[koladefaj]

Summary

• Added PyYAML~=6.0.3 to the core dependencies. import molto imports yaml through molto.core, molto.adapters.anthropic, and molto.utils.io, so a plain pip install molto failed with ModuleNotFoundError: No module named 'yaml'.
• CI did not catch the missing dependency because it installs .[test], and the test extra's fastapi[standard] requires uvicorn[standard], which requires pyyaml>=5.1.
• Added a CI step that installs Molto with core dependencies only and imports it before the test extras are installed, so an undeclared runtime dependency now fails CI instead of being masked by a transitive test dependency.
• read_yaml, read_json, and dump_yaml now open files as UTF-8. They previously used the platform default encoding, so on Windows (cp1252) 17 replay tests failed with UnicodeDecodeError on curly quotes in UTF-8 cassettes, and the matcher scripts would have written cassettes as cp1252. dump_yaml already accepted encoding="utf-8", but PyYAML ignores that argument for text streams, so it now applies to the opened file.
• Added regression tests in tests/utils/test_io.py for UTF-8 reads and writes. They fail without the fix on Windows; on Linux, where the default is already UTF-8, they pass either way.

Verification

• Core-only uv pip install -e . then python -c "import molto" on main (81f0165) in a fresh Python 3.12 venv: failed with ModuleNotFoundError: No module named 'yaml' (exit code 1), confirming the new CI step catches the defect. With this change on c7ea914: passed (exit code 0).
• python -m pytest tests/utils/test_io.py on Windows without the io.py fix: 3 failed (the new tests). With the fix: 7 passed.
• python -m pytest on Windows, UTF-8 mode off: 2297 passed (17 failed before the io.py fix). With PYTHONUTF8=1: 2297 passed. Cassettes unchanged.
• uv run --extra lint ruff check --config pyproject.toml . and ruff format --diff: changed files pass; the only findings are in the untracked local test_molto.py, which is not part of this change.
• npx prettier@3.8 --check .: passed.
• CI itself was not run; the workflow change is verified only by running its commands locally.

🤖 Generated with Claude Code

[github-actions]

Coverage Report (Python 3.14) •

File	Stmts	Miss	Cover	Missing
utils
io.py	68	13	81%	55–56, 60–61, 88–90, 164–167, 172–173
TOTAL	3913	529	86%

Tests	Skipped	Failures	Errors	Time
2299	0 💤	0 ❌	0 🔥	28.216s ⏱️

[github-actions]

Coverage Report (Python 3.13) •

File	Stmts	Miss	Cover	Missing
utils
io.py	68	13	81%	55–56, 60–61, 88–90, 164–167, 172–173
TOTAL	3958	529	87%

Tests	Skipped	Failures	Errors	Time
2299	0 💤	0 ❌	0 🔥	57.547s ⏱️

[github-actions]

Coverage Report (Python 3.12) •

File	Stmts	Miss	Cover	Missing
utils
io.py	68	13	81%	55–56, 60–61, 88–90, 164–167, 172–173
TOTAL	3958	529	87%

Tests	Skipped	Failures	Errors	Time
2299	0 💤	0 ❌	0 🔥	58.724s ⏱️

[jiahuei]

The core-only import check is useful. The PyYAML dependency can be scoped to the test extra by deferring the YAML-helper imports, as detailed inline; the UTF-8 fixes should be retained.