WebAssembly: the i32 spec-tests run

Result: 19 line-cases drawn from 14 directives of the official i32.wast integer test script were checked on 2 October 2026. The Arxo package w3c.wasm_core 0.1.0, run with law 0.1.1, returned the recorded value or trap in 19 of 19 cases, with zero mismatches. The numbers belong to that package version, that engine version, and that pinned copy of the test script — file test/core/i32.wast of WebAssembly/spec at main commit 608711107b7f1edb13efd57b7d79b49477462d36 (22 September 2026), pinned by SHA-256 f3b7e8fd641893ea0989a8ab801fce0654d276d27b5cad9cf482291a422cffe8. No third-party engine was executed in this run: the comparison is against the literals written in the .wast directives themselves.

The task and the reference

WebAssembly ships an official conformance script: .wast files that assert exact values and exact traps for each instruction. The script is an external reference — it is maintained with the specification, not with either side of this comparison. The run takes a sample of its integer cases: wrap-around addition, subtraction and multiplication, signed and unsigned division and remainder including division by zero and the signed-division overflow, plus equality tests and the is-zero test. Each case carries the case facts and the question copied verbatim from the translated test suite of the package, and the expectation is the literal of the .wast directive. The public description of the language and its test suite is at the WebAssembly specification site.

What “agreement” means here

Arxo returns an evaluation document with a proof graph; the .wast directive records a value or a trap. A case agrees when the outcome projected from the Arxo answer — the value, or the fact that evaluation traps — equals the literal of the directive. The contract compares the outcome only. The trap message text is identical on both sides (integer divide by zero, integer overflow) because the package carries the same wording; that wording match is noted for information and is not part of the comparison.

Results

Case	.wast line / directive	Expectation (literal)	Arxo answer	Outcome
W01	37 add(1,1)=2	value 2	TRUE_ONLY	match
W02	41 add(0x7fffffff,1)=0x80000000	value 2147483648	TRUE_ONLY	match
W03	49 sub(0x7fffffff,-1)=0x80000000	value 2147483648	TRUE_ONLY	match
W04	59 mul(0x80000000,-1)=0x80000000	value 2147483648	TRUE_ONLY	match
W05	61 mul(0x01234567,0x76543210)=0x358e7470	value 898528368	TRUE_ONLY	match
W06a	74 div_s(5,2)=2	value 2	TRUE_ONLY	match
W06b	75 div_s(-5,2)=-2	value -2	TRUE_ONLY	match
W07	64 trap div_s(1,0)	trap	TRUE_ONLY	match
W08	66 trap div_s(0x80000000,-1)	trap	TRUE_ONLY	match
W09	85 trap div_u(1,0)	trap	TRUE_ONLY	match
W10	102 trap rem_s(1,0)	trap	TRUE_ONLY	match
W11	123 trap rem_u(1,0)	trap	TRUE_ONLY	match
W12	286 eqz(0)=1	value 1	TRUE_ONLY	match
W13a	292 eq(0,0)=1	value 1	TRUE_ONLY	match
W13b	293 eq(1,1)=1	value 1	TRUE_ONLY	match
W13c	294 eq(-1,1)=0	value 0	TRUE_ONLY	match
W14a	68 div_s(1,1)=1	value 1	TRUE_ONLY	match
W14b	69 div_s(0,1)=0	value 0	TRUE_ONLY	match
W14c	70 div_s(0,-1)=0	value 0	TRUE_ONLY	match

Grouped: wrap-around arithmetic W01–W06 (8 line-cases), traps W07–W11 (5), comparisons W12–W14 (6). Every case carries a proof graph reaching the specification sections on integer operations (4.3.2) and on expression evaluation (4.6).

Where the two systems behave differently

On this bank there are no differences to report: the recorded literal and the Arxo answer coincide on all 19 line-cases, values and traps alike.

Where the model stops

Validation directives (assert_invalid, assert_malformed) are outside this run by contract: the run executes instructions, it does not validate modules, so those directives were never asked. Instructions the package does not support — bit operations, extensions, 64-bit integers, floats, memory, calls — are untouched by the bank. And 14 directives are a sample, not the whole i32.wast script and not the whole specification: agreement on the bank is not a claim of general equivalence between implementations.

Reproducing the run

Pin the reference first: i32.wast at the commit above, confirmed by the SHA-256 shown in the Result paragraph. Pin the Arxo side: package w3c.wasm_core 0.1.0 with law 0.1.1 (program hash sha256:5dd6446a587f754c2a651643ac7560c38adf9d3160253cad4830ae17dfdd43b2 covers all 19 answers). Each case is one call of the form law ask w3c.wasm_core --case W01 --query-id main --format json, asking the truth of the expected value or trap; the recorded evaluation document holds the proof graph and the result hash for independent inspection.