feat: add ticket solution closure loop

backend/apps/solutions/api.py

@@ -7,6 +7,7 @@ from apps.solutions.schemas import (
     SolutionOut,
     TicketSolutionLinkIn,
     TicketSolutionLinkOut,
+    TicketSolutionOut,
 )
 from apps.tickets.models import Ticket
 
@@ -38,6 +39,25 @@ def list_solutions(request, status: str | None = None):
     return queryset[:100]
 
 
+@router.get("/tickets/{ticket_id}", response=list[TicketSolutionOut])
+def list_ticket_solutions(request, ticket_id: int):
+    require_permission(request, "solution.view")
+    queryset = TicketSolutionLink.objects.select_related("solution", "ticket").filter(
+        ticket_id=ticket_id
+    )
+    return [
+        {
+            "id": link.id,
+            "ticket_id": link.ticket_id,
+            "solution_id": link.solution_id,
+            "link_type": link.link_type,
+            "solution": link.solution,
+            "created_at": link.created_at,
+        }
+        for link in queryset
+    ]
+
+
 @router.get("/{solution_id}", response=SolutionOut)
 def get_solution(request, solution_id: int):
     require_permission(request, "solution.view")

backend/apps/solutions/schemas.py

@@ -42,3 +42,12 @@ class TicketSolutionLinkOut(Schema):
     link_type: str
     solution_usage_count: int
     created_at: datetime
+
+
+class TicketSolutionOut(Schema):
+    id: int
+    ticket_id: int
+    solution_id: int
+    link_type: str
+    solution: SolutionOut
+    created_at: datetime

backend/apps/solutions/tests/test_solution_api.py

@@ -39,3 +39,30 @@ def test_link_solution_to_ticket_increments_usage(admin_client, db):
     assert response.status_code == 200
     assert response.json()["link_type"] == "adopted"
     assert response.json()["solution_usage_count"] == 1
+
+
+def test_list_ticket_solutions_returns_linked_solution_details(admin_client, db):
+    ticket = Ticket.objects.create(ticket_no="TK202607020001", title="A", description="A")
+    solution = admin_client.post(
+        "/api/solutions",
+        data={
+            "title": "Restart callback worker",
+            "problem_signature": "Callback timeout",
+            "root_cause": "Worker queue blocked",
+            "solution": "Restart worker and verify queue depth.",
+            "status": "published",
+        },
+        content_type="application/json",
+    ).json()
+    admin_client.post(
+        f"/api/solutions/{solution['id']}/link-ticket",
+        data={"ticket_id": ticket.id, "link_type": "adopted"},
+        content_type="application/json",
+    )
+
+    response = admin_client.get(f"/api/solutions/tickets/{ticket.id}")
+
+    assert response.status_code == 200
+    payload = response.json()
+    assert payload[0]["link_type"] == "adopted"
+    assert payload[0]["solution"]["title"] == "Restart callback worker"

backend/apps/tickets/services.py

@@ -11,7 +11,7 @@ class TicketStatusError(ValueError):
 ALLOWED_TRANSITIONS: dict[str, set[str]] = {
     "pending_info": {"pending", "closed"},
     "pending": {"in_progress", "closed"},
-    "in_progress": {"pending_confirm", "resolved", "closed"},
+    "in_progress": {"pending_confirm"},
     "pending_confirm": {"resolved", "in_progress", "closed"},
     "resolved": {"closed"},
     "closed": set(),

backend/apps/tickets/tests/test_ticket_status.py

@@ -7,6 +7,16 @@ def test_pending_ticket_can_move_to_in_progress():
     validate_status_transition("pending", "in_progress")
 
 
+def test_in_progress_ticket_must_not_close_directly():
+    with pytest.raises(TicketStatusError, match="in_progress -> closed"):
+        validate_status_transition("in_progress", "closed")
+
+
+def test_in_progress_ticket_must_not_resolve_directly():
+    with pytest.raises(TicketStatusError, match="in_progress -> resolved"):
+        validate_status_transition("in_progress", "resolved")
+
+
 def test_resolved_ticket_cannot_move_back_to_in_progress():
     with pytest.raises(TicketStatusError, match="resolved -> in_progress"):
         validate_status_transition("resolved", "in_progress")