From 4cefa5cd883614765d864902753e38054b24a804 Mon Sep 17 00:00:00 2001
From: "shaggy (mosaic-dev box)" <shaggy@mosaic-dev.local>
Date: Tue, 11 Aug 2026 18:37:54 -0500
Subject: [PATCH] fix(gateway): resolve InteractionCoordinationService handoff
 factory via optional DI token (#1145)

root cause: emitDecoratorMetadata reflected the third constructor parameter as Function and Nest attempted to resolve it

fix: optional HANDOFF_ID_FACTORY injection token, no production provider, preserving undefined -> crypto.randomUUID() default and unchanged positional construction

TDD: real CoordModule red at Function index [2], then green; test overrides only unrelated AuthGuard because its AUTH provider comes from AppModule's global AuthModule context

Closes #1145
---
 .../coord/interaction-coordination.di.test.ts | 19 +++++++++++++++++++
 .../coord/interaction-coordination.service.ts |  5 ++++-
 2 files changed, 23 insertions(+), 1 deletion(-)
 create mode 100644 apps/gateway/src/coord/interaction-coordination.di.test.ts

diff --git a/apps/gateway/src/coord/interaction-coordination.di.test.ts b/apps/gateway/src/coord/interaction-coordination.di.test.ts
new file mode 100644
index 00000000..75b63e20
--- /dev/null
+++ b/apps/gateway/src/coord/interaction-coordination.di.test.ts
@@ -0,0 +1,19 @@
+import 'reflect-metadata';
+import { Test } from '@nestjs/testing';
+import { describe, expect, it } from 'vitest';
+import { CoordModule } from './coord.module.js';
+import { InteractionCoordinationService } from './interaction-coordination.service.js';
+import { AuthGuard } from '../auth/auth.guard.js';
+
+describe('CoordModule DI (compiled-metadata boot)', () => {
+  it('resolves InteractionCoordinationService through Nest DI', async () => {
+    const moduleRef = await Test.createTestingModule({ imports: [CoordModule] })
+      .overrideGuard(AuthGuard)
+      .useValue({ canActivate: (): boolean => true })
+      .compile();
+    expect(moduleRef.get(InteractionCoordinationService)).toBeInstanceOf(
+      InteractionCoordinationService,
+    );
+    await moduleRef.close();
+  });
+});
diff --git a/apps/gateway/src/coord/interaction-coordination.service.ts b/apps/gateway/src/coord/interaction-coordination.service.ts
index cf16e64a..a1035af9 100644
--- a/apps/gateway/src/coord/interaction-coordination.service.ts
+++ b/apps/gateway/src/coord/interaction-coordination.service.ts
@@ -1,4 +1,4 @@
-import { Inject, Injectable } from '@nestjs/common';
+import { Inject, Injectable, Optional } from '@nestjs/common';
 import {
   InteractionCoordinationClient,
   type CoordinationObservation,
@@ -13,6 +13,7 @@ import type { CreateHandoffDto } from './interaction-coordination.dto.js';
 
 export const COORDINATION_PORT = Symbol('COORDINATION_PORT');
 export const COORDINATION_CONFIG = Symbol('COORDINATION_CONFIG');
+export const HANDOFF_ID_FACTORY = Symbol('HANDOFF_ID_FACTORY');
 
 const HANDOFF_TRACKING_TTL_MS = 60 * 60 * 1_000;
 const MAX_TRACKED_HANDOFFS = 1_000;
@@ -60,6 +61,8 @@ export class InteractionCoordinationService {
   constructor(
     @Inject(COORDINATION_PORT) private readonly port: InteractionCoordinationPort,
     @Inject(COORDINATION_CONFIG) private readonly config: InteractionCoordinationConfig,
+    @Optional()
+    @Inject(HANDOFF_ID_FACTORY)
     private readonly handoffIdFactory: () => string = (): string => crypto.randomUUID(),
   ) {}