Stop dotenv printing its banner onto the MCP stdout transport

src/db.ts

@@ -8,7 +8,14 @@ import * as dotenv from 'dotenv';
 // imports) already called `import 'dotenv/config'`, DATABASE_URL from ./.env
 // would otherwise shadow the explicit path here, silently routing all writes
 // to local Docker. Observed 2026-04-07 → 2026-04-13 (6 days of events drift).
-dotenv.config({ path: process.env.DOTENV_CONFIG_PATH, override: true });
+//
+// `quiet: true` is equally load-bearing: dotenv defaults it to FALSE since
+// 17.0.0 and prints its injection banner via console.log — onto stdout, which
+// for the MCP server is the JSON-RPC transport itself. The banner lands ahead
+// of the initialize reply; clients that skip unparseable lines tolerate it,
+// clients that don't see a corrupt stream and register zero tools with no
+// error to read.
+dotenv.config({ path: process.env.DOTENV_CONFIG_PATH, override: true, quiet: true });
 import { drizzle } from 'drizzle-orm/node-postgres';
 import pg from 'pg';
 import * as schema from './schema.js';

tests/db-guard.test.ts

@@ -194,7 +194,7 @@ describe('helpers.ts resolves DATABASE_URL the same way src/db.ts does', () => {
 
   it('helpers.ts overrides from DOTENV_CONFIG_PATH, like db.ts', () => {
     expect(read('./integration/helpers.ts')).toMatch(
-      /dotenv\.config\(\{\s*path:\s*process\.env\.DOTENV_CONFIG_PATH,\s*override:\s*true\s*\}\)/,
+      /dotenv\.config\(\{\s*path:\s*process\.env\.DOTENV_CONFIG_PATH,\s*override:\s*true,\s*quiet:\s*true\s*\}\)/,
     );
   });
 
@@ -209,7 +209,7 @@ describe('helpers.ts resolves DATABASE_URL the same way src/db.ts does', () => {
     // If db.ts ever changes its resolution, this pairing is stale and the two
     // pools can diverge again — fail here rather than against a live database.
     expect(read('../src/db.ts')).toMatch(
-      /dotenv\.config\(\{\s*path:\s*process\.env\.DOTENV_CONFIG_PATH,\s*override:\s*true\s*\}\)/,
+      /dotenv\.config\(\{\s*path:\s*process\.env\.DOTENV_CONFIG_PATH,\s*override:\s*true,\s*quiet:\s*true\s*\}\)/,
     );
   });
 });

tests/env-loading.test.ts

@@ -37,6 +37,15 @@ describe('env loading invariants', () => {
     expect(src).toMatch(/dotenv\.config\([^)]*override:\s*true/);
   });
 
+  it('db.ts must pass { quiet: true } — stdout is the MCP transport', () => {
+    // dotenv defaults quiet:false since 17.0.0 and logs its injection banner
+    // with console.log — i.e. onto stdout, which for the MCP server IS the
+    // JSON-RPC transport. A client that does not skip unparseable lines sees
+    // a corrupt stream and registers no tools, with no error to read.
+    const src = readFileSync(join(repoRoot, 'src/db.ts'), 'utf8');
+    expect(src).toMatch(/dotenv\.config\([^)]*quiet:\s*true/);
+  });
+
   it('dotenv { override: true } overrides a pre-set env var', () => {
     // Guard against dotenv upgrade silently changing override semantics.
     const tmp = mkdtempSync(join(tmpdir(), 'env-test-'));

tests/integration/helpers.ts

@@ -23,7 +23,7 @@ const { Pool } = pg;
 //   DATABASE_URL=<localhost> DOTENV_CONFIG_PATH=<managed> vitest
 // would satisfy the guard and then write to the managed database anyway.
 // tests/db-guard.test.ts pins this pairing at the source level.
-dotenv.config({ path: process.env.DOTENV_CONFIG_PATH, override: true });
+dotenv.config({ path: process.env.DOTENV_CONFIG_PATH, override: true, quiet: true });
 
 // Guard against running this suite against a shared managed database.
 // Enforced at module load, before the pool is constructed, so it protects