feat: make crosshair-tool optional for Python 3.15+

[KRRT7]

Summary

• Makes crosshair-tool dependency conditional on python_version < '3.15' in pyproject.toml
• Adds a module-level CROSSHAIR_AVAILABLE guard in concolic_testing.py that skips concolic test generation when the package is absent

[KRRT7]

currently crosshair-tool gets built from source on 3.15+

[claude]

PR Review Summary

Prek Checks

✅ All checks passed — ruff check and ruff format both clean.

Mypy

✅ No new type errors introduced. Two pre-existing errors in concolic_testing.py (line 50 var-annotated, line 110 no-redef) exist on main as well and are unrelated to this PR.

Code Review

✅ No critical issues found. The changes are clean and well-scoped:

• crosshair-tool dependency correctly gated with python_version < '3.15' in pyproject.toml
• Runtime guard uses importlib.util.find_spec("crosshair") at module level — appropriate since crosshair is invoked via subprocess, never directly imported
• Guard placement in generate_concolic_tests() is logically ordered (after is_python() check, before is_LSP_enabled() check)
• No other files import crosshair directly, so no unguarded import errors can occur

Test Coverage

File	Main	PR	Change
codeflash/verification/concolic_testing.py	32% (56 stmts)	33% (61 stmts)	+1%
Overall	79%	79%	No change

• ✅ No coverage regression
• ℹ️ The new guard lines (module-level CROSSHAIR_AVAILABLE and the early return) add 5 new statements. Coverage slightly improved since crosshair is installed in the test environment, meaning the CROSSHAIR_AVAILABLE constant is True and the early-return branch is not taken — consistent with expected behavior.
• ℹ️ The untaken branch (if not CROSSHAIR_AVAILABLE) would only activate on Python 3.15+ where crosshair-tool is not installed. Testing this path would require mocking importlib.util.find_spec.

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Last updated: 2026-02-18