source.py

"""Miner3-v9: fast Luna drafts with evidence-gated differential repair."""

import ast
import hashlib
import json
import os
import re
import resource
import signal
import subprocess
import sys
import tempfile
import time
from decimal import Decimal, InvalidOperation


_FORMAT = "miner3-evidence-gated-v9"
_PRIMARY = "openai/gpt-5.6-luna"
_TOOLS_MODEL = "openai/gpt-5.6-luna"
_DIVERSE = "google/gemini-3.6-flash"
_CONFIRM = "google/gemini-3.6-flash"
_EXPECTED_TASKS = 6
_OUTPUT_LIMIT = 4 * 1024 * 1024
_CASE_TIMEOUT_S = 7.0
_GENERATOR_TIMEOUT_S = 5.0
_PERF_GENERATOR_TIMEOUT_S = 8.0
_PERF_TIMEOUT_S = 7.0
_PERF_TARGET_S = 2.5
_PERF_SIZE = 200000
_MAX_EVIDENCE_INPUT = 16384
_MAX_EVIDENCE_OUTPUT = 4096
_CHILD_CPU_S = 8
_CHILD_AS_BYTES = 1 << 30
_CHILD_NPROC = 16
_CHILD_NOFILE = 32
_SIZES = (2, 3, 5, 8, 13, 21, 34, 40)
_MAX_TOOL_BYTES = 64 * 1024
_SAFE_IMPORTS = frozenset((
    "array", "bisect", "collections", "copy", "dataclasses", "decimal",
    "fractions", "functools", "heapq", "itertools", "math", "operator",
    "random", "re", "statistics", "string", "sys", "typing",
))
_BLOCKED_NAMES = frozenset((
    "__import__", "breakpoint", "compile", "delattr", "dir", "eval", "exec",
    "getattr", "globals", "help", "locals", "open", "setattr", "vars",
))
_BLOCKED_ATTRIBUTES = frozenset((
    "fork", "forkpty", "kill", "meta_path", "modules", "path", "path_hooks",
    "popen", "posix_spawn", "setprofile", "settrace", "spawn", "system",
))
_BLOCKED_TEXT = (
    "/dev", "/etc", "/proc", "/root", "/run", "openrouter", "hf_token",
    "hugging_face",
    "subprocess", "multiprocessing", "socket", "__import__",
)

_SAMPLE = re.compile(r"^Sample (Input|Output)\s*(\d+)\s*$", re.MULTILINE)
_FENCE = re.compile(r"```(?:python|py)?\s*\n(.*?)```", re.DOTALL | re.IGNORECASE)
_TOOLS = re.compile(r"```(oracle|generator)\s*\n(.*?)```", re.DOTALL | re.IGNORECASE)
_UNSAFE = re.compile(
    r"\b(?:subprocess|multiprocessing|socket)\b|"
    r"\bos\s*\.\s*(?:fork|forkpty|posix_spawn|system|popen)\b|"
    r"\bpty\s*\.\s*spawn\b",
    re.IGNORECASE,
)

_DRAFT_GUIDANCE = " ".join((
    "Derive the algorithm from the complete specification and maximum constraints.",
    "Privately construct a small direct specification and try to falsify the proposed algorithm.",
    "Check ordering, multiplicity, repeated values, boundaries, state changes, and complexity.",
    "Trace every published example. The execution harness compares output tokens exactly even when the problem prose grants mathematical tolerance.",
    "Match the required canonical representation, precision, rounding, ordering, and separators shown by the statement and examples.",
    "Do not print extra precision merely because it is available.",
    "Return only one complete raw Python 3 program without Markdown, fences, or explanation.",
))
_TOOLS_GUIDANCE = " ".join((
    "Work independently from the statement and do not assume any candidate implementation.",
    "Write a correctness-first oracle for small legal inputs using direct simulation or exhaustive search.",
    "Also write a generator accepting seed and size arguments, seeding Python random, and printing one varied legal input.",
    "Systematically include legal ties and equalities, repeated values, minimum counts, endpoints, mandatory final transitions, and choices where an equal local action changes a later opportunity.",
    "Vary these boundary families from the seed instead of emitting a fixed example.",
    "The oracle must not reuse the efficient algorithm requested by the statement.",
    "The execution harness compares output tokens exactly even when the prose permits numerical tolerance.",
    "Reproduce every published output token exactly and infer one canonical representation for unseen outputs from the statement and examples without inventing extra precision.",
    "Return exactly two fenced blocks named oracle and generator, with no other text.",
))
_CONFIRM_GUIDANCE = " ".join((
    "Independently derive a small-input reference program from the complete statement.",
    "Use direct simulation or exhaustive search rather than the intended efficient algorithm.",
    "Read the original input format and print the original output format.",
    "The execution harness compares output tokens exactly even when the prose permits numerical tolerance.",
    "Reproduce every published output token exactly and infer one canonical representation for unseen outputs from the statement and examples without inventing extra precision.",
    "Return one raw complete Python 3 program without Markdown or explanation.",
))
_REPAIR_GUIDANCE = " ".join((
    "Executed evidence disproved the program.",
    "Re-derive a general algorithm from the complete statement and constraints.",
    "Do not patch, fingerprint, or special-case the failing input.",
    "Return only one complete raw Python 3 program without Markdown, fences, or explanation.",
))
_FORMAT_REPAIR_GUIDANCE = " ".join((
    "Execution shows that the algorithm is numerically acceptable but its output representation violates the exact-token judge contract.",
    "Infer one general canonical precision, rounding, and formatting rule from the complete statement, examples, and independently confirmed expected tokens.",
    "Do not hardcode, fingerprint, or special-case the failing input or any observed numeric value.",
    "Return only one complete raw Python 3 program without Markdown, fences, or explanation.",
))
_PERFORMANCE_GUIDANCE = " ".join((
    "The program is correct on checked cases but execution showed that it is too slow at large scale.",
    "Replace it with an asymptotically faster general algorithm while preserving the input and output contract.",
    "Use buffered input and batched output where appropriate.",
    "Return only one complete raw Python 3 program without Markdown, fences, or explanation.",
))
_NUMERIC_GUIDANCE = " ".join((
    "Solve in the requested units and privately verify arithmetic, signs, rounding, and boundary assumptions.",
    "Put only the final numeric result on the last line.",
))
_INCONCLUSIVE = object()


def _is_code(text):
    value = str(text)
    return (
        "Write a complete Python 3 program" in value
        and "standard input" in value
        and "standard output" in value
    )


def _is_choice(text):
    body = "\n" + str(text)
    return all("\n" + letter + ")" in body for letter in "ABCD")


def _samples(prompt, maximum):
    text = str(prompt).replace("\r\n", "\n").replace("\r", "\n")
    marks = [(m.start(), m.end(), m.group(1), m.group(2)) for m in _SAMPLE.finditer(text)]
    blocks = {}
    for index, (_start, end, kind, number) in enumerate(marks):
        stop = marks[index + 1][0] if index + 1 < len(marks) else len(text)
        body = text[end:stop].strip("\n")
        if kind == "Output":
            body = body.split("\n\n", 1)[0]
        blocks.setdefault(number, {})[kind] = body.strip("\n")
    pairs = []
    for number in sorted(blocks, key=lambda value: int(value) if value.isdigit() else value):
        row = blocks[number]
        if row.get("Input", "").strip() and "Output" in row:
            pairs.append((row["Input"] + "\n", row["Output"]))
    return pairs[:maximum]


def _program(response):
    value = str(response or "")
    match = _FENCE.search(value)
    return (match.group(1) if match else value).strip()


def _tool_blocks(response):
    value = str(response or "")
    matches = _TOOLS.findall(value)
    if len(matches) != 2 or _TOOLS.sub("", value).strip():
        return {}
    names = [name.lower() for name, _code in matches]
    if sorted(names) != ["generator", "oracle"]:
        return {}
    blocks = {}
    for name, code in matches:
        encoded = code.encode("utf-8", "replace")
        if not code.strip() or len(encoded) > _MAX_TOOL_BYTES:
            return {}
        blocks[name.lower()] = code.strip()
    return blocks


def _limits():  # pragma: no cover - subprocess only
    resource.setrlimit(resource.RLIMIT_CPU, (_CHILD_CPU_S, _CHILD_CPU_S))
    resource.setrlimit(resource.RLIMIT_AS, (_CHILD_AS_BYTES, _CHILD_AS_BYTES))
    resource.setrlimit(resource.RLIMIT_NPROC, (_CHILD_NPROC, _CHILD_NPROC))
    resource.setrlimit(resource.RLIMIT_NOFILE, (_CHILD_NOFILE, _CHILD_NOFILE))
    resource.setrlimit(resource.RLIMIT_FSIZE, (_OUTPUT_LIMIT, _OUTPUT_LIMIT))
    resource.setrlimit(resource.RLIMIT_CORE, (0, 0))
    os.setsid()
    if os.geteuid() == 0:
        try:
            os.setgroups([])
        except PermissionError:
            pass
        os.setgid(65534)
        os.setuid(65534)


def _kill_group(process):
    try:
        os.killpg(os.getpgid(process.pid), signal.SIGKILL)
    except Exception:  # noqa: BLE001
        try:
            process.kill()
        except Exception:  # noqa: BLE001
            pass


def _safe_code(code):
    value = str(code)
    if not value.strip() or _UNSAFE.search(value):
        return False
    try:
        tree = ast.parse(value)
    except SyntaxError:
        return False
    for node in ast.walk(tree):
        if isinstance(node, ast.Import):
            if any(alias.name.split(".", 1)[0] not in _SAFE_IMPORTS for alias in node.names):
                return False
        elif isinstance(node, ast.ImportFrom):
            if node.level or not node.module:
                return False
            if node.module.split(".", 1)[0] not in _SAFE_IMPORTS:
                return False
        elif isinstance(node, ast.Name):
            if node.id in _BLOCKED_NAMES:
                return False
            if node.id.startswith("__") and node.id != "__name__":
                return False
        elif isinstance(node, ast.Attribute):
            if node.attr in _BLOCKED_ATTRIBUTES or node.attr.startswith("_"):
                return False
        elif isinstance(node, ast.Constant) and isinstance(node.value, str):
            lowered = node.value.lower()
            if any(marker in lowered for marker in _BLOCKED_TEXT):
                return False
    return True


def _execute(code, stdin_text, timeout, argv=()):
    if not _safe_code(code):
        return "rejected", ""
    path = None
    output = None
    process = None
    try:
        descriptor, path = tempfile.mkstemp(suffix=".py")
        with os.fdopen(descriptor, "w") as handle:
            handle.write(str(code))
        os.chmod(path, 0o444)
        output = tempfile.TemporaryFile()
        process = subprocess.Popen(
            [sys._base_executable, "-I", "-S", path, *[str(value) for value in argv]],
            stdin=subprocess.PIPE,
            stdout=output,
            stderr=subprocess.DEVNULL,
            preexec_fn=_limits,
            close_fds=True,
            cwd=tempfile.gettempdir(),
            env={"PATH": "/usr/bin:/bin", "PYTHONIOENCODING": "utf-8"},
        )
        try:
            process.communicate(str(stdin_text).encode("utf-8"), timeout=timeout)
        except subprocess.TimeoutExpired:
            _kill_group(process)
            process.communicate(timeout=2)
            return "timeout", ""
        if process.returncode != 0:
            return "exit", ""
        output.seek(0)
        raw = output.read(_OUTPUT_LIMIT + 1)
        if len(raw) > _OUTPUT_LIMIT:
            return "output_limit", ""
        return "ok", raw.decode("utf-8", "replace")
    except Exception:  # noqa: BLE001
        return "harness", ""
    finally:
        if process is not None and process.poll() is None:
            _kill_group(process)
        if output is not None:
            output.close()
        if path:
            try:
                os.unlink(path)
            except OSError:
                pass


def _bounded_timeout(until, maximum):
    if until is None:
        return maximum
    return max(0.05, min(maximum, until - time.monotonic()))


def _sample_failure(answer, cases, until=None):
    if not cases:
        return _INCONCLUSIVE
    code = _program(answer)
    if not _safe_code(code):
        return _INCONCLUSIVE
    for stdin_text, expected in cases:
        if until is not None and time.monotonic() >= until:
            return _INCONCLUSIVE
        status, observed = _execute(
            code, stdin_text, _bounded_timeout(until, _CASE_TIMEOUT_S),
        )
        if status in ("rejected", "harness"):
            return _INCONCLUSIVE
        if status != "ok" or not _same_output(observed, expected):
            shown = observed.strip() if status == "ok" else "<%s>" % status
            return stdin_text, shown or "<empty>", expected.strip()
    return None


def _same_output(left, right):
    return str(left).split() == str(right).split()


def _case_bank(
    oracle, generator, rounds, until=None, seed_base=67867967, exclude=(),
):
    bank = []
    seen = {
        hashlib.sha256(case.encode("utf-8", "replace")).digest()
        for case, _wanted in exclude
    }
    for index in range(rounds):
        if until is not None and time.monotonic() >= until:
            break
        status, case = _execute(
            generator, "", _bounded_timeout(until, _GENERATOR_TIMEOUT_S),
            argv=(seed_base + index, _SIZES[index % len(_SIZES)]),
        )
        encoded = case.encode("utf-8", "replace")
        if status != "ok" or not case.strip() or len(encoded) > _MAX_EVIDENCE_INPUT:
            continue
        digest = hashlib.sha256(encoded).digest()
        if digest in seen:
            continue
        if until is not None and time.monotonic() >= until:
            break
        oracle_status, wanted = _execute(
            oracle, case, _bounded_timeout(until, _CASE_TIMEOUT_S),
        )
        if oracle_status != "ok" or not wanted.strip():
            continue
        if len(wanted.encode("utf-8", "replace")) > _MAX_EVIDENCE_OUTPUT:
            continue
        seen.add(digest)
        bank.append((case, wanted))
    return bank


def _counterexample(answer, bank, until=None):
    code = _program(answer)
    if not _safe_code(code):
        return _INCONCLUSIVE
    for case, wanted in bank:
        if until is not None and time.monotonic() >= until:
            return _INCONCLUSIVE
        status, observed = _execute(
            code, case, _bounded_timeout(until, _CASE_TIMEOUT_S),
        )
        if status in ("rejected", "harness"):
            return _INCONCLUSIVE
        if status != "ok" or not _same_output(observed, wanted):
            shown = observed.strip() if status == "ok" else "<%s>" % status
            return case, shown or "<empty>", wanted.strip()
    return None


def _confirms(reference, cases, mismatch, until=None):
    if not reference or _sample_failure(reference, cases, until) is not None:
        return False
    if until is not None and time.monotonic() >= until:
        return False
    status, observed = _execute(
        _program(reference), mismatch[0], _bounded_timeout(until, _CASE_TIMEOUT_S),
    )
    return status == "ok" and _same_output(observed, mismatch[2])


def _performance_issue(answer, generator, until=None):
    if until is not None and time.monotonic() >= until:
        return _INCONCLUSIVE
    status, case = _execute(
        generator, "", _bounded_timeout(until, _PERF_GENERATOR_TIMEOUT_S),
        argv=(104729, _PERF_SIZE),
    )
    if status != "ok" or not case.strip():
        return None
    if until is not None and time.monotonic() >= until:
        return _INCONCLUSIVE
    started = time.monotonic()
    run_status, _output = _execute(
        _program(answer), case, _bounded_timeout(until, _PERF_TIMEOUT_S),
    )
    elapsed = time.monotonic() - started
    if until is not None and time.monotonic() >= until:
        return _INCONCLUSIVE
    if run_status == "ok" and elapsed <= _PERF_TARGET_S:
        return None
    return len(case.encode("utf-8", "replace")), elapsed, run_status


def _looks_large(prompt, threshold):
    text = str(prompt)
    for match in re.finditer(r"(?<![A-Za-z0-9_])(\d[\d,]*)(?![A-Za-z0-9_])", text):
        try:
            if int(match.group(1).replace(",", "")) >= threshold:
                return True
        except ValueError:
            continue
    for match in re.finditer(r"\b10\s*(?:\^|\*\*)\s*(\d{1,2})", text):
        if int(match.group(1)) >= len(str(threshold)) - 1:
            return True
    return False


def _stated_tolerance(prompt):
    text = str(prompt).lower()
    if "error" not in text and "tolerance" not in text:
        return None
    values = []
    for match in re.finditer(r"10\s*(?:\^|\*\*)?\s*\{?\s*[-−]\s*(\d{1,2})\s*\}?", text):
        exponent = int(match.group(1))
        if 1 <= exponent <= 18:
            values.append(Decimal(10) ** -exponent)
    for match in re.finditer(r"1(?:\.0+)?e-(\d{1,2})", text):
        exponent = int(match.group(1))
        if 1 <= exponent <= 18:
            values.append(Decimal(10) ** -exponent)
    return min(values) if values else None


def _same_differential_output(left, right, tolerance):
    left_tokens = str(left).split()
    right_tokens = str(right).split()
    if left_tokens == right_tokens:
        return True
    if tolerance is None or len(left_tokens) != len(right_tokens):
        return False
    for left_token, right_token in zip(left_tokens, right_tokens):
        if left_token == right_token:
            continue
        if not any(marker in left_token.lower() for marker in (".", "e")):
            return False
        if not any(marker in right_token.lower() for marker in (".", "e")):
            return False
        try:
            left_number = Decimal(left_token)
            right_number = Decimal(right_token)
        except InvalidOperation:
            return False
        if not left_number.is_finite() or not right_number.is_finite():
            return False
        scale = max(Decimal(1), abs(left_number), abs(right_number))
        if abs(left_number - right_number) > tolerance * scale:
            return False
    return True


def _differential_failure(answer, bank, tolerance, until=None):
    code = _program(answer)
    if not _safe_code(code):
        return _INCONCLUSIVE
    for case, wanted in bank:
        if until is not None and time.monotonic() >= until:
            return _INCONCLUSIVE
        status, observed = _execute(
            code, case, _bounded_timeout(until, _CASE_TIMEOUT_S),
        )
        if status in ("rejected", "harness"):
            return _INCONCLUSIVE
        if status != "ok" or not _same_differential_output(
            observed, wanted, tolerance,
        ):
            shown = observed.strip() if status == "ok" else "<%s>" % status
            return case, shown or "<empty>", wanted.strip()
    return None


def _differential_confirms(reference, cases, mismatch, tolerance, until=None):
    if not reference or _sample_failure(reference, cases, until) is not None:
        return False
    if until is not None and time.monotonic() >= until:
        return False
    status, observed = _execute(
        _program(reference), mismatch[0], _bounded_timeout(until, _CASE_TIMEOUT_S),
    )
    return status == "ok" and _same_differential_output(
        observed, mismatch[2], tolerance,
    )


def _load_policy(weights):
    try:
        policy = json.loads(bytes(weights).decode("utf-8"))
    except Exception as exc:
        raise ValueError("miner3-v9 weights are not valid JSON") from exc
    expected = {
        "code_call_cap": 5,
        "confirm_effort": "medium",
        "confirm_max_tokens": 12288,
        "confirm_model": _DIVERSE,
        "diverse_repair_effort": "medium",
        "diverse_repair_max_tokens": 12288,
        "diverse_repair_model": _DIVERSE,
        "floor_call_cap": 1,
        "floor_effort": "low",
        "format": _FORMAT,
        "future_task_reserve_s": 45,
        "holdout_rounds": 8,
        "local_guard_s": 55,
        "max_examples": 6,
        "min_holdout": 4,
        "min_valid_stress": 12,
        "performance_constraint_floor": 10000,
        "primary_effort": "low",
        "primary_max_tokens": 12288,
        "primary_model": _PRIMARY,
        "repair_effort": "medium",
        "repair_max_tokens": 16384,
        "run_call_cap": 12,
        "run_deadline_s": 600,
        "strategy_revision": 9,
        "stress_rounds": 48,
        "tools_effort": "low",
        "tools_fallback": _DIVERSE,
        "tools_max_tokens": 12288,
        "tools_model": _TOOLS_MODEL,
    }
    if not isinstance(policy, dict) or policy != expected:
        raise ValueError("miner3-v9 policy is malformed")
    return policy


def build_agent(weights):
    policy = _load_policy(weights)
    started = [None]
    served = [0]
    total_calls = [0]

    def agent(prompt, call_model):
        original = str(prompt)
        if started[0] is None:
            started[0] = time.monotonic()
        task_index = served[0]
        served[0] += 1
        calls = [0]
        code_task = _is_code(original)
        cap = policy["code_call_cap"] if code_task else policy["floor_call_cap"]
        future = max(0, _EXPECTED_TASKS - task_index - 1)
        task_deadline = (
            started[0] + policy["run_deadline_s"]
            - future * policy["future_task_reserve_s"]
        )
        verification_until = task_deadline - policy["local_guard_s"]

        def request(model, messages, effort, tokens, window):
            if calls[0] >= cap:
                raise RuntimeError("miner3-v9 per-task call limit exceeded")
            if total_calls[0] >= policy["run_call_cap"]:
                raise RuntimeError("miner3-v9 whole-run call limit exceeded")
            if time.monotonic() + window > task_deadline:
                raise TimeoutError("miner3-v9 shared deadline reserve reached")
            calls[0] += 1
            total_calls[0] += 1
            return call_model(
                model, messages,
                {"max_tokens": tokens, "reasoning": {"effort": effort}},
            )

        def one_user(content):
            return [{"role": "user", "content": content}]

        def confirm(mismatch, model, tolerance=None):
            try:
                reference = request(
                    model, one_user(original + "\n\n" + _CONFIRM_GUIDANCE),
                    policy["confirm_effort"], policy["confirm_max_tokens"], 40,
                )
            except Exception:
                return False
            if tolerance is None:
                return _confirms(reference, cases, mismatch, verification_until)
            return _differential_confirms(
                reference, cases, mismatch, tolerance, verification_until,
            )

        def repair(
            mismatch, model, effort, tokens, evidence_source,
            guidance=_REPAIR_GUIDANCE,
        ):
            repair_message = (
                guidance
                + "\nExecuted input:\n%s\nProgram output:\n%s"
                "\nTrusted expected output (%s):\n%s"
                % (mismatch[0], mismatch[1], evidence_source, mismatch[2])
            )
            try:
                return request(
                    model, one_user(original + "\n\n" + repair_message),
                    effort, tokens, 50,
                )
            except Exception:
                return ""

        if _is_choice(original):
            try:
                return request(
                    _PRIMARY, one_user(original), policy["floor_effort"],
                    policy["primary_max_tokens"], 25,
                )
            except Exception:
                return ""
        if not code_task:
            try:
                return request(
                    _PRIMARY, one_user(original + "\n\n" + _NUMERIC_GUIDANCE),
                    policy["floor_effort"], policy["primary_max_tokens"], 25,
                )
            except Exception:
                return ""

        cases = _samples(original, policy["max_examples"])
        tolerance = _stated_tolerance(original)
        try:
            candidate = request(
                _PRIMARY, one_user(original + "\n\n" + _DRAFT_GUIDANCE),
                policy["primary_effort"], policy["primary_max_tokens"], 40,
            )
        except Exception:
            return ""

        sample_bad = _sample_failure(candidate, cases, verification_until)
        if sample_bad is _INCONCLUSIVE:
            return candidate
        if sample_bad is not None:
            revised = repair(
                sample_bad, _PRIMARY, policy["repair_effort"],
                policy["repair_max_tokens"], "published sample",
            )
            return (
                revised
                if _sample_failure(revised, cases, verification_until) is None
                else candidate
            )

        def evidence_bank(model):
            if time.monotonic() + 5.0 >= verification_until:
                return "", "", []
            try:
                reply = request(
                    model, one_user(original + "\n\n" + _TOOLS_GUIDANCE),
                    policy["tools_effort"], policy["tools_max_tokens"], 40,
                )
            except Exception:
                return "", "", []
            blocks = _tool_blocks(reply)
            oracle = blocks.get("oracle", "")
            generator = blocks.get("generator", "")
            if not oracle or not generator:
                return "", "", []
            if _sample_failure(oracle, cases, verification_until) is not None:
                return "", "", []
            bank = _case_bank(
                oracle, generator, policy["stress_rounds"], verification_until,
            )
            if len(bank) < policy["min_valid_stress"]:
                return "", "", []
            return oracle, generator, bank

        oracle, generator, bank = evidence_bank(policy["tools_model"])
        fallback_used = not bank
        if fallback_used:
            oracle, generator, bank = evidence_bank(policy["tools_fallback"])
        if not bank:
            return candidate

        mismatch = _differential_failure(
            candidate, bank, tolerance, verification_until,
        )
        if mismatch is _INCONCLUSIVE:
            return candidate
        if mismatch is not None:
            confirm_model = _PRIMARY if fallback_used else policy["confirm_model"]
            if not confirm(mismatch, confirm_model, tolerance):
                return candidate
            repair_model = (
                policy["diverse_repair_model"] if fallback_used else _PRIMARY
            )
            repair_effort = (
                policy["diverse_repair_effort"]
                if fallback_used else policy["repair_effort"]
            )
            repaired = repair(
                mismatch, repair_model, repair_effort,
                (
                    policy["diverse_repair_max_tokens"]
                    if fallback_used else policy["repair_max_tokens"]
                ),
                "independent references",
            )
            if _sample_failure(repaired, cases, verification_until) is not None:
                return candidate
            if _differential_failure(
                repaired, bank, tolerance, verification_until,
            ) is not None:
                return candidate
            holdout = _case_bank(
                oracle, generator, policy["holdout_rounds"], verification_until,
                seed_base=982451653, exclude=bank,
            )
            if len(holdout) < policy["min_holdout"]:
                return candidate
            if _differential_failure(
                repaired, holdout, tolerance, verification_until,
            ) is not None:
                return candidate
            return repaired

        if tolerance is not None:
            format_mismatch = _counterexample(
                candidate, bank, verification_until,
            )
            if format_mismatch is _INCONCLUSIVE:
                return candidate
            if format_mismatch is not None:
                confirm_model = (
                    _PRIMARY if fallback_used else policy["confirm_model"]
                )
                if not confirm(format_mismatch, confirm_model):
                    return candidate
                repair_model = (
                    policy["diverse_repair_model"]
                    if fallback_used else _PRIMARY
                )
                repair_effort = (
                    policy["diverse_repair_effort"]
                    if fallback_used else policy["repair_effort"]
                )
                formatted = repair(
                    format_mismatch, repair_model, repair_effort,
                    (
                        policy["diverse_repair_max_tokens"]
                        if fallback_used else policy["repair_max_tokens"]
                    ),
                    "independently confirmed exact tokens",
                    _FORMAT_REPAIR_GUIDANCE,
                )
                if _sample_failure(
                    formatted, cases, verification_until,
                ) is not None:
                    return candidate
                if _counterexample(
                    formatted, bank, verification_until,
                ) is not None:
                    return candidate
                holdout = _case_bank(
                    oracle, generator, policy["holdout_rounds"],
                    verification_until, seed_base=982451653, exclude=bank,
                )
                if len(holdout) < policy["min_holdout"]:
                    return candidate
                if _counterexample(
                    formatted, holdout, verification_until,
                ) is not None:
                    return candidate
                return formatted

        if not _looks_large(original, policy["performance_constraint_floor"]):
            return candidate
        issue = _performance_issue(candidate, generator, verification_until)
        if issue in (None, _INCONCLUSIVE):
            return candidate
        bytes_count, elapsed, status = issue
        performance_message = (
            _PERFORMANCE_GUIDANCE
            + "\nMeasured input bytes: %d\nMeasured seconds: %.3f"
            "\nExecution status: %s" % (bytes_count, elapsed, status)
        )
        try:
            faster = request(
                _PRIMARY, one_user(original + "\n\n" + performance_message),
                policy["repair_effort"], policy["repair_max_tokens"], 50,
            )
        except Exception:
            return candidate
        if _sample_failure(faster, cases, verification_until) is not None:
            return candidate
        if _differential_failure(
            faster, bank, tolerance, verification_until,
        ) is not None:
            return candidate
        holdout = _case_bank(
            oracle, generator, policy["holdout_rounds"], verification_until,
            seed_base=961748927, exclude=bank,
        )
        if len(holdout) < policy["min_holdout"]:
            return candidate
        if _differential_failure(
            faster, holdout, tolerance, verification_until,
        ) is not None:
            return candidate
        return (
            faster
            if _performance_issue(faster, generator, verification_until) is None
            else candidate
        )

    return agent