the validated, non-mutating input for a future restore transaction.
@@ -534,6 +536,8 @@ func reconcileArchiveEntries(ctx context.Context, manifest Manifest, entries map
 		requiredBytes += uint64(actual.metadata.Size)
 		actual.metadata.Kind = entry.Kind
 		actual.metadata.Owner = entry.Owner
+		actual.metadata.LogicalName = entry.LogicalName
+		actual.metadata.SourcePath = entry.SourcePath
 		actual.metadata.Sensitive = entry.Sensitive
 		metadata = append(metadata, actual.metadata)
 		delete(entries, entry.Path)
diff --git a/tools/tht/internal/backup/preflight_test.go b/tools/tht/internal/backup/preflight_test.go
index b2672ea3..8b9f6f18 100644
--- a/tools/tht/internal/backup/preflight_test.go
+++ b/tools/tht/internal/backup/preflight_test.go
@@ -325,6 +325,7 @@ type preflightArchiveSpec struct {
 	entries        []preflightArchiveEntry
 	rawEntries     []preflightRawArchiveEntry
 	rawManifest    []byte
+	volumes        []VolumeMetadata
 }
 
 type preflightArchiveEntry struct {
@@ -337,6 +338,9 @@ type preflightArchiveEntry struct {
 	mode         os.FileMode
 	manifestMode *uint32
 	method       uint16
+	owner        string
+	logicalName  string
+	sourcePath   string
 }
 
 type preflightRawArchiveEntry struct {
@@ -374,6 +378,7 @@ func writePreflightArchive(t *testing.T, archivePath string, spec preflightArchi
 		SchemaVersion: spec.schemaVersion, InstallationID: spec.installationID,
 		CreatedAt: time.Date(2026, 8, 16, 10, 0, 0, 0, time.UTC), SourceRevision: testRevision,
 		IncludesSecrets: spec.includeSecrets, ComposeProject: "thothii-test",
+		Volumes: append([]VolumeMetadata(nil), spec.volumes...),
 	}
 	for _, entry := range spec.entries {
 		checksum := entry.checksum
@@ -384,11 +389,18 @@ func writePreflightArchive(t *testing.T, archivePath string, spec preflightArchi
 		if kind == "" {
 			kind = EntryFile
 		}
-		sourcePath := ""
-		owner := "installation"
+		sourcePath := entry.sourcePath
+		owner := entry.owner
+		if owner == "" {
+			owner = "installation"
+		}
 		if kind == EntryExternalSecret {
-			sourcePath = "/protected/secret"
-			owner = "external-secret"
+			if sourcePath == "" {
+				sourcePath = "/protected/secret"
+			}
+			if entry.owner == "" {
+				owner = "external-secret"
+			}
 		}
 		mode := uint32(entry.mode.Perm())
 		if mode == 0 {
@@ -397,7 +409,7 @@ func writePreflightArchive(t *testing.T, archivePath string, spec preflightArchi
 		if entry.manifestMode != nil {
 			mode = *entry.manifestMode
 		}
-		manifest.Entries = append(manifest.Entries, Entry{Path: entry.path, Kind: kind, Owner: owner, SourcePath: sourcePath, SHA256: checksum, Size: int64(len(entry.body)), Mode: mode, Archived: true, Sensitive: entry.sensitive})
+		manifest.Entries = append(manifest.Entries, Entry{Path: entry.path, Kind: kind, Owner: owner, LogicalName: entry.logicalName, SourcePath: sourcePath, SHA256: checksum, Size: int64(len(entry.body)), Mode: mode, Archived: true, Sensitive: entry.sensitive})
 	}
 	manifestBytes, err := manifest.JSON()
 	if err != nil {
diff --git a/tools/tht/internal/backup/restore.go b/tools/tht/internal/backup/restore.go
index 609d8887..ffca69de 100644
--- a/tools/tht/internal/backup/restore.go
+++ b/tools/tht/internal/backup/restore.go
@@ -42,10 +42,11 @@ type restoreDependencies struct {
 	verify                   map[string]restoreVerify
 }
 
-// Restore runs the host transaction. Concrete host dependencies are intentionally kept outside
-// the deterministic core so callers cannot bypass its preflight and checkpoint boundaries.
+// Restore runs the host transaction through the same concrete Docker/filesystem boundaries used
+// by backup creation. The injectable core below exists only to make every failure boundary
+// deterministic in tests.
 func Restore(ctx context.Context, installation config.Installation, request RestoreRequest) (RestoreResult, error) {
-	return RestoreResult{}, errors.New("restore host dependencies are unavailable")
+	return restoreWithDependencies(ctx, installation, request, productionRestoreDependencies(installation))
 }
 
 func restoreWithDependencies(ctx context.Context, installation config.Installation, request RestoreRequest, deps restoreDependencies) (result RestoreResult, resultErr error) {
@@ -113,9 +114,6 @@ func restoreWithDependencies(ctx context.Context, installation config.Installati
 		members[member.Name] = member
 	}
 	for _, entry := range preflight.Entries {
-		if entry.Kind == EntryVolume {
-			continue
-		}
 		member := members[entry.Path]
 		if member == nil {
 			return result, fmt.Errorf("verified archive is missing %q", entry.Path)
@@ -125,7 +123,17 @@ func restoreWithDependencies(ctx context.Context, installation config.Installati
 			return result, fmt.Errorf("open verified archive member %q: %w", entry.Path, openErr)
 		}
 		mutated = true
-		restoreErr := deps.restoreFile(ctx, installation, entry, stream)
+		var restoreErr error
+		if entry.Kind == EntryVolume {
+			volume, found := restoreVolumeMetadata(preflight.Manifest, entry.LogicalName)
+			if !found {
+				_ = stream.Close()
+				return result, errors.New("verified volume metadata is incomplete")
+			}
+			restoreErr = deps.restoreVolume(ctx, installation, volume, stream)
+		} else {
+			restoreErr = deps.restoreFile(ctx, installation, entry, stream)
+		}
 		closeErr := stream.Close()
 		if restoreErr != nil {
 			return result, restoreErr
@@ -156,13 +164,25 @@ func restoreWithDependencies(ctx context.Context, installation config.Installati
 	return result, nil
 }
 
+func restoreVolumeMetadata(manifest Manifest, logicalName string) (VolumeMetadata, bool) {
+	if logicalName == "" {
+		return VolumeMetadata{}, false
+	}
+	for _, volume := range manifest.Volumes {
+		if volume.LogicalName == logicalName {
+			return volume, true
+		}
+	}
+	return VolumeMetadata{}, false
+}
+
 // resetAuthenticationState clears browser sessions and pending OIDC transactions without touching
 // installation-global auth.yaml or users.yaml. The command runs as the unprivileged core user so
 // the recreated state root is private to the service on both the local volume and server /data bind.
 func resetAuthenticationState(ctx context.Context, installation config.Installation, runner archiveRunner) error {
 	result, err := runner.Run(ctx, installation.ComposeArgs(
 		"run", "--rm", "--no-deps", "--no-TTY", "--entrypoint", "sh", "core", "-ceu",
-		"rm -rf /data/auth && install -d -m 0700 /data/auth /data/auth/sessions /data/auth/oidc",
+		"find /data/auth -mindepth 1 -maxdepth 1 -exec rm -rf -- {} + && install -d -m 0700 /data/auth /data/auth/sessions /data/auth/oidc && test -z \"$(find /data/auth/sessions /data/auth/oidc -mindepth 1 -print -quit)\"",
 	), nil)
 	if err != nil {
 		return dockerError("reset authentication state", result, err)
diff --git a/tools/tht/internal/backup/restore_disk_unix.go b/tools/tht/internal/backup/restore_disk_unix.go
new file mode 100644
index 00000000..4236076e
--- /dev/null
+++ b/tools/tht/internal/backup/restore_disk_unix.go
@@ -0,0 +1,22 @@
+//go:build !windows
+
+package backup
+
+import (
+	"errors"
+
+	"golang.org/x/sys/unix"
+)
+
+func restoreFreeBytes(target string) (uint64, error) {
+	var statistics unix.Statfs_t
+	if err := unix.Statfs(target, &statistics); err != nil {
+		return 0, errors.New("restore filesystem capacity is unavailable")
+	}
+	blockSize := uint64(statistics.Bsize)
+	available := uint64(statistics.Bavail)
+	if blockSize != 0 && available > ^uint64(0)/blockSize {
+		return 0, errors.New("restore filesystem capacity is invalid")
+	}
+	return blockSize * available, nil
+}
diff --git a/tools/tht/internal/backup/restore_disk_windows.go b/tools/tht/internal/backup/restore_disk_windows.go
new file mode 100644
index 00000000..b9516059
--- /dev/null
+++ b/tools/tht/internal/backup/restore_disk_windows.go
@@ -0,0 +1,21 @@
+//go:build windows
+
+package backup
+
+import (
+	"errors"
+
+	"golang.org/x/sys/windows"
+)
+
+func restoreFreeBytes(target string) (uint64, error) {
+	path, err := windows.UTF16PtrFromString(target)
+	if err != nil {
+		return 0, errors.New("restore filesystem capacity is unavailable")
+	}
+	var available uint64
+	if err := windows.GetDiskFreeSpaceEx(path, &available, nil, nil); err != nil {
+		return 0, errors.New("restore filesystem capacity is unavailable")
+	}
+	return available, nil
+}
diff --git a/tools/tht/internal/backup/restore_file_unix.go b/tools/tht/internal/backup/restore_file_unix.go
new file mode 100644
index 00000000..310117d8
--- /dev/null
+++ b/tools/tht/internal/backup/restore_file_unix.go
@@ -0,0 +1,121 @@
+//go:build !windows
+
+package backup
+
+import (
+	"crypto/rand"
+	"encoding/hex"
+	"errors"
+	"io"
+	"os"
+	"path/filepath"
+	"strings"
+
+	"github.com/aritmolab/thothii/tools/tht/internal/safeio"
+	"golang.org/x/sys/unix"
+)
+
+type restoreTargetIdentity struct {
+	exists bool
+	device uint64
+	inode  uint64
+}
+
+func replaceRestoreFile(target string, contents []byte, mode os.FileMode) error {
+	if safeio.ValidateCanonicalPath(target) != nil || mode&os.ModeType != 0 || mode.Perm() == 0 {
+		return safeio.ErrUnsafeFile
+	}
+	components := strings.Split(strings.TrimPrefix(target, string(os.PathSeparator)), string(os.PathSeparator))
+	if len(components) < 2 || components[0] == "" || components[len(components)-1] == "" {
+		return safeio.ErrUnsafeFile
+	}
+	directory, err := unix.Open(string(os.PathSeparator), unix.O_RDONLY|unix.O_CLOEXEC|unix.O_DIRECTORY, 0)
+	if err != nil {
+		return safeio.ErrUnsafeFile
+	}
+	defer unix.Close(directory)
+	for _, component := range components[:len(components)-1] {
+		next, openErr := unix.Openat(directory, component, unix.O_RDONLY|unix.O_CLOEXEC|unix.O_DIRECTORY|unix.O_NOFOLLOW, 0)
+		if openErr != nil {
+			return safeio.ErrUnsafeFile
+		}
+		unix.Close(directory)
+		directory = next
+	}
+	name := components[len(components)-1]
+	identity, err := inspectRestoreTargetAt(directory, name)
+	if err != nil {
+		return safeio.ErrUnsafeFile
+	}
+	temporary, err := writeRestoreTemporaryAt(directory, contents, mode.Perm())
+	if err != nil {
+		return safeio.ErrUnsafeFile
+	}
+	defer func() { _ = unix.Unlinkat(directory, temporary, 0) }()
+	current, err := inspectRestoreTargetAt(directory, name)
+	if err != nil || current != identity {
+		return safeio.ErrUnsafeFile
+	}
+	if err := unix.Renameat(directory, temporary, directory, name); err != nil {
+		return safeio.ErrUnsafeFile
+	}
+	temporary = ""
+	if err := unix.Fsync(directory); err != nil {
+		return safeio.ErrUnsafeFile
+	}
+	return nil
+}
+
+func inspectRestoreTargetAt(directory int, name string) (restoreTargetIdentity, error) {
+	var status unix.Stat_t
+	err := unix.Fstatat(directory, name, &status, unix.AT_SYMLINK_NOFOLLOW)
+	if errors.Is(err, unix.ENOENT) {
+		return restoreTargetIdentity{}, nil
+	}
+	if err != nil || status.Mode&unix.S_IFMT != unix.S_IFREG || status.Nlink != 1 {
+		return restoreTargetIdentity{}, safeio.ErrUnsafeFile
+	}
+	return restoreTargetIdentity{exists: true, device: uint64(status.Dev), inode: status.Ino}, nil
+}
+
+func writeRestoreTemporaryAt(directory int, contents []byte, mode os.FileMode) (string, error) {
+	for attempt := 0; attempt < 16; attempt++ {
+		random := make([]byte, 8)
+		if _, err := rand.Read(random); err != nil {
+			return "", err
+		}
+		name := ".tht-restore-" + hex.EncodeToString(random) + ".tmp"
+		descriptor, err := unix.Openat(directory, name, unix.O_WRONLY|unix.O_CREAT|unix.O_EXCL|unix.O_CLOEXEC|unix.O_NOFOLLOW, uint32(mode))
+		if errors.Is(err, unix.EEXIST) {
+			continue
+		}
+		if err != nil {
+			return "", err
+		}
+		file := os.NewFile(uintptr(descriptor), filepath.Base(name))
+		if file == nil {
+			unix.Close(descriptor)
+			return "", safeio.ErrUnsafeFile
+		}
+		if err := file.Chmod(mode); err == nil {
+			var written int
+			written, err = file.Write(contents)
+			if err == nil && written != len(contents) {
+				err = io.ErrShortWrite
+			}
+		}
+		if err == nil {
+			err = file.Sync()
+		}
+		closeErr := file.Close()
+		if err == nil {
+			err = closeErr
+		}
+		if err != nil {
+			_ = unix.Unlinkat(directory, name, 0)
+			return "", err
+		}
+		return name, nil
+	}
+	return "", safeio.ErrUnsafeFile
+}
diff --git a/tools/tht/internal/backup/restore_file_windows.go b/tools/tht/internal/backup/restore_file_windows.go
new file mode 100644
index 00000000..71572789
--- /dev/null
+++ b/tools/tht/internal/backup/restore_file_windows.go
@@ -0,0 +1,59 @@
+//go:build windows
+
+package backup
+
+import (
+	"errors"
+	"os"
+	"path/filepath"
+
+	"github.com/aritmolab/thothii/tools/tht/internal/safeio"
+	"golang.org/x/sys/windows"
+)
+
+func replaceRestoreFile(target string, contents []byte, mode os.FileMode) error {
+	if safeio.ValidateCanonicalPath(target) != nil || mode&os.ModeType != 0 || mode.Perm() == 0 {
+		return safeio.ErrUnsafeFile
+	}
+	parent := filepath.Dir(target)
+	resolved, err := filepath.EvalSymlinks(parent)
+	if err != nil || resolved != parent || !safeWindowsRestoreTarget(target) {
+		return safeio.ErrUnsafeFile
+	}
+	temporary, err := os.CreateTemp(parent, ".tht-restore-*.tmp")
+	if err != nil {
+		return safeio.ErrUnsafeFile
+	}
+	temporaryPath := temporary.Name()
+	defer os.Remove(temporaryPath)
+	if err := temporary.Chmod(mode.Perm()); err == nil {
+		_, err = temporary.Write(contents)
+	}
+	if err == nil {
+		err = temporary.Sync()
+	}
+	closeErr := temporary.Close()
+	if err == nil {
+		err = closeErr
+	}
+	if err != nil || !safeWindowsRestoreTarget(target) {
+		return safeio.ErrUnsafeFile
+	}
+	from, fromErr := windows.UTF16PtrFromString(temporaryPath)
+	to, toErr := windows.UTF16PtrFromString(target)
+	if fromErr != nil || toErr != nil {
+		return safeio.ErrUnsafeFile
+	}
+	if err := windows.MoveFileEx(from, to, windows.MOVEFILE_REPLACE_EXISTING|windows.MOVEFILE_WRITE_THROUGH); err != nil {
+		return safeio.ErrUnsafeFile
+	}
+	return nil
+}
+
+func safeWindowsRestoreTarget(target string) bool {
+	info, err := os.Lstat(target)
+	if errors.Is(err, os.ErrNotExist) {
+		return true
+	}
+	return err == nil && info.Mode().IsRegular() && info.Mode()&os.ModeSymlink == 0
+}
diff --git a/tools/tht/internal/backup/restore_host.go b/tools/tht/internal/backup/restore_host.go
new file mode 100644
index 00000000..495161b3
--- /dev/null
+++ b/tools/tht/internal/backup/restore_host.go
@@ -0,0 +1,352 @@
+package backup
+
+import (
+	"context"
+	"crypto/rand"
+	"crypto/sha256"
+	"encoding/hex"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"io"
+	"os"
+	"path/filepath"
+	"strconv"
+	"strings"
+	"time"
+
+	"github.com/aritmolab/thothii/tools/tht/internal/compose"
+	"github.com/aritmolab/thothii/tools/tht/internal/config"
+	"github.com/aritmolab/thothii/tools/tht/internal/doctor"
+	"github.com/aritmolab/thothii/tools/tht/internal/lifecycle"
+	"github.com/aritmolab/thothii/tools/tht/internal/pi"
+	"github.com/aritmolab/thothii/tools/tht/internal/safeio"
+	"github.com/aritmolab/thothii/tools/tht/internal/service"
+)
+
+func productionRestoreDependencies(installation config.Installation) restoreDependencies {
+	runner := hostRunner{runner: compose.NewRunner(""), binary: "docker", profile: installation.Profile}
+	return restoreDependencies{
+		preflight: func(ctx context.Context, target config.Installation, request PreflightRequest) (PreflightResult, error) {
+			return Preflight(ctx, target, request, PreflightDependencies{
+				FreeBytes:                 restoreFreeBytes,
+				CheckOwnershipPermissions: validateRestoreTargets,
+				CheckVolumeMapping: func(ctx context.Context, target config.Installation, manifest Manifest) error {
+					return validateRestoreVolumes(ctx, target, manifest, runner)
+				},
+				CheckImageConfigCompatibility: func(ctx context.Context, target config.Installation, manifest Manifest) error {
+					return validateRestoreImages(ctx, target, manifest, runner)
+				},
+			})
+		},
+		checkpoint: func(ctx context.Context, target config.Installation, request CreateRequest) (Result, error) {
+			path, err := restoreCheckpointPath(target, time.Now().UTC())
+			if err != nil {
+				return Result{}, err
+			}
+			request.Output = path
+			return Create(ctx, target, request)
+		},
+		acquireLock: func(target config.Installation) (restoreLock, error) {
+			return lifecycle.Acquire(target)
+		},
+		runner:      runner,
+		sleep:       time.Sleep,
+		restoreFile: restoreFilePayload,
+		restoreVolume: func(ctx context.Context, _ config.Installation, volume VolumeMetadata, input io.Reader) error {
+			result, err := runner.Stream(ctx, volumeRestoreCommand(volume.Name), input, io.Discard)
+			if err != nil || result.ExitCode != 0 {
+				if err == nil {
+					err = errors.New("Docker volume helper returned a nonzero exit status")
+				}
+				return fmt.Errorf("restore volume %s: %w", volume.LogicalName, dockerError("stream volume", result, err))
+			}
+			return nil
+		},
+		resetAuthenticationState: resetAuthenticationState,
+		verify: map[string]restoreVerify{
+			"health":    verifyRestoreHealth,
+			"doctor":    verifyRestoreDoctor,
+			"pi":        verifyRestorePi,
+			"workspace": verifyRestoreWorkspace,
+		},
+	}
+}
+
+func restoreCheckpointPath(installation config.Installation, now time.Time) (string, error) {
+	suffix := make([]byte, 8)
+	if _, err := rand.Read(suffix); err != nil {
+		return "", errors.New("recovery checkpoint name is unavailable")
+	}
+	name := fmt.Sprintf("restore-checkpoint-%s-%s.zip", now.Format("20060102T150405.000000000Z"), hex.EncodeToString(suffix))
+	return filepath.Join(installation.ControlDirectory(), name), nil
+}
+
+func validateRestoreTargets(_ context.Context, installation config.Installation, manifest Manifest) error {
+	for _, entry := range manifest.Entries {
+		if entry.Kind == EntryVolume {
+			continue
+		}
+		if !entry.Archived {
+			if entry.Kind == EntrySecretReference || entry.Kind == EntryPreservationReference {
+				if err := validateRestoreReference(installation, entry); err != nil {
+					return err
+				}
+			}
+			continue
+		}
+		metadata := ArchiveEntryMetadata{
+			Path: entry.Path, Kind: entry.Kind, Owner: entry.Owner, LogicalName: entry.LogicalName,
+			SourcePath: entry.SourcePath, Size: entry.Size, SHA256: entry.SHA256, Mode: entry.Mode,
+			Sensitive: entry.Sensitive,
+		}
+		target, err := restoreFileTarget(installation, metadata)
+		if err != nil || !safeRestoreParent(target) {
+			return errors.New("restore target ownership or permissions are invalid")
+		}
+	}
+	return nil
+}
+
+func validateRestoreReference(installation config.Installation, entry Entry) error {
+	metadata := ArchiveEntryMetadata{
+		Path: entry.Path, Kind: entry.Kind, Owner: entry.Owner, SourcePath: entry.SourcePath,
+		Size: entry.Size, SHA256: entry.SHA256, Mode: entry.Mode, Sensitive: entry.Sensitive,
+	}
+	if entry.Kind == EntryPreservationReference {
+		return nil
+	}
+	if _, err := restoreExternalTarget(installation, metadata); err != nil {
+		return errors.New("restore external prerequisite is invalid")
+	}
+	contents, err := safeio.ReadCanonicalRegular(entry.SourcePath, entry.Size)
+	if err != nil || int64(len(contents)) != entry.Size {
+		return errors.New("restore external prerequisite is unavailable or unsafe")
+	}
+	digest := sha256.Sum256(contents)
+	if "sha256:"+hex.EncodeToString(digest[:]) != entry.SHA256 {
+		return errors.New("restore external prerequisite has changed")
+	}
+	return nil
+}
+
+func validateRestoreVolumes(ctx context.Context, installation config.Installation, manifest Manifest, runner archiveRunner) error {
+	if len(manifest.Volumes) != len(requiredVolumes) {
+		return errors.New("backup volume set is incomplete")
+	}
+	rendered, err := renderedConfiguration(ctx, installation, runner)
+	if err != nil {
+		return err
+	}
+	current, err := inspectRequiredVolumes(ctx, runner, rendered)
+	if err != nil {
+		return err
+	}
+	archived := make(map[string]VolumeMetadata, len(manifest.Volumes))
+	for _, volume := range manifest.Volumes {
+		archived[volume.LogicalName] = volume
+	}
+	for _, volume := range current {
+		previous, found := archived[volume.LogicalName]
+		if !found || previous.Name != volume.Name || previous.Driver != volume.Driver {
+			return errors.New("backup volume ownership does not match the installation")
+		}
+		if volume.Labels["com.docker.compose.project"] != installation.ProjectName() {
+			return errors.New("current volume is not owned by the installation")
+		}
+	}
+	return nil
+}
+
+func validateRestoreImages(ctx context.Context, installation config.Installation, manifest Manifest, runner archiveRunner) error {
+	rendered, err := renderedConfiguration(ctx, installation, runner)
+	if err != nil {
+		return err
+	}
+	for _, image := range manifest.Images {
+		serviceDefinition, found := rendered.Services[image.Service]
+		if !found || serviceDefinition.Image == "" || serviceDefinition.Image != image.Reference {
+			return errors.New("backup image configuration does not match the installation")
+		}
+	}
+	return nil
+}
+
+func restoreFilePayload(_ context.Context, installation config.Installation, entry ArchiveEntryMetadata, input io.Reader) error {
+	if entry.Size < 0 || uint64(entry.Size) > defaultPreflightMaxUncompressedBytes {
+		return errors.New("restore file size is invalid")
+	}
+	contents, err := io.ReadAll(io.LimitReader(input, entry.Size+1))
+	if err != nil || int64(len(contents)) != entry.Size {
+		return errors.New("restore file payload is invalid")
+	}
+	target, err := restoreFileTarget(installation, entry)
+	if err != nil {
+		return err
+	}
+	if err := replaceRestoreFile(target, contents, os.FileMode(entry.Mode)); err != nil {
+		return errors.New("restore file could not be replaced safely")
+	}
+	return nil
+}
+
+func restoreFileTarget(installation config.Installation, entry ArchiveEntryMetadata) (string, error) {
+	if entry.Kind == EntryExternalSecret {
+		return restoreExternalTarget(installation, entry)
+	}
+	if entry.Kind != EntryFile {
+		return "", errors.New("restore file kind is unsupported")
+	}
+	switch entry.Path {
+	case "configuration/installation/thothii-installation.yaml":
+		return installation.Path, nil
+	case "configuration/environment/operator.env":
+		return installation.EnvFile, nil
+	case "configuration/pi/models.json":
+		return filepath.Join(installation.ProjectDirectory, "deploy", "pi", "models.json"), nil
+	case "configuration/pi/settings.json":
+		return filepath.Join(installation.ProjectDirectory, "deploy", "pi", "settings.json"), nil
+	case "configuration/generated/current-image.yaml":
+		return installation.CurrentImageOverridePath(), nil
+	}
+	if strings.HasPrefix(entry.Path, "configuration/overrides/") {
+		name := strings.TrimPrefix(entry.Path, "configuration/overrides/")
+		indexText, base, found := strings.Cut(name, "-")
+		index, parseErr := strconv.Atoi(indexText)
+		if !found || parseErr != nil || len(indexText) != 2 || index < 0 || index >= len(installation.Overrides) || filepath.Base(installation.Overrides[index]) != base {
+			return "", errors.New("restore override target is invalid")
+		}
+		return installation.Overrides[index], nil
+	}
+	if strings.HasPrefix(entry.Owner, "preservation-root:") && strings.HasPrefix(entry.Path, "preservation/") {
+		variable := strings.TrimPrefix(entry.Owner, "preservation-root:")
+		allowed := variable == "THT_DATA_ROOT" || variable == "THT_PI_STATE_ROOT" || variable == "THT_WORKSPACE_REGISTRY_ROOT"
+		parts := strings.SplitN(entry.Path, "/", 3)
+		root, rootErr := installation.EnvironmentValue(variable)
+		if !allowed || len(parts) != 3 || rootErr != nil || root == "" {
+			return "", errors.New("restore preservation target is invalid")
+		}
+		target := filepath.Join(root, filepath.FromSlash(parts[2]))
+		relative, relErr := filepath.Rel(root, target)
+		if relErr != nil || relative == ".." || strings.HasPrefix(relative, ".."+string(filepath.Separator)) {
+			return "", errors.New("restore preservation target escapes its root")
+		}
+		return target, nil
+	}
+	return "", errors.New("restore file target is not declared")
+}
+
+func restoreExternalTarget(installation config.Installation, entry ArchiveEntryMetadata) (string, error) {
+	if entry.SourcePath == "" || filepath.Clean(entry.SourcePath) != entry.SourcePath || !filepath.IsAbs(entry.SourcePath) {
+		return "", errors.New("restore external target is invalid")
+	}
+	if entry.Owner == "external-secret" {
+		paths, err := installation.SecretFiles()
+		if err != nil {
+			return "", errors.New("restore external secret declarations are unavailable")
+		}
+		for _, path := range paths {
+			if path == entry.SourcePath {
+				return path, nil
+			}
+		}
+		return "", errors.New("restore external secret target is not declared")
+	}
+	if entry.Owner == "authentication-configuration" {
+		for _, name := range []string{"auth.yaml", "users.yaml"} {
+			path := filepath.Join(installation.AuthenticationDirectory(), name)
+			if entry.SourcePath == path {
+				return path, nil
+			}
+		}
+	}
+	return "", errors.New("restore external target owner is invalid")
+}
+
+func safeRestoreParent(target string) bool {
+	if target == "" || !filepath.IsAbs(target) || filepath.Clean(target) != target {
+		return false
+	}
+	parent := filepath.Dir(target)
+	resolved, err := filepath.EvalSymlinks(parent)
+	if err != nil || resolved != parent {
+		return false
+	}
+	info, err := os.Stat(parent)
+	if err != nil || !info.IsDir() {
+		return false
+	}
+	if targetInfo, err := os.Lstat(target); err == nil {
+		return targetInfo.Mode().IsRegular() && targetInfo.Mode()&os.ModeSymlink == 0
+	} else {
+		return errors.Is(err, os.ErrNotExist)
+	}
+}
+
+func volumeRestoreCommand(volume string) []string {
+	return []string{
+		"run", "--rm", "--network", "none", "--mount", "type=volume,src=" + volume + ",dst=/target",
+		helperImage, "sh", "-ceu",
+		"rm -rf -- /target/* /target/.[!.]* /target/..?*; tar --numeric-owner -C /target -xf -",
+	}
+}
+
+func restoreVerificationRunning(ctx context.Context, installation config.Installation, runner archiveRunner) (bool, error) {
+	return installationRunning(ctx, installation, runner)
+}
+
+func verifyRestoreHealth(ctx context.Context, installation config.Installation, runner archiveRunner) error {
+	running, err := restoreVerificationRunning(ctx, installation, runner)
+	if err != nil || !running {
+		return err
+	}
+	return service.WaitForHealthy(ctx, installation, runner)
+}
+
+func verifyRestoreDoctor(ctx context.Context, installation config.Installation, runner archiveRunner) error {
+	running, err := restoreVerificationRunning(ctx, installation, runner)
+	if err != nil {
+		return err
+	}
+	if !running {
+		result, configErr := runner.Run(ctx, installation.ComposeArgs("config", "--quiet"), nil)
+		if configErr != nil {
+			return dockerError("verify restored Compose configuration", result, configErr)
+		}
+		return nil
+	}
+	report, err := doctor.Run(ctx, installation, runner)
+	if err != nil {
+		return err
+	}
+	if !report.OK {
+		return errors.New("aggregate doctor did not pass after restore")
+	}
+	return nil
+}
+
+func verifyRestorePi(ctx context.Context, installation config.Installation, runner archiveRunner) error {
+	running, err := restoreVerificationRunning(ctx, installation, runner)
+	if err != nil || !running {
+		return err
+	}
+	return pi.Doctor(ctx, compose.InstallationRunner{Installation: installation, Runner: runner})
+}
+
+func verifyRestoreWorkspace(ctx context.Context, installation config.Installation, runner archiveRunner) error {
+	running, err := restoreVerificationRunning(ctx, installation, runner)
+	if err != nil || !running {
+		return err
+	}
+	result, err := runner.Run(ctx, installation.ComposeArgs(
+		"exec", "-T", "core", "curl", "-fsS", "--max-time", "5", "http://127.0.0.1:8787/workspaces",
+	), nil)
+	if err != nil {
+		return dockerError("inspect restored workspaces", result, err)
+	}
+	var workspaces []json.RawMessage
+	if json.Unmarshal([]byte(result.Stdout), &workspaces) != nil {
+		return errors.New("restored workspace inspection returned invalid JSON")
+	}
+	return nil
+}
diff --git a/tools/tht/internal/backup/restore_test.go b/tools/tht/internal/backup/restore_test.go
index 4600f4ed..3f9cde8e 100644
--- a/tools/tht/internal/backup/restore_test.go
+++ b/tools/tht/internal/backup/restore_test.go
@@ -1,6 +1,8 @@
 package backup
 
 import (
+	"archive/tar"
+	"bytes"
 	"context"
 	"errors"
 	"io"
@@ -13,6 +15,85 @@ import (
 	"github.com/aritmolab/thothii/tools/tht/internal/config"
 )
 
+func TestRestorePublicPathUsesConcreteProductionPreflight(t *testing.T) {
+	root := t.TempDir()
+	installation := config.Installation{
+		Path:             filepath.Join(root, "deploy", "local-dev", "thothii-installation.yaml"),
+		ProjectDirectory: root,
+	}
+	missing := filepath.Join(root, "missing.zip")
+
+	_, err := Restore(context.Background(), installation, RestoreRequest{Archive: missing, Confirm: true})
+
+	if err == nil || strings.Contains(err.Error(), "dependencies are unavailable") || !strings.Contains(err.Error(), "backup archive") {
+		t.Fatalf("Restore() error = %v, want production archive preflight", err)
+	}
+}
+
+func TestRestoreRestoresVerifiedVolumesInManifestOrderBeforeAuthenticationReset(t *testing.T) {
+	installation := preflightTestInstallation(t)
+	archive := filepath.Join(t.TempDir(), "restore-volumes.zip")
+	sessionsTar := safeRestoreTar(t, "session.txt", "session")
+	settingsTar := safeRestoreTar(t, "settings.json", "settings")
+	writePreflightArchive(t, archive, preflightArchiveSpec{
+		volumes: []VolumeMetadata{
+			{LogicalName: "sessions", Name: "project_sessions", Driver: "local"},
+			{LogicalName: "settings", Name: "project_settings", Driver: "local"},
+		},
+		entries: []preflightArchiveEntry{
+			{path: "configuration/operator.env", body: []byte("safe")},
+			{path: "volumes/settings.tar", body: settingsTar, kind: EntryVolume, owner: "volume:settings", logicalName: "settings"},
+			{path: "volumes/sessions.tar", body: sessionsTar, kind: EntryVolume, owner: "volume:sessions", logicalName: "sessions"},
+		},
+	})
+	runner := newBackupRunner(installation, false)
+	deps := restoreTestDependencies(t, runner)
+	var events []string
+	deps.restoreFile = func(_ context.Context, _ config.Installation, entry ArchiveEntryMetadata, _ io.Reader) error {
+		events = append(events, "file:"+entry.Path)
+		return nil
+	}
+	deps.restoreVolume = func(_ context.Context, _ config.Installation, volume VolumeMetadata, stream io.Reader) error {
+		if _, err := io.ReadAll(stream); err != nil {
+			return err
+		}
+		events = append(events, "volume:"+volume.LogicalName)
+		return nil
+	}
+	deps.resetAuthenticationState = func(context.Context, config.Installation, archiveRunner) error {
+		events = append(events, "reset-auth-state")
+		return nil
+	}
+
+	if _, err := restoreWithDependencies(context.Background(), installation, RestoreRequest{Archive: archive, Confirm: true}, deps); err != nil {
+		t.Fatal(err)
+	}
+	if got, want := events, []string{
+		"file:configuration/operator.env",
+		"volume:sessions",
+		"volume:settings",
+		"reset-auth-state",
+	}; !equalStrings(got, want) {
+		t.Fatalf("restore events = %v, want %v", got, want)
+	}
+}
+
+func safeRestoreTar(t *testing.T, name, contents string) []byte {
+	t.Helper()
+	var output bytes.Buffer
+	writer := tar.NewWriter(&output)
+	if err := writer.WriteHeader(&tar.Header{Name: name, Mode: 0o600, Size: int64(len(contents)), Typeflag: tar.TypeReg}); err != nil {
+		t.Fatal(err)
+	}
+	if _, err := writer.Write([]byte(contents)); err != nil {
+		t.Fatal(err)
+	}
+	if err := writer.Close(); err != nil {
+		t.Fatal(err)
+	}
+	return output.Bytes()
+}
+
 func TestRestoreStoppedInstallationRunsCheckpointRestoreAndVerification(t *testing.T) {
 	installation := preflightTestInstallation(t)
 	archive := filepath.Join(t.TempDir(), "restore.zip")
@@ -103,7 +184,9 @@ func TestResetAuthenticationStateCreatesOnlyPrivateEmptyStateDirectories(t *test
 	joined := strings.Join(runner.args, "\x00")
 	for _, required := range []string{
 		"run", "--rm", "--no-deps", "--no-TTY", "--entrypoint", "sh", "core", "-ceu",
-		"rm -rf /data/auth && install -d -m 0700 /data/auth /data/auth/sessions /data/auth/oidc",
+		"find /data/auth -mindepth 1 -maxdepth 1 -exec rm -rf -- {} +",
+		"install -d -m 0700 /data/auth /data/auth/sessions /data/auth/oidc",
+		"find /data/auth/sessions /data/auth/oidc -mindepth 1 -print -quit",
 	} {
 		if !strings.Contains(joined, required) {
 			t.Fatalf("authentication state reset command omits %q: %#v", required, runner.args)