Change to only store a prefix of the datastore's unique ID in the zed…

…token

Results in smaller tokens but given that datastore IDs are generated, should still minimize the chances of a conflict

internal/services/v1/debug_test.go

@@ -906,7 +906,7 @@ func TestBulkCheckPermissionWithDebug(t *testing.T) {
 			checkResp, err := client.CheckBulkPermissions(ctx, &v1.CheckBulkPermissionsRequest{
 				Consistency: &v1.Consistency{
 					Requirement: &v1.Consistency_AtLeastAsFresh{
-						AtLeastAsFresh: zedtoken.MustNewFromRevision(revision),
+						AtLeastAsFresh: zedtoken.MustNewFromRevisionForTesting(revision),
 					},
 				},
 				WithTracing: true,

internal/services/v1/watch.go

@@ -56,8 +56,13 @@ func (ws *watchServer) Watch(req *v1.WatchRequest, stream v1.WatchService_WatchS
 			return status.Errorf(codes.InvalidArgument, "failed to decode start revision: %s", err)
 		}
 
+		// NOTE: if the token given is for a different datastore, we return an error and immediately fail the watch.
+		// This is necessary because asking for a resumed watch on a *different* datastore instance makes little semantic
+		// sense and, if we allowed it here, would likely result in missing or wrong events being emitted. This is the
+		// safest option and should only cause an issue if a client is connecting between instances of SpiceDBs which are,
+		// themselves, connecting to different datastore instances, which should itself be an invalid configuration.
 		if tokenStatus == zedtoken.StatusMismatchedDatastoreID {
-			return status.Errorf(codes.InvalidArgument, "start revision was generated by a different datastore")
+			return status.Errorf(codes.InvalidArgument, "start revision was generated by a different datastore instance")
 		}
 
 		afterRevision = decodedRevision

pkg/middleware/consistency/consistency_test.go

@@ -220,7 +220,7 @@ func TestAtExactSnapshotWithMismatchedToken(t *testing.T) {
 	updated := ContextWithHandle(context.Background())
 	updated = datastoremw.ContextWithDatastore(updated, ds)
 
-	// mint a token with a different datastore ID.
+	// mint a token with a different datastore instance ID.
 	ds.CurrentUniqueID = "foo"
 	zedToken, err := zedtoken.NewFromRevision(context.Background(), optimized, ds)
 	require.NoError(err)
@@ -234,7 +234,7 @@ func TestAtExactSnapshotWithMismatchedToken(t *testing.T) {
 		},
 	}, ds, "somelabel", TreatMismatchingTokensAsError)
 	require.Error(err)
-	require.ErrorContains(err, "ZedToken specified references an older datastore but at-exact-snapshot")
+	require.ErrorContains(err, "ZedToken specified references a different datastore instance but at-exact-snapshot")
 }
 
 func TestAtLeastAsFreshWithMismatchedTokenExpectError(t *testing.T) {
@@ -248,7 +248,7 @@ func TestAtLeastAsFreshWithMismatchedTokenExpectError(t *testing.T) {
 	updated := ContextWithHandle(context.Background())
 	updated = datastoremw.ContextWithDatastore(updated, ds)
 
-	// mint a token with a different datastore ID.
+	// mint a token with a different datastore instance ID.
 	ds.CurrentUniqueID = "foo"
 	zedToken, err := zedtoken.NewFromRevision(context.Background(), optimized, ds)
 	require.NoError(err)
@@ -262,7 +262,7 @@ func TestAtLeastAsFreshWithMismatchedTokenExpectError(t *testing.T) {
 		},
 	}, ds, "somelabel", TreatMismatchingTokensAsError)
 	require.Error(err)
-	require.ErrorContains(err, "ZedToken specified references an older datastore and SpiceDB is configured to raise an error in this scenario")
+	require.ErrorContains(err, "ZedToken specified references a different datastore instance and SpiceDB is configured to raise an error in this scenario")
 }
 
 func TestAtLeastAsFreshWithMismatchedTokenExpectMinLatency(t *testing.T) {
@@ -276,7 +276,7 @@ func TestAtLeastAsFreshWithMismatchedTokenExpectMinLatency(t *testing.T) {
 	updated := ContextWithHandle(context.Background())
 	updated = datastoremw.ContextWithDatastore(updated, ds)
 
-	// mint a token with a different datastore ID.
+	// mint a token with a different datastore instance ID.
 	ds.CurrentUniqueID = "foo"
 	zedToken, err := zedtoken.NewFromRevision(context.Background(), optimized, ds)
 	require.NoError(err)
@@ -310,7 +310,7 @@ func TestAtLeastAsFreshWithMismatchedTokenExpectFullConsistency(t *testing.T) {
 	updated := ContextWithHandle(context.Background())
 	updated = datastoremw.ContextWithDatastore(updated, ds)
 
-	// mint a token with a different datastore ID.
+	// mint a token with a different datastore instance ID.
 	ds.CurrentUniqueID = "foo"
 	zedToken, err := zedtoken.NewFromRevision(context.Background(), optimized, ds)
 	require.NoError(err)