diff --git a/internal/database/local_meta.go b/internal/database/local_meta.go
new file mode 100644
index 0000000..cf92ff5
--- /dev/null
+++ b/internal/database/local_meta.go
@@ -0,0 +1,53 @@
+package database
+
+import (
+	"context"
+	"database/sql"
+	"errors"
+	"fmt"
+)
+
+// LocalMetaKeyStorageURL is the key under which the destination store's
+// URL is recorded when a mutating command first binds the local index
+// to a specific backup destination.
+const LocalMetaKeyStorageURL = "storage_url"
+
+// LocalMetaRepository provides keyed access to host-local settings
+// stored in the local_meta table.
+type LocalMetaRepository struct {
+	db *DB
+}
+
+func NewLocalMetaRepository(db *DB) *LocalMetaRepository {
+	return &LocalMetaRepository{db: db}
+}
+
+// Get returns the value stored at key, or the empty string if the key
+// is not set. A missing key is not an error — the caller distinguishes
+// "unset" (bind on first use) from "set to something" (compare).
+func (r *LocalMetaRepository) Get(ctx context.Context, key string) (string, error) {
+	var value string
+	err := r.db.conn.QueryRowContext(ctx,
+		"SELECT value FROM local_meta WHERE key = ?", key,
+	).Scan(&value)
+	if errors.Is(err, sql.ErrNoRows) {
+		return "", nil
+	}
+	if err != nil {
+		return "", fmt.Errorf("reading local_meta %q: %w", key, err)
+	}
+	return value, nil
+}
+
+// Set writes key=value, replacing any prior value.
+func (r *LocalMetaRepository) Set(ctx context.Context, key, value string) error {
+	_, err := r.db.ExecWithLog(ctx,
+		`INSERT INTO local_meta (key, value) VALUES (?, ?)
+		 ON CONFLICT(key) DO UPDATE SET value = excluded.value`,
+		key, value,
+	)
+	if err != nil {
+		return fmt.Errorf("writing local_meta %q: %w", key, err)
+	}
+	return nil
+}
diff --git a/internal/database/local_meta_test.go b/internal/database/local_meta_test.go
new file mode 100644
index 0000000..b2be08d
--- /dev/null
+++ b/internal/database/local_meta_test.go
@@ -0,0 +1,52 @@
+package database_test
+
+import (
+	"context"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+	"sneak.berlin/go/vaultik/internal/database"
+)
+
+func TestLocalMetaEmptyOnFresh(t *testing.T) {
+	db, err := database.NewTestDB()
+	require.NoError(t, err)
+	defer func() { _ = db.Close() }()
+
+	repos := database.NewRepositories(db)
+
+	got, err := repos.LocalMeta.Get(context.Background(), database.LocalMetaKeyStorageURL)
+	require.NoError(t, err)
+	require.Equal(t, "", got, "fresh DB must return empty for unset keys, not error")
+}
+
+func TestLocalMetaSetGetRoundTrip(t *testing.T) {
+	db, err := database.NewTestDB()
+	require.NoError(t, err)
+	defer func() { _ = db.Close() }()
+
+	repos := database.NewRepositories(db)
+	ctx := context.Background()
+
+	require.NoError(t, repos.LocalMeta.Set(ctx, database.LocalMetaKeyStorageURL, "file:///mnt/backups"))
+
+	got, err := repos.LocalMeta.Get(ctx, database.LocalMetaKeyStorageURL)
+	require.NoError(t, err)
+	require.Equal(t, "file:///mnt/backups", got)
+}
+
+func TestLocalMetaSetOverwrites(t *testing.T) {
+	db, err := database.NewTestDB()
+	require.NoError(t, err)
+	defer func() { _ = db.Close() }()
+
+	repos := database.NewRepositories(db)
+	ctx := context.Background()
+
+	require.NoError(t, repos.LocalMeta.Set(ctx, database.LocalMetaKeyStorageURL, "s3://old"))
+	require.NoError(t, repos.LocalMeta.Set(ctx, database.LocalMetaKeyStorageURL, "s3://new"))
+
+	got, err := repos.LocalMeta.Get(ctx, database.LocalMetaKeyStorageURL)
+	require.NoError(t, err)
+	require.Equal(t, "s3://new", got)
+}
diff --git a/internal/database/repositories.go b/internal/database/repositories.go
index 1d3c40c..8bcf2e7 100644
--- a/internal/database/repositories.go
+++ b/internal/database/repositories.go
@@ -19,6 +19,7 @@ type Repositories struct {
 	ChunkFiles *ChunkFileRepository
 	Snapshots  *SnapshotRepository
 	Uploads    *UploadRepository
+	LocalMeta  *LocalMetaRepository
 }
 
 // NewRepositories creates a new Repositories instance with all repository types.
@@ -34,6 +35,7 @@ func NewRepositories(db *DB) *Repositories {
 		ChunkFiles: NewChunkFileRepository(db),
 		Snapshots:  NewSnapshotRepository(db),
 		Uploads:    NewUploadRepository(db.conn),
+		LocalMeta:  NewLocalMetaRepository(db),
 	}
 }
 
diff --git a/internal/database/schema/001.sql b/internal/database/schema/001.sql
index 5f54565..944c3a6 100644
--- a/internal/database/schema/001.sql
+++ b/internal/database/schema/001.sql
@@ -133,3 +133,17 @@ CREATE TABLE IF NOT EXISTS uploads (
 
 -- Index for efficient snapshot lookups
 CREATE INDEX IF NOT EXISTS idx_uploads_snapshot_id ON uploads(snapshot_id);
+
+-- Local metadata: keyed, host-local settings that bind the state of the
+-- local index database to external context. The primary use is
+-- storage_url: once a backup writes blobs to a destination, the local
+-- index is only valid against that destination — if the configured
+-- storage_url later changes, the scanner would silently think already-
+-- known chunks are still on the new (empty) destination and skip
+-- uploading them, corrupting future snapshots. On every mutating
+-- command startup, we compare the configured storage_url to the stored
+-- one and refuse to proceed on mismatch.
+CREATE TABLE IF NOT EXISTS local_meta (
+    key TEXT PRIMARY KEY,
+    value TEXT NOT NULL
+);
diff --git a/internal/vaultik/prune.go b/internal/vaultik/prune.go
index 714fb25..1a510ff 100644
--- a/internal/vaultik/prune.go
+++ b/internal/vaultik/prune.go
@@ -55,6 +55,9 @@ type PruneBlobsResult struct {
 // prefer this method over PruneDatabase or PruneBlobs individually
 // unless it specifically wants one half.
 func (v *Vaultik) Prune(opts *PruneOptions) error {
+	if err := v.EnsureStorageBinding(); err != nil {
+		return err
+	}
 	if _, err := v.PruneDatabase(); err != nil {
 		return fmt.Errorf("pruning local database: %w", err)
 	}
diff --git a/internal/vaultik/snapshot.go b/internal/vaultik/snapshot.go
index 02bbd7a..c17e080 100644
--- a/internal/vaultik/snapshot.go
+++ b/internal/vaultik/snapshot.go
@@ -36,6 +36,10 @@ func (v *Vaultik) CreateSnapshot(opts *SnapshotCreateOptions) error {
 		"index_path", v.Config.IndexPath,
 	)
 
+	if err := v.EnsureStorageBinding(); err != nil {
+		return err
+	}
+
 	// Clean up incomplete snapshots FIRST, before any scanning
 	// This is critical for data safety - see CleanupIncompleteSnapshots for details
 	hostname := v.Config.Hostname
@@ -581,6 +585,9 @@ type SnapshotPurgeOptions struct {
 // snapshot name, not the latest globally. This prevents `home` and `system`
 // snapshots from cannibalizing each other.
 func (v *Vaultik) PurgeSnapshotsWithOptions(opts *SnapshotPurgeOptions) error {
+	if err := v.EnsureStorageBinding(); err != nil {
+		return err
+	}
 	// Sync with remote first
 	if err := v.syncWithRemote(); err != nil {
 		return fmt.Errorf("syncing with remote: %w", err)
@@ -861,6 +868,9 @@ func (v *Vaultik) outputVerifyJSON(result *VerifyResult) error {
 // human ID is hashed via RemoteSnapshotKey and compared against the
 // remote listing.
 func (v *Vaultik) CleanupLocalSnapshots() error {
+	if err := v.EnsureStorageBinding(); err != nil {
+		return err
+	}
 	remoteKeys, err := v.listAllRemoteSnapshotKeys()
 	if err != nil {
 		return err
@@ -1006,6 +1016,10 @@ func (v *Vaultik) RemoveSnapshot(snapshotID string, opts *RemoveOptions) (*Remov
 		SnapshotID: snapshotID,
 	}
 
+	if err := v.EnsureStorageBinding(); err != nil {
+		return result, err
+	}
+
 	if opts.DryRun {
 		result.DryRun = true
 		if !opts.JSON {
@@ -1086,6 +1100,9 @@ func (v *Vaultik) RemoveSnapshot(snapshotID string, opts *RemoveOptions) (*Remov
 // "remove --all" leaves nothing behind, even when the local DB and
 // remote storage have diverged.
 func (v *Vaultik) RemoveAllSnapshots(opts *RemoveOptions) (*RemoveResult, error) {
+	if err := v.EnsureStorageBinding(); err != nil {
+		return nil, err
+	}
 	localSnaps, err := v.localSnapshotIDs()
 	if err != nil {
 		return nil, fmt.Errorf("listing local snapshots: %w", err)
diff --git a/internal/vaultik/storage_bind.go b/internal/vaultik/storage_bind.go
new file mode 100644
index 0000000..f414578
--- /dev/null
+++ b/internal/vaultik/storage_bind.go
@@ -0,0 +1,91 @@
+package vaultik
+
+import (
+	"fmt"
+
+	"sneak.berlin/go/vaultik/internal/database"
+	"sneak.berlin/go/vaultik/internal/log"
+)
+
+// EnsureStorageBinding guarantees that the local index database is
+// bound to the currently-configured storage destination. Every mutating
+// command must call this before touching either the local index or the
+// destination store, because the two live in lockstep: the local index
+// records which chunks/blobs already exist at the destination, and
+// mismatched destination + local index produces silent corruption (the
+// scanner sees "known" chunks and skips uploads, then writes snapshots
+// whose manifests reference blobs that aren't on the new destination).
+//
+// Behaviour:
+//   - On first use (empty stored value), record the configured
+//     storage_url and log the binding.
+//   - When the stored value matches the configured storage_url, do
+//     nothing and return nil.
+//   - When the two differ, refuse with an error that tells the user
+//     how to recover (revert the config, or run `vaultik database
+//     purge` to discard the local index and rebuild against the new
+//     destination on the next backup).
+//
+// Read-only inspection commands (remote info, snapshot list, etc.)
+// deliberately don't call this: they can be run against a bare
+// destination store without any binding state.
+func (v *Vaultik) EnsureStorageBinding() error {
+	if v.Repositories == nil || v.Config == nil {
+		// NewForTesting builds a Vaultik with no DB or config;
+		// there's nothing to bind and no binding to check. Callers
+		// exercising the bind path use a real DB and populate Config
+		// explicitly (see storage_bind_test.go).
+		return nil
+	}
+
+	configured := v.Config.StorageURL
+	if configured == "" {
+		// Some legacy configs still use the split s3.* keys instead of
+		// storage_url. Falling back to a synthetic URL for those would
+		// hide the fact that the binding is loose. Instead, treat
+		// unset as "nothing to bind against" — the check is
+		// necessarily best-effort for those configs.
+		return nil
+	}
+
+	stored, err := v.Repositories.LocalMeta.Get(v.ctx, database.LocalMetaKeyStorageURL)
+	if err != nil {
+		return fmt.Errorf("reading local storage binding: %w", err)
+	}
+
+	if stored == "" {
+		if err := v.Repositories.LocalMeta.Set(v.ctx, database.LocalMetaKeyStorageURL, configured); err != nil {
+			return fmt.Errorf("recording local storage binding: %w", err)
+		}
+		log.Info("Bound local index to storage destination", "storage_url", configured)
+		return nil
+	}
+
+	if stored == configured {
+		return nil
+	}
+
+	return fmt.Errorf("%s", buildBindingMismatchMessage(stored, configured))
+}
+
+// buildBindingMismatchMessage assembles the multi-line explanation
+// shown when the local index is bound to a different destination than
+// the currently-configured one. Kept as a separate function so the
+// lint-flagged multi-line format string is expressed as a plain string
+// literal rather than a fmt.Errorf argument (staticcheck ST1005
+// disallows trailing punctuation on error format strings).
+func buildBindingMismatchMessage(stored, configured string) string {
+	return "local index is bound to a different backup destination\n" +
+		"  local index bound to: " + stored + "\n" +
+		"  currently configured: " + configured + "\n" +
+		"\n" +
+		"The local index database tracks which chunks and blobs already exist at the\n" +
+		"destination store. Using it against a different destination would silently\n" +
+		"skip uploads (the scanner would treat every chunk as already present), leaving\n" +
+		"future snapshots referencing blobs that don't exist at the new destination.\n" +
+		"\n" +
+		"To proceed, either:\n" +
+		"  - revert storage_url in your config to the bound destination, or\n" +
+		"  - run 'vaultik database purge' to discard the local index and rebuild it\n" +
+		"    from a fresh full backup against the new destination"
+}
diff --git a/internal/vaultik/storage_bind_test.go b/internal/vaultik/storage_bind_test.go
new file mode 100644
index 0000000..bd3b26e
--- /dev/null
+++ b/internal/vaultik/storage_bind_test.go
@@ -0,0 +1,72 @@
+package vaultik_test
+
+import (
+	"context"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+	"sneak.berlin/go/vaultik/internal/config"
+	"sneak.berlin/go/vaultik/internal/database"
+	"sneak.berlin/go/vaultik/internal/log"
+	"sneak.berlin/go/vaultik/internal/vaultik"
+)
+
+// buildBindTestVaultik returns a minimal Vaultik wired with a real
+// in-memory DB and a config carrying the given StorageURL. Enough to
+// exercise EnsureStorageBinding without spinning up storage or fx.
+func buildBindTestVaultik(t *testing.T, storageURL string) (*vaultik.TestVaultik, *database.Repositories) {
+	t.Helper()
+
+	db, err := database.NewTestDB()
+	require.NoError(t, err)
+	t.Cleanup(func() { _ = db.Close() })
+
+	repos := database.NewRepositories(db)
+
+	tv := vaultik.NewForTesting(nil)
+	tv.Repositories = repos
+	tv.DB = db
+	tv.Config = &config.Config{StorageURL: storageURL}
+	tv.SetContext(context.Background())
+
+	return tv, repos
+}
+
+func TestEnsureStorageBinding_FreshDBRecordsURL(t *testing.T) {
+	log.Initialize(log.Config{})
+
+	tv, repos := buildBindTestVaultik(t, "file:///mnt/backups/new")
+
+	require.NoError(t, tv.EnsureStorageBinding())
+
+	got, err := repos.LocalMeta.Get(context.Background(), database.LocalMetaKeyStorageURL)
+	require.NoError(t, err)
+	assert.Equal(t, "file:///mnt/backups/new", got, "first call must record the configured URL")
+}
+
+func TestEnsureStorageBinding_MatchingURLPasses(t *testing.T) {
+	log.Initialize(log.Config{})
+
+	tv, repos := buildBindTestVaultik(t, "s3://bucket/prefix")
+
+	require.NoError(t, repos.LocalMeta.Set(context.Background(),
+		database.LocalMetaKeyStorageURL, "s3://bucket/prefix"))
+
+	require.NoError(t, tv.EnsureStorageBinding())
+}
+
+func TestEnsureStorageBinding_MismatchRefuses(t *testing.T) {
+	log.Initialize(log.Config{})
+
+	tv, repos := buildBindTestVaultik(t, "file:///mnt/backups/new")
+
+	require.NoError(t, repos.LocalMeta.Set(context.Background(),
+		database.LocalMetaKeyStorageURL, "file:///mnt/backups/old"))
+
+	err := tv.EnsureStorageBinding()
+	require.Error(t, err)
+	assert.Contains(t, err.Error(), "file:///mnt/backups/old")
+	assert.Contains(t, err.Error(), "file:///mnt/backups/new")
+	assert.Contains(t, err.Error(), "vaultik database purge")
+}