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Haiku 5.5 low vs SWE-2 Max

SWE-2 Max leads on quality: 25.1 points higher; Haiku 5.5 low leads on agent time: 6.9× faster; SWE-2 Max’s cost wasn’t recorded.

24 tasksData from

Stet score

Haiku 5.5 lowRank 10 of 14

41.395% range 34.8–47.8

SWE-2 MaxRank 1 of 14

66.495% range 56.8–75.425.1 points higher

Their 95% score ranges don’t overlap.

Cost / task

Haiku 5.5 low$0.25
SWE-2 Maxnot recorded

Agent time / task

Haiku 5.5 low9.9 min6.9× faster
SWE-2 Max68.3 min

Task by task

Haiku 5.5 low solved 1 task that SWE-2 Max didn’t, and SWE-2 Max solved 6 that Haiku 5.5 low didn’t. Both solved 10; neither solved 7.

Haiku 5.5 low only 1

  • stet-43493c52Passed tests

SWE-2 Max only 6

  • stet-6f84e978Passed tests
  • stet-2450ca2dPassed tests
  • stet-commit-342d0ac0Equivalent to the merged fix
  • stet-commit-60a0e6c2Passed tests
  • stet-commit-5e075641Passed tests
  • stet-commit-a8716b88Equivalent 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
TaskHaiku 5.5 lowSWE-2 MaxSolved by
stet-3169aefaPassed testsPassed testsBoth
stet-89dfbc27Passed testsPassed testsBoth
stet-b28f4fe7Passed testsPassed testsBoth
stet-232b50baPassed testsPassed testsBoth
stet-5276aa3fPassed testsPassed testsBoth
stet-commit-bbbbae09Passed testsPassed testsBoth
stet-15439c21Equivalent to the merged fixEquivalent to the merged fixBoth
stet-66762b4cEquivalent to the merged fixPassed testsBoth
stet-commit-f0caded9Equivalent to the merged fixPassed testsBoth
stet-commit-5d766ddeEquivalent to the merged fixPassed testsBoth
stet-43493c52Passed testsFailedHaiku 5.5 low only
stet-6f84e978FailedPassed testsSWE-2 Max only
stet-commit-f8ae1177FailedFailedNeither
stet-2450ca2dFailedPassed testsSWE-2 Max only
stet-commit-342d0ac0FailedEquivalent to the merged fixSWE-2 Max only
stet-commit-60a0e6c2FailedPassed testsSWE-2 Max only
stet-commit-5e075641FailedPassed testsSWE-2 Max only
stet-commit-2826765eFailedFailedNeither
stet-commit-a8716b88FailedEquivalent to the merged fixSWE-2 Max only
stet-commit-30506f8eFailedFailedNeither
stet-commit-87814583FailedFailedNeither
stet-commit-d2ab0c25FailedFailedNeither
stet-commit-e41c2e2dFailedFailedNeither
stet-commit-e928166fFailedFailedNeither

Side by side

Side by side
MetricHaiku 5.5 lowSWE-2 Max
Rank10 of 141 of 14
Stet score41.395% range 34.8–47.866.495% range 56.8–75.4
Solved11/247 passed, 4 judged equivalent16/2413 passed, 3 judged equivalent
Passed review8/248/24
Matched merged change9/2413/24
Cost / task$0.25not recorded
How cost was recordedreported by its harnessnot recorded
Agent time / task9.9 min68.3 min
Ran inDaytona sandboxDaytona sandbox

Where each setup is the better choice

The leaderboard’s readings on groups of tasks. Each group holds fewer tasks than the overall standings, so treat these as leads to test on your repo.

Changes up to 150 lines

11 tasks

11 tasks whose merged change was 2–149 lines in 1–2 files. The 7 small fixes below are among them.

SWE-2 Max matched the merged change more often: 8 of 11 to Haiku 5.5 low’s 7.

Changes up to 150 lines
Haiku 5.5 lowSWE-2 Max
Matched merged change7/118/11
Passed review7/117/11
Cost / task$0.02not recorded
Agent time / task2.8 min22.1 min

Small fixes

7 tasks

7 tasks whose instructions start with “Fix”. Their merged changes were 4–29 lines in 1–2 files.

Both matched the merged change on 5 of 7.

Small fixes
Haiku 5.5 lowSWE-2 Max
Matched merged change5/75/7
Passed review5/75/7
Cost / task$0.01not recorded
Agent time / task2.7 min21.5 min

Larger changes

13 tasks

13 tasks whose merged change ran over 150 lines or more than 3 files: 113–1,420 lines in 2–19 files.

SWE-2 Max matched the merged change more often: 5 of 13 to Haiku 5.5 low’s 2.

Larger changes
Haiku 5.5 lowSWE-2 Max
Matched merged change2/135/13
Passed review1/131/13
Cost / task$0.45not recorded
Agent time / task15.9 min107.3 min

From the leaderboard’s routing advice

  • Subagents: use Haiku 5.5 low.

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