Haiku 5.5 low vs Muse Spark 1.3 high

No clear quality winner: Haiku 5.5 low won 12, Muse Spark 1.3 high won 5, 7 tied; Muse Spark 1.3 high leads on cost: 2.5× cheaper; Haiku 5.5 low leads on agent time: 1.3× faster.

24 tasksData from October 29, 2026

Stet score

Haiku 5.5 lowclaude-code · low reasoningRank 13 of 16

38.995% range 32.6–45.47.0 points higher

Muse Spark 1.3 highmuse · high reasoningRank 14 of 16

31.995% range 23.5–40.6

Other setups

Muse Wonder Full low

70.4

GPT 5.6 Luna max

70.3

SWE-2 Max high

64.3

GPT 6.1 Sol medium

62.5

Opus 5 medium

62.3

Grok 4.7 high

60.7

Pareto 26.9 medium

57.1

Haiku 5.5 max

55.5

GPT 6 Sol medium

55.4

GPT 6 Luna max

47.4

DeepSeek V4.1 Flash max

45.9

Opus 4.8 medium

39.2

GLM 5.3 Flash high

29.0

GPT 6 Luna low

19.9

A directional read: their 95% score ranges overlap.

Cost / task

Haiku 5.5 low$0.25

Muse Spark 1.3 high$0.102.5× cheaper

Agent time / task

Haiku 5.5 low9.9 min1.3× faster

Muse Spark 1.3 high13.2 min

Quality

Head-to-head matchups

Haiku 5.5 low won12

Tied7

Muse Spark 1.3 high won5

Haiku 5.5 low’s win share 63%, 95% range 47–78%Ties are within judge noise.

Task by task

Haiku 5.5 low solved 2 tasks that Muse Spark 1.3 high didn’t, and Muse Spark 1.3 high solved 1 that Haiku 5.5 low didn’t. Both solved 9; neither solved 12.

Haiku 5.5 low only 2

stet-15439c21Equivalent to the merged fix
stet-commit-f0caded9Equivalent to the merged fix

Muse Spark 1.3 high only 1

stet-2450ca2dEquivalent to the merged fix

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.

All 24 compared tasks

Task by task
Task	Haiku 5.5 low	Muse Spark 1.3 high	Solved by
`stet-3169aefa`	Passed tests	Passed tests	Both
`stet-89dfbc27`	Passed tests	Passed tests	Both
`stet-b28f4fe7`	Passed tests	Passed tests	Both
`stet-232b50ba`	Passed tests	Passed tests	Both
`stet-5276aa3f`	Passed tests	Passed tests	Both
`stet-commit-bbbbae09`	Passed tests	Passed tests	Both
`stet-66762b4c`	Equivalent to the merged fix	Passed tests	Both
`stet-15439c21`	Equivalent to the merged fix	Failed	Haiku 5.5 low only
`stet-commit-5d766dde`	Equivalent to the merged fix	Equivalent to the merged fix	Both
`stet-43493c52`	Passed tests	Passed tests	Both
`stet-commit-f0caded9`	Equivalent to the merged fix	Failed	Haiku 5.5 low only
`stet-6f84e978`	Failed	Failed	Neither
`stet-2450ca2d`	Failed	Equivalent to the merged fix	Muse Spark 1.3 high only
`stet-commit-342d0ac0`	Failed	Failed	Neither
`stet-commit-f8ae1177`	Failed	Failed	Neither
`stet-commit-60a0e6c2`	Failed	Failed	Neither
`stet-commit-5e075641`	Failed	Failed	Neither
`stet-commit-2826765e`	Failed	Failed	Neither
`stet-commit-a8716b88`	Failed	Failed	Neither
`stet-commit-e928166f`	Failed	Failed	Neither
`stet-commit-30506f8e`	Failed	Failed	Neither
`stet-commit-87814583`	Failed	Failed	Neither
`stet-commit-d2ab0c25`	Failed	Failed	Neither
`stet-commit-e41c2e2d`	Failed	Failed	Neither

Side by side

Side by side
Metric	Haiku 5.5 low	Muse Spark 1.3 high
Harness	claude-code	muse
Reasoning effort	low	high
Rank	13 of 16	14 of 16
Stet score	38.995% range 32.6–45.4	31.995% range 23.5–40.6
Solved	11/247 passed, 4 judged equivalent	10/248 passed, 2 judged equivalent
Cost / task	$0.25	$0.10
Agent time / task	9.9 min	13.2 min

See which setup wins on your repo

Stet replays your merged PRs, scores quality above pass/fail, and delivers comparison reports through your agent.

Run it on your repo

About this data

24 tasks, each a merged change replayed from the repo as it was just before the merge.
Data from October 29, 2026.
Both setups come from the same leaderboard run of 16 setups: bmk_d4ba310fdf50db4ccb2092e3.

See all 16 setups on the leaderboard How Stet measures