Add instance system guide nav (default off) with overview/options/hedge manual.

EOF

Co-authored-by: Cursor <cursoragent@cursor.com>

lib/instance/instance_system_guide_lib.py

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+"""实例「系统说明」:加载 Markdown,生成 h2 目录与带锚点正文."""
+from __future__ import annotations
+
+import re
+from functools import lru_cache
+from html import escape
+from pathlib import Path
+from typing import Any
+
+from lib.hub.hub_strategy_lib import render_markdown_html
+from lib.paths import REPO_ROOT
+
+
+def system_guide_md_path() -> Path:
+    return REPO_ROOT / "docs" / "系统说明.md"
+
+
+def _slugify(text: str) -> str:
+    raw = re.sub(r"<[^>]+>", "", text or "")
+    raw = re.sub(r"\s+", "-", raw.strip())
+    raw = re.sub(r"[^\w\u4e00-\u9fff\-]+", "", raw)
+    return raw[:80] or "section"
+
+
+def _inject_h2_ids(html: str) -> tuple[str, list[dict[str, str]]]:
+    """为 h2 注入 id,并收集目录(仅 h2)."""
+    toc: list[dict[str, str]] = []
+    used: dict[str, int] = {}
+
+    def repl(m: re.Match[str]) -> str:
+        inner = m.group(1)
+        base = _slugify(inner)
+        n = used.get(base, 0) + 1
+        used[base] = n
+        hid = base if n == 1 else f"{base}-{n}"
+        toc.append({"id": hid, "title": re.sub(r"<[^>]+>", "", inner).strip()})
+        return f'<h2 id="{escape(hid)}">{inner}</h2>'
+
+    out = re.sub(r"<h2>(.*?)</h2>", repl, html, flags=re.I | re.S)
+    return out, toc
+
+
+@lru_cache(maxsize=4)
+def _load_payload_cached(mtime_ns: int, path_str: str) -> dict[str, Any]:
+    path = Path(path_str)
+    try:
+        md_text = path.read_text(encoding="utf-8")
+    except OSError:
+        md_text = "# 系统说明缺失\n\n未找到 `docs/系统说明.md`。"
+    body = render_markdown_html(md_text)
+    body, toc = _inject_h2_ids(body)
+    return {"html": body, "toc": toc, "mtime_ns": mtime_ns}
+
+
+def load_system_guide_payload() -> dict[str, Any]:
+    path = system_guide_md_path()
+    try:
+        mtime_ns = path.stat().st_mtime_ns
+    except OSError:
+        mtime_ns = 0
+    return dict(_load_payload_cached(mtime_ns, str(path)))
+
+
+def system_guide_template_context() -> dict[str, Any]:
+    payload = load_system_guide_payload()
+    return {
+        "system_guide_html": payload.get("html") or "",
+        "system_guide_toc": payload.get("toc") or [],
+    }