Antigravity 2.17.0 のルール枠 20,000 トークンに、手元の運用ルール集を当てて数えました

#!/usr/bin/env python3
"""Antigravity のルール予算を、手元のルール集で事前に測る小さな道具。
- 24,000 バイト／ファイル（@[label](path) 展開後）を超えるものを警告
- always_on（と frontmatter の無い AGENTS.md / GEMINI.md）の合計を 20,000 トークンと比べる
- 超過時は大きいファイルから順にポインタ化される前提で、どれが残るかを試算
トークンは tiktoken cl100k_base の近似値。Gemini の実カウントとは前後します。
"""
import re, sys, pathlib
import tiktoken
 
FILE_LIMIT_BYTES = 24_000
RULES_BUDGET_TOKENS = 20_000
VALID_TRIGGERS = {"always_on", "model_decision", "glob", "manual"}
enc = tiktoken.get_encoding("cl100k_base")
INCLUDE = re.compile(r"@\[[^\]]*\]\(([^)]+)\)")
 
def expand_includes(text: str, base: pathlib.Path) -> str:
    def repl(m):
        target = pathlib.Path(m.group(1)).expanduser()
        if not target.is_absolute():
            target = (base / target).resolve()
        try:
            body = target.read_text(encoding="utf-8")
        except OSError:
            return m.group(0)  # 見つからないときは原文のまま
        return re.sub(r"\A---\n.*?\n---\n", "", body, flags=re.S)  # frontmatter を落とす
    return INCLUDE.sub(repl, text)
 
def read_rule(path: pathlib.Path):
    raw = path.read_text(encoding="utf-8")
    trigger, desc = None, ""
    m = re.match(r"\A---\n(.*?)\n---\n", raw, flags=re.S)
    if m:
        fm = m.group(1)
        t = re.search(r"^trigger:\s*(\S+)", fm, flags=re.M)
        d = re.search(r'^description:\s*"?(.*?)"?\s*$', fm, flags=re.M)
        trigger = t.group(1) if t else "INVALID"
        if trigger not in VALID_TRIGGERS:
            trigger = "INVALID"  # alwaysOn / modelDecision などは黙って捨てられる
        desc = d.group(1) if d else ""
    elif path.name in ("AGENTS.md", "GEMINI.md"):
        trigger = "always_on"  # frontmatter なしで常時有効
    else:
        trigger = "INVALID"  # rules/ 配下で frontmatter 無し → 黙って捨てられる
    body = expand_includes(raw, path.parent)
    return {"path": path, "trigger": trigger, "desc": desc,
            "bytes": len(body.encode("utf-8")), "tokens": len(enc.encode(body))}
 
def main(root: str):
    root = pathlib.Path(root)
    files = [p for p in (root / "AGENTS.md", root / "GEMINI.md") if p.exists()]
    files += sorted((root / ".agents" / "rules").glob("*.md"))
    rules = [read_rule(p) for p in files]
    active = [r for r in rules if r["trigger"] == "always_on"]
    total = sum(r["tokens"] for r in active)
    print(f"{'file':<28}{'trigger':<16}{'bytes':>8}{'tokens':>8}  note")
    for r in rules:
        note = []
        if r["bytes"] > FILE_LIMIT_BYTES: note.append("OVER 24,000 B -> truncated")
        if r["trigger"] == "INVALID": note.append("discarded (no/invalid frontmatter)")
        print(f"{r['path'].name:<28}{r['trigger']:<16}{r['bytes']:>8}{r['tokens']:>8}  {' / '.join(note)}")
    print(f"\nalways_on total: {total:,} tokens / budget {RULES_BUDGET_TOKENS:,}")
    if total <= RULES_BUDGET_TOKENS:
        print("OK: すべて本文のまま入ります"); return
    demoted, remaining = [], total
    for r in sorted(active, key=lambda r: r["tokens"], reverse=True):
        if remaining <= RULES_BUDGET_TOKENS: break
        demoted.append(r); remaining -= r["tokens"]
    print(f"over by {total - RULES_BUDGET_TOKENS:,}; demoted to pointers (largest first):")
    for r in demoted:
        print(f"  - {r['path'].relative_to(root)}: {r['desc'] or '(description なし)'}")
    print(f"inline after demotion: {remaining:,} tokens")
 
if __name__ == "__main__":
    main(sys.argv[1] if len(sys.argv) > 1 else ".")