Five frontier models reportedly in the pipeline after Gemini 4 Argon
A roundup of rumored upcoming models: OpenAI Rosalind, Anthropic Fable 5.5 and Iggy, Grok 4.8, Meta Watermelon, and Google's internal Carbon.
Now that Gemini 4 Argon is out, here are the 5 leaked frontier models next in the pipeline: 1️⃣ OpenAI "Rosalind" → `gpt-rosalind-discovery` & `research` spotted on the API pricing page ($5 / $25 per 1M) 2️⃣ Anthropic Fable 5.5 & "Iggy" → Opus 5.5 users report silent routing tests + new "Iggy" agent & "Arborio" (Health) leaked in Claude Code UI 3️⃣ xAI Grok 4.8 → 2.5T parameter beast already sighted in Cursor’s model list 4️⃣ Meta "Watermelon" → Next frontier model targeting late October after Muse Wonder hit 79.0% on DeepSWE 5️⃣ Google Carbon → Already in employee testing on Jetski (`Argon → Barium → Carbon`) Which unreleased model are you watching closest?