Harden host deletion and test stability

internal/app/http_api.go

@@ -49,6 +49,8 @@ type ActionSet struct {
 	AccessPreview             func(context.Context, AccessPreviewRequest) (AccessPreviewResult, error)
 }
 
+const maxJSONBodyBytes int64 = 1 << 20
+
 type HostInfo struct {
 	HostID       string                    `json:"host_id"`
 	BaseURL      string                    `json:"base_url"`
@@ -834,9 +836,17 @@ func handleDeleteHost(w http.ResponseWriter, r *http.Request, fn func(context.Co
 }
 
 func decodeJSON(r *http.Request, dest any) *httpError {
+	if r == nil {
+		return &httpError{StatusCode: http.StatusBadRequest, Code: "bad_request", Message: "request is required"}
+	}
+	r.Body = http.MaxBytesReader(nil, r.Body, maxJSONBodyBytes)
 	decoder := json.NewDecoder(r.Body)
 	decoder.DisallowUnknownFields()
 	if err := decoder.Decode(dest); err != nil {
+		var maxBytesErr *http.MaxBytesError
+		if errors.As(err, &maxBytesErr) {
+			return &httpError{StatusCode: http.StatusRequestEntityTooLarge, Code: "request_too_large", Message: fmt.Sprintf("request body exceeds %d bytes", maxJSONBodyBytes)}
+		}
 		return &httpError{StatusCode: http.StatusBadRequest, Code: "bad_request", Message: fmt.Sprintf("decode request body: %v", err)}
 	}
 	if err := decoder.Decode(&struct{}{}); err != nil && !errors.Is(err, io.EOF) {
@@ -870,6 +880,10 @@ func classifyError(err error) *httpError {
 	if errors.As(err, &upstreamErr) {
 		return &httpError{StatusCode: http.StatusBadGateway, Code: "host_request_failed", Message: err.Error(), UpstreamStatus: upstreamErr.StatusCode}
 	}
+	var hostDeleteBlocker *sqlite.HostDeleteBlocker
+	if errors.As(err, &hostDeleteBlocker) {
+		return &httpError{StatusCode: http.StatusConflict, Code: "host_in_use", Message: err.Error()}
+	}
 	message := err.Error()
 	switch {
 	case strings.Contains(message, "already installed") || strings.Contains(message, "checksum drift"):
@@ -1254,7 +1268,10 @@ func NewActionSet(sqliteDSN string) ActionSet {
 				return err
 			}
 			defer store.Close()
-			return store.Hosts().DeleteByHostID(ctx, hostID)
+			if err := store.Hosts().DeleteByHostID(ctx, hostID); err != nil {
+				return classifyError(err)
+			}
+			return nil
 		},
 		ListPacks: func(ctx context.Context) ([]PackInfo, error) {
 			store, err := sqlite.Open(ctx, sqliteDSN)