How to Choose an AI Coding Model
in H2 2026: The Full Picture
Not "which is strongest" — "which fits your situation." A three-axis decision framework (budget, task complexity, context needs), a snapshot of all three camps, and a single hub for this batch's lineup content.
Both Claude and OpenAI have shipped new H2 2026 flagships available on QCode. Google's Gemini 3.5 Flash is live, but its flagship sibling Gemini 3.5 Pro remains in limited preview, with a previously rumored launch date already missed.
As of: 2026-08-08.
Decision Framework: Three Axes
Answer these three questions before comparing benchmark scores — it's more effective.
| Axis | Ask yourself | Lean toward | Typical scenario | Note |
|---|---|---|---|---|
| Budget sensitivity | Is this workload large enough that cost control matters? | Tight budget → Luna / Sonnet 5; flexible → Sol / Fable 5 | Bulk completion, CI scripts, light classification | Luna is priced at roughly 1/25 of Sol — the gap matters at high volume |
| Task complexity | Is this a long-horizon refactor or high-difficulty reasoning task, or routine feature work? | High difficulty → Sol / Fable 5; routine → Terra / Sonnet 5 | Cross-repo refactors, complex debugging, architecture decisions | On the hardest slice of tasks, the flagship success-rate gap far outweighs the price gap |
| Context needs | How much context does a single task need? | Fable 5 (1M) / Sol・Terra・Luna (1.05M) / Gemini 3.5 Flash (1.05M) | Long-document Q&A, large cross-file refactors | Current flagship context windows across all three camps are similar — not the main differentiator |
Three-Camp Snapshot
Claude (Anthropic)
Fable 5: flagship, launched 2026-06-09, $10/$50 per million tokens, SWE-Bench Pro 80.3% (official methodology). Sonnet 5: balanced mid-tier, available on QCode. Opus 4.8: previous-generation flagship, still available.
OpenAI
GPT-5.6 in three tiers: Sol (flagship, $5/$30), Terra (balanced, $2/$12), Luna (fastest, $0.20/$1.20) — fully launched 2026-07-09, price cut 7/30. GPT-5.4 and 5.4-mini retire from Codex on 2026-08-31 (ChatGPT-signed-in sessions only; API/Codex-key access is unaffected).
Gemini 3.5 Flash: live, fast multimodal tier. Gemini 3.5 Pro: still in limited Vertex AI preview; a previously rumored July launch was missed, and a new rumor points to August 12 — unconfirmed by Google, treat as a rumor, not a fact.
This Batch's Content Navigation
This page is the hub for this round of lineup content — the links below cover every new and updated article.
GPT-5.4 Retirement Migration Guide
Which tier to move to before 8/31
Fable 5 vs GPT-5.6 Sol
Flagship specs and pricing side by side
How Are Mythos 5 and Fable 5 Related?
Which one everyday users can actually access
Claude Fable 5 Pricing Guide
Official rates and real subscription cost
Fable 5's 80.3% on SWE-Bench Pro
Where the score comes from and why it's contested
Sol / Terra / Luna: How to Choose
Benchmarks, pricing, and scenarios (refreshed)
GPT-5.6 Complete Guide
Benchmarks, pricing, and access
Gemini 3.5 Pro Release Tracker
Rumors vs confirmed facts (updated with 8/12 rumor)
GPT-5.6 Pricing Guide
Three-tier pricing, caching, and cost estimates
2026 AI Model Radar
Real-time availability status for every frontier model
GPT-5.4 Retirement Migration Guide
Before the 8/31 Codex retirement: should you move to Sol, Terra, or Luna?
Claude Fable 5 vs GPT-5.6 Sol
Specs, pricing, and SWE-Bench Pro scores for both flagships, side by side.
What Is the Relationship Between Claude Mythos 5 and Fable 5?
What everyday users can actually access is Fable 5 — Mythos 5 has no public commercial access.
Recent Timeline
Key milestones across all three camps over the past two months.
GPT-5.6's three tiers fully launch
Sol, Terra, and Luna open to everyone via API and Codex; QCode adds support the same day.
GPT-5.6 price cuts
Luna cut 80% to $0.20/$1.20, Terra cut 20% to $2/$12, Sol unchanged.
New rumored Gemini 3.5 Pro launch date
The previously rumored July launch date was missed; a new rumor points to August 12, still unconfirmed by Google — treat with caution.
GPT-5.4 retires from Codex
Affects ChatGPT-signed-in sessions only; API/Codex-key users are unaffected and don't need to migrate.
About this page
This page is a decision-framework and content-navigation hub — it doesn't re-verify each model's primary facts. See the linked deep-dive pages for exact figures and sources. Pricing is sourced from the LiteLLM open pricing JSON.
FAQ
What's the first thing to check when picking an AI coding model today?
Don't jump straight to benchmark scores. Answer three questions first: budget sensitivity, task complexity, and per-task context needs. Once those are answered, the candidate list is usually down to 1-2 tiers, and benchmark scores can settle the final call.
Do all GPT-5.4 users need to migrate?
No. The 2026-08-31 retirement only affects ChatGPT-signed-in sessions. If you access it via API or a Codex key, you're unaffected and can keep using it, or migrate to the corresponding GPT-5.6 tier if you choose.
Is Gemini 3.5 Pro available yet?
Not yet. As of 2026-08-08 it remains in limited Vertex AI preview. A previously rumored July launch was missed; a new rumor points to August 12, but Google hasn't confirmed it — treat it as a rumor, not a basis for decisions.
How is this page different from the 'AI Model Radar'?
The radar page is a snapshot of which models are available/preview/restricted. This page is a decision framework for which model fits your situation, plus a hub for this batch's new and updated deep-dive content. They're complementary — read both.
Create a QCode account
Plans from ¥60 / $8.57. One key across Claude, GPT, and Gemini models.
Related Reading
2026 AI Model Radar
Real-time availability tracking for every frontier model — complements this page's decision framework.
Claude Fable 5 on SWE-Bench Pro
Where the 80.3% score comes from, and what it's actually worth as a signal.
Claude Fable 5 Pricing Guide
Official rates, cache pricing, and real subscription-vs-API cost.
Prices, benchmark scores, and launch dates on this page have been cross-checked; the Gemini 3.5 Pro launch date is an unconfirmed rumor. Information may change — always defer to each vendor's official announcements.