fix(postgres): fail fast when SQL loader directory cannot be resolved

src/postgres/sql-loader.ts

@@ -1,5 +1,26 @@
 import { readFileSync } from 'fs';
-import { join } from 'path';
+import { dirname, join } from 'path';
+import { fileURLToPath } from 'url';
+
+function getDirname(): string {
+  if (typeof __dirname !== 'undefined' && __dirname) {
+    return __dirname;
+  }
+  const stack = new Error().stack || '';
+  for (const line of stack.split('\n')) {
+    const match = line.match(/(file:\/\/\/[^\s)]+)/);
+    if (match) {
+      try {
+        return dirname(fileURLToPath(match[1]));
+      } catch {
+        // continue searching
+      }
+    }
+  }
+  throw new Error('Could not determine sql-loader directory path');
+}
+
+const currentDir = getDirname();
 
 /**
  * Loads a migration's SQL from its `.sql` file — the portable source of truth
@@ -10,7 +31,7 @@ import { join } from 'path';
  * analogous to how the Lua scripts are bundled), so the same relative lookup
  * works at runtime.
  */
-const MIGRATIONS_DIR = join(__dirname, 'migrations');
+const MIGRATIONS_DIR = join(currentDir, 'migrations');
 
 /**
  * Runtime queries live under `commands/`. Each `.sql` file is one parameterized
@@ -20,7 +41,7 @@ const MIGRATIONS_DIR = join(__dirname, 'migrations');
  * Python/Elixir/PHP/Rust ports (mirroring how the Redis backend's `.lua`
  * scripts never hardcode the key prefix).
  */
-const COMMANDS_DIR = join(__dirname, 'commands');
+const COMMANDS_DIR = join(currentDir, 'commands');
 
 const migrationCache = new Map<string, string>();
 const commandCache = new Map<string, string>();

tests/postgres/sql_loader.test.ts

@@ -0,0 +1,38 @@
+import { describe, expect, it, vi } from 'vitest';
+import {
+  loadCommandSql,
+  loadMigrationSql,
+} from '../../src/postgres/sql-loader';
+
+describe('PostgreSQL SQL Loader', () => {
+  it('loads migration SQL files without throwing', () => {
+    const migration = loadMigrationSql('0001_schema.sql');
+    expect(typeof migration).toBe('string');
+    expect(migration.length).toBeGreaterThan(0);
+    expect(migration).toContain('CREATE TABLE');
+  });
+
+  it('loads command SQL files without throwing', () => {
+    const command = loadCommandSql('add_job');
+    expect(typeof command).toBe('string');
+    expect(command.length).toBeGreaterThan(0);
+  });
+
+  it('caches loaded SQL content for subsequent calls', async () => {
+    vi.resetModules();
+    const readFileSync = vi.fn(() => 'SELECT 1;');
+
+    vi.doMock('fs', () => ({
+      readFileSync,
+    }));
+
+    const { loadCommandSql: loadCommandSqlFresh } =
+      await import('../../src/postgres/sql-loader');
+
+    expect(loadCommandSqlFresh('add_job')).toBe('SELECT 1;');
+    expect(loadCommandSqlFresh('add_job')).toBe('SELECT 1;');
+
+    expect(readFileSync).toHaveBeenCalledTimes(1);
+    vi.doUnmock('fs');
+  });
+});