Add endpoint deletion

The endpoints screen could only create and edit servers, so a mistyped
or retired endpoint stayed in the list forever.

Tasks reference endpoints without ON DELETE CASCADE, so a referenced
endpoint is refused with 409 and a count of the tasks using it rather
than cascading away migration history. The foreign-key violation is
mapped to the same status to cover a task created between check and
delete.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

internal/httpapi/endpoints.go

@@ -2,8 +2,11 @@ package httpapi
 
 import (
 	"encoding/json"
+	"errors"
+	"fmt"
 	"net/http"
 
+	"github.com/jackc/pgx/v5/pgconn"
 	"github.com/vasyansk/imap-copier/internal/store"
 )
 
@@ -54,6 +57,36 @@ func (s *Server) handleUpdateEndpoint(w http.ResponseWriter, r *http.Request) {
 	w.WriteHeader(http.StatusNoContent)
 }
 
+// handleDeleteEndpoint removes an endpoint that no task references. A referenced
+// endpoint is refused with 409 rather than a foreign-key error, and the same
+// status covers the race where a task is created between check and delete.
+func (s *Server) handleDeleteEndpoint(w http.ResponseWriter, r *http.Request) {
+	id, err := pathID(r, "id")
+	if err != nil {
+		http.Error(w, "bad id", http.StatusBadRequest)
+		return
+	}
+	used, err := s.store.CountTasksUsingEndpoint(r.Context(), id)
+	if err != nil {
+		http.Error(w, err.Error(), http.StatusInternalServerError)
+		return
+	}
+	if used > 0 {
+		http.Error(w, fmt.Sprintf("endpoint is used by %d task(s) — delete them first", used), http.StatusConflict)
+		return
+	}
+	if err := s.store.DeleteEndpoint(r.Context(), id); err != nil {
+		var pgErr *pgconn.PgError
+		if errors.As(err, &pgErr) && pgErr.Code == "23503" {
+			http.Error(w, "endpoint is used by a task — delete it first", http.StatusConflict)
+			return
+		}
+		http.Error(w, err.Error(), http.StatusInternalServerError)
+		return
+	}
+	w.WriteHeader(http.StatusNoContent)
+}
+
 func (s *Server) handleListEndpoints(w http.ResponseWriter, r *http.Request) {
 	eps, err := s.store.ListEndpoints(r.Context())
 	if err != nil {

internal/httpapi/router.go

@@ -15,6 +15,7 @@ func (s *Server) Router() http.Handler {
 	api.HandleFunc("GET /api/endpoints", s.handleListEndpoints)
 	api.HandleFunc("POST /api/endpoints", s.handleCreateEndpoint)
 	api.HandleFunc("PUT /api/endpoints/{id}", s.handleUpdateEndpoint)
+	api.HandleFunc("DELETE /api/endpoints/{id}", s.handleDeleteEndpoint)
 	api.HandleFunc("GET /api/tasks", s.handleListTasks)
 	api.HandleFunc("POST /api/tasks", s.handleCreateTask)
 	api.HandleFunc("GET /api/tasks/{id}", s.handleGetTask)

internal/store/crud_test.go

@@ -18,6 +18,41 @@ func TestUpdateEndpoint(t *testing.T) {
 	}
 }
 
+func TestDeleteEndpoint(t *testing.T) {
+	s := testStore(t)
+	ctx := context.Background()
+	id, _ := s.CreateEndpoint(ctx, Endpoint{RoleLabel: "src", Host: "a.com", Port: 993, TLSMode: "ssl"})
+	if err := s.DeleteEndpoint(ctx, id); err != nil {
+		t.Fatalf("delete: %v", err)
+	}
+	eps, _ := s.ListEndpoints(ctx)
+	if len(eps) != 0 {
+		t.Fatalf("endpoint not deleted: %d remain", len(eps))
+	}
+}
+
+func TestDeleteEndpointUsedByTaskRefused(t *testing.T) {
+	s := testStore(t)
+	ctx := context.Background()
+	ep1, _ := s.CreateEndpoint(ctx, Endpoint{RoleLabel: "s", Host: "a", Port: 993, TLSMode: "ssl"})
+	ep2, _ := s.CreateEndpoint(ctx, Endpoint{RoleLabel: "d", Host: "b", Port: 993, TLSMode: "ssl"})
+	if _, err := s.CreateTask(ctx, Task{Name: "t", SrcEndpointID: ep1, DstEndpointID: ep2}); err != nil {
+		t.Fatalf("create task: %v", err)
+	}
+	for _, id := range []int64{ep1, ep2} {
+		n, err := s.CountTasksUsingEndpoint(ctx, id)
+		if err != nil {
+			t.Fatalf("count: %v", err)
+		}
+		if n != 1 {
+			t.Fatalf("count for ep %d = %d, want 1", id, n)
+		}
+		if err := s.DeleteEndpoint(ctx, id); err == nil {
+			t.Fatalf("delete of referenced endpoint %d succeeded, want FK violation", id)
+		}
+	}
+}
+
 func TestDeleteAccountCascadesJournal(t *testing.T) {
 	s := testStore(t)
 	ctx := context.Background()

internal/store/endpoints.go

@@ -26,6 +26,23 @@ func (s *Store) UpdateEndpoint(ctx context.Context, e Endpoint) error {
 	return err
 }
 
+// CountTasksUsingEndpoint reports how many tasks reference the endpoint on
+// either side, so a delete can be refused with a meaningful message instead of
+// surfacing a raw foreign-key violation.
+func (s *Store) CountTasksUsingEndpoint(ctx context.Context, id int64) (int, error) {
+	var n int
+	err := s.Pool.QueryRow(ctx,
+		`SELECT count(*) FROM tasks WHERE src_endpoint_id=$1 OR dst_endpoint_id=$1`, id).Scan(&n)
+	return n, err
+}
+
+// DeleteEndpoint removes an endpoint. Tasks reference endpoints without ON
+// DELETE CASCADE, so Postgres rejects the delete while any task still uses it.
+func (s *Store) DeleteEndpoint(ctx context.Context, id int64) error {
+	_, err := s.Pool.Exec(ctx, `DELETE FROM endpoints WHERE id=$1`, id)
+	return err
+}
+
 func (s *Store) GetEndpoint(ctx context.Context, id int64) (Endpoint, error) {
 	var e Endpoint
 	err := s.Pool.QueryRow(ctx,