Harden embedded postgres adoption on startup

server/src/index.ts

@@ -10,6 +10,7 @@ import { and, eq } from "drizzle-orm";
 import {
   createDb,
   ensurePostgresDatabase,
+  getPostgresDataDirectory,
   inspectMigrations,
   applyPendingMigrations,
   reconcilePendingMigrationHistory,
@@ -322,6 +323,13 @@ export async function startServer(): Promise<StartedServer> {
     } else {
       const configuredAdminConnectionString = `postgres://paperclip:paperclip@127.0.0.1:${configuredPort}/postgres`;
       try {
+        const actualDataDir = await getPostgresDataDirectory(configuredAdminConnectionString);
+        if (
+          typeof actualDataDir !== "string" ||
+          resolve(actualDataDir) !== resolve(dataDir)
+        ) {
+          throw new Error("reachable postgres does not use the expected embedded data directory");
+        }
         await ensurePostgresDatabase(configuredAdminConnectionString, "paperclip");
         logger.warn(
           `Embedded PostgreSQL appears to already be reachable without a pid file; reusing existing server on configured port ${configuredPort}`,