"""Candidate rewrite for Builder entries (light STAR optimization)."""

from __future__ import annotations

from copy import deepcopy
from typing import Any


def _candidate_rewrite(
    agent: Any, profile: dict[str, Any], entry: dict[str, Any], section: str, *, instruction: str | None = None,
) -> dict[str, Any]:
    try:
        proposal = agent.expander.expand(
            deepcopy(entry),
            context={
                "job_type": profile.get("job_type"),
                "target_position": profile.get("target_position"),
                "entry_type": section,
                "instruction": instruction,
            },
        )
    except Exception as exc:
        proposal = {
            "generation_source": "unavailable",
            "fallback_reason": type(exc).__name__.casefold()[:48],
        }
    original = str(entry.get("description") or "").strip()
    unavailable = proposal.get("generation_source") == "unavailable"
    optimized = "" if unavailable else str(proposal.get("optimized_description") or "").strip() or original
    # The expander owns objective coverage validation. Builder must not infer
    # semantic omissions through lexical comparison or append source text after
    # an LLM rewrite.
    uncovered = [str(item).strip() for item in proposal.get("uncovered_facts") or [] if str(item).strip()]
    return {
        "optimized_description": optimized,
        "changes": proposal.get("changes") or [],
        "source": proposal.get("source") or "ai_expanded",
        "uncovered_facts": list(dict.fromkeys(uncovered))[:8],
        "optimization_unavailable": unavailable,
        **({"fallback_reason": proposal["fallback_reason"]} if proposal.get("fallback_reason") else {}),
        **({"generation_source": proposal["generation_source"]} if proposal.get("generation_source") else {}),
    }