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GPT 5.6 Luna max vs GPT 6.1 Sol medium

GPT 6.1 Sol medium leads on speed and cost; quality is too close to call.

Quality
+7.8 pts
GPT 5.6 Luna max
11–6 head to head, 3 tied
Speed
2.4× faster
GPT 6.1 Sol medium
11.8 min vs 28.5 min per task
Cost
4.1× cheaper
GPT 6.1 Sol medium
$1.10 vs $4.49 per task

24 tasksData from

Stet score

GPT 5.6 Luna maxcodex · max reasoningRank 2 of 16

70.395% range 57.6–82.27.8 points higher

GPT 6.1 Sol mediumcodex · medium reasoningRank 4 of 16

62.595% range 53.0–71.7

A directional read: their 95% score ranges overlap.

Quality

Head-to-head matchups

GPT 5.6 Luna max won11

Tied34 undecided

GPT 6.1 Sol medium won6

GPT 5.6 Luna max’s win share 62%, 95% range 42–81%Ties are within judge noise.

Task by task

GPT 5.6 Luna max solved 0 tasks that GPT 6.1 Sol medium didn’t, and GPT 6.1 Sol medium solved 2 that GPT 5.6 Luna max didn’t. Both solved 10; neither solved 8.

On the 10 tasks both solved, judges preferred GPT 5.6 Luna max’s patch on 6, GPT 6.1 Sol medium’s on 1, and called 3 even.

stet-15439c21Solved by 13 of 16 setups

  • GPT 5.6 Luna maxFailed
  • GPT 6.1 Sol mediumPassed tests

Judges preferred GPT 6.1 Sol medium’s patch

A task counts as solved when its tests passed or a judge found the fix equivalent to the merged change, as in the leaderboard’s Solved column. Stet score also weighs code quality, so it can order the two differently. 4 of the 24 tasks are left out because one of the two has no scored result on them.

All 20 compared tasks
Task by task
TaskGPT 5.6 Luna maxGPT 6.1 Sol mediumSolved byBetter patch
stet-3169aefaPassed testsPassed testsBothEven
stet-89dfbc27Passed testsPassed testsBothEven
stet-b28f4fe7Passed testsPassed testsBothGPT 5.6 Luna max
stet-232b50baPassed testsPassed testsBothGPT 5.6 Luna max
stet-5276aa3fPassed testsPassed testsBothGPT 5.6 Luna max
stet-commit-bbbbae09Passed testsPassed testsBothGPT 5.6 Luna max
stet-66762b4cEquivalent to the merged fixPassed testsBothGPT 6.1 Sol medium
stet-15439c21FailedPassed testsGPT 6.1 Sol medium onlyGPT 6.1 Sol medium
stet-commit-5d766ddeEquivalent to the merged fixEquivalent to the merged fixBothGPT 5.6 Luna max
stet-43493c52Passed testsPassed testsBothEven
stet-6f84e978FailedEquivalent to the merged fixGPT 6.1 Sol medium onlyGPT 6.1 Sol medium
stet-2450ca2dFailedFailedNeitherGPT 5.6 Luna max
stet-commit-342d0ac0Equivalent to the merged fixEquivalent to the merged fixBothGPT 5.6 Luna max
stet-commit-60a0e6c2FailedFailedNeitherGPT 6.1 Sol medium
stet-commit-5e075641FailedFailedNeitherGPT 5.6 Luna max
stet-commit-a8716b88FailedFailedNeitherGPT 5.6 Luna max
stet-commit-e928166fFailedFailedNeitherGPT 6.1 Sol medium
stet-commit-30506f8eFailedFailedNeitherGPT 5.6 Luna max
stet-commit-d2ab0c25FailedFailedNeitherGPT 5.6 Luna max
stet-commit-e41c2e2dFailedFailedNeitherGPT 6.1 Sol medium

Side by side

Side by side
MetricGPT 5.6 Luna maxGPT 6.1 Sol medium
Harnesscodexcodex
Reasoning effortmaxmedium
Rank2 of 164 of 16
Stet score70.395% range 57.6–82.262.595% range 53.0–71.7
Solved10/247 passed, 3 judged equivalent13/2410 passed, 3 judged equivalent
Cost / task$4.49$1.10
Agent time / task28.5 min11.8 min

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