Wire up query history: localStorage session persistence + sidebar UI

apps/ai-service/adapters/postgres.py

@@ -20,6 +20,7 @@ class RetrievalTrace:
     citations: tuple[dict[str, Any], ...]
     correlation_id: str | None = None
     otel_trace_id: str | None = None
+    conversation_id: str | None = None
     created_at: datetime | None = None
 
 
@@ -63,6 +64,7 @@ class PostgresTraceRepository:
         citations: tuple[dict[str, Any], ...],
         correlation_id: str | None = None,
         otel_trace_id: str | None = None,
+        conversation_id: str | None = None,
     ) -> str:
         import psycopg
 
@@ -73,13 +75,13 @@ class PostgresTraceRepository:
                 INSERT INTO rag_retrieval_trace (
                     trace_id, query_text, subject_scope, query_intent,
                     decision, reason, resolved_drug_id, citations,
-                    correlation_id, otel_trace_id
-                ) VALUES (%s, %s, %s, %s, %s, %s, %s, %s::jsonb, %s, %s)
+                    correlation_id, otel_trace_id, conversation_id
+                ) VALUES (%s, %s, %s, %s, %s, %s, %s, %s::jsonb, %s, %s, %s)
                 """,
                 (
                     trace_id, query, subject_scope, intent, decision, reason,
                     resolved_drug_id, json.dumps(citations, ensure_ascii=False),
-                    correlation_id, otel_trace_id,
+                    correlation_id, otel_trace_id, conversation_id,
                 ),
             )
         return trace_id
@@ -92,7 +94,7 @@ class PostgresTraceRepository:
                 """
                 SELECT trace_id::text, query_text, subject_scope, query_intent,
                        decision, reason, resolved_drug_id, citations,
-                       correlation_id, otel_trace_id, created_at
+                       correlation_id, otel_trace_id, conversation_id, created_at
                 FROM rag_retrieval_trace WHERE trace_id = %s
                 """,
                 (trace_id,),
@@ -103,9 +105,46 @@ class PostgresTraceRepository:
             trace_id=row[0], query=row[1], subject_scope=row[2], intent=row[3],
             decision=row[4], reason=row[5], resolved_drug_id=row[6],
             citations=tuple(row[7]), correlation_id=row[8], otel_trace_id=row[9],
-            created_at=row[10],
+            conversation_id=row[10], created_at=row[11],
         )
 
+    def list_by_conversation(
+        self, conversation_id: str, limit: int
+    ) -> list[RetrievalTrace]:
+        """Past queries for one session — Feature-List #25 (lịch sử tra
+        cứu), most recent first. Scoped to `conversation_id` on purpose:
+        this system has no auth anywhere (`apps/api-gateway`/`auth-service`
+        are unbuilt — see README), so an unscoped listing would mix every
+        browser's/user's queries together. Citations/answer text are NOT
+        persisted here (only decision/reason/resolved_drug_id) — a history
+        entry is for re-running the same query, not replaying its old
+        answer verbatim.
+        """
+        import psycopg
+
+        with psycopg.connect(self._dsn, connect_timeout=5) as connection:
+            rows = connection.execute(
+                """
+                SELECT trace_id::text, query_text, subject_scope, query_intent,
+                       decision, reason, resolved_drug_id, citations,
+                       correlation_id, otel_trace_id, conversation_id, created_at
+                FROM rag_retrieval_trace
+                WHERE conversation_id = %s
+                ORDER BY created_at DESC
+                LIMIT %s
+                """,
+                (conversation_id, limit),
+            ).fetchall()
+        return [
+            RetrievalTrace(
+                trace_id=row[0], query=row[1], subject_scope=row[2], intent=row[3],
+                decision=row[4], reason=row[5], resolved_drug_id=row[6],
+                citations=tuple(row[7]), correlation_id=row[8], otel_trace_id=row[9],
+                conversation_id=row[10], created_at=row[11],
+            )
+            for row in rows
+        ]
+
     def save_feedback(
         self,
         *,