fix(skill_engine): parse LLM JSON despite trailing brace prose

Greedy \{.*\} matching spanned into later prose braces, so json.loads
failed and analysis/capture dropped valid objects. Use raw_decode from
the first brace, matching agents.base.

.gitignore

@@ -51,6 +51,7 @@ tests/skill_engine/*
 !tests/skill_engine/test_evolver_length_recovery.py
 !tests/skill_engine/test_evolution_retry_idempotency.py
 !tests/skill_engine/test_analyzer_length_recovery.py
+!tests/skill_engine/test_extract_json_trailing_prose.py
 !tests/skill_engine/decision/
 tests/skill_engine/decision/*
 !tests/skill_engine/decision/test_analysis_adapter.py

openspace/skill_engine/analyzer.py

@@ -1508,13 +1508,13 @@ class ExecutionAnalyzer:
         if code_match:
             text = code_match.group(1).strip()
         else:
-            # Try bare JSON object
-            json_match = re.search(r"\{.*\}", text, re.DOTALL)
-            if json_match:
-                text = json_match.group()
+            # Prefer the first object start; raw_decode ignores trailing prose.
+            brace = text.find("{")
+            if brace >= 0:
+                text = text[brace:]
 
         try:
-            data = json.loads(text)
+            data, _ = json.JSONDecoder().raw_decode(text)
             if isinstance(data, dict):
                 return data
             logger.warning(f"LLM returned non-dict JSON: {type(data)}")

openspace/skill_engine/evolution/capture_semantic.py

@@ -399,11 +399,13 @@ def _extract_json(text: str) -> dict[str, Any] | None:
     if match:
         text = match.group(1)
     else:
-        match = re.search(r"\{.*\}", text, re.DOTALL)
-        if match:
-            text = match.group(0)
+        brace = text.find("{")
+        if brace >= 0:
+            text = text[brace:]
+        else:
+            return None
     try:
-        value = json.loads(text)
+        value, _ = json.JSONDecoder().raw_decode(text)
     except Exception:
         return None
     return dict(value) if isinstance(value, Mapping) else None

tests/skill_engine/test_extract_json_trailing_prose.py

@@ -0,0 +1,16 @@
+"""Regression: trailing prose with braces must not drop valid analysis JSON."""
+
+from __future__ import annotations
+
+from openspace.skill_engine.analyzer import ExecutionAnalyzer
+from openspace.skill_engine.evolution.capture_semantic import _extract_json as capture_extract_json
+
+
+def test_analyzer_extract_json_tolerates_trailing_prose_braces():
+    text = '{"task_completed": true}\n\nReplace {foo} with {bar}.'
+    assert ExecutionAnalyzer._extract_json(text) == {"task_completed": True}
+
+
+def test_capture_semantic_extract_json_tolerates_trailing_prose_braces():
+    text = '{"ok": true}\n\nnote {x}'
+    assert capture_extract_json(text) == {"ok": True}