# CorpusFetch Method Slice (Zero-Prose Python Stdlib Reference)
# Canonical Residual: https://corpusfetch.com/c/why-does-losing-intermediate-falsification-steps-weaken-the-final-stored-conclusion.md
# Remnant Warrant:    https://corpusfetch.com/c/why-does-losing-intermediate-falsification-steps-weaken-the-final-stored-conclusion.warrant.json
# Markdown SHA-256:   62c980d37257e950f3e76bf46008ee4293635b9eb90fead5b89260d5a3f1d7bc
# Code AST SHA-256:   1281c19796fd43c3523af37f45c9068a2f0b791a1172631fff2e58c4d9cc7f2a
# Verified Classes:   FalsifiedHypothesisStep, ConcludedResidualCandidate, FalsificationLineageTruncationViolation, FalsificationPreservationGate
# Defensive Guards:   3 fail-closed invariants (zero external deps)

from dataclasses import dataclass
from typing import Final, FrozenSet, Tuple
import hashlib

@dataclass(frozen=True)
class FalsifiedHypothesisStep:
    hypothesis_id: str
    candidate_strategy: str
    refuting_counterexample: str
    observed_failure_class: str

@dataclass(frozen=True)
class ConcludedResidualCandidate:
    slug: str
    final_conclusion_summary: str
    required_defensive_guards: FrozenSet[str]
    preserved_falsifications: Tuple[FalsifiedHypothesisStep, ...]
    discarded_falsification_count: int

class FalsificationLineageTruncationViolation(Exception):
    """Raised when a stored conclusion strips intermediate falsification steps or leaves defensive guards unjustified."""
    pass

class FalsificationPreservationGate:
    def verify_epistemic_lineage(self, candidate: ConcludedResidualCandidate) -> str:
        # 1. Fail-closed if any intermediate falsification steps were discarded during summarization
        if candidate.discarded_falsification_count > 0:
            raise FalsificationLineageTruncationViolation(
                f"Residual '{candidate.slug}' discarded {candidate.discarded_falsification_count} "
                "intermediate falsification step(s); refusing lossy conclusion commit."
            )

        # 2. Require at least one preserved falsification step when defensive guards are mandated
        if candidate.required_defensive_guards and not candidate.preserved_falsifications:
            raise FalsificationLineageTruncationViolation(
                f"Residual '{candidate.slug}' mandates defensive guards without preserving "
                "the falsification steps that proved them necessary."
            )

        # 3. Verify every falsified step contains a concrete counterexample and failure class
        lineage_tokens = [candidate.slug, candidate.final_conclusion_summary]
        for step in candidate.preserved_falsifications:
            if not step.refuting_counterexample.strip() or not step.observed_failure_class.strip():
                raise FalsificationLineageTruncationViolation(
                    f"Falsified hypothesis '{step.hypothesis_id}' lacks a concrete counterexample or failure class."
                )
            lineage_tokens.append(f"{step.hypothesis_id}:{step.observed_failure_class}:{step.refuting_counterexample}")

        return hashlib.sha256("|".join(lineage_tokens).encode("utf-8")).hexdigest()