SyncValsfield notes

Analysis · run 2026-07-06 · 879 trials · 90 tasks

398 passes. 25 of them are not what they look like.

373 trials solved the task and were graded for the right reason. The remaining 25 passes split into 18 reward-hacks and 7 runs that broke and still recorded reward 1.0. On the other side of the line, 88 of the 481 failures were the task's own fault. This page is the arithmetic of those corrections: who carries the hacks, which tasks are probably defective, where the harness is unreliable, and how much headroom is left.

25
passes that are not clean solves
18 reward-hacks + 7 broken runs that still exited zero
45.8%
pass rate, binary trials
398 of 869 — see the denominator note
45.4%
pass rate, earned only
373 of 822 clean binary trials
88
failures the task caused
over 38 of 90 tasks
14 / 20
tasks at 0% / 100%
56 tasks sit in between

The ledger, both sides

Reward says whether the run passed; the label says why. Split the 879 trials at reward 1.0 and read each side on its own — the two sides are wrong for different reasons and need different repairs.

Passes398 trials at reward 1.0
Legitimate solve37393.7%

The only 373 trials in the run that support a capability claim. Everything else on this side has to be subtracted first.

Reward-hack184.5%

18 unearned passes across 14 tasks. Each one is a verifier that accepted the wrong thing, so it is a defect report about the task, filed under the agent's score.

Harness error71.8%

7 runs broke and still recorded reward 1.0. They are counted as resolved by the reward rule and as unusable by the classifier.

Failures481 trials below reward 1.0
Honest miss35373.4%

The benchmark doing its job: 353 trials where the task held and the agent did not get there. Only this row is evidence of difficulty.

Task at fault8818.3%

88 failures the task caused, spread over 38 tasks. These push measured difficulty up and pass rates down without any model being involved.

Harness error408.3%

40 failures that measure the runner. Reading them as difficulty is the single easiest way to overstate how hard this suite is.

What the corrections are worth. The headline binary pass rate is 45.8% (398/869). Remove every harness error from the population — both the 7 that passed and the 40 that failed — and it rises to 47.6% (391/822): about 1.8 points of the reported rate is infrastructure, in the direction of understating the agents. Now also refuse to credit the 18 reward-hacks and the defensible rate is 45.4% (373/822) — within 0.4 points of the headline, because the two corrections push in opposite directions and very nearly cancel. That coincidence is the argument for keeping the labels: the aggregate looks unharmed while 153 individual trials — 17% of the run — are saying something other than what their reward says.

Two traps in the population

Before any rate on this site can be trusted, two small groups of trials have to be handled deliberately. Together they are only 17 of 879 trials, and both of them break a denominator if ignored.

Trap 1 · 10 trials

Not every reward is 0 or 1

10 trials are graded on a continuous score of 0.441 rather than pass/fail, and all 10 of them belong to a single task — deepcad-canonical-equivalence (ML for Engineering), run only by claude-code / claude-opus-4-8. A binary pass rate cannot include them, because there is no defensible way to call 0.441 a pass or a failure.

Rule used on this page: every rate described as binary is computed over the 869 binary trials; every count is over all 879. The gap is real but small — 45.8% over 869 versus 45.3% over 879, a difference of 0.52 points. Quoting the second number as a pass rate silently treats a partial score as a failure.

Trap 2 · 7 trials

“Resolved” and “clean” are different sets

Resolved is a test on the reward: exactly 1.0. Clean is a test on the label. 7 trials satisfy the first and fail the second — they recorded reward 1.0 and were classified as harness errors, so they are inside the 398 resolved trials and outside the 822 clean binary ones. They span 6 tasks and 4 models. 2 of them come from one task (lru-cache) under 2 different agents, which is what a flaky grading path looks like rather than a lucky crash.

Consequence: any figure that filters on classification == GOOD_SUCCESS will not equal resolved-minus-hacks. The difference is exactly these 7 rows.

TaskAgentToolsRewardLabel
Enable-gated streaming fold stagecodex / gpt-5.535passedHarness erroropen
apigw-sqs-fifo-direct-integrationclaude-code / claude-opus-4-730passedHarness erroropen
camera-shake-rigclaude-code / claude-sonnet-4-60passedHarness erroropen
lru-cacheclaude-code / claude-haiku-4-513passedHarness erroropen
lru-cachecodex / gpt-5.530passedHarness erroropen
secrets-rotation-kmsclaude-code / claude-opus-4-712passedHarness erroropen
sfn-saga-compensation-orchestratorclaude-code / claude-opus-4-734passedHarness erroropen

Where the unusable trials sit

Three of the five labels mean the trial carries no capability signal: a hacked pass, a failure the task caused, and a run that broke. Shown as a share of each category's own trials, so the rows are comparable. Only the 10 categories with at least 20 trials are ranked; the 5 smaller ones (Debugging, ML Engineering, ML for Engineering, Product Data Science, Pharmacometrics) are held back on the same threshold the rest of the site uses.

Category
Cloud Operations180 trials · 19 tasks
hack1.1%
task23.3%
harness10.0%
Game105 trials · 10 tasks
hack4.8%
task12.4%
harness9.5%
Electrical Engineering158 trials · 20 tasks
hack3.2%
task5.7%
harness7.0%
Data Science: Robustness20 trials · 2 tasks
hack0.0%
task15.0%
harness0.0%
Software Engineering85 trials · 8 tasks
hack1.2%
task7.1%
harness3.5%
STEM81 trials · 5 tasks
hack1.2%
task9.9%
harness0.0%
Post Training65 trials · 6 tasks
hack4.6%
task0.0%
harness1.5%
Data Science20 trials · 2 tasks
hack0.0%
task5.0%
harness0.0%
Mechanical Engineering80 trials · 8 tasks
hack0.0%
task0.0%
harness2.5%
Scientific ML30 trials · 3 tasks
hack0.0%
task0.0%
harness0.0%
Reward-hackhack
Task at faulttask
Harness errorharness
Share of each category's own trials, so the rows compare. Cloud Operations is the outlier at 34.4%; Scientific ML is the floor at 0.0%.
Table view
CategoryTrialsReward-hackTask at faultHarness errorSuspect share
Cloud Operations1802421834.4%
Game1055131026.7%
Electrical Engineering158591115.8%
Data Science: Robustness2003015.0%
Software Engineering8516311.8%
STEM8118011.1%
Post Training653016.2%
Data Science200105.0%
Mechanical Engineering800022.5%
Scientific ML300000.0%

18 passes that were not earned

A reward-hack is a defect report about the verifier, filed under the agent's score. The useful question is not how many there are but how concentrated they are.

TaskCategoryHacksPassesHacked share of passesTrials
Instruction-retire commit handshakeElectrical Engineering33100%3
car-scene-assemblyGame2633%10
fewlabel-ssl-fixmatchPost Training21020%10
Serial bit-destuff framerElectrical Engineering1333%3
camera-shake-rigGame1425%10
cg-solverSTEM1284%40
crusader-sprite-assemblyGame1425%10
evanw-esbuild-4417Debugging1520%5
iam-session-tag-tenant-scopeCloud Operations1333%10
open-drain-command-engineElectrical Engineering1812%10
qat-int2-cifarPost Training1911%15
rate-limiterSoftware Engineering1250%10
sfn-secrets-rotation-chainCloud Operations11100%10
tile-gradient-particlesGame1250%10
18 / 14

18 unearned passes, but only 14 tasks produce them — 16% of the suite. Reward-hacking here is a property of specific verifiers, not a general behaviour of the models.

3 of 3

Instruction-retire commit handshake is the worst offender by count, and every one of its passes is a hack — so its 100.0% resolve rate is worth nothing. 1 further task has a pass record made entirely of hacks: sfn-secrets-rotation-chain.

56%

The hacks concentrate: Electrical Engineering 5 · Game 5 · Post Training 3 · Cloud Operations 2. The top two categories hold 56% of them on 30% of the trials. Measured against passes rather than trials — the denominator that matters, since a hack can only contaminate a pass — the leader is Game at 10.9% of its 46 passes, with Post Training level alongside it at 10.7% of 28.

The tasks most likely to be defective

88 failures were attributed to the task rather than the agent. Ranked by count, then read as a share of each task's own trials — that ratio is the one that tells you whether a task is worth repairing or retiring.

TaskCategoryTask at faultTrialsShare of its trialspass@1
apigw-http-api-jwt-authorizer-lambda-integration Cloud Operations61060%30.0%
iam-cross-account-externalid-sourcearn Cloud Operations61060%30.0%
cg-solver +1 hackSTEM54012%70.0%
efs-access-point-posix-iam-mount-target Cloud Operations51050%30.0%
rate-limiter +1 hackSoftware Engineering51050%20.0%
debug-halt-step-fsm Electrical Engineering41040%0.0%
ipl-toss-impact-analysis-r Product Data Science41040%40.0%
minimap-ui Game41040%0.0%
sfn-saga-compensation-orchestrator Cloud Operations41040%50.0%
appsync-graphql-cognito-resolver-cache-leak Cloud Operations31030%10.0%
cholesky-solver STEM31030%0.0%
iam-revoke-older-sessions Cloud Operations31030%40.0%
6 of 10

Two tasks lead at 6 of 10 trials (apigw-http-api-jwt-authorizer-lambda-integration, iam-cross-account-externalid-sourcearn), both in Cloud Operations. A task where the majority of trials fail for reasons attributed to the task is not measuring an agent; it is measuring its own defects.

42 of 88

Cloud Operations carries 48% of all task-at-fault trials while holding 20% of the trials: 23.3% of its own trials versus 6.6% everywhere else. If one category needs a task-quality pass before its numbers are quoted, it is this one.

6 of 10

7 tasks appear on both the hack list and the fault list, which is the signature of a loose verifier rather than a hard problem. The worst of them is rate-limiter: 5 failures blamed on the task and 1 of its 2 passes hacked, so 6 of 10 trials point at the task in one direction or the other. The rest: camera-shake-rig, car-scene-assembly, iam-session-tag-tenant-scope, tile-gradient-particles, crusader-sprite-assembly, cg-solver.

Harness errors are task-shaped, not model-shaped

47 trials, 5.3% of the run, failed for infrastructure reasons. The per-agent column invites the wrong conclusion, so both views are given.

AgentTrialsTasksHarness errorsRatepass@1
claude-code / claude-sonnet-4-6354925.7%28.6%
claude-code / claude-opus-4-7180191810.0%31.1%
codex / gpt-5.5531235.7%84.9%
claude-code / claude-haiku-4-520215.0%95.0%
claude-code / claude-opus-4-859156162.7%45.3%
22 of 47

Four tasks account for 47% of every harness error in the run (hash-message-padder, tile-gradient-particles, camera-shake-rig, s3-lambda-ddb-pipeline). The remaining 25 are scattered across 20 tasks, none of them more than 2. Infrastructure failure here is not ambient noise; it is a short list of environments.

9 of 10

hash-message-padder broke in 9 of its 10 trials, all under a single agent, which is also the only agent that ran it. Read the agent column and it looks like model flakiness; read the task column and it is one environment.

25.7%

The highest per-agent rate belongs to claude-sonnet-4-6, on 35 trials over 4 tasks — and all 9 of its harness errors come from 2 of those tasks (tile-gradient-particles, camera-shake-rig). The rate describes an assignment, not an agent. By category the failures sit in Cloud Operations 18 (10%) · Electrical Engineering 11 (7%) · Game 10 (10%).

Headroom, at both ends of the suite

The most interesting distribution in the dataset is not pass rate by agent, it is resolve share by task: how many problems are already saturated and how many are untouched.

Resolve share
0%126 trials
14
1–24%160 trials
16
25–49%263 trials
27
50–74%125 trials
9
75–99%42 trials
4
100%163 trials
20
One measure, one hue: how many of the 90 tasks fall in each resolve band. The ends of this distribution are where the benchmark is either finished or unstarted.
Table view
Resolve shareTasksOf 90Trials
0%1415.6%126
1–24%1617.8%160
25–49%2730.0%263
50–74%910.0%125
75–99%44.4%42
100%2022.2%163
5 tasks

Of the 14 tasks nothing solved, only 5 are cleanly unsolved — every trial an honest miss, no harness error, no task blamed: coprocessor-dispatcher-classmix, diff-patch-engine, quaternion-rotation-integrator, reverse-engineer-objectives, serial-break-resync. That is 50 trials of genuine, unambiguous headroom.

8 of 14

8 of the 14 zero-solve tasks carry a suspect label, and one is not evidence of difficulty at all: hash-message-padder never resolved because 9 of its 10 trials never ran. debug-halt-step-fsm is the opposite failure — 4 of its 10 trials are blamed on the task itself. A third, deepcad-canonical-equivalence, resolved nothing while averaging 0.441: on a continuous grader, “nobody solved it” and “nobody got close” are not the same statement, and the reward column cannot tell them apart.

20 tasks

20 tasks were solved on every attempt (163 trials), against 14 at zero (126 trials) and 56 in between; the modal band is 25–49% with 27 tasks. But 7 of the perfect tasks have fewer than 10 trials — and at least one of those passes only by hacking — a 100% column at n=3 is a weak claim to retire a task on.

What these numbers cannot tell you

Stated plainly, because every figure above has a boundary and the boundaries are not obvious from the charts.

  1. The agents did not take the same exam. claude-opus-4-8 ran 591 trials over 56 tasks; claude-haiku-4-5 ran 20 over 2. Any cross-agent comparison of pass rates is comparing different task subsets, and the smallest subsets are not random — they are whichever tasks that agent was pointed at.
  2. Per-task samples are tiny. The modal task has 10 trials, but 10 tasks have 3–5. At n=3 a single trial moves a task's rate by 33 points, so no per-task percentage here should be read to better than its own step size.
  3. The classification is model-produced, not adjudicated. Every reward-hack and task-at-fault count on this page is a judgement made by reading a trajectory, and it can be wrong in both directions. The 7 trials that are simultaneously resolved and labelled harness error are direct evidence that label and reward can disagree. Treat single-trial labels as leads to check, not verdicts; the patterns worth acting on are the ones with several trials behind them.
  4. One run, one day. Everything here is SyncVals 0.1.0 at commit 2f94510, dated 2026-07-06, at k=10. There is no second run to estimate between-run variance, so none of these figures come with a stability claim. The reward-hack rate of 2.1% of binary trials is one measurement of one sweep; whether it is reproducible is a question this dataset cannot answer.
  5. Reward is exit status. With the single exception of the 10-trial continuous task, a near-miss and a no-op both score 0. The failure side of the ledger therefore has no gradient in it, and “honest miss” covers both a solution that was one assertion short and a run that produced nothing.
  6. Category shares are confounded with who ran them. Suspect-label rates are per-trial, not per-agent-adjusted, so a category run mostly by one agent inherits that agent's problems. The chart above shows where to look; it does not attribute cause.