fix: 4 bugs found in full E2E usage testing

Bug 1: Reddit 403 due to short User-Agent in proxy test
  Root cause: configure proxy test used 'Mozilla/5.0' (too short, Reddit rejects)
  Fix: use full UA string matching the channel implementation

Bug 2: Reddit URL parsing broke on trailing slashes
  Root cause: url.rstrip('/') + '.json' mangled URLs with query params
  Fix: properly parse URL, clean path, reconstruct json URL

Bug 3: Reddit 403 without proxy showed raw HTTP error
  Root cause: no error handling for 403/429 responses
  Fix: friendly message suggesting proxy setup + Exa search alternative

Bug 4: XiaoHongShu without cookie showed Jina Reader 451 error
  Root cause: fallback to Jina Reader which can't access XHS (legal block)
  Fix: show clear message about needing cookies with setup instructions

Bug 5: Empty search query caused raw 422 API error
  Root cause: no input validation before API call
  Fix: check for empty query, show friendly message

All 36 unit tests passing.

agent_eyes/channels/reddit.py

@@ -27,19 +27,39 @@ class RedditChannel(Channel):
         proxy = config.get("reddit_proxy") if config else None
         proxies = {"http": proxy, "https": proxy} if proxy else None
 
-        # Ensure URL ends with .json
-        json_url = url.rstrip("/")
-        if not json_url.endswith(".json"):
-            json_url += ".json"
+        # Clean URL: remove query params, trailing slash, then add .json
+        parsed = urlparse(url)
+        clean_path = parsed.path.rstrip("/")
+        # Remove trailing .json if already present (avoid double .json)
+        if clean_path.endswith(".json"):
+            clean_path = clean_path[:-5]
+        json_url = f"https://www.reddit.com{clean_path}.json"
+
+        try:
+            resp = requests.get(
+                json_url,
+                headers={"User-Agent": self.USER_AGENT},
+                proxies=proxies,
+                params={"limit": 50},
+                timeout=15,
+            )
+            resp.raise_for_status()
+        except requests.exceptions.HTTPError as e:
+            status = e.response.status_code if e.response is not None else 0
+            if status in (403, 429):
+                return ReadResult(
+                    title="Reddit",
+                    content="⚠️ Reddit blocked this request (403 Forbidden). "
+                            "Reddit blocks most server IPs.\n"
+                            "Fix: agent-eyes configure proxy http://user:pass@ip:port\n"
+                            "Cheap option: https://www.webshare.io ($1/month)\n\n"
+                            "Alternatively, search Reddit via Exa (free, no proxy needed): "
+                            "agent-eyes search-reddit \"your query\"",
+                    url=url,
+                    platform="reddit",
+                )
+            raise
 
-        resp = requests.get(
-            json_url,
-            headers={"User-Agent": self.USER_AGENT},
-            proxies=proxies,
-            params={"limit": 50},
-            timeout=15,
-        )
-        resp.raise_for_status()
         data = resp.json()
 
         if isinstance(data, list) and len(data) >= 1:

agent_eyes/channels/xiaohongshu.py

@@ -27,9 +27,14 @@ class XiaoHongShuChannel(Channel):
         cookie = config.get("xhs_cookie") if config else None
 
         if not cookie:
-            # Fallback to Jina Reader (works for some public notes)
-            from agent_eyes.channels.web import WebChannel
-            return await WebChannel().read(url, config)
+            return ReadResult(
+                title="XiaoHongShu",
+                content="⚠️ XiaoHongShu requires cookies to access.\n"
+                        "Set up: agent-eyes configure xhs-cookie \"YOUR_COOKIE_STRING\"\n"
+                        "How to get it: install Cookie-Editor extension → go to xiaohongshu.com → Export → Header String",
+                url=url,
+                platform="xiaohongshu",
+            )
 
         # Extract note ID from URL
         note_id = self._extract_note_id(url)