from __future__ import annotations import dataclassesimport hashlibimport pathlib  MIB = 1_048_576  class PgsoError(RuntimeError):    pass  @dataclasses.dataclass(frozen=True)class BuildIdentity:    source_sha: str    target: str    host_arch: str    zig_version: str    llvm_version: str    bitcode_sha256: str    corpus_sha256: str    update_channel: str    generation_flags: tuple[str, ...]  @dataclasses.dataclass(frozen=True)class ArtifactEvidence:    size_bytes: int    size_mib: float    ceiling_mib: float    headroom_mib: float    preferred_headroom_mib: float    preferred_headroom_met: bool  def sha256_file(path: pathlib.Path) -> str:    digest = hashlib.sha256()    with path.open("rb") as stream:        for chunk in iter(lambda: stream.read(1024 * 1024), b""):            digest.update(chunk)    return digest.hexdigest()  def profile_evidence(    path: pathlib.Path,    *,    merged_raw_profiles: int,) -> dict[str, object]:    if not path.is_file() or path.stat().st_size == 0:        raise PgsoError(f"profile is missing or empty: {path}")    if merged_raw_profiles <= 0:        raise PgsoError("merged raw profile count must be positive")    return {        "sha256": sha256_file(path),        "size_bytes": path.stat().st_size,        "merged_raw_profiles": merged_raw_profiles,    }  def verify_identity(expected: BuildIdentity, actual: BuildIdentity) -> None:    for field in dataclasses.fields(BuildIdentity):        expected_value = getattr(expected, field.name)        actual_value = getattr(actual, field.name)        if expected_value != actual_value:            raise PgsoError(                f"identity mismatch: {field.name}: "                f"expected {expected_value!r}, got {actual_value!r}"            )  def bytes_to_mib(byte_count: int) -> float:    return byte_count / MIB  def size_gate(    byte_count: int,    ceiling_mib: float = 7.800,    preferred_headroom_mib: float = 0.250,) -> ArtifactEvidence:    if byte_count <= 0:        raise PgsoError("artifact is empty or has an invalid negative size")     size_mib = bytes_to_mib(byte_count)    if size_mib > ceiling_mib:        raise PgsoError(            f"artifact size {size_mib:.6f} MiB exceeds "            f"{ceiling_mib:.3f} MiB ceiling"        )     headroom_mib = ceiling_mib - size_mib    return ArtifactEvidence(        size_bytes=byte_count,        size_mib=size_mib,        ceiling_mib=ceiling_mib,        headroom_mib=headroom_mib,        preferred_headroom_mib=preferred_headroom_mib,        preferred_headroom_met=headroom_mib >= preferred_headroom_mib,    )  def require_empty_stderr(stage: str, stderr: str) -> None:    if stderr:        raise PgsoError(f"{stage} wrote unexpected stderr: {stderr}")