Deliver explainability triples inline in retrieval response stream (#763)

Provenance triples are now included directly in explain messages from
GraphRAG, DocumentRAG, and Agent services, eliminating the need for
follow-up knowledge graph queries to retrieve explainability details.

Each explain message in the response stream now carries:
- explain_id: root URI for this provenance step (unchanged)
- explain_graph: named graph where triples are stored (unchanged)
- explain_triples: the actual provenance triples for this step (new)

Changes across the stack:
- Schema: added explain_triples field to GraphRagResponse,
  DocumentRagResponse, and AgentResponse
- Services: all explain message call sites pass triples through
  (graph_rag, document_rag, agent react, agent orchestrator)
- Translators: encode explain_triples via TripleTranslator for
  gateway wire format
- Python SDK: ProvenanceEvent now includes parsed ExplainEntity
  and raw triples; expanded event_type detection
- CLI: invoke_graph_rag, invoke_agent, invoke_document_rag use
  inline entity when available, fall back to graph query
- Tech specs updated

Additional explainability test

trustgraph-flow/trustgraph/agent/orchestrator/pattern_base.py

@@ -243,6 +243,7 @@ class PatternBase:
             content="",
             explain_id=session_uri,
             explain_graph=GRAPH_RETRIEVAL,
+            explain_triples=triples,
         ))
 
     async def emit_iteration_triples(self, flow, session_id, iteration_num,
@@ -305,6 +306,7 @@ class PatternBase:
             content="",
             explain_id=iteration_uri,
             explain_graph=GRAPH_RETRIEVAL,
+            explain_triples=iter_triples,
         ))
 
     async def emit_observation_triples(self, flow, session_id, iteration_num,
@@ -360,6 +362,7 @@ class PatternBase:
             content="",
             explain_id=observation_entity_uri,
             explain_graph=GRAPH_RETRIEVAL,
+            explain_triples=obs_triples,
         ))
 
     async def emit_final_triples(self, flow, session_id, iteration_num,
@@ -416,6 +419,7 @@ class PatternBase:
             content="",
             explain_id=final_uri,
             explain_graph=GRAPH_RETRIEVAL,
+            explain_triples=final_triples,
         ))
 
     # ---- Orchestrator provenance helpers ------------------------------------
@@ -437,6 +441,7 @@ class PatternBase:
         await respond(AgentResponse(
             chunk_type="explain", content="",
             explain_id=uri, explain_graph=GRAPH_RETRIEVAL,
+            explain_triples=triples,
         ))
 
     async def emit_finding_triples(
@@ -475,6 +480,7 @@ class PatternBase:
         await respond(AgentResponse(
             chunk_type="explain", content="",
             explain_id=uri, explain_graph=GRAPH_RETRIEVAL,
+            explain_triples=triples,
         ))
 
     async def emit_plan_triples(
@@ -494,6 +500,7 @@ class PatternBase:
         await respond(AgentResponse(
             chunk_type="explain", content="",
             explain_id=uri, explain_graph=GRAPH_RETRIEVAL,
+            explain_triples=triples,
         ))
 
     async def emit_step_result_triples(
@@ -526,6 +533,7 @@ class PatternBase:
         await respond(AgentResponse(
             chunk_type="explain", content="",
             explain_id=uri, explain_graph=GRAPH_RETRIEVAL,
+            explain_triples=triples,
         ))
 
     async def emit_synthesis_triples(
@@ -557,6 +565,7 @@ class PatternBase:
         await respond(AgentResponse(
             chunk_type="explain", content="",
             explain_id=uri, explain_graph=GRAPH_RETRIEVAL,
+            explain_triples=triples,
         ))
 
     # ---- Response helpers ---------------------------------------------------

trustgraph-flow/trustgraph/agent/react/service.py

@@ -473,6 +473,7 @@ class Processor(AgentService):
                     content="",
                     explain_id=session_uri,
                     explain_graph=GRAPH_RETRIEVAL,
+                    explain_triples=triples,
                 ))
 
             logger.info(f"Question: {request.question}")
@@ -640,6 +641,7 @@ class Processor(AgentService):
                     content="",
                     explain_id=iter_uri,
                     explain_graph=GRAPH_RETRIEVAL,
+                    explain_triples=iter_triples,
                 ))
 
             user_context = UserAwareContext(flow, request.user)
@@ -717,6 +719,7 @@ class Processor(AgentService):
                     content="",
                     explain_id=final_uri,
                     explain_graph=GRAPH_RETRIEVAL,
+                    explain_triples=final_triples,
                 ))
 
                 if streaming:
@@ -793,6 +796,7 @@ class Processor(AgentService):
                 content="",
                 explain_id=observation_entity_uri,
                 explain_graph=GRAPH_RETRIEVAL,
+                explain_triples=obs_triples,
             ))
 
             history.append(act)

trustgraph-flow/trustgraph/retrieval/document_rag/rag.py

@@ -162,12 +162,13 @@ class Processor(FlowProcessor):
                     triples=triples,
                 ))
 
-                # Send explain ID and graph to response queue
+                # Send explain data to response queue
                 await flow("response").send(
                     DocumentRagResponse(
                         response=None,
                         explain_id=explain_id,
                         explain_graph=GRAPH_RETRIEVAL,
+                        explain_triples=triples,
                         message_type="explain",
                     ),
                     properties={"id": id}

trustgraph-flow/trustgraph/retrieval/graph_rag/rag.py

@@ -253,12 +253,13 @@ class Processor(FlowProcessor):
                     triples=triples,
                 ))
 
-                # Send explain ID and graph to response queue
+                # Send explain data to response queue
                 await flow("response").send(
                     GraphRagResponse(
                         message_type="explain",
                         explain_id=explain_id,
                         explain_graph=GRAPH_RETRIEVAL,
+                        explain_triples=triples,
                     ),
                     properties={"id": id}
                 )