RAG Agent — Python (implémentation complète avec LLM)

examples/
└── agent-patterns/
    └── rag-agent/
        └── python/
            ├── main.py           # Plan -> Retrieve -> Ground -> Answer
            ├── llm.py            # retrieval planner + grounded answer composer
            ├── gateway.py        # policy boundary: intent validation + source allowlist
            ├── retriever.py      # deterministic ranking + context pack
            ├── kb.py             # local knowledge base (documents + metadata)
            └── requirements.txt

git clone https://github.com/AgentPatterns-tech/agentpatterns.git
cd agentpatterns

cd examples/agent-patterns/rag-agent/python
python3 -m venv .venv
source .venv/bin/activate
pip install -r requirements.txt

export OPENAI_API_KEY="sk-..."
# optional:
# export OPENAI_MODEL="gpt-4.1-mini"
# export OPENAI_TIMEOUT_SECONDS="60"

python main.py

from __future__ import annotations

from typing import Any

KB_DOCUMENTS: list[dict[str, Any]] = [
    {
        "id": "doc_sla_enterprise_v3",
        "source": "support_policy",
        "title": "Support Policy",
        "section": "Enterprise SLA",
        "updated_at": "2026-01-15",
        "text": (
            "Enterprise plan includes 99.95% monthly uptime SLA. "
            "For P1 incidents, first response target is 15 minutes, 24/7. "
            "For P2 incidents, first response target is 1 hour."
        ),
    },
    {
        "id": "doc_sla_standard_v2",
        "source": "support_policy",
        "title": "Support Policy",
        "section": "Standard SLA",
        "updated_at": "2025-11-10",
        "text": (
            "Standard plan includes 99.5% monthly uptime SLA. "
            "For P1 incidents, first response target is 1 hour during business hours."
        ),
    },
    {
        "id": "doc_security_incident_v2",
        "source": "security_policy",
        "title": "Security Incident Playbook",
        "section": "Escalation",
        "updated_at": "2026-01-20",
        "text": (
            "For enterprise customers, security-related P1 incidents require immediate escalation "
            "to the on-call incident commander and customer success lead."
        ),
    },
    {
        "id": "doc_refund_policy_v4",
        "source": "billing_policy",
        "title": "Billing and Refund Policy",
        "section": "Refund Eligibility",
        "updated_at": "2025-12-01",
        "text": (
            "Annual enterprise subscriptions may receive a prorated refund within 14 days "
            "under approved exception flow."
        ),
    },
    {
        "id": "doc_onboarding_checklist_v1",
        "source": "operations_notes",
        "title": "Enterprise Onboarding Checklist",
        "section": "Launch Prep",
        "updated_at": "2025-09-02",
        "text": (
            "Checklist for onboarding includes SSO setup, domain verification, and success plan kickoff."
        ),
    },
]

from __future__ import annotations

import re
from typing import Any

STOPWORDS = {
    "the",
    "and",
    "for",
    "with",
    "that",
    "this",
    "from",
    "into",
    "what",
    "which",
    "when",
    "where",
    "have",
    "has",
    "plan",
    "does",
}



def _tokenize(text: str) -> list[str]:
    tokens = re.findall(r"[a-zA-Z0-9_]+", text.lower())
    return [token for token in tokens if len(token) > 2 and token not in STOPWORDS]



def _score_document(query_tokens: list[str], doc_text: str) -> float:
    if not query_tokens:
        return 0.0

    haystack = doc_text.lower()
    overlap = sum(1 for token in query_tokens if token in haystack)
    base = overlap / len(query_tokens)

    # Boost explicit SLA intent to prefer policy-grade docs.
    phrase_boost = 0.0
    if "sla" in haystack:
        phrase_boost += 0.15
    if "p1" in haystack and "response" in haystack:
        phrase_boost += 0.1

    return round(min(base + phrase_boost, 1.0), 4)



def retrieve_candidates(
    *,
    query: str,
    documents: list[dict[str, Any]],
    top_k: int,
    allowed_sources: set[str],
) -> list[dict[str, Any]]:
    query_tokens = _tokenize(query)
    scored: list[dict[str, Any]] = []

    for doc in documents:
        if doc.get("source") not in allowed_sources:
            continue

        text = str(doc.get("text", ""))
        score = _score_document(query_tokens, text)
        if score <= 0:
            continue

        scored.append(
            {
                "doc_id": doc["id"],
                "source": doc["source"],
                "title": doc["title"],
                "section": doc["section"],
                "updated_at": doc["updated_at"],
                "score": score,
                "text": text,
            }
        )

    scored.sort(key=lambda item: item["score"], reverse=True)
    return scored[:top_k]



def build_context_pack(
    *,
    candidates: list[dict[str, Any]],
    min_score: float,
    max_chunks: int,
    max_chars: int,
) -> dict[str, Any]:
    selected: list[dict[str, Any]] = []
    total_chars = 0
    rejected_low_score = 0

    for item in candidates:
        if item["score"] < min_score:
            rejected_low_score += 1
            continue

        text = item["text"].strip()
        next_size = len(text)
        if len(selected) >= max_chunks:
            break
        if total_chars + next_size > max_chars:
            continue

        selected.append(item)
        total_chars += next_size

    return {
        "chunks": selected,
        "total_chars": total_chars,
        "rejected_low_score": rejected_low_score,
    }

from __future__ import annotations

from dataclasses import dataclass
from typing import Any

from retriever import build_context_pack, retrieve_candidates


class StopRun(Exception):
    def __init__(self, reason: str):
        super().__init__(reason)
        self.reason = reason


@dataclass(frozen=True)
class Budget:
    max_query_chars: int = 240
    max_top_k: int = 6
    max_context_chunks: int = 3
    max_context_chars: int = 2200
    min_chunk_score: float = 0.2
    max_seconds: int = 20



def validate_retrieval_intent(
    raw: Any,
    *,
    allowed_sources_policy: set[str],
    max_top_k: int,
) -> dict[str, Any]:
    if not isinstance(raw, dict):
        raise StopRun("invalid_intent:not_object")

    if raw.get("kind") != "retrieve":
        raise StopRun("invalid_intent:kind")

    query = raw.get("query")
    if not isinstance(query, str) or not query.strip():
        raise StopRun("invalid_intent:query")

    top_k = raw.get("top_k", 4)
    if not isinstance(top_k, int) or not (1 <= top_k <= max_top_k):
        raise StopRun("invalid_intent:top_k")

    sources_raw = raw.get("sources")
    normalized_sources: list[str] = []
    if sources_raw is not None:
        if not isinstance(sources_raw, list) or not sources_raw:
            raise StopRun("invalid_intent:sources")
        for source in sources_raw:
            if not isinstance(source, str) or not source.strip():
                raise StopRun("invalid_intent:source_item")
            source_name = source.strip()
            if source_name not in allowed_sources_policy:
                raise StopRun(f"invalid_intent:source_not_allowed:{source_name}")
            normalized_sources.append(source_name)

    # Ignore unknown keys and keep only contract fields.
    payload = {
        "kind": "retrieve",
        "query": query.strip(),
        "top_k": top_k,
    }
    if normalized_sources:
        payload["sources"] = normalized_sources
    return payload


class RetrievalGateway:
    def __init__(
        self,
        *,
        documents: list[dict[str, Any]],
        budget: Budget,
        allow_execution_sources: set[str],
    ):
        self.documents = documents
        self.budget = budget
        self.allow_execution_sources = set(allow_execution_sources)

    def run(self, intent: dict[str, Any]) -> dict[str, Any]:
        query = intent["query"]
        if len(query) > self.budget.max_query_chars:
            raise StopRun("invalid_intent:query_too_long")

        requested_sources = set(intent.get("sources") or self.allow_execution_sources)
        denied = sorted(requested_sources - self.allow_execution_sources)
        if denied:
            raise StopRun(f"source_denied:{denied[0]}")

        candidates = retrieve_candidates(
            query=query,
            documents=self.documents,
            top_k=intent["top_k"],
            allowed_sources=requested_sources,
        )

        context_pack = build_context_pack(
            candidates=candidates,
            min_score=self.budget.min_chunk_score,
            max_chunks=self.budget.max_context_chunks,
            max_chars=self.budget.max_context_chars,
        )

        return {
            "query": query,
            "requested_sources": sorted(requested_sources),
            "candidates": candidates,
            "context_chunks": context_pack["chunks"],
            "context_total_chars": context_pack["total_chars"],
            "rejected_low_score": context_pack["rejected_low_score"],
        }

from __future__ import annotations

import json
import os
from typing import Any

from openai import APIConnectionError, APITimeoutError, OpenAI

MODEL = os.getenv("OPENAI_MODEL", "gpt-4.1-mini")
LLM_TIMEOUT_SECONDS = float(os.getenv("OPENAI_TIMEOUT_SECONDS", "60"))


class LLMTimeout(Exception):
    pass


class LLMEmpty(Exception):
    pass


class LLMInvalid(Exception):
    pass


RETRIEVAL_SYSTEM_PROMPT = """
You are a retrieval planner for a RAG system.
Return exactly one JSON object in this shape:
{
  "kind": "retrieve",
  "query": "short retrieval query",
  "top_k": 4
}

Optional key:
- "sources": ["support_policy", "security_policy"]

Rules:
- Use only sources from available_sources.
- Keep query compact and factual.
- top_k must be between 1 and 6.
- Prefer omitting "sources" unless the question explicitly requires a specific policy domain.
- Do not output markdown or extra keys.
""".strip()

ANSWER_SYSTEM_PROMPT = """
You are a support assistant.
Return exactly one JSON object with this shape:
{
  "answer": "grounded answer in English",
  "citations": ["doc_id_1", "doc_id_2"]
}

Rules:
- Use only facts from provided context_chunks.
- Keep the answer concise and actionable.
- Include at least one citation.
- All citations must be doc_ids from context_chunks.
- Do not output markdown or extra keys.
""".strip()



def _get_client() -> OpenAI:
    api_key = os.getenv("OPENAI_API_KEY")
    if not api_key:
        raise EnvironmentError(
            "OPENAI_API_KEY is not set. Run: export OPENAI_API_KEY='sk-...'"
        )
    return OpenAI(api_key=api_key)



def plan_retrieval_intent(*, question: str, available_sources: list[str]) -> dict[str, Any]:
    payload = {
        "question": question,
        "available_sources": available_sources,
    }

    client = _get_client()
    try:
        completion = client.chat.completions.create(
            model=MODEL,
            temperature=0,
            timeout=LLM_TIMEOUT_SECONDS,
            response_format={"type": "json_object"},
            messages=[
                {"role": "system", "content": RETRIEVAL_SYSTEM_PROMPT},
                {"role": "user", "content": json.dumps(payload, ensure_ascii=False)},
            ],
        )
    except (APITimeoutError, APIConnectionError) as exc:
        raise LLMTimeout("llm_timeout") from exc

    text = completion.choices[0].message.content or "{}"
    try:
        return json.loads(text)
    except json.JSONDecodeError:
        return {"kind": "invalid", "raw": text}



def compose_grounded_answer(
    *,
    question: str,
    context_chunks: list[dict[str, Any]],
) -> dict[str, Any]:
    payload = {
        "question": question,
        "context_chunks": [
            {
                "doc_id": item.get("doc_id"),
                "title": item.get("title"),
                "section": item.get("section"),
                "updated_at": item.get("updated_at"),
                "text": item.get("text"),
            }
            for item in context_chunks
        ],
    }

    client = _get_client()
    try:
        completion = client.chat.completions.create(
            model=MODEL,
            temperature=0,
            timeout=LLM_TIMEOUT_SECONDS,
            response_format={"type": "json_object"},
            messages=[
                {"role": "system", "content": ANSWER_SYSTEM_PROMPT},
                {"role": "user", "content": json.dumps(payload, ensure_ascii=False)},
            ],
        )
    except (APITimeoutError, APIConnectionError) as exc:
        raise LLMTimeout("llm_timeout") from exc

    text = completion.choices[0].message.content or "{}"
    try:
        data = json.loads(text)
    except json.JSONDecodeError as exc:
        raise LLMInvalid("llm_invalid_json") from exc

    if not isinstance(data, dict):
        raise LLMInvalid("llm_invalid_json")

    answer = data.get("answer")
    citations = data.get("citations")

    if not isinstance(answer, str):
        raise LLMInvalid("llm_invalid_schema")
    if not answer.strip():
        raise LLMEmpty("llm_empty")

    if not isinstance(citations, list):
        raise LLMInvalid("llm_invalid_schema")

    normalized_citations: list[str] = []
    for item in citations:
        if not isinstance(item, str):
            raise LLMInvalid("llm_invalid_schema")
        value = item.strip()
        if value:
            normalized_citations.append(value)

    return {
        "answer": answer.strip(),
        "citations": normalized_citations,
    }

from __future__ import annotations

import json
import time
from typing import Any

from gateway import Budget, RetrievalGateway, StopRun, validate_retrieval_intent
from kb import KB_DOCUMENTS
from llm import LLMEmpty, LLMInvalid, LLMTimeout, compose_grounded_answer, plan_retrieval_intent

QUESTION = "What SLA applies to enterprise plan and what is P1 first response target?"

BUDGET = Budget(
    max_query_chars=240,
    max_top_k=6,
    max_context_chunks=3,
    max_context_chars=2200,
    min_chunk_score=0.2,
    max_seconds=20,
)

ALLOWED_SOURCES_POLICY = {
    "support_policy",
    "security_policy",
    "billing_policy",
}

SECURITY_SOURCE_RUNTIME_ENABLED = True
ALLOWED_SOURCES_EXECUTION = (
    {"support_policy", "security_policy", "billing_policy"}
    if SECURITY_SOURCE_RUNTIME_ENABLED
    else {"support_policy", "billing_policy"}
)
# Set SECURITY_SOURCE_RUNTIME_ENABLED=False to observe source_denied:security_policy.



def _shorten(text: str, *, limit: int = 280) -> str:
    text = (text or "").strip()
    if len(text) <= limit:
        return text
    return text[: limit - 3].rstrip() + "..."



def _validate_citations_from_context(
    context_chunks: list[dict[str, Any]],
    citations: list[str],
) -> tuple[list[str], list[dict[str, Any]], list[str], list[str]]:
    by_id: dict[str, dict[str, Any]] = {
        str(chunk["doc_id"]): chunk
        for chunk in context_chunks
        if chunk.get("doc_id")
    }

    normalized: list[str] = []
    seen: set[str] = set()
    for citation in citations:
        value = str(citation).strip()
        if not value or value in seen:
            continue
        seen.add(value)
        normalized.append(value)

    invalid = sorted([doc_id for doc_id in normalized if doc_id not in by_id])

    valid_doc_ids: list[str] = []
    citation_details: list[dict[str, Any]] = []
    for doc_id in normalized:
        chunk = by_id.get(doc_id)
        if not chunk:
            continue
        valid_doc_ids.append(doc_id)
        citation_details.append(
            {
                "doc_id": chunk["doc_id"],
                "title": chunk["title"],
                "section": chunk["section"],
                "updated_at": chunk["updated_at"],
                "source": chunk["source"],
                "score": chunk["score"],
            }
        )

    return valid_doc_ids, citation_details, invalid, sorted(by_id.keys())



def run_rag(question: str) -> dict[str, Any]:
    started = time.monotonic()
    trace: list[dict[str, Any]] = []
    history: list[dict[str, Any]] = []

    gateway = RetrievalGateway(
        documents=KB_DOCUMENTS,
        budget=BUDGET,
        allow_execution_sources=ALLOWED_SOURCES_EXECUTION,
    )

    try:
        raw_intent = plan_retrieval_intent(
            question=question,
            available_sources=sorted(ALLOWED_SOURCES_POLICY),
        )
    except LLMTimeout:
        return {
            "status": "stopped",
            "stop_reason": "llm_timeout",
            "phase": "plan",
            "trace": trace,
            "history": history,
        }

    try:
        intent = validate_retrieval_intent(
            raw_intent,
            allowed_sources_policy=ALLOWED_SOURCES_POLICY,
            max_top_k=BUDGET.max_top_k,
        )
    except StopRun as exc:
        return {
            "status": "stopped",
            "stop_reason": exc.reason,
            "phase": "plan",
            "raw_intent": raw_intent,
            "trace": trace,
            "history": history,
        }

    if (time.monotonic() - started) > BUDGET.max_seconds:
        return {
            "status": "stopped",
            "stop_reason": "max_seconds",
            "phase": "retrieve",
            "trace": trace,
            "history": history,
        }

    try:
        retrieval = gateway.run(intent)
    except StopRun as exc:
        return {
            "status": "stopped",
            "stop_reason": exc.reason,
            "phase": "retrieve",
            "intent": intent,
            "trace": trace,
            "history": history,
        }

    trace.append(
        {
            "step": 1,
            "phase": "retrieve",
            "query": retrieval["query"],
            "requested_sources": retrieval["requested_sources"],
            "candidates": len(retrieval["candidates"]),
            "context_chunks": len(retrieval["context_chunks"]),
            "rejected_low_score": retrieval["rejected_low_score"],
            "ok": True,
        }
    )

    history.append(
        {
            "step": 1,
            "intent": intent,
            "retrieval": {
                "candidates": [
                    {
                        "doc_id": item["doc_id"],
                        "source": item["source"],
                        "score": item["score"],
                    }
                    for item in retrieval["candidates"]
                ],
                "context_chunks": [item["doc_id"] for item in retrieval["context_chunks"]],
            },
        }
    )

    if not retrieval["context_chunks"]:
        fallback_answer = (
            "I could not find enough grounded evidence in approved sources. "
            "Please clarify the plan (enterprise/standard) or provide a policy document link."
        )
        trace.append(
            {
                "step": 2,
                "phase": "fallback",
                "reason": "no_grounded_context",
                "ok": True,
            }
        )
        history.append(
            {
                "step": 2,
                "action": "fallback",
                "answer": fallback_answer,
            }
        )
        return {
            "status": "ok",
            "stop_reason": "success",
            "outcome": "clarify",
            "answer": fallback_answer,
            "citations": [],
            "citation_details": [],
            "trace": trace,
            "history": history,
        }

    if (time.monotonic() - started) > BUDGET.max_seconds:
        return {
            "status": "stopped",
            "stop_reason": "max_seconds",
            "phase": "generate",
            "trace": trace,
            "history": history,
        }

    try:
        final = compose_grounded_answer(
            question=question,
            context_chunks=retrieval["context_chunks"],
        )
    except LLMTimeout:
        return {
            "status": "stopped",
            "stop_reason": "llm_timeout",
            "phase": "generate",
            "trace": trace,
            "history": history,
        }
    except LLMInvalid as exc:
        return {
            "status": "stopped",
            "stop_reason": exc.args[0],
            "phase": "generate",
            "trace": trace,
            "history": history,
        }
    except LLMEmpty:
        return {
            "status": "stopped",
            "stop_reason": "llm_empty",
            "phase": "generate",
            "trace": trace,
            "history": history,
        }

    citations, citation_details, invalid_citations, context_doc_ids = _validate_citations_from_context(
        retrieval["context_chunks"],
        final["citations"],
    )
    if invalid_citations:
        return {
            "status": "stopped",
            "stop_reason": "invalid_answer:citations_out_of_context",
            "phase": "generate",
            "invalid_citations": invalid_citations,
            "context_doc_ids": context_doc_ids,
            "trace": trace,
            "history": history,
        }
    if len(citations) < 1:
        return {
            "status": "stopped",
            "stop_reason": "invalid_answer:missing_citations",
            "phase": "generate",
            "trace": trace,
            "history": history,
        }

    trace.append(
        {
            "step": 2,
            "phase": "generate",
            "citation_count": len(citations),
            "ok": True,
        }
    )

    history.append(
        {
            "step": 2,
            "action": "compose_grounded_answer",
            "answer": _shorten(final["answer"]),
            "citations": citations,
        }
    )

    return {
        "status": "ok",
        "stop_reason": "success",
        "outcome": "grounded_answer",
        "answer": final["answer"],
        "citations": citations,
        "citation_details": citation_details,
        "trace": trace,
        "history": history,
    }



def main() -> None:
    result = run_rag(QUESTION)
    print(json.dumps(result, indent=2, ensure_ascii=False))


if __name__ == "__main__":
    main()

openai==2.21.0

{
  "status": "ok",
  "stop_reason": "success",
  "outcome": "grounded_answer",
  "answer": "The Enterprise plan includes a 99.95% monthly uptime SLA. For P1 incidents, the first response target is 15 minutes, available 24/7.",
  "citations": ["doc_sla_enterprise_v3"],
  "citation_details": [
    {
      "doc_id": "doc_sla_enterprise_v3",
      "title": "Support Policy",
      "section": "Enterprise SLA",
      "updated_at": "2026-01-15",
      "source": "support_policy",
      "score": 1.0
    }
  ],
  "trace": [
    {
      "step": 1,
      "phase": "retrieve",
      "query": "SLA for enterprise plan and P1 first response target",
      "requested_sources": ["support_policy"],
      "candidates": 2,
      "context_chunks": 2,
      "rejected_low_score": 0,
      "ok": true
    },
    {
      "step": 2,
      "phase": "generate",
      "citation_count": 1,
      "ok": true
    }
  ],
  "history": [
    {
      "step": 1,
      "intent": {"kind": "retrieve", "query": "SLA for enterprise plan and P1 first response target", "top_k": 4, "sources": ["support_policy"]},
      "retrieval": {
        "candidates": [
          {"doc_id": "doc_sla_enterprise_v3", "source": "support_policy", "score": 1.0},
          {"doc_id": "doc_sla_standard_v2", "source": "support_policy", "score": 1.0}
        ],
        "context_chunks": ["doc_sla_enterprise_v3", "doc_sla_standard_v2"]
      }
    },
    {
      "step": 2,
      "action": "compose_grounded_answer",
      "answer": "The Enterprise plan includes a 99.95% monthly uptime SLA. For P1 incidents, the first response target is 15 minutes, available 24/7.",
      "citations": ["doc_sla_enterprise_v3"]
    }
  ]
}