diff --git a/apps/gateway/src/app.module.spec.ts b/apps/gateway/src/app.module.spec.ts
new file mode 100644
index 00000000..66a2d237
--- /dev/null
+++ b/apps/gateway/src/app.module.spec.ts
@@ -0,0 +1,624 @@
+import 'reflect-metadata';
+import { mkdtemp, mkdir, readFile, rm, writeFile } from 'node:fs/promises';
+import * as nodeOs from 'node:os';
+import { dirname, isAbsolute, join, relative, resolve } from 'node:path';
+import * as nodeUrl from 'node:url';
+import { MODULE_METADATA } from '@nestjs/common/constants.js';
+import { describe, expect, it, vi } from 'vitest';
+import type { MosaicConfig } from '@mosaicstack/config';
+
+interface ComposedModuleGraph {
+  imports: readonly unknown[];
+  federationModule: unknown;
+  bootLogLines: readonly string[];
+  mosaicConfig: MosaicConfig;
+  resolvedConfigPath: string;
+}
+
+type StorageTier = 'local' | 'standalone' | 'federated';
+
+interface ModuleGraphFixture {
+  tempRoot: string;
+  anchor: string;
+  homePath: string;
+  cwdPath: string;
+  monorepoRootEnvPath: string;
+  gatewayLocalEnvPath: string;
+  daemonEnvPath: string;
+  monorepoRootConfigPath: string;
+  gatewayLocalConfigPath: string;
+}
+
+interface ModuleGraphFixtureOptions {
+  rootEnvMode?: 'present' | 'absent';
+  rootTier?: StorageTier;
+  rootEnvContents?: string;
+  redactionMarker?: string;
+  gatewayLocalTier?: StorageTier;
+  gatewayLocalEnvContents?: string;
+  daemonEnvContents?: string;
+  inheritedTier?: StorageTier;
+  expectedProcessTier?: string;
+  setup?: (fixture: ModuleGraphFixture) => Promise<void>;
+}
+
+// Each case uses vi.resetModules() and re-imports the full gateway graph for distinct ambient FS/env; CI needs headroom, while this still guards genuine hangs.
+const MODULE_IMPORT_TIMEOUT_MS = 120_000;
+const MONOREPO_ROOT_DOTENV_LABEL = 'monorepo-root .env';
+const DAEMON_DOTENV_LABEL = 'daemon .env';
+
+function configJson(tier: StorageTier): string {
+  if (tier === 'local') {
+    return JSON.stringify({
+      tier,
+      storage: { type: 'pglite', dataDir: '.mosaic/storage-pglite' },
+      queue: { type: 'local', dataDir: '.mosaic/queue' },
+      memory: { type: 'keyword' },
+    });
+  }
+
+  return JSON.stringify({
+    tier,
+    storage: { type: 'postgres', url: 'postgresql://fixture.invalid/mosaic' },
+    queue: { type: 'bullmq' },
+    memory: { type: tier === 'federated' ? 'pgvector' : 'keyword' },
+  });
+}
+
+function snapshotProcessEnv(): Record<string, string | undefined> {
+  return { ...process.env };
+}
+
+function restoreProcessEnv(snapshot: Record<string, string | undefined>): void {
+  for (const key of Object.keys(process.env)) {
+    if (!(key in snapshot)) {
+      delete process.env[key];
+    }
+  }
+
+  for (const [key, value] of Object.entries(snapshot)) {
+    if (value === undefined) {
+      delete process.env[key];
+      continue;
+    }
+
+    process.env[key] = value;
+  }
+}
+
+function expectPathUnderTempRoot(path: string, tempRoot: string): void {
+  const relativePath = relative(tempRoot, path);
+  expect(relativePath === '' || (!relativePath.startsWith('..') && !isAbsolute(relativePath))).toBe(
+    true,
+  );
+}
+
+async function writeFixture(path: string, contents: string, tempRoot: string): Promise<void> {
+  expectPathUnderTempRoot(path, tempRoot);
+  await mkdir(dirname(path), { recursive: true });
+  await writeFile(path, contents, 'utf8');
+}
+
+interface ConfigModuleProvider {
+  provide: string;
+  useFactory: () => MosaicConfig;
+}
+
+function isConfigModuleProvider(value: unknown): value is ConfigModuleProvider {
+  if (typeof value !== 'object' || value === null) {
+    return false;
+  }
+
+  if (!('provide' in value) || typeof value.provide !== 'string') {
+    return false;
+  }
+
+  return 'useFactory' in value && typeof value.useFactory === 'function';
+}
+
+function singleBootLogLine(bootLogLines: readonly string[]): string {
+  expect(bootLogLines).toHaveLength(1);
+  const [bootLogLine] = bootLogLines;
+  if (bootLogLine === undefined) {
+    throw new Error('Expected a single boot log line');
+  }
+
+  return bootLogLine;
+}
+
+function expectBootLogLine(
+  bootLogLines: readonly string[],
+  tier: StorageTier,
+  source: string,
+): void {
+  const bootLogLine = singleBootLogLine(bootLogLines);
+
+  expect(bootLogLine).toContain(`storage tier=${tier}`);
+  expect(bootLogLine).toContain(`source=${source}`);
+}
+
+async function loadModuleGraphFromDotenv(
+  options: ModuleGraphFixtureOptions,
+): Promise<ComposedModuleGraph> {
+  const originalEnv = snapshotProcessEnv();
+  const tempRoot = await mkdtemp(join(nodeOs.tmpdir(), 'mosaic-gateway-module-'));
+  let consoleInfoSpy: ReturnType<typeof vi.spyOn> | undefined;
+  let cwdSpy: ReturnType<typeof vi.spyOn> | undefined;
+
+  try {
+    const anchor = join(tempRoot, 'anchored', 'apps', 'gateway', 'src');
+    const homePath = join(tempRoot, 'home');
+    const cwdPath = join(tempRoot, 'ambient', 'parent', 'cwd');
+    const fixture: ModuleGraphFixture = {
+      tempRoot,
+      anchor,
+      homePath,
+      cwdPath,
+      monorepoRootEnvPath: resolve(anchor, '../../..', '.env'),
+      gatewayLocalEnvPath: resolve(anchor, '..', '.env'),
+      daemonEnvPath: join(homePath, '.config', 'mosaic', 'gateway', '.env'),
+      monorepoRootConfigPath: resolve(anchor, '../../..', 'mosaic.config.json'),
+      gatewayLocalConfigPath: resolve(anchor, '..', 'mosaic.config.json'),
+    };
+    consoleInfoSpy = vi.spyOn(console, 'info').mockImplementation((): void => undefined);
+
+    for (const path of Object.values(fixture)) {
+      expectPathUnderTempRoot(path, tempRoot);
+    }
+
+    await mkdir(anchor, { recursive: true });
+    await mkdir(cwdPath, { recursive: true });
+
+    if ((options.rootEnvMode ?? 'present') === 'absent') {
+      if (
+        options.rootEnvContents !== undefined ||
+        options.rootTier !== undefined ||
+        options.redactionMarker !== undefined
+      ) {
+        throw new Error('Expected no root env fixture values when rootEnvMode is absent');
+      }
+    } else {
+      if (options.rootEnvContents === undefined && options.rootTier === undefined) {
+        throw new Error('Expected rootTier or rootEnvContents');
+      }
+
+      const rootFixture = options.rootEnvContents ?? `MOSAIC_STORAGE_TIER=${options.rootTier}\n`;
+      const rootFixtureWithMarker = options.redactionMarker
+        ? `${rootFixture}BETTER_AUTH_SECRET=${options.redactionMarker}\n`
+        : rootFixture;
+      await writeFixture(fixture.monorepoRootEnvPath, rootFixtureWithMarker, tempRoot);
+    }
+
+    if (options.daemonEnvContents !== undefined) {
+      await writeFixture(fixture.daemonEnvPath, options.daemonEnvContents, tempRoot);
+    }
+
+    if (options.gatewayLocalEnvContents !== undefined) {
+      await writeFixture(fixture.gatewayLocalEnvPath, options.gatewayLocalEnvContents, tempRoot);
+    } else if (options.gatewayLocalTier !== undefined) {
+      await writeFixture(
+        fixture.gatewayLocalEnvPath,
+        `MOSAIC_STORAGE_TIER=${options.gatewayLocalTier}\n`,
+        tempRoot,
+      );
+    }
+
+    process.env['HOME'] = homePath;
+    delete process.env['MOSAIC_STORAGE_TIER'];
+    delete process.env['DATABASE_URL'];
+    delete process.env['VALKEY_URL'];
+    delete process.env['MOSAIC_GATEWAY_HOME'];
+
+    await options.setup?.(fixture);
+
+    if (options.inheritedTier !== undefined) {
+      process.env['MOSAIC_STORAGE_TIER'] = options.inheritedTier;
+    }
+
+    vi.resetModules();
+    vi.doMock('node:os', () => ({ ...nodeOs, homedir: (): string => homePath }));
+    vi.doMock('node:url', () => ({
+      ...nodeUrl,
+      fileURLToPath: (url: string | URL): string => {
+        const actualPath = nodeUrl.fileURLToPath(url);
+        if (
+          actualPath.endsWith('/apps/gateway/src/env.ts') ||
+          actualPath.endsWith('/apps/gateway/src/env.js')
+        ) {
+          return join(anchor, 'env.ts');
+        }
+        return actualPath;
+      },
+    }));
+    cwdSpy = vi.spyOn(process, 'cwd').mockReturnValue(cwdPath);
+
+    if (options.inheritedTier === undefined) {
+      expect(process.env['MOSAIC_STORAGE_TIER']).toBeUndefined();
+    } else {
+      expect(process.env['MOSAIC_STORAGE_TIER']).toBe(options.inheritedTier);
+    }
+
+    const envModule = await import('./env.js');
+    expect(process.env['MOSAIC_STORAGE_TIER']).toBe(
+      options.expectedProcessTier ?? options.rootTier,
+    );
+
+    const { AppModule } = await import('./app.module.js');
+    const { FederationModule } = await import('./federation/federation.module.js');
+    const imports: unknown = Reflect.getMetadata(MODULE_METADATA.IMPORTS, AppModule);
+
+    if (!Array.isArray(imports)) {
+      throw new Error('AppModule imports metadata is not an array');
+    }
+
+    const { ConfigModule, MOSAIC_CONFIG } = await import('./config/config.module.js');
+    const providers: unknown = Reflect.getMetadata(MODULE_METADATA.PROVIDERS, ConfigModule);
+
+    if (!Array.isArray(providers)) {
+      throw new Error('ConfigModule providers metadata is not an array');
+    }
+
+    const configProvider = providers
+      .filter(isConfigModuleProvider)
+      .find((provider: ConfigModuleProvider): boolean => provider.provide === MOSAIC_CONFIG);
+
+    if (!configProvider) {
+      throw new Error('MOSAIC_CONFIG provider factory not found');
+    }
+
+    return {
+      imports,
+      federationModule: FederationModule,
+      bootLogLines: consoleInfoSpy.mock.calls.map((args: readonly unknown[]): string =>
+        args.map((value: unknown): string => String(value)).join(' '),
+      ),
+      mosaicConfig: configProvider.useFactory(),
+      resolvedConfigPath: envModule.resolveGatewayConfigPath(),
+    };
+  } finally {
+    cwdSpy?.mockRestore();
+    vi.doUnmock('node:url');
+    vi.doUnmock('node:os');
+    vi.resetModules();
+    consoleInfoSpy?.mockRestore();
+    restoreProcessEnv(originalEnv);
+    await rm(tempRoot, { recursive: true, force: true });
+  }
+}
+
+describe('AppModule federation gating', (): void => {
+  it('loads dotenv before tracing and AppModule evaluation', async (): Promise<void> => {
+    const mainSource = await readFile(new URL('./main.ts', import.meta.url), 'utf8');
+    const envImportIndex = mainSource.indexOf("import './env.js';");
+    const tracingImportIndex = mainSource.indexOf("import './tracing.js';");
+    const appModuleImportIndex = mainSource.indexOf("import { AppModule } from './app.module.js';");
+
+    expect(envImportIndex).toBeGreaterThan(-1);
+    expect(envImportIndex).toBeLessThan(tracingImportIndex);
+    expect(envImportIndex).toBeLessThan(appModuleImportIndex);
+  });
+
+  it(
+    'ignores ambient cwd/.env and cwd/../.env files',
+    async (): Promise<void> => {
+      const graph = await loadModuleGraphFromDotenv({
+        rootTier: 'local',
+        setup: async (fixture: ModuleGraphFixture): Promise<void> => {
+          await writeFixture(
+            join(fixture.cwdPath, '.env'),
+            'MOSAIC_STORAGE_TIER=federated\n',
+            fixture.tempRoot,
+          );
+          await writeFixture(
+            resolve(fixture.cwdPath, '..', '.env'),
+            'MOSAIC_STORAGE_TIER=federated\n',
+            fixture.tempRoot,
+          );
+        },
+      });
+
+      expect(graph.imports).not.toContain(graph.federationModule);
+      expectBootLogLine(graph.bootLogLines, 'local', MONOREPO_ROOT_DOTENV_LABEL);
+    },
+    MODULE_IMPORT_TIMEOUT_MS,
+  );
+
+  it(
+    'ignores an ambient cwd/mosaic.config.json federated config',
+    async (): Promise<void> => {
+      const graph = await loadModuleGraphFromDotenv({
+        rootTier: 'local',
+        setup: async (fixture: ModuleGraphFixture): Promise<void> => {
+          await writeFixture(
+            join(fixture.cwdPath, 'mosaic.config.json'),
+            configJson('federated'),
+            fixture.tempRoot,
+          );
+        },
+      });
+
+      expect(graph.imports).not.toContain(graph.federationModule);
+      expectBootLogLine(graph.bootLogLines, 'local', MONOREPO_ROOT_DOTENV_LABEL);
+    },
+    MODULE_IMPORT_TIMEOUT_MS,
+  );
+
+  it(
+    'ignores an ambient cwd/../../mosaic.config.json federated config',
+    async (): Promise<void> => {
+      const graph = await loadModuleGraphFromDotenv({
+        rootTier: 'local',
+        setup: async (fixture: ModuleGraphFixture): Promise<void> => {
+          await writeFixture(
+            resolve(fixture.cwdPath, '../..', 'mosaic.config.json'),
+            configJson('federated'),
+            fixture.tempRoot,
+          );
+        },
+      });
+
+      expect(graph.imports).not.toContain(graph.federationModule);
+      expectBootLogLine(graph.bootLogLines, 'local', MONOREPO_ROOT_DOTENV_LABEL);
+    },
+    MODULE_IMPORT_TIMEOUT_MS,
+  );
+
+  it(
+    'anchored gateway-local config wins monorepo-root config and registers FederationModule',
+    async (): Promise<void> => {
+      let gatewayLocalConfigPath = '';
+      const graph = await loadModuleGraphFromDotenv({
+        rootTier: 'local',
+        setup: async (fixture: ModuleGraphFixture): Promise<void> => {
+          gatewayLocalConfigPath = fixture.gatewayLocalConfigPath;
+          await writeFixture(
+            fixture.gatewayLocalConfigPath,
+            configJson('federated'),
+            fixture.tempRoot,
+          );
+          await writeFixture(fixture.monorepoRootConfigPath, configJson('local'), fixture.tempRoot);
+        },
+      });
+
+      expect(graph.resolvedConfigPath).toBe(gatewayLocalConfigPath);
+      expect(graph.mosaicConfig.tier).toBe('federated');
+      expect(graph.imports).toContain(graph.federationModule);
+      expectBootLogLine(graph.bootLogLines, 'federated', 'mosaic.config.json');
+    },
+    MODULE_IMPORT_TIMEOUT_MS,
+  );
+
+  it(
+    'resolves the daemon-installed GATEWAY_HOME/mosaic.config.json ahead of gateway-local and monorepo-root configs',
+    async (): Promise<void> => {
+      let daemonConfigPath = '';
+      const graph = await loadModuleGraphFromDotenv({
+        rootEnvMode: 'absent',
+        setup: async (fixture: ModuleGraphFixture): Promise<void> => {
+          const externalGatewayHome = join(fixture.tempRoot, 'external-gateway-home');
+          daemonConfigPath = join(externalGatewayHome, 'mosaic.config.json');
+          await writeFixture(daemonConfigPath, configJson('federated'), fixture.tempRoot);
+          await writeFixture(
+            fixture.gatewayLocalConfigPath,
+            configJson('standalone'),
+            fixture.tempRoot,
+          );
+          await writeFixture(fixture.monorepoRootConfigPath, configJson('local'), fixture.tempRoot);
+          process.env['MOSAIC_GATEWAY_HOME'] = externalGatewayHome;
+          process.env['DATABASE_URL'] = 'postgresql://fixture.invalid/mosaic';
+        },
+      });
+
+      expect(graph.resolvedConfigPath).toBe(daemonConfigPath);
+      expect(graph.mosaicConfig.tier).toBe('federated');
+      expect(graph.imports).toContain(graph.federationModule);
+      expectBootLogLine(graph.bootLogLines, 'federated', 'mosaic.config.json');
+    },
+    MODULE_IMPORT_TIMEOUT_MS,
+  );
+
+  it(
+    'logs mosaic.config.json when anchored config and env tiers are both federated',
+    async (): Promise<void> => {
+      const graph = await loadModuleGraphFromDotenv({
+        rootTier: 'federated',
+        setup: async (fixture: ModuleGraphFixture): Promise<void> => {
+          await writeFixture(
+            fixture.monorepoRootConfigPath,
+            configJson('federated'),
+            fixture.tempRoot,
+          );
+        },
+      });
+
+      expect(graph.imports).toContain(graph.federationModule);
+      expectBootLogLine(graph.bootLogLines, 'federated', 'mosaic.config.json');
+    },
+    MODULE_IMPORT_TIMEOUT_MS,
+  );
+
+  it(
+    'logs standalone from a monorepo-root .env DATABASE_URL fallback',
+    async (): Promise<void> => {
+      const graph = await loadModuleGraphFromDotenv({
+        rootEnvContents: 'DATABASE_URL=fixture-database-url\n',
+      });
+
+      expect(graph.imports).not.toContain(graph.federationModule);
+      expectBootLogLine(graph.bootLogLines, 'standalone', MONOREPO_ROOT_DOTENV_LABEL);
+    },
+    MODULE_IMPORT_TIMEOUT_MS,
+  );
+
+  it(
+    'attributes an invalid monorepo-root dotenv tier to the default',
+    async (): Promise<void> => {
+      const graph = await loadModuleGraphFromDotenv({
+        rootEnvContents: 'MOSAIC_STORAGE_TIER=invalid\n',
+        expectedProcessTier: 'invalid',
+      });
+
+      expect(graph.imports).not.toContain(graph.federationModule);
+      expectBootLogLine(graph.bootLogLines, 'local', 'default');
+    },
+    MODULE_IMPORT_TIMEOUT_MS,
+  );
+
+  it(
+    'attributes DATABASE_URL fallback to daemon .env ahead of inherited local tier',
+    async (): Promise<void> => {
+      const graph = await loadModuleGraphFromDotenv({
+        rootEnvMode: 'absent',
+        daemonEnvContents: 'DATABASE_URL=fixture-database-url\n',
+        inheritedTier: 'local',
+        expectedProcessTier: 'local',
+      });
+
+      expect(graph.imports).not.toContain(graph.federationModule);
+      expectBootLogLine(graph.bootLogLines, 'standalone', DAEMON_DOTENV_LABEL);
+    },
+    MODULE_IMPORT_TIMEOUT_MS,
+  );
+
+  it(
+    'daemon .env wins over monorepo-root and gateway-local tier values',
+    async (): Promise<void> => {
+      const graph = await loadModuleGraphFromDotenv({
+        rootTier: 'local',
+        gatewayLocalTier: 'federated',
+        daemonEnvContents: 'MOSAIC_STORAGE_TIER=standalone\n',
+        expectedProcessTier: 'standalone',
+      });
+
+      expect(graph.imports).not.toContain(graph.federationModule);
+      expectBootLogLine(graph.bootLogLines, 'standalone', DAEMON_DOTENV_LABEL);
+    },
+    MODULE_IMPORT_TIMEOUT_MS,
+  );
+
+  it(
+    'inherits process.env.MOSAIC_STORAGE_TIER over daemon, monorepo-root, and gateway-local dotenv values',
+    async (): Promise<void> => {
+      const graph = await loadModuleGraphFromDotenv({
+        rootTier: 'local',
+        gatewayLocalTier: 'federated',
+        daemonEnvContents: 'MOSAIC_STORAGE_TIER=federated\n',
+        inheritedTier: 'standalone',
+        expectedProcessTier: 'standalone',
+      });
+
+      expect(graph.imports).not.toContain(graph.federationModule);
+      expectBootLogLine(graph.bootLogLines, 'standalone', 'process environment');
+    },
+    MODULE_IMPORT_TIMEOUT_MS,
+  );
+
+  it(
+    'gateway-local .env configures the tier and source when the monorepo-root .env is absent',
+    async (): Promise<void> => {
+      const graph = await loadModuleGraphFromDotenv({
+        rootEnvMode: 'absent',
+        gatewayLocalTier: 'federated',
+        expectedProcessTier: 'federated',
+      });
+
+      expect(graph.imports).toContain(graph.federationModule);
+      expectBootLogLine(graph.bootLogLines, 'federated', 'gateway-local .env');
+    },
+    MODULE_IMPORT_TIMEOUT_MS,
+  );
+
+  it(
+    'monorepo-root .env wins over gateway-local tier values',
+    async (): Promise<void> => {
+      const graph = await loadModuleGraphFromDotenv({
+        rootTier: 'standalone',
+        gatewayLocalTier: 'federated',
+      });
+
+      expect(graph.imports).not.toContain(graph.federationModule);
+      expectBootLogLine(graph.bootLogLines, 'standalone', MONOREPO_ROOT_DOTENV_LABEL);
+    },
+    MODULE_IMPORT_TIMEOUT_MS,
+  );
+
+  it.each(['local', 'standalone'] as const)(
+    'does not register FederationModule for the %s tier',
+    async (tier): Promise<void> => {
+      const graph = await loadModuleGraphFromDotenv({ rootTier: tier });
+
+      expect(graph.imports).not.toContain(graph.federationModule);
+      expectBootLogLine(graph.bootLogLines, tier, MONOREPO_ROOT_DOTENV_LABEL);
+    },
+    MODULE_IMPORT_TIMEOUT_MS,
+  );
+
+  it(
+    'registers FederationModule when federated tier is supplied by the anchored monorepo root .env',
+    async (): Promise<void> => {
+      const redactionMarker = 'redaction-fixture-marker';
+      const graph = await loadModuleGraphFromDotenv({
+        rootTier: 'federated',
+        redactionMarker,
+      });
+
+      expect(graph.imports).toContain(graph.federationModule);
+      expectBootLogLine(graph.bootLogLines, 'federated', MONOREPO_ROOT_DOTENV_LABEL);
+      expect(singleBootLogLine(graph.bootLogLines)).not.toContain(redactionMarker);
+    },
+    MODULE_IMPORT_TIMEOUT_MS,
+  );
+
+  it(
+    'MOSAIC_CONFIG provider ignores an ambient cwd/mosaic.config.json config',
+    async (): Promise<void> => {
+      const graph = await loadModuleGraphFromDotenv({
+        rootTier: 'local',
+        setup: async (fixture: ModuleGraphFixture): Promise<void> => {
+          await writeFixture(
+            join(fixture.cwdPath, 'mosaic.config.json'),
+            JSON.stringify({
+              tier: 'federated',
+              storage: {
+                type: 'postgres',
+                url: 'postgresql://ambient-attacker.invalid/mosaic',
+                enableVector: true,
+              },
+              queue: { type: 'bullmq' },
+              memory: { type: 'pgvector' },
+            }),
+            fixture.tempRoot,
+          );
+        },
+      });
+
+      expect(graph.mosaicConfig.tier).toBe('local');
+      expect(graph.mosaicConfig.storage).not.toEqual(
+        expect.objectContaining({ url: 'postgresql://ambient-attacker.invalid/mosaic' }),
+      );
+    },
+    MODULE_IMPORT_TIMEOUT_MS,
+  );
+
+  it(
+    'MOSAIC_CONFIG provider resolves from the anchored monorepo-root mosaic.config.json',
+    async (): Promise<void> => {
+      const graph = await loadModuleGraphFromDotenv({
+        rootTier: 'local',
+        setup: async (fixture: ModuleGraphFixture): Promise<void> => {
+          await writeFixture(
+            fixture.monorepoRootConfigPath,
+            configJson('federated'),
+            fixture.tempRoot,
+          );
+        },
+      });
+
+      expect(graph.mosaicConfig.tier).toBe('federated');
+      expect(graph.mosaicConfig.storage).toEqual(
+        expect.objectContaining({ url: 'postgresql://fixture.invalid/mosaic' }),
+      );
+    },
+    MODULE_IMPORT_TIMEOUT_MS,
+  );
+});
diff --git a/apps/gateway/src/app.module.ts b/apps/gateway/src/app.module.ts
index dc9a6e32..8adfabe8 100644
--- a/apps/gateway/src/app.module.ts
+++ b/apps/gateway/src/app.module.ts
@@ -26,6 +26,16 @@ import { WorkspaceModule } from './workspace/workspace.module.js';
 import { QueueModule } from './queue/queue.module.js';
 import { FederationModule } from './federation/federation.module.js';
 import { ThrottlerGuard, ThrottlerModule } from '@nestjs/throttler';
+import { loadConfig } from '@mosaicstack/config';
+import { resolveGatewayConfigPath } from './env.js';
+
+// Federation (step-ca client, enrollment, federation verbs) is only wired for
+// tier 'federated' — CaService hard-requires STEP_CA_* at construction, which
+// must not gate standalone/local boots (docker-compose.federated.yml: the
+// federation profile "must not start in non-federated dev"). The gateway
+// entrypoint loads env.ts before evaluating this module so dotenv-backed tier
+// configuration is visible here.
+const federationEnabled = loadConfig(resolveGatewayConfigPath()).tier === 'federated';
 
 @Module({
   imports: [
@@ -53,7 +63,7 @@ import { ThrottlerGuard, ThrottlerModule } from '@nestjs/throttler';
     QueueModule,
     ReloadModule,
     WorkspaceModule,
-    FederationModule,
+    ...(federationEnabled ? [FederationModule] : []),
   ],
   controllers: [HealthController],
   providers: [
diff --git a/apps/gateway/src/config/config.module.ts b/apps/gateway/src/config/config.module.ts
index 5b65137a..d18cdd59 100644
--- a/apps/gateway/src/config/config.module.ts
+++ b/apps/gateway/src/config/config.module.ts
@@ -1,5 +1,6 @@
 import { Global, Module } from '@nestjs/common';
 import { loadConfig, type MosaicConfig } from '@mosaicstack/config';
+import { resolveGatewayConfigPath } from '../env.js';
 
 export const MOSAIC_CONFIG = 'MOSAIC_CONFIG';
 
@@ -8,7 +9,7 @@ export const MOSAIC_CONFIG = 'MOSAIC_CONFIG';
   providers: [
     {
       provide: MOSAIC_CONFIG,
-      useFactory: (): MosaicConfig => loadConfig(),
+      useFactory: (): MosaicConfig => loadConfig(resolveGatewayConfigPath()),
     },
   ],
   exports: [MOSAIC_CONFIG],
diff --git a/apps/gateway/src/env.ts b/apps/gateway/src/env.ts
new file mode 100644
index 00000000..4422343f
--- /dev/null
+++ b/apps/gateway/src/env.ts
@@ -0,0 +1,133 @@
+import { config } from 'dotenv';
+import { existsSync } from 'node:fs';
+import { homedir } from 'node:os';
+import { dirname, join, resolve } from 'node:path';
+import { fileURLToPath } from 'node:url';
+import { detectFromEnv, loadConfig } from '@mosaicstack/config';
+
+type TierSource =
+  | 'process environment'
+  | 'daemon .env'
+  | 'monorepo-root .env'
+  | 'gateway-local .env'
+  | 'default';
+
+type BootSource = TierSource | 'mosaic.config.json';
+
+export interface GatewayDotenvPaths {
+  daemonEnv: string;
+  monorepoRootEnv: string;
+  gatewayLocalEnv: string;
+}
+
+const here = dirname(fileURLToPath(import.meta.url));
+
+export function resolveGatewayDotenvPaths(
+  anchor: string = here,
+  homeBase: string = homedir(),
+): GatewayDotenvPaths {
+  return {
+    daemonEnv: join(homeBase, '.config', 'mosaic', 'gateway', '.env'),
+    monorepoRootEnv: resolve(anchor, '../../..', '.env'),
+    gatewayLocalEnv: resolve(anchor, '..', '.env'),
+  };
+}
+
+export function resolveGatewayConfigPath(anchor: string = here): string {
+  // GATEWAY_HOME is daemon-created 0700; its env override adds no authority because env can set MOSAIC_STORAGE_TIER.
+  const gatewayHome = resolve(
+    process.env['MOSAIC_GATEWAY_HOME'] ?? join(homedir(), '.config', 'mosaic', 'gateway'),
+  );
+  const daemonConfig = join(gatewayHome, 'mosaic.config.json');
+  const gatewayLocalConfig = resolve(anchor, '..', 'mosaic.config.json');
+  const monorepoRootConfig = resolve(anchor, '../../..', 'mosaic.config.json');
+
+  if (existsSync(daemonConfig)) {
+    return daemonConfig;
+  }
+  if (existsSync(gatewayLocalConfig)) {
+    return gatewayLocalConfig;
+  }
+  if (existsSync(monorepoRootConfig)) {
+    return monorepoRootConfig;
+  }
+
+  return monorepoRootConfig;
+}
+
+export function loadGatewayEnv(anchor: string = here, homeBase: string = homedir()): void {
+  const { daemonEnv, monorepoRootEnv, gatewayLocalEnv } = resolveGatewayDotenvPaths(
+    anchor,
+    homeBase,
+  );
+  const inheritedTier = process.env['MOSAIC_STORAGE_TIER'];
+  let tierSource: TierSource = inheritedTier === undefined ? 'default' : 'process environment';
+  const inheritedDatabaseUrl = process.env['DATABASE_URL'];
+  let databaseUrlSource: TierSource =
+    inheritedDatabaseUrl === undefined ? 'default' : 'process environment';
+
+  function loadAnchoredDotenv(
+    path: string,
+    sourceLabel: Exclude<TierSource, 'process environment' | 'default'>,
+  ): void {
+    if (!existsSync(path)) {
+      return;
+    }
+
+    const beforeTier = process.env['MOSAIC_STORAGE_TIER'];
+    const beforeDatabaseUrl = process.env['DATABASE_URL'];
+    config({ path, quiet: true });
+
+    if (
+      beforeTier === undefined &&
+      process.env['MOSAIC_STORAGE_TIER'] !== undefined &&
+      tierSource === 'default'
+    ) {
+      tierSource = sourceLabel;
+    }
+
+    if (
+      beforeDatabaseUrl === undefined &&
+      process.env['DATABASE_URL'] !== undefined &&
+      databaseUrlSource === 'default'
+    ) {
+      databaseUrlSource = sourceLabel;
+    }
+  }
+
+  // Load .env from daemon config dir (global install / daemon mode) first.
+  // It takes precedence over file-based local-dev configuration.
+  loadAnchoredDotenv(daemonEnv, 'daemon .env');
+
+  // Load .env from the anchored monorepo root, then fill any remaining values
+  // from apps/gateway/.env when present.
+  loadAnchoredDotenv(monorepoRootEnv, 'monorepo-root .env');
+  loadAnchoredDotenv(gatewayLocalEnv, 'gateway-local .env');
+
+  const envOnlyTier = detectFromEnv().tier;
+  const configPath = resolveGatewayConfigPath(anchor);
+  const anchoredConfigExists = existsSync(configPath);
+  const resolvedTier = loadConfig(configPath).tier;
+  const configuredTier = process.env['MOSAIC_STORAGE_TIER'];
+  const databaseUrlDeterminesTier = envOnlyTier === 'standalone' && configuredTier !== 'standalone';
+  const recognizedTierDeterminesTier =
+    (configuredTier === 'federated' ||
+      configuredTier === 'standalone' ||
+      configuredTier === 'local') &&
+    configuredTier === envOnlyTier;
+
+  let source: BootSource;
+  if (anchoredConfigExists) {
+    source = 'mosaic.config.json';
+  } else if (databaseUrlDeterminesTier && databaseUrlSource !== 'default') {
+    source = databaseUrlSource;
+  } else if (recognizedTierDeterminesTier && tierSource !== 'default') {
+    source = tierSource;
+  } else {
+    source = 'default';
+  }
+
+  console.info(`[gateway env] storage tier=${resolvedTier} source=${source}`);
+}
+
+loadGatewayEnv();
diff --git a/apps/gateway/src/main.spec.ts b/apps/gateway/src/main.spec.ts
new file mode 100644
index 00000000..10999917
--- /dev/null
+++ b/apps/gateway/src/main.spec.ts
@@ -0,0 +1,164 @@
+import 'reflect-metadata';
+import { mkdir, mkdtemp, rm, writeFile } from 'node:fs/promises';
+import * as nodeOs from 'node:os';
+import { dirname, isAbsolute, join, relative, resolve } from 'node:path';
+import * as nodeUrl from 'node:url';
+import type { MosaicConfig } from '@mosaicstack/config';
+import type * as MosaicStorage from '@mosaicstack/storage';
+import { describe, expect, it, vi, type MockInstance } from 'vitest';
+
+// Each case uses vi.resetModules() and re-imports the full gateway graph for distinct ambient FS/env; CI needs headroom, while this still guards genuine hangs.
+const MODULE_IMPORT_TIMEOUT_MS = 120_000;
+
+function snapshotProcessEnv(): Record<string, string | undefined> {
+  return { ...process.env };
+}
+
+function restoreProcessEnv(snapshot: Record<string, string | undefined>): void {
+  for (const key of Object.keys(process.env)) {
+    if (!(key in snapshot)) {
+      delete process.env[key];
+    }
+  }
+
+  for (const [key, value] of Object.entries(snapshot)) {
+    if (value === undefined) {
+      delete process.env[key];
+      continue;
+    }
+
+    process.env[key] = value;
+  }
+}
+
+function expectPathUnderTempRoot(path: string, tempRoot: string): void {
+  const relativePath = relative(tempRoot, path);
+  expect(relativePath === '' || (!relativePath.startsWith('..') && !isAbsolute(relativePath))).toBe(
+    true,
+  );
+}
+
+async function writeFixture(path: string, contents: string, tempRoot: string): Promise<void> {
+  expectPathUnderTempRoot(path, tempRoot);
+  await mkdir(dirname(path), { recursive: true });
+  await writeFile(path, contents, 'utf8');
+}
+
+interface BootstrapPreflightResult {
+  capturedConfig: MosaicConfig | undefined;
+}
+
+async function runBootstrapPreflight(
+  anchoredConfigContents: string,
+  ambientConfigContents: string,
+): Promise<BootstrapPreflightResult> {
+  const originalEnv = snapshotProcessEnv();
+  const tempRoot = await mkdtemp(join(nodeOs.tmpdir(), 'mosaic-gateway-main-preflight-'));
+  let cwdSpy: ReturnType<typeof vi.spyOn> | undefined;
+  let exitSpy: MockInstance<typeof process.exit> | undefined;
+  let consoleInfoSpy: ReturnType<typeof vi.spyOn> | undefined;
+  let capturedConfig: MosaicConfig | undefined;
+
+  try {
+    const anchor = join(tempRoot, 'anchored', 'apps', 'gateway', 'src');
+    const homePath = join(tempRoot, 'home');
+    const cwdPath = join(tempRoot, 'ambient', 'cwd');
+    const monorepoRootConfigPath = resolve(anchor, '../../..', 'mosaic.config.json');
+
+    await mkdir(anchor, { recursive: true });
+    await mkdir(cwdPath, { recursive: true });
+
+    await writeFixture(monorepoRootConfigPath, anchoredConfigContents, tempRoot);
+    await writeFixture(join(cwdPath, 'mosaic.config.json'), ambientConfigContents, tempRoot);
+
+    process.env['HOME'] = homePath;
+    process.env['BETTER_AUTH_SECRET'] = 'fixture-secret';
+    delete process.env['MOSAIC_STORAGE_TIER'];
+    delete process.env['DATABASE_URL'];
+    delete process.env['VALKEY_URL'];
+
+    consoleInfoSpy = vi.spyOn(console, 'info').mockImplementation((): void => undefined);
+    const exitMock = vi.fn<typeof process.exit>();
+    exitSpy = vi.spyOn(process, 'exit').mockImplementation(exitMock);
+
+    vi.resetModules();
+    vi.doMock('node:os', () => ({ ...nodeOs, homedir: (): string => homePath }));
+    vi.doMock('node:url', () => ({
+      ...nodeUrl,
+      fileURLToPath: (url: string | URL): string => {
+        const actualPath = nodeUrl.fileURLToPath(url);
+        if (
+          actualPath.endsWith('/apps/gateway/src/env.ts') ||
+          actualPath.endsWith('/apps/gateway/src/env.js')
+        ) {
+          return join(anchor, 'env.ts');
+        }
+        return actualPath;
+      },
+    }));
+    cwdSpy = vi.spyOn(process, 'cwd').mockReturnValue(cwdPath);
+    vi.doMock('./tracing.js', () => ({}));
+
+    const preflightSentinel = new Error('preflight-capture-sentinel');
+    vi.doMock('@mosaicstack/storage', async () => {
+      const actual = await vi.importActual<typeof MosaicStorage>('@mosaicstack/storage');
+      return {
+        ...actual,
+        detectAndAssertTier: vi.fn((config: MosaicConfig): Promise<void> => {
+          capturedConfig = config;
+          throw preflightSentinel;
+        }),
+      };
+    });
+
+    await import('./main.js');
+    await vi.waitFor((): void => {
+      expect(exitSpy).toHaveBeenCalled();
+    });
+
+    return { capturedConfig };
+  } finally {
+    cwdSpy?.mockRestore();
+    exitSpy?.mockRestore();
+    consoleInfoSpy?.mockRestore();
+    vi.doUnmock('@mosaicstack/storage');
+    vi.doUnmock('./tracing.js');
+    vi.doUnmock('node:url');
+    vi.doUnmock('node:os');
+    vi.resetModules();
+    restoreProcessEnv(originalEnv);
+    await rm(tempRoot, { recursive: true, force: true });
+  }
+}
+
+describe('main bootstrap preflight config anchoring', (): void => {
+  it(
+    'passes the anchored monorepo-root config to detectAndAssertTier, not an ambient cwd config',
+    async (): Promise<void> => {
+      const anchoredConfig = JSON.stringify({
+        tier: 'local',
+        storage: { type: 'pglite', dataDir: '.mosaic/storage-pglite' },
+        queue: { type: 'local', dataDir: '.mosaic/queue' },
+        memory: { type: 'keyword' },
+      });
+      const ambientConfig = JSON.stringify({
+        tier: 'federated',
+        storage: {
+          type: 'postgres',
+          url: 'postgresql://ambient-attacker.invalid/mosaic',
+          enableVector: true,
+        },
+        queue: { type: 'bullmq' },
+        memory: { type: 'pgvector' },
+      });
+
+      const { capturedConfig } = await runBootstrapPreflight(anchoredConfig, ambientConfig);
+
+      expect(capturedConfig?.tier).toBe('local');
+      expect(capturedConfig?.storage).not.toEqual(
+        expect.objectContaining({ url: 'postgresql://ambient-attacker.invalid/mosaic' }),
+      );
+    },
+    MODULE_IMPORT_TIMEOUT_MS,
+  );
+});
diff --git a/apps/gateway/src/main.ts b/apps/gateway/src/main.ts
index f70e88a4..d1eacf5f 100644
--- a/apps/gateway/src/main.ts
+++ b/apps/gateway/src/main.ts
@@ -1,18 +1,5 @@
 #!/usr/bin/env node
-import { config } from 'dotenv';
-import { existsSync } from 'node:fs';
-import { resolve, join } from 'node:path';
-import { homedir } from 'node:os';
-
-// Load .env from daemon config dir (global install / daemon mode).
-// Loaded first so monorepo .env can override for local dev.
-const daemonEnv = join(homedir(), '.config', 'mosaic', 'gateway', '.env');
-if (existsSync(daemonEnv)) config({ path: daemonEnv });
-
-// Load .env from monorepo root (cwd is apps/gateway when run via pnpm filter)
-config({ path: resolve(process.cwd(), '../../.env') });
-config(); // Also load apps/gateway/.env if present (overrides)
-
+import './env.js';
 import './tracing.js';
 import 'reflect-metadata';
 import { NestFactory } from '@nestjs/core';
@@ -26,6 +13,7 @@ import { mountAuthHandler } from './auth/auth.controller.js';
 import { mountMcpHandler } from './mcp/mcp.controller.js';
 import { McpService } from './mcp/mcp.service.js';
 import { detectAndAssertTier, TierDetectionError } from '@mosaicstack/storage';
+import { resolveGatewayConfigPath } from './env.js';
 
 async function bootstrap(): Promise<void> {
   const logger = new Logger('Bootstrap');
@@ -37,7 +25,7 @@ async function bootstrap(): Promise<void> {
   // Pre-flight: assert all external services required by the configured tier
   // are reachable. Runs before NestFactory.create() so failures are visible
   // immediately with actionable remediation hints.
-  const mosaicConfig = loadConfig();
+  const mosaicConfig = loadConfig(resolveGatewayConfigPath());
   try {
     await detectAndAssertTier(mosaicConfig);
   } catch (err) {