diff --git a/cmd/ate-setup/internal/config/config.go b/cmd/ate-setup/internal/config/config.go
index 5f13ac365..fc05546fe 100644
--- a/cmd/ate-setup/internal/config/config.go
+++ b/cmd/ate-setup/internal/config/config.go
@@ -49,6 +49,10 @@ const DefaultRolloutTimeout = 60 * time.Second
 // podidentity credential bundle.
 const DefaultPostgresConnectionString = "postgresql://postgres@postgres.ate-system.svc:5432/atepg?sslmode=verify-full&sslrootcert=/run/servicedns.podcert.ate.dev/trust-bundle.pem&sslcert=/run/podidentity.podcert.ate.dev/credential-bundle.pem&sslkey=/run/podidentity.podcert.ate.dev/credential-bundle.pem"
 
+// DefaultPostgresSchema mirrors the shell installer's default for
+// ATE_API_POSTGRES_SCHEMA, the PostgreSQL schema holding the Substrate tables.
+const DefaultPostgresSchema = "public"
+
 // devEnvFile is the optional per-developer environment script at the repo root.
 const devEnvFile = ".ate-dev-env.sh"
 
@@ -96,6 +100,9 @@ type Config struct {
 	// PostgresConnectionString is the apiserver's store connection string.
 	// Empty means use DefaultPostgresConnectionString.
 	PostgresConnectionString string
+	// PostgresSchema is the PostgreSQL schema for the Substrate tables
+	// (ATE_API_POSTGRES_SCHEMA). Empty means DefaultPostgresSchema.
+	PostgresSchema string
 
 	// RolloutTimeout is the timeout duration for rollout status checks.
 	RolloutTimeout time.Duration
@@ -214,6 +221,7 @@ func Load(opts Options) (*Config, error) {
 		KODefaultPlatforms:             env["KO_DEFAULTPLATFORMS"],
 		Images:                         loadImageSource(opts, env),
 		PostgresConnectionString:       env["ATE_API_POSTGRES_CONNECTION_STRING"],
+		PostgresSchema:                 env["ATE_API_POSTGRES_SCHEMA"],
 		RolloutTimeout:                 rolloutTimeout,
 		rolloutTimeoutSet:              timeoutStr != "",
 		PodcertWorkersPerSigner:        podcertWorkers,
@@ -312,6 +320,15 @@ func (c *Config) PostgresConnString() string {
 	return DefaultPostgresConnectionString
 }
 
+// PostgresSchemaName returns the configured schema, falling back to the
+// shell installer's default. ate-api-server rejects an empty value.
+func (c *Config) PostgresSchemaName() string {
+	if c.PostgresSchema != "" {
+		return c.PostgresSchema
+	}
+	return DefaultPostgresSchema
+}
+
 // WaitTimeout returns how long to wait for a workload whose historical timeout
 // was historical.
 //
diff --git a/cmd/ate-setup/internal/config/config_test.go b/cmd/ate-setup/internal/config/config_test.go
index 288fef34f..7173e1e19 100644
--- a/cmd/ate-setup/internal/config/config_test.go
+++ b/cmd/ate-setup/internal/config/config_test.go
@@ -41,6 +41,7 @@ func loadEnv(t *testing.T) {
 		"ANTHROPIC_API_KEY",
 		"ATE_ADDITIONAL_EGRESS_EXTPROC_SERVICE",
 		"ATE_API_POSTGRES_CONNECTION_STRING",
+		"ATE_API_POSTGRES_SCHEMA",
 		"ATE_ATENET_ROUTER",
 		"ATE_EXPERIMENTAL_USE_SDSMINT",
 		"ATE_IMAGE_REPO",
@@ -115,6 +116,28 @@ func TestLoadPostgresConnectionStringOverride(t *testing.T) {
 	}
 }
 
+// ATE_API_POSTGRES_SCHEMA defaults to public, as in the shell installer, and
+// an explicit value wins.
+func TestLoadPostgresSchema(t *testing.T) {
+	loadEnv(t)
+	cfg, err := Load(Options{})
+	if err != nil {
+		t.Fatalf("Load() error = %v", err)
+	}
+	if cfg.PostgresSchemaName() != DefaultPostgresSchema {
+		t.Errorf("PostgresSchemaName() = %q, want %q", cfg.PostgresSchemaName(), DefaultPostgresSchema)
+	}
+
+	t.Setenv("ATE_API_POSTGRES_SCHEMA", "substrate")
+	cfg, err = Load(Options{})
+	if err != nil {
+		t.Fatalf("Load() error = %v", err)
+	}
+	if cfg.PostgresSchemaName() != "substrate" {
+		t.Errorf("PostgresSchemaName() = %q, want %q", cfg.PostgresSchemaName(), "substrate")
+	}
+}
+
 // ate-setup's own client resolves $KUBECONFIG through the client-go loading
 // rules, so the value has to reach ScriptEnv as well. Otherwise a developer who
 // exports KUBECONFIG without passing --kubeconfig gets an install split across
diff --git a/cmd/ate-setup/internal/steps/create.go b/cmd/ate-setup/internal/steps/create.go
index 9add90796..b43a0f506 100644
--- a/cmd/ate-setup/internal/steps/create.go
+++ b/cmd/ate-setup/internal/steps/create.go
@@ -121,7 +121,8 @@ func (e *Env) CreateActorIDCACertsSecret(ctx context.Context) error {
 
 // CreateAPIServerEnvVars writes the ConfigMap that tells ate-api-server how to
 // reach its PostgreSQL store. ate-api-server.yaml pulls it in via an optional
-// envFrom and resolves --postgres-connection-string=@env from it.
+// envFrom and resolves --postgres-connection-string=@env and
+// --postgres-schema=@env from it.
 func (e *Env) CreateAPIServerEnvVars(ctx context.Context) error {
 	log.Step("create_api_server_env_vars")
 	if err := e.Kube.EnsureNamespace(ctx, NamespaceAteSystem); err != nil {
@@ -131,16 +132,19 @@ func (e *Env) CreateAPIServerEnvVars(ctx context.Context) error {
 	connString := e.Cfg.PostgresConnString()
 	log.Infof("POSTGRES_CONNECTION_STRING: %s", connString)
 
-	return e.Kube.ApplyConfigMap(ctx, NamespaceAteSystem, ConfigMapAPIEnvVars, buildAPIServerEnvVars(connString))
+	return e.Kube.ApplyConfigMap(ctx, NamespaceAteSystem, ConfigMapAPIEnvVars,
+		buildAPIServerEnvVars(connString, e.Cfg.PostgresSchemaName()))
 }
 
-// buildAPIServerEnvVars is the ConfigMap payload. ate-api-server takes only the
-// connection string from it; an unrecognized key here reaches the container as
-// a stray environment variable, so the set stays exactly what the shell
-// installer's create_api_server_env_vars wrote.
-func buildAPIServerEnvVars(connString string) map[string]string {
+// buildAPIServerEnvVars is the ConfigMap payload. ate-api-server takes the
+// connection string and the schema from it, and exits on an empty schema; an
+// unrecognized key here reaches the container as a stray environment variable,
+// so the set stays exactly what the shell installer's
+// create_api_server_env_vars writes.
+func buildAPIServerEnvVars(connString, schema string) map[string]string {
 	return map[string]string{
 		"ATE_API_POSTGRES_CONNECTION_STRING": connString,
+		"ATE_API_POSTGRES_SCHEMA":            schema,
 	}
 }
 
diff --git a/cmd/ate-setup/internal/steps/create_test.go b/cmd/ate-setup/internal/steps/create_test.go
index 3998cb31a..e21200483 100644
--- a/cmd/ate-setup/internal/steps/create_test.go
+++ b/cmd/ate-setup/internal/steps/create_test.go
@@ -23,22 +23,26 @@ import (
 	"github.com/agent-substrate/substrate/internal/localca"
 )
 
-// ate-api-server resolves --postgres-connection-string=@env from this
-// ConfigMap. It is the only key the shell installer wrote, and an empty value
-// makes the apiserver exit with "--postgres-connection-string is required", so
-// both the key set and the value are pinned here.
+// ate-api-server resolves --postgres-connection-string=@env and
+// --postgres-schema=@env from this ConfigMap. These are the keys the shell
+// installer writes, and an empty value for either makes the apiserver exit
+// ("--postgres-connection-string is required", "PostgreSQL schema must not be
+// empty"), so both the key set and the values are pinned here.
 func TestBuildAPIServerEnvVars(t *testing.T) {
 	const dsn = "postgresql://postgres@postgres.ate-system.svc:5432/atepg?sslmode=verify-full"
 
-	got := buildAPIServerEnvVars(dsn)
+	got := buildAPIServerEnvVars(dsn, "public")
 
-	want := []string{"ATE_API_POSTGRES_CONNECTION_STRING"}
+	want := []string{"ATE_API_POSTGRES_CONNECTION_STRING", "ATE_API_POSTGRES_SCHEMA"}
 	if keys := slices.Sorted(maps.Keys(got)); !slices.Equal(keys, want) {
 		t.Errorf("keys = %v, want %v", keys, want)
 	}
 	if got["ATE_API_POSTGRES_CONNECTION_STRING"] != dsn {
 		t.Errorf("ATE_API_POSTGRES_CONNECTION_STRING = %q, want %q", got["ATE_API_POSTGRES_CONNECTION_STRING"], dsn)
 	}
+	if got["ATE_API_POSTGRES_SCHEMA"] != "public" {
+		t.Errorf("ATE_API_POSTGRES_SCHEMA = %q, want %q", got["ATE_API_POSTGRES_SCHEMA"], "public")
+	}
 }
 
 // The expected strings here are what the shell installer's