news digest (spec-013): rss/atom -> {news} file via cron

Replaces the broken pre-1.0-openai news_feed.py. Stdlib parsing with
defusedxml (feeds are untrusted XML), titles sanitized (SAF-03), feed
URLs SSRF-guarded. CLI: python -m fjerkroa_bot.news --config <cfg>.

fjerkroa_bot/news.py

@@ -0,0 +1,153 @@
+"""News digest fetcher (SPEC-013, FDB-012 news rewrite).
+
+Replaces the broken pre-1.0-openai `news_feed.py`. Fetches configured
+RSS/Atom feeds (stdlib, no feedparser dep), builds a compact sanitized
+headline digest, and writes it to the `{news}` file the responder
+injects (AIResponder.message). Feeds are external input: titles are
+sanitized (SAF-03) and each feed URL is SSRF-guarded before fetching.
+
+CLI: python -m fjerkroa_bot.news --config kroa.toml
+"""
+
+import argparse
+import logging
+import sys
+import time
+from typing import Any, Dict, List, Optional, Tuple
+
+import defusedxml.ElementTree as ElementTree  # hardened XML: feeds are untrusted (XXE/billion-laughs)
+
+from .ai_responder import sanitize_external_text
+
+DEFAULT_PER_FEED = 3
+DEFAULT_MAX_ITEMS = 15
+FETCH_TIMEOUT_S = 15
+_ATOM = "{http://www.w3.org/2005/Atom}"
+
+
+def parse_feed(data: bytes, source: str = "") -> List[Dict[str, str]]:
+    """Parse RSS or Atom bytes into [{title, link, source}] (tolerant)."""
+    try:
+        root = ElementTree.fromstring(data)
+    except Exception as err:
+        # malformed XML or a blocked entity/DTD attack — tolerate, never raise (NEWS-01)
+        logging.warning(f"news: unparseable/unsafe feed {source!r}: {err!r}")
+        return []
+    items: List[Dict[str, str]] = []
+    # RSS: <rss><channel><item><title/><link/>
+    for item in root.iter("item"):
+        title = (item.findtext("title") or "").strip()
+        link = (item.findtext("link") or "").strip()
+        if title:
+            items.append({"title": title, "link": link, "source": source})
+    # Atom: <feed><entry><title/><link href=/>
+    for entry in root.iter(f"{_ATOM}entry"):
+        title = (entry.findtext(f"{_ATOM}title") or "").strip()
+        link_el = entry.find(f"{_ATOM}link")
+        link = link_el.get("href", "") if link_el is not None else ""
+        if title:
+            items.append({"title": title, "link": link, "source": source})
+    return items
+
+
+def render_digest(items: List[Dict[str, str]], max_items: int = DEFAULT_MAX_ITEMS) -> str:
+    """Compact sanitized digest for the {news} prompt slot."""
+    lines = []
+    for item in items[:max_items]:
+        title = sanitize_external_text(item["title"], 200)
+        source = item.get("source", "")
+        link = item.get("link", "")
+        prefix = f"[{source}] " if source else ""
+        lines.append(f"- {prefix}{title}" + (f" ({link})" if link else ""))
+    return "\n".join(lines)
+
+
+class NewsFetcher:
+    def __init__(self, guard, fetch_bytes) -> None:
+        # injected so tests need no network; production wires aiohttp + guard_url
+        self._guard = guard
+        self._fetch_bytes = fetch_bytes
+
+    async def collect(self, feeds: List[Tuple[str, str]], per_feed: int) -> List[Dict[str, str]]:
+        """feeds = [(url, label)]; returns deduped items, order preserved."""
+        seen = set()
+        out: List[Dict[str, str]] = []
+        for url, label in feeds:
+            reason = self._guard(url)
+            if reason:
+                logging.warning(f"news: skipping feed {label} — {reason}")
+                continue
+            try:
+                data = await self._fetch_bytes(url)
+            except Exception as err:
+                logging.warning(f"news: fetch failed for {label}: {repr(err)}")
+                continue
+            for item in parse_feed(data, label)[:per_feed]:
+                key = item["title"]
+                if key not in seen:
+                    seen.add(key)
+                    out.append(item)
+        return out
+
+
+def _feeds_from_config(config: Dict[str, Any]) -> List[Tuple[str, str]]:
+    """news-feeds = [["url", "label"], ...] or ["url", ...]."""
+    feeds = []
+    for entry in config.get("news-feeds", []):
+        if isinstance(entry, (list, tuple)):
+            feeds.append((str(entry[0]), str(entry[1]) if len(entry) > 1 else ""))
+        else:
+            feeds.append((str(entry), ""))
+    return feeds
+
+
+async def _aiohttp_fetch(url: str) -> bytes:
+    import aiohttp
+
+    from .httpread import read_capped
+
+    timeout = aiohttp.ClientTimeout(total=FETCH_TIMEOUT_S)
+    async with aiohttp.ClientSession(timeout=timeout, headers={"User-Agent": "Mozilla/5.0 (compatible; FjerkroaBot-news/1.0)"}) as session:
+        async with session.get(url) as response:
+            response.raise_for_status()
+            return await read_capped(response, 4 * 1024 * 1024)
+
+
+async def run(config: Dict[str, Any]) -> Optional[str]:
+    from .url_reader import guard_url
+
+    out_path = config.get("news")
+    if not out_path:
+        logging.error("news: no `news` output path in config")
+        return None
+    feeds = _feeds_from_config(config)
+    if not feeds:
+        logging.error("news: no `news-feeds` configured")
+        return None
+    fetcher = NewsFetcher(guard_url, _aiohttp_fetch)
+    items = await fetcher.collect(feeds, int(config.get("news-per-feed", DEFAULT_PER_FEED)))
+    digest = render_digest(items, int(config.get("news-max-items", DEFAULT_MAX_ITEMS)))
+    header = f"News as of {time.strftime('%Y-%m-%d %H:%M UTC', time.gmtime())}:\n"
+    with open(out_path, "w", encoding="utf-8") as fd:
+        fd.write(header + digest + "\n")
+    logging.info(f"news: wrote {len(items)} items to {out_path}")
+    return out_path
+
+
+def main() -> int:
+    import asyncio
+
+    import tomlkit
+
+    logging.basicConfig(level=logging.INFO, format="%(asctime)s [%(levelname)s] %(message)s")
+    parser = argparse.ArgumentParser(description="Fetch RSS/Atom feeds into the {news} digest file")
+    parser.add_argument("--config", required=True)
+    args = parser.parse_args()
+    with open(args.config, encoding="utf-8") as fd:
+        config = tomlkit.load(fd)
+    result = asyncio.run(run(config))
+    return 0 if result else 1
+
+
+if __name__ == "__main__":
+    sys.exit(main())