Add AGENTS selector for new threads

src/App.vue

@@ -525,6 +525,17 @@
                 <p v-if="newThreadCwd" class="new-thread-folder-selected" :title="newThreadCwd">
                   {{ t('Selected folder') }}: {{ newThreadCwd }}
                 </p>
+                <div v-if="newThreadAgentOptions.length > 1" class="new-thread-agents-select">
+                  <p class="new-thread-agents-select-label">{{ t('Instructions') }}</p>
+                  <ComposerDropdown
+                    class="new-thread-agents-dropdown"
+                    :model-value="selectedNewThreadAgentFile"
+                    :options="newThreadAgentDropdownOptions"
+                    :placeholder="t('Select instructions')"
+                    :disabled="isLoadingNewThreadAgents"
+                    @update:model-value="onSelectNewThreadAgentFile"
+                  />
+                </div>
                 <div class="new-thread-folder-actions">
                   <button class="new-thread-folder-action new-thread-folder-action-primary" type="button" @click="onOpenExistingFolder">
                     {{ t('Select folder') }}
@@ -874,6 +885,7 @@ import {
   getAccounts,
   createLocalDirectory,
   getFirstLaunchPluginsCardPreference,
+  getAgentInstructionsOptions,
   getHomeDirectory,
   getTelegramConfig,
   getProjectRootSuggestion,
@@ -890,7 +902,7 @@ import {
 } from './api/codexGateway'
 import type { ReasoningEffort, SpeedMode, ThreadScrollState, UiAccountEntry, UiRateLimitWindow, UiServerRequest, UiServerRequestReply, UiThreadTokenUsage } from './types/codex'
 import type { ComposerDraftPayload, ThreadComposerExposed } from './components/content/ThreadComposer.vue'
-import type { LocalDirectoryEntry, TelegramStatus, WorktreeBranchOption } from './api/codexGateway'
+import type { AgentInstructionsOption, LocalDirectoryEntry, TelegramStatus, WorktreeBranchOption } from './api/codexGateway'
 import { getFreeModeStatus, setFreeMode, setFreeModeCustomKey, setCustomProvider } from './api/codexGateway'
 import { getPathLeafName, getPathParent, isProjectlessChatPath, normalizePathForUi } from './pathUtils.js'
 
@@ -1133,6 +1145,9 @@ const newThreadRuntime = ref<'local' | 'worktree'>('local')
 const newWorktreeBaseBranch = ref('')
 const worktreeBranchOptions = ref<WorktreeBranchOption[]>([])
 const isLoadingWorktreeBranches = ref(false)
+const newThreadAgentOptions = ref<AgentInstructionsOption[]>([])
+const selectedNewThreadAgentFile = ref('project:AGENTS.md')
+const isLoadingNewThreadAgents = ref(false)
 const workspaceRootOptionsState = ref<{ order: string[]; labels: Record<string, string> }>({ order: [], labels: {} })
 const worktreeInitStatus = ref<{ phase: 'idle' | 'running' | 'error'; title: string; message: string }>({
   phase: 'idle',
@@ -1421,6 +1436,12 @@ const newWorktreeBranchDropdownOptions = computed<Array<{ value: string; label:
   }
   return options
 })
+const newThreadAgentDropdownOptions = computed<Array<{ value: string; label: string }>>(() =>
+  newThreadAgentOptions.value.map((option) => ({ value: option.value, label: option.label })),
+)
+const selectedNewThreadAgentOption = computed(() =>
+  newThreadAgentOptions.value.find((option) => option.value === selectedNewThreadAgentFile.value) ?? null,
+)
 const selectedWorktreeBranchLabel = computed(() => {
   const selectedBranch = newWorktreeBaseBranch.value.trim()
   if (!selectedBranch) return ''
@@ -2342,6 +2363,10 @@ function onSelectNewThreadFolder(cwd: string): void {
   createFolderError.value = ''
 }
 
+function onSelectNewThreadAgentFile(value: string): void {
+  selectedNewThreadAgentFile.value = value.trim() || 'project:AGENTS.md'
+}
+
 function onSelectNewWorktreeBranch(branch: string): void {
   newWorktreeBaseBranch.value = branch.trim()
 }
@@ -3332,10 +3357,32 @@ watch(
   () => newThreadCwd.value,
   () => {
     worktreeInitStatus.value = { phase: 'idle', title: '', message: '' }
+    void loadNewThreadAgentOptions()
     void refreshDefaultProjectName()
   },
 )
 
+async function loadNewThreadAgentOptions(): Promise<void> {
+  const cwd = newThreadCwd.value.trim()
+  selectedNewThreadAgentFile.value = 'project:AGENTS.md'
+  newThreadAgentOptions.value = []
+  if (!cwd) return
+
+  isLoadingNewThreadAgents.value = true
+  try {
+    const options = await getAgentInstructionsOptions(cwd)
+    newThreadAgentOptions.value = options
+    if (!options.some((option) => option.value === selectedNewThreadAgentFile.value)) {
+      selectedNewThreadAgentFile.value = options[0]?.value ?? 'project:AGENTS.md'
+    }
+  } catch {
+    newThreadAgentOptions.value = []
+    selectedNewThreadAgentFile.value = 'project:AGENTS.md'
+  } finally {
+    isLoadingNewThreadAgents.value = false
+  }
+}
+
 watch(
   () => [newThreadRuntime.value, newThreadCwd.value] as const,
   ([runtime, cwd]) => {
@@ -3445,7 +3492,9 @@ async function submitFirstMessageForNewThread(
       targetCwd = directory.cwd
       newThreadCwd.value = directory.cwd
     }
-    const threadId = await sendMessageToNewThread(text, targetCwd, imageUrls, skills, fileAttachments)
+    const selectedAgent = selectedNewThreadAgentOption.value
+    const baseInstructions = selectedAgent && !selectedAgent.isDefault ? selectedAgent.content : undefined
+    const threadId = await sendMessageToNewThread(text, targetCwd, imageUrls, skills, fileAttachments, baseInstructions)
     if (!threadId) return
     await router.replace({ name: 'thread', params: { threadId } })
     scheduleMobileConversationJumpToLatest()
@@ -3750,6 +3799,22 @@ async function loadWorktreeBranches(sourceCwd: string): Promise<void> {
   @apply mt-2 mb-0 max-w-3xl text-center text-xs text-zinc-500 break-all;
 }
 
+.new-thread-agents-select {
+  @apply mt-3 w-full max-w-3xl;
+}
+
+.new-thread-agents-select-label {
+  @apply m-0 mb-1 text-xs font-medium uppercase tracking-wide text-zinc-500;
+}
+
+.new-thread-agents-dropdown :deep(.composer-dropdown-trigger) {
+  @apply h-9 rounded-xl border border-zinc-200 bg-white px-3 text-sm text-zinc-700;
+}
+
+:global(:root.dark) .new-thread-agents-select-label {
+  @apply text-zinc-500;
+}
+
 .new-thread-folder-actions {
   @apply mt-3 flex w-full max-w-3xl flex-wrap items-center justify-center gap-2;
 }

src/api/codexGateway.test.ts

@@ -1,23 +1,22 @@
 import { afterEach, describe, expect, it, vi } from 'vitest'
-import { startThreadTurn } from './codexGateway'
+import { getAgentInstructionsOptions, startThread, startThreadTurn } from './codexGateway'
 
-function mockRpcFetch(): { requests: Array<{ method: string, params: Record<string, unknown> }> } {
-  const requests: Array<{ method: string, params: Record<string, unknown> }> = []
+function mockRpcFetch(): { requests: Array<{ method: string, params: Record<string, unknown>, url: string }> } {
+  const requests: Array<{ method: string, params: Record<string, unknown>, url: string }> = []
 
   vi.stubGlobal('fetch', vi.fn(async (_input: RequestInfo | URL, init?: RequestInit) => {
+    const url = String(_input)
     const body = typeof init?.body === 'string'
-      ? JSON.parse(init.body) as { method: string, params: Record<string, unknown> }
+      ? JSON.parse(init.body) as { method: string, params: Record<string, unknown>, model?: unknown, baseInstructions?: unknown }
       : { method: '', params: {} }
 
-    requests.push(body)
+    requests.push({ ...body, url })
 
-    return new Response(JSON.stringify({
-      result: {
-        turn: {
-          id: `turn-${requests.length}`,
-        },
-      },
-    }), {
+    const result = url.includes('/codex-api/thread/start-with-agent-instructions') || body.method === 'thread/start'
+      ? { thread: { id: `thread-${requests.length}` }, model: body.params?.model ?? body.model ?? '' }
+      : { turn: { id: `turn-${requests.length}` } }
+
+    return new Response(JSON.stringify({ result }), {
       status: 200,
       headers: {
         'Content-Type': 'application/json',
@@ -28,6 +27,95 @@ function mockRpcFetch(): { requests: Array<{ method: string, params: Record<stri
   return { requests }
 }
 
+describe('startThread instruction payloads', () => {
+  afterEach(() => {
+    vi.unstubAllGlobals()
+  })
+
+  it('omits baseInstructions for the default AGENTS.md selection', async () => {
+    const { requests } = mockRpcFetch()
+
+    await startThread('/tmp/TestChat', 'gpt-5.4')
+
+    expect(requests).toHaveLength(1)
+    expect(requests[0].method).toBe('thread/start')
+    expect(requests[0].params).toEqual({
+      cwd: '/tmp/TestChat',
+      model: 'gpt-5.4',
+    })
+  })
+
+  it('sends only the selected custom agent instructions as baseInstructions', async () => {
+    const { requests } = mockRpcFetch()
+
+    await startThread('/tmp/TestChat', 'gpt-5.4', 'CUSTOM_AGENT_ONLY', { deferCwdUntilTurn: true })
+
+    expect(requests).toHaveLength(1)
+    expect(requests[0].url).toBe('/codex-api/thread/start-with-agent-instructions')
+    expect(requests[0]).toMatchObject({
+      cwd: '/tmp/TestChat',
+      model: 'gpt-5.4',
+      baseInstructions: 'CUSTOM_AGENT_ONLY',
+    })
+    expect(JSON.stringify(requests[0])).not.toContain('ORIGINAL_AGENTS_MARKER')
+  })
+})
+
+describe('getAgentInstructionsOptions', () => {
+  afterEach(() => {
+    vi.unstubAllGlobals()
+  })
+
+  it('preserves project and global instruction scopes', async () => {
+    vi.stubGlobal('fetch', vi.fn(async () => new Response(JSON.stringify({
+      data: [
+        {
+          value: 'project:AGENTS.md',
+          label: 'Default AGENTS.md',
+          path: '/tmp/TestChat/AGENTS.md',
+          content: 'ORIGINAL_AGENTS_MARKER',
+          isDefault: true,
+          scope: 'project',
+        },
+        {
+          value: 'global:AGENTS.review.md',
+          label: 'Global: AGENTS.review.md',
+          path: '/Users/igor/.codex/AGENTS.review.md',
+          content: 'GLOBAL_REVIEW_MARKER',
+          isDefault: false,
+          scope: 'global',
+        },
+      ],
+    }), {
+      status: 200,
+      headers: {
+        'Content-Type': 'application/json',
+      },
+    })))
+
+    const options = await getAgentInstructionsOptions('/tmp/TestChat')
+
+    expect(options).toEqual([
+      {
+        value: 'project:AGENTS.md',
+        label: 'Default AGENTS.md',
+        path: '/tmp/TestChat/AGENTS.md',
+        content: 'ORIGINAL_AGENTS_MARKER',
+        isDefault: true,
+        scope: 'project',
+      },
+      {
+        value: 'global:AGENTS.review.md',
+        label: 'Global: AGENTS.review.md',
+        path: '/Users/igor/.codex/AGENTS.review.md',
+        content: 'GLOBAL_REVIEW_MARKER',
+        isDefault: false,
+        scope: 'global',
+      },
+    ])
+  })
+})
+
 describe('startThreadTurn collaboration mode payloads', () => {
   afterEach(() => {
     vi.unstubAllGlobals()