diff --git a/apps/server-nestjs/src/modules/registry/registry-client.service.spec.ts b/apps/server-nestjs/src/modules/registry/registry-client.service.spec.ts
index 980c5335d5..c3958e5f40 100644
--- a/apps/server-nestjs/src/modules/registry/registry-client.service.spec.ts
+++ b/apps/server-nestjs/src/modules/registry/registry-client.service.spec.ts
@@ -1,4 +1,5 @@
 import type { ConfigType } from '@nestjs/config'
+import type { HarborRobot } from './registry-client.service'
 import { faker } from '@faker-js/faker'
 import { HttpStatus } from '@nestjs/common'
 import { Test } from '@nestjs/testing'
@@ -92,4 +93,112 @@ describe('registryService', () => {
 
     expect(res).toMatchObject({ status: HttpStatus.OK, data: { project_id: 123 } })
   })
+
+  describe('error and edge contracts', () => {
+    it('returns non-2xx statuses as data without throwing (caller-decides contract)', async () => {
+      server.use(
+        http.post(`${harborUrl}/api/v2.0/projects`, () =>
+          HttpResponse.json({ message: 'conflict: project name already exists' }, { status: HttpStatus.CONFLICT })),
+      )
+
+      const res = await service.createProject('myproj', -1)
+      expect(res.status).toBe(HttpStatus.CONFLICT)
+      expect(res.data).toMatchObject({ message: expect.stringContaining('already exists') })
+    })
+
+    it('propagates a 500 body through the caller-decides contract', async () => {
+      server.use(
+        http.get(`${harborUrl}/api/v2.0/projects/:projectName`, () =>
+          HttpResponse.json({ errors: [{ code: 'INTERNAL' }] }, { status: HttpStatus.INTERNAL_SERVER_ERROR })),
+      )
+
+      const res = await service.getProjectByName('myproj')
+      expect(res.status).toBe(HttpStatus.INTERNAL_SERVER_ERROR)
+    })
+
+    it('treats 204 No Content as null data', async () => {
+      server.use(
+        http.delete(`${harborUrl}/api/v2.0/projects/:projectName`, () => new Response(null, { status: HttpStatus.NO_CONTENT })),
+      )
+
+      const res = await service.deleteProjectByName('myproj')
+      expect(res).toEqual({ status: HttpStatus.NO_CONTENT, data: null })
+    })
+
+    it('falls back to text parsing when content-type is not JSON', async () => {
+      server.use(
+        http.get(`${harborUrl}/api/v2.0/quotas`, () =>
+          new Response('plain text error', { status: HttpStatus.OK, headers: { 'content-type': 'text/plain' } })),
+      )
+
+      const res = await service.listQuotas(123)
+      expect(res.data).toBe('plain text error')
+    })
+  })
+
+  describe('paginate', () => {
+    it('yields robots across pages until a short page ends iteration', async () => {
+      const seenPages: string[] = []
+      server.use(
+        http.get(`${harborUrl}/api/v2.0/robots`, ({ request }) => {
+          const page = Number(new URL(request.url).searchParams.get('page'))
+          seenPages.push(String(page))
+          // page size is ROBOT_LIST_PAGE_SIZE=100: full page → continue, short page → stop
+          const rows = page === 1
+            ? Array.from({ length: 100 }, (_, i) => ({ id: i + 1, name: `robot${i}` }))
+            : [{ id: 99, name: 'robot-last' }]
+          return HttpResponse.json(rows, { status: HttpStatus.OK })
+        }),
+      )
+
+      const robots: HarborRobot[] = []
+      for await (const robot of service.getProjectRobots(42)) robots.push(robot)
+
+      expect(seenPages).toEqual(['1', '2'])
+      expect(robots).toHaveLength(101)
+      expect(robots.at(-1)).toMatchObject({ id: 99 })
+    })
+
+    it('stops immediately on an empty first page', async () => {
+      let callCount = 0
+      server.use(
+        http.get(`${harborUrl}/api/v2.0/robots`, () => {
+          callCount++
+          return HttpResponse.json([], { status: HttpStatus.OK })
+        }),
+      )
+
+      const robots: HarborRobot[] = []
+      for await (const robot of service.getProjectRobots(42)) robots.push(robot)
+
+      expect(callCount).toBe(1)
+      expect(robots).toEqual([])
+    })
+  })
+
+  describe('getRetentionId', () => {
+    it('returns null when project lookup fails', async () => {
+      server.use(
+        http.get(`${harborUrl}/api/v2.0/projects/:projectName`, () =>
+          HttpResponse.json({}, { status: HttpStatus.NOT_FOUND })),
+      )
+      await expect(service.getRetentionId('ghost')).resolves.toBeNull()
+    })
+
+    it('returns null when retention_id is absent or NaN', async () => {
+      server.use(
+        http.get(`${harborUrl}/api/v2.0/projects/:projectName`, () =>
+          HttpResponse.json({ project_id: 1, metadata: {} }, { status: HttpStatus.OK })),
+      )
+      await expect(service.getRetentionId('myproj')).resolves.toBeNull()
+    })
+
+    it('returns the numeric retention id from metadata', async () => {
+      server.use(
+        http.get(`${harborUrl}/api/v2.0/projects/:projectName`, () =>
+          HttpResponse.json({ project_id: 1, metadata: { retention_id: '77' } }, { status: HttpStatus.OK })),
+      )
+      await expect(service.getRetentionId('myproj')).resolves.toBe(77)
+    })
+  })
 })