🛰️ feat: Add GPT-5.5 + Frontier OpenAI Models, Drop Deprecated Defaults (#13636)

* 🛰️ feat: Add GPT-5.5 + Frontier OpenAI Models, Drop Deprecated Defaults

* 🛰️ fix: Address Codex Review on OpenAI Model Refresh

- Replace nonexistent gpt-5.5-chat-latest with the actual chat-latest
  alias; register its context window, output cap, pricing, and cache
  rates, and pin explicit rates for legacy gpt-5.x-chat-latest aliases
  so the new chat-latest key cannot out-match their cheaper pricing
- Add long-context premium tiers (>272K input) for gpt-5.5 and gpt-5.4
- Disable streaming for pro reasoning models (o1-pro, gpt-5.x-pro),
  which OpenAI does not support, with spec coverage

* 🛰️ fix: Address Codex Round-2 Review and CI Spec Failure

- Allow chat-latest through the official OpenAI fetched-model filter
- Export isProReasoningModel and drop unsupported sampling parameters
  for versioned pro models (gpt-5.4-pro, gpt-5.5-pro), which the
  versioned-model exemption previously let through
- Honor the pro-model streaming disable in both agent chat-completions
  routes, which decide SSE from model_parameters before llmConfig exists
- Update models.spec default-list assertions for the refreshed defaults
  and cover chat-latest filter retention

* 🛰️ fix: Address Codex Round-3 Review

- Convert max_tokens for chat-latest, which the gpt-[5-9] guard missed
- Drop snake_case sampling params (top_p, logit_bias, penalties) in the
  reasoning-model exclusion list so addParams-sourced values are removed
- Add createOpenAIAggregatorHandlers and wire them into the agent
  chat-completions service's non-streaming branch, which previously ran
  with no handlers and always returned an empty aggregated response

* 🛰️ ci: Fix Import Order Drift and Controller Spec Mock

- Sort type import first in service.spec.ts per import-order convention
- Register isProReasoningModel in the openai controller spec's
  @librechat/api mock factory, whose enumerated exports left the new
  helper undefined and broke the non-streaming flow under test

* 🛰️ chore: Trim Scope to Model Catalog Changes

Revert the OpenAI endpoint and agent handler changes (pro-model
streaming, sampling exclusions, non-streaming aggregation) — that
surface is moving out of LibreChat into the agents SDK and belongs
in its own change. Keep the model list, token windows, pricing, and
the fetched-model filter for chat-latest.

* 🛰️ fix: Correct GPT-5.4 Context Windows and Pro Long-Context Pricing

- Set gpt-5.4 and gpt-5.4-pro context to the documented 1,050,000
  window — 272K is the long-context pricing breakpoint, not the cap,
  and using it truncated prompts before they could reach that tier
- Add gpt-5.4-pro long-context premium rates ($60/$270 above 272K)
  per its model page; gpt-5.5-pro documents no long-context tier

* 🛰️ fix: Add gpt-5.4-nano and gpt-5.5-pro Long-Context Pricing

- Register gpt-5.4-nano ($0.20/$1.25, cached $0.02, 400K context) in
  the model list, pricing, cache, and token maps — the longest-match
  fallback billed it at gpt-5.4's $2.50/$15
- Add gpt-5.5-pro long-context premium rates ($60/$270 above 272K);
  the pricing table lists the tier even though the model page omits it

packages/api/src/utils/tokens.ts

@@ -55,10 +55,13 @@ const openAIModels = {
   'gpt-5.1': 400000,
   'gpt-5.2': 400000,
   'gpt-5.3': 400000,
-  'gpt-5.4': 272000, // standard context; 1M experimental available via API opt-in (2x rate)
-  'gpt-5.4-pro': 272000, // same window as gpt-5.4
+  'gpt-5.4': 1050000, // >272K input prices at the long-context tier (2x input, 1.5x output)
+  'gpt-5.4-pro': 1050000,
+  'gpt-5.4-mini': 400000,
+  'gpt-5.4-nano': 400000,
   'gpt-5.5': 1050000,
   'gpt-5.5-pro': 1050000,
+  'chat-latest': 400000,
   'gpt-5-mini': 400000,
   'gpt-5-nano': 400000,
   'gpt-5-pro': 400000,
@@ -383,8 +386,11 @@ export const modelMaxOutputs = {
   'gpt-5.3': 128000,
   'gpt-5.4': 128000,
   'gpt-5.4-pro': 128000,
+  'gpt-5.4-mini': 128000,
+  'gpt-5.4-nano': 128000,
   'gpt-5.5': 128000,
   'gpt-5.5-pro': 128000,
+  'chat-latest': 128000,
   'gpt-5-mini': 128000,
   'gpt-5-nano': 128000,
   'gpt-5-pro': 128000,