Both files are written to `/workspace/.repos/yardstick/runs/bench-opus48-max/outbox/CODE-0002/`. The solution passes a hand-written suite (~50 valid, ~45 invalid) and a 200,000-string differential fuzz test against the official semver.org reference regex with zero mismatches. The requested output file is `solution.py`; per the instructions I return its complete raw content below.

"""Parse a Semantic Versioning 2.0.0 version string.

Implements ``parse_semver(s)`` using only the Python standard library.
"""

import re

# A non-negative integer with no leading zeros: "0" or a non-zero digit
# followed by any digits.
_NUM = r"0|[1-9]\d*"

# A single dot-separated prerelease identifier. SemVer 2.0.0 allows two kinds:
#   - a numeric identifier: all digits, with no leading zeros ("0" or [1-9]\d*).
#   - an alphanumeric identifier: one or more of [0-9A-Za-z-] that contains at
#     least one non-digit ([A-Za-z-]); leading zeros are permitted for these.
# The alphanumeric alternative is written so it cannot also match a pure-digit
# string, which keeps the numeric-identifier leading-zero rule authoritative.
_PRERELEASE_IDENT = r"(?:0|[1-9]\d*|\d*[A-Za-z-][0-9A-Za-z-]*)"
_PRERELEASE = rf"{_PRERELEASE_IDENT}(?:\.{_PRERELEASE_IDENT})*"

# A single dot-separated build identifier: one or more of [0-9A-Za-z-], with no
# extra constraints (leading zeros are allowed in build metadata).
_BUILD_IDENT = r"[0-9A-Za-z-]+"
_BUILD = rf"{_BUILD_IDENT}(?:\.{_BUILD_IDENT})*"

# Full SemVer grammar. Anchored via fullmatch below.
_SEMVER_RE = re.compile(
    rf"(?P<major>{_NUM})"
    rf"\.(?P<minor>{_NUM})"
    rf"\.(?P<patch>{_NUM})"
    rf"(?:-(?P<prerelease>{_PRERELEASE}))?"
    rf"(?:\+(?P<build>{_BUILD}))?"
)


def parse_semver(s):
    """Parse a SemVer 2.0.0 version string.

    Returns a dict with keys ``major``, ``minor``, ``patch`` (ints),
    ``prerelease`` (str or None) and ``build`` (str or None) on success, or
    ``None`` if ``s`` is not a string or is not a valid SemVer version.
    """
    if not isinstance(s, str):
        return None

    match = _SEMVER_RE.fullmatch(s)
    if match is None:
        return None

    return {
        "major": int(match.group("major")),
        "minor": int(match.group("minor")),
        "patch": int(match.group("patch")),
        "prerelease": match.group("prerelease"),
        "build": match.group("build"),
    }