Verified Coding Agent — Nebius Prize DOMINO 4

1

Bounded Broken-Code Task & Original Defect

INPUT

File under repaircalc.py

Functionadd_positive(a, b)

Defectreturn a - b (should be a + b)

TaskFix the subtraction defect so targeted test passes

Mission IDm-test-23-domino3-live

2

Nemotron / Token Factory — Model Proposal

MODEL PROPOSED

Model proposed ≠ verified success. This is the raw output from the language model. It has not been executed or verified yet.

ProposerNemotron / Nebius Token Factory

Model IDnvidia/NVIDIA-Nemotron-3-Nano-30B-A3B

Request IDchatcmpl-f5753ef3-258a-4eaf-a853-8c7485604152

Round1 of 1

Candidates generated1

3

Raw Model Diff (as parsed from model output)

RAW DIFF

SHA-25663d611c67d19a17ccaae0d3e8814488040152a80945b778467b2eb7465d21494

Lines added+1

Lines deleted-1

--- a/calc.py
+++ b/calc.py
@@ -4,7 +4,7 @@ def add_positive(a: int, b: int) -> int:
     # Defect: should return a + b.
-    return a - b
+    return a + b

4

Canonicalized Execution Diff (applied to sandbox)

CANON DIFF

normalization_applied = true — Only permitted unified-diff hunk-count metadata changed during normalization. The code change (- return a - b → + return a + b) is identical in both artifacts. Raw and canonicalized diffs are distinct provenance artifacts with separate SHA-256 hashes.

SHA-2562f94c44f0e3c2900ec459fe68dd5d99951040dc93364fd69b2aba97f84b3bbb9

Normalization appliedTrue

--- a/calc.py
+++ b/calc.py
@@ -4,2 +4,2 @@ def add_positive(a: int, b: int) -> int:
     # Defect: should return a + b.
-    return a - b
+    return a + b

5

ConTree / Nebius Sandboxes — Isolated Execution

SANDBOX

Execution backendConTree / Nebius Sandboxes

Candidate IDr-0-b77cd98e-c0

Resulting checkpointcontree:ccf4980b-b61f-463a-81c5-9f619d715e6c

Changed files1

The patch was applied inside an isolated ConTree sandbox (Nebius cloud execution) — not on the host machine. No model output was trusted without sandbox execution.

6

Targeted Verification

PASS

VerdictPASS

Scopetargeted

Exit code0

Test node IDscalc::add_positive(2,3)==5

Verification command

python3 -c import sys; sys.path.insert(0, '.'); from calc import add_positive; assert add_positive(2, 3) == 5

Verification SHA-25645e5efe912b786c9a7aa7d9a4dfe15956c7f24c51ec35dbc5a107b210e854aec

6b

Full-Suite Verification

NOT_REQUIRED

NOT_REQUIRED ≠ PASS and ≠ skipped due to error. Full-suite verification was architecturally not triggered for this run — it is only invoked when multiple candidates all achieve a targeted PASS and a tie-break is needed.

Full-suite statusNOT_REQUIRED

ReasonSINGLE_PASS — exactly one candidate achieved a targeted PASS; the frozen promotion cascade does not invoke full-suite tie-break verification when there is only one passing candidate.

Promotion ruleSINGLE_PASS

7

Final Decision

PROMOTED

Evidence-backed PASS. Deterministic tests passed in isolated execution. Evidence chain intact.

Promotion ruleSINGLE_PASS

Finalized at2026-09-07T23:06:42.745070Z