Handle unknown lexer, remove dead _THEMES list, tighten JSON detection - Catch unknown Pygments lexer names and fall back to plain text - Remove unused _THEMES list from cli.py - Only auto-detect JSON when content starts with { or [ to avoid false positives on trivial values like strings or numbers

src/rp/detect.py

@@ -73,10 +73,12 @@ def detect_type(
             return EXTENSION_MAP[suffix]
 
     if content is not None:
-        try:
-            json.loads(content[:1000])
-            return "json"
-        except (json.JSONDecodeError, ValueError):
-            pass
+        stripped = content.lstrip()
+        if stripped and stripped[0] in ("{", "["):
+            try:
+                json.loads(stripped[:1000])
+                return "json"
+            except (json.JSONDecodeError, ValueError):
+                pass
 
     return "text"