feat(search): add structured filters to AI session list endpoint and frontend

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

backend/app/api/endpoints/ai_sessions.py

@@ -11,6 +11,7 @@ CRUD and interaction endpoints for AI-powered troubleshooting sessions:
   POST   /ai-sessions/{id}/rate         — Submit post-session rating
 """
 import logging
+from datetime import datetime
 from typing import Annotated, Optional
 from uuid import UUID
 
@@ -464,6 +465,13 @@ async def list_sessions(
     session_status: Optional[str] = Query(None, alias="status"),
     skip: int = Query(0, ge=0),
     limit: int = Query(20, ge=1, le=100),
+    problem_domain: Optional[str] = Query(None),
+    matched_flow_id: Optional[UUID] = Query(None),
+    confidence_tier: Optional[str] = Query(None, pattern="^(guided|exploring|discovery)$"),
+    ticket_id: Optional[str] = Query(None),
+    date_from: Optional[datetime] = Query(None),
+    date_to: Optional[datetime] = Query(None),
+    q: Optional[str] = Query(None, min_length=2, max_length=200),
 ):
     """List the current user's AI sessions (owned or picked up)."""
     user_id_str = str(current_user.id)
@@ -482,6 +490,19 @@ async def list_sessions(
 
     if session_status:
         query = query.where(AISession.status == session_status)
+    if problem_domain:
+        query = query.where(AISession.problem_domain == problem_domain)
+    if matched_flow_id:
+        query = query.where(AISession.matched_flow_id == matched_flow_id)
+    if confidence_tier:
+        query = query.where(AISession.confidence_tier == confidence_tier)
+    if ticket_id:
+        query = query.where(AISession.ticket_id == ticket_id)
+    if date_from:
+        query = query.where(AISession.created_at >= date_from)
+    if date_to:
+        query = query.where(AISession.created_at <= date_to)
+    # TODO: Full-text search via q param — see Task 7
 
     result = await db.execute(query)
     sessions = result.scalars().all()