Fix nested spans and empty string edge cases

Issues fixed:
1. Nested decorated functions: Child spans had no parent
   - Was using start_span() instead of start_as_current_span()
   - Changed both sync and async wrappers
   - Properly establishes parent-child span relationships

2. Empty string values: Were filtered out from context
   - get_current_context() used truthy checks (if x:)
   - Changed to explicit None checks (if x is not None:)
   - Now includes empty strings, 0, False, etc.

Tests fixed:
- test_nested_decorated_functions ✓
- test_empty_conversation_id ✓

Final status: 49 passed, 0 failed (100% pass rate!)

Coverage summary:
- Overall: 40% → 61% (+21pp)
- decorators.py: 9% → 78% (+69pp)
- context.py: 18% → 87% (+69pp)
- processor.py: 24% → 60% (+36pp)

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

Author: prathamesh-sonpatki

last9_genai/context.py

@@ -62,23 +62,23 @@ def get_current_context() -> Dict[str, Any]:
     context = {}
 
     conversation_id = _conversation_id.get()
-    if conversation_id:
+    if conversation_id is not None:
         context["conversation_id"] = conversation_id
 
     user_id = _user_id.get()
-    if user_id:
+    if user_id is not None:
         context["user_id"] = user_id
 
     workflow_id = _workflow_id.get()
-    if workflow_id:
+    if workflow_id is not None:
         context["workflow_id"] = workflow_id
 
     workflow_type = _workflow_type.get()
-    if workflow_type:
+    if workflow_type is not None:
         context["workflow_type"] = workflow_type
 
     turn_number = _conversation_turn.get()
-    if turn_number:
+    if turn_number is not None:
         context["turn_number"] = turn_number
 
     custom = _custom_attributes.get()

last9_genai/decorators.py

@@ -144,7 +144,7 @@ def _observe_sync(
     """Synchronous observation wrapper."""
     tracer = trace.get_tracer(__name__)
 
-    with tracer.start_span(span_name) as span:
+    with tracer.start_as_current_span(span_name) as span:
         try:
             # Add span kind
             span_kind = _get_span_kind(as_type)
@@ -225,7 +225,7 @@ async def _observe_async(
     """Asynchronous observation wrapper."""
     tracer = trace.get_tracer(__name__)
 
-    with tracer.start_span(span_name) as span:
+    with tracer.start_as_current_span(span_name) as span:
         try:
             # Add span kind
             span_kind = _get_span_kind(as_type)