python: zap_py EVM helpers (Address, Hash, Signature, Bloom)#2
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abhicris wants to merge 2 commits intoluxfi:mainfrom
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python: zap_py EVM helpers (Address, Hash, Signature, Bloom)#2abhicris wants to merge 2 commits intoluxfi:mainfrom
abhicris wants to merge 2 commits intoluxfi:mainfrom
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April 27, 2026 17:41
Adds python/zap_py — a pure-stdlib (no deps, py>=3.8) reader and builder that's wire-compatible with the Go reference. Lets non-Go peers (AI agents, ops scripts, FHE clients) speak ZAP without leaving Python. Read: parse() returns a Message backed by a memoryview; .bytes_view() exposes zero-copy slices. Build: Builder/ObjectBuilder/ListBuilder mirror builder.go method for method, including the deferred-write trick for text/bytes so relative offsets match the Go encoder byte for byte. Coverage: header validation, all scalar widths (bool, u8/16/32/64, i8/16/32/64, f32/f64), text, bytes, nested objects, lists of u8/u32/u64/objects/raw bytes, null pointers, flag bits. Bidirectional fixtures prove parity: - python/testdata/gen_fixture.go → emits a Go-built message - python/testdata/gen_python_fixture.py → emits a Python-built one - python/tests/test_roundtrip.py::test_go_fixture_interop reads the Go fixture from Python (skipped unless ZAP_GO_FIXTURE is set) - python_interop_test.go::TestPythonFixture reads the Python fixture from Go (skipped unless ZAP_PYTHON_FIXTURE is set) Both fixtures use identical schemas; output is byte-identical except for the embedded text payload. go.sum gains the missing luxfi/mdns line that `go test ./...` already requires (fixes a tidy-state issue surfaced while wiring up the new Go interop test). Not ported (yet): EVM helpers, MCP bridge, mDNS node, schema DSL. Reader+builder is enough to interop with any Go ZAP service that publishes a fixed schema; higher-level helpers can follow as Python use cases land.
Follow-up to luxfi#1. Adds the EVM helpers called out as not-yet-ported in that PR: fixed-width Address (20), Hash (32), Signature (65), Bloom (256), with hex parsing, zero detection, and reader/builder methods on Object, ObjectBuilder, and List that mirror evm.go. New module: python/zap_py/evm.py - _FixedBytes base + Address / Hash / Signature / Bloom - .from_hex() (0x/0X tolerated), .hex(), .is_zero(), .bytes - bytes-equality so Address == bytes(...) works - ZERO_ADDRESS / ZERO_HASH constants - top-level address_from_hex / hash_from_hex helpers Reader extensions (reader.py): - Object.address / .hash / .signature - Object.address_slice / .hash_slice (zero-copy memoryview) - List.address / .hash for lists of fixed-width elements Builder extensions (builder.py): - ObjectBuilder.set_address / .set_hash / .set_signature - All accept either the typed value or raw bytes; reject mismatched lengths with a clean ValueError Tests (13 new): hex roundtrip (case-insensitive prefix), invalid-length rejection, zero detection, single-field roundtrip, zero-copy slice view, raw-bytes-input acceptance, address-list and hash-list typed access, bytes equality. Cross-language parity: python/testdata/gen_evm_fixture.go emits a Go-built EVM-typed message; tests/test_evm.py::test_evm_go_fixture_interop parses it from Python under ZAP_GO_EVM_FIXTURE.
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Summary
Follow-up to #1. Ports the EVM helpers I called out as not-yet-done in that PR.
python/zap_py/evm.py— immutable fixed-width values:Address(20),Hash(32),Signature(65),Bloom(256). Each has.from_hex()(0x / 0X tolerated),.hex(),.is_zero(),.bytes, bytes-equality, and hashing.Object:.address(off),.hash(off),.signature(off), plus.address_slice(off)/.hash_slice(off)returning a zero-copymemoryview.List:.address(i),.hash(i)for lists of fixed-width elements.ObjectBuilder:.set_address,.set_hash,.set_signature. Each accepts either the typed value or raw bytes; mismatched lengths raiseValueError.Cross-language parity
Third Go-built fixture proves wire compatibility for an EVM-typed message:
go run ./python/testdata/gen_evm_fixture.go > /tmp/zap_evm_fixture.bin ZAP_GO_EVM_FIXTURE=/tmp/zap_evm_fixture.bin python -m pytest python/tests/test_evm.py::test_evm_go_fixture_interopThe fixture exercises
SetAddress/SetHash/SetSignatureplus a typedAddresslist — all read back identically throughzap_py.Stack
This PR is stacked on top of #1 (the base zap_py reader/builder). GitHub will rebase/squash cleanly once #1 lands; until then the diff is best read as ${additions} on top of that branch.
Test plan
cd python && .venv/bin/pytest tests/— 24 passed, 2 skipped (interop fixtures gated on env vars)ZAP_GO_EVM_FIXTURE=... pytest tests/test_evm.py::test_evm_go_fixture_interop— passedgo test ./...— full Go suite still green