diff --git a/.env.example b/.env.example
index 34c478edfa..80ce97e535 100644
--- a/.env.example
+++ b/.env.example
@@ -130,6 +130,9 @@ GITTENSORY_REVIEW_DRAFT=false
 # DATABASE_PATH=/data/gittensory.sqlite     # SQLite file on the mounted data volume; all migrations auto-apply
 # DATABASE_URL=                              # set to postgres://user:pw@host:5432/db to use Postgres instead of
 #                                            #   SQLite (shared DB → multi-instance). Overrides DATABASE_PATH.
+# BACKUP_ACKNOWLEDGED=                       # set to "true" to silence the boot warning that a single SQLite file
+#                                            #   has no backup — only after you've wired Litestream (docs §6) or
+#                                            #   equivalent. Unset on SQLite ⇒ a loud data-loss warning at boot.
 # REDIS_URL=                                 # set to redis://host:6379 for distributed rate limiting + webhook dedup
 #                                            #   cache (prevents double-processing of GitHub retries). Off when unset.
 # QDRANT_URL=                                # set to http://qdrant:6333 to use Qdrant as the RAG vector store
diff --git a/docs/self-hosting.md b/docs/self-hosting.md
index 3334081fd4..5e67d983d7 100644
--- a/docs/self-hosting.md
+++ b/docs/self-hosting.md
@@ -238,11 +238,13 @@ accepted. Unset ⇒ the public file is fetched exactly as before.
   in-flight job, checkpoints the WAL, and closes the DB before exiting.
 - **Logs** are structured JSON (`selfhost_listening`, `selfhost_migrations_applied`, `selfhost_ai_provider`,
   `selfhost_queue_recovered`, `selfhost_job_dead`, `selfhost_cron_error`, `selfhost_shutdown`, …).
-- **Data + backup.** Everything is the single SQLite file on the `gittensory-data` volume (WAL mode). Back up
-  by snapshotting the volume or copying the `.sqlite` file. Migrations are idempotent and re-checked at boot.
-  For **continuous, point-in-time backup**, enable the optional [Litestream](https://litestream.io) sidecar in
+- **Data + backup (do NOT skip).** Everything is the single SQLite file on the `gittensory-data` volume (WAL
+  mode), so **without a backup, losing the volume loses all review state** — and `/ready` still answers `200`,
+  so the gap is silent. The container logs a loud `selfhost_backup_advisory` warning at boot until you set up a
+  backup. For **continuous, point-in-time backup**, enable the [Litestream](https://litestream.io) sidecar in
   `docker-compose.yml` (copy `litestream.yml.example` → `litestream.yml`, set your bucket + credentials); it
-  streams every change to S3/B2/MinIO/R2.
+  streams every change to S3/B2/MinIO/R2. Then set **`BACKUP_ACKNOWLEDGED=true`** to silence the warning. (For
+  multi-instance, use `DATABASE_URL=postgres://…` and back up Postgres instead.)
 - **App-level metrics.** Enable `GITTENSORY_REVIEW_OPS=true` for the read-only gate-block anomaly scan and the
   bearer-gated `GET /v1/internal/ops/stats` aggregate.
 
diff --git a/src/selfhost/health.ts b/src/selfhost/health.ts
index 4accc343a3..6f350391af 100644
--- a/src/selfhost/health.ts
+++ b/src/selfhost/health.ts
@@ -42,3 +42,12 @@ export async function readiness(db: D1Database, probes: ReadinessProbe[] = []):
   }
   return { ok: Object.values(checks).every(Boolean), checks };
 }
+
+/** Boot-time DATA-SAFETY advisory. A single SQLite file with no acknowledged backup is a data-loss SPOF — yet
+ *  `/ready` would still answer 200, so an operator can run with zero durability believing they're healthy. Returns
+ *  the warning to log at boot (or null on Postgres, or once the operator sets `BACKUP_ACKNOWLEDGED=true` after
+ *  wiring Litestream or another backup). */
+export function sqliteBackupAdvisory(opts: { usingSqlite: boolean; backupAcknowledged: boolean }): string | null {
+  if (!opts.usingSqlite || opts.backupAcknowledged) return null;
+  return "Running on a single SQLite file with no acknowledged backup — if the volume is lost, ALL review state is lost. Enable the Litestream sidecar (docs/self-hosting.md §6) to stream the WAL to S3/B2/MinIO, then set BACKUP_ACKNOWLEDGED=true to silence this warning. (Multi-instance: use DATABASE_URL=postgres://… instead.)";
+}
diff --git a/src/server.ts b/src/server.ts
index e0b1b687c2..82c41022c3 100644
--- a/src/server.ts
+++ b/src/server.ts
@@ -28,7 +28,7 @@ import {
 import { isOrbBrokerMode, registerOrbRelayTarget } from "./orb/broker-client";
 import { exportOrbBatch } from "./selfhost/orb-collector";
 import { createD1Adapter, nodeSqliteDriver } from "./selfhost/d1-adapter";
-import { readiness, type ReadinessProbe } from "./selfhost/health";
+import { readiness, sqliteBackupAdvisory, type ReadinessProbe } from "./selfhost/health";
 import { gauge, incr, observe, renderMetrics } from "./selfhost/metrics";
 import { runSelfHostMigrations } from "./selfhost/migrate";
 import { createPgAdapter } from "./selfhost/pg-adapter";
@@ -177,6 +177,10 @@ async function main(): Promise<void> {
   const usePostgres = !!databaseUrl && /^postgres(ql)?:\/\//i.test(databaseUrl);
   const backend = usePostgres ? await buildPostgresBackend(databaseUrl as string, consume) : buildSqliteBackend(consume);
   console.log(JSON.stringify({ event: "selfhost_backend", backend: usePostgres ? "postgres" : "sqlite" }));
+  // Data-safety advisory (#8): warn LOUDLY at boot if running on a single SQLite file with no acknowledged backup,
+  // so an operator doesn't run with zero durability while /ready answers 200.
+  const backupAdvisory = sqliteBackupAdvisory({ usingSqlite: !usePostgres, backupAcknowledged: process.env.BACKUP_ACKNOWLEDGED === "true" });
+  if (backupAdvisory) console.warn(JSON.stringify({ level: "warn", event: "selfhost_backup_advisory", message: backupAdvisory }));
 
   const applied = await runSelfHostMigrations(backend.db, process.env.MIGRATIONS_DIR ?? "migrations");
   console.log(JSON.stringify({ event: "selfhost_migrations_applied", count: applied }));
diff --git a/test/unit/selfhost-health.test.ts b/test/unit/selfhost-health.test.ts
index d9b3506b68..0c5c53132d 100644
--- a/test/unit/selfhost-health.test.ts
+++ b/test/unit/selfhost-health.test.ts
@@ -1,7 +1,15 @@
 import { DatabaseSync } from "node:sqlite";
 import { describe, expect, it } from "vitest";
 import { createD1Adapter, nodeSqliteDriver } from "../../src/selfhost/d1-adapter";
-import { readiness } from "../../src/selfhost/health";
+import { readiness, sqliteBackupAdvisory } from "../../src/selfhost/health";
+
+describe("sqliteBackupAdvisory (#8 data-safety)", () => {
+  it("warns on SQLite without an acknowledged backup, and is silent otherwise", () => {
+    expect(sqliteBackupAdvisory({ usingSqlite: true, backupAcknowledged: false })).toMatch(/single SQLite file with no acknowledged backup/);
+    expect(sqliteBackupAdvisory({ usingSqlite: true, backupAcknowledged: true })).toBeNull(); // operator acknowledged
+    expect(sqliteBackupAdvisory({ usingSqlite: false, backupAcknowledged: false })).toBeNull(); // Postgres
+  });
+});
 
 describe("readiness (#982)", () => {
   it("is not ready until the migrations table has applied rows", async () => {