[JackyHsu-X]

AMQP decimal fields are decoded with division, so the active decimal context can round valid message headers or raise an arithmetic exception. For example, decoding coefficient 2147483647 with scale 2 at precision 3 returns Decimal('2.15E+7') instead of Decimal('21474836.47'); enabling the Inexact trap makes decoding fail.

Construct the Decimal directly from its sign, digits and negative wire scale. This avoids context-dependent arithmetic and keeps the wire value exact without changing the caller's flags or settings.

The regression test decodes a raw field table containing both a nested table and an array, followed by an integer field. It covers signed 32-bit boundaries, scales 0 and 255, zero, low precision, restricted exponent bounds and enabled/disabled Inexact traps, and checks the final byte offset and unchanged context flags. A changelog entry is included.

Validation on Windows / Python 3.13.15:

• Before the fix: 8 regression failures, 2 passes.
• After the fix: python -m pytest t/unit t/integration -q — 400 passed, 27 skipped (RabbitMQ-dependent tests).
• Repository pre-commit hook and git diff --check passed.
• Flake8 on the changed Python files reports two existing findings (E123 and E275), both also present in the base versions; no new findings.

No live RabbitMQ or full Python-version matrix was run. This addresses decoding only; #487 addresses positive exponents on the encoding side.

Developed with assistance from OpenAI Codex.

Upstream integration (2026-11-02)

Updated the branch for main 9d4a51a (5.4.2). The only conflict was in Changelog: the pending Decimal fix remains in Unreleased, above the complete upstream 5.4.2 release notes. Upstream version changes are retained; the decoder and regression-test blobs are unchanged. Relative to updated main, the contribution remains three files, 39 insertions / 2 deletions.

The merged checkout passes all unit and simulated-protocol integration tests: 400 passed, 27 broker-dependent skips. Latest upstream still fails 8 of the 10 Decimal-context regression cases; the two zero-value controls pass. The configured trailing-whitespace hook was run directly from its existing v6.0.0 cached environment and passed, along with git diff --check. No dependency was installed or upgraded. Real RabbitMQ, other operating systems and the full Python matrix were not run. Codex prepared and validated this integration.

[auvipy]

@LuisFigueroaG can you review this?

[JackyHsu-X]

Updated the branch for main 9d4a51a (5.4.2). The only conflict was in Changelog: the pending Decimal fix remains in Unreleased, above the complete upstream 5.4.2 release notes. Upstream version changes are retained; the decoder and regression-test blobs are unchanged. Relative to updated main, the contribution remains three files, 39 insertions / 2 deletions.

The merged checkout passes all unit and simulated-protocol integration tests: 400 passed, 27 broker-dependent skips. Latest upstream still fails 8 of the 10 Decimal-context regression cases; the two zero-value controls pass. The configured trailing-whitespace hook was run directly from its existing v6.0.0 cached environment and passed, along with git diff --check. No dependency was installed or upgraded. Real RabbitMQ, other operating systems and the full Python matrix were not run. Codex prepared and validated this integration.