fix(gitlab): load MR reviewer choices from the paired server that owns the repo (#29917)

The runtime GitLab API answered listAssignableUsers with an empty list, so the reviewer picker
was always empty for a paired server's repo. Add an optional gitlab.listAssignableUsers RPC on the
host; a host that predates it answers method_not_found and the picker stays empty as before.

src/main/runtime/orca-runtime-test-mocks.spec.ts

@@ -220,6 +220,7 @@ export {
   listGitLabWorkItemsMock,
   listGitLabIssuesMock,
   listGitLabLabelsMock,
+  listGitLabAssignableUsersMock,
   listGitLabTodosMock,
   getGitLabProjectRefForRemoteMock,
   getGitLabWorkItemByProjectRefMock,

src/main/runtime/orca-runtime-test-mocks/setup.spec.ts

@@ -162,6 +162,7 @@ const {
   listGitLabWorkItemsMock,
   listGitLabIssuesMock,
   listGitLabLabelsMock,
+  listGitLabAssignableUsersMock,
   listGitLabTodosMock,
   getGitLabProjectRefForRemoteMock,
   getGitLabWorkItemByProjectRefMock,
@@ -248,6 +249,7 @@ const {
     listGitLabWorkItemsMock: vi.fn() as TestMock,
     listGitLabIssuesMock: vi.fn() as TestMock,
     listGitLabLabelsMock: vi.fn() as TestMock,
+    listGitLabAssignableUsersMock: vi.fn<TestMock>(),
     listGitLabTodosMock: vi.fn() as TestMock,
     getGitLabProjectRefForRemoteMock: vi.fn() as TestMock,
     getGitLabWorkItemByProjectRefMock: vi.fn() as TestMock,
@@ -440,6 +442,7 @@ vi.mock('../../gitlab/client', async (importOriginal) => {
     listWorkItems: listGitLabWorkItemsMock,
     listIssues: listGitLabIssuesMock,
     listLabels: listGitLabLabelsMock,
+    listAssignableUsers: listGitLabAssignableUsersMock,
     listTodos: listGitLabTodosMock,
     getProjectRefForRemote: getGitLabProjectRefForRemoteMock,
     getWorkItemByProjectRef: getGitLabWorkItemByProjectRefMock,
@@ -589,6 +592,7 @@ export {
   listGitLabWorkItemsMock,
   listGitLabIssuesMock,
   listGitLabLabelsMock,
+  listGitLabAssignableUsersMock,
   listGitLabTodosMock,
   getGitLabProjectRefForRemoteMock,
   getGitLabWorkItemByProjectRefMock,

src/main/runtime/orca-runtime-tests/gitlab-and-pr-bases.spec.ts

@@ -11,6 +11,7 @@ import {
   getGitLabWorkItemDetailsMock,
   listGitLabIssuesMock,
   listGitLabLabelsMock,
+  listGitLabAssignableUsersMock,
   listGitLabMergeRequestsMock,
   listGitLabTodosMock,
   listGitLabWorkItemsMock,
@@ -45,6 +46,7 @@ describe('OrcaRuntimeService', () => {
     })
     listGitLabTodosMock.mockResolvedValue([])
     listGitLabLabelsMock.mockResolvedValue(['bug', 'frontend'])
+    listGitLabAssignableUsersMock.mockResolvedValue([])
     getGitLabWorkItemByProjectRefMock.mockResolvedValue({
       id: 'gitlab-issue-7',
       type: 'issue',
@@ -89,6 +91,7 @@ describe('OrcaRuntimeService', () => {
     const issues = await runtime.listGitLabRepoIssues(TEST_REPO_ID, 'opened', '@me', 50, 3)
     await runtime.listGitLabRepoTodos(TEST_REPO_ID)
     await runtime.listGitLabRepoLabels(TEST_REPO_ID)
+    await runtime.listGitLabRepoAssignableUsers(TEST_REPO_ID)
     await runtime.createGitLabRepoIssue(TEST_REPO_ID, 'New issue', 'Body')
     await runtime.updateGitLabRepoIssue(TEST_REPO_ID, 7, { state: 'closed' })
     await runtime.addGitLabRepoIssueComment(TEST_REPO_ID, 7, 'Looks good')
@@ -162,6 +165,7 @@ describe('OrcaRuntimeService', () => {
     expect(issues).toMatchObject({ totalPages: 3 })
     expect(listGitLabTodosMock).toHaveBeenCalledWith('/remote/repo', 'ssh-1')
     expect(listGitLabLabelsMock).toHaveBeenCalledWith('/remote/repo', 'origin', 'ssh-1')
+    expect(listGitLabAssignableUsersMock).toHaveBeenCalledWith('/remote/repo', 'origin', 'ssh-1')
     expect(createGitLabIssueMock).toHaveBeenCalledWith(
       '/remote/repo',
       'New issue',

src/main/runtime/rpc/methods/gitlab.test.ts

@@ -10,6 +10,26 @@ function makeRequest(method: string, params?: unknown): RpcRequest {
 }
 
 describe('gitlab RPC methods', () => {
+  it("lists a repo's assignable users on the server that owns the repo", async () => {
+    const users = [
+      { id: 7, username: 'ana', name: 'Ana', avatarUrl: 'https://gitlab.example.com/ana.png' }
+    ]
+    const listGitLabRepoAssignableUsers = vi.fn().mockResolvedValue(users)
+    const runtime = { getRuntimeId: () => 'test-runtime', listGitLabRepoAssignableUsers }
+    const dispatcher = new RpcDispatcher({
+      // oxlint-disable-next-line typescript/consistent-type-assertions -- SAFETY: these methods dispatch only listGitLabRepoAssignableUsers.
+      runtime: runtime as unknown as OrcaRuntimeService,
+      methods: GITLAB_METHODS
+    })
+
+    const response = await dispatcher.dispatch(
+      makeRequest('gitlab.listAssignableUsers', { repo: 'id:repo-1' })
+    )
+
+    expect(listGitLabRepoAssignableUsers).toHaveBeenCalledWith('id:repo-1')
+    expect(response).toMatchObject({ ok: true, result: users })
+  })
+
   it('routes GitLab task queries and mutations to the runtime server', async () => {
     const runtime = {
       getRuntimeId: () => 'test-runtime',

src/main/runtime/rpc/methods/gitlab.ts

@@ -89,6 +89,12 @@ export const GITLAB_METHODS = [
     params: RepoSelector,
     handler: async (params, { runtime }) => runtime.listGitLabRepoLabels(params.repo)
   }),
+  defineMethod({
+    name: 'gitlab.listAssignableUsers',
+    permission: 'workspace',
+    params: RepoSelector,
+    handler: async (params, { runtime }) => runtime.listGitLabRepoAssignableUsers(params.repo)
+  }),
   defineMethod({
     name: 'gitlab.createIssue',
     permission: 'workspace',

src/main/runtime/runtime-gitlab-query-commands.ts

@@ -4,6 +4,7 @@ import {
   diagnoseAuth,
   getRateLimit,
   getWorkItemByProjectRef,
+  listAssignableUsers,
   listIssues,
   listLabels,
   listMergeRequests,
@@ -141,6 +142,18 @@ export class RuntimeGitLabQueryCommands {
     )
   }
 
+  async listGitLabRepoAssignableUsers(
+    repoSelector: string
+  ): Promise<Awaited<ReturnType<typeof listAssignableUsers>>> {
+    const repo = await this.deps.resolveRepo(repoSelector)
+    return listAssignableUsers(
+      repo.path,
+      repo.issueSourcePreference,
+      repo.connectionId ?? null,
+      ...this.deps.getLocalGitArgs(repo)
+    )
+  }
+
   async getGitLabRepoWorkItemDetails(
     repoSelector: string,
     iid: number,

src/main/runtime/runtime-review-command-surface.ts

@@ -68,6 +68,7 @@ export function installRuntimeReviewCommandSurface(
     diagnoseGitLabAuth: glq.diagnoseGitLabAuth.bind(glq),
     getGitLabRateLimit: glq.getGitLabRateLimit.bind(glq),
     listGitLabRepoLabels: glq.listGitLabRepoLabels.bind(glq),
+    listGitLabRepoAssignableUsers: glq.listGitLabRepoAssignableUsers.bind(glq),
     getGitLabRepoWorkItemDetails: glq.getGitLabRepoWorkItemDetails.bind(glq),
     getGitLabRepoWorkItemByPath: glq.getGitLabRepoWorkItemByPath.bind(glq),
     createGitLabRepoIssue: glm.createGitLabRepoIssue.bind(glm),

src/renderer/src/runtime/gitlab-owner-api.test.ts

@@ -37,6 +37,55 @@ describe('gitLabApiFor', () => {
     )
   })
 
+  it("loads a server-owned repo's reviewers from that server", async () => {
+    const reviewer = {
+      id: 7,
+      username: 'ana',
+      name: 'Ana',
+      avatarUrl: 'https://gitlab.example.com/ana.png'
+    }
+    rpc.call.mockResolvedValue([reviewer])
+    const selector = {
+      repoPath: '/work/app',
+      repoId: 'server-repo',
+      repoOwnerExecutionHostId: 'runtime:owner-server'
+    }
+
+    await expect(gitLabApiFor(selector).listAssignableUsers(selector)).resolves.toEqual([reviewer])
+    expect(rpc.call).toHaveBeenCalledWith(
+      { kind: 'environment', environmentId: 'owner-server' },
+      'gitlab.listAssignableUsers',
+      expect.objectContaining({ repo: 'id:server-repo' }),
+      { timeoutMs: 30_000 }
+    )
+  })
+
+  it('offers no reviewers from a server older than the reviewer RPC', async () => {
+    rpc.call.mockRejectedValue(
+      Object.assign(new Error('Unknown method'), { code: 'method_not_found' })
+    )
+    const selector = {
+      repoPath: '/work/app',
+      repoId: 'server-repo',
+      repoOwnerExecutionHostId: 'runtime:owner-server'
+    }
+
+    await expect(gitLabApiFor(selector).listAssignableUsers(selector)).resolves.toEqual([])
+  })
+
+  it('surfaces other reviewer lookup failures', async () => {
+    rpc.call.mockRejectedValue(Object.assign(new Error('glab failed'), { code: 'runtime_error' }))
+    const selector = {
+      repoPath: '/work/app',
+      repoId: 'server-repo',
+      repoOwnerExecutionHostId: 'runtime:owner-server'
+    }
+
+    await expect(gitLabApiFor(selector).listAssignableUsers(selector)).rejects.toThrow(
+      'glab failed'
+    )
+  })
+
   it.each(['ssh:devbox', 'local'])(
     'uses this computer for a %s repo',
     async (repoOwnerExecutionHostId) => {

src/renderer/src/runtime/runtime-gitlab-api.ts

@@ -9,6 +9,7 @@ import {
   type WebGitLabRuntimeMethod
 } from '@/web/preload-api/web-gitlab-routes'
 import { mapRepoPathArg } from './runtime-repo-selector-params'
+import { hasRuntimeRpcErrorCode } from './runtime-rpc-result'
 
 export type GitLabApi = NonNullable<PreloadApi['gl']>
 
@@ -46,7 +47,17 @@ export function createRuntimeGitLabApi(transport: RuntimeGitLabTransport): GitLa
       route<GitLabApiResult<'addIssueComment'>>(GITLAB_WEB_RPC_METHODS.addIssueComment, args),
     listLabels: (args) =>
       route<GitLabApiResult<'listLabels'>>(GITLAB_WEB_RPC_METHODS.listLabels, args),
-    listAssignableUsers: () => Promise.resolve([]),
+    // Why empty on method_not_found: a host older than this RPC simply offers no reviewers.
+    listAssignableUsers: (args) =>
+      route<GitLabApiResult<'listAssignableUsers'>>(
+        GITLAB_WEB_RPC_METHODS.listAssignableUsers,
+        args
+      ).catch((error: unknown) => {
+        if (hasRuntimeRpcErrorCode(error, 'method_not_found')) {
+          return []
+        }
+        throw error
+      }),
     todos: (args) => route<GitLabApiResult<'todos'>>(GITLAB_WEB_RPC_METHODS.todos, args),
     // Why: the owner guard names a host as this client sees it; the server resolves the repo itself.
     workItemDetails: ({ repoOwnerExecutionHostId: _owner, ...args }) =>

src/renderer/src/web/preload-api/web-gitlab-routes.ts

@@ -8,6 +8,7 @@ export type WebGitLabRouteKey =
   | 'updateIssue'
   | 'addIssueComment'
   | 'listLabels'
+  | 'listAssignableUsers'
   | 'todos'
   | 'workItemDetails'
   | 'closeMR'
@@ -32,6 +33,7 @@ export type WebGitLabRuntimeMethod =
   | 'gitlab.updateIssue'
   | 'gitlab.addIssueComment'
   | 'gitlab.listLabels'
+  | 'gitlab.listAssignableUsers'
   | 'gitlab.todos'
   | 'gitlab.workItemDetails'
   | 'gitlab.updateMRState'
@@ -55,6 +57,7 @@ export const GITLAB_WEB_RPC_METHODS = {
   updateIssue: 'gitlab.updateIssue',
   addIssueComment: 'gitlab.addIssueComment',
   listLabels: 'gitlab.listLabels',
+  listAssignableUsers: 'gitlab.listAssignableUsers',
   todos: 'gitlab.todos',
   workItemDetails: 'gitlab.workItemDetails',
   closeMR: 'gitlab.updateMRState',

src/renderer/src/web/web-preload-api-gitlab.test.ts

@@ -122,6 +122,12 @@ describe('web GitLab preload API', () => {
         expectedMethod: 'gitlab.listLabels',
         expectedParams: { repoPath, repo: repoPath }
       },
+      {
+        key: 'listAssignableUsers',
+        invoke: (gl) => gl.listAssignableUsers({ repoPath }),
+        expectedMethod: 'gitlab.listAssignableUsers',
+        expectedParams: { repoPath, repo: repoPath }
+      },
       {
         key: 'todos',
         invoke: (gl) => gl.todos({ repoPath }),

src/shared/rpc-contract/rpc-params-catalog.generated.ts

@@ -990,6 +990,7 @@ export const RPC_PARAMS_BY_METHOD = {
   'gitlab.createIssue': CreateIssueOfGitlabParams,
   'gitlab.diagnoseAuth': EmptyParams,
   'gitlab.jobTrace': JobTrace,
+  'gitlab.listAssignableUsers': RepoSelectorOfGitlabParams,
   'gitlab.listIssues': IssuesListOfGitlabParams,
   'gitlab.listLabels': RepoSelectorOfGitlabParams,
   'gitlab.listMRs': WorkItemsListOfGitlabParams,