diff --git a/src/readme2demo/llm.py b/src/readme2demo/llm.py
index fb0d7bf..d6e644c 100644
--- a/src/readme2demo/llm.py
+++ b/src/readme2demo/llm.py
@@ -463,7 +463,7 @@ def complete(system: str, user: str, model: str, max_tokens: int = 8192) -> LLMR
 
 def extract_json(text: str) -> str:
     """Pull the first JSON object out of a response (handles ```json fences)."""
-    fence = re.search(r"```(?:json)?\s*\n(.*?)```", text, re.DOTALL)
+    fence = re.search(r"```(?:json)?\s*(.*?)\s*```", text, re.DOTALL)
     if fence:
         return fence.group(1).strip()
     start = text.find("{")
diff --git a/tests/test_llm_backend.py b/tests/test_llm_backend.py
index 250b379..94c8148 100644
--- a/tests/test_llm_backend.py
+++ b/tests/test_llm_backend.py
@@ -321,6 +321,12 @@ def test_anthropic_default_model_matches_config():
     assert llm.PROVIDERS["anthropic"].default_model == Config().model
 
 
+def test_extract_json_accepts_single_line_fenced_json():
+    text = 'diagnostic {not json} ```json {"ok": true}```'
+
+    assert llm.extract_json(text) == '{"ok": true}'
+
+
 # -- openai backend -----------------------------------------------------------------