human-voice-rewrite-demo/main.py

"""Human Voice Rewrite Demo backend (PRD v1.1).

Serves the static demo page and domain endpoints that run the real
OpenRouter pipeline. Run via ./local_start.sh.
"""

from __future__ import annotations

from pathlib import Path
from typing import Any, Callable

from fastapi import FastAPI, HTTPException
from fastapi.responses import FileResponse

from evidence import sanitize_diagnosis
from llm import LLMError, LlmClient
from prompts import (
    build_analyze_prompt,
    build_diagnose_prompt,
    build_recheck_prompt,
    build_reference_prompt,
    build_scaffold_prompt,
    build_translate_prompt,
    normalize_diagnose_payload,
)
from schemas import (
    AnalyzeRequest,
    AnalyzeResponse,
    DiagnoseRequest,
    DiagnoseResponse,
    GlobalChecks,
    RecheckRequest,
    RecheckResponse,
    ReferenceRequest,
    ReferenceResponse,
    RevisionTarget,
    ScaffoldRequest,
    ScaffoldResponse,
    TranslateRequest,
    TranslateResponse,
)

app = FastAPI(title="Human Voice Rewrite Demo", version="1.1.0")

client: LlmClient | None = None
HERE = Path(__file__).resolve().parent


def get_client() -> LlmClient:
    global client
    if client is None:
        client = LlmClient()
    return client


def run_json(phase: str, system: str, user: str, check: Callable[[dict[str, Any]], str | None] | None = None) -> dict:
    try:
        return get_client().complete_json(system, user, validate=check)
    except LLMError as exc:
        raise HTTPException(status_code=502, detail=f"{phase}失败：{exc}") from exc


def _count_check(expected: int, key: str) -> Callable[[dict[str, Any]], str | None]:
    """返回语义校验器：LLM 输出里按段组织的数组条目数必须与输入段数一致。

    不一致时返回一行中文说明（触发 complete_json 重试一次；两次都失败才变
    502 单行错误）——真因：真实 LLM 偶发返回合法 JSON 但段落条目不全，
    此前无数量校验被静默接受，AI 初审出现"4 段标题只显示 1 段"（用户实测）。"""

    def check(data: dict[str, Any]) -> str | None:
        got = len(data.get(key) or [])
        if got != expected:
            return f"结果段落数与输入不一致（输入 {expected} 段，返回 {got} 段）"
        return None

    return check


def _friendly_validation(exc: Exception) -> str:
    """把 pydantic ValidationError 压缩成一行用户可读摘要（PRD §11 失败兜底：
    返回用户可读错误，不把完整校验堆栈甩给页面）。"""
    errs = getattr(exc, "errors", lambda: [])()
    if not errs:
        return f"结果格式不符合预期：{exc}"
    parts = []
    for e in errs[:2]:
        loc = " → ".join(str(x) for x in e.get("loc", []))
        parts.append(f"{loc}：{e.get('msg', '')}" if loc else e.get("msg", ""))
    more = f"（共 {len(errs)} 处）" if len(errs) > 2 else ""
    return "结果格式不符合预期：" + "；".join(parts) + more


@app.get("/api/health")
def health() -> dict:
    return {"status": "ok"}


@app.post("/api/analyze", response_model=AnalyzeResponse)
def analyze(req: AnalyzeRequest) -> AnalyzeResponse:
    if not any(p.strip() for p in req.paragraphs):
        raise HTTPException(status_code=422, detail="文本为空，无法开始分析")
    system, user = build_analyze_prompt(req.prompt, req.word_limit, req.paragraphs, req.constraints)
    data = run_json("分析", system, user, check=_count_check(len(req.paragraphs), "paragraphs"))
    try:
        return AnalyzeResponse.model_validate(data)
    except Exception as exc:  # pydantic ValidationError etc.
        raise HTTPException(status_code=502, detail=f"分析{_friendly_validation(exc)}") from exc


@app.post("/api/diagnose", response_model=DiagnoseResponse)
def diagnose(req: DiagnoseRequest) -> DiagnoseResponse:
    system, user = build_diagnose_prompt(
        req.prompt,
        req.word_limit,
        req.paragraphs,
        req.confirmed_anchors,
        req.global_constraints,
        req.paragraph_constraints,
        req.initial_analysis,
    )
    data = run_json("诊断", system, user, check=_count_check(len(req.paragraphs), "paragraph_briefs"))
    data = normalize_diagnose_payload(data)
    try:
        resp = DiagnoseResponse.model_validate(data)
    except Exception as exc:
        raise HTTPException(status_code=502, detail=f"诊断{_friendly_validation(exc)}") from exc
    return sanitize_diagnosis(resp, req.paragraphs)


@app.post("/api/recheck", response_model=RecheckResponse)
def recheck(req: RecheckRequest) -> RecheckResponse:
    if len(req.original_paragraphs) != len(req.rewrite_paragraphs):
        raise HTTPException(status_code=422, detail="原文段数与改写段数不一致")
    if any(not p.strip() for p in req.rewrite_paragraphs):
        raise HTTPException(status_code=422, detail="存在空段：全部段落完成改写后才能提交复检")
    system, user = build_recheck_prompt(req)
    data = run_json("复检", system, user)
    if isinstance(data.get("status"), str):
        data["status"] = "pass" if data["status"] == "pass" else "revision_required"
    if not data.get("checked_rewrite_version"):
        data["checked_rewrite_version"] = req.rewrite_version or ""
    try:
        resp = RecheckResponse.model_validate(data)
    except Exception as exc:
        raise HTTPException(status_code=502, detail=f"复检{_friendly_validation(exc)}") from exc
    if resp.status == "revision_required" and not resp.revision_targets:
        resp = RecheckResponse(
            status="revision_required",
            checked_rewrite_version=resp.checked_rewrite_version or req.rewrite_version,
            global_checks=resp.global_checks or GlobalChecks(),
            revision_targets=[
                RevisionTarget(
                    paragraph_id="p1",
                    blocking_issue="模型判定需要返工但未指明段落",
                    single_revision_goal="重读当前段改写并修正最明显的问题",
                )
            ],
        )
    return resp


@app.post("/api/scaffold", response_model=ScaffoldResponse)
def scaffold(req: ScaffoldRequest) -> ScaffoldResponse:
    system, user = build_scaffold_prompt(
        req.paragraph_id,
        req.original_text,
        req.semantic_anchor,
        req.rewrite_goal,
        req.global_constraints,
        req.paragraph_constraints,
    )
    data = run_json("写作起点", system, user)
    try:
        resp = ScaffoldResponse.model_validate(data)
    except Exception as exc:
        raise HTTPException(status_code=502, detail=f"写作起点{_friendly_validation(exc)}") from exc
    resp.paragraph_id = resp.paragraph_id or req.paragraph_id
    return resp


@app.post("/api/reference", response_model=ReferenceResponse)
def reference(req: ReferenceRequest) -> ReferenceResponse:
    goal = req.rewrite_goal or req.primary_goal
    system, user = build_reference_prompt(
        req.paragraph_id,
        req.original_text,
        req.semantic_anchor,
        goal,
        req.global_constraints,
        req.paragraph_constraints,
    )
    data = run_json("参考片段", system, user)
    try:
        resp = ReferenceResponse.model_validate(data)
    except Exception as exc:
        raise HTTPException(status_code=502, detail=f"参考片段{_friendly_validation(exc)}") from exc
    snippet = resp.reference_snippet or resp.starter
    resp.paragraph_id = resp.paragraph_id or req.paragraph_id
    resp.starter = snippet
    resp.reference_snippet = snippet
    return resp


@app.post("/api/translate", response_model=TranslateResponse)
def translate(req: TranslateRequest) -> TranslateResponse:
    """体验优化：改写区「译成中文对照」——顾问自查改写后原意/细节是否保留。"""
    if not req.text.strip():
        raise HTTPException(status_code=422, detail="没有可翻译的文本")
    system, user = build_translate_prompt(req.text)
    data = run_json("翻译", system, user)
    translation = data.get("translation")
    if isinstance(translation, list):  # 模型偶发把字符串字段返回成数组
        translation = "".join(str(x) for x in translation)
    resp = TranslateResponse(paragraph_id=req.paragraph_id, translation=str(translation or "").strip())
    if not resp.translation:
        raise HTTPException(status_code=502, detail="翻译结果为空，请重试")
    return resp


@app.get("/")
def index() -> FileResponse:
    return FileResponse(HERE / "index.html", media_type="text/html")