diff --git a/packages/transform/__tests__/bundle-driver.test.ts b/packages/transform/__tests__/bundle-driver.test.ts
new file mode 100644
index 00000000..55b00936
--- /dev/null
+++ b/packages/transform/__tests__/bundle-driver.test.ts
@@ -0,0 +1,142 @@
+import { loadModule } from 'plpgsql-parser';
+
+import { makeNamespaceValidator, makeSchemaTranspiler } from '../src';
+
+beforeAll(async () => {
+  await loadModule();
+});
+
+const CTX = { change: 'schemas/auth/tables/users', kind: 'deploy' as const };
+
+describe('makeSchemaTranspiler', () => {
+  const transpiler = () =>
+    makeSchemaTranspiler({ schemaMap: { auth: 'tenant_auth', billing: 'tenant_billing' } });
+
+  describe('renameChange', () => {
+    it('renames the segment following a schemas segment', () => {
+      const { renameChange } = transpiler();
+      expect(renameChange('schemas/auth/tables/users')).toBe('schemas/tenant_auth/tables/users');
+      expect(renameChange('schemas/billing/procedures/charge')).toBe(
+        'schemas/tenant_billing/procedures/charge'
+      );
+    });
+
+    it('leaves unmapped schemas and non-schema segments untouched', () => {
+      const { renameChange } = transpiler();
+      expect(renameChange('schemas/public/tables/logs')).toBe('schemas/public/tables/logs');
+      expect(renameChange('roles/auth')).toBe('roles/auth');
+      expect(renameChange('extensions/auth/setup')).toBe('extensions/auth/setup');
+    });
+
+    it('does not rename a table segment that matches a schema name', () => {
+      const { renameChange } = transpiler();
+      expect(renameChange('schemas/public/tables/auth')).toBe('schemas/public/tables/auth');
+    });
+  });
+
+  describe('transformScript', () => {
+    it('rewrites schema references via the AST, not text', () => {
+      const t = transpiler();
+      const sql = [
+        '-- Deploy myapp:schemas/auth/tables/users to pg',
+        '',
+        'CREATE TABLE auth.users (',
+        '  id uuid PRIMARY KEY,',
+        '  auth text,',
+        "  note text DEFAULT 'auth'",
+        ');'
+      ].join('\n');
+      const out = t.transformScript(sql, CTX);
+      expect(out).toContain('tenant_auth.users');
+      // column named auth and string literal 'auth' are untouched
+      expect(out).toMatch(/\bauth text\b/);
+      expect(out).toContain("'auth'");
+      expect(t.result.schemasTransformed.get('auth')).toBe('tenant_auth');
+    });
+
+    it('rewrites FK targets, grants, policies and function bodies', () => {
+      const t = transpiler();
+      const sql = [
+        'CREATE TABLE billing.invoices (',
+        '  id uuid PRIMARY KEY,',
+        '  user_id uuid REFERENCES auth.users (id)',
+        ');',
+        'GRANT SELECT ON ALL TABLES IN SCHEMA billing TO authenticated;',
+        'CREATE POLICY p ON billing.invoices USING (user_id = auth.current_user_id());',
+        'CREATE FUNCTION billing.total()',
+        'RETURNS bigint',
+        'LANGUAGE plpgsql',
+        'AS $$',
+        'BEGIN',
+        '  RETURN (SELECT count(*) FROM billing.invoices JOIN auth.users u ON u.id = user_id);',
+        'END;',
+        '$$;'
+      ].join('\n');
+      const out = t.transformScript(sql, CTX);
+      expect(out).toContain('tenant_billing.invoices');
+      expect(out).toContain('tenant_auth.users');
+      expect(out).toContain('IN SCHEMA tenant_billing');
+      expect(out).toContain('tenant_auth.current_user_id()');
+      expect(out).not.toMatch(/\bbilling\./);
+      expect(out).not.toMatch(/\bauth\./);
+    });
+
+    it('accumulates a report across scripts', () => {
+      const t = transpiler();
+      t.transformScript('CREATE TABLE auth.a (id int);', CTX);
+      t.transformScript('CREATE TABLE billing.b (id int);', {
+        change: 'schemas/billing/tables/b',
+        kind: 'deploy'
+      });
+      expect([...t.result.schemasFound].sort()).toEqual(['auth', 'billing']);
+      expect(t.result.errors).toEqual([]);
+    });
+  });
+});
+
+describe('makeNamespaceValidator', () => {
+  it('reports creates/references/FK targets outside the allowed namespace', () => {
+    const validate = makeNamespaceValidator({ allowedSchemas: ['tenant_auth', 'public'] });
+    const violations = validate(
+      [
+        'CREATE TABLE tenant_auth.users (id uuid PRIMARY KEY);',
+        'CREATE TABLE tenant_auth.sessions (',
+        '  id uuid PRIMARY KEY,',
+        '  user_id uuid REFERENCES other_app.users (id)',
+        ');',
+        'SELECT * FROM billing.invoices;'
+      ].join('\n'),
+      CTX
+    );
+    expect(violations.some(v => v.includes('other_app.users'))).toBe(true);
+    expect(violations.some(v => v.includes('billing.invoices'))).toBe(true);
+    expect(violations.some(v => v.includes('tenant_auth'))).toBe(false);
+  });
+
+  it('returns no violations when everything is contained', () => {
+    const validate = makeNamespaceValidator({ allowedSchemas: ['tenant_auth'] });
+    expect(
+      validate('CREATE TABLE tenant_auth.users (id uuid PRIMARY KEY);', CTX)
+    ).toEqual([]);
+  });
+
+  it('optionally flags dynamic SQL', () => {
+    const sql = [
+      'CREATE FUNCTION tenant_auth.run(q text)',
+      'RETURNS void',
+      'LANGUAGE plpgsql',
+      'AS $$',
+      'BEGIN',
+      '  EXECUTE q;',
+      'END;',
+      '$$;'
+    ].join('\n');
+    const lax = makeNamespaceValidator({ allowedSchemas: ['tenant_auth'] });
+    expect(lax(sql, CTX)).toEqual([]);
+    const strict = makeNamespaceValidator({
+      allowedSchemas: ['tenant_auth'],
+      flagDynamicSql: true
+    });
+    expect(strict(sql, CTX).some(v => v.includes('dynamic SQL'))).toBe(true);
+  });
+});
diff --git a/packages/transform/src/bundle-driver.ts b/packages/transform/src/bundle-driver.ts
new file mode 100644
index 00000000..dbbb5056
--- /dev/null
+++ b/packages/transform/src/bundle-driver.ts
@@ -0,0 +1,113 @@
+/**
+ * Bundle transpile/apply drivers.
+ *
+ * Adapters that plug this package's AST transforms into the pgpm migration
+ * bundle seams (`transpileBundle`'s `renameChange`/`transformScript` and
+ * `applyBundle`'s `validateReferences`). The seams are structurally typed on
+ * purpose — no dependency on `@pgpmjs/bundle`/`@pgpmjs/core` — so the driver
+ * stays a pure function factory over `transformSql` and `classifyStatements`.
+ */
+
+import { classifyStatements } from './facts';
+import { SchemaTransformResult, transformSql, TransformSqlOptions } from './transform';
+
+/** Identity of the script being transformed/validated (matches the bundle seams). */
+export interface BundleScriptContext {
+  change: string;
+  kind: 'deploy' | 'revert' | 'verify';
+}
+
+export interface SchemaTranspilerOptions {
+  /** Old schema name → new schema name. Drives both dimensions. */
+  schemaMap: Record<string, string>;
+  /** Forwarded to {@link transformSql} (round-trip validation, extra passes). */
+  transform?: TransformSqlOptions;
+}
+
+export interface SchemaTranspiler {
+  /**
+   * Change-name/path rewrite (the pgpm structural dimension): renames the
+   * segment following any `schemas` path segment, e.g.
+   * `schemas/auth/tables/users` → `schemas/tenant_auth/tables/users`.
+   */
+  renameChange: (name: string) => string;
+  /**
+   * SQL body rewrite (the AST dimension): full AST transform of every mapped
+   * schema reference via {@link transformSql}, including PL/pgSQL bodies.
+   * Throws if a mapped schema survives untransformed.
+   */
+  transformScript: (sql: string, ctx: BundleScriptContext) => string;
+  /**
+   * Accumulated report across every script this transpiler has transformed:
+   * schemas found/transformed and any per-script errors.
+   */
+  result: SchemaTransformResult;
+}
+
+/**
+ * Build the caller-supplied callbacks for `transpileBundle` from a single
+ * schema map, so the folder/plan rename and the in-SQL rewrite stay in
+ * lockstep.
+ */
+export function makeSchemaTranspiler(options: SchemaTranspilerOptions): SchemaTranspiler {
+  const mapping = new Map(Object.entries(options.schemaMap));
+  const result: SchemaTransformResult = {
+    schemasFound: new Set(),
+    schemasTransformed: new Map(),
+    errors: []
+  };
+
+  const renameChange = (name: string): string => {
+    const parts = name.split('/');
+    for (let i = 0; i < parts.length - 1; i++) {
+      if (parts[i] === 'schemas' && mapping.has(parts[i + 1])) {
+        parts[i + 1] = mapping.get(parts[i + 1])!;
+      }
+    }
+    return parts.join('/');
+  };
+
+  const transformScript = (sql: string, _ctx: BundleScriptContext): string => {
+    return transformSql(sql, mapping, options.transform, result).content;
+  };
+
+  return { renameChange, transformScript, result };
+}
+
+export interface NamespaceValidatorOptions {
+  /** Schemas the bundle is allowed to create objects in or reference. */
+  allowedSchemas: string[];
+  /**
+   * Also flag statements whose PL/pgSQL bodies execute dynamic SQL — their
+   * references are invisible to the AST, so containment cannot be proven.
+   * Off by default (dynamic SQL is common in legitimate functions).
+   */
+  flagDynamicSql?: boolean;
+}
+
+/**
+ * Build an `applyBundle`-compatible `validateReferences` callback: returns a
+ * description of every schema-qualified object a script creates or references
+ * outside the allowed namespace. Unqualified references resolve via
+ * search_path and are not reported.
+ */
+export function makeNamespaceValidator(
+  options: NamespaceValidatorOptions
+): (sql: string, ctx: BundleScriptContext) => string[] {
+  const allowed = new Set(options.allowedSchemas);
+
+  return (sql: string, _ctx: BundleScriptContext): string[] => {
+    const violations = new Set<string>();
+    for (const facts of classifyStatements(sql)) {
+      for (const ref of [...facts.creates, ...facts.references, ...facts.fkTargets]) {
+        if (ref.schema && !allowed.has(ref.schema)) {
+          violations.add(`${facts.nodeTag}: ${ref.schema}.${ref.name}`);
+        }
+      }
+      if (options.flagDynamicSql && facts.dynamicSql) {
+        violations.add(`${facts.nodeTag}: dynamic SQL — references not statically verifiable`);
+      }
+    }
+    return [...violations];
+  };
+}
diff --git a/packages/transform/src/index.ts b/packages/transform/src/index.ts
index cd447917..be1fced5 100644
--- a/packages/transform/src/index.ts
+++ b/packages/transform/src/index.ts
@@ -1,3 +1,13 @@
+export type {
+  BundleScriptContext,
+  NamespaceValidatorOptions,
+  SchemaTranspiler,
+  SchemaTranspilerOptions,
+} from './bundle-driver';
+export {
+  makeNamespaceValidator,
+  makeSchemaTranspiler,
+} from './bundle-driver';
 export type {
   CategoryProfile,
   ChangeCategory,