214 lines
8.7 KiB
Python
Executable File
214 lines
8.7 KiB
Python
Executable File
#!/usr/bin/env python3
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"""Differential replay harness for the macOS HOST surface (docs/NASH.md §10.6 — the M5.5 gate).
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The host risk is *semantic divergence*, not parse failure: a command that parses under nash but
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means something different under zsh (unquoted word splitting, no-match globbing) runs to
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completion with different results and no fallback event. So this harness replays each corpus
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command under BOTH `zsh -lc` (today's host shell) and `nash -c` (the M5.5 flip: login sourcing is
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replaced by the LoginShellEnv snapshot, hence `-c`) in identical disposable workspaces, then
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diffs exit code, stdout, AND the resulting file-system tree. stderr is compared separately and
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never counts against parity (error wording legitimately differs).
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Corpus entries (host-corpus.jsonl, one JSON object per line):
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{"id": "...", "cmd": "...", # a replayable command
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"class": "replayable" | "excluded:<reason>", # exclusions are REPORTED, never silent
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"expect": "match" | "diverge"} # 'diverge' = harness SELF-TEST entry: a known
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# zsh≠bash-family semantic difference the
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# diff engine MUST catch (else the engine is
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# blind and the gate is meaningless)
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Workspaces: a synthetic fixture tree by default; pass --worktree PATH to clone a real project
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tree instead (cp -R into the scratch dir) so toolchain commands (`swift build`, `make`) replay
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against real inputs — §10.6's "disposable clone".
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Verifying the harness before a darwin nash exists: `--nash /bin/bash` is a faithful stand-in for
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the divergence semantics under test (bash word-splits and passes unmatched globs through exactly
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as nash's brush core does; zsh does neither), so the self-test entries must report DIVERGE and
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real entries' verdicts are meaningful. The real gate run uses the built nash.
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Exit status: 0 iff every replayable expect-match entry matched AND every expect-diverge
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self-test diverged AND at least one self-test ran.
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"""
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import argparse
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import hashlib
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import json
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import os
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import shutil
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import subprocess
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import sys
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import tempfile
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FIXTURES = {
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"a.txt": "first line\nsecond line\nthird line\n",
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"b.txt": "banana\napple\nbanana\ncherry\napple\n",
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"data.csv": "name,team,score\nalice,red,10\nbob,blue,7\ncarol,red,9\ndave,blue,7\n",
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"logs/app.log": (
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"2026-01-01 INFO boot ok\n"
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"2026-01-01 ERROR disk full\n"
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"2026-01-01 INFO retry\n"
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"2026-01-01 WARN slow\n"
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"2026-01-01 ERROR net down\n"
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"2026-01-01 INFO done\n"
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),
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"src/main.py": "print('main')\n",
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"src/util.py": "def add(a, b):\n return a + b\n",
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"README.md": "# Sample\n",
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"Makefile": "check:\n\t@echo make-ran\n",
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}
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TIMEOUT_S = 60
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def seed(workdir, worktree=None):
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if worktree:
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shutil.copytree(worktree, workdir, symlinks=True, dirs_exist_ok=True)
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return
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for rel, content in FIXTURES.items():
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path = os.path.join(workdir, rel)
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os.makedirs(os.path.dirname(path), exist_ok=True)
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with open(path, "w") as f:
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f.write(content)
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def snapshot(workdir):
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"""Relative path -> sha256 of contents, for every file in the tree."""
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out = {}
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for root, _dirs, files in os.walk(workdir):
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for name in files:
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path = os.path.join(root, name)
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rel = os.path.relpath(path, workdir)
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try:
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with open(path, "rb") as f:
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out[rel] = hashlib.sha256(f.read()).hexdigest()
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except OSError:
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out[rel] = "<unreadable>"
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return out
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def run_one(shell, mode, cmd, worktree=None):
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parent = tempfile.mkdtemp(prefix="nash-hostdiff-")
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workdir = os.path.join(parent, "workspace")
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os.makedirs(workdir, exist_ok=True)
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seed(workdir, worktree)
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# A pinned, minimal env on purpose: the point of §7.7.2 is that the flip must NOT depend on
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# what login sourcing would add — a command that only works under `zsh -lc`'s rc-sourced env
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# shows up here as a divergence to investigate, which is the gate doing its job.
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env = {
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"PATH": "/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin",
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"HOME": workdir,
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"LC_ALL": "C",
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"LANG": "C",
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"TERM": "dumb",
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"SHELL": shell,
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}
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try:
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proc = subprocess.run(
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[shell, mode, cmd], cwd=workdir, env=env, capture_output=True, timeout=TIMEOUT_S
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)
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code, out, err = proc.returncode, proc.stdout, proc.stderr
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except subprocess.TimeoutExpired:
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code, out, err = "TIMEOUT", b"", b""
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fs = snapshot(workdir)
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shutil.rmtree(parent, ignore_errors=True)
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def norm(b):
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text = b.decode("utf-8", "replace")
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return text.replace(workdir, "__WORK__").replace(parent, "__TMP__")
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return {"code": code, "stdout": norm(out), "stderr": norm(err), "fs": fs}
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def classify_outcome(z, n):
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core_equal = (
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z["code"] == n["code"] and z["stdout"] == n["stdout"] and z["fs"] == n["fs"]
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)
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if core_equal and z["stderr"] == n["stderr"]:
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return "MATCH"
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if core_equal:
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return "STDERR_ONLY"
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return "DIVERGE"
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def main():
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ap = argparse.ArgumentParser()
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ap.add_argument("--nash", default=os.environ.get("NASH_BIN", "nash"),
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help="nash binary (or /bin/bash as a semantics stand-in pre-nash)")
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ap.add_argument("--zsh", default="/bin/zsh")
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ap.add_argument(
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"--corpus",
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default=os.path.join(
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os.path.dirname(os.path.abspath(__file__)), "host-corpus.jsonl"),
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)
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ap.add_argument("--worktree", help="clone this tree as the workspace (disposable copy)")
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ap.add_argument("--json", help="also write the full report to this path")
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args = ap.parse_args()
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entries = []
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with open(args.corpus) as f:
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for line in f:
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line = line.strip()
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if line:
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entries.append(json.loads(line))
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excluded = [e for e in entries if e.get("class", "replayable").startswith("excluded:")]
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replayable = [e for e in entries if e not in excluded]
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results = []
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for entry in replayable:
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z = run_one(args.zsh, "-lc", entry["cmd"], args.worktree)
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n = run_one(args.nash, "-c", entry["cmd"], args.worktree)
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outcome = classify_outcome(z, n)
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expect = entry.get("expect", "match")
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if expect == "diverge":
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verdict = "SELFTEST_OK" if outcome == "DIVERGE" else "SELFTEST_BLIND"
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else:
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verdict = {"MATCH": "PASS", "STDERR_ONLY": "STDERR_ONLY", "DIVERGE": "DIVERGE"}[outcome]
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results.append({
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"id": entry["id"], "cmd": entry["cmd"], "expect": expect,
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"verdict": verdict, "zsh": z, "nash": n,
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})
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marker = {"PASS": ".", "STDERR_ONLY": "s", "DIVERGE": "X",
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"SELFTEST_OK": "+", "SELFTEST_BLIND": "!"}[verdict]
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print(marker, end="", flush=True)
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print()
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diverges = [r for r in results if r["verdict"] == "DIVERGE"]
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blind = [r for r in results if r["verdict"] == "SELFTEST_BLIND"]
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selftests = [r for r in results if r["expect"] == "diverge"]
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gated = [r for r in results if r["expect"] == "match"]
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passes = sum(1 for r in gated if r["verdict"] in ("PASS", "STDERR_ONLY"))
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parity = 100.0 * passes / len(gated) if gated else 0.0
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print(f"\nreplayable: {len(gated)} parity: {passes}/{len(gated)} = {parity:.1f}%"
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f" self-tests: {len(selftests) - len(blind)}/{len(selftests)} caught")
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# Exclusions are part of the report, never silent (§10.6).
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for e in excluded:
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print(f" excluded [{e['class'].split(':', 1)[1]}]: {e['id']}: {e['cmd']!r}")
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for r in diverges + blind:
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print(f"\n{r['verdict']} {r['id']}: {r['cmd']!r}")
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print(f" zsh : code={r['zsh']['code']} stdout={r['zsh']['stdout']!r}")
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print(f" nash: code={r['nash']['code']} stdout={r['nash']['stdout']!r}")
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if r["zsh"]["fs"] != r["nash"]["fs"]:
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only = set(r["zsh"]["fs"]) ^ set(r["nash"]["fs"])
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differs = {
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k for k in set(r["zsh"]["fs"]) & set(r["nash"]["fs"])
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if r["zsh"]["fs"][k] != r["nash"]["fs"][k]
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}
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print(f" fs delta: only-one-side={sorted(only)} content-differs={sorted(differs)}")
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if args.json:
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with open(args.json, "w") as f:
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json.dump({"parity_percent": parity, "results": results,
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"excluded": excluded}, f, indent=1)
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ok = not diverges and not blind and selftests
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if not selftests:
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print("no self-test entries ran — the corpus must keep them (they prove the diff "
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"engine can see semantic divergence)")
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sys.exit(0 if ok else 1)
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if __name__ == "__main__":
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main()
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