What happened?

On 12 August 2026, one day after Grok Bot, SpaceXAI released Grok 4.6. It is not a new foundation model. The company kept the Grok 4.5 base, ran a longer supplemental training pass, regenerated SFT trajectories with Grok 4.5 across reasoning efforts and agent harnesses, then did RL in agentic environments (knowledge work, general coding, plus domain sandboxes for kernel work, web, CAD). No new architecture or parameter count was published.

On SpaceXAI’s published table, Grok 4.6 ties GPT-5.6 Sol Max at 61 on the Artificial Analysis Intelligence Index (Grok 4.5 High: 56; Fable 5 Max: 62). Other vendor-reported rows: GDPVal-AA v2 1753, CursorBench v3.2 69.9%, Terminal-Bench v3.0 26% (v2.1 is a different, easier test — do not mix them). Pricing is unchanged at $2 / M input, $6 / M output; a fast variant is 2×. Context remains 500K. Day-one surfaces: Cursor, Grok Build, SpaceXAI API, plus OpenRouter / Vercel / Cloudflare. First-week 2× included usage in Cursor and Grok Build.

The trap in the rate card, reported by independent boards: prompts ≥ 200K tokens re-bill the entire request at $4 / $12, not just the overage. Cache is in the $0.50/M band on those same boards. New xhigh reasoning-effort sits above the 4.5 ladder.

Why this is interesting

  • Post-training is the new pretrain — Five Intelligence Index points without a new base is the August pattern (see also GLM-5.3 the same week). Capex still buys the substrate; recipe, trajectories, and environments buy the product delta. Labs that cannot keep a live RL gym will look frozen even with more wafers.
  • Price is the product — Same $2 / $6 as 4.5, tying Sol on the composite while sitting well under Fable / Opus max-effort economics. For long-horizon jobs the interesting number is $/successful run and turns-to-done, not Elo. SpaceXAI’s own pitch: fewer turns and fewer input tokens than Opus-class on long agentic work. Verify on your harness.
  • Cursor is not a launch partner, it is the house — After the June option, 4.6 shipping inside Cursor on day one is vertical integration, not co-marketing. The model that sits in the IDE developers already pay for does not need to win a new default.
  • Long-running is the eval that matters — The blog’s demos are idea → working app, self-testing on long trajectories, stronger first-pass visual/interactive work. Same category as Qwen3.8-Max and K3: session reliability, not chat Elo.
  • Vendor tables stay directional — AA Index is a third-party composite and useful. CursorBench / FrontierCode / APEX rows mix self-reported and public numbers; Terminal-Bench v3.0 at 26% vs v2.1 at ~88% is the citation trap of the month. Bake on your repo.

What it is not

Not a new 1.5T (or whatever) pretrain — secondary write-ups that recycle the 4.5 parameter rumor are guessing. Not open weights. Not proof it beats Fable 5 as a production default. Not a free pass on the 200K re-bill cliff, which will punish naive RAG dumps. Not “Grok 4.7 next week” as a planning assumption.

Bottom line

Grok 4.6 is SpaceXAI saying the frontier is now post-training plus distribution. Same base, same price, five index points, live where Cursor users already type. Against Sol’s efficiency pitch and Fable’s absolute lead, 4.6 is the cheap-enough max-effort worker for agent farms — if your jobs fit 500K, if you watch the 200K surcharge, and if the bot product sitting next to it does not spend those tokens spinning.