Claude Opus 5.5 vs Grok 4.7 vs GPT-6 Sol: which coding agent model should you pick?
Three frontier coding models landed in about 48 hours. If you're shipping Next.js, Expo, and Supabase apps with Buildcamp's three agents, you need a clear pick, not another leaderboard screenshot.
The models:
- Claude Opus 5.5 (22 Sep 2026): Claude Code / API, also on Vercel AI Gateway as
anthropic/claude-opus-5.5 - Grok 4.7 (21 Sep 2026): Cursor's most capable model for long-running coding and knowledge work
- GPT-6 Sol (22 Sep 2026 on AI Gateway): Codex / Vercel AI Gateway as `openai/gpt-6-sol, with Luna as the cheaper high-volume sibling
They're not interchangeable. They live in different agents, price differently, and shine on different kinds of sessions. This guide compares them in plain English so you can choose for real product work.
How to read this (agents vs models)
In Buildcamp you mainly work inside three coding agents:
| Agent | Model you'll reach for here |
|---|---|
| Claude Code | Claude Opus 5.5 |
| Cursor | Grok 4.7 (Composer still for everyday speed) |
| Codex (ChatGPT / AI Gateway) | GPT-6 Sol, or Luna when volume matters |
A model is the brain. An agent is the harness: tools, diffs, terminals, and how long a session can stay useful. Pick the model that fits the job and the agent you already use well.
TL;DR: Which one should you pick?
| If you need... | Pick |
|---|---|
| Long migrations, sprawling refactors, a clear collaborator over hours | Claude Opus 5.5 in Claude Code |
| Hard multi-hour Cursor sessions with effort dials and big context | Grok 4.7 in Cursor |
| Sustained Codex coding where quality+iteration both matter | GPT-6 Sol via Codex / AI Gateway |
| Cheaper high-volume agentic / everyday Codex runs | GPT-6 Luna |
| Everyday Cursor speed and cost | Composer (keep Grok 4.7 for the hard jobs) |
| Lowest list $/M among these three frontiers | Grok 4.7 (or Luna if you're on OpenAI) |
| Paying up for an older high tier when Sol isn't enough | Consider GPT-6 Astra |
Short version: Use Opus 5.5 in Claude Code for the heaviest long agentic coding. Use Grok 4.7 in Cursor when the session is hard and long. Use Sol in Codex when you want GPT-6 quality with room to iterate, and Luna when you are burning lots of tokens on everyday agent work. Be honest about price: Opus is the premium list price of the three; Grok and Luna usually win on raw $/M.
Side-by-side on the honest axes
Pricing is a shape-of-costs snapshot (as of 22-23 Sep 2026). Always confirm live pages before you commit budget.
| Axis | Claude Opus 5.5 | Grok 4.7 (Cursor) | GPT-6 Sol (and Luna) |
|---|---|---|---|
| Where it lives | Claude Code, Claude API, AI Gateway (anthropic/claude-opus-5.5) | Cursor (Models pool with 4.6 / Composer) | Codex+AI Gateway (openai/gpt-6-sol, openai/gpt-6-luna) |
| List rates (per 1M tokens) | Input $4 / output $20; cache reads $0.20. Fast mode $8 / $40 | On-demand same as 4.6: $2 / $0.50 cached / $6. Fast $4 / $1 / $12 | Sol $2 / $10 (cached input $0.20). Luna $0.10 / $0.50 (cached $0.01) |
| Long agentic coding | Excellent: migrations, audits, overnight-style runs; strong collaborator over long sessions | Cursor's most capable for long-running coding and knowledge work; stronger self-verification than 4.6 | Sol aimed at complex professional workflows and sustained coding; Luna for high-volume agentic / everyday |
| Speed | ~30%+faster output than Opus 5; Fast mode up to ~2.5x at higher token prices | Fast tier at 2x rates; Composer still the everyday/fast pick | Depends on Gateway / Codex settings; Luna is the throughput play |
| Effort / thinking controls | Adaptive thinking always on; forced tool use retired | Effort: low, medium, high (default), xhigh | Configurable reasoning effort on Sol / Luna (see OpenAI / Gateway docs) |
| Context notes | Strong on long coding jobs; check Claude Platform docs for account-specific thinking/preservation rules | 256k standard, 500k long context; rates rise above 256k input | Large Gateway context windows (Sol/Luna listed around 1.05M on AI Gateway model pages); long prompts may use higher rates |
| Price honesty | ~40% cheaper than Opus 5 on typical workloads, but still the premium of these three on list $/M | Usually the cheapest frontier here for Cursor on-demand | Sol undercuts Astra; Luna undercuts almost everything for volume |
Sources for the numbers: Anthropic Opus 5.5, Vercel Opus 5.5 on Gateway, Cursor Grok 4.7, Cursor Grok 4.7 help, Vercel Sol & Luna, Gateway Sol, Gateway Luna, OpenAI Sol, OpenAI Luna.
Claude Opus 5.5 (Claude Code / API)
Released 22 Sep 2026. Anthropic positions Opus 5.5 as the first model in the Claude 5.5 family: frontier agentic coding and knowledge work at roughly 40% lower cost than Opus 5 on typical workloads, with ~30%+faster output.
Strengths
- Long, sprawling jobs: codebase-wide migrations, audits, multi-hour unattended-style work
- Clearer communication than Opus 5, which matters when you are reviewing agent output for hours
- Adaptive thinking is always on; forced tool use is retired
- Available in Claude Code and on AI Gateway asanthropic/claude-opus-5.5### Costs (be transparent)
Per 1M tokens vs Opus 5:
| Opus 5.5 | Opus 5 | |
|---|---|---|
| Input | $4 | $5 |
| Output | $20 | $25 |
| Cache reads | $0.20 | $0.50 |
Fast mode is available at $8 / $40 when you need more speed. Opus 5.5 is cheaper than Opus 5, and that is real. It is still usually more expensive per token than Grok 4.7 or Sol/Luna on their published list rates. If your budget is tight and the task is "good enough in Cursor or Codex," pay less elsewhere. If the job is a painful migration and Claude Code is where you finish work, Opus 5.5 is often worth the premium.
Caveats
- Safeguards are similar in spirit to Fable 5.1 for cyber and biology workloads; some specialised tasks may be routed or gated
- Preserved thinking applies for newer API accounts (see Anthropic docs if you build tooling on the raw API)
- Check Anthropic's announcement and the Gateway changelog when rates or limits move
Grok 4.7 (Cursor)
Released 21 Sep 2026. Cursor describes Grok 4.7 as its most capable model for long-running coding and knowledge work: larger base than 4.6, trained on harder multi-hour tasks, stronger self-verification.
Strengths
- Built for difficult, multi-step Cursor agent sessions that used to stall on 4.6
- Effort levels: low, medium, high (default), xhigh so you can spend more compute on harder tasks
- 256k standard context, 500k long context
- Lives in the same Cursor Models pool as 4.6 and Composer on paid plans
Costs
Same on-demand list rates as Grok 4.6 in Cursor:
- Standard: $2 input / $0.50 cached / $6 output per 1M
- Fast: $4 / $1 / $12
- Above 256k input, rates increase (standard requests bill higher; see Cursor's Grok 4.7 docs)
On included plan usage, Grok 4.7 draws from the Cursor Models pool. Composer remains the everyday/fast pick; Grok 4.7 is for the harder, longer sessions. That split is the practical way to keep Cursor bills sane.
Caveats
- On Cursor Start (where available), effort may be fixed and Fast limited; Pro+unlocks the full dials
- Long-context billing is easy to forget: once you push past 256k input, expect higher rates
- Confirm details on Cursor's Grok 4.7 post and help page
GPT-6 Sol and Luna (Codex / AI Gateway)
Available on Vercel AI Gateway from 22 Sep 2026. OpenAI's GPT-6 Sol and Luna bring GPT-6 improvements in professional work, coding, computer use, factuality, and communication at a lower price than GPT-6 Astra.
Roles
- Sol (openai/gpt-6-sol`): complex professional workflows and sustained coding where quality and room to iterate both matter
- Luna (
openai/gpt-6-luna): lower-cost option for high-volume agentic workflows, coding, and everyday tasks
Both communicate more directly than their GPT-5.6 counterparts, with better factual reliability and fewer misleading "done" claims during coding tasks. Use them from Codex (including via npx vercel ai-gateway setup) or any AI Gateway client.
Costs (official list rates)
From OpenAI / AI Gateway model pages (standard short-context):
| Model | Input / 1M | Cached input / 1M | Output / 1M |
|---|---|---|---|
| Sol | $2.00 | $0.20 | $10.00 |
| Luna | $0.10 | $0.01 | $0.50 |
Prompts with very large input (OpenAI documents a threshold around 272k tokens) can bill at higher multipliers for the full request. Fast / Batch / Flex variants also change the effective rate. Treat Astra as the older/high tier: pay up when Sol is not enough and you explicitly need that tier.
Sol undercuts Astra. Luna is the volume winner. Neither is "free," but Luna especially is where you run lots of agent loops without treating every call like a premium Opus session.
Caveats
- Quality vs cost is the trade: Sol for serious sustained coding; Luna when throughput wins
- Wire Codex through AI Gateway when you want one key, usage tracking, and the Gateway catalog
- Confirm playground pricing on Vercel's Sol & Luna changelog and the OpenAI model pages linked above
Pick this if...
Pick Claude Opus 5.5 if...
- You're in Claude Code and the job is a migration, audit, or multi-hour agent run
- You want the model that stays readable as a collaborator across a long session
- You accept a higher list $/M than Grok or Luna because finishing the hard job matters more
Pick Grok 4.7 if...
- You live in Cursor and the task is harder or longer than Composer should carry
- You want effort levels (including xhigh) and large context with first-party Cursor billing
- You want frontier capability at Cursor's $2 / $6 on-demand shape (cheaper than Opus list rates)
Pick GPT-6 Sol if...
- You're in Codex (or Gateway) and need sustained coding quality with room to iterate
- You want GPT-6-class work without jumping straight to Astra pricing
- Direct, less jargony communication and stronger factual behaviour matter for your reviews
Pick GPT-6 Luna if...
- You're running high-volume agentic or everyday coding on OpenAI / Gateway
- Token burn is the constraint and Sol would be overkill
- You still want GPT-6 improvements over older cheap models
Keep Composer (Cursor) if...
- The change is small, local, and you care about speed/cost more than max capability
- You're saving Grok 4.7 for the sessions that actually need it
Practical recommendation for the Buildcamp stack
You're building Next.js web apps, Expo mobile apps, and Supabase backends. The agent choice is usually about where you already have flow, not which logo won a benchmark this week.
- Default hard job in Claude Code: Opus 5.5. Use it for schema migrations, RLS-heavy refactors, multi-file feature work that needs a patient collaborator.
- Default hard job in Cursor: Grok 4.7. Keep Composer for everyday edits. Turn effort up when the agent is circling.
- Default hard job in Codex: Sol. Drop to Luna for repetitive agent loops, codegen volume, or when you're exploring cheaply.
- Budget reality: Grok 4.7 and Luna usually win on price. Opus 5.5 usually wins when Claude Code is how you ship the scary change. Sol sits in the middle for Codex users who want quality without Astra.
A simple student workflow that stays honest:
- Morning product UI polish in Cursor → Composer, escalate to Grok 4.7 when stuck
- Afternoon Supabase + Next.js migration in Claude Code → Opus 5.5
- Overnight or high-volume Codex experiments → Luna, promote important threads to Sol
You do not need one model forever. You need a clear default per agent, and the discipline to pay for the premium brain only when the task earns it.
Official announcements
- Introducing Claude Opus 5.5 (Anthropic)
- Claude Opus 5.5 on Vercel AI Gateway
- Introducing Grok 4.7 (Cursor)
- Grok 4.7 help / usage (Cursor)
- GPT-6 Sol and Luna on AI Gateway (Vercel)
- GPT-6 Sol model (AI Gateway)
- GPT-6 Luna model (AI Gateway)
Final recommendation
| Goal | Recommendation |
|---|---|
| Long Claude Code migrations / audits | Claude Opus 5.5 |
| Hard long Cursor sessions | Grok 4.7 |
| Everyday Cursor speed | Composer |
| Sustained Codex quality | GPT-6 Sol |
| High-volume Codex / Gateway | GPT-6 Luna |
| Lowest list $/M among the three frontiers | Grok 4.7 (or Luna on OpenAI) |
| Buildcamp Next.js / Expo / Supabase shipping | Match the agent you use for that slice of work; escalate model only when stuck |
Claude Opus 5.5 vs Grok 4.7 vs GPT-6 Sol isn't about crowning one forever winner. It's about matching a frontier model to Claude Code, Cursor, or Codex for the job in front of you, with eyes open on price.
For most Buildcamp students shipping real apps this week: learn all three agents, keep a cheap default in each, and spend on Opus, Grok 4.7, or Sol when the session is actually hard.