Ayinde v Haringey 之后：以引用为根基的英国判例检索

Question → [LLM agent]
              ↓ tool_use(uk_legal_search)
            [API Pick UK Legal Search] → ranked authorities
              ↓ tool_use(extract_urls)
            [API Pick URL Extract] → full judgment / statute body
              ↓ Agent reads, drafts answer
              ↓ Citation-required prompt rule
          Answer with [Neutral Citation, Section/Paragraph]
              ↓ Final verification pass
          Refuse if citation can't be matched in extracted text

import re, requests
from anthropic import Anthropic

KEY = "pk_yourkey"
client = Anthropic()

def fetch_tool(path: str) -> dict:
    return requests.get(f"https://www.apipick.com{path}/tool-schema").json()["claude"]

TOOLS = [
    fetch_tool("/api/search/uk-legal"),
    fetch_tool("/api/extract"),
]

SYSTEM = """You are a UK legal research assistant. You answer questions about
England & Wales case law and UK primary legislation using the tools available.

Rules — non-negotiable:

1. Use uk_legal_search to find authorities relevant to the question.
2. For authorities you intend to cite, use extract_urls to retrieve the
   full text. Do not cite anything you have not extracted.
3. Cite every legal proposition with a neutral citation in standard form:
   [YYYY] EWHC|EWCA|UKSC NNN (Court), §[paragraph] — for cases.
   Section N(M) of the [Act Name] YYYY — for statutes, with point-in-time
   noted if relevant.
4. If the search returned no relevant authority, or the relevant text was
   not extracted, say so explicitly: "I could not retrieve a sufficient
   authority for this question. Please escalate to qualified counsel."
   Do not infer from training-data knowledge.
5. Distinguish ratio from obiter where it matters. Note when an authority
   is first instance, appellate, or Supreme Court.
6. For legislation, default to the in-force version. State the date you used.
7. This output is informational retrieval, not legal advice."""

def call_tool(b):
    paths = {"uk_legal_search": "/api/search/uk-legal", "extract_urls": "/api/extract"}
    r = requests.post(
        f"https://www.apipick.com{paths[b.name]}",
        json=b.input,
        headers={"x-api-key": KEY},
        timeout=60,
    )
    return {"type": "tool_result", "tool_use_id": b.id,
            "content": r.text, "is_error": r.status_code != 200}

NEUTRAL_CITATION = re.compile(r"\[(\d{4})\]\s+(EWHC|EWCA|UKSC)\s+\d+")

def verify_citations(answer: str, extracted_text: str) -> list[str]:
    """Return list of citations in the answer that don't appear in extracted text."""
    cites = NEUTRAL_CITATION.findall(answer)
    return [
        f"[{year}] {court}" for year, court in cites
        if f"[{year}] {court}" not in extracted_text
    ]

def legal_research(question: str) -> str:
    msgs = [{"role": "user", "content": question}]
    extracted_buffer = ""

    while True:
        r = client.messages.create(
            model="claude-sonnet-4-6",
            max_tokens=4096,
            system=SYSTEM,
            tools=TOOLS,
            messages=msgs,
        )
        msgs.append({"role": "assistant", "content": r.content})

        if r.stop_reason == "end_turn":
            answer = "\n".join(b.text for b in r.content if b.type == "text")
            unverified = verify_citations(answer, extracted_buffer)
            if unverified:
                return (
                    "REFUSED: the answer cited authorities that were not retrieved. "
                    f"Unverified: {unverified}. Escalate to qualified counsel."
                )
            return answer

        if r.stop_reason == "tool_use":
            results = []
            for b in r.content:
                if b.type != "tool_use":
                    continue
                tr = call_tool(b)
                if b.name == "extract_urls":
                    extracted_buffer += tr["content"]
                results.append(tr)
            msgs.append({"role": "user", "content": results})

print(legal_research(
    "What is the test for breach of duty by a public authority "
    "post Roberts v Soldiers, Sailors, Airmen and Families Association?"
))