feat: Core's Module Database ABI v1 executor, proven against PostgreSQL (ADR 0050)

Implements the first ADR 0050 slice: Core's ORM-neutral executor and its
PostgreSQL evidence. Nothing is wired to modules yet; manifest v8, SDK
adapters, schema metadata, packaging, and Signage are later slices. The
legacy ModuleDatabase facade is unchanged.

Contracts (@ekklesia/contracts, no imports at all):
- ABI version 1; query { text, values, rowMode } returning
  { command, rowCount, rows, fields: [{ name, typeOid }] };
- executor, transaction, and savepoint types with exactly the ABI's
  members; parameter and result value types;
- ModuleDatabaseError { code, sqlState? }: eight stable codes, and a
  SQLSTATE only when PostgreSQL supplied one; static messages, no cause,
  frozen; isModuleDatabaseError recognises it by shape.

Core (createModuleDatabaseExecutor over the API's existing pool):
- one statement per query, enforced by forcing the extended query
  protocol so PostgreSQL itself refuses a second statement (42601);
  no SQL parsing;
- parameters: null, boolean, number, bigint, string, Uint8Array, and
  rectangular arrays of them; everything else refused before sending;
- a Core-owned decoding table that never consults pg's global parser
  registry: int8, numeric, temporal, and JSON as exact text; bytea as a
  plain Uint8Array; built-in arrays element by element;
- every operation pins TimeZone, DateStyle, IntervalStyle, bytea_output,
  and extra_float_digits, then resets with DISCARD ALL before returning
  the connection, or destroys it when it cannot be reset cleanly;
- callback-scoped transactions with explicit isolation and access mode;
  a COMMIT that PostgreSQL answers with ROLLBACK is reported as failed;
- savepoints named by Core; only the innermost scope is active; scopes
  are revoked when their callback settles;
- a callback that settles with work outstanding is rolled back, never
  committed or released;
- transaction-control statements sent through query are refused by
  command tag and transaction status, and fail the transaction;
- the module ID is carried for Core's attribution only.

Tests:
- 83 integration tests on a database with hostile defaults: queries,
  the one-statement rule, parameters, decoding, errors, transactions,
  savepoints, forgotten awaits, pool safety after every failure class,
  and session state;
- unit tests for encoding, decoding, options, sanitization, and scope
  bookkeeping;
- type-level and source checks that no ORM or driver object crosses
  the boundary.

ADR 0050 is Accepted.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

core/src/modules/database-abi.ts

@@ -0,0 +1,563 @@
+import {
+  MODULE_DATABASE_ABI_VERSION,
+  type ModuleDatabaseArrayRow,
+  ModuleDatabaseError,
+  type ModuleDatabaseErrorCode,
+  type ModuleDatabaseExecutor,
+  type ModuleDatabaseField,
+  type ModuleDatabaseObjectRow,
+  type ModuleDatabaseQueryable,
+  type ModuleDatabaseQueryResult,
+  type ModuleDatabaseTransaction,
+  type ModuleId,
+  moduleIdSchema,
+} from "@ekklesia/contracts";
+import { DatabaseError, type Pool, type PoolClient, type QueryArrayConfig } from "pg";
+import {
+  decodeModuleDatabaseRow,
+  encodeModuleDatabaseParameters,
+  rawTextTypes,
+} from "./database-abi-values.js";
+
+/**
+ * Core's Module Database ABI v1 executor (ADR 0050).
+ *
+ * A module hands Core SQL text, ordered parameter values, and a row mode; Core hands back decoded
+ * rows, column metadata, and stable errors. No ORM, driver, pool, client, or connection object ever
+ * crosses in either direction. The executor is built over the one pool the API already owns
+ * (ADR 0016) and never closes it.
+ *
+ * This is a correctness and compatibility boundary, **not a security sandbox**: a trusted module can
+ * still send any SQL its database role permits. Nothing here inspects table names.
+ *
+ * ### Connections and session state
+ *
+ * Every ABI operation, a top-level statement or a whole transaction, borrows a connection from the
+ * pool, pins the session settings the ABI's decoding depends on, does its work, and resets the
+ * session with `DISCARD ALL` before returning the connection. So no setting, temporary table,
+ * listener, advisory lock, prepared statement, or role change a module makes survives the operation
+ * that made it, and nothing the ABI pinned reaches the pool's other users. A connection that cannot
+ * be reset cleanly, or that is not idle when the operation ends, is destroyed rather than returned.
+ * `DISCARD ALL` also deallocates named prepared statements; Core uses none on the shared pool.
+ *
+ * ### One statement per `query`
+ *
+ * Every ABI statement is sent with PostgreSQL's extended query protocol, forced with the driver's
+ * `queryMode: "extended"` even when there are no parameters. PostgreSQL itself refuses a Parse
+ * message holding more than one statement (SQLSTATE 42601), using its own SQL grammar, so comments,
+ * quoted literals, and semicolons inside them are never mistaken for a second statement. Core does
+ * not parse SQL. A statement text that holds no statement at all is refused after PostgreSQL reports
+ * it empty.
+ *
+ * ### Transaction control belongs to Core
+ *
+ * A statement whose command tag is transaction control (`BEGIN`, `START`, `COMMIT`, `ROLLBACK`,
+ * `SAVEPOINT`, `RELEASE`, `PREPARE`), or that leaves the connection's transaction status other than
+ * expected, is refused. PostgreSQL has already run it by then, so inside a transaction it also marks
+ * the transaction failed: Core rolls back and never commits it. The command tag and the protocol's
+ * transaction status come from PostgreSQL, not from parsing the SQL.
+ */
+
+/** The settings the ABI's decoding and determinism depend on, pinned for every ABI operation. */
+const pinSessionStatement =
+  "SET TimeZone TO 'UTC'; SET DateStyle TO 'ISO, MDY'; SET IntervalStyle TO 'postgres'; " +
+  "SET bytea_output TO 'hex'; SET extra_float_digits TO 1";
+const resetSessionStatement = "DISCARD ALL";
+
+const transactionControlCommands: ReadonlySet<string> = new Set([
+  "BEGIN",
+  "COMMIT",
+  "PREPARE",
+  "RELEASE",
+  "ROLLBACK",
+  "SAVEPOINT",
+  "START",
+]);
+
+const isolationStatements: ReadonlyMap<unknown, string> = new Map([
+  ["read committed", "READ COMMITTED"],
+  ["repeatable read", "REPEATABLE READ"],
+  ["serializable", "SERIALIZABLE"],
+]);
+
+/** `pg` 8.22 reports the protocol's ReadyForQuery transaction status through this method, which
+ * its type declarations omit. `acquire` refuses a client without it rather than guessing. */
+type AbiClient = PoolClient & { getTransactionStatus(): string | null };
+
+interface PreparedQuery {
+  readonly config: QueryArrayConfig;
+  readonly rowMode: "array" | "object";
+}
+
+interface RawResult {
+  readonly command: string | null;
+  readonly fields: readonly { readonly dataTypeID: number; readonly name: string }[];
+  readonly rowCount: number | null;
+  readonly rows: readonly unknown[][];
+}
+
+function databaseError(code: ModuleDatabaseErrorCode, cause?: unknown): ModuleDatabaseError {
+  // Only PostgreSQL's own SQLSTATE survives. The driver's message, detail, hint, position, and
+  // object names, and every non-PostgreSQL error, are dropped here.
+  if (cause instanceof DatabaseError && typeof cause.code === "string") {
+    return new ModuleDatabaseError(code, { sqlState: cause.code });
+  }
+  return new ModuleDatabaseError(code);
+}
+
+/** A PostgreSQL error leaves the connection usable; anything else (a dropped connection, a
+ * client-side timeout) may leave it mid-protocol, so it must be destroyed. */
+function connectionSurvives(error: unknown): boolean {
+  return error instanceof DatabaseError;
+}
+
+function prepareQuery(request: unknown): PreparedQuery {
+  if (typeof request !== "object" || request === null || Array.isArray(request)) {
+    throw new ModuleDatabaseError("MODULE_DATABASE_REQUEST_INVALID");
+  }
+  for (const key of Object.keys(request)) {
+    if (key !== "text" && key !== "values" && key !== "rowMode") {
+      throw new ModuleDatabaseError("MODULE_DATABASE_REQUEST_INVALID");
+    }
+  }
+  const { rowMode, text, values } = request as Record<string, unknown>;
+  if (typeof text !== "string" || text.length === 0) {
+    throw new ModuleDatabaseError("MODULE_DATABASE_REQUEST_INVALID");
+  }
+  if (rowMode !== undefined && rowMode !== "object" && rowMode !== "array") {
+    throw new ModuleDatabaseError("MODULE_DATABASE_REQUEST_INVALID");
+  }
+  const config = {
+    queryMode: "extended",
+    rowMode: "array",
+    text,
+    types: rawTextTypes,
+    values: encodeModuleDatabaseParameters(values),
+  };
+  return { config: config as unknown as QueryArrayConfig, rowMode: rowMode ?? "object" };
+}
+
+function beginStatement(options: unknown): string {
+  if (options === undefined) {
+    return "BEGIN ISOLATION LEVEL READ COMMITTED READ WRITE";
+  }
+  if (typeof options !== "object" || options === null || Array.isArray(options)) {
+    throw new ModuleDatabaseError("MODULE_DATABASE_TRANSACTION_OPTION_INVALID");
+  }
+  for (const key of Object.keys(options)) {
+    if (key !== "isolation" && key !== "readOnly") {
+      throw new ModuleDatabaseError("MODULE_DATABASE_TRANSACTION_OPTION_INVALID");
+    }
+  }
+  const { isolation, readOnly } = options as Record<string, unknown>;
+  const level = isolation === undefined ? "READ COMMITTED" : isolationStatements.get(isolation);
+  if (level === undefined || (readOnly !== undefined && typeof readOnly !== "boolean")) {
+    throw new ModuleDatabaseError("MODULE_DATABASE_TRANSACTION_OPTION_INVALID");
+  }
+  return `BEGIN ISOLATION LEVEL ${level} ${readOnly === true ? "READ ONLY" : "READ WRITE"}`;
+}
+
+function buildResult(
+  raw: RawResult,
+  rowMode: "array" | "object",
+): ModuleDatabaseQueryResult<ModuleDatabaseArrayRow | ModuleDatabaseObjectRow> {
+  if (typeof raw.command !== "string" || raw.command === "") {
+    // PostgreSQL answered with EmptyQueryResponse: the text held no statement.
+    throw new ModuleDatabaseError("MODULE_DATABASE_REQUEST_INVALID");
+  }
+  const fields: readonly ModuleDatabaseField[] = Object.freeze(
+    raw.fields.map((field) => Object.freeze({ name: field.name, typeOid: field.dataTypeID })),
+  );
+  const decoded = raw.rows.map((row) => decodeModuleDatabaseRow(fields, row));
+  let rows: readonly (ModuleDatabaseArrayRow | ModuleDatabaseObjectRow)[];
+  if (rowMode === "array") {
+    rows = decoded;
+  } else {
+    if (new Set(fields.map((field) => field.name)).size !== fields.length) {
+      // Object rows cannot hold two columns with one name; refusing beats dropping one.
+      throw new ModuleDatabaseError("MODULE_DATABASE_REQUEST_INVALID");
+    }
+    // `Object.fromEntries` defines properties, so a column named `__proto__` stays a column.
+    rows = decoded.map((row) =>
+      Object.fromEntries(fields.map((field, index) => [field.name, row[index] ?? null])),
+    );
+  }
+  return Object.freeze({
+    command: raw.command,
+    fields,
+    rowCount: raw.rowCount ?? null,
+    rows: Object.freeze(rows),
+  });
+}
+
+/** A borrowed client's `error` events are already reported through the statement they interrupt.
+ * The pool only listens to idle clients, so without this a connection the server terminates while
+ * borrowed would surface as an unhandled `error` event. */
+function ignoreClientError(): void {}
+
+function destroy(client: AbiClient): void {
+  client.removeListener("error", ignoreClientError);
+  client.release(true);
+}
+
+async function acquire(pool: Pool, failure: ModuleDatabaseErrorCode): Promise<AbiClient> {
+  let client: AbiClient;
+  try {
+    client = (await pool.connect()) as AbiClient;
+  } catch (error) {
+    throw databaseError(failure, error);
+  }
+  client.on("error", ignoreClientError);
+  if (typeof client.getTransactionStatus !== "function") {
+    destroy(client);
+    throw new ModuleDatabaseError(failure);
+  }
+  try {
+    await client.query(pinSessionStatement);
+  } catch (error) {
+    destroy(client);
+    throw databaseError(failure, error);
+  }
+  return client;
+}
+
+/** Returns a connection to the pool only when it is idle and resets cleanly; destroys it
+ * otherwise. Never throws. */
+async function relinquish(client: AbiClient, healthy: boolean): Promise<void> {
+  if (!healthy || client.getTransactionStatus() !== "I") {
+    destroy(client);
+    return;
+  }
+  try {
+    await client.query(resetSessionStatement);
+  } catch {
+    destroy(client);
+    return;
+  }
+  client.removeListener("error", ignoreClientError);
+  client.release();
+}
+
+/** One open scope: a transaction or a savepoint inside it. */
+interface Scope {
+  activeChild: Scope | undefined;
+  readonly children: Set<Scope>;
+  closed: boolean;
+  /** Operations started through this scope's executor that have not settled yet. */
+  pending: number;
+}
+
+interface TransactionState {
+  readonly client: AbiClient;
+  healthy: boolean;
+  /** Set when the transaction can no longer be committed: transaction control sent through
+   * `query`, or a savepoint that could not be undone. */
+  failure: ModuleDatabaseError | undefined;
+  finished: boolean;
+  /** Settled-never-rejecting shadows of every statement sent on the connection. */
+  readonly inflight: Set<Promise<void>>;
+  savepoints: number;
+}
+
+function newScope(parent?: Scope): Scope {
+  const scope: Scope = { activeChild: undefined, children: new Set(), closed: false, pending: 0 };
+  parent?.children.add(scope);
+  return scope;
+}
+
+function closeScope(scope: Scope): void {
+  scope.closed = true;
+  for (const child of scope.children) {
+    closeScope(child);
+  }
+}
+
+function assertActive(scope: Scope): void {
+  if (scope.closed) {
+    throw new ModuleDatabaseError("MODULE_DATABASE_SCOPE_CLOSED");
+  }
+  if (scope.activeChild !== undefined) {
+    throw new ModuleDatabaseError("MODULE_DATABASE_SCOPE_INACTIVE");
+  }
+}
+
+function track<T>(state: TransactionState, promise: Promise<T>): Promise<T> {
+  const shadow = promise.then(
+    () => undefined,
+    () => undefined,
+  );
+  state.inflight.add(shadow);
+  void shadow.then(() => state.inflight.delete(shadow));
+  return promise;
+}
+
+/** Waits until every statement already sent has settled, including any sent while waiting. */
+async function drain(state: TransactionState): Promise<void> {
+  while (state.inflight.size > 0) {
+    await Promise.all([...state.inflight]);
+  }
+}
+
+/** Runs one of Core's own transaction-control statements. Refuses, without sending anything, once
+ * the transaction has finished. */
+async function control(state: TransactionState, statement: string): Promise<void> {
+  if (state.finished) {
+    throw new ModuleDatabaseError("MODULE_DATABASE_SCOPE_CLOSED");
+  }
+  try {
+    await track(state, state.client.query(statement));
+  } catch (error) {
+    if (!connectionSurvives(error)) {
+      state.healthy = false;
+    }
+    throw databaseError("MODULE_DATABASE_TRANSACTION_FAILED", error);
+  }
+}
+
+async function rollback(state: TransactionState): Promise<void> {
+  try {
+    await state.client.query("ROLLBACK");
+  } catch {
+    state.healthy = false;
+  }
+}
+
+type Outcome<T> = { readonly value: T } | { readonly error: unknown };
+
+async function settle<T>(run: () => Promise<T> | T): Promise<Outcome<T>> {
+  try {
+    return { value: await run() };
+  } catch (error) {
+    return { error };
+  }
+}
+
+const moduleByExecutor = new WeakMap<object, ModuleId>();
+
+/** Which module an ABI executor, or a transaction or savepoint executor derived from it, belongs
+ * to. For Core's own logging, diagnostics, and attribution; never exposed to modules. */
+export function moduleDatabaseExecutorModuleId(executor: object): ModuleId | undefined {
+  return moduleByExecutor.get(executor);
+}
+
+export interface ModuleDatabaseExecutorOptions {
+  /** The module this executor serves. Carried for attribution only: the ABI enforces no table
+   * ownership at run time (ADR 0050). */
+  readonly moduleId: ModuleId;
+}
+
+/**
+ * Creates one module's ABI v1 executor over the API's existing pool. Synchronous and free of I/O:
+ * nothing touches the database until the module calls it. The returned object, and every
+ * transaction and savepoint executor it hands out, is frozen and holds exactly the ABI's members.
+ */
+export function createModuleDatabaseExecutor(
+  pool: Pool,
+  options: ModuleDatabaseExecutorOptions,
+): ModuleDatabaseExecutor {
+  const parsedModuleId = moduleIdSchema.safeParse(options.moduleId);
+  if (!parsedModuleId.success) {
+    throw new TypeError("A module database executor needs a valid module ID.");
+  }
+  const moduleId = parsedModuleId.data;
+
+  async function query(
+    request: unknown,
+  ): Promise<ModuleDatabaseQueryResult<ModuleDatabaseArrayRow | ModuleDatabaseObjectRow>> {
+    const prepared = prepareQuery(request);
+    const client = await acquire(pool, "MODULE_DATABASE_QUERY_FAILED");
+    let healthy = true;
+    try {
+      let raw: RawResult;
+      try {
+        raw = (await client.query(prepared.config)) as unknown as RawResult;
+      } catch (error) {
+        healthy = connectionSurvives(error);
+        throw databaseError("MODULE_DATABASE_QUERY_FAILED", error);
+      }
+      if (
+        (raw.command !== null && transactionControlCommands.has(raw.command)) ||
+        client.getTransactionStatus() !== "I"
+      ) {
+        // The connection is destroyed below if the statement left a transaction open.
+        throw new ModuleDatabaseError("MODULE_DATABASE_REQUEST_INVALID");
+      }
+      return buildResult(raw, prepared.rowMode);
+    } finally {
+      await relinquish(client, healthy);
+    }
+  }
+
+  function scopeExecutor(state: TransactionState, scope: Scope): ModuleDatabaseTransaction {
+    async function scopeQuery(
+      request: unknown,
+    ): Promise<ModuleDatabaseQueryResult<ModuleDatabaseArrayRow | ModuleDatabaseObjectRow>> {
+      assertActive(scope);
+      const prepared = prepareQuery(request);
+      scope.pending += 1;
+      try {
+        let raw: RawResult;
+        try {
+          raw = (await track(state, state.client.query(prepared.config))) as unknown as RawResult;
+        } catch (error) {
+          if (!connectionSurvives(error)) {
+            state.healthy = false;
+          }
+          throw databaseError("MODULE_DATABASE_QUERY_FAILED", error);
+        }
+        if (
+          (raw.command !== null && transactionControlCommands.has(raw.command)) ||
+          state.client.getTransactionStatus() === "I"
+        ) {
+          state.failure ??= new ModuleDatabaseError("MODULE_DATABASE_REQUEST_INVALID");
+          throw new ModuleDatabaseError("MODULE_DATABASE_REQUEST_INVALID");
+        }
+        return buildResult(raw, prepared.rowMode);
+      } finally {
+        scope.pending -= 1;
+      }
+    }
+
+    async function savepoint<T>(
+      callback: (savepoint: ModuleDatabaseTransaction) => Promise<T> | T,
+    ): Promise<T> {
+      assertActive(scope);
+      if (typeof callback !== "function") {
+        throw new ModuleDatabaseError("MODULE_DATABASE_REQUEST_INVALID");
+      }
+      scope.pending += 1;
+      const child = newScope(scope);
+      scope.activeChild = child;
+      state.savepoints += 1;
+      // Core's own identifier: a fixed prefix and a counter, never anything a module supplied.
+      const name = `ekklesia_savepoint_${state.savepoints}`;
+      try {
+        await control(state, `SAVEPOINT ${name}`);
+        if (child.closed) {
+          throw new ModuleDatabaseError("MODULE_DATABASE_SCOPE_CLOSED");
+        }
+        const outcome = await settle(() => callback(scopeExecutor(state, child)));
+        const outstanding = child.pending > 0;
+        closeScope(child);
+        await drain(state);
+        if (scope.closed) {
+          // The enclosing transaction finished first; it rolls back, and nothing more is sent.
+          throw new ModuleDatabaseError("MODULE_DATABASE_SCOPE_CLOSED");
+        }
+        if (outstanding || "error" in outcome) {
+          try {
+            await control(state, `ROLLBACK TO SAVEPOINT ${name}`);
+            if (!outstanding) {
+              await control(state, `RELEASE SAVEPOINT ${name}`);
+            }
+          } catch (error) {
+            state.failure ??= new ModuleDatabaseError("MODULE_DATABASE_TRANSACTION_FAILED");
+            throw error;
+          }
+          if (outstanding) {
+            throw new ModuleDatabaseError("MODULE_DATABASE_SCOPE_WORK_OUTSTANDING");
+          }
+          throw (outcome as { readonly error: unknown }).error;
+        }
+        try {
+          await control(state, `RELEASE SAVEPOINT ${name}`);
+        } catch (releaseError) {
+          // Typically a failed statement left the transaction aborted. Undo the savepoint so the
+          // transaction stays usable, and report that this savepoint did not complete.
+          try {
+            await control(state, `ROLLBACK TO SAVEPOINT ${name}`);
+            await control(state, `RELEASE SAVEPOINT ${name}`);
+          } catch {
+            state.failure ??= new ModuleDatabaseError("MODULE_DATABASE_TRANSACTION_FAILED");
+          }
+          throw releaseError;
+        }
+        return (outcome as { readonly value: T }).value;
+      } finally {
+        closeScope(child);
+        if (scope.activeChild === child) {
+          scope.activeChild = undefined;
+        }
+        scope.pending -= 1;
+      }
+    }
+
+    const executor = Object.freeze({
+      abiVersion: MODULE_DATABASE_ABI_VERSION,
+      query: scopeQuery as ModuleDatabaseQueryable["query"],
+      savepoint,
+    });
+    moduleByExecutor.set(executor, moduleId);
+    return executor;
+  }
+
+  async function transaction<T>(
+    callback: (transaction: ModuleDatabaseTransaction) => Promise<T> | T,
+    options?: unknown,
+  ): Promise<T> {
+    if (typeof callback !== "function") {
+      throw new ModuleDatabaseError("MODULE_DATABASE_REQUEST_INVALID");
+    }
+    const begin = beginStatement(options);
+    const client = await acquire(pool, "MODULE_DATABASE_TRANSACTION_FAILED");
+    const state: TransactionState = {
+      client,
+      failure: undefined,
+      finished: false,
+      healthy: true,
+      inflight: new Set(),
+      savepoints: 0,
+    };
+    try {
+      try {
+        await client.query(begin);
+      } catch (error) {
+        state.healthy = connectionSurvives(error);
+        throw databaseError("MODULE_DATABASE_TRANSACTION_FAILED", error);
+      }
+      const scope = newScope();
+      const outcome = await settle(() => callback(scopeExecutor(state, scope)));
+      const outstanding = scope.pending > 0;
+      closeScope(scope);
+      await drain(state);
+      state.finished = true;
+
+      if (outstanding) {
+        await rollback(state);
+        throw new ModuleDatabaseError("MODULE_DATABASE_SCOPE_WORK_OUTSTANDING");
+      }
+      if ("error" in outcome) {
+        await rollback(state);
+        throw outcome.error;
+      }
+      if (state.failure !== undefined) {
+        await rollback(state);
+        throw state.failure;
+      }
+      let committed: { readonly command: string | null };
+      try {
+        committed = await client.query("COMMIT");
+      } catch (error) {
+        state.healthy = connectionSurvives(error);
+        throw databaseError("MODULE_DATABASE_TRANSACTION_FAILED", error);
+      }
+      if (committed.command !== "COMMIT") {
+        // PostgreSQL answers COMMIT with ROLLBACK when a failed statement had aborted the
+        // transaction. Nothing was committed, and PostgreSQL supplied no SQLSTATE to report.
+        throw new ModuleDatabaseError("MODULE_DATABASE_TRANSACTION_FAILED");
+      }
+      return outcome.value;
+    } finally {
+      state.finished = true;
+      await relinquish(client, state.healthy);
+    }
+  }
+
+  const executor = Object.freeze({
+    abiVersion: MODULE_DATABASE_ABI_VERSION,
+    query: query as ModuleDatabaseQueryable["query"],
+    transaction: transaction as ModuleDatabaseExecutor["transaction"],
+  });
+  moduleByExecutor.set(executor, moduleId);
+  return executor;
+}