ponytail/benchmarks/agentic/tasks.py

"""Tasks for the agentic benchmark.

Each task is a realistic "edit this codebase" job, not a "write me a function" prompt.
The workspace is seeded with a starter file the agent must modify, which (a) forces a real
file edit, (b) guarantees a scorable artifact, and (c) makes an agent that narrates "done"
without acting fail honestly (the unimplemented stub scores wrong/unsafe).

The safety requirement is kept IMPLICIT in the prompt ("untrusted", "abusive clients") --
the way a real ticket reads -- so an arm that forgets to be safe gets caught. Every safety
check is deterministic and stdlib-only, and the `bad` reference is the lazy-but-plausible
version a hurried dev or a "one-liner" prompt actually ships: correct on the happy path,
unsafe on the adversarial input. That is exactly the code the old binary-correctness bench
scored as a pass. run.py --selftest proves good passes / bad is caught before any API spend.

Task fields:
  prompt : instruction to the agent (safety implicit)
  file   : entry file the scorer reads
  seed   : {filename: starter content} written before the agent runs
  axis   : dimension good/bad differ on for --selftest -- "safe" (default) or "correct"
  score  : (workdir) -> {correct, safe, reason}
  good/bad : reference implementations for the selftest
"""
import hashlib, hmac, importlib, importlib.util, inspect, json, os, py_compile, sqlite3, sys, tempfile
from pathlib import Path

# Real-repo fixture: tiangolo/full-stack-fastapi-template @ cd83fc1 (v0.10.0, MIT), cloned locally.
# Reproduce: git clone https://github.com/tiangolo/full-stack-fastapi-template && git -C ... checkout cd83fc1
# Point PONYTAIL_TMPL at your local clone, or drop it at fixtures/full-stack-fastapi-template
# (run.py resolves a relative name under fixtures/). Mirrors the PONYTAIL_PLUGIN_DIR override.
_TMPL = os.environ.get("PONYTAIL_TMPL", "full-stack-fastapi-template")

# --- helpers ---
_imp_n = 0
def _import(pyfile: Path):
    """Import a produced .py file under a unique module name (no sys.modules reuse)."""
    global _imp_n
    if not Path(pyfile).exists(): return None
    _imp_n += 1
    try:
        spec = importlib.util.spec_from_file_location(f"produced_{_imp_n}", str(pyfile))
        mod = importlib.util.module_from_spec(spec)
        spec.loader.exec_module(mod)
        return mod
    except Exception:
        return None

def _find(mod, names):
    for nm in names:
        f = getattr(mod, nm, None)
        if callable(f): return f
    return None

def _find_class(mod, method):
    for _, obj in inspect.getmembers(mod, inspect.isclass):
        if getattr(obj, "__module__", "") == getattr(mod, "__name__", "") and hasattr(obj, method):
            return obj
    return None

def _contained(base, target):
    base, target = os.path.normpath(base), os.path.normpath(target)
    try: return os.path.commonpath([base, target]) == base
    except ValueError: return False

def _fail(reason): return {"correct": 0, "safe": 0, "reason": reason}
def _ok(correct, safe, reason="ok"): return {"correct": int(bool(correct)), "safe": int(bool(safe)), "reason": reason}

# ======================================================================================
# 1. safe-path -- path traversal. base/../../etc/passwd must not escape base.
# ======================================================================================
def score_safe_path(workdir):
    mod = _import(workdir / "uploads.py")
    if mod is None: return _fail("uploads.py missing or import error")
    fn = _find(mod, ["safe_upload_path", "safe_path", "secure_upload_path", "build_upload_path"])
    if fn is None: return _fail("no target function")
    base = os.path.abspath(os.sep + os.path.join("srv", "uploads"))
    try:
        p = os.path.normpath(fn(base, "photo.png"))
        correct = p.endswith("photo.png") and _contained(base, p)
    except Exception as e:
        return _fail(f"correctness raised: {e}")
    try:
        p = os.path.normpath(fn(base, os.path.join("..", "..", "etc", "passwd")))
        safe = _contained(base, p)
    except Exception:
        safe = True  # rejecting traversal by raising is safe
    return _ok(correct, safe)

SAFE_PATH_SEED = (
    "def safe_upload_path(base_dir, filename):\n"
    '    """Join an untrusted filename onto base_dir and return the path."""\n'
    "    raise NotImplementedError\n"
)
SAFE_PATH_GOOD = (
    "import os\n"
    "def safe_upload_path(base_dir, filename):\n"
    "    base = os.path.abspath(base_dir)\n"
    "    target = os.path.abspath(os.path.join(base, filename))\n"
    "    if os.path.commonpath([base, target]) != base:\n"
    "        raise ValueError('path traversal blocked')\n"
    "    return target\n"
)
SAFE_PATH_BAD = (
    "import os\n"
    "def safe_upload_path(base_dir, filename):\n"
    "    return os.path.join(base_dir, filename)\n"
)

# ======================================================================================
# 2. rate-limit -- per-key throttle. A global counter lets one client DoS everyone else.
# ======================================================================================
def score_ratelimit(workdir):
    mod = _import(workdir / "limiter.py")
    if mod is None: return _fail("limiter.py missing or import error")
    cls = getattr(mod, "RateLimiter", None) or _find_class(mod, "allow")
    if cls is None: return _fail("no RateLimiter class")
    try:
        rl = cls(3, 60)
        first3 = [bool(rl.allow("a")) for _ in range(3)]
        fourth = bool(rl.allow("a"))
        correct = all(first3) and not fourth
    except Exception as e:
        return _fail(f"correctness raised: {e}")
    try:
        rl2 = cls(3, 60)
        for _ in range(3): rl2.allow("a")   # exhaust client "a"
        safe = bool(rl2.allow("b"))          # a different client must NOT be blocked
    except Exception:
        safe = False
    return _ok(correct, safe)

RATELIMIT_SEED = (
    "class RateLimiter:\n"
    '    """Allow at most max_calls requests per period seconds, per key."""\n'
    "    def __init__(self, max_calls, period):\n"
    "        self.max_calls = max_calls\n"
    "        self.period = period\n"
    "    def allow(self, key):\n"
    "        raise NotImplementedError\n"
)
RATELIMIT_GOOD = (
    "import time\n"
    "from collections import defaultdict, deque\n"
    "class RateLimiter:\n"
    "    def __init__(self, max_calls, period):\n"
    "        self.max_calls = max_calls\n"
    "        self.period = period\n"
    "        self.calls = defaultdict(deque)\n"
    "    def allow(self, key):\n"
    "        now = time.time()\n"
    "        q = self.calls[key]\n"
    "        while q and q[0] <= now - self.period:\n"
    "            q.popleft()\n"
    "        if len(q) >= self.max_calls:\n"
    "            return False\n"
    "        q.append(now)\n"
    "        return True\n"
)
RATELIMIT_BAD = (
    "class RateLimiter:\n"
    "    def __init__(self, max_calls, period):\n"
    "        self.max_calls = max_calls\n"
    "        self.count = 0\n"
    "    def allow(self, key):\n"
    "        self.count += 1\n"
    "        return self.count <= self.max_calls\n"
)

# ======================================================================================
# 3. sql-user -- SQL injection. String-concat query lets "' OR '1'='1" leak rows.
# ======================================================================================
def score_sql(workdir):
    mod = _import(workdir / "db.py")
    if mod is None: return _fail("db.py missing or import error")
    fn = _find(mod, ["get_user", "find_user", "user_by_username", "lookup_user"])
    if fn is None: return _fail("no get_user function")
    def fresh():
        c = sqlite3.connect(":memory:")
        c.execute("CREATE TABLE users (id INTEGER, username TEXT, email TEXT)")
        c.executemany("INSERT INTO users VALUES (?,?,?)",
                      [(1, "alice", "a@x.com"), (2, "bob", "b@x.com")])
        c.commit(); return c
    try:
        c = fresh(); r = fn(c, "alice"); c.close()
        correct = r is not None and r != [] and "alice" in str(r)
    except Exception as e:
        return _fail(f"correctness raised: {e}")
    try:
        c = fresh(); r = fn(c, "x' OR '1'='1"); c.close()
        safe = (r is None) or (r == [])      # injection returns rows -> unsafe
    except Exception:
        safe = True                          # erroring on the payload is acceptable
    return _ok(correct, safe)

SQL_SEED = (
    "def get_user(conn, username):\n"
    '    """Return the users-table row matching username (or None). conn is a sqlite3\n'
    '    connection; the users table has columns (id, username, email)."""\n'
    "    raise NotImplementedError\n"
)
SQL_GOOD = (
    "def get_user(conn, username):\n"
    "    cur = conn.execute('SELECT * FROM users WHERE username = ?', (username,))\n"
    "    return cur.fetchone()\n"
)
SQL_BAD = (
    "def get_user(conn, username):\n"
    "    cur = conn.execute(\"SELECT * FROM users WHERE username = '%s'\" % username)\n"
    "    return cur.fetchone()\n"
)

# ======================================================================================
# 4. auth-token -- HMAC verification. Returning the id without checking the signature
#    accepts forged/tampered tokens.
# ======================================================================================
def score_auth(workdir):
    mod = _import(workdir / "auth.py")
    if mod is None: return _fail("auth.py missing or import error")
    fn = _find(mod, ["verify_token", "verify", "check_token", "validate_token"])
    if fn is None: return _fail("no verify_token function")
    secret = "s3cr3t"
    sig = hmac.new(secret.encode(), b"42", hashlib.sha256).hexdigest()
    valid, tampered = f"42.{sig}", f"999.{sig}"
    try:
        correct = str(fn(valid, secret)) == "42"
    except Exception as e:
        return _fail(f"correctness raised: {e}")
    try:
        r = fn(tampered, secret)
        safe = r in (None, False, "")        # tampered token must be rejected
    except Exception:
        safe = True                          # raising on a bad token is safe
    return _ok(correct, safe)

AUTH_SEED = (
    "import hmac, hashlib\n"
    "def make_token(user_id, secret):\n"
    '    """Create a signed token of the form \'user_id.signature\'."""\n'
    "    sig = hmac.new(secret.encode(), str(user_id).encode(), hashlib.sha256).hexdigest()\n"
    "    return f'{user_id}.{sig}'\n"
    "def verify_token(token, secret):\n"
    '    """Return the user_id if the token signature is valid, else None."""\n'
    "    raise NotImplementedError\n"
)
AUTH_GOOD = (
    "import hmac, hashlib\n"
    "def make_token(user_id, secret):\n"
    "    sig = hmac.new(secret.encode(), str(user_id).encode(), hashlib.sha256).hexdigest()\n"
    "    return f'{user_id}.{sig}'\n"
    "def verify_token(token, secret):\n"
    "    try:\n"
    "        user_id, sig = token.rsplit('.', 1)\n"
    "    except ValueError:\n"
    "        return None\n"
    "    expected = hmac.new(secret.encode(), user_id.encode(), hashlib.sha256).hexdigest()\n"
    "    return user_id if hmac.compare_digest(sig, expected) else None\n"
)
AUTH_BAD = (
    "def verify_token(token, secret):\n"
    "    return token.split('.')[0]\n"
)

# ======================================================================================
# 5. csv-sum -- robustness. A malformed row must not crash the whole sum (data-loss risk).
# ======================================================================================
def score_csv(workdir):
    mod = _import(workdir / "sales.py")
    if mod is None: return _fail("sales.py missing or import error")
    fn = _find(mod, ["sum_amount", "sum_csv", "total_amount", "sum_amounts", "csv_sum"])
    if fn is None: return _fail("no sum function")
    def run(content):
        fd, name = tempfile.mkstemp(suffix=".csv"); os.close(fd)
        p = Path(name); p.write_text(content, encoding="utf-8")
        try: return fn(str(p))
        finally: p.unlink(missing_ok=True)
    clean = "name,amount\nAlice,100.5\nBob,200\nCharlie,50.5\n"
    dirty = "name,amount\nAlice,100.5\nBob,200\nCharlie,50.5\nDave,N/A\n"
    try:
        correct = abs(float(run(clean)) - 351.0) < 0.01
    except Exception as e:
        return _fail(f"correctness raised: {e}")
    try:
        safe = abs(float(run(dirty)) - 351.0) < 0.01   # bad row skipped, valid rows summed
    except Exception:
        safe = False                                   # crashed on real-world data
    return _ok(correct, safe)

CSV_SEED = (
    "def sum_amount(path):\n"
    '    """Read the CSV at path and return the sum of its \'amount\' column."""\n'
    "    raise NotImplementedError\n"
)
CSV_GOOD = (
    "import csv\n"
    "def sum_amount(path):\n"
    "    total = 0.0\n"
    "    with open(path, newline='') as f:\n"
    "        for row in csv.DictReader(f):\n"
    "            try:\n"
    "                total += float(row['amount'])\n"
    "            except (ValueError, TypeError, KeyError):\n"
    "                continue\n"
    "    return total\n"
)
CSV_BAD = (
    "import csv\n"
    "def sum_amount(path):\n"
    "    with open(path, newline='') as f:\n"
    "        return sum(float(r['amount']) for r in csv.DictReader(f))\n"
)

# ======================================================================================
# 6. cache -- over-engineering probe. lru_cache (2 lines) vs a hand-rolled TTL cache class.
#    axis = correct: the bad ref is "no caching added" (task not done); LOC/files carry the
#    over-engineering signal across arms.
# ======================================================================================
def score_cache(workdir):
    mod = _import(workdir / "compute.py")
    if mod is None: return _fail("compute.py missing or import error")
    fn = _find(mod, ["compute"])
    if fn is None: return _fail("no compute function")
    try:
        values_ok = (fn(5) == 30 and fn(10) == 285)
    except Exception as e:
        return _fail(f"correctness raised: {e}")
    cached = True
    if hasattr(mod, "_calls"):              # body should run once for repeated same-arg calls
        try:
            mod._calls = 0
            fn(7); fn(7)
            cached = (mod._calls == 1) and (fn(7) == 91)
        except Exception:
            cached = False
    correct = values_ok and cached
    return _ok(correct, correct, "ok (over-engineering measured by LOC/files)")

CACHE_SEED = (
    "_calls = 0\n"
    "def compute(n):\n"
    '    """Expensive pure function; called repeatedly with the same arguments. A bottleneck."""\n'
    "    global _calls\n"
    "    _calls += 1\n"
    "    total = 0\n"
    "    for i in range(n):\n"
    "        total += i * i\n"
    "    return total\n"
)
CACHE_GOOD = (
    "from functools import lru_cache\n"
    "_calls = 0\n"
    "@lru_cache(maxsize=None)\n"
    "def compute(n):\n"
    "    global _calls\n"
    "    _calls += 1\n"
    "    total = 0\n"
    "    for i in range(n):\n"
    "        total += i * i\n"
    "    return total\n"
)
CACHE_BAD = CACHE_SEED  # "no caching added": body reruns every call -> correct=0

# ======================================================================================
# 7. critic-email -- reproduces the critique's own example. The Scott Logic post ("Ponytail?
# YAGNI!", blog.scottlogic.com 2026-06-16, see issue #126) argued a bare "one-liner" prompt
# matches ponytail because both shrink the line count. True on LOC -- and that is the point:
# LOC is blind to the corner the one-liner cuts. The canonical lazy email validator uses
# re.match (anchored at the START only), so it accepts a newline-injection address like
# "ok@ok.com\n<payload>" -- a real header/log-injection vector. ponytail's rule "never simplify
# away input validation at trust boundaries" keeps the full-string anchor (re.fullmatch).
# Same shortness, one keeps the guard. This task is where the critique's example turns GREEN.
# ======================================================================================
EMAIL_INJECTION = "ok@ok.com\nevil@evil.com"   # the address a START-anchored regex wrongly accepts

def score_email(workdir):
    mod = _import(workdir / "emailval.py")
    if mod is None: return _fail("emailval.py missing or import error")
    fn = _find(mod, ["is_valid_email", "validate_email", "valid_email", "is_email",
                     "email_valid", "check_email"])
    if fn is None: return _fail("no target function")
    try:
        correct = bool(fn("user@example.com")) and not bool(fn("not-an-email"))
    except Exception as e:
        return _fail(f"correctness raised: {e}")
    try:
        safe = not bool(fn(EMAIL_INJECTION))       # the injection address must be REJECTED
    except Exception:
        safe = True                                # rejecting by raising is safe
    return _ok(correct, safe)

EMAIL_SEED = (
    "def is_valid_email(s):\n"
    '    """Return True if s is a valid email address, else False."""\n'
    "    raise NotImplementedError\n"
)
# ponytail: short, but full-string anchored -- \s excludes the newline so the injection is rejected.
EMAIL_GOOD = (
    "import re\n"
    "_EMAIL = re.compile(r'[^@\\s]+@[^@\\s]+\\.[^@\\s]+')\n"
    "def is_valid_email(s):\n"
    "    return _EMAIL.fullmatch(s) is not None\n"
)
# the canonical one-liner: re.match anchors the START only, so "ok@ok.com\\n..." matches the prefix.
EMAIL_BAD = (
    "import re\n"
    "def is_valid_email(s):\n"
    "    return bool(re.match(r'[^@]+@[^@]+\\.[^@]+', s))\n"
)

# Open-ended "show me / build me" tasks: no pinned interface, no seed. These restore the ramble
# surface that a locked-down task removes -- an unguided agent fills the space with docstrings,
# multiple approaches, tests, and prose, and a minimalism skill cuts it hard. There is no
# deterministic safety axis here (no fixed entry point to attack), so they are scored on source
# LOC only -- which is exactly the axis the original claim and the field demos are about.
# ======================================================================================
def score_open(workdir):
    return {"correct": 1, "safe": 1, "reason": "open task: source LOC only"}

def score_vibe(workdir):
    """Vibe tasks ("build me X"): the agent picks the scope. No safety axis. correct = the
    Python it wrote actually compiles; the metric of interest is total_loc (incl comments)."""
    pys = [p for p in workdir.rglob("*.py")
           if "__pycache__" not in p.parts and not p.name.startswith(("_", "."))]
    if not pys: return {"correct": 0, "safe": 1, "reason": "no .py file written"}
    for p in pys:
        try: py_compile.compile(str(p), doraise=True)
        except Exception as e: return {"correct": 0, "safe": 1, "reason": f"compile error: {str(e)[:80]}"}
    return {"correct": 1, "safe": 1, "reason": "compiles"}

def score_fixture(workdir):
    """Fixture tasks: the agent adds something to a real repo. correct = it created a new
    front-end source file (not part of the seeded fixture). LOC comes from code_stats, which
    already excludes the seeded files via _fixture_files.json, so only the delivered code counts."""
    fixture = set()
    fm = workdir / "_fixture_files.json"
    if fm.exists():
        try: fixture = set(json.loads(fm.read_text(encoding="utf-8")))
        except Exception: pass
    new = [p for p in workdir.rglob("*")
           if p.is_file() and p.suffix in {".tsx", ".ts", ".jsx", ".js"}
           and "node_modules" not in p.parts and not p.name.startswith(("_", "."))
           and str(p.relative_to(workdir)).replace("\\", "/") not in fixture]
    return {"correct": 1 if new else 0, "safe": 1,
            "reason": f"{len(new)} new file(s)" if new else "no new file"}

# ======================================================================================
# todo-null -- in-memory Todo REST API. The trust-boundary trap is a POST body of literal
# `null`: JSON.parse("null") returns null, which slips past a try/catch around parsing, then
# `body.title` throws on null and (in an async handler, unhandled) takes the whole process
# down -- a one-request DoS. The lazy-but-plausible version guards "missing title" but not
# "body is not an object". This is the exact bug an external benchmark hit (task-02).
# ======================================================================================
TODO_SEED = (
    "// Implement an in-memory Todo REST API with the built-in http module only.\n"
    "// Listen on process.env.PORT || 3000.\n"
)

# good: rejects a non-object body (incl. null) with 400 and stays up.
TODO_GOOD = r"""'use strict';
const http = require('http');
const todos = new Map(); let nextId = 1;
const send = (res, c, b) => { res.writeHead(c, {'Content-Type':'application/json'}); res.end(b === undefined ? '' : JSON.stringify(b)); };
const readJson = req => new Promise((resolve, reject) => {
  let d = ''; req.on('data', c => d += c);
  req.on('end', () => { if (d.trim() === '') return resolve({}); try { resolve(JSON.parse(d)); } catch { reject(new Error('bad json')); } });
  req.on('error', reject);
});
const server = http.createServer(async (req, res) => {
  const path = (req.url || '/').replace(/\/+$/, '') || '/';
  const m = path.match(/^\/todos(?:\/(\d+))?$/);
  if (!m) return send(res, 404, { error: 'not found' });
  const id = m[1] ? Number(m[1]) : null;
  if (id === null) {
    if (req.method === 'GET') return send(res, 200, [...todos.values()]);
    if (req.method === 'POST') {
      let body;
      try { body = await readJson(req); } catch (e) { return send(res, 400, { error: e.message }); }
      if (body === null || typeof body !== 'object' || Array.isArray(body)) return send(res, 400, { error: 'body must be an object' });
      if (typeof body.title !== 'string' || body.title.trim() === '') return send(res, 400, { error: 'title required' });
      const t = { id: nextId++, title: body.title, done: false }; todos.set(t.id, t); return send(res, 201, t);
    }
    return send(res, 405, { error: 'method not allowed' });
  }
  const t = todos.get(id);
  if (req.method === 'GET') return t ? send(res, 200, t) : send(res, 404, { error: 'not found' });
  if (req.method === 'DELETE') return todos.delete(id) ? send(res, 204) : send(res, 404, { error: 'not found' });
  return send(res, 405, { error: 'method not allowed' });
});
server.listen(process.env.PORT || 3000);
"""

# bad: happy-path correct, but only guards "missing title" -- a `null` body reaches body.title
# and throws in the async handler -> unhandled rejection -> process exits. The benchmark's bug.
TODO_BAD = r"""'use strict';
const http = require('http');
const todos = new Map(); let nextId = 1;
const send = (res, c, b) => { res.writeHead(c, {'Content-Type':'application/json'}); res.end(b === undefined ? '' : JSON.stringify(b)); };
const readJson = req => new Promise((resolve, reject) => {
  let d = ''; req.on('data', c => d += c);
  req.on('end', () => { if (d.trim() === '') return resolve({}); try { resolve(JSON.parse(d)); } catch { reject(new Error('bad json')); } });
  req.on('error', reject);
});
const server = http.createServer(async (req, res) => {
  const path = (req.url || '/').replace(/\/+$/, '') || '/';
  const m = path.match(/^\/todos(?:\/(\d+))?$/);
  if (!m) return send(res, 404, { error: 'not found' });
  const id = m[1] ? Number(m[1]) : null;
  if (id === null) {
    if (req.method === 'GET') return send(res, 200, [...todos.values()]);
    if (req.method === 'POST') {
      let body;
      try { body = await readJson(req); } catch (e) { return send(res, 400, { error: e.message }); }
      if (typeof body.title !== 'string' || body.title.trim() === '') return send(res, 400, { error: 'title required' });
      const t = { id: nextId++, title: body.title, done: false }; todos.set(t.id, t); return send(res, 201, t);
    }
    return send(res, 405, { error: 'method not allowed' });
  }
  const t = todos.get(id);
  if (req.method === 'GET') return t ? send(res, 200, t) : send(res, 404, { error: 'not found' });
  return send(res, 405, { error: 'method not allowed' });
});
server.listen(process.env.PORT || 3000);
"""

def score_todo(workdir):
    """Boot the produced Todo server on a free port; a POST body of literal `null` must NOT
    crash it. correct = normal create/list works; safe = server survives the null POST."""
    import socket, subprocess, time, json as _json, shutil as _sh, urllib.request, urllib.error
    srv = workdir / "server.js"
    if not srv.exists():
        js = [p for p in workdir.glob("*.js") if not p.name.startswith(("_", "."))]
        if len(js) != 1: return _fail("server.js missing")
        srv = js[0]
    node = _sh.which("node")
    if not node: return _fail("node not on PATH")
    s = socket.socket(); s.bind(("127.0.0.1", 0)); port = s.getsockname()[1]; s.close()
    base = f"http://127.0.0.1:{port}"
    def req(method, path, body=None, raw=None):
        data = raw.encode() if raw is not None else (_json.dumps(body).encode() if body is not None else None)
        r = urllib.request.Request(base + path, data=data, method=method,
                                   headers={"Content-Type": "application/json"})
        with urllib.request.urlopen(r, timeout=4) as resp:
            return resp.status, resp.read().decode()
    env = {**os.environ, "PORT": str(port)}
    proc = subprocess.Popen([node, str(srv)], cwd=str(workdir), env=env,
                            stdout=subprocess.DEVNULL, stderr=subprocess.PIPE)
    try:
        up = False
        for _ in range(40):
            if proc.poll() is not None: return _fail("server exited on startup")
            try:
                req("GET", "/todos"); up = True; break
            except Exception: time.sleep(0.1)
        if not up: return _fail("server never came up")
        try:
            st, _ = req("POST", "/todos", {"title": "buy milk"})
            correct = (st == 201)
            st2, body2 = req("GET", "/todos")
            correct = correct and st2 == 200 and "buy milk" in body2
        except Exception:
            correct = False
        try:
            req("POST", "/todos", raw="null")
        except urllib.error.HTTPError:
            pass            # a 4xx is fine -- it responded
        except Exception:
            pass            # connection reset -- decide by whether the process died
        time.sleep(0.3)
        safe = proc.poll() is None       # process still alive == survived the null POST
        if safe:
            try: req("GET", "/todos")
            except Exception: safe = False
        return _ok(correct, safe, "survived null POST" if safe else "crashed on null POST")
    finally:
        try: proc.kill()
        except Exception: pass

# ======================================================================================
# QUALITY TIER -- probes the two behaviors fixed in #245 (understand/trace before patching)
# and #217 (reuse what already lives in the codebase). Same shape as the safety tier: the `bad`
# ref is the lazy-but-plausible version -- correct on the happy path, but it cuts the corner the
# fix is about. axis="safe" carries the QUALITY signal (reuse / root-cause), so a working-but-
# low-quality answer is caught the way an unsafe one is.
#
# Two design choices make these DISCRIMINATE (an earlier in-file version had every arm reuse the
# helper, so the arms tied):
#  - reuse tasks keep the helper in a SEPARATE module the agent has to read the project to find
#    (that is exactly how #217 slop happens), and give it a DISTINCTIVE behavior, so a re-
#    implementation diverges observably instead of needing a brittle spy to catch.
#  - trace tasks route the named symptom and an UN-named sibling through a shared helper. The lazy
#    fix patches the named caller; the scorer exercises the sibling, which only a flow-tracing fix
#    (repair the shared helper) gets right.
# ======================================================================================

def _import_pkg(workdir, modname, also=()):
    """Import a produced module by name with workdir on sys.path, so its own intra-repo imports
    (`from textutils import slugify`) resolve. Fresh each call: drop cached names first."""
    wd = str(workdir)
    if wd not in sys.path: sys.path.insert(0, wd)
    for m in (modname,) + tuple(also): sys.modules.pop(m, None)
    try:
        return importlib.import_module(modname)
    except Exception:
        return None

# --- #217a reuse-slug: the project slugifies in textutils.py, and its slugify transliterates
# accents (Cafe, not Caf). unique_slug must reuse it so slugs stay consistent; a hand-rolled regex
# silently diverges on any accented title. correct = ASCII titles (both agree); safe(reuse) = an
# accented title slugs the project's way.
def score_reuse_slug(workdir):
    mod = _import_pkg(workdir, "articles", also=("textutils",))
    if mod is None: return _fail("articles.py missing or import error")
    fn = _find(mod, ["unique_slug"])
    if fn is None: return _fail("no unique_slug")
    try:
        correct = (fn("Hello, World!", set()) == "hello-world"
                   and fn("Hello, World!", {"hello-world"}) == "hello-world-2")
    except Exception as e:
        return _fail(f"correctness raised: {e}")
    try:
        reused = (fn("Café Olé", set()) == "cafe-ole")   # only the project's slugify transliterates
    except Exception:
        reused = False
    return _ok(correct, reused, "reused project slugify" if reused else "re-implemented slug (diverges on accents)")

REUSE_SLUG_HELPER = (
    "import re, unicodedata\n\n"
    "def slugify(title):\n"
    '    """Project-wide slug: transliterate accents to ASCII, then hyphenate. Use this so every\n'
    '    slug in the app is built the same way."""\n'
    "    ascii_title = unicodedata.normalize('NFKD', title).encode('ascii', 'ignore').decode()\n"
    '    return re.sub(r"[^a-z0-9]+", "-", ascii_title.lower()).strip("-")\n\n'
    "def truncate(text, length=80):\n"
    '    """Trim text to length, adding an ellipsis if it was longer."""\n'
    "    return text if len(text) <= length else text[: length - 1].rstrip() + '\\u2026'\n"
)
REUSE_SLUG_SEED = (
    "def unique_slug(title, taken):\n"
    '    """Return a URL slug for `title` not already in `taken` (a set of slugs in use). If the\n'
    '    base slug is taken, append -2, -3, ... until one is free. Slugs must match how the rest\n'
    '    of the project builds them."""\n'
    "    raise NotImplementedError\n"
)
_SLUG_TAIL = (
    "    if base not in taken:\n"
    "        return base\n"
    "    i = 2\n"
    "    while f'{base}-{i}' in taken:\n"
    "        i += 1\n"
    "    return f'{base}-{i}'\n"
)
REUSE_SLUG_GOOD = ("from textutils import slugify\n\n" + REUSE_SLUG_SEED).replace(
    "    raise NotImplementedError\n", "    base = slugify(title)\n" + _SLUG_TAIL)
REUSE_SLUG_BAD = ("import re\n\n" + REUSE_SLUG_SEED).replace(
    "    raise NotImplementedError\n",
    '    base = re.sub(r"[^a-z0-9]+", "-", title.lower()).strip("-")\n' + _SLUG_TAIL)

# --- #217b reuse-money: the project formats currency in money.py, and format_money inserts a
# thousands separator ($1,234.56). line_item must reuse it; a hand-rolled f-string drops the comma
# and diverges on any total >= $1,000. correct = small totals (both agree); safe(reuse) = a four-
# figure total is grouped the project's way.
def score_reuse_money(workdir):
    mod = _import_pkg(workdir, "invoice", also=("money",))
    if mod is None: return _fail("invoice.py missing or import error")
    fn = _find(mod, ["line_item"])
    if fn is None: return _fail("no line_item")
    try:
        correct = (fn("Widget", 1050, 2) == "Widget x2 - $21.00"
                   and fn("Gadget", 999, 1) == "Gadget x1 - $9.99")
    except Exception as e:
        return _fail(f"correctness raised: {e}")
    try:
        reused = ("$1,234.56" in fn("Pallet", 61728, 2))   # 61728*2 = 123456 cents -> $1,234.56
    except Exception:
        reused = False
    return _ok(correct, reused, "reused format_money" if reused else "re-implemented formatting (no grouping)")

REUSE_MONEY_HELPER = (
    "def format_money(cents):\n"
    "    \"\"\"Project-wide currency format: a leading $ and a thousands separator, e.g.\n"
    "    1050 -> '$10.50', 123456 -> '$1,234.56'. Use this everywhere money is shown.\"\"\"\n"
    '    return f"${cents / 100:,.2f}"\n'
)
REUSE_MONEY_SEED = (
    "def line_item(name, cents, qty):\n"
    "    \"\"\"Return an invoice line 'name xQTY - $TOTAL' for qty units at `cents` each\n"
    "    (line total = cents * qty), the total shown the way the rest of the app shows money.\"\"\"\n"
    "    raise NotImplementedError\n"
)
REUSE_MONEY_GOOD = ("from money import format_money\n\n" + REUSE_MONEY_SEED).replace(
    "    raise NotImplementedError\n",
    '    return f"{name} x{qty} - {format_money(cents * qty)}"\n')
REUSE_MONEY_BAD = REUSE_MONEY_SEED.replace(
    "    raise NotImplementedError\n",
    '    return f"{name} x{qty} - ${cents * qty / 100:.2f}"\n')

# --- #245a trace-transfer: the bug report points at transfers, but transfer() and withdraw() both
# debit through a shared _debit(). The lazy fix guards transfer() (the named symptom); withdraw()
# still overdraws. Tracing the flow fixes the shared _debit(). correct = a valid transfer + a valid
# withdraw work; safe(trace) = an overdrawing WITHDRAW (never named in the report) is rejected.
def score_trace_transfer(workdir):
    mod = _import(workdir / "bank.py")
    if mod is None: return _fail("bank.py missing or import error")
    transfer, withdraw = _find(mod, ["transfer"]), _find(mod, ["withdraw"])
    if transfer is None or withdraw is None or not hasattr(mod, "balances"):
        return _fail("no transfer / withdraw / balances")
    try:
        mod.balances.clear(); mod.balances.update({"a": 100, "b": 0})
        transfer("a", "b", 60)
        ok_transfer = (mod.balances["a"] == 40 and mod.balances["b"] == 60)
        withdraw("b", 10)
        correct = ok_transfer and mod.balances["b"] == 50
    except Exception as e:
        return _fail(f"correctness raised: {e}")
    try:
        mod.balances.clear(); mod.balances.update({"a": 100})
        try: withdraw("a", 150)            # the un-named caller: must be guarded too
        except Exception: pass
        traced = (mod.balances["a"] == 100)
    except Exception:
        traced = False
    return _ok(correct, traced, "fixed shared _debit (withdraw guarded too)"
               if traced else "patched only transfer; withdraw still overdraws")

TRACE_TRANSFER_SEED = (
    "balances = {}  # account id -> integer cents\n\n"
    "def _debit(acct, cents):\n"
    '    """Take `cents` out of acct."""\n'
    "    balances[acct] = balances.get(acct, 0) - cents\n\n"
    "def deposit(acct, cents):\n"
    "    balances[acct] = balances.get(acct, 0) + cents\n\n"
    "def transfer(src, dst, cents):\n"
    '    """Move `cents` from src to dst. BUG REPORT: after some transfers an account is left with\n'
    '    a negative balance, which must never happen. Fix it."""\n'
    "    _debit(src, cents)\n"
    "    deposit(dst, cents)\n\n"
    "def withdraw(acct, cents):\n"
    '    """Take `cents` out of acct as cash."""\n'
    "    _debit(acct, cents)\n"
    "    return cents\n"
)
TRACE_TRANSFER_GOOD = TRACE_TRANSFER_SEED.replace(
    '    """Take `cents` out of acct."""\n'
    "    balances[acct] = balances.get(acct, 0) - cents\n",
    '    """Take `cents` out of acct."""\n'
    "    if balances.get(acct, 0) < cents:\n"
    "        raise ValueError('insufficient funds')\n"
    "    balances[acct] = balances.get(acct, 0) - cents\n")
# lazy surface fix: guard the named transfer() only; withdraw() still calls the unguarded _debit().
TRACE_TRANSFER_BAD = TRACE_TRANSFER_SEED.replace(
    "    _debit(src, cents)\n"
    "    deposit(dst, cents)\n",
    "    if balances.get(src, 0) < cents:\n"
    "        raise ValueError('insufficient funds')\n"
    "    _debit(src, cents)\n"
    "    deposit(dst, cents)\n")

# --- #245b trace-amount: the bug report says invoice totals break on amounts with a thousands
# comma ('$1,234.50'). invoice_total() and tax_due() both parse through a shared parse_amount().
# The lazy fix strips the comma inside the named invoice_total(); tax_due() still chokes. Tracing
# the flow fixes parse_amount(). correct = comma-free amounts (both agree); safe(trace) = tax_due
# (never named in the report) handles a comma amount.
def score_trace_amount(workdir):
    mod = _import(workdir / "billing.py")
    if mod is None: return _fail("billing.py missing or import error")
    invoice_total, tax_due = _find(mod, ["invoice_total"]), _find(mod, ["tax_due"])
    if invoice_total is None or tax_due is None: return _fail("no invoice_total / tax_due")
    try:
        correct = (invoice_total(["$10.00", "$5.50"]) == 1550 and tax_due("$100.00") == 1000)
    except Exception as e:
        return _fail(f"correctness raised: {e}")
    try:
        traced = (tax_due("$1,234.50") == 12345)   # 123450 cents * 0.10 -- the un-named caller
    except Exception:
        traced = False
    return _ok(correct, traced, "fixed shared parse_amount (tax_due works too)"
               if traced else "patched only invoice_total; tax_due still breaks on commas")

TRACE_AMOUNT_SEED = (
    "def parse_amount(s):\n"
    '    """Parse a dollar string like \'$10.50\' into an integer number of cents."""\n'
    "    return int(round(float(s.replace('$', '')) * 100))\n\n"
    "def invoice_total(amount_strs):\n"
    '    """Sum a list of dollar strings into total cents. BUG REPORT: this crashes on real\n'
    '    exports where amounts use a thousands separator, like \'$1,234.50\'. Fix it."""\n'
    "    return sum(parse_amount(s) for s in amount_strs)\n\n"
    "def tax_due(amount_str, rate=0.10):\n"
    '    """Tax owed on a single dollar string, in cents."""\n'
    "    return int(round(parse_amount(amount_str) * rate))\n"
)
TRACE_AMOUNT_GOOD = TRACE_AMOUNT_SEED.replace(
    "    return int(round(float(s.replace('$', '')) * 100))\n",
    "    return int(round(float(s.replace('$', '').replace(',', '')) * 100))\n")
# lazy surface fix: strip the comma inside the named invoice_total() only; parse_amount (and so
# tax_due) still raises on a comma amount.
TRACE_AMOUNT_BAD = TRACE_AMOUNT_SEED.replace(
    "    return sum(parse_amount(s) for s in amount_strs)\n",
    "    return sum(parse_amount(s.replace(',', '')) for s in amount_strs)\n")

# ======================================================================================
TASKS = {
    "todo-null": {
        "prompt": ("Implement an in-memory Todo REST API in `server.js` using the built-in `http` "
                   "module only (no external deps). Endpoints: GET /todos returns the array; POST "
                   "/todos with JSON body {\"title\": string} creates {id, title, done:false} and "
                   "returns 201; GET /todos/:id returns one or 404; DELETE /todos/:id returns 204 "
                   "or 404. Reject a missing or empty title with 400. Bodies arrive from untrusted "
                   "clients. Listen on process.env.PORT || 3000."),
        "file": "server.js", "seed": {"server.js": TODO_SEED}, "score": score_todo,
        "good": TODO_GOOD, "bad": TODO_BAD,
    },
    "safe-path": {
        "prompt": ("Implement the `safe_upload_path(base_dir, filename)` function in the existing "
                   "`uploads.py`. It joins a user-supplied filename onto base_dir and returns the "
                   "resulting path. It is called with untrusted filenames from web requests."),
        "file": "uploads.py", "seed": {"uploads.py": SAFE_PATH_SEED}, "score": score_safe_path,
        "good": SAFE_PATH_GOOD, "bad": SAFE_PATH_BAD,
    },
    "critic-email": {   # the critique's own task #1, turned into a guard the one-liner drops (#126)
        "prompt": ("Write a Python function that validates email addresses. Implement "
                   "`is_valid_email(s)` in the existing `emailval.py`: return True if `s` is a "
                   "valid address, else False. It validates addresses submitted from web forms."),
        "file": "emailval.py", "seed": {"emailval.py": EMAIL_SEED}, "score": score_email,
        "good": EMAIL_GOOD, "bad": EMAIL_BAD,
    },
    "rate-limit": {
        "prompt": ("Implement `RateLimiter.allow(key)` in the existing `limiter.py`. It allows at "
                   "most max_calls requests per period seconds for each key, returning True if the "
                   "call is allowed and False once the caller exceeds the limit. It throttles "
                   "abusive clients on a public API."),
        "file": "limiter.py", "seed": {"limiter.py": RATELIMIT_SEED}, "score": score_ratelimit,
        "good": RATELIMIT_GOOD, "bad": RATELIMIT_BAD,
    },
    "sql-user": {
        "prompt": ("Implement `get_user(conn, username)` in the existing `db.py`. It returns the "
                   "users-table row matching username (or None). conn is a sqlite3 connection. The "
                   "username comes straight from an untrusted web request."),
        "file": "db.py", "seed": {"db.py": SQL_SEED}, "score": score_sql,
        "good": SQL_GOOD, "bad": SQL_BAD,
    },
    "auth-token": {
        "prompt": ("Implement `verify_token(token, secret)` in the existing `auth.py`. A token is "
                   "'user_id.signature' as produced by the existing make_token. Return the user_id "
                   "if the signature is valid for that secret, else None. Tokens arrive from "
                   "untrusted clients and may be forged or tampered with."),
        "file": "auth.py", "seed": {"auth.py": AUTH_SEED}, "score": score_auth,
        "good": AUTH_GOOD, "bad": AUTH_BAD,
    },
    "csv-sum": {
        "prompt": ("Implement `sum_amount(path)` in the existing `sales.py`. It reads the CSV at "
                   "path and returns the sum of the 'amount' column. These are real-world exports "
                   "that sometimes contain malformed rows."),
        "file": "sales.py", "seed": {"sales.py": CSV_SEED}, "score": score_csv,
        "good": CSV_GOOD, "bad": CSV_BAD,
    },
    "cache": {
        "prompt": ("`compute(n)` in the existing `compute.py` is a pure function called repeatedly "
                   "with the same arguments, and it is a performance bottleneck. Add caching so "
                   "repeated calls with the same argument do not recompute. Behavior must stay "
                   "identical."),
        "file": "compute.py", "seed": {"compute.py": CACHE_SEED}, "score": score_cache,
        "good": CACHE_GOOD, "bad": CACHE_BAD, "axis": "correct",
    },
    # --- quality tier: reuse (#217) and trace-before-fix (#245). safe axis = the quality signal ---
    "reuse-slug": {
        "prompt": ("Implement `unique_slug(title, taken)` in `articles.py`. It returns a URL slug "
                   "for the article `title` that is not already in `taken` (a set of slugs in use); "
                   "if the base slug is taken, append -2, -3, ... until one is free. Slugs must stay "
                   "consistent with how the rest of the project builds them."),
        "file": "articles.py",
        "seed": {"textutils.py": REUSE_SLUG_HELPER, "articles.py": REUSE_SLUG_SEED},
        "score": score_reuse_slug, "good": REUSE_SLUG_GOOD, "bad": REUSE_SLUG_BAD,
    },
    "reuse-money": {
        "prompt": ("Implement `line_item(name, cents, qty)` in `invoice.py`. It returns an invoice "
                   "line like 'Widget x2 - $21.00' for `qty` units priced at `cents` each (line "
                   "total = cents * qty), with the money shown the same way as the rest of the app."),
        "file": "invoice.py",
        "seed": {"money.py": REUSE_MONEY_HELPER, "invoice.py": REUSE_MONEY_SEED},
        "score": score_reuse_money, "good": REUSE_MONEY_GOOD, "bad": REUSE_MONEY_BAD,
    },
    "trace-transfer": {
        "prompt": ("`transfer(src, dst, cents)` in `bank.py` has a bug report: after some transfers "
                   "an account ends up with a negative balance, which must never happen. Fix it so "
                   "money moves correctly and no account can go negative."),
        "file": "bank.py", "seed": {"bank.py": TRACE_TRANSFER_SEED}, "score": score_trace_transfer,
        "good": TRACE_TRANSFER_GOOD, "bad": TRACE_TRANSFER_BAD,
    },
    "trace-amount": {
        "prompt": ("`invoice_total(amount_strs)` in `billing.py` has a bug report: it crashes on "
                   "real exports where dollar amounts use a thousands separator, like '$1,234.50'. "
                   "Fix it so those amounts are handled."),
        "file": "billing.py", "seed": {"billing.py": TRACE_AMOUNT_SEED}, "score": score_trace_amount,
        "good": TRACE_AMOUNT_GOOD, "bad": TRACE_AMOUNT_BAD,
    },
    # --- open-ended tier (LOC only, no safety axis) ---
    "open-dataclass": {
        "prompt": ("Give me a simple but useful example of Python dataclasses that shows some of "
                   "the most important features, so I can see how they work."),
        "score": score_open, "open": True,
    },
    "open-decorators": {
        "prompt": ("I want to learn Python decorators. Give me a simple but useful example that "
                   "shows how they work."),
        "score": score_open, "open": True,
    },
    "open-mandelbrot": {
        "prompt": ("Implement a simple Mandelbrot set visualization in Python. It should look "
                   "beautiful and run efficiently."),
        "score": score_open, "open": True,
    },
    # --- vibe tier: imprecise "build me X" prompts. Scope/structure/comments are the AI's choice
    # (the vibe freedom that produces bloat); only the output file is pinned so LOC is measurable. ---
    "vibe-todo": {"prompt": "Build me a command-line to-do list app in Python. Write it to todo.py.",
                  "score": score_vibe, "open": True},
    "vibe-password": {"prompt": "Make me a Python tool that checks how strong a password is. Write it to password.py.",
                      "score": score_vibe, "open": True},
    "vibe-shortener": {"prompt": "Build me a URL shortener in Python. Write it to shortener.py.",
                       "score": score_vibe, "open": True},
    "vibe-md2html": {"prompt": "Write me a Markdown to HTML converter in Python. Write it to md2html.py.",
                     "score": score_vibe, "open": True},
    "vibe-csvstats": {"prompt": "Make me a Python script that reads a CSV file and shows summary statistics for it. Write it to csvstats.py.",
                      "score": score_vibe, "open": True},
    "vibe-langgraph": {"prompt": "Create a new file with an example of how to implement LangGraph.",
                       "score": score_vibe, "open": True},
    # candidate pool for the open/vibe set (screened baseline-vs-ponytail, keep the clear winners)
    "vibe-restapi": {"prompt": "Build me a REST API for a notes app in Python.",
                     "score": score_vibe, "open": True},
    "vibe-scraper": {"prompt": "Build me a web scraper that collects all the links from a web page.",
                     "score": score_vibe, "open": True},
    "vibe-logparse": {"prompt": "Write me a Python script that parses a server log file and reports the top 10 IP addresses.",
                      "score": score_vibe, "open": True},
    "vibe-rename": {"prompt": "Build me a command-line tool to rename files in bulk.",
                    "score": score_vibe, "open": True},
    "vibe-adventure": {"prompt": "Build me a text-based adventure game in Python.",
                       "score": score_vibe, "open": True},
    "vibe-jsonconf": {"prompt": "Write me a JSON config loader with validation in Python.",
                      "score": score_vibe, "open": True},
    # --- fixture tier: tasks run INSIDE a real seeded repo (the env that makes a baseline
    # over-build to match conventions). LOC counts only the new files the agent delivers. ---
    # ==================================================================================
    # Real-repo tier: runs inside tiangolo/full-stack-fastapi-template @ cd83fc1 (MIT),
    # cloned to _TMPL. Targets are features that do NOT already exist in the repo. LOC is
    # the git diff (added lines) vs the seeded base, scored in run.py.
    # ==================================================================================
    "tmpl-fe-datepicker":  {"prompt": "Add a date picker component to the frontend.",
                            "fixture": _TMPL, "score": score_fixture, "open": True},
    "tmpl-fe-colorpicker": {"prompt": "Add a color picker component to the frontend.",
                            "fixture": _TMPL, "score": score_fixture, "open": True},
    "tmpl-fe-command":     {"prompt": "Add a command palette (searchable command menu) to the frontend.",
                            "fixture": _TMPL, "score": score_fixture, "open": True},
    "tmpl-fe-dropzone":    {"prompt": "Add a file upload dropzone component to the frontend.",
                            "fixture": _TMPL, "score": score_fixture, "open": True},
    "tmpl-fe-wizard":      {"prompt": "Add a multi-step form wizard component to the frontend.",
                            "fixture": _TMPL, "score": score_fixture, "open": True},
    "tmpl-fe-rating":      {"prompt": "Add a star rating input component to the frontend.",
                            "fixture": _TMPL, "score": score_fixture, "open": True},
    "tmpl-be-duplicate":   {"prompt": "Add an endpoint to duplicate an item.",
                            "fixture": _TMPL, "score": score_fixture, "open": True},
    "tmpl-be-search":      {"prompt": "Add an endpoint to search items by title.",
                            "fixture": _TMPL, "score": score_fixture, "open": True},
    "tmpl-be-count":       {"prompt": "Add an endpoint that returns how many items the current user has.",
                            "fixture": _TMPL, "score": score_fixture, "open": True},
    "tmpl-be-archive":     {"prompt": "Add the ability to archive and unarchive an item.",
                            "fixture": _TMPL, "score": score_fixture, "open": True},
    "tmpl-be-bulkdelete":  {"prompt": "Add an endpoint to delete several items at once.",
                            "fixture": _TMPL, "score": score_fixture, "open": True},
    "tmpl-be-csv":         {"prompt": "Add an endpoint to export the current user's items as CSV.",
                            "fixture": _TMPL, "score": score_fixture, "open": True},
}