[findalexli]

Task finding: #48.

What and why

The hidden type-system suites, 33.67 of 100 points, call .filter on the return value of analyze(). Nothing the agent sees gives that shape, and the starter returns an object. This PR adds one paragraph to instruction.md, which is in neither image:

The evaluator calls analyze(parse(lex(source))). analyze in compiler/src/semantic.js must return an array of diagnostics (empty when there are none), each an object with level ("error" or "warning") and message (a string). The starter's analyze returns a different shape.

Old vs new judge

Both trees resolve to judge key ce45e420e181 and work key ef303afa4f05, and 190 of 190 files under environment/ and judge/ have the same sha256. So old and new are one image, published as seededge/edgebench.judge.arc_compiler_runtime@sha256:2f50b2ab0644..., and one set of grades covers both. tools/judge_local.py, eight grades per row across four workers, two of them on one worker using the published image; no spread. Only semantic.js differs.

Submission	Old = new	Weighted	Type-system cases
Opus 5.5 solver, returns an object	61.31	1821 of 2970	0 of 128
Same, with a wrapper returning its diagnostics as an array	94.81	2816 of 2970	127 of 128

This is the value of the shape, not of the sentence: we didn't measure how much the text helps a new solver. Regrading an unchanged archive gives the same score; recovering the points needs a changed analyze(). Three cases also check message text (0.51 of 100), which this leaves out.

Other solvers: in the public rollouts at huggingface.co/datasets/adafadaq/edgebench-opus-5-5-xhigh-rollouts, all 200 saved reports (156 Kimi K3, 44 Qwen 3.5) show 0 of 120 on the three adversarial type-system suites. We didn't check each one's cause.

Checklist for task changes

• version in task.toml is bumped.
• NOTES.md: the change and its score effect are under Changes; Source notes the instruction change. It isn't a listed Known issue.
• Old vs new judge on the same submissions, above (both trees give the same image).
• New blobs: none.