Add OpenAI chat-latest support and generalize token handling

Add the chat-latest OpenAI API preset.

Broaden the OpenAI token-parameter helper naming so chat-latest can
share the max_completion_tokens path with GPT-5 latest models.

Reference:
- https://developers.openai.com/api/docs/models/chat-latest

Author: PeterDaveHello

src/config/index.mjs

@@ -50,6 +50,7 @@ export const chatgptApiModelKeys = [
   'chatgptApi35_1106',
   'chatgptApi35_0125',
   'chatgptApi4o_128k',
+  'chatgptApiChatLatest',
   'chatgptApi5Latest',
   'chatgptApi5',
   'chatgptApi5_1Latest',
@@ -255,6 +256,7 @@ export const Models = {
     value: 'gpt-4-0125-preview',
     desc: 'OpenAI (GPT-4-Turbo 128k 0125 Preview)',
   },
+  chatgptApiChatLatest: { value: 'chat-latest', desc: 'OpenAI (Chat latest)' },
   chatgptApi5Latest: { value: 'gpt-5-chat-latest', desc: 'OpenAI (GPT-5 latest)' },
   chatgptApi5: { value: 'gpt-5', desc: 'OpenAI (GPT-5)' },
   chatgptApi5_1Latest: { value: 'gpt-5.1-chat-latest', desc: 'OpenAI (GPT-5.1 latest)' },

src/services/apis/openai-token-params.mjs

@@ -1,12 +1,12 @@
-const GPT5_CHAT_COMPLETIONS_MODEL_PATTERN = /^gpt-5([.-]|$)/
+const OPENAI_MAX_COMPLETION_TOKENS_MODEL_PATTERN = /^(?:gpt-5(?:[.-]|$)|chat-latest$)/
 
 function shouldUseMaxCompletionTokens(provider, model) {
   const normalizedProvider = String(provider || '').toLowerCase()
   const normalizedModel = String(model || '').toLowerCase()
 
   switch (true) {
     case normalizedProvider === 'openai' &&
-      GPT5_CHAT_COMPLETIONS_MODEL_PATTERN.test(normalizedModel):
+      OPENAI_MAX_COMPLETION_TOKENS_MODEL_PATTERN.test(normalizedModel):
       return true
     default:
       return false

tests/unit/services/apis/openai-api-compat.test.mjs

@@ -8,13 +8,15 @@ import {
 import { createFakePort } from '../../helpers/port.mjs'
 import { createMockSseResponse } from '../../helpers/sse-response.mjs'
 
-const gpt5LatestCompatModelNames = [
+const latestCompatModelNames = [
+  'chatgptApi-chat-latest',
   'chatgptApi-gpt-5-chat-latest',
   'chatgptApi-gpt-5.1-chat-latest',
   'chatgptApi-gpt-5.2-chat-latest',
   'chatgptApi-gpt-5.3-chat-latest',
 ]
-const gpt5LatestMappedModels = [
+const latestMappedModels = [
+  ['chatgptApiChatLatest', 'chat-latest'],
   ['chatgptApi5Latest', 'gpt-5-chat-latest'],
   ['chatgptApi5_1Latest', 'gpt-5.1-chat-latest'],
   ['chatgptApi5_2Latest', 'gpt-5.2-chat-latest'],
@@ -93,7 +95,7 @@ test('generateAnswersWithOpenAiApiCompat sends expected request and aggregates S
   assert.deepEqual(session.conversationRecords.at(-1), { question: 'CurrentQ', answer: 'Hello' })
 })
 
-test('generateAnswersWithOpenAiApiCompat uses max_completion_tokens for OpenAI latest gpt-5 compat models', async (t) => {
+test('generateAnswersWithOpenAiApiCompat uses max_completion_tokens for OpenAI latest compat models', async (t) => {
   t.mock.method(console, 'debug', () => {})
   setStorage({
     maxConversationContextLength: 3,
@@ -108,7 +110,7 @@ test('generateAnswersWithOpenAiApiCompat uses max_completion_tokens for OpenAI l
     ])
   })
 
-  for (const modelName of gpt5LatestCompatModelNames) {
+  for (const modelName of latestCompatModelNames) {
     capturedInit = undefined
     const session = {
       modelName,
@@ -133,7 +135,7 @@ test('generateAnswersWithOpenAiApiCompat uses max_completion_tokens for OpenAI l
   }
 })
 
-test('generateAnswersWithOpenAiApiCompat uses latest mapped gpt-5 API model values', async (t) => {
+test('generateAnswersWithOpenAiApiCompat uses latest mapped API model values', async (t) => {
   t.mock.method(console, 'debug', () => {})
   setStorage({
     maxConversationContextLength: 3,
@@ -148,7 +150,7 @@ test('generateAnswersWithOpenAiApiCompat uses latest mapped gpt-5 API model valu
     ])
   })
 
-  for (const [modelName, expectedModel] of gpt5LatestMappedModels) {
+  for (const [modelName, expectedModel] of latestMappedModels) {
     capturedInit = undefined
     const session = {
       modelName,
@@ -279,7 +281,7 @@ test('generateAnswersWithOpenAiApi uses max_completion_tokens for GPT-5.4 nano',
   assert.equal(Object.hasOwn(body, 'max_tokens'), false)
 })
 
-test('generateAnswersWithOpenAiApiCompat keeps max_tokens for latest mapped gpt-5 models in compat provider', async (t) => {
+test('generateAnswersWithOpenAiApiCompat keeps max_tokens for latest mapped models in compat provider', async (t) => {
   t.mock.method(console, 'debug', () => {})
   setStorage({
     maxConversationContextLength: 3,
@@ -294,7 +296,7 @@ test('generateAnswersWithOpenAiApiCompat keeps max_tokens for latest mapped gpt-
     ])
   })
 
-  for (const [modelName, expectedModel] of gpt5LatestMappedModels) {
+  for (const [modelName, expectedModel] of latestMappedModels) {
     capturedInit = undefined
     const session = {
       modelName,
@@ -361,7 +363,7 @@ test('generateAnswersWithOpenAiApiCompat removes conflicting token key from extr
   assert.equal(body.top_p, 0.9)
 })
 
-test('generateAnswersWithOpenAiApiCompat removes max_tokens from extraBody for OpenAI gpt-5 models', async (t) => {
+test('generateAnswersWithOpenAiApiCompat removes max_tokens from extraBody for OpenAI latest models', async (t) => {
   t.mock.method(console, 'debug', () => {})
   setStorage({
     maxConversationContextLength: 3,
@@ -376,7 +378,7 @@ test('generateAnswersWithOpenAiApiCompat removes max_tokens from extraBody for O
     ])
   })
 
-  for (const modelName of gpt5LatestCompatModelNames) {
+  for (const modelName of latestCompatModelNames) {
     capturedInit = undefined
     const session = {
       modelName,
@@ -446,7 +448,7 @@ test('generateAnswersWithOpenAiApiCompat allows max_tokens override for compat p
   assert.equal(body.top_p, 0.75)
 })
 
-test('generateAnswersWithOpenAiApiCompat allows max_completion_tokens override for OpenAI gpt-5 models', async (t) => {
+test('generateAnswersWithOpenAiApiCompat allows max_completion_tokens override for OpenAI latest models', async (t) => {
   t.mock.method(console, 'debug', () => {})
   setStorage({
     maxConversationContextLength: 3,
@@ -461,7 +463,7 @@ test('generateAnswersWithOpenAiApiCompat allows max_completion_tokens override f
     ])
   })
 
-  for (const modelName of gpt5LatestCompatModelNames) {
+  for (const modelName of latestCompatModelNames) {
     capturedInit = undefined
     const session = {
       modelName,

tests/unit/services/apis/openai-token-params.test.mjs

@@ -8,6 +8,12 @@ test('uses max_completion_tokens for gpt-5.x chat models', () => {
   })
 })
 
+test('uses max_completion_tokens for chat-latest model', () => {
+  assert.deepEqual(getChatCompletionsTokenParams('openai', 'chat-latest', 1025), {
+    max_completion_tokens: 1025,
+  })
+})
+
 test('uses max_tokens for provider-prefixed gpt-5.x model names', () => {
   assert.deepEqual(getChatCompletionsTokenParams('openai', 'openai/gpt-5.2', 2048), {
     max_tokens: 2048,
@@ -50,6 +56,9 @@ test('uses max_tokens for lookalike model names', () => {
   assert.deepEqual(getChatCompletionsTokenParams('openai', 'my-gpt-5-clone', 640), {
     max_tokens: 640,
   })
+  assert.deepEqual(getChatCompletionsTokenParams('openai', 'my-chat-latest', 641), {
+    max_tokens: 641,
+  })
 })
 
 test('uses max_tokens for empty model values', () => {

tests/unit/utils/model-name-convert.test.mjs

@@ -258,6 +258,7 @@ test('modelNameToValue returns value for known model', () => {
 })
 
 test('modelNameToValue returns endpoint for latest chatgptApi models', () => {
+  assert.equal(modelNameToValue('chatgptApiChatLatest'), 'chat-latest')
   assert.equal(modelNameToValue('chatgptApi5Latest'), 'gpt-5-chat-latest')
   assert.equal(modelNameToValue('chatgptApi5_1Latest'), 'gpt-5.1-chat-latest')
   assert.equal(modelNameToValue('chatgptApi5_2Latest'), 'gpt-5.2-chat-latest')