The Python and Dart test suites each only verified round-tripping through
their own encoder/decoder, so a Record.to_dict()/toJson() key mismatch
between the two (deleted_hlc vs deletedHlc) would have gone undetected
despite being the exact thing this shared library exists to prevent. Pin
one canonical fixture in both suites so a future divergence fails loudly
on at least one side. Also add a test for a valid-JSON-but-wrong-shape
remote push, exercising the full (ValueError, KeyError, TypeError) skip
path, not just JSON syntax errors.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_017McuA1nAi6jBT1EaS5BrVf
Extracted and generalized from diet_guard's existing tombstone-merge scheme
and GitHub Contents API client, extended with per-field HLC LWW so the same
library can also cover todo's mutable notes and wake_alarm's single-value
sync (Workstream D scoping decision, 2026-07-04). 100% branch coverage,
clean ruff/mypy/pylint/bandit.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_017McuA1nAi6jBT1EaS5BrVf
