fix: improve type safety in follow.ts by removing any usages (#550) (#575)

* fix: remove any usages in follow.ts, reuse Fastify/JWT types (#550)

* fix: type jwtVerify payload with AuthenticatedUser

* fix: add explicit return type and rename unused catch variable for ESLint

Author: yachikadev

apps/backend/src/routes/follow.ts

@@ -1,16 +1,19 @@
-import type { FastifyInstance, FastifyRequest, FastifyReply } from 'fastify';
+import { getPlatform, getProfileUrl, getWebViewUrl } from '@devcard/shared';
+
 import { decrypt } from '../utils/encryption.js';
 import { getErrorMessage } from '../utils/error.util.js';
-import { getPlatform, getProfileUrl, getWebViewUrl } from '@devcard/shared';
 import { followLogSchema } from '../validations/follow.validation.js';
 
-export async function followRoutes(app: FastifyInstance) {
+import type { AuthenticatedUser } from '../types/fastify.js';
+import type { FastifyInstance, FastifyRequest, FastifyReply } from 'fastify';
+
+export async function followRoutes(app: FastifyInstance): Promise<void> {
     app.addHook('preHandler', async (request, reply) => {
-      const server = request.server as any;
-      if (typeof server?.authenticate === 'function') { await server.authenticate(request, reply); return }
-      if (typeof (app as any).authenticate === 'function') { await (app as any).authenticate(request, reply); return }
-      try { const payload = await request.jwtVerify(); if (payload) (request as any).user = payload; } catch (e) { reply.status(401).send({ error: 'Unauthorized' }) }
-    });
+    const server = request.server;
+    if (typeof server?.authenticate === 'function') { await server.authenticate(request, reply); return }
+    if (typeof app.authenticate === 'function') { await app.authenticate(request, reply); return }
+    try { const payload = await request.jwtVerify<AuthenticatedUser>(); if (payload) {request.user = payload;} } catch (_e) { reply.status(401).send({ error: 'Unauthorized' }) }
+  });
 
   // ─── Follow via API (Layer 1) ───
   // Currently supports: GitHub
@@ -19,7 +22,7 @@ export async function followRoutes(app: FastifyInstance) {
     request: FastifyRequest<{ Params: { platform: string; targetUsername: string } }>,
     reply: FastifyReply
   ) => {
-    const userId = (request.user as any).id;
+    const userId = request.user.id;
     const { platform, targetUsername } = request.params;
 
     // GitHub follow tokens are stored under 'github_follow' to prevent the
@@ -116,7 +119,7 @@ export async function followRoutes(app: FastifyInstance) {
     }>,
     reply: FastifyReply
   ) => {
-    const userId = (request.user as any).id;
+    const userId = request.user.id;
     const { platform, targetUsername } = request.params;
 
     const parsed = followLogSchema.safeParse(request.body);
@@ -137,8 +140,8 @@ export async function followRoutes(app: FastifyInstance) {
         },
       });
       return reply.send({ status: 'success', logId: log.id });
-    } catch (error: any) {
-      app.log.error('Failed to log follow:', error);
+    } catch (error) {
+      app.log.error(`Failed to log follow: ${getErrorMessage(error)}`);
       return reply.status(500).send({ error: 'Failed to log follow event' });
     }
   });
@@ -148,7 +151,7 @@ export async function followRoutes(app: FastifyInstance) {
     request: FastifyRequest<{ Params: { platform: string; targetUsername: string } }>,
     reply: FastifyReply
   ) => {
-    const userId = (request.user as any).id;
+    const userId = request.user.id;
     const { platform, targetUsername } = request.params;
 
     await app.prisma.followLog.deleteMany({