apps/gateway/src/app.module.spec.ts

@@ -12,6 +12,7 @@ interface ComposedModuleGraph {
   federationModule: unknown;
   bootLogLines: readonly string[];
   mosaicConfig: MosaicConfig;
+  resolvedConfigPath: string;
 }
 
 type StorageTier = 'local' | 'standalone' | 'federated';
@@ -205,6 +206,7 @@ async function loadModuleGraphFromDotenv(
     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);
 
@@ -235,7 +237,7 @@ async function loadModuleGraphFromDotenv(
       expect(process.env['MOSAIC_STORAGE_TIER']).toBe(options.inheritedTier);
     }
 
-    await import('./env.js');
+    const envModule = await import('./env.js');
     expect(process.env['MOSAIC_STORAGE_TIER']).toBe(
       options.expectedProcessTier ?? options.rootTier,
     );
@@ -270,6 +272,7 @@ async function loadModuleGraphFromDotenv(
         args.map((value: unknown): string => String(value)).join(' '),
       ),
       mosaicConfig: configProvider.useFactory(),
+      resolvedConfigPath: envModule.resolveGatewayConfigPath(),
     };
   } finally {
     cwdSpy?.mockRestore();
@@ -360,20 +363,53 @@ describe('AppModule federation gating', (): void => {
   );
 
   it(
-    'anchored monorepo-root config wins gateway-local config and registers FederationModule',
+    '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.monorepoRootConfigPath,
+            fixture.gatewayLocalConfigPath,
             configJson('federated'),
             fixture.tempRoot,
           );
-          await writeFixture(fixture.gatewayLocalConfigPath, configJson('local'), 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');
     },

apps/gateway/src/env.ts

@@ -34,15 +34,23 @@ export function resolveGatewayDotenvPaths(
 }
 
 export function resolveGatewayConfigPath(anchor: string = here): string {
-  const monorepoRootConfig = resolve(anchor, '../../..', 'mosaic.config.json');
+  // 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(monorepoRootConfig)) {
-    return monorepoRootConfig;
+  if (existsSync(daemonConfig)) {
+    return daemonConfig;
   }
   if (existsSync(gatewayLocalConfig)) {
     return gatewayLocalConfig;
   }
+  if (existsSync(monorepoRootConfig)) {
+    return monorepoRootConfig;
+  }
 
   return monorepoRootConfig;
 }