"""The MCP gate for exposing OKF bundles (capability loop, step 3).

One command, one exit code. It asks whether a bundle can be reached over the
Model Context Protocol in two shapes -- one server in front of ONE bundle, and
one server that knows no bundle by name -- and it measures the thing the
operator actually asked about: what has to be rebuilt when a bundle is rebuilt,
and whether a stale artefact refuses out loud or answers quietly.

WRITTEN RED, before any capability. Nothing in this module serves a bundle,
ranks a concept or writes a skill; it only measures. The architecture choice --
one-to-one, one-to-many, skill, MCP, or both -- is the operator's, and this
file exists so that choice is made on numbers.

THE SERVER IS A SUBPROCESS AND NEVER AN IMPORT. Every row below speaks
newline-delimited JSON-RPC over the server's stdin/stdout, starting with the
`initialize` handshake. Importing the server's functions and calling them would
measure the functions; the thing a client meets is the process, its framing and
its error envelope, and those are what break.

DENOMINATORS DO NOT COME FROM THE RUN. `REQUIRED_TOOLS`, `DRILL_ARTEFACTS`,
`DISCOVERY_CHECKS`, `CROSS_CHECKS` and `HOSTILE_CASES` are pinned here. A row
that counted whatever the server happened to offer would go green by offering
less -- the defect this repository has already met once, in the retrieval
gate's rows 2 and 3.

THE QUESTION SET IS AN INPUT, NEVER A CONSTANT HERE. This repository is public
and the graded set names a consumer's documents, so row 2 takes a path plus the
freeze file that pins it, verifies the sha256 itself, and stays RED with a
stated reason when it is not supplied or does not match. What IS committed is
the synthetic corpus this module generates, whose subject matter is invented
here and names no real document.

SILENT IS RED REGARDLESS (row 3). An artefact that has gone stale may refuse,
and may be inherently incapable of going stale. It may not answer as though
nothing happened: a confident answer from yesterday's bundle is the one failure
mode a consumer cannot detect from the outside.
"""

from __future__ import annotations

import argparse
import hashlib
import json
import os
import subprocess
import sys
import tempfile
import threading
import time
from collections.abc import Iterator, Mapping, Sequence
from contextlib import contextmanager, suppress
from dataclasses import dataclass, field
from pathlib import Path
from typing import Any

TOOLS = Path(__file__).resolve().parent
REPO = TOOLS.parent
if str(REPO / "src") not in sys.path:
    sys.path.insert(0, str(REPO / "src"))

GREEN = "GREEN"
RED = "RED"

SERVER_MODULE = "llm_ingestion_okf.mcp_server"

# The protocol revision this gate speaks. A server answering `initialize` with
# a different one is not a finding by itself -- the spec allows a server to
# name the revision it supports -- but the handshake must complete.
PROTOCOL_VERSION = "2025-06-18"

# The minimum tool set per variant, with the reason each one exists. Pinned
# here so a server cannot pass row 1 by shipping fewer tools.
REQUIRED_TOOLS: Mapping[str, tuple[str, ...]] = {
    # A server in front of one bundle still has to say WHICH bundle, or an
    # answer cannot be attributed; and it has to hand over a concept's bytes,
    # because a ranked cut is a selection and row 2 asks about presence.
    "one-to-one": ("okf_describe", "okf_ask", "okf_fetch"),
    # A server that knows no bundle by name needs one more: the discovery
    # call. Everything else takes the bundle as an argument.
    "one-to-many": ("okf_list", "okf_describe", "okf_ask", "okf_fetch"),
}

# Every tool answer must carry both, or an arm cannot fill the answer contract:
# which bundle the claim comes from, and which concept inside it.
BUNDLE_KEY = "bundle_id"
SOURCE_KEY = "sources"

# Row 3 measures four artefact classes, not two. The operator's question was
# about maintenance, and the skill is the incumbent -- comparing MCP against
# nothing would answer half of it.
DRILL_ARTEFACTS: tuple[str, ...] = (
    "mcp-one-to-one",
    "mcp-one-to-many",
    "skill-one-to-one",
    "skill-one-to-many",
)

DISCOVERY_CHECKS: tuple[str, ...] = ("list", "describe", "fetch")
DISCOVERY_BUNDLES = 3

CROSS_CHECKS: tuple[str, ...] = (
    "both-bundles-named",
    "both-sources-carried",
    "documented-sequence",
)

HOSTILE_CASES: tuple[str, ...] = (
    "traversal-in-bundle-id",
    "traversal-in-concept-id",
    "symlink-out-of-root",
    "broken-manifest",
    "oversized-concept",
    "unknown-bundle-id",
)

# A concept large enough that reading it whole is a decision rather than an
# accident. The order names 10 MB; the gate writes exactly that.
OVERSIZED_BYTES = 10 * 1024 * 1024

CALL_TIMEOUT = 30.0


class GateUsage(Exception):
    """Wrong input to the gate itself: exit 2, never a red row."""


class RpcError(Exception):
    """The server answered with a JSON-RPC error. That is a LOUD refusal and
    several rows want exactly this."""

    def __init__(self, code: int, message: str) -> None:
        super().__init__(f"{code}: {message}")
        self.code = code
        self.message = message


class ServerGone(Exception):
    """The process died, or said nothing within the timeout."""


# --------------------------------------------------------------------------
# A JSON-RPC stdio client, written narrowly on purpose.
# --------------------------------------------------------------------------


class Stdio:
    """Newline-delimited JSON-RPC 2.0 over a child process's stdio.

    Hand-written because the gate must not share a code path with the thing it
    judges: a client built from the server's own framing helpers would agree
    with the server by construction.
    """

    def __init__(self, argv: Sequence[str], *, cwd: Path | None = None) -> None:
        env = dict(os.environ)
        env["PYTHONPATH"] = os.pathsep.join(
            [str(REPO / "src"), *([env["PYTHONPATH"]] if env.get("PYTHONPATH") else [])]
        )
        self.proc = subprocess.Popen(
            list(argv),
            stdin=subprocess.PIPE,
            stdout=subprocess.PIPE,
            stderr=subprocess.PIPE,
            cwd=str(cwd) if cwd else None,
            env=env,
            text=True,
            encoding="utf-8",
            bufsize=1,
        )
        self._next_id = 0
        self._stderr: list[str] = []
        self._pump = threading.Thread(target=self._drain_stderr, daemon=True)
        self._pump.start()

    def _drain_stderr(self) -> None:
        assert self.proc.stderr is not None
        for line in self.proc.stderr:
            self._stderr.append(line.rstrip("\n"))

    @property
    def stderr_tail(self) -> str:
        return " | ".join(self._stderr[-4:])

    def _send(self, message: Mapping[str, Any]) -> None:
        assert self.proc.stdin is not None
        if self.proc.poll() is not None:
            raise ServerGone(f"exited {self.proc.returncode}: {self.stderr_tail}")
        try:
            self.proc.stdin.write(json.dumps(message, ensure_ascii=False) + "\n")
            self.proc.stdin.flush()
        except (BrokenPipeError, ValueError) as error:  # pragma: no cover - race
            raise ServerGone(f"{error}: {self.stderr_tail}") from error

    def _read(self, timeout: float) -> dict[str, Any]:
        assert self.proc.stdout is not None
        result: list[str] = []

        def reader() -> None:
            line = self.proc.stdout.readline()  # type: ignore[union-attr]
            result.append(line)

        thread = threading.Thread(target=reader, daemon=True)
        thread.start()
        thread.join(timeout)
        if thread.is_alive():
            raise ServerGone(f"no answer within {timeout}s: {self.stderr_tail}")
        if not result or not result[0]:
            raise ServerGone(f"stdout closed: {self.stderr_tail}")
        try:
            parsed = json.loads(result[0])
        except json.JSONDecodeError as error:
            raise ServerGone(f"not JSON: {result[0][:120]!r}") from error
        if not isinstance(parsed, dict):
            raise ServerGone(f"not a JSON-RPC object: {result[0][:120]!r}")
        return parsed

    def request(
        self, method: str, params: Mapping[str, Any] | None = None, *, timeout: float = CALL_TIMEOUT
    ) -> dict[str, Any]:
        self._next_id += 1
        message: dict[str, Any] = {"jsonrpc": "2.0", "id": self._next_id, "method": method}
        if params is not None:
            message["params"] = params
        self._send(message)
        deadline = time.monotonic() + timeout
        while True:
            answer = self._read(max(0.1, deadline - time.monotonic()))
            if "id" not in answer:  # a notification from the server; skip it
                continue
            if answer.get("id") != self._next_id:
                continue
            if "error" in answer:
                error = answer["error"]
                raise RpcError(int(error.get("code", 0)), str(error.get("message", "")))
            payload = answer.get("result")
            if not isinstance(payload, dict):
                raise ServerGone(f"result is not an object: {answer!r}")
            return payload

    def notify(self, method: str, params: Mapping[str, Any] | None = None) -> None:
        message: dict[str, Any] = {"jsonrpc": "2.0", "method": method}
        if params is not None:
            message["params"] = params
        self._send(message)

    def handshake(self) -> dict[str, Any]:
        result = self.request(
            "initialize",
            {
                "protocolVersion": PROTOCOL_VERSION,
                "capabilities": {},
                "clientInfo": {"name": "okf-mcp-gate", "version": "1"},
            },
        )
        self.notify("notifications/initialized")
        return result

    def tool_names(self) -> tuple[str, ...]:
        listed = self.request("tools/list").get("tools", [])
        return tuple(str(tool.get("name", "")) for tool in listed if isinstance(tool, dict))

    def call(self, name: str, arguments: Mapping[str, Any]) -> dict[str, Any]:
        """One `tools/call`, unwrapped to the object the tool returned.

        A tool that fails INSIDE the envelope (`isError: true`) is raised as an
        RpcError too: to a client the two are the same refusal, and a gate that
        treated one as loud and the other as silent would be scoring the
        server's transport taste.
        """
        result = self.request("tools/call", {"name": name, "arguments": dict(arguments)})
        text = ""
        for block in result.get("content", []) or []:
            if isinstance(block, dict) and block.get("type") == "text":
                text = str(block.get("text", ""))
                break
        if result.get("isError"):
            raise RpcError(-32000, text or "isError")
        structured = result.get("structuredContent")
        if isinstance(structured, dict):
            return structured
        try:
            parsed = json.loads(text)
        except json.JSONDecodeError as error:
            raise ServerGone(f"tool {name} returned no readable object: {text[:120]!r}") from error
        if not isinstance(parsed, dict):
            raise ServerGone(f"tool {name} returned {type(parsed).__name__}, not an object")
        return parsed

    def close(self) -> None:
        with suppress(Exception):
            assert self.proc.stdin is not None
            self.proc.stdin.close()
        try:
            self.proc.wait(timeout=5)
        except subprocess.TimeoutExpired:  # pragma: no cover - only on a hang
            self.proc.kill()
            self.proc.wait(timeout=5)


@contextmanager
def server(argv: Sequence[str]) -> Iterator[Stdio]:
    client = Stdio(argv)
    try:
        yield client
    finally:
        client.close()


def variant_argv(variant: str, target: Path) -> list[str]:
    flag = "--bundle" if variant == "one-to-one" else "--root"
    return [sys.executable, "-m", SERVER_MODULE, flag, str(target)]


def server_exists() -> tuple[bool, str]:
    """Measured, not assumed: ask the interpreter to import the module.

    `0 of N` is a measurement only when the query behind it is shown, so the
    reason string carries the interpreter's own words.
    """
    probe = subprocess.run(
        [sys.executable, "-c", f"import {SERVER_MODULE}"],
        capture_output=True,
        text=True,
        env={**os.environ, "PYTHONPATH": str(REPO / "src")},
        cwd=str(REPO),
        check=False,
    )
    if probe.returncode == 0:
        return True, "module imports"
    tail = (probe.stderr or "").strip().splitlines()
    return False, tail[-1] if tail else f"exit {probe.returncode}"


# --------------------------------------------------------------------------
# Synthetic bundles. Invented subject matter, no real document named.
# --------------------------------------------------------------------------

CONCEPT = """---
type: reference
title: {title}
source_file: {source}
ingested_at: 2026-01-01T00:00:00Z
generated: true
sources: [{{ resource: {source}, title: {source} }}]
adjudication: proposed
bundle_id: {bundle_id}
segment_id: {segment}
source_lines: [1, 4]
---

## {title}

{body}
"""


def write_bundle(root: Path, bundle_id: str, concepts: Sequence[tuple[str, str, str]]) -> Path:
    """`concepts` is (slug, title, body). One flat directory, one index."""
    root.mkdir(parents=True, exist_ok=True)
    lines = [
        "---",
        "okf_version: 0.2",
        f"bundle_id: {bundle_id}",
        "---",
        "",
    ]
    for position, (slug, title, body) in enumerate(concepts, start=1):
        (root / f"{slug}.md").write_text(
            CONCEPT.format(
                title=title,
                source=f"{slug}.txt",
                bundle_id=bundle_id,
                segment=f"s{position}",
                body=body,
            ),
            encoding="utf-8",
        )
        lines.append(f"- [{title}]({slug}.md) — adjudication: proposed")
    (root / "index.md").write_text("\n".join(lines) + "\n", encoding="utf-8")
    return root


def corpus(scratch: Path) -> dict[str, Path]:
    """Two bundles that share no vocabulary, so a cross-bundle answer cannot
    be produced by one of them alone."""
    bridges = write_bundle(
        scratch / "bundles" / "bridge-notes",
        "bridge-notes",
        [
            ("spennvidde", "Spennvidde for gangbru", "En gangbru med spennvidde 24 meter."),
            ("rekkverk", "Rekkverk paa gangbru", "Rekkverket skal vaere 1,2 meter hoeyt."),
        ],
    )
    kitchens = write_bundle(
        scratch / "bundles" / "kitchen-notes",
        "kitchen-notes",
        [
            ("surdeig", "Surdeig og heving", "Surdeigen hever i 14 timer ved 22 grader."),
            ("ovn", "Ovnstemperatur", "Ovnen forvarmes til 250 grader."),
        ],
    )
    return {"bridge-notes": bridges, "kitchen-notes": kitchens}


# --------------------------------------------------------------------------
# Rows
# --------------------------------------------------------------------------


@dataclass
class Row:
    number: int
    name: str
    k: int
    m: int
    status: str
    reason: str
    details: list[str] = field(default_factory=list)

    @property
    def fails(self) -> bool:
        return self.status != GREEN

    def to_json(self) -> dict[str, Any]:
        return {
            "row": self.number,
            "name": self.name,
            "k": self.k,
            "m": self.m,
            "status": self.status,
            "reason": self.reason,
            "details": self.details,
        }


def _row(number: int, name: str, k: int, m: int, reason: str, details: list[str]) -> Row:
    """`m == 0` is NEVER green: a row with nothing to count did not measure."""
    return Row(number, name, k, m, GREEN if m > 0 and k == m else RED, reason, details)


# Which keys an answer must carry, per tool. `okf_list` and `okf_describe`
# answer ABOUT a bundle; the other two answer FROM one, and an answer from a
# bundle without a concept id cannot be cited.
ANSWER_KEYS: Mapping[str, tuple[str, ...]] = {
    "okf_list": (BUNDLE_KEY,),
    "okf_describe": (BUNDLE_KEY,),
    "okf_ask": (BUNDLE_KEY, SOURCE_KEY),
    "okf_fetch": (BUNDLE_KEY, SOURCE_KEY),
}


def _bundle_ids(answer: Mapping[str, Any]) -> set[str]:
    """Every bundle id anywhere in the answer, at any depth.

    A `list` answer carries one id per bundle and an `ask` answer carries one
    per excerpt, so a rule reading only the top level would score the shapes
    rather than the contract.
    """
    found: set[str] = set()

    def walk(node: Any) -> None:
        if isinstance(node, Mapping):
            value = node.get(BUNDLE_KEY)
            if isinstance(value, str) and value:
                found.add(value)
            for child in node.values():
                walk(child)
        elif isinstance(node, (list, tuple)):
            for child in node:
                walk(child)

    walk(answer)
    return found


def _source_ids(answer: Mapping[str, Any]) -> set[str]:
    found: set[str] = set()

    def walk(node: Any) -> None:
        if isinstance(node, Mapping):
            for key in ("concept_id", "source_id"):
                value = node.get(key)
                if isinstance(value, str) and value:
                    found.add(value)
            for child in node.values():
                walk(child)
        elif isinstance(node, (list, tuple)):
            for child in node:
                walk(child)

    walk(answer)
    return found


def _probe_arguments(tool: str, bundle_id: str, concept_id: str, *, named: bool) -> dict[str, Any]:
    """One representative call per tool. `named` is False for the one-to-one
    variant, whose bundle is fixed at startup and takes no bundle argument."""
    bundle: dict[str, Any] = {BUNDLE_KEY: bundle_id} if named else {}
    if tool == "okf_list":
        return {}
    if tool == "okf_describe":
        return bundle
    if tool == "okf_ask":
        return {**bundle, "question": "spennvidde for gangbru"}
    return {**bundle, "concept_id": concept_id}


def _first_concept_id(client: Stdio, bundle_id: str, *, named: bool) -> str:
    answer = client.call("okf_describe", {BUNDLE_KEY: bundle_id} if named else {})
    for key in ("concepts", "concept_ids"):
        value = answer.get(key)
        if isinstance(value, list) and value:
            head = value[0]
            if isinstance(head, str):
                return head
            if isinstance(head, Mapping) and isinstance(head.get("concept_id"), str):
                return str(head["concept_id"])
    raise ServerGone("okf_describe named no concept, so okf_fetch has no argument")


def row_one(bundles: Mapping[str, Path], reachable: tuple[bool, str]) -> Row:
    """The handshake, the tool list, and one call per required tool.

    `m` is the pinned roster across both variants, so a server shipping three
    tools where four are required scores 3 of 7 rather than 3 of 3.
    """
    m = sum(len(names) for names in REQUIRED_TOOLS.values())
    details: list[str] = []
    if not reachable[0]:
        return _row(
            1,
            "protocol: initialize -> tools/list -> tools/call over stdio",
            0,
            m,
            f"`python -c 'import {SERVER_MODULE}'` fails: {reachable[1]}",
            [f"roster: {json.dumps(REQUIRED_TOOLS)}"],
        )
    k = 0
    for variant, required in REQUIRED_TOOLS.items():
        named = variant == "one-to-many"
        target = bundles["bridge-notes"] if not named else bundles["bridge-notes"].parent
        try:
            with server(variant_argv(variant, target)) as client:
                client.handshake()
                listed = set(client.tool_names())
                concept = ""
                with suppress(Exception):
                    concept = _first_concept_id(client, "bridge-notes", named=named)
                for tool in required:
                    if tool not in listed:
                        details.append(f"{variant}: {tool} not in tools/list")
                        continue
                    try:
                        answer = client.call(
                            tool, _probe_arguments(tool, "bridge-notes", concept, named=named)
                        )
                    except (RpcError, ServerGone) as error:
                        details.append(f"{variant}: {tool} did not answer: {error}")
                        continue
                    missing = []
                    if BUNDLE_KEY in ANSWER_KEYS[tool] and not _bundle_ids(answer):
                        missing.append(BUNDLE_KEY)
                    if SOURCE_KEY in ANSWER_KEYS[tool] and not _source_ids(answer):
                        missing.append("concept_id")
                    if missing:
                        details.append(f"{variant}: {tool} answered without {', '.join(missing)}")
                        continue
                    k += 1
        except (ServerGone, OSError) as error:
            details.append(f"{variant}: server did not start: {error}")
    return _row(
        1,
        "protocol: initialize -> tools/list -> tools/call over stdio",
        k,
        m,
        "every required tool answers over real stdio, carrying bundle id and concept id",
        details,
    )


@dataclass(frozen=True)
class AnchorSet:
    """A (bundle, anchor, quote) triple set, read from a frozen question file.

    The set is never committed here. `path` and `sha256` are the whole
    registration, and a set whose bytes moved is a usage error, not a red row:
    a gate that measured a moving set would be reporting on nothing.
    """

    label: str
    pairs: tuple[tuple[str, str, str], ...]
    version: int
    note: str


def read_anchor_set(questions: Path, freeze: Path, *, want_version: int) -> AnchorSet:
    if not questions.is_file():
        raise GateUsage(f"question set not found: {questions}")
    if not freeze.is_file():
        raise GateUsage(f"freeze file not found: {freeze}")
    frozen = json.loads(freeze.read_text(encoding="utf-8"))
    declared = frozen.get("sha256", {}).get(questions.name)
    measured = hashlib.sha256(questions.read_bytes()).hexdigest()
    version = int(frozen.get("versjon", 0))
    if declared != measured:
        raise GateUsage(
            f"{questions.name} is not the file {freeze.name} pins: "
            f"declared {declared}, measured {measured}"
        )
    if version < want_version:
        raise GateUsage(
            f"{freeze.name} declares version {version}; this gate was ordered "
            f"against version {want_version}"
        )
    document = json.loads(questions.read_text(encoding="utf-8"))
    pairs: dict[tuple[str, str], str] = {}
    for question in document.get("sporsmal", []):
        bundle = str(question.get("bundle") or question.get("kilde") or "")
        for atom in question.get("atomer", []) or []:
            anchor = atom.get("kilde_anker")
            quote = atom.get("kilde_sitat")
            if isinstance(anchor, str) and anchor:
                pairs.setdefault((bundle, anchor), str(quote or ""))
        for cite in question.get("must_cite", []) or []:
            if isinstance(cite, str) and cite:
                pairs.setdefault((bundle, cite), "")
            elif isinstance(cite, Mapping):
                anchor = cite.get("anker") or cite.get("kilde_anker")
                if isinstance(anchor, str) and anchor:
                    pairs.setdefault(
                        (str(cite.get("bundle") or bundle), anchor),
                        str(cite.get("kilde_sitat") or ""),
                    )
    return AnchorSet(
        label=f"{questions.parent.name}/{questions.name}",
        pairs=tuple((bundle, anchor, quote) for (bundle, anchor), quote in sorted(pairs.items())),
        version=version,
        note=str(frozen.get("merknad", ""))[:120],
    )


# The row-2 machinery's known-positive, over the synthetic corpus: four
# (bundle, anchor, quote) triples this file invented, whose text the tool
# surface must be able to hand back verbatim. Without it, a row reporting
# `0 of M` could be reporting that the lookup was never able to find anything.
SYNTHETIC_ANCHORS: tuple[tuple[str, str, str], ...] = (
    ("bridge-notes", "spennvidde", "En gangbru med spennvidde 24 meter."),
    ("bridge-notes", "rekkverk", "Rekkverket skal vaere 1,2 meter hoeyt."),
    ("kitchen-notes", "surdeig", "Surdeigen hever i 14 timer ved 22 grader."),
    ("kitchen-notes", "ovn", "Ovnen forvarmes til 250 grader."),
)


def _fetch_carries(client: Stdio, bundle_id: str, anchor: str, quote: str, *, named: bool) -> bool:
    """Can the surface hand back the text carrying `quote`, verbatim?

    This is a CEILING, never a hit rate: it asks whether the bytes are
    reachable at all, not whether a ranker would choose them.
    """
    arguments: dict[str, Any] = {"concept_id": anchor}
    if named:
        arguments[BUNDLE_KEY] = bundle_id
    try:
        answer = client.call("okf_fetch", arguments)
    except (RpcError, ServerGone):
        return False
    text = json.dumps(answer, ensure_ascii=False)
    return quote in text if quote else bool(_source_ids(answer))


def row_two(
    bundles: Mapping[str, Path], reachable: tuple[bool, str], anchors: AnchorSet | None
) -> Row:
    details: list[str] = []
    known_positive = 0
    if reachable[0]:
        root = next(iter(bundles.values())).parent
        try:
            with server(variant_argv("one-to-many", root)) as client:
                client.handshake()
                for bundle_id, anchor, quote in SYNTHETIC_ANCHORS:
                    if _fetch_carries(client, bundle_id, anchor, quote, named=True):
                        known_positive += 1
        except (ServerGone, OSError) as error:
            details.append(f"known-positive could not run: {error}")
    details.append(
        f"known-positive (synthetic, this file's own text): "
        f"{known_positive} of {len(SYNTHETIC_ANCHORS)} anchors fetched verbatim"
    )
    if anchors is None:
        return _row(
            2,
            "coverage ceiling: every anchor the frozen set points at, fetched verbatim",
            0,
            0,
            "no frozen question set supplied (--sett/--frys); the denominator is "
            "counted from that file at run time and is not known here",
            details,
        )
    m = len(anchors.pairs)
    details.append(
        f"set {anchors.label}, freeze version {anchors.version}, M = {m} (bundle, anchor) pairs"
    )
    if not reachable[0]:
        return _row(
            2,
            "coverage ceiling: every anchor the frozen set points at, fetched verbatim",
            0,
            m,
            f"`python -c 'import {SERVER_MODULE}'` fails: {reachable[1]}",
            details,
        )
    k = 0
    missing_bundles: set[str] = set()
    root = next(iter(bundles.values())).parent
    with server(variant_argv("one-to-many", root)) as client:
        client.handshake()
        served = {str(entry) for entry in _bundle_ids(client.call("okf_list", {}))}
        for bundle_id, anchor, quote in anchors.pairs:
            if bundle_id not in served:
                missing_bundles.add(bundle_id)
                continue
            if _fetch_carries(client, bundle_id, anchor, quote, named=True):
                k += 1
    if missing_bundles:
        details.append(
            "red for the BUNDLE, not the server: no bundle served under this root is "
            f"named {', '.join(sorted(missing_bundles))}"
        )
    return _row(
        2,
        "coverage ceiling: every anchor the frozen set points at, fetched verbatim",
        k,
        m,
        "the ceiling an arm can reach, per (bundle, anchor) pair",
        details,
    )


# --------------------------------------------------------------------------
# Row 3: the update drill. The operator's question, measured.
# --------------------------------------------------------------------------


@dataclass(frozen=True)
class DrillResult:
    artefact: str
    loud: bool
    recreate: tuple[str, ...]
    note: str


def _mutate(bundle: Path) -> None:
    """Change one concept, so the bundle's fingerprint moves."""
    target = sorted(p for p in bundle.rglob("*.md") if p.name != "index.md")[0]
    text = target.read_text(encoding="utf-8")
    target.write_text(
        text.rstrip("\n") + "\n\nEn setning som ikke sto her foer.\n", encoding="utf-8"
    )


def _drill_mcp(variant: str, bundle: Path, bundle_id: str) -> DrillResult:
    """A running server, a bundle rebuilt under it, and one question: does the
    answer move with the bytes, or does yesterday's answer keep coming?"""
    named = variant == "one-to-many"
    target = bundle if not named else bundle.parent
    try:
        with server(variant_argv(variant, target)) as client:
            client.handshake()
            before = client.call("okf_describe", {BUNDLE_KEY: bundle_id} if named else {})
            _mutate(bundle)
            after = client.call("okf_describe", {BUNDLE_KEY: bundle_id} if named else {})
            moved = before.get("ref") != after.get("ref")
            return DrillResult(
                f"mcp-{variant}",
                loud=bool(moved),
                recreate=(),
                note=(
                    "the identity moved with the bytes; nothing to recreate"
                    if moved
                    else f"SILENT: still reports ref {before.get('ref')!r} after the rebuild"
                ),
            )
    except (ServerGone, OSError, RpcError) as error:
        return DrillResult(f"mcp-{variant}", loud=False, recreate=(), note=f"did not run: {error}")


def _drill_skill_one_to_one(bundle: Path, scratch: Path) -> DrillResult:
    """Today's generated skill: it carries the fingerprint in its own prose, so
    a rebuilt bundle leaves it declaring an identity the payload no longer has.
    `okf check`'s `bundle_mismatch` is the loud refusal, and regenerating it is
    the cost."""
    try:
        from llm_ingestion_okf import consume as okf_consume
        from llm_ingestion_okf import contract_check, skill
    except ImportError as error:  # pragma: no cover - the package is always present
        return DrillResult("skill-one-to-one", loud=False, recreate=(), note=str(error))
    out = scratch / "skill-1-1"
    try:
        skill.generate(bundle, out=out, question="spennvidde for gangbru", force=True)
    except Exception as error:
        return DrillResult(
            "skill-one-to-one", loud=False, recreate=(), note=f"not generated: {error}"
        )
    declared = contract_check.skill_identity((out / "SKILL.md").read_text(encoding="utf-8"))
    _mutate(bundle)
    current = okf_consume.bundle_ref(bundle)
    loud = declared is not None and declared[1] != current
    return DrillResult(
        "skill-one-to-one",
        loud=loud,
        recreate=("okf skill <bundle> --out <skill dir> --force",),
        note=(
            f"declares ref {declared[1][:16] if declared else None}..., bundle now "
            f"{current[:16]}...; `okf check --skill` refuses (bundle_mismatch)"
            if loud
            else "the stale skill declares an identity no rule can compare"
        ),
    )


def _drill_skill_one_to_many(bundles: Mapping[str, Path], scratch: Path) -> DrillResult:
    """The candidate: one installable skill with no bundle-specific number in
    it, and the per-bundle numbers read at run time. Its staleness test is not
    a refusal -- it is that the artefact cannot go stale, which is stronger.

    Proved by a PROPERTY and not by reading it: the text generated for two
    bundles that share nothing must be byte-identical, and must carry neither
    bundle's id or ref.
    """
    try:
        from llm_ingestion_okf import consume as okf_consume
        from llm_ingestion_okf import skill
    except ImportError as error:  # pragma: no cover
        return DrillResult("skill-one-to-many", loud=False, recreate=(), note=str(error))
    render_generic = getattr(skill, "render_generic", None)
    if render_generic is None:
        return DrillResult(
            "skill-one-to-many",
            loud=False,
            recreate=(),
            note="`skill.render_generic` does not exist: the candidate has not been built",
        )
    first, second = (bundles["bridge-notes"], bundles["kitchen-notes"])
    text_first = render_generic()
    text_second = render_generic()
    identical = text_first == text_second
    leaked = [
        token
        for token in (
            "bridge-notes",
            "kitchen-notes",
            okf_consume.bundle_ref(first),
            okf_consume.bundle_ref(second),
        )
        if token in text_first
    ]
    (scratch / "skill-1-many").mkdir(parents=True, exist_ok=True)
    (scratch / "skill-1-many" / "SKILL.md").write_text(text_first, encoding="utf-8")
    return DrillResult(
        "skill-one-to-many",
        loud=identical and not leaked,
        recreate=(),
        note=(
            "carries no bundle id, no ref and no count, so a rebuild cannot make it wrong"
            if identical and not leaked
            else f"bundle-specific after all: {', '.join(leaked) or 'not reproducible'}"
        ),
    )


def row_three(scratch: Path) -> Row:
    """Scenario 1: one concept changes. Per artefact class -- does the stale
    copy refuse out loud, and what has to be made again?"""
    m = len(DRILL_ARTEFACTS)
    details: list[str] = []
    results: list[DrillResult] = []
    for artefact in DRILL_ARTEFACTS:
        stage = scratch / "drill" / artefact
        stage.mkdir(parents=True, exist_ok=True)
        bundles = corpus(stage)
        if artefact == "mcp-one-to-one":
            results.append(_drill_mcp("one-to-one", bundles["bridge-notes"], "bridge-notes"))
        elif artefact == "mcp-one-to-many":
            results.append(_drill_mcp("one-to-many", bundles["bridge-notes"], "bridge-notes"))
        elif artefact == "skill-one-to-one":
            results.append(_drill_skill_one_to_one(bundles["bridge-notes"], stage))
        else:
            results.append(_drill_skill_one_to_many(bundles, stage))
    for result in results:
        details.append(
            f"{result.artefact}: {'LOUD' if result.loud else 'SILENT/absent'}, "
            f"{len(result.recreate)} artefact(s) to recreate, "
            f"{len(result.recreate)} manual step(s) -- {result.note}"
        )
    return _row(
        3,
        "update drill 1: one concept changes; stale must refuse, never answer quietly",
        sum(1 for result in results if result.loud),
        m,
        "a silent stale answer is RED regardless of every other number",
        details,
    )


def row_four(scratch: Path) -> Row:
    """Scenario 2: three unknown bundles appear while the one-to-many server is
    RUNNING. No restart, no config, no code."""
    m = DISCOVERY_BUNDLES * len(DISCOVERY_CHECKS)
    stage = scratch / "discovery"
    stage.mkdir(parents=True, exist_ok=True)
    bundles = corpus(stage)
    root = bundles["bridge-notes"].parent
    newcomers = {
        "ferry-notes": ("avgang", "Avgangstider", "Fergen gaar hver time fra klokken 06."),
        "lichen-notes": ("vekst", "Vekstrate", "Lav vokser under en millimeter i aaret."),
        "sextant-notes": ("horisont", "Horisontmaaling", "Kimingen justeres for oeyehoeyde."),
    }
    details: list[str] = []
    k = 0
    try:
        with server(variant_argv("one-to-many", root)) as client:
            client.handshake()
            first = _bundle_ids(client.call("okf_list", {}))
            details.append(
                f"before: {len(first)} bundle(s) -- {', '.join(sorted(first)) or 'none'}"
            )
            for bundle_id, (slug, title, body) in newcomers.items():
                write_bundle(root / bundle_id, bundle_id, [(slug, title, body)])
            served = _bundle_ids(client.call("okf_list", {}))
            for bundle_id, (slug, _title, body) in newcomers.items():
                if bundle_id in served:
                    k += 1
                else:
                    details.append(f"{bundle_id}: not seen by a later `okf_list`")
                    continue
                try:
                    described = client.call("okf_describe", {BUNDLE_KEY: bundle_id})
                    if bundle_id in _bundle_ids(described):
                        k += 1
                    else:
                        details.append(f"{bundle_id}: okf_describe did not name it")
                except (RpcError, ServerGone) as error:
                    details.append(f"{bundle_id}: okf_describe refused: {error}")
                if _fetch_carries(client, bundle_id, slug, body, named=True):
                    k += 1
                else:
                    details.append(f"{bundle_id}: okf_fetch did not return its text")
    except (ServerGone, OSError, RpcError) as error:
        details.append(f"the running server could not be reached: {error}")
    return _row(
        4,
        "update drill 2: three unknown bundles appear while the server runs",
        k,
        m,
        "discovery happens per call; a restart, a config edit or a code change is RED",
        details,
    )


def row_five(scratch: Path) -> Row:
    """One documented call sequence that answers from two bundles at once, with
    both sources. An arm that cannot do this can only ever answer from one."""
    m = len(CROSS_CHECKS)
    stage = scratch / "cross"
    stage.mkdir(parents=True, exist_ok=True)
    bundles = corpus(stage)
    root = bundles["bridge-notes"].parent
    details: list[str] = []
    k = 0
    try:
        with server(variant_argv("one-to-many", root)) as client:
            client.handshake()
            calls = 0
            answer = client.call("okf_ask", {"question": "spennvidde og surdeig"})
            calls += 1
            named = _bundle_ids(answer)
            sources = _source_ids(answer)
            if {"bridge-notes", "kitchen-notes"} <= named:
                k += 1
            else:
                details.append(f"one answer named {sorted(named) or 'no bundle'}")
            if len(sources) >= 2:
                k += 1
            else:
                details.append(f"one answer carried {len(sources)} source id(s)")
            if calls == 1:
                k += 1
            details.append(
                f"documented sequence: {calls} call(s) -- okf_ask with no bundle argument"
            )
    except (ServerGone, OSError, RpcError) as error:
        details.append(f"cross-bundle answer could not be produced: {error}")
    return _row(
        5,
        "across bundles: one documented sequence, two bundles, both sources",
        k,
        m,
        "an answer spanning two bundles must carry both bundles' citations",
        details,
    )


def row_six(scratch: Path) -> Row:
    """Hostile input. Every case must be refused OUT LOUD, and nothing outside
    the served root may appear in any answer."""
    m = len(HOSTILE_CASES)
    stage = scratch / "hostile"
    stage.mkdir(parents=True, exist_ok=True)
    bundles = corpus(stage)
    root = bundles["bridge-notes"].parent

    outside = stage / "outside"
    outside.mkdir(parents=True, exist_ok=True)
    canary = "HEMMELIGHET-SOM-ALDRI-SKAL-LESES"
    write_bundle(outside / "secret-notes", "secret-notes", [("hemmelig", "Hemmelig", canary)])
    with suppress(OSError, NotImplementedError):
        (root / "linked-notes").symlink_to(outside / "secret-notes", target_is_directory=True)

    write_bundle(root / "broken-notes", "broken-notes", [("x", "X", "y")])
    (root / "broken-notes" / "index.md").write_bytes(b"\xff\xfe not a manifest at all\x00")

    huge = root / "bridge-notes" / "svulmende.md"
    huge.write_text(
        CONCEPT.format(
            title="Svulmende",
            source="svulmende.txt",
            bundle_id="bridge-notes",
            segment="s9",
            body="A" * OVERSIZED_BYTES,
        ),
        encoding="utf-8",
    )

    details: list[str] = []
    k = 0
    attempts: list[tuple[str, str, dict[str, Any]]] = [
        ("traversal-in-bundle-id", "okf_describe", {BUNDLE_KEY: "../outside/secret-notes"}),
        (
            "traversal-in-concept-id",
            "okf_fetch",
            {BUNDLE_KEY: "bridge-notes", "concept_id": "../../outside/secret-notes/hemmelig"},
        ),
        ("symlink-out-of-root", "okf_describe", {BUNDLE_KEY: "linked-notes"}),
        ("broken-manifest", "okf_describe", {BUNDLE_KEY: "broken-notes"}),
        ("oversized-concept", "okf_fetch", {BUNDLE_KEY: "bridge-notes", "concept_id": "svulmende"}),
        ("unknown-bundle-id", "okf_describe", {BUNDLE_KEY: "does-not-exist"}),
    ]
    try:
        with server(variant_argv("one-to-many", root)) as client:
            client.handshake()
            for case, tool, arguments in attempts:
                try:
                    answer = client.call(tool, arguments)
                except RpcError as error:
                    k += 1
                    details.append(f"{case}: refused loudly ({error})")
                    continue
                except ServerGone as error:
                    details.append(f"{case}: the server died instead of refusing ({error})")
                    continue
                body = json.dumps(answer, ensure_ascii=False)
                if canary in body:
                    details.append(f"{case}: READ OUTSIDE THE ROOT -- the canary is in the answer")
                else:
                    details.append(f"{case}: answered instead of refusing ({len(body)} bytes)")
    except (ServerGone, OSError) as error:
        details.append(f"the server could not be reached: {error}")
    return _row(
        6,
        "hostile input: traversal, symlink, broken manifest, 10 MB concept, unknown id",
        k,
        m,
        "every case refused out loud, and no byte from outside the served root in any answer",
        details,
    )


# --------------------------------------------------------------------------
# Verdict
# --------------------------------------------------------------------------

LIMITS: tuple[str, ...] = (
    "The gate measures a CEILING and a maintenance cost. It runs no arm, calls "
    "no model and ranks nothing: whether an arm answers well is a different "
    "question, asked by tools/okf_retrieval_gate.py.",
    "Row 2's denominator comes from the frozen question set at run time. "
    "Without --sett/--frys the row is red with m = 0, which is the honest "
    "shape: nothing was counted.",
    "Row 3 counts artefacts and manual steps INSIDE this machine. A consuming "
    "project that has installed a generated skill pays one more step per "
    "project, and that number is not measurable from here.",
    "The architecture choice is the operator's. These rows are the input to "
    "it, never the decision.",
)


def evaluate(
    scratch: Path,
    *,
    anchors: AnchorSet | None = None,
) -> list[Row]:
    reachable = server_exists()
    bundles = corpus(scratch / "base")
    return [
        row_one(bundles, reachable),
        row_two(bundles, reachable, anchors),
        row_three(scratch),
        row_four(scratch),
        row_five(scratch),
        row_six(scratch),
    ]


def render(rows: Sequence[Row]) -> str:
    lines = ["okf MCP gate", ""]
    for row in sorted(rows, key=lambda r: r.number):
        lines.append(f"{row.status:5}  row {row.number}: {row.name}")
        lines.append(f"       {row.k} of {row.m} -- {row.reason}")
        lines.extend(f"         - {detail}" for detail in row.details)
        lines.append("")
    failing = [row.number for row in sorted(rows, key=lambda r: r.number) if row.fails]
    lines.append(
        f"GATE {RED}: rows {', '.join(str(number) for number in failing)}"
        if failing
        else f"GATE {GREEN}"
    )
    lines.append("")
    lines.append("Limits:")
    lines.extend(f"  - {limit}" for limit in LIMITS)
    return "\n".join(lines) + "\n"


def main(argv: list[str] | None = None) -> int:
    parser = argparse.ArgumentParser(description=__doc__.split("\n", 1)[0])
    parser.add_argument("--json", action="store_true", help="emit the rows as JSON")
    parser.add_argument(
        "--sett",
        type=Path,
        help="the frozen graded question set row 2 counts its denominator from",
    )
    parser.add_argument(
        "--frys",
        type=Path,
        help="the freeze file that pins --sett by sha256 and declares its version",
    )
    parser.add_argument(
        "--sett-versjon",
        type=int,
        default=4,
        help="the freeze version this gate was ordered against (default 4)",
    )
    args = parser.parse_args(argv)
    try:
        anchors = (
            read_anchor_set(args.sett, args.frys, want_version=args.sett_versjon)
            if args.sett or args.frys
            else None
        )
        if (args.sett is None) != (args.frys is None):
            raise GateUsage("--sett and --frys are given together or not at all")
        with tempfile.TemporaryDirectory(prefix="okf-mcp-gate-") as scratch:
            rows = evaluate(Path(scratch), anchors=anchors)
    except GateUsage as error:
        print(f"okf-mcp-gate: {error}", file=sys.stderr)
        return 2
    # Broad on purpose, and the house pattern: a gate that dies with a
    # traceback must not be readable as a finding.
    except Exception as error:
        print(f"okf-mcp-gate: did not run: {type(error).__name__}: {error}", file=sys.stderr)
        return 2
    if args.json:
        print(
            json.dumps(
                {
                    "rows": [row.to_json() for row in sorted(rows, key=lambda r: r.number)],
                    "required_tools": {k: list(v) for k, v in REQUIRED_TOOLS.items()},
                    "limits": list(LIMITS),
                    "gate": RED if any(row.fails for row in rows) else GREEN,
                },
                indent=2,
                ensure_ascii=False,
            )
        )
    else:
        print(render(rows), end="")
    return 1 if any(row.fails for row in rows) else 0


if __name__ == "__main__":
    raise SystemExit(main())