feat(bluesky): add Bluesky/AT Protocol as social source

Free, no-auth-required search via public.api.bsky.app.
Always-on like HN and Polymarket (no API key needed).

- New scripts/lib/bluesky.py: search + parse via AT Protocol
- BlueskyItem schema, normalization, scoring, deduplication
- Wired into orchestrator ThreadPoolExecutor with timeout config
- Rendering in compact, full, and JSON output modes
- 14 unit tests covering parsing, dates, relevance, edge cases
- --search=bluesky / --search=bsky for bluesky-only mode

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

scripts/lib/bluesky.py

@@ -0,0 +1,166 @@
+"""Bluesky search via AT Protocol (free, no auth required).
+
+Uses public.api.bsky.app for post discovery.
+No API key needed - just HTTP calls via stdlib urllib.
+"""
+
+import math
+import re
+import sys
+from datetime import datetime, timezone
+from typing import Any, Dict, List, Optional
+
+from . import http
+
+BSKY_SEARCH_URL = "https://public.api.bsky.app/xrpc/app.bsky.feed.searchPosts"
+
+DEPTH_CONFIG = {
+    "quick": 15,
+    "default": 30,
+    "deep": 60,
+}
+
+
+def _log(msg: str):
+    """Log to stderr (only in TTY mode to avoid cluttering Claude Code output)."""
+    if sys.stderr.isatty():
+        sys.stderr.write(f"[Bluesky] {msg}\n")
+        sys.stderr.flush()
+
+
+def _extract_core_subject(topic: str) -> str:
+    """Extract core subject from verbose query for Bluesky search."""
+    text = topic.lower().strip()
+    prefixes = [
+        'what are the best', 'what is the best', 'what are the latest',
+        'what are people saying about', 'what do people think about',
+        'how do i use', 'how to use', 'how to',
+        'what are', 'what is', 'tips for', 'best practices for',
+    ]
+    for p in prefixes:
+        if text.startswith(p + ' '):
+            text = text[len(p):].strip()
+    noise = {
+        'best', 'top', 'good', 'great', 'awesome',
+        'latest', 'new', 'news', 'update', 'updates',
+        'trending', 'hottest', 'popular', 'viral',
+        'practices', 'features', 'recommendations', 'advice',
+    }
+    words = text.split()
+    filtered = [w for w in words if w not in noise]
+    result = ' '.join(filtered) if filtered else text
+    return result.rstrip('?!.')
+
+
+def _parse_date(item: Dict[str, Any]) -> Optional[str]:
+    """Parse date from Bluesky post to YYYY-MM-DD.
+
+    AT Protocol uses ISO 8601 format in indexedAt and createdAt fields.
+    """
+    for key in ("indexedAt", "createdAt"):
+        val = item.get(key)
+        if val and isinstance(val, str):
+            try:
+                dt = datetime.fromisoformat(val.replace("Z", "+00:00"))
+                return dt.strftime("%Y-%m-%d")
+            except (ValueError, TypeError):
+                pass
+    return None
+
+
+def search_bluesky(
+    topic: str,
+    from_date: str,
+    to_date: str,
+    depth: str = "default",
+) -> Dict[str, Any]:
+    """Search Bluesky via AT Protocol public API.
+
+    Args:
+        topic: Search topic
+        from_date: Start date (YYYY-MM-DD)
+        to_date: End date (YYYY-MM-DD)
+        depth: 'quick', 'default', or 'deep'
+
+    Returns:
+        Dict with 'posts' list from AT Protocol response.
+    """
+    count = DEPTH_CONFIG.get(depth, DEPTH_CONFIG["default"])
+    core_topic = _extract_core_subject(topic)
+
+    _log(f"Searching for '{core_topic}' (depth={depth}, limit={count})")
+
+    from urllib.parse import urlencode
+    params = {
+        "q": core_topic,
+        "limit": str(min(count, 100)),
+        "sort": "top",
+    }
+    url = f"{BSKY_SEARCH_URL}?{urlencode(params)}"
+
+    try:
+        response = http.request("GET", url, timeout=30)
+    except http.HTTPError as e:
+        _log(f"Search failed: {e}")
+        return {"posts": [], "error": str(e)}
+    except Exception as e:
+        _log(f"Search failed: {e}")
+        return {"posts": [], "error": str(e)}
+
+    posts = response.get("posts", [])
+    _log(f"Found {len(posts)} posts")
+    return response
+
+
+def parse_bluesky_response(response: Dict[str, Any]) -> List[Dict[str, Any]]:
+    """Parse AT Protocol response into normalized item dicts.
+
+    Returns:
+        List of item dicts ready for normalization.
+    """
+    posts = response.get("posts", [])
+    items = []
+
+    for i, post in enumerate(posts):
+        record = post.get("record") or {}
+        text = record.get("text") or ""
+
+        author = post.get("author") or {}
+        handle = author.get("handle") or ""
+        display_name = author.get("displayName") or handle
+
+        # Post URI -> URL
+        # URI format: at://did:plc:xxx/app.bsky.feed.post/rkey
+        uri = post.get("uri") or ""
+        rkey = uri.rsplit("/", 1)[-1] if uri else ""
+        url = f"https://bsky.app/profile/{handle}/post/{rkey}" if handle and rkey else ""
+
+        likes = post.get("likeCount") or 0
+        reposts = post.get("repostCount") or 0
+        replies = post.get("replyCount") or 0
+        quotes = post.get("quoteCount") or 0
+
+        date_str = _parse_date(post) or _parse_date(record)
+
+        # Relevance: position-based (AT Protocol sorts by relevance with sort=top)
+        rank_score = max(0.3, 1.0 - (i * 0.02))
+        engagement_boost = min(0.2, math.log1p(likes + reposts) / 40)
+        relevance = min(1.0, rank_score * 0.7 + engagement_boost + 0.1)
+
+        items.append({
+            "handle": handle,
+            "display_name": display_name,
+            "text": text,
+            "url": url,
+            "date": date_str,
+            "engagement": {
+                "likes": likes,
+                "reposts": reposts,
+                "replies": replies,
+                "quotes": quotes,
+            },
+            "relevance": round(relevance, 2),
+            "why_relevant": f"Bluesky: @{handle}: {text[:60]}" if text else f"Bluesky: {handle}",
+        })
+
+    return items