diff --git a/docs/superpowers/plans/2026-07-20-postgres-quality-gate-foundation.md b/docs/superpowers/plans/2026-07-20-postgres-quality-gate-foundation.md
index d93c96a1..9da03f40 100644
--- a/docs/superpowers/plans/2026-07-20-postgres-quality-gate-foundation.md
+++ b/docs/superpowers/plans/2026-07-20-postgres-quality-gate-foundation.md
@@ -500,17 +500,11 @@ alter default privileges for role schema_owner in schema public
   revoke all on tables from public;
 alter default privileges for role schema_owner in schema audit
   revoke all on tables from public;
-alter default privileges for role schema_owner in schema identity
-  grant select, insert, update, delete on tables to identity_runtime;
-alter default privileges for role schema_owner in schema identity
-  grant select on tables to admin_runtime;
-alter default privileges for role schema_owner in schema public
-  grant select, insert, update, delete on tables to app_runtime, admin_runtime;
-alter default privileges for role schema_owner in schema audit
-  grant select, insert on tables to admin_runtime;
 ```
 
-Do not create business or auth tables.
+Do not create business or auth tables. The foundation grants schema discovery only;
+later reviewed migrations grant access to named tables and narrow functions. Never
+grant runtime roles broad default DML on future tables.
 
 - [ ] **Step 7: Put runner in final web image**
 
diff --git a/frontend/db/migrations/20260720000100_backend_foundation.sql b/frontend/db/migrations/20260720000100_backend_foundation.sql
index 85d67e42..ca47fee9 100644
--- a/frontend/db/migrations/20260720000100_backend_foundation.sql
+++ b/frontend/db/migrations/20260720000100_backend_foundation.sql
@@ -13,11 +13,3 @@ alter default privileges for role schema_owner in schema public
   revoke all on tables from public;
 alter default privileges for role schema_owner in schema audit
   revoke all on tables from public;
-alter default privileges for role schema_owner in schema identity
-  grant select, insert, update, delete on tables to identity_runtime;
-alter default privileges for role schema_owner in schema identity
-  grant select on tables to admin_runtime;
-alter default privileges for role schema_owner in schema public
-  grant select, insert, update, delete on tables to app_runtime, admin_runtime;
-alter default privileges for role schema_owner in schema audit
-  grant select, insert on tables to admin_runtime;
diff --git a/frontend/scripts/db-migrate.mjs b/frontend/scripts/db-migrate.mjs
index 217e6f8c..737b9a73 100644
--- a/frontend/scripts/db-migrate.mjs
+++ b/frontend/scripts/db-migrate.mjs
@@ -17,6 +17,18 @@ async function loadMigrationFiles(migrationsDirectory) {
     throw new SafeMigrationError("unable to read migrations directory");
   }
 
+  const malformedSqlEntry = entries.find(
+    (entry) =>
+      entry.isFile() &&
+      entry.name.endsWith(".sql") &&
+      !migrationFilenamePattern.test(entry.name),
+  );
+  if (malformedSqlEntry) {
+    throw new SafeMigrationError(
+      `invalid migration filename: ${malformedSqlEntry.name}`,
+    );
+  }
+
   return Promise.all(
     entries
       .filter(
diff --git a/frontend/tests/database-foundation.test.ts b/frontend/tests/database-foundation.test.ts
index bd32b0ad..dda1715d 100644
--- a/frontend/tests/database-foundation.test.ts
+++ b/frontend/tests/database-foundation.test.ts
@@ -20,6 +20,7 @@ const migrationFilename = "20260720000100_backend_foundation.sql";
 const pendingFilename = "20260720000200_pending_check.sql";
 const concurrentFilename = "20260720000300_concurrent_lock.sql";
 const failingFilename = "20260720000400_atomic_rollback.sql";
+const malformedFilename = "20260720_malformed.sql";
 const runnerPath = fileURLToPath(
   new URL("../scripts/db-migrate.mjs", import.meta.url),
 );
@@ -128,6 +129,17 @@ test("migration runner is serialized, atomic, drift-safe, and read-only in check
   try {
     copyFileSync(migrationPath, copiedMigration);
 
+    const malformedPath = join(temporaryDirectory, malformedFilename);
+    writeFileSync(malformedPath, "select 1;\n");
+    const malformedCheck = runMigration(schemaUrl, {
+      check: true,
+      migrationsDirectory: temporaryDirectory,
+    });
+    results.push(malformedCheck);
+    assert.equal(malformedCheck.status, 1);
+    assert.match(malformedCheck.stderr, /invalid migration filename/);
+    unlinkSync(malformedPath);
+
     const missingLedgerCheck = runMigration(schemaUrl, {
       check: true,
       migrationsDirectory: temporaryDirectory,
@@ -330,3 +342,91 @@ insert into atomic_rollback_probe.child (parent_id) values (1);
     rmSync(temporaryDirectory, { force: true, recursive: true });
   }
 });
+
+test("foundation grants no direct runtime table DML and exposes only reviewed functions", () => {
+  const fixture = startPostgresFixture();
+  const temporaryDirectory = mkdtempSync(join(tmpdir(), "jyotisha-privileges-"));
+  const schemaUrl = fixture.connectionUrl(
+    "schema_owner",
+    "schema-owner-test-password",
+  );
+
+  try {
+    copyFileSync(migrationPath, join(temporaryDirectory, migrationFilename));
+    const migration = runMigration(schemaUrl, {
+      migrationsDirectory: temporaryDirectory,
+    });
+    assert.equal(migration.status, 0, migration.stderr);
+
+    fixture.psqlAs(
+      "schema_owner",
+      "schema-owner-test-password",
+      `
+        create table public.runtime_boundary_probe (
+          id integer primary key,
+          value text not null
+        );
+        create table identity.runtime_boundary_probe (
+          id integer primary key,
+          value text not null
+        );
+        create table audit.admin_event_probe (
+          value text not null
+        );
+        create function audit.record_admin_event_probe(event_value text)
+        returns void
+        language sql
+        security definer
+        set search_path = pg_catalog, audit
+        as 'insert into audit.admin_event_probe(value) values (event_value)';
+        revoke all on function audit.record_admin_event_probe(text) from public;
+        grant execute on function audit.record_admin_event_probe(text) to admin_runtime;
+      `,
+    );
+
+    assert.throws(() =>
+      fixture.psqlAs(
+        "app_runtime",
+        "app-runtime-test-password",
+        "insert into public.runtime_boundary_probe values (1, 'denied')",
+      ),
+    );
+    assert.throws(() =>
+      fixture.psqlAs(
+        "admin_runtime",
+        "admin-runtime-test-password",
+        "insert into audit.admin_event_probe values ('denied')",
+      ),
+    );
+    assert.throws(() =>
+      fixture.psqlAs(
+        "identity_runtime",
+        "identity-runtime-test-password",
+        "insert into identity.runtime_boundary_probe values (1, 'denied')",
+      ),
+    );
+    assert.throws(() =>
+      fixture.psqlAs(
+        "admin_runtime",
+        "admin-runtime-test-password",
+        "update public.runtime_boundary_probe set value = 'denied'",
+      ),
+    );
+
+    assert.equal(
+      fixture.psqlAs(
+        "admin_runtime",
+        "admin-runtime-test-password",
+        "select audit.record_admin_event_probe('approved')",
+      ),
+      "",
+    );
+    assert.equal(
+      fixture.psql("select value from audit.admin_event_probe"),
+      "approved",
+    );
+  } finally {
+    fixture.stop();
+    rmSync(temporaryDirectory, { force: true, recursive: true });
+  }
+});
diff --git a/frontend/tests/helpers/postgres-fixture.ts b/frontend/tests/helpers/postgres-fixture.ts
index 5fb9aa0a..ebda7d75 100644
--- a/frontend/tests/helpers/postgres-fixture.ts
+++ b/frontend/tests/helpers/postgres-fixture.ts
@@ -15,6 +15,7 @@ export type PostgresFixture = {
   hostPort: number;
   connectionUrl(role: string, password: string): string;
   psql(sql: string): string;
+  psqlAs(role: string, password: string, sql: string): string;
   stop(): void;
 };
 
@@ -145,6 +146,29 @@ export function startPostgresFixture(): PostgresFixture {
         .trim()
         .replace(/(^|:)false(?=:|$)/gm, "$1f");
     },
+    psqlAs(role, password, sql) {
+      return execFileSync(
+        "docker",
+        [
+          ...composeArguments,
+          "exec",
+          "-T",
+          "-e",
+          `PGPASSWORD=${password}`,
+          "postgres",
+          "psql",
+          "-v",
+          "ON_ERROR_STOP=1",
+          "-U",
+          role,
+          "-d",
+          "jyotisha",
+          "-Atc",
+          sql,
+        ],
+        { encoding: "utf8", env: environment },
+      ).trim();
+    },
     stop() {
       try {
         execFileSync(