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Python

#!/usr/bin/env python3
"""checklint -- lint the CHECK line of a Wizard Troupe standup entry.
The troupe's lane contract is one line:
CHECK: <single bare shell command>
whose own exit code IS the verdict: 0 = correct, nonzero = wrong. Two defects
keep recurring in this loop, and both are statically detectable before any
command runs:
* the CHECK line carries a fallback arm (`cmd || true`, `cmd; exit 0`,
`cmd || echo ...`) or is a constant-success builtin (`true`, `exit 0`).
The exit code is then 0 whatever the command did: a gate that cannot fail.
* the CHECK line is not one bare command (`a && b`, `a | b`, a redirect, a
line continuation), so the harness cannot run it as written and the
multi-command line resolves to whichever arm last ran.
checklint reads an entry, extracts the top-level CHECK line, and reports one
finding per defect. `--run` adds the only non-static leg: it executes the
extracted command with a timeout and folds the command's REAL exit code into
the verdict.
Exit code IS the verdict:
0 the CHECK line is clean (and, with --run, the command exited 0)
1 a graded fault (one or more findings)
2 COULD NOT GRADE (entry unreadable, command could not be executed,
timed out) -- every 2 names its cause, and a 2 is never a fault
Usage:
checklint entry.md
checklint --run entry.md
checklint --scan . # every file under DIR carrying a CHECK line
checklint --json entry.md
`--scan` is a gate over a corpus: it exits 1 when any scanned file has
findings, 0 when every CHECK line in the tree is clean, 2 when the tree could
not be read. It skips .git, __pycache__ and files whose first 8 KiB contain a
NUL byte.
Deliberately NOT checked: whether the command's assertions are strong enough.
A CHECK line can be one bare command and still assert nothing (`test -f f`); a
static linter cannot see that. It is documented here because a reader who
assumes checklint grades the quality of the gate would be wrong.
"""
from __future__ import annotations
import argparse
import json
import os
import re
import subprocess
import sys
from dataclasses import dataclass, asdict
from pathlib import Path
PROG = "checklint"
DEFAULT_TIMEOUT = 300.0
# Shell control operators and substitution that turn a CHECK line into more
# than one command, into a substitution, or into a redirected command. The
# contract is one bare command whose exit code is its own, so all of these are
# faults -- including `2>/dev/null`, which is still a redirect.
METACHARS = "`$<>&|;(){}"
# A fallback arm forces the exit code to 0 (or to the arm's own code) whatever
# the command did. Reported by name, because "it contains |" does not tell a
# reader why the gate cannot fail.
FALLBACK_PATTERNS: tuple[tuple[str, re.Pattern[str]], ...] = (
("cmd || true", re.compile(r"\|\|\s*(?:true|:)\s*$")),
("cmd || exit 0", re.compile(r"\|\|\s*exit\s+0\s*$")),
("cmd || echo/printf ...", re.compile(r"\|\|\s*(?:echo|printf)\b")),
("cmd ; exit 0", re.compile(r";\s*exit\s+0\s*$")),
("cmd ; true", re.compile(r";\s*(?:true|:)\s*$")),
("cmd ; echo/printf ...", re.compile(r";\s*(?:echo|printf)\b")),
)
# Commands that always succeed. Exact match on the stripped command.
TAUTOLOGIES = frozenset(
{
"true",
":",
"exit 0",
"echo",
"echo ok",
"echo pass",
"echo PASS",
"echo 0",
"printf ok",
"test 1 -eq 1",
"test 1 = 1",
"test -f /dev/null",
"test -e /",
}
)
FENCE_RE = re.compile(r"^\s*(?:```|~~~)")
CHECK_RE = re.compile(r"^\s*CHECK\s*:\s*(.*)$")
SKIP_DIRS = {".git", "__pycache__", ".pytest_cache", ".ruff_cache"}
@dataclass(frozen=True)
class Finding:
"""One defect. kind is 'error' (a graded fault) or 'cng' (could not grade)."""
code: str
line: int | None
message: str
kind: str = "error"
def as_dict(self) -> dict:
return asdict(self)
def iter_prose_lines(text: str):
"""Yield (lineno, raw_line) for lines outside fenced code blocks.
A CHECK line inside a ``` fence is a replay transcript, not the contract.
"""
in_fence = False
for lineno, raw in enumerate(text.split("\n"), start=1):
if FENCE_RE.match(raw):
in_fence = not in_fence
continue
if not in_fence:
yield lineno, raw
def find_check_lines(text: str) -> list[tuple[int, str]]:
"""Top-level CHECK lines as (lineno, command-stripped) pairs."""
hits = []
for lineno, raw in iter_prose_lines(text):
m = CHECK_RE.match(raw)
if m:
hits.append((lineno, m.group(1).strip()))
return hits
def lint_command(cmd: str, lineno: int) -> list[Finding]:
"""Static findings for one extracted command."""
out: list[Finding] = []
if cmd.endswith("\\"):
out.append(
Finding("METACHAR", lineno, f"CHECK line ends a line continuation: {cmd!r}")
)
return out
for label, rx in FALLBACK_PATTERNS:
if rx.search(cmd):
out.append(
Finding(
"FALLBACK_ARM",
lineno,
f"CHECK line carries a fallback arm ({label}): {cmd!r} -- "
"the exit code is forced, so the gate cannot fail",
)
)
break
bad = "".join(sorted({c for c in cmd if c in METACHARS}))
if bad:
out.append(
Finding(
"METACHAR",
lineno,
f"CHECK line contains shell metacharacters {bad!r}: {cmd!r} -- "
"the contract is ONE bare command with no shell metacharacters",
)
)
if cmd in TAUTOLOGIES:
out.append(
Finding(
"TAUTOLOGY",
lineno,
f"CHECK line is the constant-success command {cmd!r} -- "
"the gate cannot fail",
)
)
return out
def lint_text(text: str) -> list[Finding]:
"""Every finding for one entry's text."""
hits = find_check_lines(text)
if not hits:
return [
Finding("MISSING", None, "no top-level 'CHECK: <command>' line in the entry")
]
if len(hits) > 1:
where = ", ".join(str(n) for n, _ in hits)
return [
Finding(
"MULTIPLE",
hits[1][0],
f"{len(hits)} top-level CHECK lines (lines {where}); the contract is exactly one",
)
]
lineno, cmd = hits[0]
if not cmd:
return [Finding("EMPTY", lineno, "CHECK line carries no command")]
return lint_command(cmd, lineno)
def run_check_command(cmd: str, timeout: float) -> tuple[int | None, str]:
"""Execute the extracted command. Returns (exit_code, detail)."""
try:
proc = subprocess.run(
cmd,
shell=True,
capture_output=True,
text=True,
timeout=timeout,
)
except subprocess.TimeoutExpired:
return None, f"timed out after {timeout:g}s"
except OSError as exc:
return None, f"could not execute: {exc}"
tail = (proc.stderr or proc.stdout or "").strip().splitlines()
detail = f"exit {proc.returncode}"
if tail:
detail += f" | last output line: {tail[-1][:160]}"
return proc.returncode, detail
def grade(
text: str, *, run: bool = False, timeout: float = DEFAULT_TIMEOUT
) -> tuple[list[Finding], int]:
"""Lint, and optionally execute. Returns (findings, verdict).
verdict: 0 clean, 1 fault, 2 could-not-grade.
"""
findings = lint_text(text)
blocking = {"MISSING", "EMPTY", "MULTIPLE", "FALLBACK_ARM", "METACHAR", "TAUTOLOGY"}
if run and not any(f.code in blocking for f in findings):
cmd = find_check_lines(text)[0][1]
code, detail = run_check_command(cmd, timeout)
if code is None:
if detail.startswith("timed out"):
findings.append(Finding("TIMEOUT", find_check_lines(text)[0][0], detail, "cng"))
else:
findings.append(Finding("UNREADABLE", find_check_lines(text)[0][0], detail, "cng"))
elif code != 0:
findings.append(
Finding(
"RUN_FAILURE",
find_check_lines(text)[0][0],
f"the CHECK command exited {code} ({detail})",
)
)
if any(f.kind == "cng" for f in findings):
return findings, 2
if findings:
return findings, 1
return findings, 0
def read_text(path: Path) -> str:
"""Read a file as text; binary content is reported, never guessed at."""
raw = path.read_bytes()
if b"\0" in raw[:8192]:
raise ValueError(f"{path}: binary (NUL byte in first 8 KiB)")
return raw.decode("utf-8", errors="replace")
def report(path: Path, findings: list[Finding], verdict: int, as_json: bool) -> None:
if as_json:
print(
json.dumps(
{"entry": str(path), "verdict": verdict, "findings": [f.as_dict() for f in findings]},
indent=2,
)
)
return
if not findings:
print(f"OK {path}")
return
print(f"{'FAULT' if verdict == 1 else 'CNG '} {path}")
for f in findings:
where = f"line {f.line}" if f.line else "entry"
print(f" [{f.code}] ({where}) {f.message}")
def scan(root: Path, *, run: bool, timeout: float, as_json: bool) -> int:
"""Gate over a corpus: every file under root carrying a top-level CHECK line."""
if not root.is_dir():
print(f"{PROG}: --scan: not a directory: {root}", file=sys.stderr)
return 2
checked = faulty = clean = skipped = 0
results: list[dict] = []
for dirpath, dirnames, filenames in os.walk(root):
dirnames[:] = [d for d in dirnames if d not in SKIP_DIRS]
for name in sorted(filenames):
p = Path(dirpath) / name
try:
text = read_text(p)
except (OSError, ValueError):
skipped += 1
continue
if not find_check_lines(text):
continue
checked += 1
findings, verdict = grade(text, run=run, timeout=timeout)
if verdict == 0:
clean += 1
else:
faulty += 1
results.append(
{"entry": str(p), "verdict": verdict, "findings": [f.as_dict() for f in findings]}
)
report(p, findings, verdict, as_json)
if as_json:
print(json.dumps({"root": str(root), "checked": checked, "clean": clean,
"faulty": faulty, "skipped": skipped, "results": results}, indent=2))
else:
print(
f"\nscan {root}: {checked} file(s) with a CHECK line, "
f"{clean} clean, {faulty} faulty, {skipped} unreadable/binary skipped"
)
if faulty:
return 1
return 0
def main(argv: list[str] | None = None) -> int:
ap = argparse.ArgumentParser(
prog=PROG,
description="Lint the CHECK line of a standup entry; its exit code is the verdict.",
)
ap.add_argument("entries", nargs="*", help="entry files to lint")
ap.add_argument("--run", action="store_true",
help="execute the extracted command and fold its real exit code in")
ap.add_argument("--timeout", type=float, default=DEFAULT_TIMEOUT, metavar="SECONDS",
help=f"timeout for --run (default {DEFAULT_TIMEOUT:g}s)")
ap.add_argument("--json", action="store_true", help="emit findings as JSON")
ap.add_argument("--scan", metavar="DIR", help="lint every file under DIR with a CHECK line")
args = ap.parse_args(argv)
if args.scan:
return scan(Path(args.scan), run=args.run, timeout=args.timeout, as_json=args.json)
if not args.entries:
ap.print_usage(sys.stderr)
print(f"{PROG}: no entry given (or use --scan DIR)", file=sys.stderr)
return 2
verdict = 0
for entry in args.entries:
path = Path(entry)
try:
text = read_text(path)
except OSError as exc:
print(f"CNG {path}\n [UNREADABLE] {exc}", file=sys.stderr)
verdict = 2
continue
except ValueError as exc:
print(f"CNG {path}\n [UNREADABLE] {exc}", file=sys.stderr)
verdict = 2
continue
findings, v = grade(text, run=args.run, timeout=args.timeout)
report(path, findings, v, args.json)
if v == 2:
verdict = 2
elif v == 1 and verdict != 2:
verdict = 1
return verdict
if __name__ == "__main__":
sys.exit(main())